Repair stale documentation anchors for release

.gitignore

@@ -22,6 +22,9 @@
 go.work
 go.work.sum
 
+# Local ReleaseKit executable
+.releasekit/
+
 # env file
 .env
 
@@ -67,4 +70,3 @@ Icon
 .AppleDesktop
 Network Trash Folder
 Temporary Items
-.apdisk

README.md

@@ -21,15 +21,21 @@ Run the maintained offline preparation example from the repository root:
 go run ./examples/go-library/prepare
 ```
 
-It loads a repository-local prompt, supplies a programmatic profile and inline
-input, inspects the captured configuration, and prints deterministic
-preparation metadata without contacting a provider or requiring credentials.
+It composes two explicitly selected synthetic collections, imports
+source-relative prompt content, supplies an inline input, and prepares through
+a scoped view. The example also demonstrates collection inventories and
+namespace-filtered discovery, without contacting a provider or requiring
+credentials.
 The [consumer guide](docs/consumers/pkg-promptkit.md) also shows a local backend,
 ordered file/embedded sources, programmatic mappings, and how to replace an
-engine when source files change. Read the
-[example source](examples/go-library/prepare/main.go), the
+engine when source files change. Applications adapting the prior keyed
+configuration or versioned-prompt format can consult the
+[configuration migration guide](docs/consumers/configuration-migration.md).
+See the [example source](examples/go-library/prepare/main.go), the
 [Go package consumer guide](docs/consumers/pkg-promptkit.md), and the
 [framework format reference](docs/formats.md) to build a consumer workflow.
+The consumer guide also covers explicit, live smoke diagnostics and interpreting
+their factual reports; they are separate from the offline quickstart.
 
 Contributors should start with the [development guide](docs/development.md).
 The [architecture policy](docs/policy/architecture.md) defines the library
@@ -37,6 +43,14 @@ boundary and constraints that framework work must preserve.
 
 ## Release Guidance
 
+The [v0.16.0 release notes](docs/releases/v0.16.0.md) cover explicit smoke
+diagnostics, configuration collections, scoped engine views, and discovery.
+Upgrading consumers should review the breaking changes to bundled configuration
+and prompt version selection and follow the linked migration guide.
+
+The [v0.15.0 release notes](docs/releases/v0.15.0.md) cover error-only
+validation of concrete requests with `Engine.ValidateRequest`.
+
 Consumers upgrading to `v0.12.0` should read the
 [v0.12.0 release notes](docs/releases/v0.12.0.md) for the intentional ConfigKit
 configuration and public construction API migration.

assembled_workflow_benchmark_test.go

@@ -0,0 +1,238 @@
+package promptkit_test
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"strings"
+	"testing"
+	"testing/fstest"
+
+	"gitea.maximumdirect.net/eric/ConfigKit"
+	"gitea.maximumdirect.net/eric/promptkit"
+)
+
+var (
+	assembledPreparedSink *promptkit.PreparedRun
+	assembledResultSink   *promptkit.RunResult
+	assembledDetailsSink  promptkit.PreparedRun
+	assembledHandleSink   *promptkit.PreparedExecution
+)
+
+type assembledWorkflowClient struct{ content string }
+
+func (client assembledWorkflowClient) Generate(
+	context.Context,
+	promptkit.GenerateRequest,
+) (*promptkit.GenerateResponse, error) {
+	return &promptkit.GenerateResponse{Content: client.content}, nil
+}
+
+type assembledWorkflowFixture struct {
+	engine          *promptkit.Engine
+	request         promptkit.RunRequest
+	expectedMessage string
+	response        string
+}
+
+func assembledWorkflowSchema(b *testing.B) []byte {
+	b.Helper()
+	properties := make(map[string]any, 256)
+	for index := range 256 {
+		properties[fmt.Sprintf("property-%03d", index)] = map[string]any{"type": "string"}
+	}
+	data, err := json.Marshal(map[string]any{
+		"$schema":              "https://json-schema.org/draft/2020-12/schema",
+		"type":                 "object",
+		"properties":           properties,
+		"additionalProperties": false,
+	})
+	if err != nil {
+		b.Fatal(err)
+	}
+	return data
+}
+
+func assembledWorkflowExtras(entries int) map[string]any {
+	providers := make(map[string]any, entries)
+	for index := range entries {
+		providers[fmt.Sprintf("provider-%03d", index)] = map[string]any{
+			"enabled": true,
+			"labels":  []any{fmt.Sprintf("tier-%d", index%4), fmt.Sprintf("region-%d", index%3)},
+			"limits":  map[string]any{"burst": index + 1, "period": "minute"},
+			"routes":  []any{map[string]any{"weight": index + 1, "fallback": true}},
+		}
+	}
+	return map[string]any{"provider_options": providers}
+}
+
+func newAssembledWorkflowFixture(b *testing.B, name string) assembledWorkflowFixture {
+	b.Helper()
+	message := "Hello {{.name}}"
+	response := "ok"
+	output := map[string]any{"format": "text", "validation_mode": "none"}
+	profile := map[string]any{"endpoint": "http://example.test/v1", "model": "benchmark-model"}
+	options := []promptkit.Option{promptkit.WithLLMClient(assembledWorkflowClient{content: response})}
+	var expectedMessage string
+
+	switch name {
+	case "small":
+		expectedMessage = "Hello Ada"
+	case "large_message":
+		prefix := strings.Repeat("x", 256*1024)
+		message = prefix + "{{.name}}"
+		expectedMessage = prefix + "Ada"
+	case "mutable_payload":
+		message = `{"subject":"{{.name}}"}`
+		expectedMessage = `{"subject":"Ada"}`
+		response = "{}"
+		profile["extra_params"] = assembledWorkflowExtras(64)
+		output = map[string]any{
+			"format": "json", "validation_mode": "json_schema", "schema_path": "workflow-schema.json",
+		}
+		options[0] = promptkit.WithLLMClient(assembledWorkflowClient{content: response})
+		options = append(options, promptkit.WithSchemaFS(fstest.MapFS{
+			"workflow-schema.json": &fstest.MapFile{Data: assembledWorkflowSchema(b)},
+		}, "."))
+	default:
+		b.Fatalf("unknown assembled workflow fixture %q", name)
+	}
+
+	config := map[string]any{
+		"profiles": map[string]any{"profile": profile},
+		"prompts": map[string]any{"workflow": map[string]any{
+			"version":         "v1",
+			"default_profile": "profile",
+			"messages":        []any{map[string]any{"role": "user", "content": message}},
+			"output":          output,
+		}},
+	}
+	engine, err := promptkit.NewEngine(promptkit.Config{Sources: promptkit.ConfigurationSources{Main: &configkit.Input{
+		Source: configkit.Mapping("assembled workflow benchmark", config),
+	}}}, options...)
+	if err != nil {
+		b.Fatal(err)
+	}
+	request := promptkit.RunRequest{
+		PromptID: "workflow", Vars: map[string]string{"name": "Ada"},
+	}
+	return assembledWorkflowFixture{
+		engine: engine, request: request, expectedMessage: expectedMessage, response: response,
+	}
+}
+
+func verifyAssembledWorkflowFixture(b *testing.B, fixture assembledWorkflowFixture) {
+	b.Helper()
+	ctx := context.Background()
+	prepared, err := fixture.engine.Prepare(ctx, fixture.request)
+	if err != nil {
+		b.Fatal(err)
+	}
+	if prepared.PromptID != "workflow" || prepared.PromptVersion == nil || *prepared.PromptVersion != "v1" || len(prepared.Messages) != 1 ||
+		prepared.Messages[0].Content != fixture.expectedMessage {
+		b.Fatalf("prepared fixture output is invalid: %+v", prepared)
+	}
+	handle, err := fixture.engine.PrepareExecution(ctx, fixture.request)
+	if err != nil {
+		b.Fatal(err)
+	}
+	details := handle.Details()
+	if details.PromptID != "workflow" || len(details.Messages) != 1 || details.Messages[0].Content != fixture.expectedMessage {
+		handle.Discard()
+		b.Fatalf("prepared execution details are invalid: %+v", details)
+	}
+	handle.Discard()
+	result, err := fixture.engine.Run(ctx, fixture.request)
+	if err != nil {
+		b.Fatal(err)
+	}
+	if result.RawOutput != fixture.response {
+		b.Fatalf("run output=%q, want %q", result.RawOutput, fixture.response)
+	}
+	if fixture.response == "{}" && result.Validation.Status != promptkit.ValidationPassed {
+		b.Fatalf("structured response validation=%+v, want passed", result.Validation)
+	}
+}
+
+func BenchmarkEnginePreparation(b *testing.B) {
+	for _, name := range []string{"small", "large_message", "mutable_payload"} {
+		b.Run(name, func(b *testing.B) {
+			fixture := newAssembledWorkflowFixture(b, name)
+			verifyAssembledWorkflowFixture(b, fixture)
+			ctx := context.Background()
+			b.Run("prepare", func(b *testing.B) {
+				b.ReportAllocs()
+				b.ResetTimer()
+				for b.Loop() {
+					prepared, err := fixture.engine.Prepare(ctx, fixture.request)
+					if err != nil {
+						b.Fatal(err)
+					}
+					assembledPreparedSink = prepared
+				}
+				b.StopTimer()
+				assembledPreparedSink = nil
+			})
+			b.Run("prepared_execution_creation_and_discard", func(b *testing.B) {
+				b.ReportAllocs()
+				b.ResetTimer()
+				for b.Loop() {
+					handle, err := fixture.engine.PrepareExecution(ctx, fixture.request)
+					if err != nil {
+						b.Fatal(err)
+					}
+					handle.Discard()
+					assembledHandleSink = handle
+				}
+				b.StopTimer()
+				assembledHandleSink = nil
+			})
+		})
+	}
+}
+
+func BenchmarkEngineRun(b *testing.B) {
+	for _, name := range []string{"small", "large_message", "mutable_payload"} {
+		b.Run(name, func(b *testing.B) {
+			fixture := newAssembledWorkflowFixture(b, name)
+			verifyAssembledWorkflowFixture(b, fixture)
+			ctx := context.Background()
+			b.ReportAllocs()
+			b.ResetTimer()
+			for b.Loop() {
+				result, err := fixture.engine.Run(ctx, fixture.request)
+				if err != nil {
+					b.Fatal(err)
+				}
+				assembledResultSink = result
+			}
+			b.StopTimer()
+			assembledResultSink = nil
+		})
+	}
+}
+
+func BenchmarkPreparedExecutionDetails(b *testing.B) {
+	for _, name := range []string{"small", "large_message", "mutable_payload"} {
+		b.Run(name, func(b *testing.B) {
+			fixture := newAssembledWorkflowFixture(b, name)
+			verifyAssembledWorkflowFixture(b, fixture)
+			handle, err := fixture.engine.PrepareExecution(context.Background(), fixture.request)
+			if err != nil {
+				b.Fatal(err)
+			}
+			defer handle.Discard()
+			initial := handle.Details()
+			if len(initial.Messages) != 1 || initial.Messages[0].Content != fixture.expectedMessage {
+				b.Fatalf("prepared details fixture is invalid: %+v", initial)
+			}
+			b.ReportAllocs()
+			b.ResetTimer()
+			for b.Loop() {
+				assembledDetailsSink = handle.Details()
+			}
+			b.StopTimer()
+			assembledDetailsSink = promptkit.PreparedRun{}
+		})
+	}
+}

backends.go

@@ -5,10 +5,10 @@ import (
 	"gitea.maximumdirect.net/eric/promptkit/internal/backend"
 )
 
-// BackendOpenRouter identifies the maintained OpenRouter backend.
+// BackendOpenRouter is the conventional ID for an OpenRouter backend.
 const BackendOpenRouter = backend.OpenRouterID
 
-// BackendRakestrawHome identifies the maintained Rakestrawhome backend.
+// BackendRakestrawHome is the conventional ID for a Rakestrawhome backend.
 const BackendRakestrawHome = backend.RakestrawHomeID
 
 // BackendLocal is a conventional ID for a caller-configured local backend.
@@ -17,8 +17,9 @@ const BackendLocal = "local"
 // BackendConfig is a presence-aware convenience value for a keyed backend
 // definition. Nil pointer fields are omitted, while non-nil pointers preserve
 // explicit zero or blank values. A nil ExtraParams map is omitted; a non-nil
-// empty map supplies an empty mapping. Use raw ConfigKit Mapping inputs for
-// explicit null. BackendConfig has no stable JSON representation.
+// empty map supplies an empty mapping. A nil SmokeTests pointer is omitted; a
+// non-nil pointer supplies a smoke_tests mapping. Use raw ConfigKit Mapping
+// inputs for explicit null. BackendConfig has no stable JSON representation.
 type BackendConfig struct {
 	// Endpoint is the required absolute HTTP(S) base URL after all layers merge.
 	Endpoint *string
@@ -31,6 +32,43 @@ type BackendConfig struct {
 	QueueCapacity *int
 	// ExtraParams supplies JSON-compatible provider request defaults.
 	ExtraParams map[string]any
+	// SmokeTests supplies optional diagnostic defaults and HTTP probe settings.
+	SmokeTests *BackendSmokeTestConfig
+}
+
+// BackendSmokeTestConfig contains optional diagnostic settings associated with
+// a backend. Nil nested fields are omitted by BackendSource.
+type BackendSmokeTestConfig struct {
+	// DefaultProfile is the exact profile ID selected as the backend's
+	// diagnostic inference default. A supplied value must not be blank; the ID
+	// is resolved only when that default is selected.
+	DefaultProfile *string
+	// Reachability optionally selects a full HTTP destination for reachability
+	// diagnostics. A nil endpoint uses the effective backend endpoint.
+	Reachability *ReachabilityProbeConfig
+	// Authentication optionally declares a named authentication diagnostic.
+	// A supplied object requires Kind.
+	Authentication *AuthenticationProbeConfig
+}
+
+// ReachabilityProbeConfig configures an optional reachability destination.
+type ReachabilityProbeConfig struct {
+	// Endpoint is an absolute HTTP(S) URL, including any desired path or query.
+	// Nil selects the effective backend endpoint; an explicit blank value is
+	// invalid.
+	Endpoint *string
+}
+
+// AuthenticationProbeConfig configures an optional named authentication
+// diagnostic.
+type AuthenticationProbeConfig struct {
+	// Kind selects the authentication adapter. Supported values are "none" and
+	// "openrouter_key"; surrounding whitespace and case are normalized.
+	Kind *string
+	// Endpoint is an absolute HTTP(S) URL, including any desired path or query.
+	// Nil selects the adapter's backend-relative destination; an explicit blank
+	// value is invalid.
+	Endpoint *string
 }
 
 // BackendSource creates a labeled ConfigKit mapping from keyed backend values.
@@ -57,6 +95,30 @@ func BackendSource(label string, backends map[string]BackendConfig) configkit.So
 		if config.ExtraParams != nil {
 			fields["extra_params"] = providerMapForMapping(config.ExtraParams)
 		}
+		if config.SmokeTests != nil {
+			smokeTests := make(map[string]any)
+			if config.SmokeTests.DefaultProfile != nil {
+				smokeTests["default_profile"] = *config.SmokeTests.DefaultProfile
+			}
+			if config.SmokeTests.Reachability != nil {
+				reachability := make(map[string]any)
+				if config.SmokeTests.Reachability.Endpoint != nil {
+					reachability["endpoint"] = *config.SmokeTests.Reachability.Endpoint
+				}
+				smokeTests["reachability"] = reachability
+			}
+			if config.SmokeTests.Authentication != nil {
+				authentication := make(map[string]any)
+				if config.SmokeTests.Authentication.Kind != nil {
+					authentication["kind"] = *config.SmokeTests.Authentication.Kind
+				}
+				if config.SmokeTests.Authentication.Endpoint != nil {
+					authentication["endpoint"] = *config.SmokeTests.Authentication.Endpoint
+				}
+				smokeTests["authentication"] = authentication
+			}
+			fields["smoke_tests"] = smokeTests
+		}
 		definitions[id] = fields
 	}
 	return configkit.Mapping(label, map[string]any{"backends": definitions})

capacity_contract_test.go

@@ -267,7 +267,7 @@ func newBackendCapacityEngine(
 		Source: configkit.Mapping("capacity fixture", map[string]any{
 			"backends": map[string]any{"limited": backend},
 			"profiles": map[string]any{"profile": map[string]any{"backend": "limited", "model": "model"}},
-			"prompts":  map[string]any{promptID: map[string]any{"1": definition}},
+			"prompts":  map[string]any{promptID: promptDefinitionWithVersion("1", definition)},
 		}),
 	}}}, options...)
 	if err != nil {

configuration_diff_contract_test.go

@@ -0,0 +1,243 @@
+package promptkit_test
+
+import (
+	"errors"
+	"strings"
+	"testing"
+
+	"gitea.maximumdirect.net/eric/ConfigKit"
+	"gitea.maximumdirect.net/eric/promptkit"
+)
+
+func TestConfigurationInspectionDiffsCapturedValues(t *testing.T) {
+	left := comparisonInspection(t, "earlier-model")
+	right := comparisonInspection(t, "later-model")
+
+	differences, err := left.Diff(right)
+	if err != nil {
+		t.Fatalf("compare captured configurations: %v", err)
+	}
+	if len(differences) != 1 {
+		t.Fatalf("difference count = %d, want 1: %+v", len(differences), differences)
+	}
+	difference := differences[0]
+	if got, want := difference.Path.String(), "/profiles/offline/model"; got != want {
+		t.Fatalf("difference path = %q, want %q", got, want)
+	}
+	if !strings.Contains(difference.Left.YAML, "earlier-model") || !strings.Contains(difference.Right.YAML, "later-model") {
+		t.Fatalf("difference snapshots = (%q, %q)", difference.Left.YAML, difference.Right.YAML)
+	}
+
+	reversed, err := right.Diff(left)
+	if err != nil {
+		t.Fatalf("compare reversed configurations: %v", err)
+	}
+	if len(reversed) != 1 || reversed[0].Path.String() != difference.Path.String() ||
+		!strings.Contains(reversed[0].Left.YAML, "later-model") ||
+		!strings.Contains(reversed[0].Right.YAML, "earlier-model") {
+		t.Fatalf("reversed difference = %+v", reversed)
+	}
+
+	equal := comparisonInspection(t, "earlier-model")
+	if equal, err := left.Diff(equal); err != nil || len(equal) != 0 {
+		t.Fatalf("compare equal configurations = (%+v, %v), want no differences", equal, err)
+	}
+	if equal, err := left.Diff(left); err != nil || len(equal) != 0 {
+		t.Fatalf("compare view with itself = (%+v, %v), want no differences", equal, err)
+	}
+}
+
+func TestConfigurationInspectionDiffRejectsZeroViews(t *testing.T) {
+	valid := comparisonInspection(t, "current-model")
+	var zero promptkit.ConfigurationInspection
+
+	for _, comparison := range []struct {
+		name        string
+		left, right promptkit.ConfigurationInspection
+	}{
+		{name: "zero left", left: zero, right: valid},
+		{name: "zero right", left: valid, right: zero},
+		{name: "both zero", left: zero, right: zero},
+	} {
+		t.Run(comparison.name, func(t *testing.T) {
+			differences, err := comparison.left.Diff(comparison.right)
+			if !errors.Is(err, promptkit.ErrInvalidConfig) || len(differences) != 0 {
+				t.Fatalf("Diff() = (%+v, %v), want ErrInvalidConfig and no records", differences, err)
+			}
+		})
+	}
+}
+
+func TestConfigurationInspectionDiffIgnoresSourceHistory(t *testing.T) {
+	left := comparisonInspectionFrom(t, "earlier source", "same-model", nil)
+	right := comparisonInspectionFrom(t, "later source", "same-model", nil)
+	if !hasSourceLabel(left, "earlier source") || !hasSourceLabel(right, "later source") {
+		t.Fatal("comparison fixtures did not retain their distinct source labels")
+	}
+
+	differences, err := left.Diff(right)
+	if err != nil || len(differences) != 0 {
+		t.Fatalf("compare equal effective values with different sources = (%+v, %v), want no differences", differences, err)
+	}
+}
+
+func TestConfigurationInspectionDiffReportsPresenceAndSequences(t *testing.T) {
+	left := comparisonInspectionFrom(t, "before", "same-model", map[string]any{
+		"sequence": []any{"earlier", "unchanged"},
+	})
+	right := comparisonInspectionFrom(t, "after", "same-model", map[string]any{
+		"nullable": nil,
+		"sequence": []any{"later", "unchanged"},
+	})
+
+	differences, err := left.Diff(right)
+	if err != nil {
+		t.Fatalf("compare presence and sequence values: %v", err)
+	}
+	if len(differences) != 2 {
+		t.Fatalf("difference count = %d, want 2: %+v", len(differences), differences)
+	}
+	byPath := differencesByPath(differences)
+	nullable, ok := byPath["/backends/local/extra_params/nullable"]
+	if !ok || nullable.Left.Present || !nullable.Right.Present || strings.TrimSpace(nullable.Right.YAML) != "null" {
+		t.Fatalf("absent-to-null difference = (%+v, %t)", nullable, ok)
+	}
+	sequence, ok := byPath["/backends/local/extra_params/sequence"]
+	if !ok || !sequence.Left.Present || !sequence.Right.Present ||
+		!strings.Contains(sequence.Left.YAML, "earlier") || !strings.Contains(sequence.Right.YAML, "later") {
+		t.Fatalf("atomic sequence difference = (%+v, %t)", sequence, ok)
+	}
+}
+
+func TestConfigurationInspectionDiffProtectsSensitiveValuesAndReturnedRecords(t *testing.T) {
+	left := comparisonInspectionFrom(t, "before", "same-model", map[string]any{
+		"token":   "left-secret-sentinel",
+		"visible": "before-value",
+	})
+	right := comparisonInspectionFrom(t, "after", "same-model", map[string]any{
+		"token":   "right-secret-sentinel",
+		"visible": "after-value",
+	})
+
+	differences, err := left.Diff(right)
+	if err != nil {
+		t.Fatalf("compare sensitive values: %v", err)
+	}
+	if len(differences) != 2 {
+		t.Fatalf("difference count = %d, want 2: %+v", len(differences), differences)
+	}
+	byPath := differencesByPath(differences)
+	secret, ok := byPath["/backends/local/extra_params/token"]
+	if !ok || !secret.Left.Redacted || !secret.Right.Redacted || !secret.HiddenChanged {
+		t.Fatalf("sensitive difference = (%+v, %t)", secret, ok)
+	}
+	if strings.Contains(secret.Left.YAML, "left-secret-sentinel") || strings.Contains(secret.Left.YAML, "right-secret-sentinel") ||
+		strings.Contains(secret.Right.YAML, "left-secret-sentinel") || strings.Contains(secret.Right.YAML, "right-secret-sentinel") {
+		t.Fatalf("sensitive snapshots disclosed a value: %+v", secret)
+	}
+	visible, ok := byPath["/backends/local/extra_params/visible"]
+	if !ok || visible.Left.Redacted || visible.Right.Redacted || visible.HiddenChanged ||
+		!strings.Contains(visible.Left.YAML, "before-value") || !strings.Contains(visible.Right.YAML, "after-value") {
+		t.Fatalf("public sibling difference = (%+v, %t)", visible, ok)
+	}
+
+	differences[0].Path = configkit.Keys("caller", "mutation")
+	differences[0].Left.YAML = "caller mutation"
+	differences[0].Right.YAML = "caller mutation"
+	again, err := left.Diff(right)
+	if err != nil {
+		t.Fatalf("repeat comparison after mutating returned records: %v", err)
+	}
+	if len(again) != 2 {
+		t.Fatalf("repeat difference count = %d, want 2: %+v", len(again), again)
+	}
+	againByPath := differencesByPath(again)
+	if _, exists := againByPath["/caller/mutation"]; exists {
+		t.Fatal("mutating returned path reached retained inspection")
+	}
+	if _, exists := againByPath["/backends/local/extra_params/token"]; !exists {
+		t.Fatalf("original sensitive path was lost after mutation: %+v", again)
+	}
+	if _, exists := againByPath["/backends/local/extra_params/visible"]; !exists {
+		t.Fatalf("original public path was lost after mutation: %+v", again)
+	}
+	for _, difference := range again {
+		if difference.Left.YAML == "caller mutation" || difference.Right.YAML == "caller mutation" {
+			t.Fatalf("mutating returned snapshots reached retained inspection: %+v", difference)
+		}
+	}
+}
+
+func TestConfigurationInspectionDiffMasksSensitiveShapeReplacement(t *testing.T) {
+	left := comparisonInspectionFrom(t, "before", "same-model", map[string]any{
+		"details": map[string]any{
+			"token": "nested-secret-sentinel",
+			"label": "public detail",
+		},
+	})
+	right := comparisonInspectionFrom(t, "after", "same-model", map[string]any{
+		"details": "replacement",
+	})
+
+	differences, err := left.Diff(right)
+	if err != nil {
+		t.Fatalf("compare sensitive shape replacement: %v", err)
+	}
+	if len(differences) != 1 || differences[0].Path.String() != "/backends/local/extra_params/details" {
+		t.Fatalf("shape replacement differences = %+v", differences)
+	}
+	difference := differences[0]
+	if !difference.Left.Redacted || !difference.Right.Redacted || !difference.HiddenChanged {
+		t.Fatalf("shape replacement masking = %+v", difference)
+	}
+	if strings.Contains(difference.Left.YAML, "nested-secret-sentinel") || strings.Contains(difference.Right.YAML, "nested-secret-sentinel") {
+		t.Fatalf("shape replacement disclosed a sensitive value: %+v", difference)
+	}
+}
+
+func comparisonInspection(t *testing.T, model string) promptkit.ConfigurationInspection {
+	t.Helper()
+	return comparisonInspectionFrom(t, "comparison fixture", model, nil)
+}
+
+func comparisonInspectionFrom(t *testing.T, source, model string, extraParams map[string]any) promptkit.ConfigurationInspection {
+	t.Helper()
+	backend := map[string]any{"endpoint": "https://example.invalid/v1"}
+	if extraParams != nil {
+		backend["extra_params"] = extraParams
+	}
+	engine, err := promptkit.NewEngine(promptkit.Config{Sources: promptkit.ConfigurationSources{
+		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{{Source: configkit.Mapping(source, map[string]any{
+			"backends": map[string]any{"local": backend},
+			"profiles": map[string]any{"offline": map[string]any{
+				"backend": "local",
+				"model":   model,
+			}},
+		})}}}},
+	}})
+	if err != nil {
+		t.Fatalf("construct comparison engine: %v", err)
+	}
+	inspection, err := engine.InspectConfiguration()
+	if err != nil {
+		t.Fatalf("inspect comparison engine: %v", err)
+	}
+	return inspection
+}
+
+func differencesByPath(differences []configkit.Difference) map[string]configkit.Difference {
+	byPath := make(map[string]configkit.Difference, len(differences))
+	for _, difference := range differences {
+		byPath[difference.Path.String()] = difference
+	}
+	return byPath
+}
+
+func hasSourceLabel(view promptkit.ConfigurationInspection, label string) bool {
+	for _, source := range view.Sources() {
+		if source.Label == label {
+			return true
+		}
+	}
+	return false
+}

configuration_inspection.go

@@ -27,6 +27,23 @@ func (e *Engine) InspectConfiguration() (ConfigurationInspection, error) {
 	return ConfigurationInspection{source: e.internal.InspectConfiguration()}, nil
 }
 
+// Diff compares this view's captured effective configuration with other. This
+// view is the earlier (left) value and other is the later (right) value. The
+// comparison delegates to ConfigKit's frozen effective-value semantics, so
+// source or resolution history alone does not create differences. It does not
+// reread external sources or compare referenced file contents, resolved
+// credential contents, later execution preparation, or request-specific
+// overrides. Either zero view returns ErrInvalidConfig and no records; other
+// ConfigKit errors are returned unchanged. An empty diff is not evidence of
+// equivalent engine behavior or execution. Records can contain ordinary
+// application data, so callers choose where and to whom to disclose them.
+func (v ConfigurationInspection) Diff(other ConfigurationInspection) ([]configkit.Difference, error) {
+	if v.source == nil || other.source == nil {
+		return nil, ErrInvalidConfig
+	}
+	return configuration.Diff(v.source, other.source)
+}
+
 // Metadata returns detached effective presence and history records.
 func (v ConfigurationInspection) Metadata() configkit.Metadata {
 	if v.source == nil {

configuration_inspection_contract_test.go

@@ -23,13 +23,19 @@ func TestConfigurationInspectionReportsLiteralKeysAndRedactedHistory(t *testing.
 					"endpoint": "https://example.invalid/v1", "api_key_env": "OPTIONAL_KEY",
 					"extra_params": map[string]any{"token": "private-sentinel", "visible": "public-value"},
 				}},
-				"profiles": map[string]any{
-					"base.v1":    map[string]any{"backend": "local", "model": "default-model"},
-					"literal/id": map[string]any{"extends": "base.v1"},
-				},
+				"collections": map[string]any{"literal": map[string]any{
+					"backends": map[string]any{"local": map[string]any{
+						"endpoint":     "https://example.invalid/v1",
+						"extra_params": map[string]any{"token": "namespaced-private-sentinel"},
+					}},
+					"profiles": map[string]any{
+						"base.v1": map[string]any{"backend": "local", "model": "default-model"},
+						"id":      map[string]any{"extends": "base.v1"},
+					},
+				}},
 			})}}},
 			{Inputs: []configkit.Input{{Source: configkit.Mapping("operator", map[string]any{
-				"profiles": map[string]any{"base.v1": map[string]any{"model": "operator-model"}},
+				"collections": map[string]any{"literal": map[string]any{"profiles": map[string]any{"base.v1": map[string]any{"model": "operator-model"}}}},
 			})}}},
 		},
 	}})
@@ -40,17 +46,17 @@ func TestConfigurationInspectionReportsLiteralKeysAndRedactedHistory(t *testing.
 	if err != nil {
 		t.Fatalf("inspect configuration: %v", err)
 	}
-	modelPath := configkit.Keys("profiles", "base.v1", "model")
+	modelPath := configkit.Keys("collections", "literal", "profiles", "base.v1", "model")
 	model, found := view.Explain(modelPath)
 	if !found || !strings.Contains(model.Effective.YAML, "operator-model") || len(model.History) < 2 {
 		t.Fatalf("layered model explanation = (%+v, %t)", model, found)
 	}
-	inheritedPath := configkit.Keys("profiles", "literal/id", "model")
+	inheritedPath := configkit.Keys("collections", "literal", "profiles", "id", "model")
 	inherited, found := view.Explain(inheritedPath)
 	if !found || !strings.Contains(inherited.Effective.YAML, "operator-model") || len(inherited.History) == 0 || !view.Metadata().IsExplicit(inheritedPath) {
 		t.Fatalf("literal-key inheritance explanation = (%+v, %t)", inherited, found)
 	}
-	if inheritedPath.String() != "/profiles/literal~1id/model" {
+	if inheritedPath.String() != "/collections/literal/profiles/id/model" {
 		t.Fatalf("literal-key path = %q", inheritedPath)
 	}
 	secretPath := configkit.Keys("backends", "local", "extra_params", "token")
@@ -58,6 +64,11 @@ func TestConfigurationInspectionReportsLiteralKeysAndRedactedHistory(t *testing.
 	if !found || !secret.Effective.Redacted || strings.Contains(secret.Effective.YAML, "private-sentinel") {
 		t.Fatalf("credential-shaped provider value was not redacted: (%+v, %t)", secret, found)
 	}
+	namespacedSecretPath := configkit.Keys("collections", "literal", "backends", "local", "extra_params", "token")
+	namespacedSecret, found := view.Explain(namespacedSecretPath)
+	if !found || !namespacedSecret.Effective.Redacted || strings.Contains(namespacedSecret.Effective.YAML, "namespaced-private-sentinel") {
+		t.Fatalf("namespaced provider value was not redacted: (%+v, %t)", namespacedSecret, found)
+	}
 	var effective bytes.Buffer
 	if err := view.WriteEffective(&effective); err != nil {
 		t.Fatalf("write effective configuration: %v", err)
@@ -66,7 +77,7 @@ func TestConfigurationInspectionReportsLiteralKeysAndRedactedHistory(t *testing.
 		t.Fatalf("unexpected effective report: %s", effective.String())
 	}
 	var explanation bytes.Buffer
-	if err := view.WriteExplanation(&explanation, secretPath); err != nil || strings.Contains(explanation.String(), "private-sentinel") {
+	if err := view.WriteExplanation(&explanation, namespacedSecretPath); err != nil || strings.Contains(explanation.String(), "namespaced-private-sentinel") {
 		t.Fatalf("secret explanation = (%q, %v)", explanation.String(), err)
 	}
 
@@ -93,6 +104,28 @@ func TestConfigurationInspectionReportsLiteralKeysAndRedactedHistory(t *testing.
 	}
 }
 
+func TestConfigurationInspectionRetainsMainSpecificationDeclaration(t *testing.T) {
+	engine, err := promptkit.NewEngine(promptkit.Config{Sources: promptkit.ConfigurationSources{Main: &configkit.Input{
+		Source: configkit.Mapping("main", map[string]any{"version": "1"}),
+	}}})
+	if err != nil {
+		t.Fatalf("construct engine with accepted declaration: %v", err)
+	}
+	inspection, err := engine.InspectConfiguration()
+	if err != nil {
+		t.Fatalf("inspect configuration: %v", err)
+	}
+	path := configkit.Keys("version")
+	field, found := inspection.Explain(path)
+	if !found || !inspection.Metadata().IsExplicit(path) || !strings.Contains(field.Effective.YAML, "1") {
+		t.Fatalf("main specification declaration was not retained: (%+v, %t)", field, found)
+	}
+	var effective bytes.Buffer
+	if err := inspection.WriteEffective(&effective); err != nil || !strings.Contains(effective.String(), "version") {
+		t.Fatalf("effective inspection = (%q, %v), want retained version", effective.String(), err)
+	}
+}
+
 type failingInspectionWriter struct{ err error }
 
 func (writer failingInspectionWriter) Write([]byte) (int, error) { return 0, writer.err }
@@ -117,7 +150,13 @@ func TestConfigurationInspectionZeroAndWriterErrors(t *testing.T) {
 		t.Fatalf("zero explanation writer = %v", err)
 	}
 
-	valid, err := promptkit.NewEngine(promptkit.Config{})
+	endpoint, model := "https://configured.example/v1", "configured-model"
+	profile := configkit.Input{Source: promptkit.ProfileSource("inspection test profile", map[string]promptkit.ProfileConfig{
+		"inspection-profile": {Endpoint: &endpoint, Model: &model},
+	})}
+	valid, err := promptkit.NewEngine(promptkit.Config{Sources: promptkit.ConfigurationSources{
+		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{profile}}},
+	}})
 	if err != nil {
 		t.Fatalf("construct engine: %v", err)
 	}
@@ -130,7 +169,7 @@ func TestConfigurationInspectionZeroAndWriterErrors(t *testing.T) {
 	if err := view.WriteEffective(writer); !errors.Is(err, writeErr) {
 		t.Fatalf("effective writer error = %v", err)
 	}
-	if err := view.WriteExplanation(writer, configkit.Keys("profiles", "mistral-small-3", "model")); !errors.Is(err, writeErr) {
+	if err := view.WriteExplanation(writer, configkit.Keys("profiles", "inspection-profile", "model")); !errors.Is(err, writeErr) {
 		t.Fatalf("explanation writer error = %v", err)
 	}
 }
@@ -144,9 +183,17 @@ func TestConfigurationInspectionUsesCapturedSourcesWithoutProviderCalls(t *testi
 	if err != nil {
 		t.Fatalf("select inputs: %v", err)
 	}
+	otherSource := &unreadableAfterConstructionFS{FS: fstest.MapFS{
+		"config/prompt.yaml": &fstest.MapFile{Data: []byte(capturedPromptDocument)},
+		"config/body.tmpl":   &fstest.MapFile{Data: []byte("hello")},
+	}}
+	otherInputs, err := promptkit.FilesystemInputs("comparison source", otherSource, "config")
+	if err != nil {
+		t.Fatalf("select comparison inputs: %v", err)
+	}
 	var modelCalls atomic.Int64
 	client := countingLLMClient{calls: &modelCalls}
-	endpoint, model := "https://example.invalid/v1", "offline-model"
+	endpoint, model, otherModel := "https://example.invalid/v1", "offline-model", "comparison-model"
 	engine, err := promptkit.NewEngine(promptkit.Config{Sources: promptkit.ConfigurationSources{
 		Underlays: []configkit.Underlay{{Inputs: inputs}, {Inputs: []configkit.Input{{Source: promptkit.ProfileSource("offline profile", map[string]promptkit.ProfileConfig{
 			"offline": {Endpoint: &endpoint, Model: &model},
@@ -155,36 +202,75 @@ func TestConfigurationInspectionUsesCapturedSourcesWithoutProviderCalls(t *testi
 	if err != nil {
 		t.Fatalf("construct engine: %v", err)
 	}
+	otherEngine, err := promptkit.NewEngine(promptkit.Config{Sources: promptkit.ConfigurationSources{
+		Underlays: []configkit.Underlay{{Inputs: otherInputs}, {Inputs: []configkit.Input{{Source: promptkit.ProfileSource("comparison profile", map[string]promptkit.ProfileConfig{
+			"offline": {Endpoint: &endpoint, Model: &otherModel},
+		})}}}},
+	}}, promptkit.WithLLMClient(client))
+	if err != nil {
+		t.Fatalf("construct comparison engine: %v", err)
+	}
 	source.closed.Store(true)
+	otherSource.closed.Store(true)
 	view, err := engine.InspectConfiguration()
 	if err != nil {
 		t.Fatalf("inspect configuration: %v", err)
 	}
-	if _, found := view.Explain(configkit.Keys("prompts", "captured", "1", "messages").Index(0).Key("content_file")); !found {
+	otherView, err := otherEngine.InspectConfiguration()
+	if err != nil {
+		t.Fatalf("inspect comparison configuration: %v", err)
+	}
+	var expected configkit.Difference
+	for index := 0; index < 3; index++ {
+		differences, err := view.Diff(otherView)
+		if err != nil || len(differences) != 1 {
+			t.Fatalf("compare captured configurations = (%+v, %v), want one difference", differences, err)
+		}
+		if differences[0].Path.String() != "/profiles/offline/model" ||
+			!strings.Contains(differences[0].Left.YAML, model) ||
+			!strings.Contains(differences[0].Right.YAML, otherModel) {
+			t.Fatalf("captured difference = %+v", differences[0])
+		}
+		if index == 0 {
+			expected = differences[0]
+		} else if differences[0].Path.String() != expected.Path.String() ||
+			differences[0].Left.YAML != expected.Left.YAML || differences[0].Right.YAML != expected.Right.YAML {
+			t.Fatalf("captured difference changed between reads: first=%+v next=%+v", expected, differences[0])
+		}
+	}
+	if _, found := view.Explain(configkit.Keys("prompts", "captured", "messages").Index(0).Key("content_file")); !found {
 		t.Fatal("captured prompt content path was not inspectable")
 	}
 	var report bytes.Buffer
 	if err := view.WriteEffective(&report); err != nil || !strings.Contains(report.String(), "captured") {
 		t.Fatalf("write captured report = (%q, %v)", report.String(), err)
 	}
-	if source.reads.Load() != 0 || modelCalls.Load() != 0 {
-		t.Fatalf("inspection touched source or provider: reads=%d requests=%d", source.reads.Load(), modelCalls.Load())
+	if source.reads.Load() != 0 || otherSource.reads.Load() != 0 || modelCalls.Load() != 0 {
+		t.Fatalf("inspection or comparison touched source or provider: reads=(%d,%d) requests=%d", source.reads.Load(), otherSource.reads.Load(), modelCalls.Load())
 	}
 
-	const calls = 16
+	const calls = 24
 	var wait sync.WaitGroup
 	errs := make(chan error, calls)
 	for index := 0; index < calls; index++ {
 		wait.Add(1)
 		go func(index int) {
 			defer wait.Done()
-			if index%2 == 0 {
+			switch index % 3 {
+			case 0:
 				_, err := engine.InspectConfiguration()
 				errs <- err
-				return
+			case 1:
+				_, err := engine.Run(context.Background(), promptkit.RunRequest{PromptID: "captured", SessionID: "direct"})
+				errs <- err
+			case 2:
+				differences, err := view.Diff(otherView)
+				if err == nil && (len(differences) != 1 || differences[0].Path.String() != expected.Path.String() ||
+					differences[0].Left.YAML != expected.Left.YAML || differences[0].Right.YAML != expected.Right.YAML) {
+					err = errors.New("concurrent comparison returned an unexpected difference")
+				}
+				errs <- err
 			}
-			_, err := engine.Run(context.Background(), promptkit.RunRequest{PromptID: "captured", SessionID: "direct"})
-			errs <- err
 		}(index)
 	}
 	wait.Wait()
@@ -194,7 +280,7 @@ func TestConfigurationInspectionUsesCapturedSourcesWithoutProviderCalls(t *testi
 			t.Fatal(err)
 		}
 	}
-	if source.reads.Load() != 0 || modelCalls.Load() != calls/2 {
-		t.Fatalf("concurrent inspection/execution = source reads %d, model calls %d", source.reads.Load(), modelCalls.Load())
+	if source.reads.Load() != 0 || otherSource.reads.Load() != 0 || modelCalls.Load() != calls/3 {
+		t.Fatalf("concurrent inspection/comparison/execution = source reads (%d,%d), model calls %d", source.reads.Load(), otherSource.reads.Load(), modelCalls.Load())
 	}
 }

configuration_sources.go

@@ -8,9 +8,26 @@ import (
 	"path/filepath"
 
 	"gitea.maximumdirect.net/eric/ConfigKit"
+	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
 	"gitea.maximumdirect.net/eric/promptkit/internal/filecatalog"
 )
 
+// CollectionInput mounts source at the selected collection's configuration
+// destination, collections/<namespace>, and enables ConfigKit imports for that
+// input. An invalid namespace returns an error matching ErrInvalidConfig. The
+// source is not read or validated until ConfigKit loads it. Callers may adjust
+// the returned input, including its filesystem context or imports setting.
+func CollectionInput(namespace string, source configkit.Source) (configkit.Input, error) {
+	if !domain.IsValidResourceNamespace(namespace) {
+		return configkit.Input{}, fmt.Errorf("%w: invalid collection namespace %q", ErrInvalidConfig, namespace)
+	}
+	return configkit.Input{
+		Source:      source,
+		Destination: configkit.Keys("collections", namespace),
+		Imports:     true,
+	}, nil
+}
+
 // DirectoryInputs selects the YAML files beneath an explicitly chosen host
 // directory as one strict-composition group. The returned order is deterministic;
 // it does not assign precedence among those files. Discovery is recursive over

configuration_sources_test.go

@@ -1,6 +1,8 @@
 package promptkit_test
 
 import (
+	"context"
+	"errors"
 	"io/fs"
 	"os"
 	"path/filepath"
@@ -16,6 +18,78 @@ type sourceDocument struct {
 	Second string `yaml:"second"`
 }
 
+func TestCollectionInputValidatesWithoutReadingSource(t *testing.T) {
+	input, err := promptkit.CollectionInput("docs", configkit.File(filepath.Join(t.TempDir(), "not-read.yaml")))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if input.Destination.String() != "/collections/docs" || !input.Imports {
+		t.Fatalf("collection input = %+v, want destination /collections/docs with imports enabled", input)
+	}
+	for _, namespace := range []string{"", " ", "docs/api"} {
+		if _, err := promptkit.CollectionInput(namespace, configkit.NoSource()); !errors.Is(err, promptkit.ErrInvalidConfig) {
+			t.Errorf("namespace %q error = %v, want ErrInvalidConfig", namespace, err)
+		}
+	}
+}
+
+func TestCollectionInputLoadsNativeImportsAndLaterOverride(t *testing.T) {
+	directory := t.TempDir()
+	mainPath := filepath.Join(directory, "collection.yaml")
+	defaultsPath := filepath.Join(directory, "defaults.yaml")
+	if err := os.WriteFile(mainPath, []byte("configkit:\n  imports:\n    - path: defaults.yaml\n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(defaultsPath, []byte("prompts:\n  greeting:\n    version: imported\n    messages:\n      - role: user\n        content: Hello\n    output:\n      format: text\n      validation_mode: none\n"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	input, err := promptkit.CollectionInput("docs", configkit.File(mainPath))
+	if err != nil {
+		t.Fatal(err)
+	}
+	engine, err := promptkit.NewEngine(promptkit.Config{Sources: promptkit.ConfigurationSources{
+		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{input}}},
+		Main: &configkit.Input{
+			Source:      configkit.Mapping("later collection override", map[string]any{"prompts": map[string]any{"greeting": map[string]any{"version": "overridden"}}}),
+			Destination: configkit.Keys("collections", "docs"),
+		},
+	}})
+	if err != nil {
+		t.Fatalf("construct engine with native collection import: %v", err)
+	}
+	inspection, err := engine.InspectPrompt(context.Background(), "docs/greeting")
+	if err != nil || inspection.PromptVersion == nil || *inspection.PromptVersion != "overridden" {
+		t.Fatalf("inspect imported and overlaid prompt = (%+v, %v)", inspection, err)
+	}
+}
+
+func TestCollectionInputLoadsEmbeddedImportsAndLaterOverride(t *testing.T) {
+	files := fstest.MapFS{
+		"collection.yaml": {Data: []byte("configkit:\n  imports:\n    - path: defaults.yaml\n")},
+		"defaults.yaml":   {Data: []byte("prompts:\n  greeting:\n    version: imported\n    messages:\n      - role: user\n        content: Hello\n    output:\n      format: text\n      validation_mode: none\n")},
+	}
+	filesystem := configkit.NewFilesystem("embedded collection", files)
+	input, err := promptkit.CollectionInput("docs", filesystem.File("collection.yaml"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	input.Filesystem = &configkit.FilesystemContext{FS: &filesystem, Root: "."}
+	engine, err := promptkit.NewEngine(promptkit.Config{Sources: promptkit.ConfigurationSources{
+		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{input}}},
+		Main: &configkit.Input{
+			Source:      configkit.Mapping("later collection override", map[string]any{"prompts": map[string]any{"greeting": map[string]any{"version": "overridden"}}}),
+			Destination: configkit.Keys("collections", "docs"),
+		},
+	}})
+	if err != nil {
+		t.Fatalf("construct engine with embedded collection import: %v", err)
+	}
+	inspection, err := engine.InspectPrompt(context.Background(), "docs/greeting")
+	if err != nil || inspection.PromptVersion == nil || *inspection.PromptVersion != "overridden" {
+		t.Fatalf("inspect imported and overlaid prompt = (%+v, %v)", inspection, err)
+	}
+}
+
 func TestDirectoryInputsSelectsSortedFilesWithRootContext(t *testing.T) {
 	root := t.TempDir()
 	if err := os.Mkdir(filepath.Join(root, "nested"), 0o755); err != nil {

construction_contract_test.go

@@ -1,6 +1,7 @@
 package promptkit_test
 
 import (
+	"bytes"
 	"context"
 	"errors"
 	"io"
@@ -72,11 +73,12 @@ func TestProfileEnvironmentLookupAcceptsNonShellNames(t *testing.T) {
 func TestPublicConstructionWithLocalBackendAndProgrammaticProfile(t *testing.T) {
 	backendID, model := "workstation", "offline-model"
 	prompt := configkit.Input{Source: configkit.Mapping("prompt", map[string]any{
-		"prompts": map[string]any{"hello": map[string]any{"1": map[string]any{
+		"prompts": map[string]any{"hello": map[string]any{
+			"version":         "1",
 			"default_profile": "offline",
 			"messages":        []any{map[string]any{"role": "user", "content": "Hello"}},
 			"output":          map[string]any{"format": "text", "validation_mode": "none"},
-		}}},
+		}},
 	})}
 	client := &fakeLLMClient{response: &promptkit.GenerateResponse{Content: "reply"}}
 	engine, err := promptkit.NewEngine(promptkit.Config{Sources: promptkit.ConfigurationSources{
@@ -105,6 +107,36 @@ func TestPublicConstructionWithLocalBackendAndProgrammaticProfile(t *testing.T)
 	}
 }
 
+func TestFormerCatalogBackendIDsWorkWhenConfigured(t *testing.T) {
+	openRouterID, rakestrawhomeID := promptkit.BackendOpenRouter, promptkit.BackendRakestrawHome
+	openRouterEndpoint, rakestrawhomeEndpoint := "https://openrouter.example/v1", "https://inference.example/v1"
+	model := "configured-model"
+	engine, err := promptkit.NewEngine(promptkit.Config{Sources: promptkit.ConfigurationSources{
+		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{
+			{Source: promptkit.BackendSource("application backends", map[string]promptkit.BackendConfig{
+				openRouterID:    {Endpoint: &openRouterEndpoint},
+				rakestrawhomeID: {Endpoint: &rakestrawhomeEndpoint},
+			})},
+			{Source: promptkit.ProfileSource("application profiles", map[string]promptkit.ProfileConfig{
+				"openrouter-profile":    {Backend: &openRouterID, Model: &model},
+				"rakestrawhome-profile": {Backend: &rakestrawhomeID, Model: &model},
+			})},
+		}}},
+	}})
+	if err != nil {
+		t.Fatalf("construct engine with explicitly configured provider IDs: %v", err)
+	}
+	for profileID, backendID := range map[string]string{
+		"openrouter-profile":    openRouterID,
+		"rakestrawhome-profile": rakestrawhomeID,
+	} {
+		inspection, err := engine.InspectProfile(context.Background(), profileID)
+		if err != nil || inspection.EffectiveModelParams.BackendID != backendID {
+			t.Fatalf("inspect %q = (%+v, %v), want backend %q", profileID, inspection, err, backendID)
+		}
+	}
+}
+
 func TestPublicConstructionCombinesEmbeddedOperatorAndProgrammaticInputs(t *testing.T) {
 	embedded, err := promptkit.FilesystemInputs("embedded defaults", fstest.MapFS{
 		"config/default.yaml": &fstest.MapFile{Data: []byte(`
@@ -114,14 +146,14 @@ profiles:
     model: default-model
 prompts:
   hello:
-    "1":
-      default_profile: application
-      messages:
-        - role: user
-          content: Hello
-      output:
-        format: text
-        validation_mode: none
+    version: "1"
+    default_profile: application
+    messages:
+      - role: user
+        content: Hello
+    output:
+      format: text
+      validation_mode: none
 `)},
 	}, "config")
 	if err != nil {
@@ -189,43 +221,94 @@ func TestPublicConstructionRejectsSuppliedInvalidMainInput(t *testing.T) {
 	}
 }
 
-func TestPublicConstructionCanOverlayMaintainedBackend(t *testing.T) {
-	endpoint := "http://local-openrouter.example/v1"
+func TestPublicConstructionUsesProgrammaticBackendAndProfileSources(t *testing.T) {
+	endpoint, backendID, model := "http://application.example/v1", "application-backend", "synthetic-model"
 	engine, err := promptkit.NewEngine(promptkit.Config{Sources: promptkit.ConfigurationSources{
-		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{{Source: promptkit.BackendSource("operator backend", map[string]promptkit.BackendConfig{
-			promptkit.BackendOpenRouter: {Endpoint: &endpoint},
-		})}}}},
+		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{
+			{Source: promptkit.BackendSource("operator backend", map[string]promptkit.BackendConfig{
+				backendID: {Endpoint: &endpoint},
+			})},
+			{Source: promptkit.ProfileSource("operator profile", map[string]promptkit.ProfileConfig{
+				"application-profile": {Backend: &backendID, Model: &model},
+			})},
+		}}},
 	}})
 	if err != nil {
 		t.Fatalf("construct engine with backend overlay: %v", err)
 	}
-	inspection, err := engine.InspectProfile(context.Background(), "mistral-small-3")
+	inspection, err := engine.InspectProfile(context.Background(), "application-profile")
 	if err != nil {
-		t.Fatalf("inspect catalog profile: %v", err)
+		t.Fatalf("inspect configured profile: %v", err)
 	}
 	if inspection.EffectiveModelParams.Endpoint != endpoint {
 		t.Fatalf("effective endpoint = %q, want %q", inspection.EffectiveModelParams.Endpoint, endpoint)
 	}
 }
 
-func TestPreparationRejectsAmbiguousPromptVersion(t *testing.T) {
-	definition := func(content string) map[string]any {
-		return map[string]any{
-			"messages": []any{map[string]any{"role": "user", "content": content}},
-			"output":   map[string]any{"format": "text", "validation_mode": "none"},
-		}
-	}
+func TestBackendSourceOwnsSmokeTestValuesAndDefersDefaultLookup(t *testing.T) {
+	backendEndpoint := "https://backend.example/v1"
+	defaultProfile := "not-yet-listed"
+	reachabilityEndpoint := " https://probe.example/ready?check=1 "
+	authenticationKind := " OPENROUTER_KEY "
+	authenticationEndpoint := "https://probe.example/key?scope=current"
+	source := promptkit.BackendSource("diagnostic backend", map[string]promptkit.BackendConfig{
+		"local": {
+			Endpoint: &backendEndpoint,
+			SmokeTests: &promptkit.BackendSmokeTestConfig{
+				DefaultProfile: &defaultProfile,
+				Reachability:   &promptkit.ReachabilityProbeConfig{Endpoint: &reachabilityEndpoint},
+				Authentication: &promptkit.AuthenticationProbeConfig{
+					Kind: &authenticationKind, Endpoint: &authenticationEndpoint,
+				},
+			},
+		},
+	})
+	backendEndpoint = "https://mutated.example/v1"
+	defaultProfile = "mutated-profile"
+	reachabilityEndpoint = "https://mutated.example/ready"
+	authenticationKind = "none"
+	authenticationEndpoint = "https://mutated.example/key"
+
 	engine, err := promptkit.NewEngine(promptkit.Config{Sources: promptkit.ConfigurationSources{
-		Main: &configkit.Input{Source: configkit.Mapping("versions", map[string]any{
-			"prompts": map[string]any{"hello": map[string]any{
-				"1": definition("first"), "2": definition("second"),
-			}},
-		})},
+		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{{Source: source}}}},
 	}})
 	if err != nil {
-		t.Fatalf("construct engine: %v", err)
+		t.Fatalf("construct engine with dangling diagnostic default: %v", err)
 	}
-	if result, err := engine.Prepare(context.Background(), promptkit.RunRequest{PromptID: "hello"}); result != nil || !errors.Is(err, promptkit.ErrPromptLoad) {
-		t.Fatalf("ambiguous preparation = (%#v, %v), want ErrPromptLoad", result, err)
+	inspection, err := engine.InspectConfiguration()
+	if err != nil {
+		t.Fatal(err)
+	}
+	var effective bytes.Buffer
+	if err := inspection.WriteEffective(&effective); err != nil {
+		t.Fatal(err)
+	}
+	contents := effective.String()
+	for _, want := range []string{
+		"https://backend.example/v1",
+		"not-yet-listed",
+		"https://probe.example/ready?check=1",
+		"openrouter_key",
+		"https://probe.example/key?scope=current",
+	} {
+		if !strings.Contains(contents, want) {
+			t.Errorf("effective configuration does not contain %q:\n%s", want, contents)
+		}
+	}
+	for _, unwanted := range []string{
+		"mutated.example",
+		"mutated-profile",
+	} {
+		if strings.Contains(contents, unwanted) {
+			t.Errorf("effective configuration unexpectedly contains %q:\n%s", unwanted, contents)
+		}
+	}
+}
+
+func TestPreparationSelectsSinglePromptDefinitionByID(t *testing.T) {
+	engine := newSimpleEngine(t, "selected")
+	prepared, err := engine.Prepare(context.Background(), promptkit.RunRequest{PromptID: "prompt"})
+	if err != nil || prepared == nil || len(prepared.Messages) != 1 || prepared.Messages[0].Content != "selected" {
+		t.Fatalf("prepare prompt by ID = (%+v, %v)", prepared, err)
 	}
 }

consumer_test_helpers_test.go

@@ -63,11 +63,12 @@ func simpleConfig(content string) promptkit.Config {
 			"profiles": map[string]any{"profile": map[string]any{
 				"endpoint": "http://example.test/v1", "model": "model",
 			}},
-			"prompts": map[string]any{"prompt": map[string]any{"1": map[string]any{
+			"prompts": map[string]any{"prompt": map[string]any{
+				"version":         "1",
 				"default_profile": "profile",
 				"messages":        []any{map[string]any{"role": "user", "content": content}},
 				"output":          map[string]any{"format": "text", "validation_mode": "none"},
-			}}},
+			}},
 		})},
 	}}
 }

convert.go

@@ -25,7 +25,6 @@ func toDomainRunRequest(req RunRequest) (domain.RunRequest, error) {
 	}
 	return domain.RunRequest{
 		PromptID:         req.PromptID,
-		PromptVersion:    req.PromptVersion,
 		ProfileID:        req.ProfileID,
 		SessionID:        req.SessionID,
 		APIKey:           req.APIKey,
@@ -73,7 +72,7 @@ func fromDomainPreparedRun(prepared *domain.PreparedRun) *PreparedRun {
 	}
 	return &PreparedRun{
 		PromptID:             prepared.PromptID,
-		PromptVersion:        prepared.PromptVersion,
+		PromptVersion:        copyStringPtr(prepared.PromptVersion),
 		PromptHash:           prepared.PromptHash,
 		SelectedProfileID:    prepared.SelectedProfileID,
 		SelectedBackendID:    prepared.SelectedBackendID,
@@ -100,7 +99,7 @@ func fromDomainRunResult(result *domain.RunResult) *RunResult {
 		RawOutput:            result.RawOutput,
 		Validation:           fromDomainValidationResult(result.Validation),
 		PromptID:             result.PromptID,
-		PromptVersion:        result.PromptVersion,
+		PromptVersion:        copyStringPtr(result.PromptVersion),
 		PromptHash:           result.PromptHash,
 		SessionID:            result.SessionID,
 		RenderedPromptHash:   result.RenderedPromptHash,
@@ -211,6 +210,12 @@ func toDomainExecutionTargetOverride(override *ExecutionTargetOverride) (*domain
 }
 
 func fromDomainExecutionTarget(target domain.ExecutionTarget) ExecutionTarget {
+	return fromDomainExecutionTargetWithOwnedParams(target, copyAnyMap(target.ExtraParams))
+}
+
+// fromDomainExecutionTargetWithOwnedParams projects scalar settings and takes
+// ownership of extraParams, which the caller has already copied.
+func fromDomainExecutionTargetWithOwnedParams(target domain.ExecutionTarget, extraParams map[string]any) ExecutionTarget {
 	return ExecutionTarget{
 		BackendID:       target.BackendID,
 		Endpoint:        target.Endpoint,
@@ -222,7 +227,7 @@ func fromDomainExecutionTarget(target domain.ExecutionTarget) ExecutionTarget {
 		ServiceTier:     target.ServiceTier,
 		ReasoningEffort: target.ReasoningEffort,
 		APIKeyEnv:       target.APIKeyEnv,
-		ExtraParams:     copyAnyMap(target.ExtraParams),
+		ExtraParams:     extraParams,
 	}
 }
 
@@ -252,7 +257,7 @@ func fromDomainPromptInspection(inspection *domain.PromptInspection) *PromptInsp
 	}
 	return &PromptInspection{
 		PromptID:         inspection.PromptID,
-		PromptVersion:    inspection.PromptVersion,
+		PromptVersion:    copyStringPtr(inspection.PromptVersion),
 		PromptHash:       inspection.PromptHash,
 		DefaultProfileID: inspection.DefaultProfileID,
 		Inputs:           inputs,

doc.go

@@ -4,15 +4,16 @@
 // Applications construct an [Engine] with [NewEngine], select ConfigKit
 // sources for prompts, profiles, and backends, and
 // call [Engine.InspectConfiguration], [Engine.InspectPrompt],
-// [Engine.InspectProfile], [Engine.Prepare],
-// [Engine.PrepareExecution], [Engine.Run], or [Engine.RunPrepared]. Concrete
-// registries, repositories, validators, and the built-in OpenAI-compatible
-// client remain internal implementation details.
+// [Engine.InspectRequirements], [Engine.InspectProfile], [Engine.ListProfiles],
+// [Engine.ListPrompts], [Engine.Prepare], [Engine.PrepareExecution],
+// [Engine.Run], or [Engine.RunPrepared]. Concrete registries, repositories,
+// validators, and the built-in OpenAI-compatible client remain internal
+// implementation details.
 //
 // # Concurrency and ownership
 //
 // An Engine supports concurrent InspectConfiguration, InspectPrompt,
-// InspectProfile, Prepare,
+// InspectRequirements, InspectProfile, ListProfiles, ListPrompts, Prepare,
 // PrepareExecution, Run, and RunPrepared calls. Engine-local backend policies
 // bound admitted Run and RunPrepared calls and model generations where
 // configured, while different backend pools and unlimited backends continue
@@ -20,11 +21,12 @@
 // still receive concurrent calls and must be safe for that use.
 //
 // ConfigKit captures the selected configuration when NewEngine constructs an
-// Engine. Prepare,
-// PrepareExecution, and Run copy request maps, slices, pointer values, and
-// JSON-compatible extra parameters before using them. InspectPrompt and
-// InspectProfile return copied inspection values. Returned values and values
-// passed to extension interfaces are likewise isolated from engine state.
+// Engine. Prepare, PrepareExecution, and Run copy request maps, slices, pointer
+// values, and JSON-compatible extra parameters before using them. InspectPrompt,
+// InspectRequirements, and InspectProfile return copied inspection values.
+// ListProfiles and ListPrompts return caller-owned identity slices.
+// Returned values and values passed to extension interfaces are likewise
+// isolated from engine state.
 // Callers own those copies and may mutate them after the call that supplied or
 // returned them. [CapacityError] values are caller-owned and may be mutated
 // without affecting engine state or another error. Immutable [GenerationError]
@@ -58,7 +60,8 @@
 // [ConfigurationSources], [ConfigurationInspection], [BackendConfig],
 // [ProfileConfig], [RunRequest],
 // [ArtifactRef], [ExecutionTargetOverride], [ProfileInspection],
-// [PromptInputDefinition], [PromptInspection], [PreparedExecution],
+// [PromptIdentity], [PromptInputDefinition], [PromptInspection],
+// [RequirementInspectionRequest], [RequirementInspection], [PreparedExecution],
 // [CapacityError], [GenerationError], [RetryExhaustedError], and
 // [ExecutionEvent], do not have stable JSON
 // representations. Direct API keys are nevertheless excluded from JSON for

docs/consumers/configuration-migration.md

@@ -0,0 +1,165 @@
+# Configuration And API Migration
+
+Promptkit no longer installs a provider catalog or selects prompt definitions
+by descriptive version labels. Applications now choose configuration inputs
+explicitly, and execution selects one prompt by its exact ID. This guide
+explains the shape changes and decisions an application must make; it is not an
+automatic migration tool. The [framework format reference](../formats.md) owns
+the current configuration contract, and the root package GoDoc owns exact API
+signatures and errors.
+
+## Select And Compose The Configuration You Need
+
+Supply each backend, profile, prompt, schema, and collection source that the
+application intends to use. Promptkit does not discover directories or install
+provider definitions implicitly. An application may select an explicit
+collection input with `CollectionInput`:
+
+```go
+input, err := promptkit.CollectionInput(
+	"openrouter",
+	configkit.File("config/openrouter.yaml"),
+)
+if err != nil {
+	return err
+}
+engine, err := promptkit.NewEngine(promptkit.Config{
+	Sources: promptkit.ConfigurationSources{
+		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{input}}},
+	},
+})
+```
+
+Collection resource keys are local keys, while their runtime identities are
+qualified. For example, `collections.openrouter.profiles.gemini-flash-latest`
+is selected as `openrouter/gemini-flash-latest`. Stored backend, prompt-default,
+and other resource references must use their exact intended IDs; Promptkit does
+not rewrite references when a source is mounted. Profile `extends` remains a
+sibling local key in the same collection, not a cross-collection reference.
+Review collisions and all references when moving resources into collections.
+
+The root `version` is an optional ConfigKit source header. A collection's
+`release_version` and a prompt's `version` are optional descriptive labels;
+neither selects a resource or changes execution. Preserve a label only when it
+is useful to your application. A formerly version-keyed prompt mapping must be
+reduced to one deliberately chosen definition per prompt ID, with its old label
+retained as prompt metadata if desired. Promptkit cannot choose a winner from a
+consumer's version history.
+
+For example, change a version-keyed definition:
+
+```yaml
+prompts:
+  report:
+    "2.0":
+      messages:
+        - role: user
+          content: Review this report.
+      output:
+        format: text
+        validation_mode: none
+```
+
+to one direct definition. Its optional `version` is only a label:
+
+```yaml
+prompts:
+  report:
+    version: "2.0"
+    messages:
+      - role: user
+        content: Review this report.
+    output:
+      format: text
+      validation_mode: none
+```
+
+## Identity Mapping
+
+The reviewed catalog identities have slash-free profile keys. Their documented
+mapping is:
+
+| Previous identity | Namespaced identity or action |
+| --- | --- |
+| Backend `openrouter` | `openrouter/default` |
+| Backend `rakestrawhome` | `rakestrawhome/default` |
+| Each OpenRouter catalog profile `p` | `openrouter/p`, retaining the exact local key `p` |
+| Profile `rakestrawhome-gemma-4-31b` | `rakestrawhome/rakestrawhome-gemma-4-31b` |
+| Built-in `promptkit-openrouter-standard` | No automatic replacement; optionally define caller profile `openrouter/standard` |
+| Built-in `promptkit-openrouter-auto` | No automatic replacement; optionally define caller profile `openrouter/auto` |
+
+These are conversion examples, not aliases or bundled resources. Mounting old
+`/v3` assets does not update backend references, profile inheritance, prompt
+defaults, or diagnostic defaults inside them. Edit those values to the exact
+qualified IDs you chose.
+
+For example, an optional caller-owned standard profile may extend a selected
+Gemini profile in the same `openrouter` collection:
+
+```yaml
+collections:
+  openrouter:
+    profiles:
+      standard:
+        extends: gemini-flash-latest
+```
+
+An optional auto profile may instead select the exact backend and model values:
+
+```yaml
+collections:
+  openrouter:
+    profiles:
+      auto:
+        backend: openrouter/default
+        model: openrouter/auto
+```
+
+Neither optional profile name is a Promptkit contract. Keep provider model
+strings and settings as selected by the application, including any meaningful
+prefixes. If a backend declares diagnostic defaults, update them to exact
+qualified IDs; an unselected diagnostic default is not automatically made
+resolvable by migration.
+
+## Prompt Selection API
+
+Prompt selection is ID-only. Remove version selectors from calls to `Run`,
+`Prepare`, `PrepareExecution`, `ValidateRequest`, `InspectRequirements`, and
+`SmokeTest`. Remove the `PromptVersion` field from `RunRequest`,
+`RequirementInspectionRequest`, and `SmokeTestRequest`; `InspectPrompt` now
+has the form `InspectPrompt(ctx, promptID)`. For example, select the prompt
+explicitly in the request rather than setting a version selector:
+
+```go
+request := promptkit.RunRequest{
+	PromptID:  "support/report",
+	ProfileID: "support/standard",
+}
+_, err = engine.Run(ctx, request)
+if err != nil {
+	return err
+}
+```
+
+If the former format contained multiple versions under one ID, choose the one
+definition the application should install, and optionally keep its label in
+the prompt's `version` field. That label remains descriptive metadata and is
+reported by inspection or results where applicable; it never chooses the
+definition.
+
+The public inventory APIs can help an operator inspect a captured effective
+configuration: `ListProfiles`, `ListPrompts`, and `ListBackends` return exact
+identities, while `ListNamespaces` and `ListCollections` expose resource-bearing
+namespaces and effective collection declarations. Inventory does not select
+which configuration version the application should deploy.
+
+## Deployment Selection Remains With The Application
+
+Applications decide which checked-in, embedded, operator-supplied, or
+programmatic inputs to compose for each deployment. They also decide when to
+construct a replacement engine after changing those sources. Promptkit does
+not fetch catalog updates, select provider availability, validate upstream
+catalog release status, or automatically migrate arbitrary consumer files.
+The maintained [offline collection example](../../examples/go-library/prepare/main.go)
+shows explicit source selection, local imports, layering, a scoped view, and
+operator inventory without a provider call.

docs/consumers/pkg-promptkit.md

@@ -15,10 +15,30 @@ Import the package as:
 import "gitea.maximumdirect.net/eric/promptkit"
 ```
 
+The maintained [offline preparation example](../../examples/go-library/prepare/main.go)
+demonstrates explicit collection composition and inventory. Applications
+adapting older provider or versioned-prompt configuration can use the
+[configuration migration guide](configuration-migration.md) for the required
+caller-owned choices.
+
 The following Go fragments are illustrative and omit surrounding package,
 import, and error-handling code. Use the maintained examples for complete
 programs.
 
+## Go Compatibility
+
+The `go` directive in the selected release's [module metadata](../../go.mod)
+declares its minimum supported consumer Go version. Maintainers build and
+validate releases with the locally selected Go patch release; the minimum
+does not simply track that patch version.
+
+Successful release validation on the selected patch is sufficient to presume
+support across its Go series, subject to the declared minimum and concrete
+evidence of incompatibility. Specific compatibility concerns are investigated
+as they arise. Minor releases may raise the minimum; patch releases preserve
+it. Release notes explain increases and any required consumer action. See the
+[release policy](../policy/release.md#consumer-minimum-and-release-toolchain).
+
 ## Construct An Engine
 
 Create an engine with [`NewEngine`](../../engine.go). Select each directory
@@ -49,6 +69,34 @@ new engine to observe configuration edits. See the [constructor GoDoc](../../eng
 for the exact public contract and the [framework format reference](../formats.md)
 for definition fields.
 
+### Use Scoped Engine Views
+
+Create a view when an application wants short request IDs to resolve within a
+selected collection:
+
+```go
+scoped, err := engine.WithNamespaces(promptkit.Namespaces{
+	Prompt:  "support",
+	Profile: "support",
+})
+if err != nil { return err }
+
+prepared, err := scoped.Prepare(ctx, promptkit.RunRequest{
+	PromptID:  "answer",
+	ProfileID: "concise",
+})
+```
+
+Execution, preparation, prompt/profile inspection, requirement inspection, and
+smoke diagnostics qualify slashless caller selections with their respective
+namespaces. Already-qualified IDs pass through unchanged; configured defaults
+and references are not rewritten. Each call replaces the view's scope defaults,
+including clearing a scope with an empty field, without changing the receiver
+or rebuilding its captured configuration and execution collaborators.
+Namespace syntax is checked when creating the view; resource existence is
+checked when selected. Configuration inspection remains global. See
+[`WithNamespaces`](../../namespaces.go) for the exact public contract.
+
 ## Supply Embedded Application Defaults
 
 Use `FilesystemInputs` for embedded defaults and `DirectoryInputs` for an
@@ -95,8 +143,8 @@ input := configkit.Input{Source: document}
 ```
 
 `ProfileSource` and `BackendSource` are smaller typed conveniences when null
-is not needed. A caller underlay can overlay catalog backend fields just as it
-can overlay profiles; there is no registration-only backend namespace.
+is not needed. Backend and profile definitions are supplied by the caller;
+there is no registration-only backend namespace.
 
 When configuration or message files change, build and validate a new engine,
 then switch the application to that engine for subsequent work. Existing
@@ -104,6 +152,53 @@ engines and prepared handles retain their captured definitions; schema and
 request artifact resources still follow their runtime lifecycle. Inspection
 does not watch or reload sources automatically.
 
+## Discover Available Resources And Collections
+
+Use [`Engine.ListProfiles`](../../listing.go),
+[`Engine.ListPrompts`](../../listing.go), and
+[`Engine.ListBackends`](../../listing.go) to discover exact identities from the
+engine's final captured configuration. A scoped view filters by its respective
+namespace by default; pass `NamespaceNamed`, `NamespaceUnqualified`, or
+`NamespaceAll` to override that listing filter without changing execution
+scope. Returned IDs remain full identities and can be used for exact selection:
+
+```go
+profiles, err := engine.ListProfiles(ctx)
+if err != nil {
+	return err
+}
+if len(profiles) > 0 {
+	_, err := engine.InspectProfile(ctx, profiles[0])
+	if err != nil {
+		return err
+	}
+}
+prompts, err := engine.ListPrompts(ctx)
+if err != nil {
+	return err
+}
+if len(prompts) > 0 {
+	selected := prompts[0]
+	inspection, err := engine.InspectPrompt(ctx, selected.ID)
+	if err != nil {
+		return err
+	}
+	_ = inspection
+}
+```
+
+Use [`Engine.ListNamespaces`](../../listing.go) to discover resource-bearing
+namespaces across the entire captured configuration, independent of view
+scopes. [`Engine.ListCollections`](../../listing.go) reports effective
+collection declarations, including metadata-only entries; it does not infer
+collection metadata from resource membership or source history.
+
+These lists describe effective membership, not ConfigKit contribution history,
+and do not promise that a profile is ready to execute. Use inspection for
+details and preparation to resolve request resources. The linked method GoDoc
+owns ordering, ownership, concurrency, and error behavior; identifiers may be
+sensitive application data.
+
 ## Inspect The Captured Configuration
 
 Use [`Engine.InspectConfiguration`](../../configuration_inspection.go) for an
@@ -130,6 +225,104 @@ shows backend-completed execution settings for one profile, and `Prepare` or
 `PreparedExecution.Details` shows request-specific rendered messages, inputs,
 and validation resources. None of those views is a substitute for the others.
 
+To review changes between two independently captured configurations, compare
+their inspection views:
+
+```go
+earlier, err := earlierEngine.InspectConfiguration()
+if err != nil {
+	return err
+}
+later, err := candidateEngine.InspectConfiguration()
+if err != nil {
+	return err
+}
+differences, err := earlier.Diff(later)
+if err != nil {
+	return err
+}
+for _, difference := range differences {
+	if difference.HiddenChanged {
+		// Report a protected change without inferring its value.
+	}
+	if difference.Left.Redacted || difference.Right.Redacted {
+		// Apply the application's disclosure policy before presenting snapshots.
+	}
+}
+```
+
+See the [`ConfigurationInspection.Diff` GoDoc](../../configuration_inspection.go)
+and ConfigKit's [v0.8.0 effective-configuration diff guidance](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.8.0/docs/config.md#effective-configuration-diffs)
+for the exact comparison contract. The operation compares only frozen effective
+configuration values: it does not reread external files or compare their
+contents, resolved credential contents, later execution preparation, or
+request-specific overrides. An empty diff is not proof of equivalent execution.
+Records can contain ordinary application data, so use the application's
+disclosure policy when presenting them.
+
+## Run Explicit Smoke Diagnostics
+
+[`Engine.SmokeTest`](../../smoke_diagnostics.go) runs one explicit diagnostic
+using a target resolved from the engine's captured configuration. It does not
+execute the selected application prompt or its inputs, session, artifacts, or
+output schema. Unlike the offline examples and default test suite, calling it
+can contact the selected provider and use configured credentials. It is a
+consumer operation, not an automatic readiness verdict or a release check.
+
+For example, a caller can request the built-in text inference check and treat
+its optional fact as an observation rather than assuming that a nil Go error
+means success:
+
+```go
+report, err := engine.SmokeTest(ctx, promptkit.SmokeTestRequest{
+	Kind:      promptkit.SmokeTestTextInference,
+	ProfileID: profileID,
+	APIKey:    apiKey,
+})
+if err != nil {
+	if report != nil {
+		retainDisclosureSafeSummary(report)
+	}
+	return err
+}
+if report != nil {
+	matched := report.Facts.ExpectedTextMatched
+	switch {
+	case matched == nil:
+		// The comparison was not evaluated or is unknown/inapplicable.
+	case *matched:
+		// The private expected-text comparison matched.
+	default:
+		// It did not match; the operation may still have concluded normally.
+	}
+}
+```
+
+A nil Go error means the diagnostic concluded, not that its finding was
+positive. Fact pointers are tri-state: nil means unknown, not evaluated, or
+inapplicable. Reports contain factual observations and effective settings, not
+generated text or provider bodies; identifiers and settings can still be
+sensitive. The
+[`SmokeTest` GoDoc](../../smoke_diagnostics.go) owns selection precedence,
+exact fields, timeout and retry behavior, supported transports, and disclosure
+details.
+
+Caller cancellation can return both an error and a partial report. Preserve the
+context error identity and inspect any available observations before returning:
+
+```go
+report, err := engine.SmokeTest(ctx, request)
+if report != nil {
+	retainDisclosureSafeSummary(report)
+}
+if err != nil {
+	if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
+		// The report may describe work completed before interruption.
+	}
+	return err
+}
+```
+
 ## Inspect A Prompt Before Preparation
 
 Use [`Engine.InspectPrompt`](../../engine.go) to check one configured prompt's
@@ -137,7 +330,7 @@ declared inputs and output workflow without creating placeholder inputs or
 resolving a profile:
 
 ```go
-inspection, err := engine.InspectPrompt(ctx, "meeting.summary", "")
+inspection, err := engine.InspectPrompt(ctx, "meeting.summary")
 if err != nil {
 	return err
 }
@@ -154,6 +347,85 @@ rendered messages, and use prepared execution when that work must remain tied
 to later execution. The method's [GoDoc](../../engine.go) owns exact fields,
 hash, ownership, and error semantics.
 
+## Inspect Requirements Before Preparation
+
+Use [`Engine.InspectRequirements`](../../requirements.go) when the application
+needs the prompt's recognizable input and caller-variable dependencies for a
+particular context before it has input artifacts. Unlike `InspectPrompt`, it
+also walks captured template syntax and selects a profile identity; unlike
+`Prepare`, it does not load artifacts or render messages.
+
+```go
+requirements, err := engine.InspectRequirements(ctx, promptkit.RequirementInspectionRequest{
+	PromptID: "meeting.summary",
+	Vars:     map[string]string{"audience": "project leads"},
+})
+if err != nil {
+	return err
+}
+
+for _, input := range requirements.Inputs {
+	if input.Kind == promptkit.RequirementRequired {
+		// Plan to bind this input before preparation.
+	}
+	if input.Kind == promptkit.RequirementOptional && input.Explanation != "" {
+		// A recognizable reference may occur only on a known skipped path.
+	}
+}
+for _, variable := range requirements.Variables {
+	if variable.Kind == promptkit.RequirementRequired && !variable.Supplied {
+		// The key is required even though this inspection did not receive it.
+	}
+}
+if !requirements.Complete {
+	// Preserve the partial inventory and account for its discovery issues.
+}
+```
+
+Optional entries can include recognizable inputs and variables found only in
+inactive branches. A missing required variable is reported separately from
+discovery completeness: missing a value used only for direct text substitution
+does not by itself make the inventory incomplete. Conversely, an unresolved
+dependency-bearing branch can make discovery incomplete while retaining known
+conditional entries. Do not treat an empty partial inventory as proof that no
+input bindings are needed. See the method's [GoDoc](../../requirements.go) for
+the exact classifications, supported syntax, ownership, and error contract.
+
+## Validate A Concrete Request
+
+Use [`Engine.ValidateRequest`](../../engine.go) when the application has a
+complete `RunRequest` and needs to know whether that concrete invocation passes
+preparation:
+
+```go
+request := promptkit.RunRequest{
+	PromptID: "meeting.summary",
+	Vars:     map[string]string{"audience": "project leads"},
+	Inputs: map[string]promptkit.ArtifactRef{
+		"note": promptkit.Inline("Synthetic meeting notes"),
+	},
+}
+if err := engine.ValidateRequest(ctx, request); err != nil {
+	return err
+}
+```
+
+Unlike `InspectRequirements`, this checks supplied values, the selected template
+branches, and request bindings through the existing preparation path. It checks
+only this invocation, does not aggregate errors, and loads every supplied input
+according to ordinary preparation behavior, even if a branch does not use it.
+It makes no model call and returns no prepared snapshot, but artifact and schema
+resource I/O and its time and memory costs remain. Success does not certify
+provider acceptance or later execution success. See the method's GoDoc for its
+exact error and context behavior.
+
+Scriptorium can map the returned error to its own diagnostics and exit status.
+Its `validate` and `run` commands should construct equivalent requests for
+equivalent caller inputs so their preparation behavior agrees. Separate
+subprocess calls prepare independently; an opaque `PrepareExecution` handle
+cannot be transferred from `validate` to `run`. Use `PrepareExecution` when one
+process and engine must execute the exact prepared snapshot.
+
 ## Prepare Without Model Execution
 
 [`Engine.Prepare`](../../engine.go) resolves the selected prompt and profile,
@@ -174,8 +446,11 @@ prepared, err := engine.Prepare(ctx, promptkit.RunRequest{
 The maintained
 [offline preparation example](../../examples/go-library/prepare/main.go)
 shows a complete runnable setup with a prompt file, in-memory profile, and
-inline input. Exact request requirements and prepared-result fields belong to
-the [`RunRequest` and `PreparedRun` GoDoc](../../types.go).
+inline input. It demonstrates validation and preparation with the same request
+to make the two operations concrete; this performs preparation twice and is
+illustrative, not a requirement to validate before `Prepare` or `Run`. Exact
+request requirements and prepared-result fields belong to the
+[`RunRequest` and `PreparedRun` GoDoc](../../types.go).
 
 ## Prepare Now And Execute The Same Snapshot Later
 
@@ -362,96 +637,28 @@ are keys in configuration, not registrations. Choose caller underlays in
 fallback-to-operator-to-programmatic order; use `Sources.Main` for one final
 highest-priority input.
 
-Move embedded `id` and `version` fields into keyed `profiles` and `prompts`
-maps; convert `base_profile` to ConfigKit `extends`. IDs and references are
-exact literal keys, without trimming. A supplied zero, false, or empty string
-is now distinguishable from omission; null can clear or suppress an inherited
-field according to the [field table](../formats.md#defaults-and-overrides).
-Maps merge recursively across inheritance and layers. `{}` does not clear an
-inherited map: use null to clear the whole map. At request time, a literal
-`extra_params["extends"]` is ordinary provider data, not an inheritance
-instruction; a nonempty request ExtraParams map replaces configured params.
-Changing a model or backend does not clear unrelated explicit fields, though
-backend-derived defaults are applied after inheritance to the final backend.
-
-Invalid final definitions, including unused ones, now fail `NewEngine`; only
-request-dependent failures remain at preparation or execution. Prompt text
-and static templates are captured at construction, not automatically reloaded
-between runs. Replace the engine to pick up changed definitions or message
-files. The [format reference](../formats.md) owns exact field and presence
-rules; the maintained examples show complete runnable workflows.
+Move embedded IDs into keyed `profiles` and `prompts` maps; each prompt ID now
+contains one installed definition, with any descriptive `version` label inside
+that definition. Convert `base_profile` to ConfigKit `extends`. For the current
+collection identity mapping, ID-only prompt selection, and required
+caller-owned choices, see the
+[configuration migration guide](configuration-migration.md). Exact current
+format, reference, inheritance, and presence semantics belong to the
+[framework format reference](../formats.md). Prompt text and static templates
+are captured at construction, not automatically reloaded between runs. Replace
+the engine to pick up changed definitions or message files.
 
 ### Choose A Profile Ownership Model
 
-Choose the profile source that matches the application's continuity needs:
-
-- Select `promptkit-openrouter-standard` or `promptkit-openrouter-auto` when
-  the maintained literal name is the desired consumer contract. Their current
-  selections are in the [format reference](../formats.md#built-in-profile-catalog).
-- Select an external catalog profile directly when the application accepts that
-  profile's catalog volatility. The selected external inventories are linked
-  from the [format reference](../formats.md#external-profile-inventories).
-- Define a complete application-owned profile with an explicit backend or
-  endpoint, model, and settings when the application owns those choices.
-
-An application profile that inherits an external base follows later changes to
-that base and fails if the base disappears; it is not a frozen copy. Promptkit
-tests the catalog versions selected in its module graph. Independently advancing
-a catalog dependency can remove an inherited base and produce an untested
-combination. Pinning the resolved module graph preserves the embedded data for
-a build, but cannot preserve provider availability. Running binaries neither
-download catalog updates nor automatically replace withdrawn models. See the
-[release policy](../policy/release.md#catalog-profile-compatibility) for the exact
-cross-version guarantees.
-
-### Alias A Built-In Profile
-
-Give an application-owned profile ID a built-in base when prompts should select
-the application ID while inheriting the built-in target. The child can override
-only the setting it owns:
-
-```go
-profile := promptkit.ProfileSource("application profiles", map[string]promptkit.ProfileConfig{
-	"weather-light": {
-		Extends: &standardID,
-		ReasoningEffort: &high,
-	},
-})
-```
-
-Place `profile` in a ConfigKit underlay, with `standardID` set to
-`"promptkit-openrouter-standard"` and `high` to `"high"`. Select
-`weather-light` in a prompt or `RunRequest.ProfileID`; it remains the
-reported selected profile. Definition IDs and inheritance references are exact
-keys. If the base is an external profile, apply the volatility guidance
-above when deciding whether to use an application-owned complete definition
-instead.
-
-### Use The Rakestrawhome Built-In Profile
-
-Set `RAKESTRAWHOME_INFERENCE_API_KEY` in the application environment, then
-select `rakestrawhome-gemma-4-31b` as an ordinary profile ID. For example, a
-prepared result identifies the selected built-in through
-`BackendRakestrawHome`:
-
-```go
-prepared, err := engine.Prepare(ctx, promptkit.RunRequest{
-	PromptID:  "meeting.summary",
-	ProfileID: "rakestrawhome-gemma-4-31b",
-	Inputs:    inputs,
-})
-if err != nil {
-	return err
-}
-if prepared.SelectedBackendID != promptkit.BackendRakestrawHome {
-	return fmt.Errorf("unexpected backend %q", prepared.SelectedBackendID)
-}
-```
-
-The maintained catalog supplies this backend, and callers may overlay its
-effective configuration through a later ConfigKit source. Direct request credentials
-and runtime endpoint overrides remain supported under their ordinary GoDoc and
-format contracts.
+Supply backend and profile definitions through the configuration sources your
+application selects. PromptKit does not install provider catalogs or built-in
+profile inventories; conventional backend ID constants are names only. Define
+the model, endpoint, credentials lookup, and settings that your application
+intends to support. A profile may inherit a sibling profile by its local key in
+the same root or collection mapping; its backend reference uses the exact
+configured identity. Caller-selected source layers determine the final values. The
+[format reference](../formats.md) describes the definition fields and
+composition rules.
 
 ### Inspect A Profile Before Prompt Work
 

docs/development.md

@@ -43,13 +43,13 @@ Before starting work:
 | Root public API | The [architecture policy](policy/architecture.md), [consumer guide](consumers/pkg-promptkit.md), [testing policy](policy/testing.md), and existing GoDoc. |
 | Prompt, profile, or schema formats | The [framework format reference](formats.md), owning parser or validator package, and [documentation policy](policy/documentation.md). |
 | Source loading or validation | The [framework format reference](formats.md), [internal source document](internal/sources.md), and owning package tests. |
-| Maintained external catalogs or built-ins | The [internal source document](internal/sources.md), [framework format reference](formats.md), [testing policy](policy/testing.md), both catalog module repositories, each catalog's release procedure, and the selected module versions in `go.mod`. |
+| Caller-supplied configuration sources | The [internal source document](internal/sources.md), [framework format reference](formats.md), and [testing policy](policy/testing.md). |
 | Model-client behavior | The [OpenAI-compatible integration contract](integrations/openai-compatible-chat.md), [internal model-client document](internal/llm.md), and owning package tests. |
 | Internal package implementation | The [architecture policy](policy/architecture.md), [internal component overview](internal/overview.md), and focused internal document listed for that package. |
 | Tests or test fixtures | The [testing policy](policy/testing.md), owning package, and focused internal document listed by the component overview. |
 | Maintained example | The [preparation](../examples/go-library/prepare/main.go), [execution](../examples/go-library/run/main.go), and [observation](../examples/go-library/observe/main.go) examples, [consumer guide](consumers/pkg-promptkit.md), [framework format reference](formats.md), and [documentation policy](policy/documentation.md). |
 | Documentation | The [documentation policy](policy/documentation.md) and canonical owner of every affected contract. |
-| Licensing, dependencies/catalog updates, copied material, or attribution | The [OSS policy](policy/oss.md), [project grant](../COPYRIGHT), [license texts](../LICENSE), and [attribution entries](oss/attribution.md); inspect the selected upstream source's notices. |
+| Licensing, dependencies, copied material, or attribution | The [OSS policy](policy/oss.md), [project grant](../COPYRIGHT), [license texts](../LICENSE), and [attribution entries](oss/attribution.md); inspect the selected upstream source's notices. |
 | Release preparation or publication, including release notes | The [release policy](policy/release.md), [release procedure](release.md), and [OSS discoverability rules](policy/oss.md#discoverability). |
 
 For cross-cutting changes, follow every applicable row. Do not create
@@ -59,37 +59,43 @@ exist.
 ## Maintainer Validation
 
 For ordinary work, select validation proportionate to the change. Do not repeat
-successful checks for unchanged content merely to create a commit. The full
-release-candidate checks have one executable entry point from the repository root:
+successful checks for unchanged content merely to create a commit. During
+development, run relevant Go tests and vet, format changed Go files, and execute
+the maintained examples when they are affected:
 
 ```sh
-./scripts/release-check.sh
+go test ./...
+go vet ./...
+gofmt -w path/to/changed.go
+python3 scripts/check-examples.py
+git diff --check
 ```
 
-The [script](../scripts/release-check.sh) owns the executable checks:
-race-enabled tests, vet, the three offline consumer examples with semantic output
-assertions, tracked Go formatting, local Markdown links, module/workspace
-hygiene, whitespace, and the credential-pattern scan. It does not publish,
-change files, validate release-note structure, or retire roadmaps. It requires Go,
-Git, a POSIX shell, and Python 3. Tests and examples require no provider
-credentials or live inference calls.
+Release candidates use `./scripts/release.sh VERSION`, which runs the selected
+profile checks and publishes the tag. The [release procedure](release.md)
+describes its requirements and recovery. For an optional diagnostic of a
+committed candidate without publication, run `./scripts/releasekit.sh check
+VERSION`; this is not a required pre-publication step.
 
-The script can run on intended uncommitted changes during development.
-Formatting and documentation checks use tracked files; stage intended new
-files before final validation so those checks include them. The release
-procedure separately enforces a clean, committed candidate.
+The standalone `python3 scripts/check-examples.py` command checks semantic
+expectations for the three offline consumer examples. The focused
+`python3 scripts/test-release.py` command exercises the release tooling against
+disposable local repositories; use it when changing that tooling, not as a
+recurring release gate. Tests and examples require no provider credentials or
+live inference calls.
+
+Ordinary validation can run on intended uncommitted work. Release validation
+uses committed candidate contents and the selected local Go installation.
 
 ### Change Review
 
 Inspect `git status --short --untracked-files=all` and the complete diff before
 accepting a change. Reject unintended files, credentials, private data,
 generated binaries, test output, downloaded assets, and template residue.
-The automated credential scan does not replace review of the actual change.
 
-For releases, follow the [release procedure](release.md). Its publication
-command runs the full local checks once on the final committed candidate and
-automates release-note structure and Git checks. Do not repeat ordinary change
-review as a release sign-off. Roadmap retirement remains preparation housekeeping.
+For releases, follow the [release procedure](release.md). Do not repeat its
+candidate checks as a separate sign-off. Roadmap retirement remains preparation
+housekeeping.
 
 Follow the [agent commit policy](policy/agents.md#git-commit-policy) for local
 commits. Ordinary commits may leave unrelated work in the workspace; preserve

docs/formats.md

@@ -10,12 +10,14 @@ owns outbound wire behavior. [ConfigKit](https://gitea.maximumdirect.net/eric/Co
 owns the generic YAML grammar, imports, layering, inheritance, and diagnostics.
 This reference describes what Promptkit does with the final effective values.
 
-A configuration document has keyed top-level `backends`, `profiles`, and
-`prompts` mappings. Their keys are literal IDs, not filename-derived identities.
-Prompt versions are a second keyed mapping. Keys and references must be
-nonblank and remain exact: Promptkit does not trim or re-key them. Old embedded
-`id`, `version`, and `base_profile` fields are invalid. Unknown fields are
-errors.
+A configuration document may contain keyed top-level `backends`, `profiles`,
+and `prompts` mappings, plus a `collections` mapping of namespaced resource
+groups. Resource keys are literal IDs, not filename-derived identities. Each
+prompt ID maps directly to one definition; an optional `version` string is
+descriptive metadata, not a selection key. Keys and references must be nonblank
+and remain exact: Promptkit does not trim or re-key them. Old embedded `id` and
+`base_profile` fields are invalid. Unknown fields are errors. Promptkit installs
+no provider or profile catalog; callers select the definitions they need.
 
 ```yaml
 backends:
@@ -28,16 +30,74 @@ profiles:
     model: example-model
 prompts:
   meeting.summary:
-    "1.0.0":
-      default_profile: local-summary
-      messages:
-        - role: user
-          content: Summarize this note.
-      output:
-        format: text
-        validation_mode: none
+    version: "1.0.0"
+    default_profile: local-summary
+    messages:
+      - role: user
+        content: Summarize this note.
+    output:
+      format: text
+      validation_mode: none
+collections:
+  support:
+    release_version: "1.4.0"
+    backends:
+      offline:
+        endpoint: https://example.invalid/v1
+    profiles:
+      base:
+        backend: support/offline
+        model: offline-model
+      fast:
+        extends: base
+        timeout_seconds: 30
+    prompts:
+      answer:
+        default_profile: support/fast
+        messages:
+          - role: user
+            content: Answer the selected caller input.
+        output:
+          format: text
+          validation_mode: none
 ```
 
+## Source Headers, Collections, And Resource IDs
+
+An input may omit a source header. When present, the source-root `version` is
+reserved for ConfigKit's specification header and accepts only the exact string
+`"1"` or strict decimal integer `1`; null and other values are invalid. This
+header is distinct from a prompt's nested `version` label and a collection's
+`release_version`. ConfigKit checks and consumes accepted headers on non-main
+inputs; a declaration on the main input remains visible in explicit
+configuration inspection. Headerless inputs still undergo ordinary final-value
+validation. ConfigKit owns generic import and source-history behavior.
+
+The root resource mappings contain unqualified IDs. Each `collections` entry
+has a namespace key and may contain `release_version` plus the same three
+resource mappings. Collection resource keys are local keys; their runtime IDs
+are `<namespace>/<local-key>`. Root and collection keys may be the same. A
+namespace and local key must be nonblank and slash-free, and references must
+name their intended exact ID; mounting a source does not rewrite references.
+For example, the `support/fast` profile above stores `support/offline` as its
+backend ID. In `collections.support.profiles.fast`, ConfigKit `extends: base`
+refers to a sibling profile in that same mapping. It is not a qualified or
+cross-collection reference.
+
+`release_version` and prompt `version` are optional opaque labels. Absent or
+null means no label; an explicitly empty string is retained as a declared
+label. Neither label selects a resource or changes execution. Runtime lookups
+use the captured effective resource indexes. `InspectConfiguration` is an
+explicit operator view of effective settings and provenance; source history is
+not a second runtime resolver, and the retained effective shape is not flattened
+or rewritten into those indexes.
+
+For examples of explicitly selecting native collection inputs and inspecting
+inventories, see the [consumer guide](consumers/pkg-promptkit.md) and its
+[maintained preparation example](../examples/go-library/prepare/main.go). For
+breaking identity and prompt-selection changes, see the
+[configuration migration guide](consumers/configuration-migration.md).
+
 Every effective backend, profile, and prompt definition is validated when
 `NewEngine` constructs the engine, even if it is never selected. A profile may
 be partial: an endpoint and model need only be complete after request overrides
@@ -51,36 +111,37 @@ message files on ordinary runs; construct a new engine to observe edits.
 Schema and request artifact reads still happen during preparation. Use
 `InspectConfiguration` for an explicit effective-configuration or provenance
 report, `InspectProfile` for backend-completed profile settings, and preparation
-for request-specific rendered details.
+for request-specific rendered details. For identity discovery before inspection,
+see the consumer guide's [resource and collection listing](consumers/pkg-promptkit.md#discover-available-resources-and-collections).
 
 ## Prompt Definitions
 
-The `prompts` mapping selects a literal prompt ID, then a string version key:
+The `prompts` mapping selects a literal prompt ID whose value is the definition:
 
 ```yaml
 prompts:
   meeting.summary:
-    "1.0.0":
-      default_profile: local-summary
-      description: Summarize a synthetic meeting note.
-      session_id: '{{.session}}'
-      inputs:
-        - name: note
-          required: true
-          content_type: text/plain
-          description: Meeting note to summarize.
-      messages:
-        - role: system
-          content: Return a concise summary.
-          cache_control:
-            type: ephemeral
-            ttl: 1h
-        - role: user
-          content_file: ./summary.user.md
-      output:
-        format: markdown
-        validation_mode: basic
-        repair_attempts: 0
+    version: "1.0.0"
+    default_profile: local-summary
+    description: Summarize a synthetic meeting note.
+    session_id: '{{.session}}'
+    inputs:
+      - name: note
+        required: true
+        content_type: text/plain
+        description: Meeting note to summarize.
+    messages:
+      - role: system
+        content: Return a concise summary.
+        cache_control:
+          type: ephemeral
+          ttl: 1h
+      - role: user
+        content_file: ./summary.user.md
+    output:
+      format: markdown
+      validation_mode: basic
+      repair_attempts: 0
 ```
 
 `messages` must be nonempty and `output` must be a valid mapping. Optional
@@ -88,9 +149,8 @@ prompts:
 fields may be absent or cleared with null where appropriate. A null whole
 definition, required role, output format, or validation mode is invalid.
 `required` and `repair_attempts` default to false and zero, respectively, and
-are not nullable. A request that omits a prompt version succeeds only if that
-prompt ID has exactly one effective version. `InspectPrompt` selects from the
-same captured definitions without rendering or resolving a profile.
+are not nullable. `InspectPrompt` selects the same captured definition without
+rendering or resolving a profile.
 
 ### Inputs
 
@@ -124,6 +184,12 @@ Optional `session_id` uses the same template variables and input helper. Its
 rendered value is trimmed, omitted if empty, and limited to 256 Unicode code
 points. A nonblank direct request session ID bypasses the template.
 
+`InspectRequirements` can enumerate recognizable dependencies from captured
+templates before artifact content is available. Its conservative syntax
+coverage does not change template validity or rendering; see the [consumer
+guide](consumers/pkg-promptkit.md#inspect-requirements-before-preparation) and
+the method's [GoDoc](../requirements.go) for that inspection boundary.
+
 ### Cache Control
 
 Optional `cache_control` has required `type: ephemeral` and optional `ttl`,
@@ -149,28 +215,64 @@ last candidate and its failed validation result. Operational errors remain
 errors. A request-level `OutputContract` replaces the whole configured one,
 not individual fields; an empty request format defaults to `text`.
 
-## Built-In Backends
+## Backend Definitions
 
-The selected catalog modules contribute these backend definitions as the
-earliest underlay. Their settings can be overlaid by caller sources; these IDs
-are not reserved against configuration changes.
-
-| ID | Catalog endpoint | API-key environment name | Active generation limit |
-| --- | --- | --- | ---: |
-| `openrouter` | `https://openrouter.ai/api/v1` | `OPENROUTER_API_KEY` | 16 |
-| `rakestrawhome` | `https://inference.ai.rakestrawhome.com/v1` | `RAKESTRAWHOME_INFERENCE_API_KEY` | 4 |
+Backend definitions are supplied through caller-selected configuration
+sources. The conventional backend IDs are names only; PromptKit does not
+install definitions for them.
 
 A backend definition may have `endpoint`, `api_key_env`,
-`concurrency_limit`, `queue_capacity`, and `extra_params`. The final endpoint
-is required and must be an absolute HTTP(S) URL with a host, no user
-information, query, or fragment. An omitted or null API-key environment name
-means no lookup. Omitted/null concurrency is zero (unlimited); a supplied
+`concurrency_limit`, `queue_capacity`, `extra_params`, and `smoke_tests`. The
+final endpoint is required and must be an absolute HTTP(S) URL with a host, no
+user information, query, or fragment. An omitted or null API-key environment
+name means no lookup. Omitted/null concurrency is zero (unlimited); a supplied
 negative value is invalid. For positive concurrency, omitted/null queue
 capacity defaults to 1024. An explicit queue capacity, including zero,
 requires positive concurrency and must be nonnegative. Unlimited concurrency
 has no queue. Provider maps contain JSON-compatible values; null entries are
 ordinary JSON null. Unknown fields, including a raw `api_key`, fail.
 
+`smoke_tests` is optional backend metadata for explicit diagnostic operations.
+It may contain `default_profile`, `reachability`, and `authentication`:
+
+```yaml
+backends:
+  openrouter:
+    smoke_tests:
+      default_profile: application-profile
+      reachability:
+        endpoint: https://status.example/ready?check=1
+      authentication:
+        kind: openrouter_key
+        endpoint: https://openrouter.ai/api/v1/key
+```
+
+An omitted or null `smoke_tests` block disables these metadata defaults.
+`default_profile` is preserved as an exact, nonblank profile ID; its existence
+is checked only if an inference diagnostic selects that default. Omitted/null
+`default_profile` means there is no inference default. Omitted/null
+`reachability` or its endpoint uses the effective backend endpoint. An explicit
+reachability endpoint is trimmed and must be an absolute HTTP(S) URL with a
+host; unlike the backend base endpoint, its path and query are allowed. Null
+means fallback, while an explicit blank value is invalid.
+
+Omitted/null `authentication` means no authentication adapter is declared. A
+non-null object requires `kind`, which is trimmed and case-normalized; the
+recognized values are `none` and `openrouter_key`. Its omitted/null endpoint
+uses the adapter's backend-relative destination (`openrouter_key` appends
+`/key` to the effective backend base); an explicit endpoint follows the same
+full-URL rules as reachability. `none` declares authentication inapplicable.
+These values are configuration only: engine construction does not contact a
+backend.
+
+These fields are resolved through the ordinary ConfigKit source layers before
+Promptkit validates the final effective values. A higher-priority mapping can
+override individual nested fields; an explicit null can clear the whole
+`smoke_tests` block or one of its nested objects. An endpoint set to null uses
+its documented fallback, while an explicit blank endpoint is invalid. The
+metadata does not change ordinary generation credential requirements or
+provider settings.
+
 ## Profile Definitions
 
 Profiles are keyed by literal ID and may inherit a named parent with
@@ -231,57 +333,36 @@ does not disable the caller context or HTTP transport timeout.
 
 ### Source And Profile Precedence
 
-`NewEngine` composes catalog definitions first, Promptkit-owned definitions
-next, then caller underlays in their given order, with an optional main input
-last. Later tiers overlay earlier ones. Inputs within one underlay group are
-strictly composed: conflicting contributions are errors, not priority
-signals. The directory helpers discover `.yaml` and `.yml` files recursively
+`NewEngine` composes caller underlays in their given order, followed by an
+optional main input. Later layers overlay earlier ones. Inputs within one
+underlay group are strictly composed: conflicting contributions are errors,
+not priority signals. The directory helpers discover `.yaml` and `.yml` files recursively
 in sorted order, but that order does not give one file higher precedence.
 An explicitly selected missing/unreadable root fails; an empty root contributes
 nothing. Imports are disabled by these helpers unless the caller enables them
 on an input. Single files can use ConfigKit inputs directly.
 
-Backends, profiles, and prompts all follow these same source rules. A later
-profile or backend can change individual fields of a lower definition. A
-request `ProfileID` takes precedence over a prompt `default_profile`; if
+Root backends, profiles, and prompts, as well as collection declarations and
+their resource mappings, follow these same source rules. `CollectionInput`
+mounts one explicitly selected source at a collection destination and enables
+ConfigKit imports for that input; it does not discover or select sources.
+A later profile or backend can change individual fields of a lower definition.
+A request `ProfileID` takes precedence over a prompt `default_profile`; if
 neither is selected, preparation fails. Exact profile inspection selects one
 explicit ID and does not consult a prompt default.
 
 ### Profile Inheritance
 
 ConfigKit resolves `extends` on effective profile definitions. One profile
-may inherit another keyed profile; presence, explicit null, and recursively
-merged maps determine the final fields. References are literal IDs, including
-IDs containing punctuation. There is no Promptkit-specific depth limit or
-second base-chain resolver. Missing references and cycles fail at construction.
-For generic inheritance and layer mechanics, consult
+may inherit a sibling profile by local key in the same root or collection
+mapping; collection inheritance cannot cross namespaces. Presence, explicit
+null, and recursively merged maps determine the final fields. Other resource
+references are exact IDs and use their qualified form when they select a
+collection resource. There is no Promptkit-specific depth limit or second
+base-chain resolver. Missing references and cycles fail at construction. For
+generic inheritance and layer mechanics, consult
 [ConfigKit](https://gitea.maximumdirect.net/eric/ConfigKit).
 
-## Built-In Profile Catalog
-
-Promptkit contributes two opt-in definitions; neither is selected by default:
-
-| ID | Current definition |
-| --- | --- |
-| `promptkit-openrouter-standard` | Extends the selected OpenRouter catalog's `gemini-flash-latest` profile. |
-| `promptkit-openrouter-auto` | Selects backend `openrouter` and model `openrouter/auto`. |
-
-Select one through request `ProfileID` or prompt `default_profile`.
-Caller layers may overlay these definitions or their catalog bases. The
-[release policy](policy/release.md#catalog-profile-compatibility) owns their
-cross-version compatibility boundary.
-
-## External Profile Inventories
-
-The selected catalog modules, not this document, own their profile inventories:
-
-- [OpenRouter catalog v3.20260930.0 profiles](https://gitea.maximumdirect.net/eric/promptkit-backend-openrouter/src/tag/v3.20260930.0/catalog/profiles)
-- [Rakestrawhome catalog v3.20260930.0 profiles](https://gitea.maximumdirect.net/eric/promptkit-backend-rakestrawhome/src/tag/v3.20260930.0/catalog/profiles)
-
-These are tested local data, not a promise of live provider availability.
-The [release policy](policy/release.md#catalog-profile-compatibility) owns
-the compatibility boundary.
-
 ## Schemas
 
 Schemas are JSON documents selected by a prompt or request `schema_path`.

docs/integrations/openai-compatible-chat.md

@@ -45,6 +45,45 @@ precedence over the backend default. Only the name reaches prepared metadata;
 the environment value is read just before the provider call and is never added
 to the JSON body.
 
+## Explicit Smoke Diagnostics
+
+Promptkit's explicit smoke diagnostics are separate consumer operations; they
+are not part of ordinary `Run`, the offline examples, or release validation.
+With the built-in client, inference diagnostics use the same configured client
+and `/chat/completions` request as generation. Their content cases are private
+to Promptkit and are not application prompt, schema, or provider protocol
+extensions. The public
+[`Engine.SmokeTest` GoDoc](../../smoke_diagnostics.go) owns request selection,
+report facts, and injected-client behavior.
+
+HTTP-only diagnostics use the configured built-in HTTP client. Reachability is
+one unauthenticated `GET` to the selected diagnostic URL; an observed response
+counts as reachable even when its status is non-2xx. Authentication behavior
+is selected from backend metadata, not inferred from the host. The
+`openrouter_key` adapter makes one `GET` to `/key` relative to the effective
+backend base, unless configuration supplies a full diagnostic endpoint (see
+the [backend format reference](../formats.md#backend-definitions)). It may send
+the available bearer credential, but can dispatch without one. A 401 is
+recognized as rejection. A 200 is recognized as acceptance only when its JSON
+object has a `data` object containing string `label`, Boolean `is_free_tier`,
+and numeric `usage`; unrelated fields and account limits are ignored. This is
+only a minimal identifying subset of OpenRouter's documented
+[current-key response](https://github.com/OpenRouterTeam/docs/blob/main/api_reference/limits.mdx#checking-your-limits),
+not validation of the full account document. Other statuses and unrecognized
+200 responses do not establish acceptance.
+
+Diagnostic HTTP evidence describes the last request observed at Promptkit's
+RoundTripper boundary and any response associated with it. It includes the
+selected destination without URL user information, response status, and
+credential presence when observed. Redirects can change the last observed
+destination or strip credentials. This evidence does not prove that bytes
+reached a peer or reveal dispatch hidden inside a custom transport. Diagnostic
+reports do not retain headers, credentials, provider
+bodies, or generated text. A consumer-injected `LLMClient` can support inference
+diagnostics, but does not establish HTTP status, destination, reachability, or
+upstream credential-supply facts; Promptkit does not fall back to a built-in
+transport for HTTP-only diagnostics.
+
 ## Request Body
 
 The request body always contains `model` and `messages`. The execution
@@ -78,9 +117,8 @@ The client conditionally includes:
 
 The engine resolves backend, profile, and request extra-parameter maps by
 whole-map replacement rather than key merging. The resulting effective map is
-then merged directly into the top-level body after JSON serialization is
-verified. Empty keys and collisions with these reserved fields are rejected
-before any provider call:
+merged into the top-level body. Empty keys, values that cannot be encoded, and
+collisions with these reserved fields are rejected before any provider call:
 
 - `model`
 - `session_id`

docs/internal/capacity.md

@@ -88,6 +88,17 @@ release, including canceled acquisition without dispatch. A retry wait holds
 the logical admission lease but no active permit. Observer callbacks must not
 block on work that requires the same run's admission slot.
 
+## Smoke-Test Capacity
+
+The engine's smoke tester shares this manager and generation coordinator with
+the ordinary runner. Inference diagnostics reserve the same logical admission
+slot and acquire the same backend-scoped active permits for actual model
+attempts, including retries. They therefore participate in the same configured
+backend limits as `Run`. Reachability and authentication HTTP probes do not
+enter generation admission or consume active permits. The public
+[`Engine.SmokeTest` GoDoc](../../smoke_diagnostics.go) owns the caller-visible
+operation and injected-client limits.
+
 ## Cancellation And Release
 
 Admission checks the caller context before reserving a slot. A call canceled
@@ -127,4 +138,7 @@ cover shared and independent backend pools during retry and repair. The
 own the public prepared-capacity boundary. The
 [root error-boundary tests](../../errors_internal_test.go) own preservation of
 the public generation category and context identity when generation is
-canceled.
+canceled. The assembled
+[smoke diagnostic contract tests](../../smoke_integration_contract_test.go)
+verify that inference diagnostics share the engine's Run admission and recover
+capacity after cancellation or failure.

docs/internal/generation.md

@@ -41,9 +41,22 @@ original error chain. This keeps injected attempt classifications consistent
 with terminal observations without parsing diagnostic text or retrying injected
 clients.
 
+The diagnostic path uses the same private attempt and retry implementation as
+ordinary generation. It retains invocation-local transport, response,
+generation, usage, capacity-wait, and retry-delay evidence before normal
+result-discard and cancellation checks. Built-in preparation also supplies its
+frozen request URL to the evidence path before attempts begin; injected
+generation has no equivalent HTTP destination. This evidence is returned to
+diagnostic orchestration; it is not added to public `ExecutionEvent` values or ordinary
+observer accounting. The [model-client document](llm.md) describes the
+transport-observation boundary, and the root
+[`SmokeTestReport` GoDoc](../../smoke_diagnostics.go) owns report semantics.
+
 Focused coordinator tests use controlled transport and wait functions. They
 cover eligibility, exhaustion, cancellation, backoff, request freezing, permit
-release, and the injected-client path. The capacity manager tests own permit
+release, and the injected-client path. The
+[evidence tests](../../internal/generation/evidence_test.go) own diagnostic
+attempt retention and retry evidence. The capacity manager tests own permit
 acquisition and idempotent release. Public
 [integration tests](../../reliable_execution_contract_test.go) cover retry,
 repair, observation, frozen prepared execution, and shared-backend behavior

docs/internal/llm.md

@@ -34,9 +34,13 @@ resolved request target may supply the endpoint. Generation preparation then:
 1. validates shared execution-setting invariants and the final selected base
    endpoint;
 2. maps the internal request into the OpenAI-compatible chat payload;
-3. validates and merges extra parameters;
+3. checks extra-parameter keys against empty and reserved names, then merges
+   their values into the payload;
 4. composes `/chat/completions` through parsed URL path operations;
-5. resolves authentication and freezes the URL, body, and optional credential.
+5. encodes the complete body once on success. If encoding fails, extra values
+   are checked individually to retain invalid-request classification; otherwise
+   the complete-request failure remains a request failure;
+6. resolves authentication and freezes the URL, body, and optional credential.
 
 Each execution of that prepared request creates a fresh HTTP request, body
 reader, and attempt timeout context. It closes the response body and returns
@@ -55,6 +59,33 @@ This client does not schedule retries; the [generation coordinator](generation.m
 does so around its prepared attempts. The client has no tool-call support,
 provider catalog, inbound HTTP behavior, or durable session store.
 
+## Diagnostic HTTP Evidence
+
+Built-in diagnostics wrap the selected HTTP client's `RoundTripper` for one
+invocation using a shallow client copy, preserving its timeout, redirect policy,
+cookie jar, and underlying transport without mutating the configured client.
+Evidence distinguishes a diagnostic dispatch invocation from an observed
+request and response. A newly observed request replaces the previous
+destination-specific response evidence, so redirects retain only the last
+observed hop. A response is recorded before envelope decoding or later context
+checks can discard a generation result.
+
+The collector keeps only the last observed destination (without URL user
+information), status, credential-presence, response-availability, decoded
+generation, and presence-aware usage facts needed by the diagnostic. It does
+not retain headers, credentials, raw request or response bodies, or a redirect
+trace. These are observations at Promptkit's RoundTripper boundary, not proof
+that bytes reached a peer or that a custom transport did no hidden dispatch.
+Reachability and named authentication probes use the same configured built-in
+client but discard their response bodies after local recognition. The
+[integration contract](../integrations/openai-compatible-chat.md#explicit-smoke-diagnostics)
+owns their observable HTTP semantics.
+
+An injected `LLMClient` does not pass through this HTTP boundary. Its returned
+response can establish response and inference facts, but not an HTTP
+destination, status, reachability, or upstream credential-supply fact. The
+facade does not silently install a built-in transport for those diagnostics.
+
 ## Prepared Generation
 
 For [`RunPrepared`](../../engine.go), the runner supplies the model client with
@@ -133,7 +164,10 @@ own configuration, client cloning, deterministic deadline precedence,
 authentication, request and response mapping, malformed data, error identity,
 cancellation, endpoint selection and composition, pre-transport rejection, and
 bounded single-document successful-response framing, closure, and
-response-body suppression. The focused
+response-body suppression. The [HTTP evidence tests](../../internal/llm/http_evidence_test.go)
+own invocation-local last-hop request/response facts, while the
+[prepared-generation evidence tests](../../internal/llm/prepared_generation_evidence_test.go)
+own retention across decoding and cancellation. The focused
 [provider HTTP error tests](../../internal/llm/provider_http_error_test.go)
 own envelope parsing, normalization, and bounded-reader cases; their
 [transport tests](../../internal/llm/provider_http_error_transport_test.go)

docs/internal/observation.md

@@ -23,6 +23,10 @@ callback. The caller supplies normalized failure metadata; the recorder never
 parses an error string or receives provider bodies, credentials, headers, or
 other content. Events are values with no mutable containers. Callback panics
 propagate to the caller.
+Resolved prompt and profile IDs are the exact runtime identities selected for
+the invocation, including namespace qualification when supplied by an engine
+view. A prompt's optional version label is descriptive metadata, not a
+selection key.
 Per-operation callbacks are ordered and synchronous; different operations may
 invoke the same callback concurrently. The recorder marks each measured phase's
 end before delivery, so callback work does not inflate provider duration.
@@ -41,6 +45,11 @@ attempts above the first in a generation, and repair generations with at least
 one dispatch. A terminal event is an aggregate and must not be added to its
 attempt events.
 
+Smoke diagnostics mask inherited execution-recorder state while invoking
+generation or HTTP collaborators. Their private attempt evidence is assembled
+into a `SmokeTestReport`; it does not create ordinary run events or enter an
+enclosing run's observation totals.
+
 The [recorder tests](../../internal/observation/recorder_test.go) own usage
 presence, phase sums, event ordering, empty-run accounting, identity snapshots,
 and callback panic behavior. The [generation coordinator](generation.md) owns

docs/internal/overview.md

@@ -11,28 +11,27 @@ contributor workflow and validation.
 
 | Component | Implemented responsibility | References |
 | --- | --- | --- |
-| Root `promptkit` package | Provides the supported engine facade, ConfigKit source helpers, profile and backend mapping conveniences, injection options, public requests and results, explicit inspection, observation values, opaque prepared-execution handles, value conversion, redacted formatting, and typed capacity and generation error mapping. | [Package GoDoc](../../doc.go), [observations](../../observations.go), [prepared execution](../../prepared_execution.go), [backend API](../../backends.go), [engine facade](../../engine.go) |
-| `examples/go-library/prepare` | Demonstrates offline preparation and explicit configuration inspection with a prompt file, programmatic profile, and inline input. It is not a public library package. | [Example program](../../examples/go-library/prepare/main.go) |
+| Root `promptkit` package | Provides the supported engine facade, ConfigKit source helpers, collection and resource mapping conveniences, injection options, public requests and results, prompt/profile/requirement inspection and identity inventories, concrete-request validation, explicit smoke diagnostics, observation values, opaque prepared-execution handles, value conversion, redacted formatting, and typed capacity and generation error mapping. | [Package GoDoc](../../doc.go), [observations](../../observations.go), [prepared execution](../../prepared_execution.go), [backend API](../../backends.go), [engine facade](../../engine.go), [smoke diagnostics](../../smoke_diagnostics.go), [identity listing](../../listing.go), [requirement facade](../../requirements.go) |
+| `examples/go-library/prepare` | Demonstrates offline preparation from two explicitly selected synthetic collections, source-relative imported content, a scoped view, filtered listings, and operator inventory. It is not a public library package. | [Example program](../../examples/go-library/prepare/main.go), [collection inputs](../../examples/go-library/prepare/collections/support/collection.yaml) |
 | `examples/go-library/run` | Demonstrates an offline downstream consumer using a prompt file, programmatic profile, inline input, an injected deterministic model client, and `Run`. It is not a public library package. | [Example program](../../examples/go-library/run/main.go) |
 | `examples/go-library/observe` | Demonstrates offline built-in HTTP retry and synchronous metadata observation across structured proposal and assessment runs using embedded sources, two profiles on one finite backend, and an application decision. It is not a public library package. | [Example program](../../examples/go-library/observe/main.go) |
-| `internal/backend` | Holds a defensive, immutable lookup and capacity-policy index for final backend definitions validated by the configuration adapter. | [Backend registry](../../internal/backend/registry.go) |
-| `internal/catalog` | Selects released keyed catalog assets and PromptKit-owned profile definitions as ConfigKit underlays; effective validation belongs to the configuration loader. | [Catalog adapter](../../internal/catalog/catalog.go), [internal sources](sources.md#profiles-and-built-ins) |
-| `internal/configuration` | Loads keyed backend, profile, and prompt configuration through ConfigKit; records effective field presence, validates final values, captures indexed prompt definitions and referenced message content, constructs backend and presence-aware profile snapshots, and retains an explicit read-only inspection view. | [Typed loader](../../internal/configuration/load.go), [internal sources](sources.md#typed-configuration-loading) |
+| `internal/backend` | Holds a defensive, immutable lookup of final backend definitions, including diagnostic metadata, plus capacity policies validated by the configuration adapter. | [Backend registry](../../internal/backend/registry.go) |
+| `internal/configuration` | Loads root and namespaced collection resources through ConfigKit; records effective field presence, validates final values including exact references and optional diagnostic metadata, captures indexed prompt definitions and source-relative message content, compiled templates, input metadata snapshots, sorted backend/profile/prompt identities, resource namespace sets, effective collection declarations, backend and presence-aware profile snapshots, and the unchanged read-only inspection view. | [Typed loader](../../internal/configuration/load.go), [identity listing](../../internal/configuration/listing.go), [internal sources](sources.md#typed-configuration-loading) |
 | `internal/capacity` | Owns engine-local bounded execution admission and FIFO model-generation permits for limited backend IDs, including cancellation-safe waiter removal and client wrapping. | [Internal capacity management](capacity.md) |
-| `internal/domain` | Defines internal framework values for requests, artifacts, prompt definitions, profiles, execution targets, rendering, generation, and validation, and owns source-neutral invariants for shared execution settings, OpenAI-compatible base endpoints, session identifiers, and output contracts. Source parsing, required fields, other source-specific normalization, defaulting, and boundary-specific error classification remain with their callers. | [Domain declarations](../../internal/domain/domain.go), [endpoint invariant](../../internal/domain/endpoint.go) |
-| `internal/engine` | Assembles selected catalog and caller configuration into one snapshot, then constructs capacity, rendering, validation, generation, repair, and the use-case runner for each engine. | [Engine assembly](../../internal/engine/engine.go), [internal sources](sources.md#profiles-and-built-ins), [internal runner](runner.md) |
-| `internal/generation` | Coordinates frozen built-in HTTP attempts and one-shot injected calls through active backend permits, including bounded status retries, cancellable backoff, and attempt observations. | [Internal generation coordination](generation.md) |
+| `internal/domain` | Defines internal framework values for requests, artifacts, prompt definitions, requirement inspection, profiles, execution targets, rendering, generation, validation, and source-neutral smoke diagnostics, and owns source-neutral invariants for shared execution settings, OpenAI-compatible base endpoints, session identifiers, output contracts, and resource-identity syntax and qualification. Source parsing, required fields, other source-specific normalization, defaulting, and boundary-specific error classification remain with their callers. | [Domain declarations](../../internal/domain/domain.go), [requirement values](../../internal/domain/requirements.go), [endpoint invariant](../../internal/domain/endpoint.go) |
+| `internal/engine` | Assembles caller-selected configuration into one snapshot, then constructs shared capacity, rendering, validation, generation, repair, the ordinary runner, and the smoke tester for each engine. Immutable namespace views share those collaborators and qualify caller-supplied execution, inspection, and diagnostic selections without rewriting captured references. Built-in engines provide the diagnostic HTTP collaborator; injected-client engines do not. It delegates identity listing directly to the captured configuration inventory rather than the runner. | [Engine assembly](../../internal/engine/engine.go), [internal sources](sources.md#typed-configuration-loading), [internal runner](runner.md) |
+| `internal/generation` | Coordinates frozen built-in HTTP attempts and one-shot injected calls through active backend permits, including bounded status retries, cancellable backoff, ordinary attempt observations, and invocation-local evidence for diagnostics. | [Internal generation coordination](generation.md) |
 | `internal/defaults` | Defines application-neutral framework constants and constructs the default execution target. It contains no CLI, server, or inbound HTTP limits. | [Framework defaults](../../internal/defaults/defaults.go) |
 | `internal/filecatalog` | Provides deterministic YAML discovery and path helpers for operating-system filesystems and `fs.FS` sources. | [File catalog](../../internal/filecatalog/catalog.go) |
 | `internal/jsonvalue` | Validates and deeply copies bounded JSON-compatible extra-parameter and prepared-schema trees while preserving supported concrete value types and rejecting cycles or excessive depth and work. | [JSON values](../../internal/jsonvalue/jsonvalue.go) |
 | `internal/promptdef` | Provides a narrow captured-prompt lookup contract, not-found identity, and execution-ready definition hash. | [Prompt lookup](../../internal/promptdef/repository.go), [framework formats](../formats.md) |
 | `internal/profile` | Provides a narrow captured-profile lookup contract and not-found identity. | [Profile lookup](../../internal/profile/repository.go), [framework formats](../formats.md) |
-| `internal/prompt` | Renders prompt messages from Go templates with artifact, variable, session, and cache-control data. | [Go-template renderer](../../internal/prompt/go_renderer.go) |
+| `internal/prompt` | Renders prompt messages from Go templates with artifact, variable, session, and cache-control data, and conservatively enumerates dependencies from captured template syntax. | [Go-template renderer](../../internal/prompt/go_renderer.go), [requirement discovery](../../internal/prompt/requirements.go) |
 | `internal/artifact` | Resolves ordinary inline and unrestricted caller-selected file references into copied artifacts with metadata and hashes. | [Internal sources and validation](sources.md) |
 | `internal/validate` | Validates basic, JSON, and JSON Schema output using operating-system filesystem or `fs.FS` schema sources and creates operation-local validation plans with canonical contained schema resources. | [Framework formats](../formats.md#schemas), [internal sources and validation](sources.md) |
-| `internal/llm` | Defines the internal generation boundary and implements outbound OpenAI-compatible chat requests from resolved execution targets, including bounded structured non-success response decoding, successful-response decoding, authentication, deadline handling, and ownership of the OpenAI-compatible reserved request-field policy. | [Internal model client](llm.md) |
-| `internal/observation` | Owns invocation-local run IDs, presence-aware usage and phase accounting, and synchronous metadata event delivery for ordinary and claimed prepared runs and generation attempts. | [Internal execution observation](observation.md) |
-| `internal/usecase` | Selects captured prompts and profiles, applies request overrides and completion checks, and coordinates ordinary and single-claim prepared execution across rendering, artifact loading, operation-local validation plans, generation, capacity, and bounded repair. | [Internal runner](runner.md), [prepared-execution implementation](../../internal/usecase/prepared_execution.go) |
+| `internal/llm` | Defines the internal generation boundary and implements outbound OpenAI-compatible chat requests from resolved execution targets, including bounded response decoding, authentication, deadline handling, per-invocation HTTP evidence and built-in diagnostic probes, and ownership of the OpenAI-compatible reserved request-field policy. | [Internal model client](llm.md) |
+| `internal/observation` | Owns invocation-local run IDs, presence-aware usage and phase accounting, and synchronous metadata event delivery for ordinary and claimed prepared runs and generation attempts; smoke diagnostics keep their private evidence outside ordinary observer events. | [Internal execution observation](observation.md) |
+| `internal/usecase` | Selects captured prompts and profiles, enumerates requirements from captured prompt syntax, applies request overrides and completion checks, coordinates ordinary and single-claim prepared execution across rendering, artifact loading, operation-local validation plans, generation, capacity, and bounded repair, and runs explicit smoke diagnostics with private cases, shared generation/capacity, and optional built-in HTTP probes. | [Internal runner](runner.md), [requirement inspection](../../internal/usecase/requirements_inspection.go), [prepared-execution implementation](../../internal/usecase/prepared_execution.go) |
 
 The internal engine assembles these internal components without exposing their
 representations. Consumers depend only on the root facade.

docs/internal/runner.md

@@ -32,16 +32,36 @@ The runner has no durable run or session store.
 
 ## Shared Prompt Selection
 
-The runner uses one prompt-selection and hashing boundary for ordinary
-preparation and exact prompt inspection. Preparation retains its early
-request-ID check before direct-session normalization; both operations select
-one captured definition and its construction-time hash. Referenced message
-content and static template syntax were captured when the engine was built.
+The internal engine applies each namespace view to slashless caller selections
+before they reach the runner. The runner therefore selects captured prompts and
+profiles by the resulting exact runtime IDs. Already-qualified selections pass
+through, while configured defaults and stored references are used as authored
+and are not requalified. Prompt version labels are returned as optional
+descriptive metadata; they are not prompt selectors.
 
-Inspection stops after that structural lookup. It does not render templates or
-touch profile, artifact, schema, renderer, validator, admission, or model
-collaborators. The root [`Engine.InspectPrompt`](../../engine.go) GoDoc owns
-the public operation's exact contract.
+Ordinary preparation selects the full prompt definition and construction-time
+hash. It retains its early request-ID check before direct-session
+normalization. Referenced message content and static template syntax were
+captured when the engine was built.
+
+`InspectPrompt` selects captured metadata through an optional repository
+capability, falling back to the full definition and existing hash resolution
+for internal repositories without it. It returns owned metadata without
+rendering templates or touching profile, artifact, schema, renderer, validator,
+admission, or model collaborators. The root
+[`Engine.InspectPrompt`](../../engine.go) GoDoc owns the public operation's
+exact contract.
+
+`InspectRequirements` uses the same metadata selection to resolve the
+request-profile/default identity, then obtains the captured requirement
+snapshot by the selected prompt ID. The analyzer receives only
+those identity fields rather than an execution definition. It analyzes the
+snapshot with the supplied caller variables and normalized direct-session
+bypass; it does not resolve target readiness or enter the preparation
+pipeline. Missing snapshot capability is a prompt-load failure rather than a
+source fallback. The root
+[`Engine.InspectRequirements`](../../requirements.go) GoDoc owns the public
+operation's exact contract.
 
 ## Shared Profile Selection
 
@@ -57,6 +77,37 @@ artifact, schema, rendering, admission, or model-client work. The root
 [`Engine.InspectProfile`](../../engine.go) GoDoc owns the public operation's
 exact contract.
 
+## Smoke-Test Diagnostics
+
+The separate `SmokeTester` in `internal/usecase` selects from the same captured
+configuration snapshot and backend/profile collaborators as the runner. The
+internal engine applies namespace-view qualification to slashless caller IDs
+before diagnostic selection; captured defaults and references remain exact.
+Explicit profile selection takes precedence over prompt-default selection and a
+backend diagnostic default; HTTP-only selection does not resolve a default
+inference profile. Exact public selection rules belong to the root
+[`Engine.SmokeTest` GoDoc](../../smoke_diagnostics.go).
+
+Diagnostics do not call `Run`, `Prepare`, or the prompt preparation pipeline.
+They do not render application messages, load application artifacts, use
+application schemas, or inspect session templates. Private text and structured
+cases and the structured case's schema remain internal to the diagnostic
+operation; they are not entries in prompt/profile listings or inspection.
+`InspectConfiguration` remains a separate, explicit operator-oriented view of
+effective settings and source history. A diagnostic report may include selected
+effective settings and identifiers, so consumers still apply their disclosure
+policy.
+
+The engine assembles the smoke tester with the runner's generation coordinator
+and capacity manager. Inference holds the ordinary logical admission lease and
+uses the same active permits, retries, timeout, and request evidence path as
+generation. Reachability and authentication probes bypass generation capacity
+and do not require a model. An engine with an injected `LLMClient` can run
+inference diagnostics but has no built-in HTTP probe collaborator; HTTP-only
+diagnostics report that limitation instead of falling back to another client.
+The public GoDoc owns the caller-visible timeout, cancellation, report, and
+transport semantics.
+
 ## Shared Preparation Pipeline
 
 `Prepare` and `Run` share one private preparation pipeline split at the point
@@ -92,8 +143,17 @@ one execution-precedence and error-ordering implementation while allowing a
 full backend pool to reject work before expensive schema, artifact, and
 rendering operations. `Prepare` discards the plan after returning its public
 metadata. `Run` retains the plan through initial and repaired-output validation
-and discards it when the operation ends. Prepared execution stores the same
-kind of plan only in its private payload.
+and discards it when the operation ends. Prepared execution transfers the
+completed preparation's owned message, input-hash, and copied-schema values
+into its private payload, while deep-copying mutable provider extras and
+creating an independent details snapshot. Claim completion or discard clears
+the execution payload without removing the details snapshot.
+
+The root facade's `Engine.ValidateRequest` uses the same complete preparation
+path as `Prepare` and discards the resulting internal prepared value without
+converting it into a public snapshot. It does not add a runner operation or
+validator component; request conversion and public error mapping remain at the
+facade boundary.
 
 Pointer-based numeric overrides preserve an explicit zero. Invalid negative or
 out-of-range values fail as invalid requests. Endpoint overrides do not change
@@ -234,4 +294,8 @@ Changes to orchestration should continue to use the existing package
 interfaces, keep request state local to an invocation, and preserve the shared
 resolution and completion pipeline. Source, renderer, validator, or
 model-client contract changes belong first in their owning package and
-document.
+document. The
+[smoke selection tests](../../internal/usecase/smoke_selection_test.go),
+[diagnostic orchestration tests](../../internal/usecase/smoke_tester_test.go),
+and [private inference-case tests](../../internal/usecase/smoke_inference_test.go)
+own diagnostic selection, report assembly, and inference findings.

docs/internal/sources.md

@@ -14,61 +14,149 @@ source semantics. Internal packages are not consumer APIs.
 effective configuration to execution-owned definitions. It performs one
 layered load, captures effective presence (including explicit null), records
 normalization and defaults through resolution, and validates all effective
-backend, profile, and prompt values. Replaced lower-layer domain values are
-not separately validated. It builds an immutable backend index and
-presence-aware profile targets, applying final backend defaults only after
-profile inheritance. It retains ConfigKit's result privately for explicit
-inspection, not for per-run resolution. The runtime/domain packages do not
-depend on ConfigKit.
+root and collection backend, profile, and prompt values. Replaced lower-layer
+domain values are not separately validated. It indexes root resources under
+their unqualified IDs and collection resources under their full
+`namespace/local-key` IDs while retaining ConfigKit's effective tree in its
+authored shape. It builds an immutable backend index and presence-aware profile
+targets, applying final backend defaults only after profile inheritance. Runtime
+lookups use those final indexes and exact stored references; they do not rewrite
+or resolve resources from ConfigKit source history. The runtime/domain packages
+do not depend on ConfigKit.
+
+ConfigKit owns source headers, imports, composition, and source evidence.
+Promptkit does not preparse contributions: it validates the final effective
+values once, captures the indexed identities and their original resource
+contexts, and retains ConfigKit's result for explicit operator inspection.
+Accepted non-main source headers are consumed during composition; the main
+source declaration remains available in that inspection view. Prompt and
+collection release labels are descriptive metadata, not selection inputs. The
+[format reference](../formats.md#source-headers-collections-and-resource-ids)
+owns the exact source-header and collection contracts.
+
+The `ConfigurationInspection.Diff` facade method compares two retained results
+through a private wrapper and a narrow `internal/configuration.Diff` bridge.
+The wrapper keeps `Result[document]` inside the adapter; the bridge delegates
+once to ConfigKit v0.8.0 and returns its public difference records. Comparison
+uses only frozen effective values and does not reopen sources, resolve runtime
+credentials, or enter the execution path. ConfigKit applies sensitivity from
+both results; reports may still contain ordinary application data. See the
+[consumer comparison guide](../consumers/pkg-promptkit.md#inspect-the-captured-configuration)
+and ConfigKit's [v0.8.0 comparison contract](https://gitea.maximumdirect.net/eric/ConfigKit/src/tag/v0.8.0/docs/config.md#effective-configuration-diffs).
+
+After resource materialization and effective-profile snapshot construction, the
+adapter captures lexically ordered identity inventories for backends, profiles,
+and prompts, per-kind resource namespace sets, and metadata for effective
+collection declarations. Listing methods return caller-owned copies from those
+captured values without consulting ConfigKit or copying resource definitions.
 
 The root `DirectoryInputs` and `FilesystemInputs` helpers discover sorted YAML
 files under an explicit root, provide resource context, and leave imports
 disabled. Each returned slice belongs to one strict-composition group; file
-order does not confer priority. The engine prepends selected catalog and
-Promptkit-owned definitions, then caller underlays and optional main. The
+order does not confer priority. Caller underlays are composed in their given
+order, followed by the optional main input. The
 [configuration tests](../../internal/configuration/load_test.go) exercise the
 real loader and final-value handoff.
 
+The public `CollectionInput` helper mounts one caller-selected source at
+`collections/<namespace>` and enables ConfigKit imports for that input. The
+helper does not read the source; ConfigKit retains responsibility for loading,
+composition, imports, and source-local resource context. Imported or inherited
+`content_file` values continue resolving relative to the source that contributed
+the effective field, not to a flattened runtime identity. Explicit
+`InspectConfiguration` views expose the retained effective configuration and
+provenance for operator review; runtime selection and inventories do not derive
+from source history.
+
 ## Prompt Definitions
 
-The configuration adapter indexes each prompt by exact ID and version,
+The configuration adapter indexes each prompt by exact ID,
 materializes file-backed message content using the exact effective field's
 origin and resource context, and checks static message/session template syntax
 at construction. It stores captured content, compiled templates, declared
-input metadata, and a definition hash. It closes content-file handles before
+input metadata, and a definition hash. Alongside the unchanged hashed
+definition, it retains content-type and description presence for each declared
+input and provides an internal requirement snapshot with those declarations
+and the captured parses. Metadata values come from the final normalized
+declaration; absent and null fields remain distinguishable from explicit
+strings, including empty strings. It closes content-file handles before
 returning and retains no source capability for public inspection.
 
-Role and cache-control normalization is applied to execution-owned message
-copies. The retained ConfigKit configuration keeps effective input message
-metadata and its resource origins: recording a sequence-wide normalization in
-ConfigKit v0.5.0 would replace origins of unchanged content-file fields.
+Prompt materialization shares a lazy metadata snapshot across root and collection
+resources during construction, avoiding a full metadata copy per collection.
 
-The runner selects from this index for preparation and `InspectPrompt`.
-Neither path rescans configuration or reopens message files. `InspectPrompt`
+Role and cache-control normalization is applied to execution-owned message
+copies. ConfigKit v0.8.0 retains effective input message metadata and its
+resource origins; recording a sequence-wide normalization in the retained
+configuration would replace origins of unchanged content-file fields.
+
+The runner selects full definitions from this index for preparation and uses
+captured prompt metadata for `InspectPrompt` and `InspectRequirements`; the
+internal requirement snapshot lookup uses the selected prompt ID alone.
+These paths do not rescan configuration or reopen message files. `InspectPrompt`
 returns declared metadata without rendering or resolving profile, input, or
-schema resources. Runtime rendering still checks request variables and input
-helpers. The [prompt adapter tests](../../internal/configuration/prompts_test.go)
+schema resources, and its public shape and prompt hashes do not include the
+captured presence state. Runtime rendering still checks request variables and
+input helpers. The [prompt adapter tests](../../internal/configuration/prompts_test.go)
 cover resource origins, context containment, capture, and selection.
 
-## Profiles And Built-Ins
+The configuration adapter shares ID-only selection across its internal prompt
+lookups. The execution snapshot lookup returns an owned prompt
+definition and cached hash; metadata inspection returns owned input metadata
+without copying execution templates. Profile selection likewise has an
+identity-only lookup for consumers that do not need the execution target,
+while the full profile lookup continues to return an owned target and deep copy
+of provider extras. These lookups use captured indexes and do not query
+ConfigKit again.
 
-`internal/catalog` selects the released keyed OpenRouter and Rakestrawhome
-assets as one ConfigKit underlay and PromptKit-owned profiles as the next.
-It discovers YAML inputs and supplies passive filesystem context without
-parsing or pre-validating catalog definitions. The configuration loader
-validates only the final effective backend and profile values, including
-consumer overlays of maintained bases or backends. There is no catalog-only
-preflight, reserved source namespace, or replay of backend registration.
+The `internal/prompt` requirement walker uses the captured parse trees and
+declaration metadata without executing templates or reading artifacts. It
+collects literal `input` names, direct root caller keys, and literal-key
+`index` lookups. For `if` and `with`, it classifies branches when their
+conditions are simple supported values: direct values, literals, negation, or
+two-string equality/inequality. It uses Go template truthiness, so a supplied
+nonempty string such as `false` is true. Missing decision values and
+content-dependent conditions leave dependency-bearing branches conditional
+and report incomplete discovery; unresolved conditions with no branch
+dependencies do not by themselves make discovery incomplete. Recognizable
+references on known skipped paths remain optional inventory entries with an
+inactive-use explanation, unless another applicable use establishes a
+stronger classification. Skipped expressions are scanned only for
+syntactically recognizable names and are not evaluated. A direct caller value
+or literal-key lookup can also supply an input name, including through simple
+parentheses or a direct pipeline to `input`; names are used exactly as
+supplied. Unresolved names and unsupported dependency-bearing expressions
+produce structured limitations while retaining recognizable references.
+Where an unresolved name or scope could affect existing optional entries, those
+entries are reported as conditional rather than inactive-only or definitively
+optional. Direct root-map `with` forms retain caller-map identity. Known scalar
+values remain separate from unknown scopes; accesses through untracked local
+maps report incomplete discovery rather than silently losing caller keys.
+Unsupported name expressions reuse value analysis's conservative syntax scan
+instead of recursively rescanning the same subtree.
+Invoked named templates are scanned conservatively, and
+dependency-bearing range scopes make discovery incomplete. Uncalled definitions
+and bypassed session templates are not traversed. This internal walker does not
+change rendering behavior.
 
-ConfigKit resolves profile inheritance before the handoff. The configuration
-adapter validates effective references and field values, then builds target
+## Profiles
+
+ConfigKit resolves profile inheritance before the handoff. Within a collection,
+`extends` names a sibling local key; it is not a cross-collection reference.
+The configuration adapter validates final effective resource references and
+field values, then builds target
 snapshots with backend defaults and presence/suppression state. A profile can
 remain partial until runtime overrides complete it. `InspectProfile` selects
 that captured target without prompt, artifact, schema, credential lookup, or
 provider work. Preparation applies runtime overrides and then checks target
-completeness. The [target tests](../../internal/configuration/targets_test.go)
-cover effective target interpretation, while the [catalog tests](../../internal/catalog/catalog_test.go)
-cover selected released assets.
+completeness. Identity-only profile selection can identify a partial captured
+profile without copying its target or requiring readiness. The
+[target tests](../../internal/configuration/targets_test.go) cover effective
+target interpretation.
+
+The internal engine delegates listing through a narrow identity-inventory
+interface directly to the configuration snapshot. The execution runner has no
+listing responsibility.
 
 ## Ordinary Artifacts
 
@@ -79,10 +167,15 @@ and after opening the file. It copies content into an artifact, records
 metadata and an opaque content-equality value, and applies a content-type
 fallback.
 
-Regular files are read synchronously in bounded chunks. Cancellation is
-checked before opening, before and after every read, and before publishing the
-artifact, so a canceled read never publishes partial content. The ordinary
-reader does not detach file reads into background goroutines.
+Regular files are read synchronously in bounded chunks. The opened file's size
+is only an initial-capacity hint, capped at 1 MiB; reads continue to EOF, and
+the returned body determines artifact size and hash. If an overreported hint
+leaves unused capacity greater than the actual body length, the completed body
+is copied to release the excess backing storage, including when the body is
+empty. Cancellation is checked before opening, before and after every read,
+and before publishing the artifact, so a
+canceled read never publishes partial content. The ordinary reader does not
+detach file reads into background goroutines.
 
 This ordinary reader does not implement an inbound HTTP security boundary. In
 particular, it does not constrain files to an application root or impose an
@@ -106,7 +199,9 @@ between artifact conversion chunks, around each message, and before publishing
 the complete prompt. It cannot interrupt template work already in progress and
 never publishes a partial prompt after observing cancellation. It validates and
 canonicalizes message roles before carrying roles, session IDs, and cache
-control into the rendered prompt. The
+control into the rendered prompt. Message and session templates execute into
+per-call string builders, so their rendered strings do not require a final
+buffer-to-string copy. The
 [renderer tests](../../internal/prompt/renderer_test.go) own rendering behavior.
 
 ## Schemas And Output Validation
@@ -114,7 +209,8 @@ control into the rendered prompt. The
 `internal/validate` provides validators backed by an operating-system
 filesystem or an `fs.FS`. Invalid generated content is returned as a validation
 result; inability to load, register, or compile a schema is an operational
-error.
+error. Basic validation checks body emptiness on the byte slice directly
+instead of first making a response-sized string copy.
 
 Every preparation operation creates one operation-local validation plan. None,
 basic, and JSON modes retain the effective output contract without source

docs/oss/attribution.md

@@ -6,59 +6,37 @@ Material: policy documents under `docs/policy/` and the Policy Reading Guide in
 `docs/development.md`, adapted for this repository; root `AGENTS.md`, copied
 without modification from upstream `agents/AGENTS.md`.
 
+The release policy uses upstream commit
+`e833faddf120c789a9b45348edaf75720de16348`; the remaining material uses
+`d84a38ebab26f048cafbe59a2246700c35d29843`.
+
 Copyright (C) 2026 Eric Rakestraw
 
 SPDX-License-Identifier: CC-BY-SA-4.0
 
 License and notices: [CC BY-SA 4.0](licenses/CC-BY-SA-4.0.txt) |
 [COPYRIGHT](https://gitea.maximumdirect.net/eric/policy/src/commit/d84a38ebab26f048cafbe59a2246700c35d29843/COPYRIGHT) |
-[LICENSE](https://gitea.maximumdirect.net/eric/policy/src/commit/d84a38ebab26f048cafbe59a2246700c35d29843/LICENSE).
+[LICENSE](https://gitea.maximumdirect.net/eric/policy/src/commit/d84a38ebab26f048cafbe59a2246700c35d29843/LICENSE) |
+[COPYRIGHT](https://gitea.maximumdirect.net/eric/policy/src/commit/e833faddf120c789a9b45348edaf75720de16348/COPYRIGHT) |
+[LICENSE](https://gitea.maximumdirect.net/eric/policy/src/commit/e833faddf120c789a9b45348edaf75720de16348/LICENSE).
 
 [Source](https://gitea.maximumdirect.net/eric/policy/src/commit/d84a38ebab26f048cafbe59a2246700c35d29843).
 
+[Source](https://gitea.maximumdirect.net/eric/policy/src/commit/e833faddf120c789a9b45348edaf75720de16348).
+
 ## ConfigKit
 
-Selected module: `gitea.maximumdirect.net/eric/ConfigKit` at `v0.5.0`.
+Selected module: `gitea.maximumdirect.net/eric/ConfigKit` at `v0.8.0`.
 
 Copyright (C) 2026 Eric Rakestraw
 
 SPDX-License-Identifier: LGPL-3.0-or-later
 
 License and notices: [LGPL 3.0](../../LICENSE) |
-[COPYRIGHT](https://gitea.maximumdirect.net/eric/ConfigKit/src/commit/dc09959cca4e105f49ec316c6d4ba585bd2340bd/COPYRIGHT) |
-[LICENSE](https://gitea.maximumdirect.net/eric/ConfigKit/src/commit/dc09959cca4e105f49ec316c6d4ba585bd2340bd/LICENSE).
+[COPYRIGHT](https://gitea.maximumdirect.net/eric/ConfigKit/src/commit/137769f3f18a370c68444242fb5d88e620e307e5/COPYRIGHT) |
+[LICENSE](https://gitea.maximumdirect.net/eric/ConfigKit/src/commit/137769f3f18a370c68444242fb5d88e620e307e5/LICENSE).
 
-[Source](https://gitea.maximumdirect.net/eric/ConfigKit/src/commit/dc09959cca4e105f49ec316c6d4ba585bd2340bd).
-
-## Promptkit OpenRouter Catalog v3
-
-Selected module: `gitea.maximumdirect.net/eric/promptkit-backend-openrouter/v3`
-at `v3.20260930.0`.
-
-Copyright (C) 2026 Eric Rakestraw
-
-SPDX-License-Identifier: MIT
-
-License and notices: [MIT](licenses/MIT.txt) |
-[COPYRIGHT](https://gitea.maximumdirect.net/eric/promptkit-backend-openrouter/src/commit/f17d208cb7ad1fb043cda2266cd3011d11b40aa0/COPYRIGHT) |
-[LICENSE](https://gitea.maximumdirect.net/eric/promptkit-backend-openrouter/src/commit/f17d208cb7ad1fb043cda2266cd3011d11b40aa0/LICENSE).
-
-[Source](https://gitea.maximumdirect.net/eric/promptkit-backend-openrouter/src/commit/f17d208cb7ad1fb043cda2266cd3011d11b40aa0).
-
-## Promptkit Rakestrawhome Catalog v3
-
-Selected module: `gitea.maximumdirect.net/eric/promptkit-backend-rakestrawhome/v3`
-at `v3.20260930.0`.
-
-Copyright (C) 2026 Eric Rakestraw
-
-SPDX-License-Identifier: MIT
-
-License and notices: [MIT](licenses/MIT.txt) |
-[COPYRIGHT](https://gitea.maximumdirect.net/eric/promptkit-backend-rakestrawhome/src/commit/993443d88c451901f4c917fa00c204fd3b54d28d/COPYRIGHT) |
-[LICENSE](https://gitea.maximumdirect.net/eric/promptkit-backend-rakestrawhome/src/commit/993443d88c451901f4c917fa00c204fd3b54d28d/LICENSE).
-
-[Source](https://gitea.maximumdirect.net/eric/promptkit-backend-rakestrawhome/src/commit/993443d88c451901f4c917fa00c204fd3b54d28d).
+[Source](https://gitea.maximumdirect.net/eric/ConfigKit/src/commit/137769f3f18a370c68444242fb5d88e620e307e5).
 
 ## jsonschema
 

docs/policy/architecture.md

@@ -51,8 +51,8 @@ The [internal component overview](../internal/overview.md) owns the inventory
 of implemented packages and their concrete responsibilities. This policy owns
 the boundaries and dependency rules those components must preserve.
 
-The internal engine composes selected catalog and caller ConfigKit inputs once,
-then assembles the captured definitions, capacity manager, renderer, validator,
+The internal engine composes caller-selected ConfigKit inputs once, then
+assembles the captured definitions, capacity manager, renderer, validator,
 outbound client, and use-case runner. The configuration adapter interprets and
 validates only the final effective values, including presence, null, and
 resource context. It retains source history for explicit operator inspection,
@@ -97,7 +97,8 @@ on consumers or on Scriptorium.
 `internal/domain` owns source-neutral invariants for values shared across
 multiple input and execution boundaries, including execution-setting bounds,
 OpenAI-compatible base endpoints, session identifiers, and output-contract
-legality. Callers retain source parsing, required-field rules, other
+legality, plus shared resource-identity syntax and qualification. Callers retain
+source parsing, required-field rules, other
 source-specific normalization, defaulting, error classification, and policy
 specific to their own boundary.
 

docs/policy/documentation.md

@@ -88,7 +88,7 @@ secret values.
 | Release-note history | `docs/releases/` | One checked-in summary per source release under the procedure; the note at its immutable tag is the release record. | Current commands, behavior, contracts, and compatibility definitions. |
 | Complete copyable artifacts | `examples/` | Maintained configuration, inputs, and other copyable or runnable files. | Field-by-field reference, command reference, prose explanation. |
 | Exact exported Go API | Go declarations and GoDoc, as APIs are implemented | Exported names, signatures, types, values, errors, and exact behavioral contracts. | Task-oriented consumer walkthroughs, implementation details, and future API proposals. |
-| Framework file formats | `docs/formats.md` | Prompt-definition and profile YAML fields, schema references, defaults, validation modes, built-in profiles, credentials, and file-to-request precedence. | Exported Go declarations, outbound wire behavior, internal parsing mechanics, and application configuration. |
+| Framework file formats | `docs/formats.md` | Prompt-definition and profile YAML fields, schema references, defaults, validation modes, credentials, and file-to-request precedence. | Exported Go declarations, outbound wire behavior, internal parsing mechanics, and application configuration. |
 
 Create supporting documents for existing interfaces and responsibilities when
 substantive content is available.

docs/policy/release.md

@@ -1,10 +1,10 @@
 # Release Policy
 
-**Base Policy Version:** 1.4
+**Base Policy Version:** 1.6
 
-**Last Updated**: 2026-09-27
+**Last Updated**: 2026-10-08
 
-**Upstream Source:** [release.md](https://gitea.maximumdirect.net/eric/policy/src/commit/d84a38ebab26f048cafbe59a2246700c35d29843/docs/policy/release.md)
+**Upstream Source:** [release.md](https://gitea.maximumdirect.net/eric/policy/src/commit/e833faddf120c789a9b45348edaf75720de16348/docs/policy/release.md)
 
 ## Purpose
 
@@ -12,6 +12,9 @@ This policy defines a proportionate workflow for validating and publishing an
 intended source revision under a fresh version. Releases should require little
 routine intervention, avoid repeated work, and preserve published contents.
 
+Adopt stronger verification or reproducibility requirements through an explicit
+project-specific decision justified by the intended audience and support needs.
+
 The repository-specific commands belong in `docs/release.md`. Historical release
 summaries belong in `docs/releases/`. The procedure must agree with the adopted
 policy and link to it rather than introduce additional release requirements.
@@ -59,7 +62,8 @@ requires a deliberate update to the policy and procedure where needed.
 For releases at or after `v1.0.0`:
 
 - a major release may make intentional incompatible changes;
-- a minor release may add backward-compatible behavior; and
+- a minor release may add backward-compatible behavior or raise the Go consumer
+  minimum as described below; and
 - a patch release may make backward-compatible fixes.
 
 Before `v1.0.0`, a minor release may change a documented public, operational,
@@ -71,14 +75,44 @@ Additional compatibility promises and deliberate exceptions belong in the
 adopted policy or canonical contract documentation. Release notes explain
 changes; they do not redefine current compatibility contracts.
 
-## Release Documentation
+## Consumer Minimum And Release Toolchain
+
+Distinguish the minimum toolchain supported for consumers from the toolchain
+maintainers use to build and validate a release. Record the consumer minimum in
+the language's standard metadata and explain its support meaning in canonical
+documentation. Define the selected release toolchain and its setup commands in
+`docs/release.md`. Toolchain selection and upgrade cadence are repository-specific
+choices.
+
+For Go repositories, normally declare the initial stable release of the selected
+series as the consumer minimum, such as `go 1.26.0`. Use a higher patch minimum
+when a dependency or an identified correctness fix requires it, and document
+the reason.
+
+For release-policy purposes, successful build and release validation on the
+selected Go patch release are sufficient to presume support across that Go
+series, subject to the declared consumer minimum and concrete evidence of
+incompatibility. Investigate specific compatibility concerns as they arise.
+
+Use the selected release toolchain for candidate validation and release builds,
+including CI jobs performing those tasks. A newer validation patch version alone
+leaves the consumer minimum unchanged.
+
+A minor release may raise the Go consumer minimum, including from one Go series
+to the next, both before and after `v1.0.0`. This is an explicit exception to the
+backward-compatibility requirement for minor releases. Patch releases preserve
+the consumer minimum. Explain an increase's impact and required consumer action
+in the release note. Other incompatible changes remain subject to the versioning
+rules above.
+
+## Release Documentation And Preparation
 
 Every new release must include `docs/releases/<version>.md` in the tagged
 source tree. Use the complete version tag as the filename and begin with a
 title containing the product name and that exact version.
 
 Include a short summary and any relevant compatibility impact or upgrade
-instructions. Use the Promptkit section structure below and keep the note
+instructions. Choose sections suited to the release and keep the note
 proportionate to the change.
 
 Keep exact current contracts in their canonical documents and update affected
@@ -186,7 +220,8 @@ release without replacing its contents or reusing its version.
 Maintain `docs/release.md` as a short, executable maintainer runbook. It must
 identify:
 
-1. prerequisites, primary branch, and authoritative remote;
+1. prerequisites, selected release toolchain, primary branch, and authoritative
+   remote;
 2. version and release-note preparation;
 3. one publication command with its selected local checks and automated guards;
 4. declared deliverables, required build targets, and automation responsibilities;
@@ -210,43 +245,36 @@ annotated stable SemVer tags. It has no binaries, hosted download pages, or
 asynchronous deliverables. The source commit is pushed through main before the
 tag. The [release procedure](../release.md) owns commands and recovery.
 
-The existing publication script requires Summary, Compatibility, Upgrade, and
-Changes headings beneath a title of `# Promptkit vMAJOR.MINOR.PATCH`. State
-“No action required” or “None” where appropriate. This retained local structure
-matches the automated release-note guard; changing it is separate work.
+Release preparation uses the latest Go installation available in the development
+environment to build the maintainer release executable and validate the
+candidate, including the consumer examples. Keep that same local toolchain
+active throughout those operations.
 
-The [publication script](../../scripts/release.sh) runs the
-[local checks](../../scripts/release-check.sh) once for the final committed
-candidate: race-enabled tests, vet, three offline consumer examples, tracked
-Go formatting, Markdown links, module/workspace hygiene, whitespace, and a
-credential-pattern scan. These protect concurrency, assembled library use,
-source distribution, and documentation integrity. A separate ordinary test run
-or standalone build is not an additional release gate. Candidate, tag, and
-synchronized-main checks remain automated. No CI or module-availability wait
-is required. Licensing footer URLs are preparation work, not a network gate.
+For a minor release, advance Promptkit's consumer minimum to the initial stable
+release of that Go series, retaining a higher patch minimum when required by a
+dependency or an identified correctness fix. Patch releases preserve the
+existing consumer minimum. Commit any module update before validating the final
+candidate. The [release procedure](../release.md#prepare-the-candidate) owns
+setup commands, and the consumer guide explains
+[Go compatibility](../consumers/pkg-promptkit.md#go-compatibility).
 
-## Catalog Profile Compatibility
+Use a title containing `Promptkit` and the exact version, followed by a short
+summary and any relevant compatibility impact or upgrade instructions. The
+note is committed with the candidate and supplies the annotated tag message.
+No fixed set of section headings is required.
 
-External catalog profile data may be added, removed, renamed, or modified
-without deprecation or advance notice. This exception is limited to profile
-data imported from the maintained catalog modules. It does not weaken ordinary
-compatibility for Promptkit's public Go API, configuration and format semantics,
-runtime behavior, catalog-module APIs, manifest schema, backend definitions, or
-consumer-owned definitions.
-
-Within the catalog versions selected and tested by a Promptkit release, and
-unless a consumer overrides the name or its base, Promptkit keeps the literal
-profile IDs `promptkit-openrouter-standard` and
-`promptkit-openrouter-auto` available. The names do not promise a permanent
-model, backend, routing behavior, settings, cost, output, or upstream
-availability. The [framework format reference](../formats.md#built-in-profile-catalog)
-owns their current definitions.
-
-`v0.10.0` is the initial minor release for this compatibility transition.
-Afterward, catalog-only updates and adjustments to the current selections may
-ship in a patch release when all other compatibility obligations remain intact.
-External profile removals can require consumer action; they are not automatic
-migrations.
-
-Catalog adoption and release validation remain local and offline. They do not
-probe provider endpoints, request model lists, or make inference calls.
+The [publication command](../../scripts/release.sh) delegates to the released
+ReleaseKit tool selected in `go.mod`. The committed
+[profile](../../releasekit.json) selects the race-enabled Go suite, full vet,
+committed Go formatting, local Markdown links, workspace and filesystem
+replacement inspection, and the offline semantic checks for the three
+maintained consumer examples. These are the selected checks for the final
+candidate; a separate ordinary test run or standalone build is not an
+additional release gate. The upstream tool owns candidate, remote, and tag
+publication checks. It returns native status 0 for confirmed publication, 1
+for a known validation or publication failure, 2 for invalid input or profile,
+and 3 when the push outcome is unknown. For status 3, resolve the exact
+captured publication endpoint before retrying; the repository-specific
+[procedure](../release.md#failure-recovery) links to the upstream recovery
+instructions. Do not wait for CI or Go module availability. Licensing footer
+URLs are preparation work, not a network gate.

docs/policy/testing.md

@@ -58,17 +58,24 @@ and repository hygiene.
 Introducing hosted CI later would supplement, not silently redefine, this
 documented validation model.
 
-Full release-candidate validation includes race-enabled package tests, explicit
-static analysis, and execution with automated semantic checks of the three maintained
-offline consumer examples. The test run builds the packages; the examples
-also exercise ordinary compilation. Separate ordinary tests and a standalone
-build are not additional release gates. Ordinary tests remain useful during
-development. The preparation example protects assembled preparation and
+The selected ReleaseKit profile runs the race-enabled package suite and full
+vet, checks committed Go formatting, local Markdown links, and module
+distribution hygiene, and executes semantic assertions for the three
+maintained offline consumer examples. ReleaseKit owns this shared validation
+machinery and publication workflow. The test run builds the packages; the
+examples also exercise ordinary compilation. Separate ordinary tests and a
+standalone build are not additional release gates. Ordinary tests remain useful
+during development. The preparation example protects assembled preparation and
 inspection behavior. The execution example separately protects assembled
 `Run`, injected-client, validation, usage, and result behavior. The observation
 example protects assembled built-in retries, structured proposal and assessment
 runs, and application-owned interpretation of metadata.
 
+The standalone `python3 scripts/test-release.py` command exercises Promptkit's
+ReleaseKit wiring against disposable local repositories. It is focused
+development validation when release tooling changes, not part of the default
+Go test suite or a recurring release check.
+
 Tests in the default suite must be deterministic, offline, and independent of
 real credentials. They must not invoke paid APIs, use live network
 dependencies, or depend on mutable external services. Tests that require live

docs/release.md

@@ -1,94 +1,130 @@
 # Release Procedure
 
-This runbook implements the [release policy](policy/release.md). A successful
-push of the selected annotated tag to origin completes the release. Never wait
-for CI to finish or succeed.
+This runbook implements the [release policy](policy/release.md). Promptkit
+publishes source-only Go module tags from `main` to `origin`. A successful push
+of the selected annotated tag, after its source commit is available on `main`,
+completes the release. Do not wait for CI or Go module availability.
 
 ## Prepare The Candidate
 
 Required tools are Git, Go with race-detector support, POSIX shell, and Python
-3. Publication requires push access to origin. Work from the repository root.
+3. Work from the repository root with push access to `origin`.
 
-Select an unused version and create `docs/releases/<version>.md` using the
-[required structure](policy/release.md#release-documentation). Describe
-compatibility impact and consumer actions and update affected canonical docs.
-For catalog updates, record selected catalog versions and any consumer action,
-linking to the catalog policy rather than repeating its contracts.
+Use the latest Go installation available locally for the release tool, the
+candidate validation, and the maintained examples. Make it the active `go`
+command and record its version:
 
-Follow the [OSS policy](policy/oss.md) when preparing licensing and attribution
-changes. Each new note must end with the following navigation, replacing
-`vMAJOR.MINOR.PATCH` with the selected release tag:
-
-```markdown
-[COPYRIGHT](https://gitea.maximumdirect.net/eric/promptkit/src/tag/vMAJOR.MINOR.PATCH/COPYRIGHT) | [LICENSE](https://gitea.maximumdirect.net/eric/promptkit/src/tag/vMAJOR.MINOR.PATCH/LICENSE) | [ATTRIBUTION](https://gitea.maximumdirect.net/eric/promptkit/src/tag/vMAJOR.MINOR.PATCH/docs/oss/attribution.md)
+```sh
+export GOTOOLCHAIN=local
+go version
 ```
 
-Check these file paths against the candidate; a future tag need not resolve
-remotely during preparation. The annotated tag derives from this same note,
-including its footer. Promptkit publishes no separate hosted release body or
-download page. If such a channel is deliberately introduced, reuse the note
-and preserve its footer. No extra network checks, artifacts, or approval gates
-are introduced, and published notes are not retrofitted.
+For a minor release, advance Promptkit's consumer minimum to the initial stable
+release of that Go series before committing the candidate:
 
-Retire completed roadmaps, preserving planned or deferred work and repairing
-links. This is housekeeping, not a separate approval gate. Review changes
-through the ordinary development workflow, commit them, and push main to
-origin. No repeated release-specific diff review is required.
+```sh
+release_go_version=$(go env GOVERSION)
+release_go_series=${release_go_version#go}
+release_go_series=${release_go_series%.*}
+go mod edit "-go=${release_go_series}.0"
+```
+
+For example, Go 1.26.8 normally results in `go 1.26.0`. Keep a higher patch
+minimum if a dependency or identified correctness fix requires it. For a patch
+release, leave the consumer minimum unchanged; using a newer validation
+toolchain does not itself raise that minimum. If the candidate needs a higher
+minimum, prepare a minor release instead. See the
+[consumer-minimum policy](policy/release.md#consumer-minimum-and-release-toolchain).
+
+Prepare module caches before validation; this may update `go.sum` and belongs
+before the candidate commit:
+
+```sh
+GOTOOLCHAIN=local go mod download
+```
+
+Choose an unused stable version and create `docs/releases/<version>.md` with a
+title containing `Promptkit` and that exact version, a short summary, and any
+relevant compatibility impact or upgrade instructions. No fixed section
+headings are required. Describe a raised Go minimum and its compatibility
+impact under the [versioning policy](policy/release.md#versioning-and-compatibility).
+End each new note with the licensing footer below, using the selected version:
+
+```markdown
+[COPYRIGHT](https://gitea.maximumdirect.net/eric/promptkit/src/tag/vX.Y.Z/COPYRIGHT) | [LICENSE](https://gitea.maximumdirect.net/eric/promptkit/src/tag/vX.Y.Z/LICENSE) | [ATTRIBUTION](https://gitea.maximumdirect.net/eric/promptkit/src/tag/vX.Y.Z/docs/oss/attribution.md)
+```
+
+Check the footer paths against the candidate; the future tag need not resolve
+remotely during preparation. Follow the [OSS policy](policy/oss.md) for these
+links. Promptkit publishes no binaries, hosted download page, or other
+asynchronous deliverables.
+
+Retire completed roadmaps while preserving deferred work and repairing incoming
+links. Review the intended changes through the ordinary development workflow,
+commit the candidate on `main`, and push `main` to `origin` before publication.
+Preparation may update module metadata; the release bootstrap and validation
+preserve the committed candidate.
 
 ## Validate And Publish
 
-Run the following with the chosen unused version (replace the placeholder):
+For an optional local diagnostic of a committed candidate, run:
+
+```sh
+./scripts/releasekit.sh check vMAJOR.MINOR.PATCH
+```
+
+This is not a required step before publication. The upstream
+[candidate-check contract](https://gitea.maximumdirect.net/eric/ReleaseKit/src/tag/v0.4.1/docs/consumers/check.md)
+describes its requirements.
+
+Run the single publication command with the chosen version:
 
 ```sh
 ./scripts/release.sh vMAJOR.MINOR.PATCH
 ```
 
-The [publication script](../scripts/release.sh) checks a clean, synchronized
-main candidate, the version and unused tag, and the release note's title and
-required headings. It runs the [local checks](../scripts/release-check.sh)
-once, rechecks candidate identity and publication state, generates the
-annotation from the committed note plus the validated commit, and pushes only
-the selected annotated tag.
+The familiar wrapper delegates to the native ReleaseKit executable selected in
+`go.mod`. The committed [profile](../releasekit.json) selects the race-enabled
+Go suite, full vet, committed Go formatting, local Markdown links, workspace
+and filesystem replacement inspection, and semantic checks for the three
+maintained offline consumer examples. ReleaseKit also verifies the committed
+candidate and publication state, then publishes only the selected tag. Its
+checks run once for this candidate; do not repeat them as a separate sign-off.
 
-There is no separate tag-message authoring, example-output inspection,
-metadata inspection, or human sign-off. Compatibility and release-note content
-remain ordinary editorial responsibilities. Development validation is useful
-but does not require a second full run before invoking the publication script.
-
-The script stops successfully after the tag push. CI completion, CI success,
-remote read-back, and Go module availability are not release completion gates.
-Do not wait or poll for them. Provider probes and inference calls are never
-part of release validation.
-
-## Catalog Profile Compatibility
-
-The [release policy](policy/release.md#catalog-profile-compatibility) owns the
-catalog compatibility boundary. This heading preserves older incoming links.
+The native command returns status 0 for confirmed publication, 1 for a known
+validation or publication failure, 2 for invalid input or profile, and 3 when
+the push outcome remains unknown. Successful publication needs no remote
+read-back, CI wait, or installation check. Provider probes and inference calls
+are not part of validation.
 
 ## Failure Recovery
 
-If local checks fail, fix the candidate, commit and push changes, then rerun
-the publication command. It never automatically removes a tag.
+For status 1, use the diagnostic to distinguish a validation failure from a
+known publication conflict. Correct and commit candidate defects, push `main`,
+and rerun publication with an unused version when appropriate. Status 2 means
+the invocation or profile must be corrected.
 
-If a push fails or its result is ambiguous, set `RELEASE_VERSION` to the
-attempted version and inspect origin before retrying:
+For status 3, do not retry or remove the local tag until the remote outcome is
+resolved. ReleaseKit reports the attempted version, tag object, and recovery
+state, including the captured publication endpoint when available. Use that
+endpoint—not merely the current `origin` URL—to query the exact tag; follow the
+upstream
+[failure-recovery procedure](https://gitea.maximumdirect.net/eric/ReleaseKit/src/tag/v0.4.1/docs/release.md#resolve-failures):
 
 ```sh
-git ls-remote --tags origin "refs/tags/$RELEASE_VERSION" "refs/tags/$RELEASE_VERSION^{}"
-git rev-parse "refs/tags/$RELEASE_VERSION" "refs/tags/$RELEASE_VERSION^{}"
+releasekit_endpoint='COPY_CAPTURED_ENDPOINT'
+releasekit_version='vX.Y.Z'
+test "$(git ls-remote --get-url -- "$releasekit_endpoint")" = "$releasekit_endpoint" &&
+  git ls-remote --refs -- "$releasekit_endpoint" "refs/tags/$releasekit_version"
 ```
 
-Matching remote tag and peeled commit values confirm publication, even if the
-push command reported an error. If the remote query fails, publication status
-is still unknown. Do not delete or recreate the local tag until absence on
-origin is confirmed. Once confirmed unpublished, an unsuccessful attempt's
-local tag can be removed and the publication command rerun. Never overwrite
-a published tag.
-
-CI or module-resolution problems may be investigated separately; temporary
-service, network, or authentication failures do not require another release.
-Only an actual defect requiring changes to published contents warrants a new
-appropriate version. See the [recovery policy](policy/release.md#immutability-and-failure-recovery).
+Compare the returned object ID with the reported tag object. An exact match
+confirms publication. A missing ref confirms absence only when the endpoint
+identity check and query both succeed. If either check fails, the outcome
+remains unknown; correct the transport configuration and resolve it before
+retrying. Only after authoritative absence is confirmed may an unpublished
+local tag be removed before correcting the candidate or retrying. Never move,
+overwrite, or delete a published tag.
 
 ## Policy Changes
 

docs/releases/v0.10.0.md

@@ -15,7 +15,7 @@ the existing Go API. This refactor requires no consumer code changes.
 
 This release selects OpenRouter `v2.20260922.1` and Rakestrawhome
 `v2.20260922.0`; their exact inventories are linked from the
-[format reference](../formats.md#external-profile-inventories).
+[migration identity mapping](../consumers/configuration-migration.md#identity-mapping).
 
 The maintained names provide continuity only within the catalog versions
 selected and tested by a Promptkit release and when consumers do not override
@@ -37,8 +37,8 @@ an available profile or supply their own complete definition; the new
 `deepseek-flash-latest` and `deepseek-pro-latest` profiles are not automatic
 aliases and need not preserve the previous settings.
 
-See the [release policy](../release.md#catalog-profile-compatibility) for the
-compatibility boundary, the [format reference](../formats.md#built-in-profile-catalog)
-for current Promptkit-owned definitions and selected external inventories, and
+See the [release policy](../policy/release.md#versioning-and-compatibility) for the
+compatibility boundary, the [migration identity mapping](../consumers/configuration-migration.md#identity-mapping)
+for current resource mappings, and
 the [consumer guide](../consumers/pkg-promptkit.md#choose-a-profile-ownership-model)
 for configuration choices.

docs/releases/v0.11.0.md

@@ -72,5 +72,5 @@ for a structured proposal-and-assessment workflow.
 
 Backend catalog selections are unchanged from v0.10.0: OpenRouter
 `v2.20260922.1` and Rakestrawhome `v2.20260922.0`. See the
-[catalog compatibility policy](../policy/release.md#catalog-profile-compatibility)
-and [profile inventories](../formats.md#external-profile-inventories).
+[release compatibility policy](../policy/release.md#versioning-and-compatibility)
+and [migration identity mapping](../consumers/configuration-migration.md#identity-mapping).

docs/releases/v0.11.1.md

@@ -15,7 +15,7 @@ No public API, runtime behavior, or profile changes are introduced.
 Promptkit remains LGPL-3.0-or-later; the catalogs are now MIT-licensed.
 See the [project grant](../../COPYRIGHT),
 [component attribution](../oss/attribution.md), and
-[catalog compatibility policy](../policy/release.md#catalog-profile-compatibility).
+[release compatibility policy](../policy/release.md#versioning-and-compatibility).
 
 ## Upgrade
 

docs/releases/v0.12.0.md

@@ -35,7 +35,7 @@ for API and source-selection changes.
 Maintained OpenRouter and Rakestrawhome catalogs are selected as `/v3` modules,
 both at `v3.20260930.0`. Their asset format changed; consumers that read catalog
 assets directly must adopt the keyed format. The maintained Promptkit profile
-IDs remain available under the [catalog compatibility policy](../policy/release.md#catalog-profile-compatibility),
+IDs remain available under the [release compatibility policy](../policy/release.md#versioning-and-compatibility),
 which does not promise fixed profile data.
 
 ## Upgrade

docs/releases/v0.13.0.md

@@ -0,0 +1,69 @@
+# Promptkit v0.13.0
+
+This release adds prompt requirement discovery and profile/prompt listing,
+reduces avoidable configuration and execution allocations, and standardizes
+maintainer publication through ReleaseKit. The minimum supported Go version
+increases to 1.26.0.
+
+## Discover Requirements And Available Definitions
+
+- `Engine.InspectRequirements` reports recognizable input and caller-variable
+  dependencies for a selected prompt and supplied caller context before input
+  artifacts exist. It classifies dependencies as required, conditional, or
+  optional and reports structured limitations when discovery is incomplete.
+  Discovery coverage is not proof that requirements are satisfied or execution
+  will succeed. See the [requirement inspection guide](../consumers/pkg-promptkit.md#inspect-requirements-before-preparation)
+  and [GoDoc](../../requirements.go).
+- `Engine.ListProfiles` returns effective profile IDs, and `Engine.ListPrompts`
+  returns exact ID/version pairs as `PromptIdentity` values. Lists come from the
+  engine's captured configuration, are lexically ordered and caller-owned, and
+  include consumer definitions and maintained profiles that remain effective.
+  Listing performs no provider or execution work. See the
+  [discovery guide](../consumers/pkg-promptkit.md#discover-available-resources-and-collections)
+  and [GoDoc](../../listing.go).
+
+## Efficiency And Tooling
+
+- Reduce response-sized copies in basic validation and rendered-message output,
+  and encode valid provider extra parameters only as part of the complete
+  request rather than serializing them twice.
+- Use bounded initial file-size reservations without limiting accepted content,
+  releasing excess backing storage for small or empty completed artifacts.
+- Reuse owned preparation values when creating prepared-execution snapshots,
+  while preserving independent inspection details and caller-owned data.
+- Use lightweight captured profile identities and prompt metadata for inspection
+  instead of copying execution targets and definitions unnecessarily.
+- Upgrade ConfigKit to v0.6.0 for more efficient loading, resolution, metadata,
+  and inspection processing. Configuration semantics remain unchanged; these
+  improvements primarily benefit construction and explicit operator inspection,
+  not upstream inference latency.
+- Adopt module-selected ReleaseKit v0.3.0 for maintainer validation and tag
+  publication. The [release procedure](../release.md) owns the current commands
+  and recovery workflow; successful tag publication remains the completion
+  point, without waiting for CI.
+
+These changes preserve existing execution and ownership contracts. Benefits
+depend on workload; this release introduces no fixed performance guarantee.
+
+## Compatibility And Upgrade
+
+Consumers upgrading from v0.12.0 need **Go 1.26.0 or newer**, rather than the
+previous 1.25.5 minimum. Update application build environments and any CI images
+still using Go 1.25 before upgrading:
+
+```sh
+go get gitea.maximumdirect.net/eric/promptkit@v0.13.0
+```
+
+No application-code or configuration migration is required from v0.12.0 beyond
+the Go toolchain update. The new discovery methods are optional additions;
+existing construction, inspection, preparation, and execution workflows remain
+available. See [Go compatibility](../consumers/pkg-promptkit.md#go-compatibility)
+for the distinction between the consumer minimum and maintainer toolchain.
+
+Maintainers should follow the current release runbook rather than the retired
+`scripts/release-check.sh`. The publication entry point remains
+`scripts/release.sh`; ReleaseKit now owns its shared validation and publication
+mechanics.
+
+[COPYRIGHT](https://gitea.maximumdirect.net/eric/promptkit/src/tag/v0.13.0/COPYRIGHT) | [LICENSE](https://gitea.maximumdirect.net/eric/promptkit/src/tag/v0.13.0/LICENSE) | [ATTRIBUTION](https://gitea.maximumdirect.net/eric/promptkit/src/tag/v0.13.0/docs/oss/attribution.md)

docs/releases/v0.14.0.md

@@ -0,0 +1,48 @@
+# Promptkit v0.14.0
+
+This release adds comparison of captured configuration inspections and updates
+ConfigKit and the maintainer release tool. The minimum supported Go version
+remains 1.26.0.
+
+## Compare Captured Configurations
+
+`ConfigurationInspection.Diff` compares the effective configuration captured by
+two engines. Consumers can use it to review a candidate configuration, inspect
+an overlay's effect, or present configuration changes to operators.
+
+Comparison delegates to ConfigKit and returns its difference records, including
+presence information, paired redaction, and protected-change indicators. It
+does not reload sources or contact providers. Source-history differences alone
+do not produce value differences.
+
+An empty diff is not proof of equivalent execution: referenced file contents,
+resolved credentials, later execution preparation, and request-specific
+overrides are outside the comparison. Records can contain ordinary application
+data; callers retain responsibility for their disclosure.
+
+See the [configuration comparison guide](../consumers/pkg-promptkit.md#inspect-the-captured-configuration)
+and [GoDoc](../../configuration_inspection.go) for usage and the exact contract.
+
+## Dependency And Tooling Updates
+
+- Upgrade ConfigKit from v0.6.0 to v0.7.1, providing the upstream comparison API.
+  v0.7.1 also updates ConfigKit's maintainer tooling without changing its runtime
+  behavior from v0.7.0.
+- Upgrade the module-selected ReleaseKit tool from v0.3.0 to v0.4.1. Promptkit
+  retains its existing root-module profile, publication entry point, and release
+  gates. See the [release procedure](../release.md) for maintainer commands.
+
+## Compatibility And Upgrade
+
+No application-code, configuration, or Go-toolchain migration is required from
+v0.13.0. Configuration comparison is an optional API addition; existing
+construction, inspection, preparation, and execution workflows remain available.
+
+```sh
+go get gitea.maximumdirect.net/eric/promptkit@v0.14.0
+```
+
+See [Go compatibility](../consumers/pkg-promptkit.md#go-compatibility) for the
+distinction between the consumer minimum and maintainer toolchain.
+
+[COPYRIGHT](https://gitea.maximumdirect.net/eric/promptkit/src/tag/v0.14.0/COPYRIGHT) | [LICENSE](https://gitea.maximumdirect.net/eric/promptkit/src/tag/v0.14.0/LICENSE) | [ATTRIBUTION](https://gitea.maximumdirect.net/eric/promptkit/src/tag/v0.14.0/docs/oss/attribution.md)

docs/releases/v0.15.0.md

@@ -0,0 +1,34 @@
+# Promptkit v0.15.0
+
+This release adds error-only validation of a concrete prompt request without
+calling a model. The minimum supported Go version remains 1.26.0.
+
+## Validate A Concrete Request
+
+`Engine.ValidateRequest` accepts an ordinary `RunRequest` and returns nil when
+it passes preparation, or the existing preparation error. Consumers can use it
+for fail-fast checks, including downstream CLI validation commands, without
+receiving a prepared snapshot.
+
+The method shares `Prepare`'s request conversion and preparation path. Unlike
+requirements inspection, it checks the actual supplied values and bindings.
+Artifact and schema resource I/O still occurs; success does not certify provider
+acceptance or later execution success. A subsequent run prepares independently.
+Validation is optional, not a required step before preparation or execution.
+
+See the [request validation guide](../consumers/pkg-promptkit.md#validate-a-concrete-request)
+and [GoDoc](../../engine.go) for usage and the exact contract. Consumers that
+need execution tied to a checked snapshot can use the existing
+[prepared execution workflow](../consumers/pkg-promptkit.md#prepare-now-and-execute-the-same-snapshot-later).
+
+## Compatibility And Upgrade
+
+No application-code, configuration, or Go-toolchain migration is required from
+v0.14.0. This is an optional API addition; existing inspection, preparation, and
+execution workflows remain available.
+
+```sh
+go get gitea.maximumdirect.net/eric/promptkit@v0.15.0
+```
+
+[COPYRIGHT](https://gitea.maximumdirect.net/eric/promptkit/src/tag/v0.15.0/COPYRIGHT) | [LICENSE](https://gitea.maximumdirect.net/eric/promptkit/src/tag/v0.15.0/LICENSE) | [ATTRIBUTION](https://gitea.maximumdirect.net/eric/promptkit/src/tag/v0.15.0/docs/oss/attribution.md)

docs/releases/v0.16.0.md

@@ -0,0 +1,86 @@
+# Promptkit v0.16.0
+
+This release adds explicit smoke diagnostics, configuration collections,
+namespace-scoped engine views, and expanded resource discovery. It also makes
+intentional breaking changes to configuration ownership and prompt selection.
+The minimum supported Go version remains 1.26.0.
+
+## Configuration Collections And Discovery
+
+Applications can compose caller-selected collections of backends, profiles,
+and prompts. Collection resources have qualified identities such as
+`support/answer`; root resources retain unqualified identities. `CollectionInput`
+provides a convenience for mounting a selected ConfigKit input into a collection.
+Promptkit now uses ConfigKit v0.8.0, including its optional source specification
+header support.
+
+`Engine.WithNamespaces` creates an immutable view with separate prompt, profile,
+and backend scopes for short caller-supplied IDs. Views share the underlying
+configuration, clients, capacity pools, and prepared-execution owner. Explicitly
+qualified IDs and configured references keep their exact identities.
+
+`ListProfiles` and `ListPrompts` support namespace filters. New `ListBackends`,
+`ListNamespaces`, and `ListCollections` methods expose captured resource and
+collection inventories. See the [collection format](../formats.md#source-headers-collections-and-resource-ids),
+[scoped-view guide](../consumers/pkg-promptkit.md#use-scoped-engine-views), and
+[discovery guide](../consumers/pkg-promptkit.md#discover-available-resources-and-collections).
+
+## Explicit Smoke Diagnostics
+
+`Engine.SmokeTest` provides backend reachability, authentication, text inference,
+and structured-output inference diagnostics. Reports provide factual
+observations, timing, and available usage rather than an overall readiness
+verdict. Optional Boolean facts distinguish negative observations from unknown
+or inapplicable checks; matching a JSON schema does not prove that a provider
+enforced it.
+
+A concluded diagnostic can report failure with a nil Go error. Invalid requests
+return ordinary errors, and caller cancellation can return partial observations
+with a recognizable context error. Diagnostics can contact providers and incur
+inference costs only when explicitly invoked; they are not automatic execution
+or release checks. See the [smoke diagnostic guide](../consumers/pkg-promptkit.md#run-explicit-smoke-diagnostics)
+and [API GoDoc](../../smoke_diagnostics.go).
+
+## Breaking Changes And Upgrade
+
+Consumers upgrading from v0.15.0 should follow the
+[configuration and API migration guide](../consumers/configuration-migration.md):
+
+- Supply backend and profile definitions explicitly. Promptkit no longer bundles
+  provider catalogs or the `promptkit-openrouter-standard` and
+  `promptkit-openrouter-auto` profiles. Conventional backend names do not install
+  definitions automatically. Applications choose and maintain their sources.
+- Convert version-keyed prompt mappings into one definition per prompt ID.
+  Prompt `version` is now an optional descriptive label, not a selector.
+  Choose deliberately which former definition to install.
+- Remove `PromptVersion` selectors from `RunRequest`,
+  `RequirementInspectionRequest`, and `SmokeTestRequest`, where applicable.
+  Change prompt inspection calls to `InspectPrompt(ctx, promptID)`. Update code
+  consuming version-bearing inspection, identity, result, or observation fields
+  to handle optional labels, including nil and explicitly empty labels.
+- When moving resources into collections, update stored backend, profile, and
+  diagnostic-default references to their intended qualified IDs. Mounting a
+  source does not rewrite references; profile inheritance remains within its
+  sibling mapping. Root configuration `version`, when supplied, is now a source
+  specification header, distinct from descriptive resource labels.
+
+The migration guide includes identity mappings and before/after prompt examples.
+The [maintained offline example](../../examples/go-library/prepare/main.go)
+demonstrates explicit composition, source-relative content, scoped preparation,
+and inventory without contacting a provider.
+
+After adapting configuration and API calls:
+
+```sh
+go get gitea.maximumdirect.net/eric/promptkit@v0.16.0
+```
+
+## Correctness And Efficiency
+
+Collection prompt materialization shares one lazy origin-metadata snapshot,
+avoiding repeated full metadata copies across collections. Internal prepared
+snapshots detach optional prompt labels. Smoke diagnostics preserve caller
+cancellation and report actual inference destinations and known-zero usage when
+no generation request was dispatched.
+
+[COPYRIGHT](https://gitea.maximumdirect.net/eric/promptkit/src/tag/v0.16.0/COPYRIGHT) | [LICENSE](https://gitea.maximumdirect.net/eric/promptkit/src/tag/v0.16.0/LICENSE) | [ATTRIBUTION](https://gitea.maximumdirect.net/eric/promptkit/src/tag/v0.16.0/docs/oss/attribution.md)

docs/releases/v0.7.0.md

@@ -63,8 +63,8 @@ Every engine now includes the reserved `rakestrawhome` backend, identified by
 selects that backend. Consumers can use the maintained endpoint, credential,
 capacity, and model defaults without registering either definition themselves.
 
-See the [built-in backend and profile catalogs](../formats.md#built-in-backends)
-and the [consumer adoption example](../consumers/pkg-promptkit.md#use-the-rakestrawhome-built-in-profile)
+See the [backend format reference](../formats.md#backend-definitions)
+and the [current identity migration mapping](../consumers/configuration-migration.md#identity-mapping)
 for the current contracts.
 
 ## Structured Generation Errors
@@ -127,7 +127,7 @@ freezes the fully resolved target. The selected leaf ID remains public while
 effective execution settings reflect the resolved chain.
 
 See the [profile inheritance format reference](../formats.md#profile-inheritance),
-the [consumer alias example](../consumers/pkg-promptkit.md#alias-a-built-in-profile),
+the [current identity migration mapping](../consumers/configuration-migration.md#identity-mapping),
 and the [`Profile` GoDoc](../../types.go) for exact merge and validation
 behavior.
 

docs/releases/v0.9.0.md

@@ -96,9 +96,8 @@ precedence rules. Promptkit no longer keeps duplicate embedded profile assets
 or hard-coded definitions for those maintained backends.
 
 The module versions in Promptkit's `go.mod` identify the catalog releases
-tested with this release. The [built-in backend and profile format
-reference](../formats.md#built-in-backends) remains the canonical consumer
-contract, while the [internal source documentation](../internal/sources.md#profiles-and-built-ins)
+tested with this release. The [backend format reference](../formats.md#backend-definitions)
+remains the canonical consumer contract, while the [internal source documentation](../internal/sources.md#profiles)
 describes the dependency boundary.
 
 ## Public API Changes

engine.go

@@ -24,9 +24,8 @@ var (
 	// ErrInvalidRequest identifies a request whose required values, overrides,
 	// credentials, or effective settings are invalid.
 	ErrInvalidRequest = errors.New("invalid run request")
-	// ErrPromptNotFound identifies a requested prompt ID or version that is not
-	// present in the selected prompt source. It does not also match
-	// ErrPromptLoad.
+	// ErrPromptNotFound identifies a requested prompt ID that is not present in
+	// the captured configuration. It does not also match ErrPromptLoad.
 	ErrPromptNotFound = errors.New("prompt not found")
 	// ErrProfileNotFound identifies a selected profile ID that is absent from
 	// every configured profile source. It does not also match ErrProfileLoad.
@@ -82,16 +81,21 @@ var (
 	ErrValidation = errors.New("failed to validate output")
 )
 
-// Engine inspects prompts and profiles and prepares and runs Promptkit prompt
-// requests.
+// Engine inspects prompts and profiles, enumerates prompt requirements, and
+// prepares and runs Promptkit prompt requests.
 //
-// An Engine is safe for concurrent calls to [Engine.InspectConfiguration],
+// An Engine is safe for concurrent calls to [Engine.WithNamespaces],
+// [Engine.InspectConfiguration],
 // [Engine.InspectPrompt],
-// [Engine.InspectProfile], [Engine.Prepare], [Engine.PrepareExecution],
-// [Engine.Run], and [Engine.RunPrepared]. Each Engine owns independent
-// backend-capacity pools that coordinate Run and RunPrepared admission and
-// model generation. Injected collaborators may still be invoked concurrently
-// across different backend pools or for unlimited backends.
+// [Engine.InspectRequirements], [Engine.InspectProfile], [Engine.Prepare], [Engine.PrepareExecution],
+// [Engine.Run], [Engine.RunPrepared], [Engine.SmokeTest], [Engine.ListProfiles],
+// [Engine.ListPrompts], [Engine.ListBackends], [Engine.ListNamespaces], and
+// [Engine.ListCollections]. Engines constructed separately by [NewEngine] own
+// independent backend-capacity pools that coordinate Run, RunPrepared, and
+// inference SmokeTest admission and model generation. Namespace views returned
+// by [Engine.WithNamespaces] share their underlying engine's pools, clients,
+// and prepared-execution owner. Injected collaborators may still be invoked
+// concurrently across different backend pools or for unlimited backends.
 type Engine struct {
 	internal *internalengine.Engine
 }
@@ -208,11 +212,11 @@ func WithSchemaFile(path string) Option {
 
 // NewEngine constructs an Engine from configuration and options.
 //
-// ConfigKit composes maintained catalog inputs, PromptKit-owned definitions,
-// caller underlays, and the optional main input in that order. Construction
-// validates the final effective backend, profile, and prompt definitions and
-// captures referenced prompt content. A missing prompt collection is allowed.
-// Schema documents and request artifacts remain runtime resources.
+// ConfigKit composes caller-selected underlays in their given order, followed
+// by the optional main input. Construction validates the final effective
+// backend, profile, and prompt definitions and captures referenced prompt
+// content. A missing prompt collection is allowed. Schema documents and
+// request artifacts remain runtime resources.
 //
 // NewEngine returns an error matching ErrInvalidConfig for invalid
 // configuration or options, preserving a ConfigKit LoadError when loading
@@ -241,14 +245,13 @@ func NewEngine(cfg Config, opts ...Option) (*Engine, error) {
 	return &Engine{internal: assembled}, nil
 }
 
-// InspectPrompt resolves one explicit prompt definition without selecting a
-// profile or starting execution work.
+// InspectPrompt resolves one prompt ID without selecting a profile or starting
+// execution work.
 //
-// InspectPrompt requires a nonblank promptID. It passes nonblank promptID and
-// promptVersion values unchanged to the engine's ordinary, case-sensitive
-// prompt selection. An empty version succeeds only when that ID has one
-// version; a nonempty version selects one exact ID/version pair from the
-// captured configuration snapshot.
+// InspectPrompt requires a nonblank promptID and performs an exact,
+// case-sensitive lookup in the captured configuration snapshot. A
+// namespace-scoped view qualifies slashless caller IDs before lookup; already
+// qualified IDs pass through. Prompt version labels do not select definitions.
 //
 // A successful result proves that the selected definition and any referenced
 // message content files were structurally loaded. Inputs are returned in
@@ -267,21 +270,19 @@ func NewEngine(cfg Config, opts ...Option) (*Engine, error) {
 // or content files; construct another Engine to observe source changes.
 //
 // A nil Engine returns an error matching ErrInvalidConfig. A blank prompt ID
-// matches ErrInvalidRequest. An absent exact ID or version matches
-// ErrPromptNotFound and not ErrPromptLoad. An ambiguous omitted version matches
-// ErrPromptLoad. Invalid definitions and resource failures reject construction
-// instead. Cancellation during lookup preserves the context error. InspectPrompt
-// returns no partial result on error.
+// matches ErrInvalidRequest. An absent exact ID matches ErrPromptNotFound and
+// not ErrPromptLoad. Invalid definitions and resource failures reject
+// construction instead. Cancellation during lookup preserves the context
+// error. InspectPrompt returns no partial result on error.
 func (e *Engine) InspectPrompt(
 	ctx context.Context,
 	promptID string,
-	promptVersion string,
 ) (*PromptInspection, error) {
 	if e == nil || e.internal == nil {
 		return nil, fmt.Errorf("%w: engine is nil", ErrInvalidConfig)
 	}
 
-	inspection, err := e.internal.InspectPrompt(ctx, promptID, promptVersion)
+	inspection, err := e.internal.InspectPrompt(ctx, promptID)
 	if err != nil {
 		return nil, mapPublicError(err)
 	}
@@ -346,6 +347,32 @@ func (e *Engine) InspectProfile(ctx context.Context, profileID string) (*Profile
 // relationship to ctx.Err is promised. Prepare returns no partial result on
 // error. It validates RunRequest.TransientRetries but makes no model attempts.
 func (e *Engine) Prepare(ctx context.Context, req RunRequest) (*PreparedRun, error) {
+	prepared, err := e.prepareRequest(ctx, req)
+	if err != nil {
+		return nil, err
+	}
+	return fromDomainPreparedRun(prepared), nil
+}
+
+// ValidateRequest reports whether req passes the same preparation path used by
+// [Engine.Prepare] at the time of this call. A nil error means this concrete
+// request passed preparation. It checks only this invocation and returns errors
+// as encountered rather than aggregating them. All supplied inputs follow the
+// same loading behavior as [Engine.Prepare], including inputs unused by the
+// selected template branch. The method does not call an LLM or retain a
+// prepared snapshot or executable handle, but preparation may still perform
+// resource I/O and incur its associated time and memory costs.
+//
+// Its errors and context handling follow [Engine.Prepare], including an error
+// matching ErrInvalidConfig when the Engine is nil. Success does not guarantee
+// provider acceptance or later execution success. Use [Engine.PrepareExecution]
+// when execution must use the snapshot produced by preparation.
+func (e *Engine) ValidateRequest(ctx context.Context, req RunRequest) error {
+	_, err := e.prepareRequest(ctx, req)
+	return err
+}
+
+func (e *Engine) prepareRequest(ctx context.Context, req RunRequest) (*domain.PreparedRun, error) {
 	ctx = observation.WithoutExecutionState(ctx)
 	if e == nil || e.internal == nil {
 		return nil, fmt.Errorf("%w: engine is nil", ErrInvalidConfig)
@@ -360,15 +387,16 @@ func (e *Engine) Prepare(ctx context.Context, req RunRequest) (*PreparedRun, err
 	if err != nil {
 		return nil, mapPublicError(err)
 	}
-	return fromDomainPreparedRun(prepared), nil
+	return prepared, nil
 }
 
 // PrepareExecution completely prepares a prompt request without calling the
 // configured LLMClient or reserving backend admission capacity. Validated
 // RunRequest.AppendedMessages are included in the frozen effective messages.
 //
-// The returned opaque handle is bound to this Engine and permits one
-// [Engine.RunPrepared] invocation. Preparation freezes the selected sources,
+// The returned opaque handle is bound to this Engine's underlying execution
+// owner, shared with its namespace views, and permits one [Engine.RunPrepared]
+// invocation in total. Preparation freezes the selected sources,
 // rendered messages, effective settings, inputs, provider structured-output
 // metadata, and validation resources needed by that invocation. The handle
 // retains a direct RunRequest.APIKey only in private execution state;
@@ -480,6 +508,11 @@ func (e *Engine) run(ctx context.Context, req RunRequest) (*RunResult, error) {
 // RunPrepared atomically claims and executes a handle created by
 // [Engine.PrepareExecution].
 //
+// The originating Engine and namespace views sharing its underlying owner may
+// claim the handle. Execution uses its captured selections without applying the
+// invoking view's namespaces. An Engine constructed separately by [NewEngine]
+// is a foreign owner.
+//
 // A valid owning-Engine invocation consumes the handle's one attempt before
 // credential revalidation, backend admission, generation, or validation.
 // Cancellation, capacity rejection, generation failure, operational

examples/go-library/observe/prompts/assessment.yaml

@@ -1,18 +1,18 @@
 prompts:
   example.assessment:
-    "1.0.0":
-      default_profile: assessment-profile
-      description: Assess a structured proposal independently of schema validity.
-      inputs:
-        - name: proposal
-          required: true
-          content_type: application/json
-      messages:
-        - role: system
-          content: Return a concise assessment as JSON.
-        - role: user
-          content: '{{input "proposal"}}'
-      output:
-        format: json
-        validation_mode: json_schema
-        schema_path: assessment.schema.json
+    version: "1.0.0"
+    default_profile: assessment-profile
+    description: Assess a structured proposal independently of schema validity.
+    inputs:
+      - name: proposal
+        required: true
+        content_type: application/json
+    messages:
+      - role: system
+        content: Return a concise assessment as JSON.
+      - role: user
+        content: '{{input "proposal"}}'
+    output:
+      format: json
+      validation_mode: json_schema
+      schema_path: assessment.schema.json

examples/go-library/observe/prompts/proposal.yaml

@@ -1,18 +1,18 @@
 prompts:
   example.proposal:
-    "1.0.0":
-      default_profile: proposal-profile
-      description: Propose a bounded improvement from a synthetic idea.
-      inputs:
-        - name: idea
-          required: true
-          content_type: text/plain
-      messages:
-        - role: system
-          content: Return a concise proposal as JSON.
-        - role: user
-          content: '{{input "idea"}}'
-      output:
-        format: json
-        validation_mode: json_schema
-        schema_path: proposal.schema.json
+    version: "1.0.0"
+    default_profile: proposal-profile
+    description: Propose a bounded improvement from a synthetic idea.
+    inputs:
+      - name: idea
+        required: true
+        content_type: text/plain
+    messages:
+      - role: system
+        content: Return a concise proposal as JSON.
+      - role: user
+        content: '{{input "idea"}}'
+    output:
+      format: json
+      validation_mode: json_schema
+      schema_path: proposal.schema.json

examples/go-library/prepare/collections/review/collection.yaml

@@ -0,0 +1,17 @@
+backends:
+  offline:
+    endpoint: https://review.example.invalid/v1
+profiles:
+  audit:
+    backend: review/offline
+    model: review-model
+prompts:
+  check:
+    default_profile: review/audit
+    description: Inspect a review item without contacting a model provider.
+    messages:
+      - role: user
+        content: Review the supplied synthetic example.
+    output:
+      format: text
+      validation_mode: none

examples/go-library/prepare/collections/support/collection.yaml

@@ -0,0 +1,5 @@
+version: "1"
+configkit:
+  imports:
+    - path: fragments/resources.yaml
+release_version: "1.4.0"

examples/go-library/prepare/collections/support/fragments/resources.yaml

@@ -0,0 +1,28 @@
+backends:
+  offline:
+    endpoint: https://example.invalid/v1
+profiles:
+  base:
+    backend: support/offline
+    model: offline-model
+    timeout_seconds: 90
+  fast:
+    extends: base
+    timeout_seconds: 60
+prompts:
+  prepare:
+    version: "1.0.0"
+    default_profile: support/fast
+    description: Prepare a prompt without contacting a model provider.
+    inputs:
+      - name: note
+        required: true
+        content_type: text/plain
+    messages:
+      - role: system
+        content: Summarize the note in one sentence.
+      - role: user
+        content_file: ../messages/note.md
+    output:
+      format: text
+      validation_mode: basic

examples/go-library/prepare/collections/support/messages/note.md

@@ -0,0 +1 @@
+{{input "note"}}

examples/go-library/prepare/collections/support/operator-overrides.yaml

@@ -0,0 +1,4 @@
+# A later input intentionally replaces only the inherited profile timeout.
+profiles:
+  fast:
+    timeout_seconds: 30

examples/go-library/prepare/main.go

@@ -11,41 +11,138 @@ import (
 )
 
 type summary struct {
-	PromptID        string `json:"prompt_id"`
-	PromptVersion   string `json:"prompt_version"`
-	SelectedProfile string `json:"selected_profile"`
-	Model           string `json:"model"`
-	MessageCount    int    `json:"message_count"`
+	PromptID        string              `json:"prompt_id"`
+	PromptVersion   *string             `json:"prompt_version,omitempty"`
+	SelectedProfile string              `json:"selected_profile"`
+	Model           string              `json:"model"`
+	MessageCount    int                 `json:"message_count"`
+	ProfileTimeout  int                 `json:"profile_timeout_seconds"`
+	Namespaces      []string            `json:"namespaces"`
+	Collections     []collectionSummary `json:"collections"`
+	ScopedPrompts   []string            `json:"scoped_prompts"`
+	ReviewPrompts   []string            `json:"review_prompts"`
+}
+
+type collectionSummary struct {
+	Namespace      string  `json:"namespace"`
+	ReleaseVersion *string `json:"release_version"`
 }
 
 func main() {
-	endpoint, model := "https://example.invalid/v1", "offline-model"
+	support, err := promptkit.CollectionInput(
+		"support",
+		configkit.File("examples/go-library/prepare/collections/support/collection.yaml"),
+	)
+	if err != nil {
+		exit(err)
+	}
+	review, err := promptkit.CollectionInput(
+		"review",
+		configkit.File("examples/go-library/prepare/collections/review/collection.yaml"),
+	)
+	if err != nil {
+		exit(err)
+	}
+	override, err := promptkit.CollectionInput(
+		"support",
+		configkit.File("examples/go-library/prepare/collections/support/operator-overrides.yaml"),
+	)
+	if err != nil {
+		exit(err)
+	}
 	engine, err := promptkit.NewEngine(promptkit.Config{Sources: promptkit.ConfigurationSources{
-		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{{Source: promptkit.ProfileSource("example profile", map[string]promptkit.ProfileConfig{
-			"offline-example": {Endpoint: &endpoint, Model: &model},
-		})}}}},
-		Main: &configkit.Input{Source: configkit.File("examples/go-library/prepare/prompt.yaml")},
+		Underlays: []configkit.Underlay{
+			{Inputs: []configkit.Input{support, review}},
+			{Inputs: []configkit.Input{override}},
+		},
 	}})
 	if err != nil {
 		exit(err)
 	}
+	ctx := context.Background()
+	scoped, err := engine.WithNamespaces(promptkit.Namespaces{
+		Prompt: "support", Profile: "support", Backend: "support",
+	})
+	if err != nil {
+		exit(err)
+	}
 	view, err := engine.InspectConfiguration()
 	if err != nil {
 		exit(err)
 	}
-	if _, found := view.Explain(configkit.Keys("profiles", "offline-example", "model")); !found {
-		exit(fmt.Errorf("configured profile model was not found"))
+	if _, found := view.Explain(configkit.Keys(
+		"collections", "support", "profiles", "fast", "timeout_seconds",
+	)); !found {
+		exit(fmt.Errorf("collection profile override was not found"))
 	}
-
-	prepared, err := engine.Prepare(context.Background(), promptkit.RunRequest{
-		PromptID: "example.prepare",
-		Inputs: map[string]promptkit.ArtifactRef{
-			"note": promptkit.Inline("Ada finished the migration review."),
-		},
+	requirements, err := scoped.InspectRequirements(ctx, promptkit.RequirementInspectionRequest{
+		PromptID: "prepare",
 	})
 	if err != nil {
 		exit(err)
 	}
+	if !requirements.Complete || len(requirements.Inputs) != 1 ||
+		requirements.Inputs[0].Name != "note" ||
+		requirements.Inputs[0].Kind != promptkit.RequirementRequired {
+		exit(fmt.Errorf("required note input was not discovered before preparation"))
+	}
+
+	request := promptkit.RunRequest{
+		PromptID:  "prepare",
+		ProfileID: "fast",
+		Inputs: map[string]promptkit.ArtifactRef{
+			"note": promptkit.Inline("Ada finished the migration review."),
+		},
+	}
+	if err := scoped.ValidateRequest(ctx, request); err != nil {
+		exit(err)
+	}
+	prepared, err := scoped.Prepare(ctx, request)
+	if err != nil {
+		exit(err)
+	}
+	profile, err := scoped.InspectProfile(ctx, "fast")
+	if err != nil {
+		exit(err)
+	}
+	if profile.EffectiveModelParams.TimeoutSeconds != 30 {
+		exit(fmt.Errorf(
+			"later profile override was not applied: timeout is %d seconds",
+			profile.EffectiveModelParams.TimeoutSeconds,
+		))
+	}
+	namespaces, err := scoped.ListNamespaces(ctx)
+	if err != nil {
+		exit(err)
+	}
+	collections, err := scoped.ListCollections(ctx)
+	if err != nil {
+		exit(err)
+	}
+	scopedPrompts, err := scoped.ListPrompts(ctx)
+	if err != nil {
+		exit(err)
+	}
+	reviewPrompts, err := scoped.ListPrompts(ctx, promptkit.NamespaceFilter{
+		Mode: promptkit.NamespaceNamed, Name: "review",
+	})
+	if err != nil {
+		exit(err)
+	}
+	scopedPromptIDs := make([]string, len(scopedPrompts))
+	for index := range scopedPrompts {
+		scopedPromptIDs[index] = scopedPrompts[index].ID
+	}
+	reviewPromptIDs := make([]string, len(reviewPrompts))
+	for index := range reviewPrompts {
+		reviewPromptIDs[index] = reviewPrompts[index].ID
+	}
+	collectionSummaries := make([]collectionSummary, len(collections))
+	for index := range collections {
+		collectionSummaries[index] = collectionSummary{
+			Namespace: collections[index].Namespace, ReleaseVersion: collections[index].ReleaseVersion,
+		}
+	}
 
 	encoder := json.NewEncoder(os.Stdout)
 	encoder.SetIndent("", "  ")
@@ -55,6 +152,11 @@ func main() {
 		SelectedProfile: prepared.SelectedProfileID,
 		Model:           prepared.EffectiveModelParams.Model,
 		MessageCount:    len(prepared.Messages),
+		ProfileTimeout:  profile.EffectiveModelParams.TimeoutSeconds,
+		Namespaces:      namespaces,
+		Collections:     collectionSummaries,
+		ScopedPrompts:   scopedPromptIDs,
+		ReviewPrompts:   reviewPromptIDs,
 	}); err != nil {
 		exit(err)
 	}

examples/go-library/prepare/prompt.yaml

@@ -1,17 +0,0 @@
-prompts:
-  example.prepare:
-    "1.0.0":
-      default_profile: offline-example
-      description: Prepare a prompt without contacting a model provider.
-      inputs:
-        - name: note
-          required: true
-          content_type: text/plain
-      messages:
-        - role: system
-          content: Summarize the note in one sentence.
-        - role: user
-          content: '{{input "note"}}'
-      output:
-        format: text
-        validation_mode: basic

examples/go-library/run/prompt.yaml

@@ -1,17 +1,17 @@
 prompts:
   example.run:
-    "1.0.0":
-      default_profile: offline-example
-      description: Run a prompt with a deterministic injected model client.
-      inputs:
-        - name: note
-          required: true
-          content_type: text/plain
-      messages:
-        - role: system
-          content: Summarize the note in one sentence.
-        - role: user
-          content: '{{input "note"}}'
-      output:
-        format: text
-        validation_mode: basic
+    version: "1.0.0"
+    default_profile: offline-example
+    description: Run a prompt with a deterministic injected model client.
+    inputs:
+      - name: note
+        required: true
+        content_type: text/plain
+    messages:
+      - role: system
+        content: Summarize the note in one sentence.
+      - role: user
+        content: '{{input "note"}}'
+    output:
+      format: text
+      validation_mode: basic

formatting.go

@@ -18,9 +18,8 @@ func (r RunRequest) GoString() string {
 
 func (r RunRequest) redactedString() string {
 	return fmt.Sprintf(
-		"promptkit.RunRequest{PromptID:%q PromptVersion:%q ProfileID:%q APIKeySet:%t Inputs:%d Vars:%d ExecutionSet:%t ValidationSet:%t AppendedMessages:%d}",
+		"promptkit.RunRequest{PromptID:%q ProfileID:%q APIKeySet:%t Inputs:%d Vars:%d ExecutionSet:%t ValidationSet:%t AppendedMessages:%d}",
 		r.PromptID,
-		r.PromptVersion,
 		r.ProfileID,
 		r.APIKey != "",
 		len(r.Inputs),

frozen_rendering_contract_test.go

@@ -19,15 +19,15 @@ import (
 const capturedPromptDocument = `
 prompts:
   captured:
-    "1":
-      default_profile: offline
-      session_id: '{{.session}}'
-      messages:
-        - role: user
-          content_file: body.tmpl
-      output:
-        format: text
-        validation_mode: none
+    version: "1"
+    default_profile: offline
+    session_id: '{{.session}}'
+    messages:
+      - role: user
+        content_file: body.tmpl
+    output:
+      format: text
+      validation_mode: none
 `
 
 func capturedPromptEngine(t *testing.T, source fs.FS) *promptkit.Engine {
@@ -149,12 +149,13 @@ func TestPreparationStillReadsRequestArtifactsAndSchemasAfterConstruction(t *tes
 			"offline": {Endpoint: &endpoint, Model: &model},
 		})}}}},
 		Main: &configkit.Input{Source: configkit.Mapping("structured prompt", map[string]any{
-			"prompts": map[string]any{"structured": map[string]any{"1": map[string]any{
+			"prompts": map[string]any{"structured": map[string]any{
+				"version":         "1",
 				"default_profile": "offline",
 				"inputs":          []any{map[string]any{"name": "note", "required": true}},
 				"messages":        []any{map[string]any{"role": "user", "content": `{{input "note"}}`}},
 				"output":          map[string]any{"format": "json", "validation_mode": "json_schema", "schema_path": "schema.json"},
-			}}},
+			}},
 		})},
 	}}, promptkit.WithSchemaFS(schemas, "."))
 	if err != nil {

go.mod

@@ -1,15 +1,18 @@
 module gitea.maximumdirect.net/eric/promptkit
 
-go 1.25.5
+go 1.26.0
 
 require (
-	gitea.maximumdirect.net/eric/ConfigKit v0.5.0
-	gitea.maximumdirect.net/eric/promptkit-backend-openrouter/v3 v3.20260930.0
-	gitea.maximumdirect.net/eric/promptkit-backend-rakestrawhome/v3 v3.20260930.0
+	gitea.maximumdirect.net/eric/ConfigKit v0.8.0
 	github.com/santhosh-tekuri/jsonschema/v6 v6.0.2
 )
 
 require (
+	gitea.maximumdirect.net/eric/ReleaseKit v0.4.1 // indirect
+	github.com/yuin/goldmark/v2 v2.1.6 // indirect
 	go.yaml.in/yaml/v4 v4.0.0-rc.6 // indirect
+	golang.org/x/mod v0.40.0 // indirect
 	golang.org/x/text v0.14.0 // indirect
 )
+
+tool gitea.maximumdirect.net/eric/ReleaseKit/cmd/releasekit

go.sum

@@ -1,16 +1,16 @@
-gitea.maximumdirect.net/eric/ConfigKit v0.5.0 h1:2KwG10+kApWM3avOoYA+p768xcbHUp7tQ2rqizBNpyg=
-gitea.maximumdirect.net/eric/ConfigKit v0.5.0/go.mod h1:tYWpsrbLyu05r8+1MapWp5fN6ZrX9I8hU2xEPedYmYk=
-gitea.maximumdirect.net/eric/promptkit-backend-openrouter/v3 v3.20260930.0 h1:lzfCDbzJQRGzIlRPRprnAV9hVVL5zUQy80VMQ0kbYa0=
-gitea.maximumdirect.net/eric/promptkit-backend-openrouter/v3 v3.20260930.0/go.mod h1:HjS0f+3q0IdHCTEz+VVAEgIwIWJFAZUjuKdAtvtqKdg=
-gitea.maximumdirect.net/eric/promptkit-backend-rakestrawhome/v3 v3.20260930.0 h1:h12ZTRldAmpLAomj0oQRGteFxHLN1LPE6XDl9zJNbm8=
-gitea.maximumdirect.net/eric/promptkit-backend-rakestrawhome/v3 v3.20260930.0/go.mod h1:OEFBeKdjTsLzqJwLmXI2O5gG3r64FktcVJVb3mBrRfg=
+gitea.maximumdirect.net/eric/ConfigKit v0.8.0 h1:xCIhYnOHjw7rFvB+vIremPKGeROOxKTomnUEUipuQno=
+gitea.maximumdirect.net/eric/ConfigKit v0.8.0/go.mod h1:C82sbyKHYMV1OwaD2GJanFrwTfcZfjlW2JsGze5b0kA=
+gitea.maximumdirect.net/eric/ReleaseKit v0.4.1 h1:Qn+mdebYOzCVCEXgCbuGSO/WHmJtItwaQ8e3XwY3qtI=
+gitea.maximumdirect.net/eric/ReleaseKit v0.4.1/go.mod h1:LVodqNQ3OIKv9NBq+fFeyMByd1lHY25YOmmpah/NaNI=
 github.com/dlclark/regexp2 v1.11.0 h1:G/nrcoOa7ZXlpoa/91N3X7mM3r8eIlMBBJZvsz/mxKI=
 github.com/dlclark/regexp2 v1.11.0/go.mod h1:DHkYz0B9wPfa6wondMfaivmHpzrQ3v9q8cnmRbL6yW8=
 github.com/santhosh-tekuri/jsonschema/v6 v6.0.2 h1:KRzFb2m7YtdldCEkzs6KqmJw4nqEVZGK7IN2kJkjTuQ=
 github.com/santhosh-tekuri/jsonschema/v6 v6.0.2/go.mod h1:JXeL+ps8p7/KNMjDQk3TCwPpBy0wYklyWTfbkIzdIFU=
+github.com/yuin/goldmark/v2 v2.1.6 h1:igy0q9JcqovoFXFx/XjtU8sHVhcUHavPj2sA3EoKJUE=
+github.com/yuin/goldmark/v2 v2.1.6/go.mod h1:G6M4/qOFtfn01/o14BU1UR2Lo5N3S9Qo7xCuz/sHjGQ=
 go.yaml.in/yaml/v4 v4.0.0-rc.6 h1:1h7H1ohdUh93/FyE4YaDa1Zh64K6VVbjF4K6WUxMtH4=
 go.yaml.in/yaml/v4 v4.0.0-rc.6/go.mod h1:aZqd9kCMsGL7AuUv/m/PvWLdg5sjJsZ4oHDEnfPPfY0=
+golang.org/x/mod v0.40.0 h1:hUv+3cXcdRHz08UmSiOob7sadHig73uo5bkXxQ/tvUs=
+golang.org/x/mod v0.40.0/go.mod h1:0/weTWkPWGBikyTWAX3dkjVztMmBA5hM0DH6BElSupE=
 golang.org/x/text v0.14.0 h1:ScX5w1eTa3QqT8oi6+ziP7dTV1S2+ALU0bI+0zXKWiQ=
 golang.org/x/text v0.14.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU=
-gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
-gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

internal/artifact/reader.go

@@ -21,6 +21,7 @@ var (
 )
 
 const fileReadChunkSize = 64 * 1024
+const fileReadInitialCapacityLimit = 1 << 20
 
 // Reader resolves artifact references into actual artifacts.
 type Reader interface {
@@ -133,7 +134,11 @@ func readFileArtifact(ctx context.Context, path string, open func(string) (artif
 		return nil, fmt.Errorf("%w: %s", ErrUnsupportedFile, path)
 	}
 
-	data := make([]byte, 0)
+	capacity := 0
+	if size := openedInfo.Size(); size > 0 {
+		capacity = int(min(size, int64(fileReadInitialCapacityLimit)))
+	}
+	data := make([]byte, 0, capacity)
 	chunk := make([]byte, fileReadChunkSize)
 	for {
 		if err := ctx.Err(); err != nil {
@@ -153,6 +158,13 @@ func readFileArtifact(ctx context.Context, path string, open func(string) (artif
 			return nil, fmt.Errorf("failed to read file %s: %w", path, readErr)
 		}
 	}
+	if cap(data)-len(data) > len(data) {
+		// A stale size hint should not make a small completed artifact retain a
+		// disproportionately large backing array.
+		compact := make([]byte, len(data))
+		copy(compact, data)
+		data = compact
+	}
 
 	contentType := mime.TypeByExtension(filepath.Ext(path))
 	if contentType == "" {

internal/artifact/reader_benchmark_test.go

@@ -0,0 +1,180 @@
+package artifact
+
+import (
+	"bytes"
+	"context"
+	"crypto/sha256"
+	"fmt"
+	"mime"
+	"os"
+	"path/filepath"
+	"runtime"
+	"testing"
+
+	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
+)
+
+var artifactFileReadBenchmarkSink *domain.Artifact
+
+func BenchmarkArtifactFileRead(b *testing.B) {
+	for _, fixture := range makeArtifactReadBenchmarkFiles(b) {
+		b.Run(fixture.name, func(b *testing.B) {
+			reader := &fileReader{open: openArtifactFile}
+			ref := domain.ArtifactRef{Type: domain.ArtifactRefFile, URI: fixture.path}
+			checkArtifactFileRead(b, reader, ref, fixture.body)
+
+			b.ReportAllocs()
+			b.SetBytes(int64(len(fixture.body)))
+			b.ResetTimer()
+			for range b.N {
+				artifact, err := reader.Read(context.Background(), ref)
+				if err != nil {
+					b.Fatalf("read artifact: %v", err)
+				}
+				artifactFileReadBenchmarkSink = artifact
+			}
+			b.StopTimer()
+			runtime.KeepAlive(artifactFileReadBenchmarkSink)
+		})
+	}
+}
+
+// BenchmarkRetainedArtifactFileRead measures live artifact bodies when an
+// opened file reports a size larger than the content that reaches EOF.
+func BenchmarkRetainedArtifactFileRead(b *testing.B) {
+	for _, fixture := range []struct {
+		name string
+		body []byte
+	}{
+		{name: "small", body: bytes.Repeat([]byte("x"), 256<<10)},
+		{name: "empty", body: []byte{}},
+	} {
+		b.Run(fixture.name, func(b *testing.B) {
+			benchmarkRetainedArtifactFileRead(b, fixture.body)
+		})
+	}
+}
+
+func benchmarkRetainedArtifactFileRead(b *testing.B, body []byte) {
+	path := filepath.Join(b.TempDir(), "overreported.txt")
+	if err := os.WriteFile(path, body, 0o600); err != nil {
+		b.Fatal(err)
+	}
+	mime.TypeByExtension(filepath.Ext(path))
+
+	reader := &fileReader{open: func(path string) (artifactFile, error) {
+		file, err := os.Open(path)
+		if err != nil {
+			return nil, err
+		}
+		return &sizeReportingArtifactFile{artifactFile: file, reportedSize: 16 << 20}, nil
+	}}
+	ref := domain.ArtifactRef{Type: domain.ArtifactRefFile, URI: path}
+	checkArtifactFileRead(b, reader, ref, body)
+
+	const retainedBatchSize = 4
+	retained := make([]*domain.Artifact, retainedBatchSize)
+	artifactFileReadBenchmarkSink = nil
+	runtime.GC()
+	var setupMemory runtime.MemStats
+	runtime.ReadMemStats(&setupMemory)
+	runtime.KeepAlive(reader)
+	runtime.KeepAlive(ref)
+
+	b.ReportAllocs()
+	b.SetBytes(int64(len(body)))
+	b.ResetTimer()
+	for iteration := 0; iteration < b.N; iteration++ {
+		artifact, err := reader.Read(context.Background(), ref)
+		if err != nil {
+			b.Fatalf("read retained artifact: %v", err)
+		}
+		retained[iteration%len(retained)] = artifact
+	}
+	b.StopTimer()
+	for i, artifact := range retained {
+		if artifact != nil {
+			continue
+		}
+		artifact, err := reader.Read(context.Background(), ref)
+		if err != nil {
+			b.Fatalf("fill retained artifact batch: %v", err)
+		}
+		retained[i] = artifact
+	}
+	runtime.GC()
+	var retainedMemory runtime.MemStats
+	runtime.ReadMemStats(&retainedMemory)
+	b.ReportMetric(float64(int64(retainedMemory.HeapAlloc)-int64(setupMemory.HeapAlloc)), "retained-B")
+	runtime.KeepAlive(retained)
+	runtime.KeepAlive(reader)
+	runtime.KeepAlive(ref)
+}
+
+type artifactReadBenchmarkFile struct {
+	name string
+	path string
+	body []byte
+}
+
+func makeArtifactReadBenchmarkFiles(b *testing.B) []artifactReadBenchmarkFile {
+	b.Helper()
+	fixtures := []struct {
+		name string
+		size int
+	}{
+		{name: "small_4KiB", size: 4 << 10},
+		{name: "1MiB", size: 1 << 20},
+		{name: "large_4MiB", size: 4 << 20},
+	}
+	results := make([]artifactReadBenchmarkFile, 0, len(fixtures))
+	for _, fixture := range fixtures {
+		body := bytes.Repeat([]byte("x"), fixture.size)
+		path := filepath.Join(b.TempDir(), fixture.name+".txt")
+		if err := os.WriteFile(path, body, 0o600); err != nil {
+			b.Fatal(err)
+		}
+		mime.TypeByExtension(filepath.Ext(path))
+		results = append(results, artifactReadBenchmarkFile{
+			name: fixture.name,
+			path: path,
+			body: body,
+		})
+	}
+	return results
+}
+
+func checkArtifactFileRead(b *testing.B, reader Reader, ref domain.ArtifactRef, want []byte) {
+	b.Helper()
+	artifact, err := reader.Read(context.Background(), ref)
+	if err != nil {
+		b.Fatalf("check artifact read: %v", err)
+	}
+	if !bytes.Equal(artifact.Body, want) || artifact.Size != int64(len(want)) {
+		b.Fatalf("artifact size=%d body length=%d, want %d", artifact.Size, len(artifact.Body), len(want))
+	}
+	wantHash := fmt.Sprintf("%x", sha256.Sum256(want))
+	if artifact.Hash != wantHash {
+		b.Fatalf("artifact hash=%q, want %q", artifact.Hash, wantHash)
+	}
+}
+
+type sizeReportingArtifactFile struct {
+	artifactFile
+	reportedSize int64
+}
+
+func (file *sizeReportingArtifactFile) Stat() (os.FileInfo, error) {
+	info, err := file.artifactFile.Stat()
+	if err != nil {
+		return nil, err
+	}
+	return reportedArtifactFileInfo{FileInfo: info, size: file.reportedSize}, nil
+}
+
+type reportedArtifactFileInfo struct {
+	os.FileInfo
+	size int64
+}
+
+func (info reportedArtifactFileInfo) Size() int64 { return info.size }

internal/artifact/reader_test.go

@@ -3,7 +3,9 @@ package artifact
 import (
 	"bytes"
 	"context"
+	"crypto/sha256"
 	"errors"
+	"fmt"
 	"os"
 	"path/filepath"
 	"strings"
@@ -232,6 +234,64 @@ func TestFileReaderFailuresAndMetadata(t *testing.T) {
 	})
 }
 
+func TestFileReaderUsesOpenedSizeOnlyAsACapacityHint(t *testing.T) {
+	tests := []struct {
+		name         string
+		body         []byte
+		reportedSize int64
+	}{
+		{name: "overreported size", body: []byte("actual file content"), reportedSize: 128},
+		{name: "overreported size with empty content", body: []byte{}, reportedSize: 16 << 20},
+		{name: "underreported size", body: bytes.Repeat([]byte("x"), fileReadChunkSize+17), reportedSize: 1},
+		{name: "very large hint with small content", body: []byte("small actual content"), reportedSize: int64(^uint64(0) >> 1)},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			filePath := filepath.Join(t.TempDir(), "artifact.txt")
+			if err := os.WriteFile(filePath, tc.body, 0o600); err != nil {
+				t.Fatal(err)
+			}
+			reader := &fileReader{open: func(path string) (artifactFile, error) {
+				file, err := os.Open(path)
+				if err != nil {
+					return nil, err
+				}
+				info, err := file.Stat()
+				if err != nil {
+					file.Close()
+					return nil, err
+				}
+				return &reportedInfoFile{
+					artifactFile: file,
+					info:         reportedFileSizeInfo{FileInfo: info, size: tc.reportedSize},
+				}, nil
+			}}
+
+			artifact, err := reader.Read(context.Background(), domain.ArtifactRef{
+				Type: domain.ArtifactRefFile,
+				URI:  filePath,
+			})
+			if err != nil {
+				t.Fatalf("read artifact: %v", err)
+			}
+			if !bytes.Equal(artifact.Body, tc.body) {
+				t.Fatalf("artifact body length=%d, want %d", len(artifact.Body), len(tc.body))
+			}
+			if artifact.Size != int64(len(tc.body)) {
+				t.Fatalf("artifact size=%d, want %d", artifact.Size, len(tc.body))
+			}
+			if artifact.Name != filepath.Base(filePath) || artifact.URI != filePath || artifact.ContentType == "" {
+				t.Fatalf("unexpected artifact metadata: name=%q URI=%q content type=%q", artifact.Name, artifact.URI, artifact.ContentType)
+			}
+			wantHash := fmt.Sprintf("%x", sha256.Sum256(tc.body))
+			if artifact.Hash != wantHash {
+				t.Fatalf("artifact hash=%q, want %q", artifact.Hash, wantHash)
+			}
+		})
+	}
+}
+
 func TestFileReaderCancelsAfterReadProgress(t *testing.T) {
 	filePath := filepath.Join(t.TempDir(), "artifact.bin")
 	content := bytes.Repeat([]byte("x"), fileReadChunkSize*2)
@@ -268,6 +328,13 @@ func (f *reportedInfoFile) Stat() (os.FileInfo, error) {
 	return f.info, nil
 }
 
+type reportedFileSizeInfo struct {
+	os.FileInfo
+	size int64
+}
+
+func (info reportedFileSizeInfo) Size() int64 { return info.size }
+
 type cancelAfterProgressFile struct {
 	artifactFile
 	cancel context.CancelFunc

internal/backend/registry.go

@@ -7,13 +7,12 @@ import (
 	"fmt"
 
 	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
-	"gitea.maximumdirect.net/eric/promptkit/internal/jsonvalue"
 )
 
 const (
-	// OpenRouterID identifies the maintained OpenRouter backend.
+	// OpenRouterID is the conventional OpenRouter backend identifier.
 	OpenRouterID = "openrouter"
-	// RakestrawHomeID identifies the maintained Rakestrawhome backend.
+	// RakestrawHomeID is the conventional Rakestrawhome backend identifier.
 	RakestrawHomeID = "rakestrawhome"
 )
 
@@ -31,13 +30,12 @@ type Registry struct {
 func NewEffectiveRegistry(definitions map[string]domain.Backend) (*Registry, error) {
 	registry := &Registry{backends: make(map[string]domain.Backend, len(definitions))}
 	for id, definition := range definitions {
-		params, err := jsonvalue.CopyMap(definition.ExtraParams)
-		if err != nil {
-			return nil, fmt.Errorf("backend %q extra parameters: %w", id, err)
-		}
 		definition.ID = id
-		definition.ExtraParams = params
-		registry.backends[id] = definition
+		cloned, err := domain.CloneBackend(definition)
+		if err != nil {
+			return nil, fmt.Errorf("backend %q: %w", id, err)
+		}
+		registry.backends[id] = cloned
 	}
 	return registry, nil
 }
@@ -51,12 +49,11 @@ func (r *Registry) GetBackend(id string) (domain.Backend, error) {
 	if !ok {
 		return domain.Backend{}, fmt.Errorf("%w: %q", ErrBackendNotFound, id)
 	}
-	extraParams, err := jsonvalue.CopyMap(definition.ExtraParams)
+	cloned, err := domain.CloneBackend(definition)
 	if err != nil {
 		return domain.Backend{}, fmt.Errorf("copy backend %q: %w", id, err)
 	}
-	definition.ExtraParams = extraParams
-	return definition, nil
+	return cloned, nil
 }
 
 // CapacityPolicies returns a copy of the normalized policies for limited

internal/backend/registry_test.go

@@ -11,25 +11,61 @@ import (
 
 func TestEffectiveRegistryOwnsDefinitionsAndCapacityPolicies(t *testing.T) {
 	params := map[string]any{"nested": map[string]any{"enabled": true}}
+	defaultProfile := "catalog-profile"
+	reachabilityEndpoint := "https://probe.example/ready"
+	authenticationKind := "openrouter_key"
+	authenticationEndpoint := "https://probe.example/key"
+	smokeTests := &domain.BackendSmokeTestConfig{
+		DefaultProfile: &defaultProfile,
+		Reachability:   &domain.ReachabilityProbeConfig{Endpoint: &reachabilityEndpoint},
+		Authentication: &domain.AuthenticationProbeConfig{
+			Kind: &authenticationKind, Endpoint: &authenticationEndpoint,
+		},
+	}
 	registry, err := backend.NewEffectiveRegistry(map[string]domain.Backend{
 		" local.v1 ": {
 			Endpoint: "https://backend.example/v1", ExtraParams: params,
 			ConcurrencyLimit: 2, QueueCapacity: 3, QueueCapacitySet: true,
+			SmokeTests: smokeTests,
 		},
 	})
 	if err != nil {
 		t.Fatal(err)
 	}
 	params["nested"].(map[string]any)["enabled"] = false
+	defaultProfile = "mutated-profile"
+	reachabilityEndpoint = "https://mutated.example/ready"
+	authenticationKind = "none"
+	authenticationEndpoint = "https://mutated.example/key"
 	selected, err := registry.GetBackend(" local.v1 ")
 	if err != nil || selected.ID != " local.v1 " || selected.ExtraParams["nested"].(map[string]any)["enabled"] != true {
 		t.Fatalf("effective backend was not captured under its literal ID: %+v, %v", selected, err)
 	}
+	if selected.SmokeTests == nil || selected.SmokeTests.DefaultProfile == nil ||
+		*selected.SmokeTests.DefaultProfile != "catalog-profile" || selected.SmokeTests.Reachability == nil ||
+		selected.SmokeTests.Reachability.Endpoint == nil || *selected.SmokeTests.Reachability.Endpoint != "https://probe.example/ready" ||
+		selected.SmokeTests.Authentication == nil || selected.SmokeTests.Authentication.Kind == nil ||
+		*selected.SmokeTests.Authentication.Kind != "openrouter_key" || selected.SmokeTests.Authentication.Endpoint == nil ||
+		*selected.SmokeTests.Authentication.Endpoint != "https://probe.example/key" {
+		t.Fatalf("registry did not capture nested diagnostic metadata: %+v", selected.SmokeTests)
+	}
 	selected.ExtraParams["nested"].(map[string]any)["enabled"] = false
+	*selected.SmokeTests.DefaultProfile = "mutated-return"
+	*selected.SmokeTests.Reachability.Endpoint = "https://mutated-return.example/ready"
+	*selected.SmokeTests.Authentication.Kind = "none"
+	*selected.SmokeTests.Authentication.Endpoint = "https://mutated-return.example/key"
 	again, err := registry.GetBackend(" local.v1 ")
 	if err != nil || again.ExtraParams["nested"].(map[string]any)["enabled"] != true {
 		t.Fatalf("lookup exposed registry values: %+v, %v", again, err)
 	}
+	if again.SmokeTests == nil || again.SmokeTests.DefaultProfile == nil ||
+		*again.SmokeTests.DefaultProfile != "catalog-profile" || again.SmokeTests.Reachability == nil ||
+		again.SmokeTests.Reachability.Endpoint == nil || *again.SmokeTests.Reachability.Endpoint != "https://probe.example/ready" ||
+		again.SmokeTests.Authentication == nil || again.SmokeTests.Authentication.Kind == nil ||
+		*again.SmokeTests.Authentication.Kind != "openrouter_key" || again.SmokeTests.Authentication.Endpoint == nil ||
+		*again.SmokeTests.Authentication.Endpoint != "https://probe.example/key" {
+		t.Fatalf("lookup exposed nested diagnostic metadata: %+v", again.SmokeTests)
+	}
 	policies := registry.CapacityPolicies()
 	if !reflect.DeepEqual(policies, map[string]domain.BackendCapacityPolicy{
 		" local.v1 ": {ConcurrencyLimit: 2, QueueCapacity: 3},

internal/catalog/catalog.go

@@ -1,52 +0,0 @@
-// Package catalog selects the maintained configuration assets supplied with
-// PromptKit. ConfigKit owns their composition and effective validation.
-package catalog
-
-import (
-	"context"
-	"fmt"
-	"io/fs"
-
-	"gitea.maximumdirect.net/eric/ConfigKit"
-	openrouter "gitea.maximumdirect.net/eric/promptkit-backend-openrouter/v3"
-	rakestrawhome "gitea.maximumdirect.net/eric/promptkit-backend-rakestrawhome/v3"
-	"gitea.maximumdirect.net/eric/promptkit/internal/backend"
-	"gitea.maximumdirect.net/eric/promptkit/internal/filecatalog"
-)
-
-// Underlays selects external catalogs followed by PromptKit-owned profiles.
-// Neither group is interpreted before the final effective configuration loads.
-func Underlays() ([]configkit.Underlay, error) {
-	openrouterInputs, err := assetInputs("OpenRouter catalog", openrouter.FS(), openrouter.Root)
-	if err != nil {
-		return nil, err
-	}
-	rakestrawhomeInputs, err := assetInputs("Rakestrawhome catalog", rakestrawhome.FS(), rakestrawhome.Root)
-	if err != nil {
-		return nil, err
-	}
-	catalogInputs := append(openrouterInputs, rakestrawhomeInputs...)
-	owned := configkit.Input{Source: configkit.Mapping("PromptKit-owned profiles", map[string]any{
-		"profiles": map[string]any{
-			"promptkit-openrouter-standard": map[string]any{"extends": "gemini-flash-latest"},
-			"promptkit-openrouter-auto":     map[string]any{"backend": backend.OpenRouterID, "model": "openrouter/auto"},
-		},
-	})}
-	return []configkit.Underlay{{Inputs: catalogInputs}, {Inputs: []configkit.Input{owned}}}, nil
-}
-
-func assetInputs(label string, filesystem fs.FS, root string) ([]configkit.Input, error) {
-	files, err := filecatalog.FindFSYAMLFiles(context.Background(), filesystem, root)
-	if err != nil {
-		return nil, fmt.Errorf("discover %s configuration: %w", label, err)
-	}
-	namespace := configkit.NewFilesystem(label, filesystem)
-	inputs := make([]configkit.Input, 0, len(files))
-	for _, name := range files {
-		inputs = append(inputs, configkit.Input{
-			Source:     namespace.File(name),
-			Filesystem: &configkit.FilesystemContext{FS: &namespace, Root: root},
-		})
-	}
-	return inputs, nil
-}

internal/catalog/catalog_test.go

@@ -1,68 +0,0 @@
-package catalog
-
-import (
-	"context"
-	"errors"
-	"testing"
-
-	"gitea.maximumdirect.net/eric/ConfigKit"
-	"gitea.maximumdirect.net/eric/promptkit/internal/configuration"
-)
-
-func TestPublishedCatalogsResolveThroughEffectiveConfiguration(t *testing.T) {
-	underlays, err := Underlays()
-	if err != nil {
-		t.Fatal(err)
-	}
-	state, err := configuration.Load(configkit.Input{Source: configkit.NoSource()}, underlays)
-	if err != nil {
-		t.Fatal(err)
-	}
-	openrouter, err := state.GetBackend("openrouter")
-	if err != nil || openrouter.Endpoint != "https://openrouter.ai/api/v1" || openrouter.ConcurrencyLimit != 16 || openrouter.QueueCapacity != 1024 {
-		t.Fatalf("OpenRouter backend: %+v, %v", openrouter, err)
-	}
-	rakestrawhome, err := state.GetBackend("rakestrawhome")
-	if err != nil || rakestrawhome.Endpoint != "https://inference.ai.rakestrawhome.com/v1" || rakestrawhome.ConcurrencyLimit != 4 {
-		t.Fatalf("Rakestrawhome backend: %+v, %v", rakestrawhome, err)
-	}
-	for id, want := range map[string]string{
-		"promptkit-openrouter-standard": "~google/gemini-flash-latest",
-		"promptkit-openrouter-auto":     "openrouter/auto",
-		"rakestrawhome-gemma-4-31b":     "google/gemma-4-31b-it",
-	} {
-		profile, err := state.GetProfile(context.Background(), id)
-		if err != nil || profile.ResolvedTarget.Model != want {
-			t.Fatalf("profile %s: %+v, %v", id, profile, err)
-		}
-	}
-}
-
-func TestConsumerOverlayReplacesCatalogDefaultsBeforeValidation(t *testing.T) {
-	underlays, err := Underlays()
-	if err != nil {
-		t.Fatal(err)
-	}
-	underlays = append(underlays, configkit.Underlay{Inputs: []configkit.Input{{Source: configkit.Mapping("operator", map[string]any{
-		"backends": map[string]any{"openrouter": map[string]any{"endpoint": "invalid lower value"}},
-	})}}})
-	main := configkit.Input{Source: configkit.Mapping("application", map[string]any{
-		"backends": map[string]any{"openrouter": map[string]any{"endpoint": "https://alternate.example/v1"}},
-		"profiles": map[string]any{"gemini-flash-latest": map[string]any{"model": "consumer-model"}},
-	})}
-	state, err := configuration.Load(main, underlays)
-	if err != nil {
-		t.Fatalf("replaced lower-layer value failed final validation: %v", err)
-	}
-	profile, err := state.GetProfile(context.Background(), "promptkit-openrouter-standard")
-	if err != nil || profile.ResolvedTarget.Model != "consumer-model" || profile.ResolvedTarget.Endpoint != "https://alternate.example/v1" {
-		t.Fatalf("maintained profile did not observe final configuration: %+v, %v", profile, err)
-	}
-	_, err = configuration.Load(configkit.Input{Source: configkit.Mapping("invalid final", map[string]any{
-		"backends": map[string]any{"openrouter": map[string]any{"endpoint": "invalid final value"}},
-	})}, underlays[:2])
-	var loadError *configkit.LoadError
-	if !errors.As(err, &loadError) {
-		t.Fatalf("invalid final backend did not produce a ConfigKit load error: %v", err)
-	}
-}

internal/configuration/benchmark_test.go

@@ -13,9 +13,12 @@ import (
 const benchmarkDefinitionCount = 128
 
 var (
-	constructionResult *loaded
-	selectedPrompt     *domain.PromptDefinition
-	selectedProfile    *domain.ExecutionProfile
+	constructionResult       *loaded
+	selectedPrompt           *domain.PromptDefinition
+	selectedPromptHash       string
+	selectedPromptInspection *domain.PromptInspection
+	selectedProfile          *domain.ExecutionProfile
+	selectedProfileIdentity  string
 )
 
 type configurationShape struct {
@@ -28,6 +31,7 @@ type configurationShape struct {
 
 func benchmarkPrompt(profileID string) map[string]any {
 	return map[string]any{
+		"version":         "1",
 		"default_profile": profileID,
 		"messages":        []any{map[string]any{"role": "user", "content": "Hello {{.name}}"}},
 		"output":          map[string]any{"format": "text", "validation_mode": "none"},
@@ -41,7 +45,7 @@ func independentDefinitions(count int) configurationShape {
 		profileID := fmt.Sprintf("profile-%03d", index)
 		promptID := fmt.Sprintf("prompt-%03d", index)
 		profiles[profileID] = map[string]any{"endpoint": "https://example.test/v1", "model": profileID}
-		prompts[promptID] = map[string]any{"1": benchmarkPrompt(profileID)}
+		prompts[promptID] = benchmarkPrompt(profileID)
 	}
 	return configurationShape{
 		main:             configkit.Input{Source: configkit.Mapping("independent definitions", map[string]any{"profiles": profiles, "prompts": prompts})},
@@ -60,7 +64,7 @@ func fileBackedDefinitions(count int) configurationShape {
 		profiles[profileID] = map[string]any{"endpoint": "https://example.test/v1", "model": profileID}
 		prompt := benchmarkPrompt(profileID)
 		prompt["messages"] = []any{map[string]any{"role": "user", "content_file": "body.md"}}
-		prompts[promptID] = map[string]any{"1": prompt}
+		prompts[promptID] = prompt
 	}
 	namespace := configkit.NewFilesystem("benchmark content", fstest.MapFS{
 		"assets/body.md": &fstest.MapFile{Data: []byte("Hello {{.name}}")},
@@ -86,7 +90,7 @@ func sharedBaseDefinitions(count int) configurationShape {
 	return configurationShape{
 		main: configkit.Input{Source: configkit.Mapping("inherited definitions", map[string]any{
 			"profiles": profiles,
-			"prompts":  map[string]any{"shared": map[string]any{"1": benchmarkPrompt(fmt.Sprintf("child-%03d", count-1))}},
+			"prompts":  map[string]any{"shared": benchmarkPrompt(fmt.Sprintf("child-%03d", count-1))},
 		})},
 		inputEntries:     count + 2,
 		effectiveEntries: count + 2,
@@ -114,7 +118,7 @@ func layeredDefinitions(count int) configurationShape {
 		},
 		main: configkit.Input{Source: configkit.Mapping("main", map[string]any{
 			"profiles": final,
-			"prompts":  map[string]any{"layered": map[string]any{"1": benchmarkPrompt(fmt.Sprintf("profile-%03d", count-1))}},
+			"prompts":  map[string]any{"layered": benchmarkPrompt(fmt.Sprintf("profile-%03d", count-1))},
 		})},
 		inputEntries:     count*4 + 1,
 		effectiveEntries: count + 1,
@@ -122,6 +126,40 @@ func layeredDefinitions(count int) configurationShape {
 	}
 }
 
+func BenchmarkCollectionFileBackedConstruction(b *testing.B) {
+	for _, count := range []int{4, 16, 64} {
+		b.Run(fmt.Sprintf("collections_%d", count), func(b *testing.B) {
+			collections := make(map[string]any, count)
+			for index := range count {
+				collections[fmt.Sprintf("collection-%03d", index)] = map[string]any{
+					"prompts": map[string]any{
+						"example": map[string]any{
+							"messages": []any{map[string]any{"role": "user", "content_file": "body.md"}},
+							"output":   map[string]any{"format": "text", "validation_mode": "none"},
+						},
+					},
+				}
+			}
+			namespace := configkit.NewFilesystem("collection benchmark", fstest.MapFS{
+				"body.md": {Data: []byte("Hello")},
+			})
+			main := configkit.Input{
+				Source:     configkit.Mapping("collections", map[string]any{"collections": collections}),
+				Filesystem: &configkit.FilesystemContext{FS: &namespace, Root: ".", BaseDir: "."},
+			}
+			b.ReportAllocs()
+			for b.Loop() {
+				result, err := load(main, nil)
+				if err != nil {
+					b.Fatal(err)
+				}
+				constructionResult = result
+			}
+			b.ReportMetric(float64(count), "collections/op")
+		})
+	}
+}
+
 func BenchmarkConfigurationConstruction(b *testing.B) {
 	for _, scenario := range []struct {
 		name  string
@@ -157,7 +195,7 @@ func BenchmarkConfigurationSelection(b *testing.B) {
 	b.Run("prompt", func(b *testing.B) {
 		b.ReportAllocs()
 		for b.Loop() {
-			definition, _, err := result.prompt("prompt-127", "1")
+			definition, _, err := result.prompt("prompt-127")
 			if err != nil {
 				b.Fatal(err)
 			}
@@ -177,3 +215,116 @@ func BenchmarkConfigurationSelection(b *testing.B) {
 		b.ReportMetric(float64(shape.effectiveEntries), "effective-entries/op")
 	})
 }
+
+func inspectionExtraParams(entries int) map[string]any {
+	providers := make(map[string]any, entries)
+	for index := range entries {
+		providers[fmt.Sprintf("provider-%03d", index)] = map[string]any{
+			"enabled": true,
+			"labels":  []any{fmt.Sprintf("tier-%d", index%4), fmt.Sprintf("region-%d", index%3)},
+			"limits":  map[string]any{"burst": index + 1, "period": "minute"},
+			"routes":  []any{map[string]any{"weight": index + 1, "fallback": true}},
+		}
+	}
+	return map[string]any{"provider_options": providers}
+}
+
+func inspectionDefinitions(extraParams map[string]any) configurationShape {
+	profiles := map[string]any{
+		"small": map[string]any{"model": "inspection-model", "extra_params": extraParams},
+	}
+	prompt := benchmarkPrompt("small")
+	prompt["inputs"] = []any{map[string]any{"name": "transcript", "required": true}}
+	prompts := map[string]any{
+		"inspection": prompt,
+	}
+	return configurationShape{
+		main: configkit.Input{Source: configkit.Mapping("inspection definitions", map[string]any{
+			"profiles": profiles,
+			"prompts":  prompts,
+		})},
+		inputEntries: 2, effectiveEntries: 2, tiers: 1,
+	}
+}
+
+func BenchmarkInspectionSelection(b *testing.B) {
+	for _, scenario := range []struct {
+		name    string
+		entries int
+	}{
+		{name: "small_extra", entries: 2},
+		{name: "nested_extra", entries: 64},
+	} {
+		shape := inspectionDefinitions(inspectionExtraParams(scenario.entries))
+		result, err := load(shape.main, nil)
+		if err != nil {
+			b.Fatal(err)
+		}
+		ctx := context.Background()
+		definition, hash, err := result.GetPromptSnapshot(ctx, "inspection")
+		if err != nil || definition.ID != "inspection" || definition.Version == nil || *definition.Version != "1" || hash == "" ||
+			len(definition.Inputs) != 1 || definition.Inputs[0].Name != "transcript" || !definition.Inputs[0].Required {
+			b.Fatalf("prompt lookup fixture is invalid: definition=%+v hash=%q err=%v", definition, hash, err)
+		}
+		profile, err := result.GetProfile(ctx, "small")
+		if err != nil || profile.ID != "small" || profile.ResolvedTarget.Model != "inspection-model" ||
+			len(profile.ResolvedTarget.ExtraParams["provider_options"].(map[string]any)) != scenario.entries {
+			b.Fatalf("profile lookup fixture is invalid: profile=%+v err=%v", profile, err)
+		}
+		inspection, err := result.GetPromptInspection(ctx, "inspection")
+		if err != nil || inspection.PromptID != "inspection" || inspection.PromptVersion == nil || *inspection.PromptVersion != "1" ||
+			len(inspection.Inputs) != 1 || inspection.Inputs[0].Name != "transcript" {
+			b.Fatalf("prompt inspection fixture is invalid: inspection=%+v err=%v", inspection, err)
+		}
+		identity, err := result.GetProfileIdentity(ctx, "small")
+		if err != nil || identity != "small" {
+			b.Fatalf("profile identity fixture is invalid: identity=%q err=%v", identity, err)
+		}
+
+		b.Run("prompt/"+scenario.name, func(b *testing.B) {
+			b.ReportAllocs()
+			for b.Loop() {
+				definition, hash, err := result.GetPromptSnapshot(ctx, "inspection")
+				if err != nil {
+					b.Fatal(err)
+				}
+				selectedPrompt = definition
+				selectedPromptHash = hash
+			}
+			b.ReportMetric(float64(scenario.entries), "extra-entries/op")
+		})
+		b.Run("prompt_inspection/"+scenario.name, func(b *testing.B) {
+			b.ReportAllocs()
+			for b.Loop() {
+				inspection, err := result.GetPromptInspection(ctx, "inspection")
+				if err != nil {
+					b.Fatal(err)
+				}
+				selectedPromptInspection = inspection
+			}
+			b.ReportMetric(float64(scenario.entries), "extra-entries/op")
+		})
+		b.Run("profile/"+scenario.name, func(b *testing.B) {
+			b.ReportAllocs()
+			for b.Loop() {
+				profile, err := result.GetProfile(ctx, "small")
+				if err != nil {
+					b.Fatal(err)
+				}
+				selectedProfile = profile
+			}
+			b.ReportMetric(float64(scenario.entries), "extra-entries/op")
+		})
+		b.Run("profile_identity/"+scenario.name, func(b *testing.B) {
+			b.ReportAllocs()
+			for b.Loop() {
+				identity, err := result.GetProfileIdentity(ctx, "small")
+				if err != nil {
+					b.Fatal(err)
+				}
+				selectedProfileIdentity = identity
+			}
+			b.ReportMetric(float64(scenario.entries), "extra-entries/op")
+		})
+	}
+}

internal/configuration/inspection.go

@@ -16,6 +16,15 @@ type Inspection interface {
 	Explain(configkit.Path) (configkit.Explanation, bool)
 	WriteEffective(io.Writer) error
 	WriteExplanation(io.Writer, configkit.Path) error
+	capturedResult() *configkit.Result[document]
+}
+
+type inspectionResult struct {
+	*configkit.Result[document]
+}
+
+func (inspection inspectionResult) capturedResult() *configkit.Result[document] {
+	return inspection.Result
 }
 
 // Inspection returns only the retained result's inspection operations.
@@ -23,7 +32,19 @@ func (state *loaded) Inspection() Inspection {
 	if state == nil {
 		return nil
 	}
-	return state.result
+	return inspectionResult{Result: state.result}
+}
+
+// Diff compares two captured ConfigKit results without reconstructing them.
+func Diff(left, right Inspection) ([]configkit.Difference, error) {
+	var leftResult, rightResult *configkit.Result[document]
+	if left != nil {
+		leftResult = left.capturedResult()
+	}
+	if right != nil {
+		rightResult = right.capturedResult()
+	}
+	return configkit.Diff(leftResult, rightResult)
 }
 
 func secretProviderPath(path configkit.Path) bool {
@@ -32,7 +53,7 @@ func secretProviderPath(path configkit.Path) bool {
 		return false
 	}
 	parts := strings.Split(strings.TrimPrefix(pointer, "/"), "/")
-	if len(parts) < 4 || (parts[0] != "backends" && parts[0] != "profiles") || parts[2] != "extra_params" {
+	if !providerExtraParamsPath(parts) {
 		return false
 	}
 	key := strings.ToLower(strings.ReplaceAll(strings.ReplaceAll(parts[len(parts)-1], "~1", "/"), "~0", "~"))
@@ -43,3 +64,13 @@ func secretProviderPath(path configkit.Path) bool {
 		return false
 	}
 }
+
+func providerExtraParamsPath(parts []string) bool {
+	if len(parts) >= 4 && parts[1] != "" &&
+		(parts[0] == "backends" || parts[0] == "profiles") && parts[2] == "extra_params" {
+		return true
+	}
+	return len(parts) >= 6 && parts[0] == "collections" && parts[1] != "" &&
+		(parts[2] == "backends" || parts[2] == "profiles") &&
+		parts[3] != "" && parts[4] == "extra_params"
+}

internal/configuration/inspection_test.go

@@ -0,0 +1,32 @@
+package configuration
+
+import (
+	"testing"
+
+	"gitea.maximumdirect.net/eric/ConfigKit"
+)
+
+func TestSecretProviderPathRecognizesResourceExtraParams(t *testing.T) {
+	tests := []struct {
+		name string
+		path configkit.Path
+		want bool
+	}{
+		{name: "backend nested secret", path: configkit.Keys("backends", "provider", "extra_params", "nested", "Token"), want: true},
+		{name: "profile nested secret", path: configkit.Keys("profiles", "assistant", "extra_params", "authorization"), want: true},
+		{name: "collection backend nested secret", path: configkit.Keys("collections", "provider", "backends", "default", "extra_params", "nested", "Token"), want: true},
+		{name: "collection profile secret", path: configkit.Keys("collections", "assistant", "profiles", "model", "extra_params", "authorization"), want: true},
+		{name: "unrelated nested mapping", path: configkit.Keys("application", "backends", "provider", "extra_params", "token"), want: false},
+		{name: "extra params outside resource map", path: configkit.Keys("backends", "provider", "options", "extra_params", "token"), want: false},
+		{name: "collection extra params outside resource map", path: configkit.Keys("collections", "provider", "settings", "backends", "default", "extra_params", "token"), want: false},
+		{name: "missing resource key", path: configkit.Keys("backends", "", "extra_params", "token"), want: false},
+		{name: "ordinary provider value", path: configkit.Keys("profiles", "assistant", "extra_params", "provider", "mode"), want: false},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			if got := secretProviderPath(test.path); got != test.want {
+				t.Fatalf("secretProviderPath(%q) = %t, want %t", test.path, got, test.want)
+			}
+		})
+	}
+}

internal/configuration/listing.go

@@ -0,0 +1,87 @@
+package configuration
+
+import (
+	"context"
+
+	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
+)
+
+// CollectionIdentity is the captured metadata for one final collection entry.
+type CollectionIdentity struct {
+	Namespace      string
+	ReleaseVersion *string
+}
+
+func (state *loaded) ListProfiles(ctx context.Context) ([]string, error) {
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	profiles := append([]string(nil), state.profileIDs...)
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	return profiles, nil
+}
+
+func (state *loaded) ListBackends(ctx context.Context) ([]string, error) {
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	backends := append([]string(nil), state.backendIDs...)
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	return backends, nil
+}
+
+func (state *loaded) ListNamespaces(ctx context.Context, kinds []string) ([]string, error) {
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	selected := kinds
+	if len(selected) == 0 {
+		selected = []string{"backend", "profile", "prompt"}
+	}
+	set := make(map[string]struct{})
+	for _, kind := range selected {
+		for _, namespace := range state.namespaces[kind] {
+			set[namespace] = struct{}{}
+		}
+	}
+	namespaces := sortedKeys(set)
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	return namespaces, nil
+}
+
+func (state *loaded) ListCollections(ctx context.Context) ([]CollectionIdentity, error) {
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	collections := make([]CollectionIdentity, len(state.collections))
+	for index, collection := range state.collections {
+		collections[index] = CollectionIdentity{
+			Namespace:      collection.Namespace,
+			ReleaseVersion: stringPointerValue(collection.ReleaseVersion),
+		}
+	}
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	return collections, nil
+}
+
+func (state *loaded) ListPrompts(ctx context.Context) ([]domain.PromptIdentity, error) {
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	prompts := append([]domain.PromptIdentity(nil), state.promptIDs...)
+	for index := range prompts {
+		prompts[index].Version = stringPointerValue(prompts[index].Version)
+	}
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	return prompts, nil
+}

internal/configuration/listing_test.go

@@ -0,0 +1,160 @@
+package configuration
+
+import (
+	"context"
+	"errors"
+	"reflect"
+	"testing"
+
+	"gitea.maximumdirect.net/eric/ConfigKit"
+	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
+)
+
+func TestLoadedListsSortedEffectiveIdentities(t *testing.T) {
+	state, err := Load(mapping("identities", map[string]any{
+		"backends": map[string]any{
+			"local": map[string]any{"endpoint": "http://localhost:8080/v1"},
+		},
+		"collections": map[string]any{
+			"z":       map[string]any{"profiles": map[string]any{"profile": map[string]any{"backend": "local", "model": "z-model"}}, "prompts": map[string]any{"prompt": listingPromptDefinition()}},
+			"partial": map[string]any{"profiles": map[string]any{"profile": map[string]any{"backend": "local"}}},
+			"a":       map[string]any{"profiles": map[string]any{"profile": map[string]any{"backend": "local", "model": "a-model"}}, "prompts": map[string]any{"prompt": listingPromptDefinition()}},
+			" z":      map[string]any{"profiles": map[string]any{"profile ": map[string]any{"backend": "local", "model": "spaced-model"}}, "prompts": map[string]any{"prompt ": listingPromptDefinition()}},
+		},
+	}), nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	backends, err := state.ListBackends(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	wantBackends := []string{"local"}
+	if !reflect.DeepEqual(backends, wantBackends) {
+		t.Fatalf("backend IDs = %#v, want %#v", backends, wantBackends)
+	}
+
+	profiles, err := state.ListProfiles(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	wantProfiles := []string{" z/profile ", "a/profile", "partial/profile", "z/profile"}
+	if !reflect.DeepEqual(profiles, wantProfiles) {
+		t.Fatalf("profile IDs = %#v, want %#v", profiles, wantProfiles)
+	}
+
+	prompts, err := state.ListPrompts(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	wantPrompts := []domain.PromptIdentity{
+		{ID: " z/prompt ", Version: stringPointer("v1")},
+		{ID: "a/prompt", Version: stringPointer("v1")},
+		{ID: "z/prompt", Version: stringPointer("v1")},
+	}
+	if !reflect.DeepEqual(prompts, wantPrompts) {
+		t.Fatalf("prompt identities = %#v, want %#v", prompts, wantPrompts)
+	}
+}
+
+func TestLoadedListsAreIndependent(t *testing.T) {
+	state, err := Load(mapping("identities", map[string]any{
+		"backends": map[string]any{"backend": map[string]any{"endpoint": "https://example.test/v1"}},
+		"profiles": map[string]any{"profile": map[string]any{}},
+		"prompts":  map[string]any{"example": listingPromptDefinition()},
+	}), nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	profiles, err := state.ListProfiles(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	profiles = append(profiles, "caller profile")
+	profiles[0] = "changed profile"
+	backends, err := state.ListBackends(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	backends[0] = "changed backend"
+
+	prompts, err := state.ListPrompts(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	prompts[0].ID = "changed prompt"
+	*prompts[0].Version = "changed version"
+
+	profiles, err = state.ListProfiles(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !reflect.DeepEqual(profiles, []string{"profile"}) {
+		t.Fatalf("caller mutation changed profile inventory: %#v", profiles)
+	}
+	backends, err = state.ListBackends(context.Background())
+	if err != nil || !reflect.DeepEqual(backends, []string{"backend"}) {
+		t.Fatalf("caller mutation changed backend inventory: %#v, %v", backends, err)
+	}
+	prompts, err = state.ListPrompts(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	wantPrompts := []domain.PromptIdentity{{ID: "example", Version: stringPointer("v1")}}
+	if !reflect.DeepEqual(prompts, wantPrompts) {
+		t.Fatalf("caller mutation changed prompt inventory: %#v", prompts)
+	}
+}
+
+func TestLoadedListsEmptyInventory(t *testing.T) {
+	state, err := Load(configkit.Input{Source: configkit.NoSource()}, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	profiles, err := state.ListProfiles(context.Background())
+	if err != nil || len(profiles) != 0 {
+		t.Fatalf("empty profile listing = %#v, %v", profiles, err)
+	}
+	backends, err := state.ListBackends(context.Background())
+	if err != nil || len(backends) != 0 {
+		t.Fatalf("empty backend listing = %#v, %v", backends, err)
+	}
+	prompts, err := state.ListPrompts(context.Background())
+	if err != nil || len(prompts) != 0 {
+		t.Fatalf("empty prompt listing = %#v, %v", prompts, err)
+	}
+}
+
+func TestLoadedListsHonorCanceledContext(t *testing.T) {
+	state, err := Load(mapping("identities", map[string]any{
+		"profiles": map[string]any{"partial": map[string]any{}},
+		"prompts":  map[string]any{"example": listingPromptDefinition()},
+	}), nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	profiles, err := state.ListProfiles(ctx)
+	if !errors.Is(err, context.Canceled) || len(profiles) != 0 {
+		t.Fatalf("canceled profile listing = %#v, %v", profiles, err)
+	}
+	backends, err := state.ListBackends(ctx)
+	if !errors.Is(err, context.Canceled) || len(backends) != 0 {
+		t.Fatalf("canceled backend listing = %#v, %v", backends, err)
+	}
+	prompts, err := state.ListPrompts(ctx)
+	if !errors.Is(err, context.Canceled) || len(prompts) != 0 {
+		t.Fatalf("canceled prompt listing = %#v, %v", prompts, err)
+	}
+}
+
+func listingPromptDefinition() map[string]any {
+	return map[string]any{
+		"version":  "v1",
+		"messages": []any{map[string]any{"role": "user", "content": "Hello."}},
+		"output":   map[string]any{"format": "text", "validation_mode": "basic"},
+	}
+}

internal/configuration/load.go

@@ -4,6 +4,7 @@ package configuration
 
 import (
 	"fmt"
+	"net/http"
 	"regexp"
 	"sort"
 	"strings"
@@ -16,17 +17,42 @@ import (
 )
 
 type document struct {
-	Backends map[string]backendConfig           `yaml:"backends"`
-	Profiles map[string]profileConfig           `yaml:"profiles"`
-	Prompts  map[string]map[string]promptConfig `yaml:"prompts"`
+	Version     *string                     `yaml:"version"`
+	Backends    map[string]backendConfig    `yaml:"backends"`
+	Profiles    map[string]profileConfig    `yaml:"profiles"`
+	Prompts     map[string]promptConfig     `yaml:"prompts"`
+	Collections map[string]collectionConfig `yaml:"collections"`
+}
+
+type collectionConfig struct {
+	ReleaseVersion *string                  `yaml:"release_version"`
+	Backends       map[string]backendConfig `yaml:"backends"`
+	Profiles       map[string]profileConfig `yaml:"profiles"`
+	Prompts        map[string]promptConfig  `yaml:"prompts"`
 }
 
 type backendConfig struct {
-	Endpoint         *string        `yaml:"endpoint"`
-	APIKeyEnv        *string        `yaml:"api_key_env"`
-	ConcurrencyLimit *int           `yaml:"concurrency_limit"`
-	QueueCapacity    *int           `yaml:"queue_capacity"`
-	ExtraParams      map[string]any `yaml:"extra_params"`
+	Endpoint         *string                 `yaml:"endpoint"`
+	APIKeyEnv        *string                 `yaml:"api_key_env"`
+	ConcurrencyLimit *int                    `yaml:"concurrency_limit"`
+	QueueCapacity    *int                    `yaml:"queue_capacity"`
+	ExtraParams      map[string]any          `yaml:"extra_params"`
+	SmokeTests       *backendSmokeTestConfig `yaml:"smoke_tests"`
+}
+
+type backendSmokeTestConfig struct {
+	DefaultProfile *string                    `yaml:"default_profile"`
+	Reachability   *reachabilityProbeConfig   `yaml:"reachability"`
+	Authentication *authenticationProbeConfig `yaml:"authentication"`
+}
+
+type reachabilityProbeConfig struct {
+	Endpoint *string `yaml:"endpoint"`
+}
+
+type authenticationProbeConfig struct {
+	Kind     *string `yaml:"kind"`
+	Endpoint *string `yaml:"endpoint"`
 }
 
 type profileConfig struct {
@@ -45,6 +71,7 @@ type profileConfig struct {
 }
 
 type promptConfig struct {
+	Version        *string               `yaml:"version"`
 	DefaultProfile *string               `yaml:"default_profile"`
 	Description    *string               `yaml:"description"`
 	SessionID      *string               `yaml:"session_id"`
@@ -54,10 +81,10 @@ type promptConfig struct {
 }
 
 type promptInputConfig struct {
-	Name        string `yaml:"name"`
-	Required    bool   `yaml:"required"`
-	ContentType string `yaml:"content_type"`
-	Description string `yaml:"description"`
+	Name        string  `yaml:"name"`
+	Required    bool    `yaml:"required"`
+	ContentType *string `yaml:"content_type"`
+	Description *string `yaml:"description"`
 }
 
 type promptMessageConfig struct {
@@ -93,15 +120,98 @@ type loaded struct {
 	result          *configkit.Result[document]
 	backends        map[string]map[string]fieldState
 	profiles        map[string]map[string]fieldState
-	prompts         map[string]map[string]*promptEntry
-	ambiguous       map[string]bool
+	promptMetadata  map[string][]promptInputPresence
+	prompts         map[string]*promptEntry
 	registry        *backend.Registry
 	indexedProfiles map[string]domain.ExecutionProfile
+	backendIDs      []string
+	profileIDs      []string
+	promptIDs       []domain.PromptIdentity
+	namespaces      map[string][]string
+	collections     []CollectionIdentity
+}
+
+type resourceBases struct {
+	backends configkit.Path
+	profiles configkit.Path
+	prompts  configkit.Path
+}
+
+type resourceSet struct {
+	isCollection bool
+	namespace    string
+	bases        resourceBases
+	backends     map[string]backendConfig
+	profiles     map[string]profileConfig
+	prompts      map[string]promptConfig
+}
+
+func rootResourceBases() resourceBases {
+	return resourceBases{
+		backends: configkit.Keys("backends"),
+		profiles: configkit.Keys("profiles"),
+		prompts:  configkit.Keys("prompts"),
+	}
+}
+
+func resourceSets(config *document) []resourceSet {
+	sets := make([]resourceSet, 0, len(config.Collections)+1)
+	sets = append(sets, resourceSet{
+		bases: rootResourceBases(), backends: config.Backends, profiles: config.Profiles, prompts: config.Prompts,
+	})
+	for _, namespace := range sortedKeys(config.Collections) {
+		collection := config.Collections[namespace]
+		base := configkit.Keys("collections", namespace)
+		sets = append(sets, resourceSet{
+			isCollection: true,
+			namespace:    namespace,
+			bases: resourceBases{
+				backends: base.Key("backends"),
+				profiles: base.Key("profiles"),
+				prompts:  base.Key("prompts"),
+			},
+			backends: collection.Backends,
+			profiles: collection.Profiles,
+			prompts:  collection.Prompts,
+		})
+	}
+	return sets
+}
+
+func indexedResourceID(namespace, localKey string) string {
+	qualified, valid := domain.QualifyLocalResourceID(namespace, localKey)
+	if valid {
+		return qualified
+	}
+	if namespace == "" {
+		return localKey
+	}
+	return namespace + "/" + localKey
+}
+
+func indexedBackends(config *document) map[string]backendConfig {
+	backends := make(map[string]backendConfig)
+	for _, resources := range resourceSets(config) {
+		for localKey, definition := range resources.backends {
+			backends[indexedResourceID(resources.namespace, localKey)] = definition
+		}
+	}
+	return backends
+}
+
+func indexedProfiles(config *document) map[string]profileConfig {
+	profiles := make(map[string]profileConfig)
+	for _, resources := range resourceSets(config) {
+		for localKey, definition := range resources.profiles {
+			profiles[indexedResourceID(resources.namespace, localKey)] = definition
+		}
+	}
+	return profiles
 }
 
 var envName = regexp.MustCompile(`^[A-Za-z_][A-Za-z0-9_]*$`)
 
-var backendFields = []string{"endpoint", "api_key_env", "concurrency_limit", "queue_capacity", "extra_params"}
+var backendFields = []string{"endpoint", "api_key_env", "concurrency_limit", "queue_capacity", "extra_params", "smoke_tests"}
 var profileFields = []string{"backend", "endpoint", "model", "temperature", "top_p", "max_tokens", "timeout_seconds", "service_tier", "reasoning_effort", "api_key_env", "api_key_required", "extra_params"}
 
 // Load captures one immutable effective configuration for internal consumers.
@@ -112,22 +222,33 @@ func Load(main configkit.Input, underlays []configkit.Underlay) (*loaded, error)
 // load performs one ConfigKit lifecycle over the selected source tiers.
 func load(main configkit.Input, underlays []configkit.Underlay) (*loaded, error) {
 	state := &loaded{
-		backends: make(map[string]map[string]fieldState),
-		profiles: make(map[string]map[string]fieldState),
+		backends:       make(map[string]map[string]fieldState),
+		profiles:       make(map[string]map[string]fieldState),
+		promptMetadata: make(map[string][]promptInputPresence),
 	}
 	result, err := configkit.LoadLayered(main, configkit.LayeredOptions[document]{
-		Underlays: underlays,
+		Underlays:         underlays,
+		SourceVersionMode: configkit.SourceVersionModeIfPresent,
 		Definition: configkit.Definition[document]{
+			Version: &configkit.VersionRule{
+				Path:  configkit.Keys("version"),
+				Check: checkConfigurationVersion,
+			},
 			Secret: secretProviderPath,
 			Resolve: func(config *document, resolution *configkit.Resolution) error {
-				captureFields(config.Backends, "backends", backendFields, resolution, state.backends)
-				captureFields(config.Profiles, "profiles", profileFields, resolution, state.profiles)
-				resolveBackends(config.Backends, resolution)
-				resolveProfiles(config.Profiles, resolution)
-				resolvePrompts(config.Prompts, resolution)
+				for _, resources := range resourceSets(config) {
+					captureFields(resources.backends, resources.bases.backends, resources.namespace, backendFields, resolution, state.backends)
+					captureFields(resources.profiles, resources.bases.profiles, resources.namespace, profileFields, resolution, state.profiles)
+					capturePromptMetadata(resources.prompts, resources.bases.prompts, resources.namespace, resolution, state.promptMetadata)
+					resolveBackends(resources.backends, resources.bases.backends, resolution)
+					resolveProfiles(resources.profiles, resources.bases.profiles, resolution)
+					resolvePrompts(resources.prompts, resources.bases.prompts, resolution)
+				}
 				return nil
 			},
-			Validate: validateEffective,
+			Validate: func(config *document, validation *configkit.Validation) {
+				validateEffective(config, validation)
+			},
 		},
 	})
 	if err != nil {
@@ -140,14 +261,91 @@ func load(main configkit.Input, underlays []configkit.Underlay) (*loaded, error)
 	if err := state.buildExecutionProfiles(); err != nil {
 		return nil, fmt.Errorf("load configuration: %w", err)
 	}
+	state.backendIDs = sortedKeys(indexedBackends(&result.Config))
+	state.profileIDs = sortedKeys(state.indexedProfiles)
+	for _, id := range sortedKeys(state.prompts) {
+		state.promptIDs = append(state.promptIDs, domain.PromptIdentity{ID: id, Version: stringPointerValue(state.prompts[id].definition.Version)})
+	}
+	state.namespaces = map[string][]string{
+		"backend": resourceNamespaces(state.backendIDs),
+		"profile": resourceNamespaces(state.profileIDs),
+		"prompt":  promptNamespaces(state.promptIDs),
+	}
+	for _, namespace := range sortedKeys(result.Config.Collections) {
+		collection := result.Config.Collections[namespace]
+		state.collections = append(state.collections, CollectionIdentity{
+			Namespace: namespace, ReleaseVersion: stringPointerValue(collection.ReleaseVersion),
+		})
+	}
 	return state, nil
 }
 
-func captureFields[T any](entries map[string]T, collection string, fields []string, resolution *configkit.Resolution, destination map[string]map[string]fieldState) {
+func resourceNamespaces(ids []string) []string {
+	namespaces := make(map[string]struct{})
+	for _, id := range ids {
+		if namespace, _, qualified := strings.Cut(id, "/"); qualified {
+			namespaces[namespace] = struct{}{}
+		}
+	}
+	return sortedKeys(namespaces)
+}
+
+func promptNamespaces(prompts []domain.PromptIdentity) []string {
+	ids := make([]string, len(prompts))
+	for index := range prompts {
+		ids[index] = prompts[index].ID
+	}
+	return resourceNamespaces(ids)
+}
+
+func checkConfigurationVersion(version configkit.Version, validation *configkit.Validation) error {
+	if !version.Present {
+		return nil
+	}
+	if version.Null || version.Text != "1" {
+		validation.Error(configkit.Keys("version"), "unsupported configuration specification version")
+	}
+	return nil
+}
+
+type promptInputPresence struct {
+	contentType fieldState
+	description fieldState
+}
+
+func capturePromptMetadata(prompts map[string]promptConfig, basePath configkit.Path, namespace string, resolution *configkit.Resolution, destination map[string][]promptInputPresence) {
+	for _, id := range sortedKeys(prompts) {
+		inputs := prompts[id].Inputs
+		states := make([]promptInputPresence, len(inputs))
+		base := basePath.Key(id).Key("inputs")
+		for index := range inputs {
+			path := base.Index(index)
+			states[index] = promptInputPresence{
+				contentType: captureFieldState(path.Key("content_type"), resolution),
+				description: captureFieldState(path.Key("description"), resolution),
+			}
+		}
+		destination[indexedResourceID(namespace, id)] = states
+	}
+}
+
+func captureFieldState(path configkit.Path, resolution *configkit.Resolution) fieldState {
+	info, exists := resolution.InputInfo(path)
+	switch {
+	case !exists || !info.Explicit:
+		return fieldAbsent
+	case info.Null:
+		return fieldNull
+	default:
+		return fieldValue
+	}
+}
+
+func captureFields[T any](entries map[string]T, basePath configkit.Path, namespace string, fields []string, resolution *configkit.Resolution, destination map[string]map[string]fieldState) {
 	for id := range entries {
 		states := make(map[string]fieldState, len(fields))
 		for _, field := range fields {
-			info, exists := resolution.InputInfo(configkit.Keys(collection, id, field))
+			info, exists := resolution.InputInfo(basePath.Key(id).Key(field))
 			switch {
 			case !exists || !info.Explicit:
 				states[field] = fieldAbsent
@@ -157,7 +355,7 @@ func captureFields[T any](entries map[string]T, collection string, fields []stri
 				states[field] = fieldValue
 			}
 		}
-		destination[id] = states
+		destination[indexedResourceID(namespace, id)] = states
 	}
 }
 
@@ -178,10 +376,10 @@ func normalizeString(value **string, path configkit.Path, resolution *configkit.
 	return false
 }
 
-func resolveBackends(backends map[string]backendConfig, resolution *configkit.Resolution) {
+func resolveBackends(backends map[string]backendConfig, basePath configkit.Path, resolution *configkit.Resolution) {
 	for _, id := range sortedKeys(backends) {
 		backend := backends[id]
-		base := configkit.Keys("backends", id)
+		base := basePath.Key(id)
 		if backend.Endpoint != nil {
 			endpoint, err := domain.NormalizeOpenAICompatibleBaseEndpoint(*backend.Endpoint)
 			if err != nil {
@@ -193,6 +391,21 @@ func resolveBackends(backends map[string]backendConfig, resolution *configkit.Re
 		if backend.APIKeyEnv != nil {
 			normalizeString(&backend.APIKeyEnv, base.Key("api_key_env"), resolution, strings.TrimSpace(*backend.APIKeyEnv))
 		}
+		if smokeTests := backend.SmokeTests; smokeTests != nil {
+			smokePath := base.Key("smoke_tests")
+			if smokeTests.Reachability != nil {
+				normalizeDiagnosticEndpoint(&smokeTests.Reachability.Endpoint, smokePath.Key("reachability").Key("endpoint"), resolution)
+			}
+			if smokeTests.Authentication != nil {
+				if smokeTests.Authentication.Kind != nil {
+					normalizeString(&smokeTests.Authentication.Kind,
+						smokePath.Key("authentication").Key("kind"), resolution,
+						strings.ToLower(strings.TrimSpace(*smokeTests.Authentication.Kind)))
+				}
+				normalizeDiagnosticEndpoint(&smokeTests.Authentication.Endpoint,
+					smokePath.Key("authentication").Key("endpoint"), resolution)
+			}
+		}
 		if backend.ConcurrencyLimit != nil && *backend.ConcurrencyLimit > 0 && backend.QueueCapacity == nil {
 			capacity := 1024
 			if resolution.IsExplicit(base.Key("queue_capacity")) {
@@ -205,10 +418,25 @@ func resolveBackends(backends map[string]backendConfig, resolution *configkit.Re
 	}
 }
 
-func resolveProfiles(profiles map[string]profileConfig, resolution *configkit.Resolution) {
+func normalizeDiagnosticEndpoint(value **string, path configkit.Path, resolution *configkit.Resolution) {
+	if value == nil || *value == nil {
+		return
+	}
+	normalized := strings.TrimSpace(**value)
+	request, err := http.NewRequest(http.MethodGet, normalized, nil)
+	if normalized == "" || err != nil || request.URL == nil ||
+		(strings.ToLower(request.URL.Scheme) != "http" && strings.ToLower(request.URL.Scheme) != "https") ||
+		request.URL.Hostname() == "" {
+		resolution.Error(path, "diagnostic endpoint must be an absolute HTTP(S) URL with a host")
+		return
+	}
+	normalizeString(value, path, resolution, normalized)
+}
+
+func resolveProfiles(profiles map[string]profileConfig, basePath configkit.Path, resolution *configkit.Resolution) {
 	for _, id := range sortedKeys(profiles) {
 		profile := profiles[id]
-		base := configkit.Keys("profiles", id)
+		base := basePath.Key(id)
 		if profile.Endpoint != nil && *profile.Endpoint != "" {
 			endpoint, err := domain.NormalizeOpenAICompatibleBaseEndpoint(*profile.Endpoint)
 			if err != nil {
@@ -234,68 +462,110 @@ func resolveProfiles(profiles map[string]profileConfig, resolution *configkit.Re
 }
 
 func validateEffective(config *document, validation *configkit.Validation) {
-	for _, id := range sortedKeys(config.Backends) {
-		backend := config.Backends[id]
-		base := configkit.Keys("backends", id)
-		if strings.TrimSpace(id) == "" {
-			validation.Error(base, "backend ID must not be blank")
+	sets := resourceSets(config)
+	backendIDs := make(map[string]struct{})
+	for _, resources := range sets {
+		if resources.isCollection && !domain.IsValidResourceNamespace(resources.namespace) {
+			validation.Error(configkit.Keys("collections", resources.namespace), "collection namespace must be nonblank and contain no slash")
 		}
-		if backend.Endpoint == nil || *backend.Endpoint == "" {
-			validation.Error(base.Key("endpoint"), "endpoint is required")
+		for localKey := range resources.backends {
+			backendIDs[indexedResourceID(resources.namespace, localKey)] = struct{}{}
 		}
-		if backend.APIKeyEnv != nil && *backend.APIKeyEnv != "" && !envName.MatchString(*backend.APIKeyEnv) {
-			validation.Error(base.Key("api_key_env"), "environment variable name is invalid")
-		}
-		if backend.ConcurrencyLimit != nil && *backend.ConcurrencyLimit < 0 {
-			validation.Error(base.Key("concurrency_limit"), "concurrency limit must not be negative")
-		}
-		if backend.QueueCapacity != nil {
-			if *backend.QueueCapacity < 0 {
-				validation.Error(base.Key("queue_capacity"), "queue capacity must not be negative")
-			}
-			if backend.ConcurrencyLimit == nil || *backend.ConcurrencyLimit <= 0 {
-				validation.Error(base.Key("queue_capacity"), "queue capacity requires a positive concurrency limit")
-			} else if *backend.QueueCapacity > int(^uint(0)>>1)-*backend.ConcurrencyLimit {
-				validation.Error(base.Key("queue_capacity"), "total capacity overflows int")
-			}
-		}
-		validateExtraParams(backend.ExtraParams, base.Key("extra_params"), true, validation)
 	}
-	for _, id := range sortedKeys(config.Profiles) {
-		profile := config.Profiles[id]
-		base := configkit.Keys("profiles", id)
-		if strings.TrimSpace(id) == "" {
-			validation.Error(base, "profile ID must not be blank")
-		}
-		if profile.Backend != nil && *profile.Backend != "" {
-			if _, exists := config.Backends[*profile.Backend]; !exists {
-				validation.Error(base.Key("backend"), "backend is not defined")
+	for _, resources := range sets {
+		for _, id := range sortedKeys(resources.backends) {
+			backend := resources.backends[id]
+			base := resources.bases.backends.Key(id)
+			if !domain.IsValidLocalResourceKey(id) {
+				validation.Error(base, "backend key must be a nonblank local key without a slash")
+			}
+			if backend.Endpoint == nil || *backend.Endpoint == "" {
+				validation.Error(base.Key("endpoint"), "endpoint is required")
+			}
+			if backend.APIKeyEnv != nil && *backend.APIKeyEnv != "" && !envName.MatchString(*backend.APIKeyEnv) {
+				validation.Error(base.Key("api_key_env"), "environment variable name is invalid")
+			}
+			if backend.ConcurrencyLimit != nil && *backend.ConcurrencyLimit < 0 {
+				validation.Error(base.Key("concurrency_limit"), "concurrency limit must not be negative")
+			}
+			if backend.QueueCapacity != nil {
+				if *backend.QueueCapacity < 0 {
+					validation.Error(base.Key("queue_capacity"), "queue capacity must not be negative")
+				}
+				if backend.ConcurrencyLimit == nil || *backend.ConcurrencyLimit <= 0 {
+					validation.Error(base.Key("queue_capacity"), "queue capacity requires a positive concurrency limit")
+				} else if *backend.QueueCapacity > int(^uint(0)>>1)-*backend.ConcurrencyLimit {
+					validation.Error(base.Key("queue_capacity"), "total capacity overflows int")
+				}
+			}
+			validateExtraParams(backend.ExtraParams, base.Key("extra_params"), true, validation)
+			if smokeTests := backend.SmokeTests; smokeTests != nil {
+				smokePath := base.Key("smoke_tests")
+				if smokeTests.DefaultProfile != nil {
+					if strings.TrimSpace(*smokeTests.DefaultProfile) == "" {
+						validation.Error(smokePath.Key("default_profile"), "default profile must not be blank")
+					} else if !domain.IsValidResourceID(*smokeTests.DefaultProfile) {
+						validation.Error(smokePath.Key("default_profile"), "default profile reference is malformed")
+					}
+				}
+				if authentication := smokeTests.Authentication; authentication != nil {
+					kindPath := smokePath.Key("authentication").Key("kind")
+					if authentication.Kind == nil {
+						validation.Error(kindPath, "authentication kind is required")
+					} else if *authentication.Kind != "none" && *authentication.Kind != "openrouter_key" {
+						validation.Error(kindPath, "authentication kind must be none or openrouter_key")
+					}
+				}
 			}
 		}
-		if profile.Model != nil && *profile.Model != "" && strings.TrimSpace(*profile.Model) == "" {
-			validation.Error(base.Key("model"), "model must not be blank")
+		for _, id := range sortedKeys(resources.profiles) {
+			profile := resources.profiles[id]
+			base := resources.bases.profiles.Key(id)
+			if !domain.IsValidLocalResourceKey(id) {
+				validation.Error(base, "profile key must be a nonblank local key without a slash")
+			}
+			if profile.Backend != nil && *profile.Backend != "" {
+				if !domain.IsValidResourceID(*profile.Backend) {
+					validation.Error(base.Key("backend"), "backend reference is malformed")
+				} else if _, exists := backendIDs[*profile.Backend]; !exists {
+					validation.Error(base.Key("backend"), "backend is not defined")
+				}
+			}
+			if profile.Model != nil && *profile.Model != "" && strings.TrimSpace(*profile.Model) == "" {
+				validation.Error(base.Key("model"), "model must not be blank")
+			}
+			if profile.Temperature != nil {
+				if err := domain.ValidateExecutionTargetSettings(domain.ExecutionTarget{Temperature: *profile.Temperature}); err != nil {
+					validation.Error(base.Key("temperature"), err.Error())
+				}
+			}
+			if profile.TopP != nil {
+				if err := domain.ValidateExecutionTargetSettings(domain.ExecutionTarget{TopP: *profile.TopP}); err != nil {
+					validation.Error(base.Key("top_p"), err.Error())
+				}
+			}
+			if profile.MaxTokens != nil {
+				if err := domain.ValidateExecutionTargetSettings(domain.ExecutionTarget{MaxTokens: *profile.MaxTokens}); err != nil {
+					validation.Error(base.Key("max_tokens"), err.Error())
+				}
+			}
+			if profile.TimeoutSeconds != nil {
+				if err := domain.ValidateExecutionTargetSettings(domain.ExecutionTarget{TimeoutSeconds: *profile.TimeoutSeconds}); err != nil {
+					validation.Error(base.Key("timeout_seconds"), err.Error())
+				}
+			}
+			validateExtraParams(profile.ExtraParams, base.Key("extra_params"), false, validation)
 		}
-		if profile.Temperature != nil {
-			if err := domain.ValidateExecutionTargetSettings(domain.ExecutionTarget{Temperature: *profile.Temperature}); err != nil {
-				validation.Error(base.Key("temperature"), err.Error())
+		for _, id := range sortedKeys(resources.prompts) {
+			prompt := resources.prompts[id]
+			base := resources.bases.prompts.Key(id)
+			if !domain.IsValidLocalResourceKey(id) {
+				validation.Error(base, "prompt key must be a nonblank local key without a slash")
+			}
+			if prompt.DefaultProfile != nil && *prompt.DefaultProfile != "" && !domain.IsValidResourceID(*prompt.DefaultProfile) {
+				validation.Error(base.Key("default_profile"), "default profile reference is malformed")
 			}
 		}
-		if profile.TopP != nil {
-			if err := domain.ValidateExecutionTargetSettings(domain.ExecutionTarget{TopP: *profile.TopP}); err != nil {
-				validation.Error(base.Key("top_p"), err.Error())
-			}
-		}
-		if profile.MaxTokens != nil {
-			if err := domain.ValidateExecutionTargetSettings(domain.ExecutionTarget{MaxTokens: *profile.MaxTokens}); err != nil {
-				validation.Error(base.Key("max_tokens"), err.Error())
-			}
-		}
-		if profile.TimeoutSeconds != nil {
-			if err := domain.ValidateExecutionTargetSettings(domain.ExecutionTarget{TimeoutSeconds: *profile.TimeoutSeconds}); err != nil {
-				validation.Error(base.Key("timeout_seconds"), err.Error())
-			}
-		}
-		validateExtraParams(profile.ExtraParams, base.Key("extra_params"), false, validation)
 	}
 }
 

internal/configuration/load_test.go

@@ -2,6 +2,7 @@ package configuration
 
 import (
 	"errors"
+	"strings"
 	"testing"
 
 	"gitea.maximumdirect.net/eric/ConfigKit"
@@ -11,40 +12,128 @@ func mapping(label string, values map[string]any) configkit.Input {
 	return configkit.Input{Source: configkit.Mapping(label, values)}
 }
 
+func TestLoadChecksOptionalConfigurationVersion(t *testing.T) {
+	for _, test := range []struct {
+		name    string
+		version any
+		include bool
+		valid   bool
+	}{
+		{name: "string one", version: "1", include: true, valid: true},
+		{name: "integer one", version: int64(1), include: true, valid: true},
+		{name: "omitted", valid: true},
+		{name: "explicit null", include: true},
+		{name: "unsupported string", version: "2", include: true},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			values := map[string]any{}
+			if test.include {
+				values["version"] = test.version
+			}
+			loaded, err := load(mapping("main", values), nil)
+			if test.valid {
+				if err != nil {
+					t.Fatalf("load accepted version: %v", err)
+				}
+				if test.include && (loaded.result.Config.Version == nil || *loaded.result.Config.Version != "1") {
+					t.Fatalf("typed version = %v, want 1", loaded.result.Config.Version)
+				}
+				if !test.include && loaded.result.Config.Version != nil {
+					t.Fatalf("omitted version = %q, want nil", *loaded.result.Config.Version)
+				}
+				return
+			}
+			var loadErr *configkit.LoadError
+			if err == nil || !errors.As(err, &loadErr) {
+				t.Fatalf("load error = %v, want ConfigKit load error", err)
+			}
+			if strings.Contains(err.Error(), "2") {
+				t.Fatalf("load error disclosed the unsupported value: %v", err)
+			}
+			found := false
+			for _, diagnostic := range loadErr.Diagnostics() {
+				if diagnostic.Path.String() == "/version" && diagnostic.Message == "unsupported configuration specification version" {
+					found = true
+				}
+			}
+			if !found {
+				t.Fatalf("load diagnostics = %+v, want safe version diagnostic", loadErr.Diagnostics())
+			}
+		})
+	}
+}
+
+func TestLoadConsumesAcceptedUnderlayVersionAndValidatesHeaderlessPayload(t *testing.T) {
+	underlay := mapping("declared underlay", map[string]any{
+		"version": int64(1),
+	})
+	loaded, err := load(mapping("headerless main", map[string]any{}), []configkit.Underlay{{Inputs: []configkit.Input{underlay}}})
+	if err != nil {
+		t.Fatalf("load accepted non-main declaration: %v", err)
+	}
+	if loaded.result.Config.Version != nil {
+		t.Fatalf("consumed non-main declaration remained in effective payload: %q", *loaded.result.Config.Version)
+	}
+
+	invalidFragment := mapping("headerless prompt fragment", map[string]any{
+		"prompts": map[string]any{"incomplete": map[string]any{"description": "still validated"}},
+	})
+	if _, err := load(configkit.Input{Source: configkit.NoSource()}, []configkit.Underlay{{Inputs: []configkit.Input{invalidFragment}}}); err == nil || !strings.Contains(err.Error(), "at least one message is required") {
+		t.Fatalf("headerless fragment validation error = %v, want final prompt validation", err)
+	}
+}
+
 func TestLoadComposesLiteralKeysAndEffectivePresence(t *testing.T) {
 	base := mapping("defaults", map[string]any{
+		"version": int64(1),
 		"backends": map[string]any{
 			"local.v1": map[string]any{"endpoint": "http://localhost:8080/v1", "concurrency_limit": 2},
 		},
-		"profiles": map[string]any{
-			"base/one": map[string]any{"backend": "local.v1", "temperature": 0.8, "top_p": 0.9, "api_key_required": true,
-				"extra_params": map[string]any{"provider": map[string]any{"first": 1, "second": 2}}},
-			"child.v1": map[string]any{"extends": "base/one"},
-		},
-		"prompts": map[string]any{"invoice/summary": map[string]any{"v1.0": map[string]any{
-			"messages": []any{map[string]any{"role": "user", "content": "Summarize."}},
-			"output":   map[string]any{"format": "text", "validation_mode": "basic"},
-		}}},
+		"collections": map[string]any{"base": map[string]any{
+			"release_version": "",
+			"backends": map[string]any{
+				"local.v1": map[string]any{"endpoint": "http://localhost:8080/v1", "concurrency_limit": 3},
+			},
+			"profiles": map[string]any{
+				"one": map[string]any{"backend": "local.v1", "temperature": 0.8, "top_p": 0.9, "api_key_required": true,
+					"extra_params": map[string]any{"provider": map[string]any{"first": 1, "second": 2}}},
+				"child.v1":   map[string]any{"extends": "one"},
+				"namespaced": map[string]any{"backend": "base/local.v1", "model": "collection-model"},
+			},
+		}, "invoice": map[string]any{
+			"release_version": "r7",
+			"prompts": map[string]any{
+				"summary": map[string]any{
+					"version":  "v1.0",
+					"messages": []any{map[string]any{"role": "user", "content": "Summarize."}},
+					"output":   map[string]any{"format": "text", "validation_mode": "basic"},
+				},
+				"version": map[string]any{
+					"messages": []any{map[string]any{"role": "user", "content": "Nested ID."}},
+					"output":   map[string]any{"format": "text", "validation_mode": "basic"},
+				},
+			},
+		}},
 	})
 	overlay := mapping("operator", map[string]any{
 		"backends": map[string]any{"local.v1": map[string]any{"queue_capacity": 0}},
-		"profiles": map[string]any{"child.v1": map[string]any{
+		"collections": map[string]any{"base": map[string]any{"profiles": map[string]any{"child.v1": map[string]any{
 			"temperature": 0, "top_p": nil, "api_key_required": false,
 			"extra_params": map[string]any{"provider": map[string]any{"second": 3}},
-		}},
+		}}}},
 	})
-	loaded, err := load(configkit.Input{Source: configkit.NoSource()}, []configkit.Underlay{
+	loaded, err := load(mapping("main", map[string]any{"version": "1"}), []configkit.Underlay{
 		{Inputs: []configkit.Input{base}}, {Inputs: []configkit.Input{overlay}},
 	})
 	if err != nil {
 		t.Fatal(err)
 	}
-	profile := loaded.result.Config.Profiles["child.v1"]
+	profile := loaded.result.Config.Collections["base"].Profiles["child.v1"]
 	if profile.Temperature == nil || *profile.Temperature != 0 || profile.TopP != nil || profile.APIKeyRequired == nil || *profile.APIKeyRequired {
 		t.Fatalf("effective values were not retained: %+v", profile)
 	}
-	if loaded.profiles["child.v1"]["temperature"] != fieldValue || loaded.profiles["child.v1"]["top_p"] != fieldNull || loaded.profiles["child.v1"]["api_key_required"] != fieldValue {
-		t.Fatalf("effective presence was lost: %+v", loaded.profiles["child.v1"])
+	if loaded.profiles["base/child.v1"]["temperature"] != fieldValue || loaded.profiles["base/child.v1"]["top_p"] != fieldNull || loaded.profiles["base/child.v1"]["api_key_required"] != fieldValue {
+		t.Fatalf("effective presence was lost: %+v", loaded.profiles["base/child.v1"])
 	}
 	provider := profile.ExtraParams["provider"].(map[string]any)
 	if provider["first"] != int64(1) || provider["second"] != int64(3) {
@@ -54,9 +143,69 @@ func TestLoadComposesLiteralKeysAndEffectivePresence(t *testing.T) {
 	if backend.QueueCapacity == nil || *backend.QueueCapacity != 0 || loaded.backends["local.v1"]["queue_capacity"] != fieldValue {
 		t.Fatalf("explicit zero queue capacity was lost: %+v", backend)
 	}
-	if loaded.result.Config.Prompts["invoice/summary"]["v1.0"].Messages[0].Content == nil {
+	if _, err := loaded.registry.GetBackend("base/local.v1"); err != nil {
+		t.Fatalf("collection backend was not indexed by its full ID: %v", err)
+	}
+	collectionProfile, exists := loaded.indexedProfiles["base/namespaced"]
+	if !exists || collectionProfile.ID != "base/namespaced" || collectionProfile.ResolvedTarget == nil || collectionProfile.ResolvedTarget.BackendID != "base/local.v1" {
+		t.Fatalf("collection profile snapshot = %+v, exists %t", collectionProfile, exists)
+	}
+	if loaded.result.Config.Collections["invoice"].Prompts["summary"].Messages[0].Content == nil || loaded.result.Config.Collections["invoice"].Prompts["summary"].Version == nil || *loaded.result.Config.Collections["invoice"].Prompts["summary"].Version != "v1.0" {
 		t.Fatal("literal prompt ID and version were not decoded")
 	}
+	if loaded.result.Config.Version == nil || *loaded.result.Config.Version != "1" ||
+		loaded.result.Config.Collections["base"].ReleaseVersion == nil || *loaded.result.Config.Collections["base"].ReleaseVersion != "" ||
+		loaded.result.Config.Collections["invoice"].ReleaseVersion == nil || *loaded.result.Config.Collections["invoice"].ReleaseVersion != "r7" {
+		t.Fatalf("root or collection version metadata was not retained: %+v", loaded.result.Config)
+	}
+	if _, _, err := loaded.prompt("invoice/version"); err != nil {
+		t.Fatalf("resource named version was not indexed under its qualified identity: %v", err)
+	}
+}
+
+func TestLoadRejectsInvalidCollectionAndResourceKeys(t *testing.T) {
+	for _, test := range []struct {
+		name    string
+		values  map[string]any
+		message string
+	}{
+		{
+			name:    "namespace with separator",
+			values:  map[string]any{"collections": map[string]any{"bad/name": map[string]any{}}},
+			message: "collection namespace must be nonblank and contain no slash",
+		},
+		{
+			name: "root resource with separator",
+			values: map[string]any{"backends": map[string]any{
+				"bad/name": map[string]any{"endpoint": "https://example.test/v1"},
+			}},
+			message: "backend key must be a nonblank local key without a slash",
+		},
+		{
+			name: "collection resource with separator",
+			values: map[string]any{"collections": map[string]any{"good": map[string]any{
+				"prompts": map[string]any{"bad/name": map[string]any{
+					"messages": []any{map[string]any{"role": "user", "content": "Hello."}},
+					"output":   map[string]any{"format": "text", "validation_mode": "basic"},
+				}},
+			}}},
+			message: "prompt key must be a nonblank local key without a slash",
+		},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			_, err := load(mapping("invalid names", test.values), nil)
+			var loadErr *configkit.LoadError
+			if err == nil || !errors.As(err, &loadErr) {
+				t.Fatalf("load error = %v, want ConfigKit validation error", err)
+			}
+			for _, diagnostic := range loadErr.Diagnostics() {
+				if diagnostic.Message == test.message {
+					return
+				}
+			}
+			t.Fatalf("load diagnostics = %+v, want message %q", loadErr.Diagnostics(), test.message)
+		})
+	}
 }
 
 func TestLoadRecordsBackendNormalizationAndNullDefault(t *testing.T) {
@@ -78,6 +227,159 @@ func TestLoadRecordsBackendNormalizationAndNullDefault(t *testing.T) {
 	}
 }
 
+func TestLoadBackendSmokeTestsOmissionAndNull(t *testing.T) {
+	for _, test := range []struct {
+		name       string
+		smokeTests any
+		include    bool
+		inherited  bool
+	}{
+		{name: "omitted"},
+		{name: "null", smokeTests: nil, include: true, inherited: true},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			backend := map[string]any{"endpoint": "https://backend.example/v1"}
+			if test.include {
+				backend["smoke_tests"] = test.smokeTests
+			}
+			main := mapping("backend", map[string]any{
+				"backends": map[string]any{"local": backend},
+			})
+			var underlays []configkit.Underlay
+			if test.inherited {
+				underlays = []configkit.Underlay{{Inputs: []configkit.Input{mapping("defaults", map[string]any{
+					"backends": map[string]any{"local": map[string]any{
+						"endpoint":    "https://backend.example/v1",
+						"smoke_tests": map[string]any{"default_profile": "inherited-profile"},
+					}},
+				})}}}
+			}
+			loaded, err := load(main, underlays)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if got := loaded.result.Config.Backends["local"].SmokeTests; got != nil {
+				t.Fatalf("smoke_tests = %+v, want nil", got)
+			}
+			selected, err := loaded.registry.GetBackend("local")
+			if err != nil {
+				t.Fatal(err)
+			}
+			if selected.SmokeTests != nil {
+				t.Fatalf("indexed smoke_tests = %+v, want nil", selected.SmokeTests)
+			}
+		})
+	}
+}
+
+func TestLoadMergesBackendSmokeTestsAndRetainsFallbacks(t *testing.T) {
+	base := mapping("defaults", map[string]any{
+		"backends": map[string]any{"local": map[string]any{
+			"endpoint": "https://backend.example/v1",
+			"smoke_tests": map[string]any{
+				"default_profile": "catalog-profile",
+				"reachability":    map[string]any{"endpoint": " https://probe.example/ready?check=1 "},
+				"authentication": map[string]any{
+					"kind":     " OPENROUTER_KEY ",
+					"endpoint": "https://probe.example/key?scope=current",
+				},
+			},
+		}},
+	})
+	overlay := mapping("operator", map[string]any{
+		"backends": map[string]any{"local": map[string]any{
+			"smoke_tests": map[string]any{
+				"default_profile": "not-yet-listed",
+				"authentication":  map[string]any{"kind": " NONE ", "endpoint": nil},
+			},
+		}},
+	})
+	loaded, err := load(configkit.Input{Source: configkit.NoSource()}, []configkit.Underlay{
+		{Inputs: []configkit.Input{base}},
+		{Inputs: []configkit.Input{overlay}},
+	})
+	if err != nil {
+		t.Fatalf("load effective diagnostic metadata: %v", err)
+	}
+	selected, err := loaded.registry.GetBackend("local")
+	if err != nil {
+		t.Fatal(err)
+	}
+	metadata := selected.SmokeTests
+	if selected.Endpoint != "https://backend.example/v1" {
+		t.Fatalf("effective backend endpoint = %q", selected.Endpoint)
+	}
+	if metadata == nil || metadata.DefaultProfile == nil || *metadata.DefaultProfile != "not-yet-listed" {
+		t.Fatalf("default profile overlay was not retained: %+v", metadata)
+	}
+	if metadata.Reachability == nil || metadata.Reachability.Endpoint == nil ||
+		*metadata.Reachability.Endpoint != "https://probe.example/ready?check=1" {
+		t.Fatalf("full reachability destination was not normalized: %+v", metadata.Reachability)
+	}
+	if metadata.Authentication == nil || metadata.Authentication.Kind == nil || *metadata.Authentication.Kind != "none" ||
+		metadata.Authentication.Endpoint != nil {
+		t.Fatalf("authentication overlay or null fallback was not retained: %+v", metadata.Authentication)
+	}
+}
+
+func TestLoadRejectsInvalidFinalBackendSmokeTests(t *testing.T) {
+	for _, test := range []struct {
+		name string
+		data map[string]any
+		path string
+	}{
+		{
+			name: "blank default profile",
+			data: map[string]any{"default_profile": " \t "},
+			path: "/backends/local/smoke_tests/default_profile",
+		},
+		{
+			name: "authentication kind required",
+			data: map[string]any{"authentication": map[string]any{}},
+			path: "/backends/local/smoke_tests/authentication/kind",
+		},
+		{
+			name: "unknown authentication kind",
+			data: map[string]any{"authentication": map[string]any{"kind": "bearer"}},
+			path: "/backends/local/smoke_tests/authentication/kind",
+		},
+		{
+			name: "non-http reachability URL",
+			data: map[string]any{"reachability": map[string]any{"endpoint": "ftp://probe.example/ready"}},
+			path: "/backends/local/smoke_tests/reachability/endpoint",
+		},
+		{
+			name: "blank authentication URL",
+			data: map[string]any{"authentication": map[string]any{"kind": "none", "endpoint": "  "}},
+			path: "/backends/local/smoke_tests/authentication/endpoint",
+		},
+		{
+			name: "relative authentication URL",
+			data: map[string]any{"authentication": map[string]any{"kind": "none", "endpoint": "/key"}},
+			path: "/backends/local/smoke_tests/authentication/endpoint",
+		},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			_, err := load(mapping("backend", map[string]any{
+				"backends": map[string]any{"local": map[string]any{
+					"endpoint":    "https://backend.example/v1",
+					"smoke_tests": test.data,
+				}},
+			}), nil)
+			var loadError *configkit.LoadError
+			if !errors.As(err, &loadError) {
+				t.Fatalf("expected final-value validation error, got %v", err)
+			}
+			for _, diagnostic := range loadError.Diagnostics() {
+				if diagnostic.Path.String() == test.path {
+					return
+				}
+			}
+			t.Fatalf("expected diagnostic at %s, got %+v", test.path, loadError.Diagnostics())
+		})
+	}
+}
+
 func TestLoadDefaultsAbsentQueueCapacity(t *testing.T) {
 	loaded, err := load(mapping("backend", map[string]any{"backends": map[string]any{
 		"local": map[string]any{"endpoint": "http://localhost:8080/v1", "concurrency_limit": 1},
@@ -128,6 +430,40 @@ func TestLoadValidatesOnlyFinalDomainValues(t *testing.T) {
 	}
 }
 
+func TestLoadValidatesOnlyFinalBackendSmokeTestValues(t *testing.T) {
+	underlay := mapping("defaults", map[string]any{
+		"backends": map[string]any{"local": map[string]any{
+			"endpoint": "https://backend.example/v1",
+			"smoke_tests": map[string]any{
+				"default_profile": " ",
+				"reachability":    map[string]any{"endpoint": "ftp://invalid.example/"},
+				"authentication":  map[string]any{"kind": "unsupported"},
+			},
+		}},
+	})
+	main := mapping("operator", map[string]any{
+		"backends": map[string]any{"local": map[string]any{
+			"smoke_tests": map[string]any{
+				"default_profile": "dangling-profile",
+				"reachability":    map[string]any{"endpoint": nil},
+				"authentication":  map[string]any{"kind": "none"},
+			},
+		}},
+	})
+	loaded, err := load(main, []configkit.Underlay{{Inputs: []configkit.Input{underlay}}})
+	if err != nil {
+		t.Fatalf("replaced lower metadata should not fail: %v", err)
+	}
+	selected, err := loaded.registry.GetBackend("local")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if selected.SmokeTests == nil || selected.SmokeTests.DefaultProfile == nil ||
+		*selected.SmokeTests.DefaultProfile != "dangling-profile" {
+		t.Fatalf("final dangling default profile was not retained: %+v", selected.SmokeTests)
+	}
+}
+
 func TestLoadKeepsSyntaxErrorsFromLowerTiers(t *testing.T) {
 	_, err := load(mapping("operator", map[string]any{"backends": map[string]any{"local": map[string]any{"endpoint": "http://localhost:8080"}}}),
 		[]configkit.Underlay{{Inputs: []configkit.Input{{Source: configkit.Bytes("broken", []byte("backends: ["))}}}})

internal/configuration/prompts.go

@@ -16,70 +16,73 @@ import (
 )
 
 var (
-	errPromptNotFound  = errors.New("prompt definition not found")
-	errPromptAmbiguous = errors.New("prompt version is ambiguous")
+	errPromptNotFound = errors.New("prompt definition not found")
 )
 
 type promptEntry struct {
-	definition domain.PromptDefinition
-	inspection domain.PromptInspection
-	hash       string
-	session    *template.Template
-	messages   []*template.Template
+	definition        domain.PromptDefinition
+	inspection        domain.PromptInspection
+	requirementInputs []prompt.InputMetadata
+	hash              string
+	session           *template.Template
+	messages          []*template.Template
 }
 
-func resolvePrompts(prompts map[string]map[string]promptConfig, resolution *configkit.Resolution) {
+func resolvePrompts(prompts map[string]promptConfig, basePath configkit.Path, resolution *configkit.Resolution) {
 	for _, id := range sortedKeys(prompts) {
-		for _, version := range sortedKeys(prompts[id]) {
-			definition := prompts[id][version]
-			base := configkit.Keys("prompts", id, version)
+		definition := prompts[id]
+		base := basePath.Key(id)
+		for _, field := range []struct {
+			name  string
+			value **string
+		}{
+			{"description", &definition.Description},
+			{"session_id", &definition.SessionID},
+		} {
+			if *field.value != nil {
+				normalizeString(field.value, base.Key(field.name), resolution, strings.TrimSpace(**field.value))
+			}
+		}
+		inputsChanged := false
+		for index := range definition.Inputs {
+			input := &definition.Inputs[index]
+			inputPath := base.Key("inputs").Index(index)
+			normalizedName := strings.TrimSpace(input.Name)
+			if normalizedName != input.Name {
+				configkit.Normalize(resolution, inputPath.Key("name"), &input.Name, normalizedName, "normalize input metadata")
+				inputsChanged = true
+			}
 			for _, field := range []struct {
 				name  string
 				value **string
 			}{
-				{"description", &definition.Description},
-				{"session_id", &definition.SessionID},
+				{"content_type", &input.ContentType},
+				{"description", &input.Description},
 			} {
 				if *field.value != nil {
-					normalizeString(field.value, base.Key(field.name), resolution, strings.TrimSpace(**field.value))
-				}
-			}
-			inputsChanged := false
-			for index := range definition.Inputs {
-				input := &definition.Inputs[index]
-				inputPath := base.Key("inputs").Index(index)
-				for _, field := range []struct {
-					name  string
-					value *string
-				}{
-					{"name", &input.Name},
-					{"content_type", &input.ContentType},
-					{"description", &input.Description},
-				} {
-					normalized := strings.TrimSpace(*field.value)
-					if normalized != *field.value {
-						configkit.Normalize(resolution, inputPath.Key(field.name), field.value, normalized, "normalize input metadata")
+					normalized := strings.TrimSpace(**field.value)
+					if normalized != **field.value {
+						configkit.Normalize(resolution, inputPath.Key(field.name), field.value, &normalized, "normalize input metadata")
 						inputsChanged = true
 					}
 				}
 			}
-			if inputsChanged {
-				resolution.Record(base.Key("inputs"), configkit.ChangeNormalization, "normalize input metadata")
-			}
-			// Normalize message metadata on execution-owned copies below. ConfigKit
-			// records sequence mutations as whole-value replacements, which would
-			// discard the effective source contexts of unchanged content_file fields.
-			if definition.Output != nil && definition.Output.SchemaPath != nil {
-				normalizeString(&definition.Output.SchemaPath, base.Key("output").Key("schema_path"), resolution, strings.TrimSpace(*definition.Output.SchemaPath))
-			}
-			prompts[id][version] = definition
 		}
+		if inputsChanged {
+			resolution.Record(base.Key("inputs"), configkit.ChangeNormalization, "normalize input metadata")
+		}
+		// Normalize message metadata on execution-owned copies below. ConfigKit
+		// records sequence mutations as whole-value replacements, which would
+		// discard the effective source contexts of unchanged content_file fields.
+		if definition.Output != nil && definition.Output.SchemaPath != nil {
+			normalizeString(&definition.Output.SchemaPath, base.Key("output").Key("schema_path"), resolution, strings.TrimSpace(*definition.Output.SchemaPath))
+		}
+		prompts[id] = definition
 	}
 }
 
 func (state *loaded) materializePrompts() error {
-	state.prompts = make(map[string]map[string]*promptEntry, len(state.result.Config.Prompts))
-	state.ambiguous = make(map[string]bool)
+	state.prompts = make(map[string]*promptEntry)
 	var metadata *configkit.Metadata
 	lookupOrigin := func(path configkit.Path) (configkit.FieldInfo, bool) {
 		if metadata == nil {
@@ -88,36 +91,29 @@ func (state *loaded) materializePrompts() error {
 		}
 		return metadata.Lookup(path)
 	}
-	for _, id := range sortedKeys(state.result.Config.Prompts) {
-		if strings.TrimSpace(id) == "" {
-			return fmt.Errorf("%s: prompt ID must not be blank", configkit.Keys("prompts", id))
-		}
-		versions := state.result.Config.Prompts[id]
-		if versions == nil {
-			return fmt.Errorf("%s: prompt collection must be a mapping", configkit.Keys("prompts", id))
-		}
-		state.prompts[id] = make(map[string]*promptEntry, len(versions))
-		state.ambiguous[id] = len(versions) > 1
-		for _, version := range sortedKeys(versions) {
-			if strings.TrimSpace(version) == "" {
-				return fmt.Errorf("%s: prompt version must not be blank", configkit.Keys("prompts", id, version))
+	for _, resources := range resourceSets(&state.result.Config) {
+		for _, id := range sortedKeys(resources.prompts) {
+			promptBase := resources.bases.prompts.Key(id)
+			if strings.TrimSpace(id) == "" {
+				return fmt.Errorf("%s: prompt ID must not be blank", promptBase)
 			}
-			entry, err := state.materializePrompt(id, version, versions[version], lookupOrigin)
+			fullID := indexedResourceID(resources.namespace, id)
+			raw := resources.prompts[id]
+			entry, err := state.materializePrompt(fullID, raw.Version, raw, promptBase, lookupOrigin)
 			if err != nil {
 				return err
 			}
-			state.prompts[id][version] = entry
+			state.prompts[fullID] = entry
 		}
 	}
 	return nil
 }
 
-func (state *loaded) materializePrompt(id, version string, raw promptConfig, lookupOrigin func(configkit.Path) (configkit.FieldInfo, bool)) (*promptEntry, error) {
-	base := configkit.Keys("prompts", id, version)
+func (state *loaded) materializePrompt(id string, version *string, raw promptConfig, base configkit.Path, lookupOrigin func(configkit.Path) (configkit.FieldInfo, bool)) (*promptEntry, error) {
 	if len(raw.Messages) == 0 {
 		return nil, fmt.Errorf("%s: at least one message is required", base.Key("messages"))
 	}
-	definition := domain.PromptDefinition{ID: id, Version: version}
+	definition := domain.PromptDefinition{ID: id, Version: stringPointerValue(version)}
 	if raw.DefaultProfile != nil {
 		if strings.TrimSpace(*raw.DefaultProfile) == "" {
 			return nil, fmt.Errorf("%s: default profile must not be blank", base.Key("default_profile"))
@@ -132,6 +128,10 @@ func (state *loaded) materializePrompt(id, version string, raw promptConfig, loo
 	}
 	seenInputs := make(map[string]bool, len(raw.Inputs))
 	definition.Inputs = make([]domain.PromptInput, 0, len(raw.Inputs))
+	entry := &promptEntry{
+		messages:          make([]*template.Template, 0, len(raw.Messages)),
+		requirementInputs: make([]prompt.InputMetadata, 0, len(raw.Inputs)),
+	}
 	for index, input := range raw.Inputs {
 		path := base.Key("inputs").Index(index)
 		if input.Name == "" {
@@ -141,11 +141,27 @@ func (state *loaded) materializePrompt(id, version string, raw promptConfig, loo
 			return nil, fmt.Errorf("%s: input name is duplicated", path.Key("name"))
 		}
 		seenInputs[input.Name] = true
+		contentType := ""
+		if input.ContentType != nil {
+			contentType = *input.ContentType
+		}
+		description := ""
+		if input.Description != nil {
+			description = *input.Description
+		}
 		definition.Inputs = append(definition.Inputs, domain.PromptInput{
-			Name: input.Name, Required: input.Required, ContentType: input.ContentType, Description: input.Description,
+			Name: input.Name, Required: input.Required, ContentType: contentType, Description: description,
 		})
+		presence := state.promptMetadata[id][index]
+		metadata := prompt.InputMetadata{Name: input.Name, Required: input.Required}
+		if presence.contentType == fieldValue {
+			metadata.ContentType = stringPointer(contentType)
+		}
+		if presence.description == fieldValue {
+			metadata.Description = stringPointer(description)
+		}
+		entry.requirementInputs = append(entry.requirementInputs, metadata)
 	}
-	entry := &promptEntry{messages: make([]*template.Template, 0, len(raw.Messages))}
 	definition.Templates = make([]domain.PromptMessageTemplate, 0, len(raw.Messages))
 	for index, message := range raw.Messages {
 		path := base.Key("messages").Index(index)
@@ -226,13 +242,25 @@ func (state *loaded) materializePrompt(id, version string, raw promptConfig, loo
 	entry.definition = definition
 	entry.hash = hash
 	entry.inspection = domain.PromptInspection{
-		PromptID: id, PromptVersion: version, PromptHash: hash,
+		PromptID: id, PromptVersion: stringPointerValue(version), PromptHash: hash,
 		DefaultProfileID: definition.DefaultProfile, Inputs: append([]domain.PromptInput(nil), definition.Inputs...),
 		OutputContract: contract,
 	}
 	return entry, nil
 }
 
+func stringPointer(value string) *string {
+	copy := value
+	return &copy
+}
+
+func stringPointerValue(value *string) *string {
+	if value == nil {
+		return nil
+	}
+	return stringPointer(*value)
+}
+
 func (state *loaded) readContent(fieldPath configkit.Path, name string, lookupOrigin func(configkit.Path) (configkit.FieldInfo, bool)) (string, error) {
 	if strings.TrimSpace(name) == "" {
 		return "", fmt.Errorf("%s: content_file path must not be blank", fieldPath)
@@ -265,24 +293,19 @@ func (state *loaded) readContent(fieldPath configkit.Path, name string, lookupOr
 	return string(content), nil
 }
 
-func (state *loaded) prompt(id, version string) (*domain.PromptDefinition, domain.PromptInspection, error) {
-	if state == nil || strings.TrimSpace(id) == "" || (version != "" && strings.TrimSpace(version) == "") {
-		return nil, domain.PromptInspection{}, errPromptNotFound
+func (state *loaded) lookupPromptEntry(id string) (*promptEntry, error) {
+	if state == nil || strings.TrimSpace(id) == "" {
+		return nil, errPromptNotFound
 	}
-	versions := state.prompts[id]
-	if version == "" {
-		if state.ambiguous[id] {
-			return nil, domain.PromptInspection{}, errPromptAmbiguous
-		}
-		for selected := range versions {
-			version = selected
-		}
-	}
-	entry := versions[version]
+	entry := state.prompts[id]
 	if entry == nil {
-		return nil, domain.PromptInspection{}, errPromptNotFound
+		return nil, errPromptNotFound
 	}
-	definition := entry.definition
+	return entry, nil
+}
+
+func ownPromptDefinition(definition domain.PromptDefinition) *domain.PromptDefinition {
+	definition.Version = stringPointerValue(definition.Version)
 	definition.Inputs = append([]domain.PromptInput(nil), definition.Inputs...)
 	definition.Templates = append([]domain.PromptMessageTemplate(nil), definition.Templates...)
 	for index := range definition.Templates {
@@ -291,41 +314,100 @@ func (state *loaded) prompt(id, version string) (*domain.PromptDefinition, domai
 			definition.Templates[index].CacheControl = &copy
 		}
 	}
-	inspection := entry.inspection
+	return &definition
+}
+
+func ownPromptInspection(inspection domain.PromptInspection) *domain.PromptInspection {
+	inspection.PromptVersion = stringPointerValue(inspection.PromptVersion)
 	inspection.Inputs = append([]domain.PromptInput(nil), inspection.Inputs...)
-	return &definition, inspection, nil
+	return &inspection
+}
+
+func promptLookupError(err error) error {
+	if errors.Is(err, errPromptNotFound) {
+		return promptdef.ErrPromptDefinitionNotFound
+	}
+	return err
+}
+
+func (state *loaded) prompt(id string) (*domain.PromptDefinition, domain.PromptInspection, error) {
+	entry, err := state.lookupPromptEntry(id)
+	if err != nil {
+		return nil, domain.PromptInspection{}, err
+	}
+	return ownPromptDefinition(entry.definition), *ownPromptInspection(entry.inspection), nil
 }
 
 // GetPromptSnapshot returns an independently owned captured definition and its
-// construction-time hash. Lookup retains literal ID and version keys.
-func (state *loaded) GetPromptSnapshot(ctx context.Context, id, version string) (*domain.PromptDefinition, string, error) {
+// construction-time hash.
+func (state *loaded) GetPromptSnapshot(ctx context.Context, id string) (*domain.PromptDefinition, string, error) {
 	if err := ctx.Err(); err != nil {
 		return nil, "", err
 	}
-	definition, inspection, err := state.prompt(id, version)
-	if errors.Is(err, errPromptNotFound) {
-		return nil, "", promptdef.ErrPromptDefinitionNotFound
-	}
+	entry, err := state.lookupPromptEntry(id)
 	if err != nil {
-		return nil, "", err
+		return nil, "", promptLookupError(err)
 	}
-	return definition, inspection.PromptHash, nil
+	return ownPromptDefinition(entry.definition), entry.hash, nil
+}
+
+// GetPromptInspection returns an independently owned inspection of one
+// captured prompt without copying its execution templates.
+func (state *loaded) GetPromptInspection(ctx context.Context, id string) (*domain.PromptInspection, error) {
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	entry, err := state.lookupPromptEntry(id)
+	if err != nil {
+		return nil, promptLookupError(err)
+	}
+	return ownPromptInspection(entry.inspection), nil
 }
 
 // GetPromptDefinition implements the runner's prompt lookup boundary.
-func (state *loaded) GetPromptDefinition(ctx context.Context, id, version string) (*domain.PromptDefinition, error) {
-	definition, _, err := state.GetPromptSnapshot(ctx, id, version)
+func (state *loaded) GetPromptDefinition(ctx context.Context, id string) (*domain.PromptDefinition, error) {
+	definition, _, err := state.GetPromptSnapshot(ctx, id)
 	return definition, err
 }
 
-// GetCompiledTemplates returns construction-time parses for one exact prompt.
-func (state *loaded) GetCompiledTemplates(id, version string) (prompt.CompiledTemplates, bool) {
+// GetCompiledTemplates returns construction-time parses for one prompt ID.
+func (state *loaded) GetCompiledTemplates(id string) (prompt.CompiledTemplates, bool) {
 	if state == nil {
 		return prompt.CompiledTemplates{}, false
 	}
-	entry := state.prompts[id][version]
+	entry := state.prompts[id]
 	if entry == nil {
 		return prompt.CompiledTemplates{}, false
 	}
 	return prompt.CompiledTemplates{Session: entry.session, Messages: entry.messages}, true
 }
+
+// GetRequirementSnapshot returns captured templates and input metadata for
+// one prompt ID. Returned metadata and slices are independently
+// owned; the compiled templates are shared immutable construction-time parses.
+func (state *loaded) GetRequirementSnapshot(id string) (prompt.RequirementSnapshot, bool) {
+	if state == nil {
+		return prompt.RequirementSnapshot{}, false
+	}
+	entry := state.prompts[id]
+	if entry == nil {
+		return prompt.RequirementSnapshot{}, false
+	}
+	snapshot := prompt.RequirementSnapshot{
+		Templates: prompt.CompiledTemplates{
+			Session:  entry.session,
+			Messages: append([]*template.Template(nil), entry.messages...),
+		},
+		Inputs: make([]prompt.InputMetadata, len(entry.requirementInputs)),
+	}
+	for index, input := range entry.requirementInputs {
+		snapshot.Inputs[index] = input
+		if input.ContentType != nil {
+			snapshot.Inputs[index].ContentType = stringPointer(*input.ContentType)
+		}
+		if input.Description != nil {
+			snapshot.Inputs[index].Description = stringPointer(*input.Description)
+		}
+	}
+	return snapshot, true
+}

internal/configuration/prompts_test.go

@@ -1,6 +1,7 @@
 package configuration
 
 import (
+	"context"
 	"errors"
 	"io/fs"
 	"os"
@@ -10,13 +11,16 @@ import (
 	"testing/fstest"
 
 	"gitea.maximumdirect.net/eric/ConfigKit"
+	"gitea.maximumdirect.net/eric/promptkit/internal/promptdef"
 )
 
 func TestLoadCapturesInheritedImportedContent(t *testing.T) {
 	files := fstest.MapFS{
-		"app/main.yaml":     {Data: []byte("configkit:\n  imports:\n    - path: ../catalog/base.yaml\nprompts:\n  child:\n    extends: base\n")},
-		"catalog/base.yaml": {Data: []byte("prompts:\n  base:\n    v1:\n      messages:\n        - role: ' USER '\n          cache_control:\n            type: ' ephemeral '\n            ttl: ' 1h '\n          content_file: ./body.md\n      output:\n        format: text\n        validation_mode: basic\n")},
-		"catalog/body.md":   {Data: []byte("Captured {{.name}}")},
+		"app/main.yaml":         {Data: []byte("configkit:\n  imports:\n    - path: ../catalog/base.yaml\n    - path: ../other/definition.yaml\ncollections:\n  docs:\n    prompts:\n      child:\n        extends: base\n")},
+		"catalog/base.yaml":     {Data: []byte("collections:\n  docs:\n    release_version: r1\n    prompts:\n      base:\n        version: \"v1\"\n        messages:\n          - role: ' USER '\n            cache_control:\n              type: ' ephemeral '\n              ttl: ' 1h '\n            content_file: ./body.md\n        output:\n          format: text\n          validation_mode: basic\n")},
+		"catalog/body.md":       {Data: []byte("Captured {{.name}}")},
+		"other/definition.yaml": {Data: []byte("collections:\n  other:\n    prompts:\n      child:\n        messages:\n          - role: user\n            content_file: ./body.md\n        output:\n          format: text\n          validation_mode: none\n")},
+		"other/body.md":         {Data: []byte("Other collection {{.name}}")},
 	}
 	namespace := configkit.NewFilesystem("embedded", files)
 	state, err := load(configkit.Input{
@@ -30,7 +34,7 @@ func TestLoadCapturesInheritedImportedContent(t *testing.T) {
 		}
 		t.Fatal(err)
 	}
-	definition, inspection, err := state.prompt("child", "")
+	definition, inspection, err := state.prompt("docs/child")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -41,7 +45,7 @@ func TestLoadCapturesInheritedImportedContent(t *testing.T) {
 	if message.Role != "user" || message.CacheControl == nil || message.CacheControl.Type != "ephemeral" || message.CacheControl.TTL != "1h" {
 		t.Fatalf("message metadata was not normalized: %+v", message)
 	}
-	field, ok := state.result.Metadata().Lookup(configkit.Keys("prompts", "child", "v1", "messages").Index(0).Key("content_file"))
+	field, ok := state.result.Metadata().Lookup(configkit.Keys("collections", "docs", "prompts", "child", "messages").Index(0).Key("content_file"))
 	if !ok || len(field.Origin.Locations) != 1 {
 		t.Fatalf("content origin was lost during normalization: %+v", field)
 	}
@@ -54,16 +58,25 @@ func TestLoadCapturesInheritedImportedContent(t *testing.T) {
 	if originPath != "catalog/base.yaml" {
 		t.Fatalf("content origin = %q, want catalog/base.yaml", originPath)
 	}
+	other, otherInspection, err := state.prompt("other/child")
+	if err != nil || other.Templates[0].Content != "Other collection {{.name}}" {
+		t.Fatalf("other collection did not retain its source context: %+v, %v", other, err)
+	}
 	files["catalog/body.md"].Data = []byte("Changed")
-	again, againInspection, err := state.prompt("child", "v1")
+	files["other/body.md"].Data = []byte("Changed other collection")
+	again, againInspection, err := state.prompt("docs/child")
 	if err != nil || again.Templates[0].Content != "Captured {{.name}}" || againInspection.PromptHash != inspection.PromptHash {
 		t.Fatalf("captured definition changed after source mutation: %+v, %+v, %v", again, againInspection, err)
 	}
 	definition.Templates[0].Content = "caller mutation"
-	third, _, err := state.prompt("child", "v1")
+	third, _, err := state.prompt("docs/child")
 	if err != nil || third.Templates[0].Content != "Captured {{.name}}" {
 		t.Fatalf("caller mutation escaped into index: %+v, %v", third, err)
 	}
+	otherAgain, otherAgainInspection, err := state.prompt("other/child")
+	if err != nil || otherAgain.Templates[0].Content != "Other collection {{.name}}" || otherAgainInspection.PromptHash != otherInspection.PromptHash {
+		t.Fatalf("other captured definition changed after source mutation: %+v, %+v, %v", otherAgain, otherAgainInspection, err)
+	}
 }
 
 func TestLoadUsesExplicitMappingContextAndClosesContent(t *testing.T) {
@@ -79,12 +92,12 @@ func TestLoadUsesExplicitMappingContextAndClosesContent(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	definition, _, err := state.prompt("example", "v1")
+	definition, _, err := state.prompt("example")
 	if err != nil || definition.Templates[0].Content != "From mapping" || filesystem.contentOpened != 1 || filesystem.contentClosed != 1 {
 		t.Fatalf("mapping context or handle ownership failed: %+v, opens=%d closes=%d, %v", definition, filesystem.contentOpened, filesystem.contentClosed, err)
 	}
 	_, err = load(mapping("contextless", promptWithFile("body.md")), nil)
-	if err == nil || !strings.Contains(err.Error(), "/prompts/example/v1/messages/0/content_file") {
+	if err == nil || !strings.Contains(err.Error(), "/prompts/example/messages/0/content_file") {
 		t.Fatalf("expected semantic path for contextless resource, got %v", err)
 	}
 }
@@ -93,7 +106,7 @@ func TestLoadCapturesNativeContentFile(t *testing.T) {
 	root := t.TempDir()
 	definitionPath := filepath.Join(root, "definition.yaml")
 	contentPath := filepath.Join(root, "body.md")
-	if err := os.WriteFile(definitionPath, []byte("prompts:\n  example:\n    v1:\n      messages:\n        - role: user\n          content_file: body.md\n      output:\n        format: text\n        validation_mode: basic\n"), 0o600); err != nil {
+	if err := os.WriteFile(definitionPath, []byte("prompts:\n  example:\n    version: \"v1\"\n    messages:\n      - role: user\n        content_file: body.md\n    output:\n      format: text\n      validation_mode: basic\n"), 0o600); err != nil {
 		t.Fatal(err)
 	}
 	if err := os.WriteFile(contentPath, []byte("Native body"), 0o600); err != nil {
@@ -106,41 +119,216 @@ func TestLoadCapturesNativeContentFile(t *testing.T) {
 	if err := os.WriteFile(contentPath, []byte("Modified"), 0o600); err != nil {
 		t.Fatal(err)
 	}
-	definition, _, err := state.prompt("example", "v1")
+	definition, _, err := state.prompt("example")
 	if err != nil || definition.Templates[0].Content != "Native body" {
 		t.Fatalf("native content was not captured: %+v, %v", definition, err)
 	}
 }
 
-func TestLoadRejectsMalformedStaticSyntaxAndAmbiguousSelection(t *testing.T) {
+func TestLoadRejectsMalformedStaticSyntaxAndCapturesOptionalVersion(t *testing.T) {
 	_, err := load(mapping("bad-template", map[string]any{"prompts": map[string]any{"example": map[string]any{
-		"v1": map[string]any{"messages": []any{map[string]any{"role": "user", "content": "{{if}}"}},
-			"output": map[string]any{"format": "text", "validation_mode": "basic"}},
+		"messages": []any{map[string]any{"role": "user", "content": "{{if}}"}},
+		"output":   map[string]any{"format": "text", "validation_mode": "basic"},
 	}}}), nil)
 	if err == nil || !strings.Contains(err.Error(), "invalid template syntax") {
 		t.Fatalf("expected construction-time syntax error, got %v", err)
 	}
-	state, err := load(mapping("versions", map[string]any{"prompts": map[string]any{"example": map[string]any{
-		"v1": map[string]any{"messages": []any{map[string]any{"role": "user", "content": "one"}},
-			"output": map[string]any{"format": "text", "validation_mode": "basic"}},
-		"v2": map[string]any{"messages": []any{map[string]any{"role": "user", "content": "two"}},
-			"output": map[string]any{"format": "text", "validation_mode": "basic"}},
+	state, err := load(mapping("version metadata", map[string]any{"prompts": map[string]any{"example": map[string]any{
+		"version":  "release label",
+		"messages": []any{map[string]any{"role": "user", "content": "one"}},
+		"output":   map[string]any{"format": "text", "validation_mode": "basic"},
 	}}}), nil)
 	if err != nil {
 		t.Fatal(err)
 	}
-	if _, _, err := state.prompt("example", ""); !errors.Is(err, errPromptAmbiguous) {
-		t.Fatalf("expected ambiguous version selection, got %v", err)
+	definition, inspection, err := state.prompt("example")
+	if err != nil || definition.Version == nil || *definition.Version != "release label" ||
+		inspection.PromptVersion == nil || *inspection.PromptVersion != "release label" {
+		t.Fatalf("optional version metadata was not retained: definition=%+v inspection=%+v err=%v", definition, inspection, err)
+	}
+}
+
+func TestPromptVersionLabelPresenceAndOwnership(t *testing.T) {
+	tests := []struct {
+		name        string
+		version     any
+		include     bool
+		wantPresent bool
+		wantValue   string
+	}{
+		{name: "absent"},
+		{name: "null", include: true},
+		{name: "empty", version: "", include: true, wantPresent: true},
+		{name: "exact text", version: " Release/v1 ", include: true, wantPresent: true, wantValue: " Release/v1 "},
+	}
+
+	hashes := make(map[string]string, len(tests))
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			definition := map[string]any{
+				"messages": []any{map[string]any{"role": "user", "content": "hello"}},
+				"output":   map[string]any{"format": "text", "validation_mode": "basic"},
+			}
+			if test.include {
+				definition["version"] = test.version
+			}
+			state, err := load(mapping("prompt version label", map[string]any{
+				"prompts": map[string]any{"example": definition},
+			}), nil)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			captured, inspection, err := state.prompt("example")
+			if err != nil {
+				t.Fatal(err)
+			}
+			identities, err := state.ListPrompts(context.Background())
+			if err != nil || len(identities) != 1 {
+				t.Fatalf("list prompt labels: %#v, %v", identities, err)
+			}
+			check := func(name string, value *string) {
+				t.Helper()
+				if !test.wantPresent {
+					if value != nil {
+						t.Errorf("%s label = %q, want absent", name, *value)
+					}
+					return
+				}
+				if value == nil || *value != test.wantValue {
+					t.Errorf("%s label = %v, want %q", name, value, test.wantValue)
+				}
+			}
+			check("definition", captured.Version)
+			check("inspection", inspection.PromptVersion)
+			check("listing", identities[0].Version)
+			if captured.Version != nil && (captured.Version == inspection.PromptVersion || captured.Version == identities[0].Version || inspection.PromptVersion == identities[0].Version) {
+				t.Fatal("returned prompt labels share mutable pointers")
+			}
+			hashes[test.name] = inspection.PromptHash
+
+			if captured.Version != nil {
+				*captured.Version = "mutated definition"
+			}
+			if inspection.PromptVersion != nil {
+				*inspection.PromptVersion = "mutated inspection"
+			}
+			if identities[0].Version != nil {
+				*identities[0].Version = "mutated listing"
+			}
+			again, againInspection, err := state.prompt("example")
+			if err != nil {
+				t.Fatal(err)
+			}
+			check("captured definition after mutation", again.Version)
+			check("captured inspection after mutation", againInspection.PromptVersion)
+		})
+	}
+	if hashes["absent"] == hashes["empty"] {
+		t.Fatal("absent and declared-empty labels produced the same definition hash")
+	}
+}
+
+func TestPromptVersionNullClearsInheritedLabel(t *testing.T) {
+	prompt := map[string]any{
+		"version":  "base-label",
+		"messages": []any{map[string]any{"role": "user", "content": "hello"}},
+		"output":   map[string]any{"format": "text", "validation_mode": "basic"},
+	}
+	state, err := load(
+		mapping("clear inherited label", map[string]any{"prompts": map[string]any{"example": map[string]any{"version": nil}}}),
+		[]configkit.Underlay{{Inputs: []configkit.Input{mapping("base prompt", map[string]any{"prompts": map[string]any{"example": prompt}})}}},
+	)
+	if err != nil {
+		t.Fatal(err)
+	}
+	definition, inspection, err := state.prompt("example")
+	if err != nil || definition.Version != nil || inspection.PromptVersion != nil {
+		t.Fatalf("null overlay retained inherited label: definition=%+v inspection=%+v err=%v", definition, inspection, err)
+	}
+}
+
+func TestPromptInspectionLookupMatchesSnapshotSelectionAndOwnsInputs(t *testing.T) {
+	makePrompt := func(content string) map[string]any {
+		return map[string]any{
+			"default_profile": "partial",
+			"inputs": []any{map[string]any{
+				"name": "document", "required": true,
+				"content_type": " text/plain ", "description": " source document ",
+			}},
+			"messages": []any{map[string]any{"role": "user", "content": content}},
+			"output":   map[string]any{"format": "text", "validation_mode": "none"},
+		}
+	}
+	selectedPrompt := makePrompt("selected")
+	selectedPrompt["version"] = "v2"
+	state, err := load(mapping("prompt inspection lookup", map[string]any{
+		"profiles": map[string]any{"partial": map[string]any{}},
+		"prompts": map[string]any{
+			"selected": selectedPrompt,
+		},
+	}), nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	{
+		inspection, err := state.GetPromptInspection(context.Background(), "selected")
+		if err != nil {
+			t.Fatalf("inspect prompt ID: %v", err)
+		}
+		definition, hash, err := state.GetPromptSnapshot(context.Background(), "selected")
+		if err != nil {
+			t.Fatalf("snapshot prompt ID: %v", err)
+		}
+		if inspection.PromptID != definition.ID || inspection.PromptVersion == nil || definition.Version == nil ||
+			*inspection.PromptVersion != *definition.Version ||
+			inspection.PromptHash != hash || inspection.DefaultProfileID != "partial" ||
+			len(inspection.Inputs) != 1 || inspection.Inputs[0].Name != "document" ||
+			inspection.Inputs[0].ContentType != "text/plain" || inspection.Inputs[0].Description != "source document" {
+			t.Fatalf("inspection did not match the selected snapshot: inspection=%+v definition=%+v hash=%q", inspection, definition, hash)
+		}
+		if len(definition.Inputs) != len(inspection.Inputs) || definition.Inputs[0].Name != inspection.Inputs[0].Name {
+			t.Fatalf("definition and inspection inputs diverged: definition=%+v inspection=%+v", definition.Inputs, inspection.Inputs)
+		}
+	}
+
+	owned, err := state.GetPromptInspection(context.Background(), "selected")
+	if err != nil {
+		t.Fatal(err)
+	}
+	owned.Inputs[0].Name = "caller mutation"
+	owned.Inputs[0].Description = "caller mutation"
+	again, err := state.GetPromptInspection(context.Background(), "selected")
+	if err != nil || again.Inputs[0].Name != "document" || again.Inputs[0].Description != "source document" {
+		t.Fatalf("inspection mutation escaped into captured state: inspection=%+v err=%v", again, err)
+	}
+
+	for _, id := range []string{"missing", " "} {
+		inspection, err := state.GetPromptInspection(context.Background(), id)
+		if inspection != nil || !errors.Is(err, promptdef.ErrPromptDefinitionNotFound) {
+			t.Errorf("inspection lookup %q=(%+v, %v), want not found", id, inspection, err)
+		}
+		definition, _, err := state.GetPromptSnapshot(context.Background(), id)
+		if definition != nil || !errors.Is(err, promptdef.ErrPromptDefinitionNotFound) {
+			t.Errorf("snapshot lookup %q=(%+v, %v), want not found", id, definition, err)
+		}
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+	if _, err := state.GetPromptInspection(ctx, "selected"); !errors.Is(err, context.Canceled) {
+		t.Errorf("canceled inspection selection error=%v", err)
 	}
 }
 
 func TestLoadAcceptsEmptyInlineContentAndRejectsInvalidPromptFields(t *testing.T) {
-	state, err := load(mapping("empty-content", map[string]any{"prompts": map[string]any{" exact.id ": map[string]any{"v1": map[string]any{
-		"inputs": []any{map[string]any{"name": " note ", "required": true}},
+	state, err := load(mapping("empty-content", map[string]any{"prompts": map[string]any{" exact.id ": map[string]any{
+		"version": "v1",
+		"inputs":  []any{map[string]any{"name": " note ", "required": true}},
 		"messages": []any{map[string]any{"role": " USER ", "content": "", "content_file": nil,
 			"cache_control": map[string]any{"type": " ephemeral ", "ttl": "1h "}}},
 		"output": map[string]any{"format": "text", "validation_mode": "basic"},
-	}}}}), nil)
+	}}}), nil)
 	if err != nil {
 		var loadError *configkit.LoadError
 		if errors.As(err, &loadError) {
@@ -148,18 +336,19 @@ func TestLoadAcceptsEmptyInlineContentAndRejectsInvalidPromptFields(t *testing.T
 		}
 		t.Fatal(err)
 	}
-	definition, _, err := state.prompt(" exact.id ", "v1")
+	definition, _, err := state.prompt(" exact.id ")
 	if err != nil || definition.ID != " exact.id " || definition.Templates[0].Content != "" || definition.Templates[0].Role != "user" ||
 		definition.Inputs[0].Name != "note" || definition.Templates[0].CacheControl.TTL != "1h" {
 		t.Fatalf("explicit empty content or literal ID was changed: %+v, %v", definition, err)
 	}
-	if _, _, err := state.prompt("exact.id", "v1"); !errors.Is(err, errPromptNotFound) {
+	if _, _, err := state.prompt("exact.id"); !errors.Is(err, errPromptNotFound) {
 		t.Fatalf("trimmed prompt identity unexpectedly matched: %v", err)
 	}
-	_, err = load(mapping("obsolete-field", map[string]any{"prompts": map[string]any{"example": map[string]any{"v1": map[string]any{
-		"id": "example", "messages": []any{map[string]any{"role": "user", "content": "ok"}},
+	_, err = load(mapping("obsolete-field", map[string]any{"prompts": map[string]any{"example": map[string]any{
+		"version": "v1",
+		"id":      "example", "messages": []any{map[string]any{"role": "user", "content": "ok"}},
 		"output": map[string]any{"format": "text", "validation_mode": "basic"},
-	}}}}), nil)
+	}}}), nil)
 	var loadError *configkit.LoadError
 	if !errors.As(err, &loadError) {
 		t.Fatalf("obsolete identity field should fail strict decoding: %v", err)
@@ -170,11 +359,117 @@ func TestLoadAcceptsEmptyInlineContentAndRejectsInvalidPromptFields(t *testing.T
 	}
 }
 
+func TestRequirementSnapshotCapturesMetadataPresenceAndNormalizedValues(t *testing.T) {
+	state, err := load(mapping("requirement-metadata", map[string]any{
+		"prompts": map[string]any{"example": map[string]any{
+			"version":    "v1",
+			"session_id": "{{.session}}",
+			"inputs": []any{
+				map[string]any{"name": "absent"},
+				map[string]any{"name": "null", "content_type": nil, "description": nil},
+				map[string]any{"name": "empty", "content_type": "", "description": ""},
+				map[string]any{"name": "normalized", "content_type": " text/plain ", "description": "  final text  "},
+			},
+			"messages": []any{map[string]any{"role": "user", "content": "{{input \"absent\"}}"}},
+			"output":   map[string]any{"format": "text", "validation_mode": "basic"},
+		}},
+	}), nil)
+	if err != nil {
+		var loadError *configkit.LoadError
+		if errors.As(err, &loadError) {
+			t.Fatalf("%v: %+v", err, loadError.Diagnostics())
+		}
+		t.Fatal(err)
+	}
+
+	snapshot, ok := state.GetRequirementSnapshot("example")
+	if !ok || len(snapshot.Inputs) != 4 || len(snapshot.Templates.Messages) != 1 || snapshot.Templates.Session == nil {
+		t.Fatalf("requirement snapshot was not captured: %+v, %t", snapshot, ok)
+	}
+	for _, index := range []int{0, 1} {
+		if snapshot.Inputs[index].ContentType != nil || snapshot.Inputs[index].Description != nil {
+			t.Errorf("input %q should not have explicit string metadata: %+v", snapshot.Inputs[index].Name, snapshot.Inputs[index])
+		}
+	}
+	if snapshot.Inputs[2].ContentType == nil || *snapshot.Inputs[2].ContentType != "" ||
+		snapshot.Inputs[2].Description == nil || *snapshot.Inputs[2].Description != "" {
+		t.Errorf("explicit empty metadata presence was lost: %+v", snapshot.Inputs[2])
+	}
+	if snapshot.Inputs[3].ContentType == nil || *snapshot.Inputs[3].ContentType != "text/plain" ||
+		snapshot.Inputs[3].Description == nil || *snapshot.Inputs[3].Description != "final text" {
+		t.Errorf("snapshot did not use normalized final metadata: %+v", snapshot.Inputs[3])
+	}
+
+	definition, inspection, err := state.prompt("example")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(definition.Inputs) != 4 || len(inspection.Inputs) != 4 || inspection.Inputs[2].ContentType != "" || inspection.Inputs[2].Description != "" ||
+		inspection.Inputs[3].ContentType != "text/plain" || inspection.Inputs[3].Description != "final text" {
+		t.Fatalf("existing prompt inspection shape or normalized values changed: %+v", inspection)
+	}
+
+	*snapshot.Inputs[2].ContentType = "caller mutation"
+	snapshot.Inputs[3].Name = "caller mutation"
+	snapshot.Templates.Messages[0] = nil
+	again, ok := state.GetRequirementSnapshot("example")
+	if !ok || *again.Inputs[2].ContentType != "" || again.Inputs[3].Name != "normalized" || again.Templates.Messages[0] == nil {
+		t.Fatalf("snapshot mutation escaped into captured state: %+v, %t", again, ok)
+	}
+}
+
+func TestInputMetadataPresenceDoesNotChangePromptHashOrInspection(t *testing.T) {
+	variants := []struct {
+		name   string
+		fields map[string]any
+	}{
+		{name: "absent"},
+		{name: "null", fields: map[string]any{"content_type": nil, "description": nil}},
+		{name: "empty", fields: map[string]any{"content_type": "", "description": ""}},
+	}
+	var expectedHash string
+	for _, variant := range variants {
+		t.Run(variant.name, func(t *testing.T) {
+			input := map[string]any{"name": "document"}
+			for name, value := range variant.fields {
+				input[name] = value
+			}
+			state, err := load(mapping("hash-"+variant.name, map[string]any{
+				"prompts": map[string]any{"same": map[string]any{
+					"version":  "v1",
+					"inputs":   []any{input},
+					"messages": []any{map[string]any{"role": "user", "content": "hello"}},
+					"output":   map[string]any{"format": "text", "validation_mode": "basic"},
+				}},
+			}), nil)
+			if err != nil {
+				var loadError *configkit.LoadError
+				if errors.As(err, &loadError) {
+					t.Fatalf("%v: %+v", err, loadError.Diagnostics())
+				}
+				t.Fatal(err)
+			}
+			_, inspection, err := state.prompt("same")
+			if err != nil {
+				t.Fatal(err)
+			}
+			if len(inspection.Inputs) != 1 || inspection.Inputs[0].ContentType != "" || inspection.Inputs[0].Description != "" {
+				t.Fatalf("old inspection metadata changed: %+v", inspection.Inputs)
+			}
+			if expectedHash == "" {
+				expectedHash = inspection.PromptHash
+			} else if inspection.PromptHash != expectedHash {
+				t.Fatalf("metadata presence changed the definition hash: got %q, want %q", inspection.PromptHash, expectedHash)
+			}
+		})
+	}
+}
+
 func promptWithFile(name string) map[string]any {
-	return map[string]any{"prompts": map[string]any{"example": map[string]any{"v1": map[string]any{
+	return map[string]any{"prompts": map[string]any{"example": map[string]any{
 		"messages": []any{map[string]any{"role": "user", "content_file": name}},
 		"output":   map[string]any{"format": "text", "validation_mode": "basic"},
-	}}}}
+	}}}
 }
 
 type countingFS struct {

internal/configuration/targets.go

@@ -12,14 +12,25 @@ import (
 )
 
 func (state *loaded) buildExecutionProfiles() error {
-	definitions := make(map[string]domain.Backend, len(state.result.Config.Backends))
-	for _, id := range sortedKeys(state.result.Config.Backends) {
-		config := state.result.Config.Backends[id]
-		params, err := jsonvalue.CopyMap(config.ExtraParams)
-		if err != nil {
-			return fmt.Errorf("backend %q extra parameters: %w", id, err)
+	backendConfigs := indexedBackends(&state.result.Config)
+	profileConfigs := indexedProfiles(&state.result.Config)
+	definitions := make(map[string]domain.Backend, len(backendConfigs))
+	for _, id := range sortedKeys(backendConfigs) {
+		config := backendConfigs[id]
+		definition := domain.Backend{ID: id, ExtraParams: config.ExtraParams}
+		if config.SmokeTests != nil {
+			smokeTests := &domain.BackendSmokeTestConfig{DefaultProfile: config.SmokeTests.DefaultProfile}
+			if config.SmokeTests.Reachability != nil {
+				smokeTests.Reachability = &domain.ReachabilityProbeConfig{Endpoint: config.SmokeTests.Reachability.Endpoint}
+			}
+			if config.SmokeTests.Authentication != nil {
+				smokeTests.Authentication = &domain.AuthenticationProbeConfig{
+					Kind:     config.SmokeTests.Authentication.Kind,
+					Endpoint: config.SmokeTests.Authentication.Endpoint,
+				}
+			}
+			definition.SmokeTests = smokeTests
 		}
-		definition := domain.Backend{ID: id, ExtraParams: params}
 		if config.Endpoint != nil {
 			definition.Endpoint = *config.Endpoint
 		}
@@ -40,9 +51,9 @@ func (state *loaded) buildExecutionProfiles() error {
 		return err
 	}
 	state.registry = registry
-	state.indexedProfiles = make(map[string]domain.ExecutionProfile, len(state.result.Config.Profiles))
-	for _, id := range sortedKeys(state.result.Config.Profiles) {
-		config := state.result.Config.Profiles[id]
+	state.indexedProfiles = make(map[string]domain.ExecutionProfile, len(profileConfigs))
+	for _, id := range sortedKeys(profileConfigs) {
+		config := profileConfigs[id]
 		fields := state.profiles[id]
 		target := defaults.ExecutionTargetDefault()
 		if config.Backend != nil && *config.Backend != "" {
@@ -147,18 +158,26 @@ func overlayProviderMap(lower, upper map[string]any) (map[string]any, error) {
 	return merged, nil
 }
 
-// GetProfile returns an independently owned indexed profile for the internal
-// runner's lookup boundary.
-func (state *loaded) GetProfile(ctx context.Context, id string) (*domain.ExecutionProfile, error) {
+func (state *loaded) lookupProfile(ctx context.Context, id string) (domain.ExecutionProfile, error) {
 	if err := ctx.Err(); err != nil {
-		return nil, err
+		return domain.ExecutionProfile{}, err
 	}
 	if state == nil {
-		return nil, fmt.Errorf("%w: %q", profilepkg.ErrProfileNotFound, id)
+		return domain.ExecutionProfile{}, fmt.Errorf("%w: %q", profilepkg.ErrProfileNotFound, id)
 	}
 	profile, found := state.indexedProfiles[id]
 	if !found {
-		return nil, fmt.Errorf("%w: %q", profilepkg.ErrProfileNotFound, id)
+		return domain.ExecutionProfile{}, fmt.Errorf("%w: %q", profilepkg.ErrProfileNotFound, id)
+	}
+	return profile, nil
+}
+
+// GetProfile returns an independently owned indexed profile for the internal
+// runner's lookup boundary.
+func (state *loaded) GetProfile(ctx context.Context, id string) (*domain.ExecutionProfile, error) {
+	profile, err := state.lookupProfile(ctx, id)
+	if err != nil {
+		return nil, err
 	}
 	target := *profile.ResolvedTarget
 	params, err := jsonvalue.CopyMap(target.ExtraParams)
@@ -170,6 +189,15 @@ func (state *loaded) GetProfile(ctx context.Context, id string) (*domain.Executi
 	return &profile, nil
 }
 
+// GetProfileIdentity returns the exact lookup ID for a captured profile
+// without copying its execution target.
+func (state *loaded) GetProfileIdentity(ctx context.Context, id string) (string, error) {
+	if _, err := state.lookupProfile(ctx, id); err != nil {
+		return "", err
+	}
+	return id, nil
+}
+
 // GetBackend returns an independently owned effective backend definition.
 func (state *loaded) GetBackend(id string) (domain.Backend, error) {
 	if state == nil {

internal/configuration/targets_test.go

@@ -3,6 +3,7 @@ package configuration
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"net/http"
 	"net/http/httptest"
 	"reflect"
@@ -11,6 +12,7 @@ import (
 	"gitea.maximumdirect.net/eric/promptkit/internal/defaults"
 	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
 	"gitea.maximumdirect.net/eric/promptkit/internal/llm"
+	profilepkg "gitea.maximumdirect.net/eric/promptkit/internal/profile"
 )
 
 func TestLoadBuildsEffectiveTargetsAfterInheritance(t *testing.T) {
@@ -89,6 +91,18 @@ func TestLoadBuildsEffectiveTargetsAfterInheritance(t *testing.T) {
 	if partial.ResolvedTarget.Endpoint != "" || partial.ResolvedTarget.Model != "" {
 		t.Fatalf("partial profile gained a runnable target: %+v", partial.ResolvedTarget)
 	}
+	identity, err := state.GetProfileIdentity(context.Background(), "partial")
+	if err != nil || identity != "partial" {
+		t.Fatalf("partial profile identity=(%q, %v)", identity, err)
+	}
+	if _, err := state.GetProfileIdentity(context.Background(), "missing"); !errors.Is(err, profilepkg.ErrProfileNotFound) {
+		t.Fatalf("missing profile identity error=%v", err)
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+	if _, err := state.GetProfileIdentity(ctx, "partial"); !errors.Is(err, context.Canceled) {
+		t.Fatalf("canceled profile identity lookup error=%v", err)
+	}
 	endpointOnly, _ := state.GetProfile(context.Background(), "endpoint-only")
 	if endpointOnly.ResolvedTarget.Endpoint != "https://standalone.example/v1" ||
 		endpointOnly.ResolvedTarget.BackendID != "" || endpointOnly.ResolvedTarget.Model != "" {

internal/domain/domain.go

@@ -61,7 +61,6 @@ type CacheControl struct {
 // RunRequest represents a request to generate a single artifact.
 type RunRequest struct {
 	PromptID         string
-	PromptVersion    string
 	ProfileID        string
 	SessionID        string
 	APIKey           string `json:"-" yaml:"-"`
@@ -81,7 +80,7 @@ type RunResult struct {
 	RawOutput            string
 	Validation           ValidationResult
 	PromptID             string
-	PromptVersion        string
+	PromptVersion        *string
 	PromptHash           string
 	SessionID            string
 	RenderedPromptHash   string
@@ -101,7 +100,7 @@ type RunResult struct {
 // It must never include resolved API key values, model output, or validation data.
 type PreparedRun struct {
 	PromptID             string
-	PromptVersion        string
+	PromptVersion        *string
 	PromptHash           string
 	SelectedProfileID    string
 	SelectedBackendID    string
@@ -135,10 +134,16 @@ type Artifact struct {
 	Hash        string
 }
 
+// PromptIdentity identifies one configured prompt and its descriptive version label.
+type PromptIdentity struct {
+	ID      string
+	Version *string
+}
+
 // PromptDefinition represents a configured prompt execution definition.
 type PromptDefinition struct {
 	ID             string                  `yaml:"id"`
-	Version        string                  `yaml:"version"`
+	Version        *string                 `yaml:"version"`
 	DefaultProfile string                  `yaml:"default_profile"`
 	Description    string                  `yaml:"description"`
 	SessionID      string                  `yaml:"session_id" json:"session_id,omitempty"`
@@ -151,7 +156,7 @@ type PromptDefinition struct {
 // PromptInspection is the resolved result of exact prompt inspection.
 type PromptInspection struct {
 	PromptID         string
-	PromptVersion    string
+	PromptVersion    *string
 	PromptHash       string
 	DefaultProfileID string
 	Inputs           []PromptInput
@@ -174,12 +179,14 @@ type PromptMessageTemplate struct {
 	CacheControl *CacheControl `yaml:"cache_control,omitempty" json:"cache_control,omitempty"`
 }
 
-// Backend describes reusable OpenAI-compatible connection defaults.
+// Backend describes reusable OpenAI-compatible connection defaults and optional
+// diagnostic metadata.
 type Backend struct {
 	ID               string
 	Endpoint         string
 	APIKeyEnv        string
 	ExtraParams      map[string]any
+	SmokeTests       *BackendSmokeTestConfig
 	ConcurrencyLimit int
 	QueueCapacity    int
 	QueueCapacitySet bool

internal/domain/observation.go

@@ -68,7 +68,7 @@ type ExecutionEvent struct {
 	RunID              string
 	Time               time.Time
 	PromptID           string
-	PromptVersion      string
+	PromptVersion      *string
 	ProfileID          string
 	BackendID          string
 	Model              string

internal/domain/requirements.go

@@ -0,0 +1,58 @@
+package domain
+
+// RequirementKind classifies how a prompt may depend on an input or variable.
+type RequirementKind string
+
+const (
+	RequirementRequired    RequirementKind = "required"
+	RequirementConditional RequirementKind = "conditional"
+	RequirementOptional    RequirementKind = "optional"
+)
+
+// InputRequirement describes one declared or template-referenced input.
+type InputRequirement struct {
+	Name        string
+	Kind        RequirementKind
+	Declared    bool
+	ContentType *string
+	Description *string
+	Explanation string
+}
+
+// VariableRequirement describes one caller variable referenced by a prompt.
+type VariableRequirement struct {
+	Name        string
+	Kind        RequirementKind
+	Supplied    bool
+	Explanation string
+}
+
+// RequirementIssueCode identifies a limit that may affect requirement
+// discovery.
+type RequirementIssueCode string
+
+const (
+	RequirementIssueMissingVariable      RequirementIssueCode = "missing_variable"
+	RequirementIssueInputContent         RequirementIssueCode = "input_content"
+	RequirementIssueDynamicInputName     RequirementIssueCode = "dynamic_input_name"
+	RequirementIssueUnsupportedConstruct RequirementIssueCode = "unsupported_construct"
+)
+
+// RequirementIssue describes one limitation on requirement discovery.
+type RequirementIssue struct {
+	Code         RequirementIssueCode
+	InputName    string
+	VariableName string
+	Description  string
+}
+
+// RequirementInspection contains the inventories discovered for one prompt.
+type RequirementInspection struct {
+	PromptID      string
+	PromptVersion *string
+	ProfileID     string
+	Inputs        []InputRequirement
+	Variables     []VariableRequirement
+	Complete      bool
+	Issues        []RequirementIssue
+}

internal/domain/resource_identity.go

@@ -0,0 +1,70 @@
+package domain
+
+import "strings"
+
+func validResourceID(id string) bool {
+	if !strings.Contains(id, "/") {
+		return strings.TrimSpace(id) != ""
+	}
+	if strings.Count(id, "/") != 1 {
+		return false
+	}
+	namespace, localID, _ := strings.Cut(id, "/")
+	return namespace != "" && localID != ""
+}
+
+func validResourceNamespace(namespace string) bool {
+	return strings.TrimSpace(namespace) != "" && !strings.Contains(namespace, "/")
+}
+
+func validLocalResourceKey(key string) bool {
+	return strings.TrimSpace(key) != "" && !strings.Contains(key, "/")
+}
+
+func qualifyResourceID(id, namespace string) (string, bool) {
+	if !validResourceID(id) || (namespace != "" && !validResourceNamespace(namespace)) {
+		return "", false
+	}
+	if strings.Contains(id, "/") || namespace == "" {
+		return id, true
+	}
+	return namespace + "/" + id, true
+}
+
+func resourceNamespaceFromID(id string) (string, bool) {
+	if !validResourceID(id) || !strings.Contains(id, "/") {
+		return "", false
+	}
+	namespace, _, _ := strings.Cut(id, "/")
+	return namespace, true
+}
+
+// IsValidResourceID reports whether id is an unqualified resource ID or one
+// valid namespace/local-ID pair.
+func IsValidResourceID(id string) bool { return validResourceID(id) }
+
+// QualifyResourceID validates id and applies namespace to an unqualified ID.
+// An already-qualified ID is returned unchanged.
+func QualifyResourceID(id, namespace string) (string, bool) {
+	return qualifyResourceID(id, namespace)
+}
+
+// IsValidResourceNamespace reports whether namespace is nonblank and contains
+// no namespace separator.
+func IsValidResourceNamespace(namespace string) bool { return validResourceNamespace(namespace) }
+
+// IsValidLocalResourceKey reports whether key is a nonblank key for a
+// namespace-local resource mapping.
+func IsValidLocalResourceKey(key string) bool { return validLocalResourceKey(key) }
+
+// QualifyLocalResourceID combines a validated namespace and local mapping key.
+// An empty namespace leaves a valid unqualified key unchanged.
+func QualifyLocalResourceID(namespace, key string) (string, bool) {
+	if !validLocalResourceKey(key) || (namespace != "" && !validResourceNamespace(namespace)) {
+		return "", false
+	}
+	if namespace == "" {
+		return key, true
+	}
+	return namespace + "/" + key, true
+}

internal/domain/resource_identity_test.go

@@ -0,0 +1,110 @@
+package domain
+
+import "testing"
+
+func TestValidResourceID(t *testing.T) {
+	tests := []struct {
+		name string
+		id   string
+		want bool
+	}{
+		{name: "ordinary", id: "draft", want: true},
+		{name: "dotted", id: "group.prompt.v2", want: true},
+		{name: "preserved surrounding whitespace", id: " draft ", want: true},
+		{name: "qualified", id: "group/draft", want: true},
+		{name: "qualified components preserve spelling", id: " Group / draft ", want: true},
+		{name: "empty", id: "", want: false},
+		{name: "blank", id: " \t", want: false},
+		{name: "missing namespace", id: "/draft", want: false},
+		{name: "missing local id", id: "group/", want: false},
+		{name: "multiple separators", id: "group/subgroup/draft", want: false},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			if got := validResourceID(test.id); got != test.want {
+				t.Fatalf("validResourceID(%q) = %t, want %t", test.id, got, test.want)
+			}
+		})
+	}
+}
+
+func TestValidResourceNamespace(t *testing.T) {
+	tests := []struct {
+		name      string
+		namespace string
+		want      bool
+	}{
+		{name: "ordinary", namespace: "group", want: true},
+		{name: "dotted", namespace: "group.v2", want: true},
+		{name: "preserved whitespace", namespace: " group ", want: true},
+		{name: "empty", namespace: "", want: false},
+		{name: "blank", namespace: " \t", want: false},
+		{name: "slash", namespace: "group/subgroup", want: false},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			if got := validResourceNamespace(test.namespace); got != test.want {
+				t.Fatalf("validResourceNamespace(%q) = %t, want %t", test.namespace, got, test.want)
+			}
+		})
+	}
+}
+
+func TestValidLocalResourceKey(t *testing.T) {
+	if !validLocalResourceKey("draft.v2") || !validLocalResourceKey(" draft ") {
+		t.Fatal("expected nonblank slash-free keys to be valid")
+	}
+	for _, key := range []string{"", " \t", "group/draft"} {
+		if validLocalResourceKey(key) {
+			t.Errorf("validLocalResourceKey(%q) = true, want false", key)
+		}
+	}
+}
+
+func TestQualifyResourceID(t *testing.T) {
+	tests := []struct {
+		name      string
+		id        string
+		namespace string
+		want      string
+		wantOK    bool
+	}{
+		{name: "without scope", id: "draft", want: "draft", wantOK: true},
+		{name: "with scope", id: "draft", namespace: "group", want: "group/draft", wantOK: true},
+		{name: "qualified bypass", id: "other/draft", namespace: "group", want: "other/draft", wantOK: true},
+		{name: "preserve spelling", id: " draft ", namespace: " Group ", want: " Group / draft ", wantOK: true},
+		{name: "omission remains caller policy", id: "", wantOK: false},
+		{name: "malformed ID", id: "group/draft/extra", namespace: "group", wantOK: false},
+		{name: "malformed scope", id: "draft", namespace: "group/subgroup", wantOK: false},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			got, ok := qualifyResourceID(test.id, test.namespace)
+			if got != test.want || ok != test.wantOK {
+				t.Fatalf("qualifyResourceID(%q, %q) = (%q, %t), want (%q, %t)", test.id, test.namespace, got, ok, test.want, test.wantOK)
+			}
+		})
+	}
+}
+
+func TestResourceNamespaceFromID(t *testing.T) {
+	tests := []struct {
+		name      string
+		id        string
+		namespace string
+		wantOK    bool
+	}{
+		{name: "qualified", id: "team/item", namespace: "team", wantOK: true},
+		{name: "same-prefix namespace stays distinct", id: "team-extra/item", namespace: "team-extra", wantOK: true},
+		{name: "unqualified", id: "item", wantOK: false},
+		{name: "malformed", id: "team/sub/item", wantOK: false},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			got, ok := resourceNamespaceFromID(test.id)
+			if got != test.namespace || ok != test.wantOK {
+				t.Fatalf("resourceNamespaceFromID(%q) = (%q, %t), want (%q, %t)", test.id, got, ok, test.namespace, test.wantOK)
+			}
+		})
+	}
+}

internal/domain/smoke_diagnostics.go

@@ -0,0 +1,263 @@
+package domain
+
+import (
+	"time"
+
+	"gitea.maximumdirect.net/eric/promptkit/internal/jsonvalue"
+)
+
+// BackendSmokeTestConfig describes optional backend-owned diagnostic defaults.
+type BackendSmokeTestConfig struct {
+	DefaultProfile *string
+	Reachability   *ReachabilityProbeConfig
+	Authentication *AuthenticationProbeConfig
+}
+
+// ReachabilityProbeConfig describes an optional endpoint for reachability tests.
+type ReachabilityProbeConfig struct {
+	Endpoint *string
+}
+
+// AuthenticationProbeConfig describes an optional authentication diagnostic.
+type AuthenticationProbeConfig struct {
+	Kind     *string
+	Endpoint *string
+}
+
+// SmokeTestKind identifies one built-in diagnostic operation.
+type SmokeTestKind string
+
+const (
+	SmokeTestReachability     SmokeTestKind = "reachability"
+	SmokeTestAuthentication   SmokeTestKind = "authentication"
+	SmokeTestTextInference    SmokeTestKind = "text_inference"
+	SmokeTestStructuredOutput SmokeTestKind = "structured_output"
+)
+
+// SmokeTestRequest selects one diagnostic and its execution target.
+type SmokeTestRequest struct {
+	Kind             SmokeTestKind
+	BackendID        string
+	PromptID         string
+	ProfileID        string
+	Execution        *ExecutionTargetOverride
+	APIKey           string `json:"-" yaml:"-"`
+	TransientRetries *int
+}
+
+// SmokeTestReport contains factual diagnostic results, not generated content.
+type SmokeTestReport struct {
+	Kind       SmokeTestKind
+	Supported  bool
+	Applicable *bool
+	Completed  bool
+	Reason     SmokeTestReason
+	Target     SmokeTestTarget
+	Facts      SmokeTestFacts
+	Timing     SmokeTestTiming
+	Attempts   []SmokeTestAttempt
+	Usage      ObservedTokenUsage
+	Failure    ExecutionFailureKind
+}
+
+// SmokeTestTarget identifies the selected diagnostic target and its settings.
+type SmokeTestTarget struct {
+	BackendID              string
+	ProfileID              string
+	PromptID               string
+	PromptVersion          *string
+	DefaultSourceBackendID string
+	SelectionSource        string
+	Endpoint               string
+	EffectiveSettings      ExecutionTarget
+	SettingsPresence       ExecutionTargetPresence
+}
+
+// SmokeTestFacts contains optional factual observations from a diagnostic.
+type SmokeTestFacts struct {
+	CredentialsSupplied       *bool
+	EndpointReachable         *bool
+	CredentialsAccepted       *bool
+	ResponseReceived          *bool
+	GenerationCompleted       *bool
+	TextReturned              *bool
+	ExpectedTextMatched       *bool
+	StructuredOutputRequested *bool
+	ValidJSON                 *bool
+	SchemaMatched             *bool
+}
+
+// SmokeTestTiming records elapsed diagnostic and phase durations.
+type SmokeTestTiming struct {
+	StartedAt          time.Time
+	Duration           time.Duration
+	CapacityWait       *time.Duration
+	RequestDuration    *time.Duration
+	RetryDelay         *time.Duration
+	EvaluationDuration *time.Duration
+}
+
+// SmokeTestAttempt records one dispatched attempt or an interrupted acquisition.
+type SmokeTestAttempt struct {
+	Dispatched      bool
+	InitialEndpoint string
+	Endpoint        string
+	HTTPStatus      *int
+	Facts           SmokeTestFacts
+	Timing          SmokeTestTiming
+	Failure         ExecutionFailureKind
+	Usage           ObservedTokenUsage
+}
+
+// SmokeTestReason identifies additional factual context for a diagnostic.
+type SmokeTestReason string
+
+const (
+	SmokeTestReasonNone                               SmokeTestReason = ""
+	SmokeTestReasonAuthenticationNotApplicable        SmokeTestReason = "authentication_not_applicable"
+	SmokeTestReasonProbeNotConfigured                 SmokeTestReason = "probe_not_configured"
+	SmokeTestReasonHTTPDiagnosticsUnavailable         SmokeTestReason = "http_diagnostics_unavailable"
+	SmokeTestReasonRequiredCredentialMissing          SmokeTestReason = "required_credential_missing"
+	SmokeTestReasonAuthenticationResponseUnrecognized SmokeTestReason = "authentication_response_unrecognized"
+)
+
+// CloneBackend returns a copy of a backend, including its mutable settings.
+func CloneBackend(backend Backend) (Backend, error) {
+	cloned := backend
+	var err error
+	cloned.ExtraParams, err = jsonvalue.CopyMap(backend.ExtraParams)
+	if err != nil {
+		return Backend{}, err
+	}
+	cloned.SmokeTests = CloneBackendSmokeTestConfig(backend.SmokeTests)
+	return cloned, nil
+}
+
+// CloneBackendSmokeTestConfig returns an independent copy of optional metadata.
+func CloneBackendSmokeTestConfig(config *BackendSmokeTestConfig) *BackendSmokeTestConfig {
+	if config == nil {
+		return nil
+	}
+	cloned := *config
+	cloned.DefaultProfile = cloneString(config.DefaultProfile)
+	if config.Reachability != nil {
+		reachability := *config.Reachability
+		reachability.Endpoint = cloneString(config.Reachability.Endpoint)
+		cloned.Reachability = &reachability
+	}
+	if config.Authentication != nil {
+		authentication := *config.Authentication
+		authentication.Kind = cloneString(config.Authentication.Kind)
+		authentication.Endpoint = cloneString(config.Authentication.Endpoint)
+		cloned.Authentication = &authentication
+	}
+	return &cloned
+}
+
+// CloneSmokeTestRequest returns a copy that owns its optional settings.
+func CloneSmokeTestRequest(request SmokeTestRequest) (SmokeTestRequest, error) {
+	cloned := request
+	cloned.TransientRetries = cloneInt(request.TransientRetries)
+	if request.Execution == nil {
+		return cloned, nil
+	}
+	execution := *request.Execution
+	execution.Temperature = cloneFloat64(request.Execution.Temperature)
+	execution.MaxTokens = cloneInt(request.Execution.MaxTokens)
+	execution.TopP = cloneFloat64(request.Execution.TopP)
+	execution.TimeoutSeconds = cloneInt(request.Execution.TimeoutSeconds)
+	execution.ReasoningEffort = cloneString(request.Execution.ReasoningEffort)
+	var err error
+	execution.ExtraParams, err = jsonvalue.CopyMap(request.Execution.ExtraParams)
+	if err != nil {
+		return SmokeTestRequest{}, err
+	}
+	cloned.Execution = &execution
+	return cloned, nil
+}
+
+// CloneSmokeTestReport returns a copy with independent optional facts and maps.
+func CloneSmokeTestReport(report SmokeTestReport) (SmokeTestReport, error) {
+	cloned := report
+	cloned.Applicable = cloneBool(report.Applicable)
+	cloned.Target.PromptVersion = cloneString(report.Target.PromptVersion)
+	cloned.Facts = cloneSmokeTestFacts(report.Facts)
+	cloned.Timing = cloneSmokeTestTiming(report.Timing)
+	var err error
+	cloned.Target.EffectiveSettings.ExtraParams, err = jsonvalue.CopyMap(report.Target.EffectiveSettings.ExtraParams)
+	if err != nil {
+		return SmokeTestReport{}, err
+	}
+	if report.Attempts != nil {
+		cloned.Attempts = make([]SmokeTestAttempt, len(report.Attempts))
+		for index, attempt := range report.Attempts {
+			cloned.Attempts[index] = attempt
+			cloned.Attempts[index].HTTPStatus = cloneInt(attempt.HTTPStatus)
+			cloned.Attempts[index].Facts = cloneSmokeTestFacts(attempt.Facts)
+			cloned.Attempts[index].Timing = cloneSmokeTestTiming(attempt.Timing)
+		}
+	}
+	return cloned, nil
+}
+
+func cloneSmokeTestFacts(facts SmokeTestFacts) SmokeTestFacts {
+	facts.CredentialsSupplied = cloneBool(facts.CredentialsSupplied)
+	facts.EndpointReachable = cloneBool(facts.EndpointReachable)
+	facts.CredentialsAccepted = cloneBool(facts.CredentialsAccepted)
+	facts.ResponseReceived = cloneBool(facts.ResponseReceived)
+	facts.GenerationCompleted = cloneBool(facts.GenerationCompleted)
+	facts.TextReturned = cloneBool(facts.TextReturned)
+	facts.ExpectedTextMatched = cloneBool(facts.ExpectedTextMatched)
+	facts.StructuredOutputRequested = cloneBool(facts.StructuredOutputRequested)
+	facts.ValidJSON = cloneBool(facts.ValidJSON)
+	facts.SchemaMatched = cloneBool(facts.SchemaMatched)
+	return facts
+}
+
+func cloneSmokeTestTiming(timing SmokeTestTiming) SmokeTestTiming {
+	timing.CapacityWait = cloneDuration(timing.CapacityWait)
+	timing.RequestDuration = cloneDuration(timing.RequestDuration)
+	timing.RetryDelay = cloneDuration(timing.RetryDelay)
+	timing.EvaluationDuration = cloneDuration(timing.EvaluationDuration)
+	return timing
+}
+
+func cloneBool(value *bool) *bool {
+	if value == nil {
+		return nil
+	}
+	cloned := *value
+	return &cloned
+}
+
+func cloneDuration(value *time.Duration) *time.Duration {
+	if value == nil {
+		return nil
+	}
+	cloned := *value
+	return &cloned
+}
+
+func cloneFloat64(value *float64) *float64 {
+	if value == nil {
+		return nil
+	}
+	cloned := *value
+	return &cloned
+}
+
+func cloneInt(value *int) *int {
+	if value == nil {
+		return nil
+	}
+	cloned := *value
+	return &cloned
+}
+
+func cloneString(value *string) *string {
+	if value == nil {
+		return nil
+	}
+	cloned := *value
+	return &cloned
+}

internal/domain/smoke_diagnostics_test.go

@@ -0,0 +1,115 @@
+package domain
+
+import (
+	"testing"
+	"time"
+)
+
+func TestCloneBackendCopiesDiagnosticMetadataAndProviderValues(t *testing.T) {
+	profile := "profile"
+	reachabilityEndpoint := "https://probe.example/health"
+	authKind := "openrouter_key"
+	authEndpoint := "https://probe.example/key"
+	backend := Backend{
+		ExtraParams: map[string]any{"nested": map[string]any{"value": "original"}},
+		SmokeTests: &BackendSmokeTestConfig{
+			DefaultProfile: &profile,
+			Reachability:   &ReachabilityProbeConfig{Endpoint: &reachabilityEndpoint},
+			Authentication: &AuthenticationProbeConfig{
+				Kind:     &authKind,
+				Endpoint: &authEndpoint,
+			},
+		},
+	}
+
+	cloned, err := CloneBackend(backend)
+	if err != nil {
+		t.Fatal(err)
+	}
+	*cloned.SmokeTests.DefaultProfile = "changed"
+	*cloned.SmokeTests.Reachability.Endpoint = "changed"
+	*cloned.SmokeTests.Authentication.Kind = "changed"
+	*cloned.SmokeTests.Authentication.Endpoint = "changed"
+	cloned.ExtraParams["nested"].(map[string]any)["value"] = "changed"
+
+	if profile != "profile" || reachabilityEndpoint != "https://probe.example/health" ||
+		authKind != "openrouter_key" || authEndpoint != "https://probe.example/key" {
+		t.Fatal("cloned diagnostic metadata shared source pointers")
+	}
+	if got := backend.ExtraParams["nested"].(map[string]any)["value"]; got != "original" {
+		t.Fatalf("source provider parameter changed through clone: %v", got)
+	}
+}
+
+func TestCloneSmokeTestRequestOwnsOptionalSettings(t *testing.T) {
+	temperature := 0.25
+	retries := 2
+	reasoning := "low"
+	request := SmokeTestRequest{
+		APIKey:           "secret",
+		TransientRetries: &retries,
+		Execution: &ExecutionTargetOverride{
+			Temperature:     &temperature,
+			ReasoningEffort: &reasoning,
+			ExtraParams:     map[string]any{"nested": map[string]any{"value": "original"}},
+		},
+	}
+
+	cloned, err := CloneSmokeTestRequest(request)
+	if err != nil {
+		t.Fatal(err)
+	}
+	*cloned.TransientRetries = 3
+	*cloned.Execution.Temperature = 0.5
+	*cloned.Execution.ReasoningEffort = "high"
+	cloned.Execution.ExtraParams["nested"].(map[string]any)["value"] = "changed"
+
+	if retries != 2 || temperature != 0.25 || reasoning != "low" {
+		t.Fatal("cloned request shared optional scalar pointers")
+	}
+	if got := request.Execution.ExtraParams["nested"].(map[string]any)["value"]; got != "original" {
+		t.Fatalf("source provider parameter changed through clone: %v", got)
+	}
+}
+
+func TestCloneSmokeTestReportOwnsMutableValues(t *testing.T) {
+	applicable := true
+	reachable := true
+	status := 200
+	wait := 3 * time.Millisecond
+	promptVersion := "v1"
+	report := SmokeTestReport{
+		Applicable: &applicable,
+		Target: SmokeTestTarget{
+			PromptVersion: &promptVersion,
+			EffectiveSettings: ExecutionTarget{
+				ExtraParams: map[string]any{"nested": map[string]any{"value": "original"}},
+			},
+		},
+		Facts: SmokeTestFacts{EndpointReachable: &reachable},
+		Attempts: []SmokeTestAttempt{{
+			HTTPStatus: &status,
+			Facts:      SmokeTestFacts{EndpointReachable: &reachable},
+			Timing:     SmokeTestTiming{CapacityWait: &wait},
+		}},
+	}
+
+	cloned, err := CloneSmokeTestReport(report)
+	if err != nil {
+		t.Fatal(err)
+	}
+	*cloned.Applicable = false
+	*cloned.Facts.EndpointReachable = false
+	*cloned.Attempts[0].HTTPStatus = 503
+	*cloned.Attempts[0].Facts.EndpointReachable = false
+	*cloned.Attempts[0].Timing.CapacityWait = time.Second
+	*cloned.Target.PromptVersion = "changed"
+	cloned.Target.EffectiveSettings.ExtraParams["nested"].(map[string]any)["value"] = "changed"
+
+	if !applicable || !reachable || status != 200 || wait != 3*time.Millisecond || promptVersion != "v1" {
+		t.Fatal("cloned report shared optional scalar pointers")
+	}
+	if got := report.Target.EffectiveSettings.ExtraParams["nested"].(map[string]any)["value"]; got != "original" {
+		t.Fatalf("source provider parameter changed through clone: %v", got)
+	}
+}

internal/engine/engine.go

@@ -14,7 +14,6 @@ import (
 	"gitea.maximumdirect.net/eric/ConfigKit"
 	"gitea.maximumdirect.net/eric/promptkit/internal/artifact"
 	"gitea.maximumdirect.net/eric/promptkit/internal/capacity"
-	"gitea.maximumdirect.net/eric/promptkit/internal/catalog"
 	"gitea.maximumdirect.net/eric/promptkit/internal/configuration"
 	"gitea.maximumdirect.net/eric/promptkit/internal/defaults"
 	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
@@ -81,8 +80,41 @@ func (o *Options) SetSchemaFile(path string) error {
 
 // Engine forwards domain operations to the single assembled use-case runner.
 type Engine struct {
-	runner     *usecase.Runner
-	inspection configuration.Inspection
+	runner      *usecase.Runner
+	smokeTester *usecase.SmokeTester
+	inspection  configuration.Inspection
+	listing     identityInventory
+	namespaces  resourceNamespaces
+}
+
+type resourceNamespaces struct {
+	prompt  string
+	profile string
+	backend string
+}
+
+type identityInventory interface {
+	ListBackends(context.Context) ([]string, error)
+	ListProfiles(context.Context) ([]string, error)
+	ListPrompts(context.Context) ([]domain.PromptIdentity, error)
+	ListNamespaces(context.Context, []string) ([]string, error)
+	ListCollections(context.Context) ([]configuration.CollectionIdentity, error)
+}
+
+// ListingFilterMode selects namespace membership for one identity listing.
+type ListingFilterMode uint8
+
+const (
+	ListingDefault ListingFilterMode = iota
+	ListingNamed
+	ListingUnqualified
+	ListingAll
+)
+
+// ListingFilter optionally overrides the namespace selected by an engine view.
+type ListingFilter struct {
+	Mode ListingFilterMode
+	Name string
 }
 
 // New assembles an engine from facade-selected configuration and collaborators.
@@ -91,11 +123,7 @@ func New(cfg Config, options Options) (*Engine, error) {
 	if err != nil {
 		return nil, err
 	}
-	underlays, err := catalog.Underlays()
-	if err != nil {
-		return nil, fmt.Errorf("select maintained configuration: %w", err)
-	}
-	underlays = append(underlays, cfg.Sources.Underlays...)
+	underlays := cfg.Sources.Underlays
 	main := configkit.Input{Source: configkit.NoSource()}
 	if cfg.Sources.Main != nil {
 		main = *cfg.Sources.Main
@@ -118,11 +146,13 @@ func New(cfg Config, options Options) (*Engine, error) {
 		validator = validate.NewStandardValidator(schemaDir)
 	}
 	var client llm.Client
+	var diagnosticHTTPClient *llm.OpenAICompatibleClient
 	if options.llmClient == nil {
 		builtIn, newErr := llm.NewOpenAICompatibleClient(llm.OpenAICompatibleConfig{Timeout: cfg.Timeout, HTTPClient: cfg.HTTPClient})
 		if newErr != nil {
 			return nil, newErr
 		}
+		diagnosticHTTPClient = builtIn
 		client = generation.NewBuiltIn(manager, builtIn)
 	} else {
 		client = generation.NewInjected(manager, options.llmClient)
@@ -132,12 +162,25 @@ func New(cfg Config, options Options) (*Engine, error) {
 		reader = artifact.NewCompositeReader()
 	}
 
+	runner := usecase.NewRunnerWithRepairer(snapshot, snapshot, reader, prompt.NewCompiledRenderer(snapshot), client, validator, usecase.NewDefaultOutputRepairer(client), manager, defaultRetries)
 	return &Engine{
-		runner:     usecase.NewRunnerWithRepairer(snapshot, snapshot, reader, prompt.NewCompiledRenderer(snapshot), client, validator, usecase.NewDefaultOutputRepairer(client), manager, defaultRetries),
-		inspection: snapshot.Inspection(),
+		runner:      runner,
+		smokeTester: usecase.NewSmokeTester(runner, diagnosticHTTPClient),
+		inspection:  snapshot.Inspection(),
+		listing:     snapshot,
 	}, nil
 }
 
+// WithNamespaces returns an immutable view sharing this engine's assembled
+// collaborators and configuration snapshot. Caller-supplied selection IDs are
+// qualified at each operation boundary; captured configuration references are
+// not rewritten.
+func (e *Engine) WithNamespaces(prompt, profile, backend string) *Engine {
+	view := *e
+	view.namespaces = resourceNamespaces{prompt: prompt, profile: profile, backend: backend}
+	return &view
+}
+
 // InspectConfiguration returns read-only operations over the captured result.
 func (e *Engine) InspectConfiguration() configuration.Inspection {
 	if e == nil {
@@ -175,21 +218,213 @@ func fileSource(name string) (fs.FS, string, string, error) {
 	return os.DirFS(directory), filepath.ToSlash(base), directory, nil
 }
 
-func (e *Engine) InspectPrompt(ctx context.Context, id, version string) (*domain.PromptInspection, error) {
-	return e.runner.InspectPrompt(ctx, id, version)
+func (e *Engine) InspectPrompt(ctx context.Context, id string) (*domain.PromptInspection, error) {
+	var err error
+	id, err = e.qualifyResourceID(id, e.namespaces.prompt, "prompt")
+	if err != nil {
+		return nil, err
+	}
+	return e.runner.InspectPrompt(ctx, id)
+}
+func (e *Engine) InspectRequirements(
+	ctx context.Context,
+	request usecase.RequirementInspectionRequest,
+) (*domain.RequirementInspection, error) {
+	var err error
+	request.PromptID, err = e.qualifyResourceID(request.PromptID, e.namespaces.prompt, "prompt")
+	if err != nil {
+		return nil, err
+	}
+	request.ProfileID, err = e.qualifyResourceID(request.ProfileID, e.namespaces.profile, "profile")
+	if err != nil {
+		return nil, err
+	}
+	return e.runner.InspectRequirements(ctx, request)
 }
 func (e *Engine) InspectProfile(ctx context.Context, id string) (*domain.ProfileInspection, error) {
+	var err error
+	id, err = e.qualifyResourceID(id, e.namespaces.profile, "profile")
+	if err != nil {
+		return nil, err
+	}
 	return e.runner.InspectProfile(ctx, id)
 }
+
+func (e *Engine) ListBackends(ctx context.Context, filters ...ListingFilter) ([]string, error) {
+	return filterIdentityList(ctx, filters, e.namespaces.backend, e.listing.ListBackends)
+}
+
+func (e *Engine) ListProfiles(ctx context.Context, filters ...ListingFilter) ([]string, error) {
+	return filterIdentityList(ctx, filters, e.namespaces.profile, e.listing.ListProfiles)
+}
+
+func (e *Engine) ListPrompts(ctx context.Context, filters ...ListingFilter) ([]domain.PromptIdentity, error) {
+	mode, namespace, err := resolveListingFilter(filters, e.namespaces.prompt)
+	if err != nil {
+		return nil, err
+	}
+	prompts, err := e.listing.ListPrompts(ctx)
+	if err != nil {
+		return nil, err
+	}
+	var filtered []domain.PromptIdentity
+	for _, prompt := range prompts {
+		if matchesListingNamespace(prompt.ID, mode, namespace) {
+			filtered = append(filtered, prompt)
+		}
+	}
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	return filtered, nil
+}
+
+func (e *Engine) ListNamespaces(ctx context.Context, kinds []string) ([]string, error) {
+	for _, kind := range kinds {
+		switch kind {
+		case "prompt", "profile", "backend":
+		default:
+			return nil, fmt.Errorf("%w: unknown resource kind %q", usecase.ErrInvalidRequest, kind)
+		}
+	}
+	return e.listing.ListNamespaces(ctx, kinds)
+}
+
+func (e *Engine) ListCollections(ctx context.Context) ([]configuration.CollectionIdentity, error) {
+	return e.listing.ListCollections(ctx)
+}
+
+func filterIdentityList(
+	ctx context.Context,
+	filters []ListingFilter,
+	scope string,
+	list func(context.Context) ([]string, error),
+) ([]string, error) {
+	mode, namespace, err := resolveListingFilter(filters, scope)
+	if err != nil {
+		return nil, err
+	}
+	ids, err := list(ctx)
+	if err != nil {
+		return nil, err
+	}
+	var filtered []string
+	for _, id := range ids {
+		if matchesListingNamespace(id, mode, namespace) {
+			filtered = append(filtered, id)
+		}
+	}
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	return filtered, nil
+}
+
+func resolveListingFilter(filters []ListingFilter, scope string) (ListingFilterMode, string, error) {
+	if len(filters) > 1 {
+		return 0, "", fmt.Errorf("%w: at most one listing filter is allowed", usecase.ErrInvalidRequest)
+	}
+	filter := ListingFilter{}
+	if len(filters) == 1 {
+		filter = filters[0]
+	}
+	switch filter.Mode {
+	case ListingDefault:
+		if scope == "" {
+			return ListingAll, "", nil
+		}
+		return ListingNamed, scope, nil
+	case ListingNamed:
+		if !domain.IsValidResourceNamespace(filter.Name) {
+			return 0, "", fmt.Errorf("%w: invalid listing namespace", usecase.ErrInvalidRequest)
+		}
+		return ListingNamed, filter.Name, nil
+	case ListingUnqualified, ListingAll:
+		return filter.Mode, "", nil
+	default:
+		return 0, "", fmt.Errorf("%w: unknown listing filter mode", usecase.ErrInvalidRequest)
+	}
+}
+
+func matchesListingNamespace(id string, mode ListingFilterMode, namespace string) bool {
+	switch mode {
+	case ListingNamed:
+		idNamespace, _, qualified := strings.Cut(id, "/")
+		return qualified && idNamespace == namespace
+	case ListingUnqualified:
+		return !strings.Contains(id, "/")
+	case ListingAll:
+		return true
+	default:
+		return false
+	}
+}
 func (e *Engine) Prepare(ctx context.Context, request domain.RunRequest) (*domain.PreparedRun, error) {
+	request, err := e.qualifyRunRequest(request)
+	if err != nil {
+		return nil, err
+	}
 	return e.runner.Prepare(ctx, request)
 }
 func (e *Engine) PrepareExecution(ctx context.Context, request domain.RunRequest) (*usecase.PreparedExecution, error) {
+	request, err := e.qualifyRunRequest(request)
+	if err != nil {
+		return nil, err
+	}
 	return e.runner.PrepareExecution(ctx, request)
 }
 func (e *Engine) Run(ctx context.Context, request domain.RunRequest) (*domain.RunResult, error) {
+	request, err := e.qualifyRunRequest(request)
+	if err != nil {
+		return nil, err
+	}
 	return e.runner.Run(ctx, request)
 }
+
+func (e *Engine) qualifyRunRequest(request domain.RunRequest) (domain.RunRequest, error) {
+	var err error
+	request.PromptID, err = e.qualifyResourceID(request.PromptID, e.namespaces.prompt, "prompt")
+	if err != nil {
+		return domain.RunRequest{}, err
+	}
+	request.ProfileID, err = e.qualifyResourceID(request.ProfileID, e.namespaces.profile, "profile")
+	if err != nil {
+		return domain.RunRequest{}, err
+	}
+	return request, nil
+}
+
+func (e *Engine) qualifyResourceID(id, namespace, kind string) (string, error) {
+	if id == "" {
+		return "", nil
+	}
+	qualified, ok := domain.QualifyResourceID(id, namespace)
+	if !ok {
+		return "", fmt.Errorf("%w: invalid %s ID", usecase.ErrInvalidRequest, kind)
+	}
+	return qualified, nil
+}
+
 func (e *Engine) RunPrepared(ctx context.Context, prepared *usecase.PreparedExecution) (*domain.RunResult, error) {
 	return e.runner.RunPrepared(ctx, prepared)
 }
+
+func (e *Engine) SmokeTest(ctx context.Context, request domain.SmokeTestRequest) (*domain.SmokeTestReport, error) {
+	if e == nil || e.smokeTester == nil {
+		return nil, fmt.Errorf("%w: smoke tester is not configured", usecase.ErrInvalidRequest)
+	}
+	var err error
+	request.PromptID, err = e.qualifyResourceID(request.PromptID, e.namespaces.prompt, "prompt")
+	if err != nil {
+		return nil, err
+	}
+	request.ProfileID, err = e.qualifyResourceID(request.ProfileID, e.namespaces.profile, "profile")
+	if err != nil {
+		return nil, err
+	}
+	request.BackendID, err = e.qualifyResourceID(request.BackendID, e.namespaces.backend, "backend")
+	if err != nil {
+		return nil, err
+	}
+	return e.smokeTester.Run(ctx, request)
+}

internal/engine/smoke_test.go

@@ -0,0 +1,124 @@
+package engine
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"strings"
+	"testing"
+
+	"gitea.maximumdirect.net/eric/ConfigKit"
+	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
+)
+
+func engineSmokeBackendInput() configkit.Input {
+	return configkit.Input{Source: configkit.Mapping("smoke-test backend", map[string]any{
+		"backends": map[string]any{"test-backend": map[string]any{
+			"endpoint": "https://test-backend.example/v1",
+			"smoke_tests": map[string]any{
+				"default_profile": "test-profile",
+				"authentication":  map[string]any{"kind": "none"},
+			},
+		}},
+		"profiles": map[string]any{"test-profile": map[string]any{
+			"backend": "test-backend",
+			"model":   "synthetic-model",
+		}},
+	})}
+}
+
+func TestEngineSmokeTestUsesInjectedGenerationWithoutHTTPSupport(t *testing.T) {
+	calls := 0
+	options := Options{}
+	options.SetLLMClient(engineSmokeClientFunc(func(_ context.Context, request domain.GenerateRequest) (*domain.GenerateResponse, error) {
+		calls++
+		if len(request.Prompt.Messages) != 1 || request.Prompt.Messages[0].Role != "user" {
+			t.Fatalf("injected generation request = %+v", request)
+		}
+		return &domain.GenerateResponse{Content: "engine response"}, nil
+	}))
+	input := engineSmokeBackendInput()
+	assembled, err := New(Config{Sources: ConfigurationSources{Main: &input}}, options)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	report, err := assembled.SmokeTest(context.Background(), domain.SmokeTestRequest{
+		Kind: domain.SmokeTestTextInference, BackendID: "test-backend",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if calls != 1 || !report.Completed || !report.Supported || report.Applicable == nil || !*report.Applicable ||
+		report.Facts.GenerationCompleted == nil || !*report.Facts.GenerationCompleted ||
+		report.Facts.TextReturned == nil || !*report.Facts.TextReturned ||
+		report.Facts.ExpectedTextMatched == nil || *report.Facts.ExpectedTextMatched ||
+		report.Facts.EndpointReachable != nil || report.Target.BackendID != "test-backend" {
+		t.Fatalf("injected smoke report calls=%d: %+v", calls, report)
+	}
+	if report.Target.Endpoint != "" || report.Target.EffectiveSettings.Endpoint == "" || len(report.Attempts) != 1 ||
+		report.Attempts[0].InitialEndpoint != "" || report.Attempts[0].Endpoint != "" {
+		t.Fatalf("injected report claimed HTTP destinations: %+v", report)
+	}
+
+	authentication, err := assembled.SmokeTest(context.Background(), domain.SmokeTestRequest{
+		Kind: domain.SmokeTestAuthentication, BackendID: "test-backend",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !authentication.Supported || authentication.Applicable == nil || *authentication.Applicable ||
+		authentication.Reason != domain.SmokeTestReasonAuthenticationNotApplicable || len(authentication.Attempts) != 0 {
+		t.Fatalf("injected authentication report = %+v", authentication)
+	}
+}
+
+func TestEngineSmokeTestUsesBuiltInHTTPClientForInferenceEvidence(t *testing.T) {
+	var observedURL string
+	var authorization string
+	options := Options{}
+	input := engineSmokeBackendInput()
+	assembled, err := New(Config{Sources: ConfigurationSources{Main: &input}, HTTPClient: &http.Client{Transport: engineRoundTripperFunc(func(request *http.Request) (*http.Response, error) {
+		observedURL = request.URL.String()
+		authorization = request.Header.Get("Authorization")
+		return &http.Response{
+			StatusCode: http.StatusOK,
+			Header:     make(http.Header),
+			Body:       io.NopCloser(strings.NewReader(`{"choices":[{"message":{"content":"engine response"}}],"usage":{"prompt_tokens":1,"completion_tokens":1,"total_tokens":2}}`)),
+		}, nil
+	})}}, options)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	report, err := assembled.SmokeTest(context.Background(), domain.SmokeTestRequest{
+		Kind: domain.SmokeTestTextInference, BackendID: "test-backend",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if observedURL == "" || authorization != "" {
+		t.Fatalf("built-in request URL=%q authorization=%q", observedURL, authorization)
+	}
+	if !report.Completed || report.Facts.EndpointReachable == nil || !*report.Facts.EndpointReachable ||
+		report.Facts.ResponseReceived == nil || !*report.Facts.ResponseReceived ||
+		report.Facts.GenerationCompleted == nil || !*report.Facts.GenerationCompleted ||
+		report.Facts.CredentialsSupplied == nil || *report.Facts.CredentialsSupplied ||
+		report.Facts.TextReturned == nil || !*report.Facts.TextReturned ||
+		report.Facts.ExpectedTextMatched == nil || *report.Facts.ExpectedTextMatched || len(report.Attempts) != 1 ||
+		report.Attempts[0].Endpoint != observedURL {
+		t.Fatalf("built-in smoke report = %+v", report)
+	}
+}
+
+type engineSmokeClientFunc func(context.Context, domain.GenerateRequest) (*domain.GenerateResponse, error)
+
+func (f engineSmokeClientFunc) Generate(ctx context.Context, request domain.GenerateRequest) (*domain.GenerateResponse, error) {
+	return f(ctx, request)
+}
+
+type engineRoundTripperFunc func(*http.Request) (*http.Response, error)
+
+func (f engineRoundTripperFunc) RoundTrip(request *http.Request) (*http.Response, error) {
+	return f(request)
+}

internal/generation/coordinator.go

@@ -72,14 +72,43 @@ func (e *ExhaustedError) Attempts() uint64 {
 // Generate executes either one opaque client call or a frozen built-in HTTP
 // sequence with one permit per actual dispatch.
 func (c *Coordinator) Generate(ctx context.Context, req domain.GenerateRequest) (*domain.GenerateResponse, error) {
+	response, err, _ := c.generate(ctx, req, false)
+	return response, err
+}
+
+// GenerateWithEvidence runs the built-in retry path and returns its factual
+// attempt evidence alongside any response retained before cancellation.
+func (c *Coordinator) GenerateWithEvidence(
+	ctx context.Context,
+	req domain.GenerateRequest,
+) (*domain.GenerateResponse, error, GenerationEvidence) {
+	return c.generate(ctx, req, true)
+}
+
+func (c *Coordinator) generate(
+	ctx context.Context,
+	req domain.GenerateRequest,
+	captureEvidence bool,
+) (*domain.GenerateResponse, error, GenerationEvidence) {
 	if c.injected != nil {
-		return c.generateInjected(ctx, req)
+		return c.generateInjected(ctx, req, captureEvidence)
 	}
 	prepared, err := c.builtIn.PrepareGeneration(req)
 	if err != nil {
-		return nil, err
+		return nil, err, GenerationEvidence{}
 	}
 
+	evidence := GenerationEvidence{}
+	if captureEvidence {
+		evidence.InitialEndpoint = prepared.InitialEndpoint()
+	}
+	var usage observation.UsageAccumulator
+	finish := func(response *domain.GenerateResponse, err error) (*domain.GenerateResponse, error, GenerationEvidence) {
+		if captureEvidence {
+			evidence.Usage = usage.Observed()
+		}
+		return response, err, evidence
+	}
 	var attempts, retriesUsed uint64
 	recorder := observation.FromContext(ctx)
 	generation := req.Generation
@@ -88,56 +117,102 @@ func (c *Coordinator) Generate(ctx context.Context, req domain.GenerateRequest)
 	}
 	for {
 		if err := ctx.Err(); err != nil {
-			return nil, err
+			return finish(nil, err)
 		}
 		ordinal := attempts + 1
-		outcome, dispatched, capacityWait, generationDuration := c.execute(ctx, req.Target.BackendID, prepared)
+		outcome, dispatched, capacityWait, generationDuration, startedAt := c.execute(ctx, req.Target.BackendID, prepared, captureEvidence)
 		if dispatched {
 			attempts++
 		}
+		if captureEvidence {
+			attempt := AttemptEvidence{
+				StartedAt:           startedAt.UTC(),
+				Dispatched:          dispatched,
+				ResponseReceived:    outcome.Evidence.ResponseReceived,
+				HTTP:                cloneHTTPEvidence(outcome.Evidence),
+				CapacityWait:        capacityWait,
+				RequestDuration:     generationDuration,
+				Failure:             ClassifyFailure(outcome.Err),
+				ResponseDecoded:     outcome.ResponseDecoded,
+				GenerationCompleted: outcome.GenerationCompleted,
+			}
+			if outcome.StructuredOutputRequested != nil {
+				requested := *outcome.StructuredOutputRequested
+				attempt.StructuredOutputRequested = &requested
+			}
+			if dispatched {
+				usage.Add(outcome.Usage, outcome.UsagePresence)
+				var attemptUsage observation.UsageAccumulator
+				attemptUsage.Add(outcome.Usage, outcome.UsagePresence)
+				attempt.Usage = attemptUsage.Observed()
+			}
+			evidence.Attempts = append(evidence.Attempts, attempt)
+		}
 		if recorder != nil {
 			recorder.Attempt(observation.AttemptData{Generation: generation, Attempt: ordinal,
 				Dispatched: dispatched, CapacityWait: capacityWait, GenerationDuration: generationDuration,
-				Outcome: attemptOutcome(outcome.Err), Failure: attemptFailure(outcome.Err),
+				Outcome: attemptOutcome(outcome.Err), Failure: ClassifyFailure(outcome.Err),
 				StatusCode: outcome.StatusCode, Usage: outcome.Usage, UsagePresence: outcome.UsagePresence})
 		}
 		if outcome.Err == nil {
 			if err := ctx.Err(); err != nil {
-				return nil, err
+				if captureEvidence {
+					return finish(outcome.Response, err)
+				}
+				return finish(nil, err)
 			}
-			return outcome.Response, nil
+			return finish(outcome.Response, nil)
 		}
 		if !dispatched || !eligibleStatus(outcome) {
-			return nil, outcome.Err
+			if captureEvidence {
+				return finish(outcome.Response, outcome.Err)
+			}
+			return finish(nil, outcome.Err)
 		}
 		if retriesUsed == req.TransientRetries {
 			if retriesUsed == 0 {
-				return nil, outcome.Err
+				return finish(nil, outcome.Err)
 			}
-			return nil, &ExhaustedError{attempts: attempts, cause: outcome.Err}
+			return finish(nil, &ExhaustedError{attempts: attempts, cause: outcome.Err})
 		}
 		if err := ctx.Err(); err != nil {
-			return nil, err
+			return finish(nil, err)
 		}
 		retryOrdinal := retriesUsed + 1
 		delay := retryDelay(c.backoff(retryOrdinal), outcome.RetryNotBefore, c.now())
 		waitStart := c.now()
 		waitErr := c.wait(ctx, delay)
+		waitDuration := elapsed(waitStart, c.now())
+		if captureEvidence {
+			evidence.RetryDelays = append(evidence.RetryDelays, waitDuration)
+		}
 		if recorder != nil {
 			recorder.Delay(observation.DelayData{Generation: generation, Attempt: attempts,
-				Elapsed: elapsed(waitStart, c.now()), Failure: attemptFailure(waitErr)})
+				Elapsed: waitDuration, Failure: ClassifyFailure(waitErr)})
 		}
 		if waitErr != nil {
-			return nil, waitErr
+			return finish(nil, waitErr)
 		}
 		if err := ctx.Err(); err != nil {
-			return nil, err
+			return finish(nil, err)
 		}
 		retriesUsed++
 	}
 }
 
-func (c *Coordinator) generateInjected(ctx context.Context, req domain.GenerateRequest) (*domain.GenerateResponse, error) {
+func (c *Coordinator) generateInjected(
+	ctx context.Context,
+	req domain.GenerateRequest,
+	captureEvidence bool,
+) (*domain.GenerateResponse, error, GenerationEvidence) {
+	evidence := GenerationEvidence{}
+	var usage observation.UsageAccumulator
+	finish := func(response *domain.GenerateResponse, err error) (*domain.GenerateResponse, error, GenerationEvidence) {
+		if captureEvidence {
+			evidence.Usage = usage.Observed()
+		}
+		return response, err, evidence
+	}
 	recorder := observation.FromContext(ctx)
 	generation := req.Generation
 	if generation == 0 {
@@ -147,18 +222,32 @@ func (c *Coordinator) generateInjected(ctx context.Context, req domain.GenerateR
 	release, err := c.manager.Acquire(ctx, req.Target.BackendID)
 	capacityWait := c.capacityWait(req.Target.BackendID, start)
 	if err != nil {
-		if recorder != nil {
-			recorder.Attempt(observation.AttemptData{Generation: generation, Attempt: 1, CapacityWait: capacityWait, Outcome: domain.ExecutionOutcomeError, Failure: attemptFailure(err)})
+		if captureEvidence {
+			evidence.Attempts = append(evidence.Attempts, AttemptEvidence{
+				StartedAt:    start.UTC(),
+				CapacityWait: capacityWait,
+				Failure:      ClassifyFailure(err),
+			})
 		}
-		return nil, err
+		if recorder != nil {
+			recorder.Attempt(observation.AttemptData{Generation: generation, Attempt: 1, CapacityWait: capacityWait, Outcome: domain.ExecutionOutcomeError, Failure: ClassifyFailure(err)})
+		}
+		return finish(nil, err)
 	}
 	defer release()
 	if err := ctx.Err(); err != nil {
 		release()
-		if recorder != nil {
-			recorder.Attempt(observation.AttemptData{Generation: generation, Attempt: 1, CapacityWait: capacityWait, Outcome: domain.ExecutionOutcomeError, Failure: attemptFailure(err)})
+		if captureEvidence {
+			evidence.Attempts = append(evidence.Attempts, AttemptEvidence{
+				StartedAt:    start.UTC(),
+				CapacityWait: capacityWait,
+				Failure:      ClassifyFailure(err),
+			})
 		}
-		return nil, err
+		if recorder != nil {
+			recorder.Attempt(observation.AttemptData{Generation: generation, Attempt: 1, CapacityWait: capacityWait, Outcome: domain.ExecutionOutcomeError, Failure: ClassifyFailure(err)})
+		}
+		return finish(nil, err)
 	}
 	dispatchStart := c.now()
 	response, err := c.injected.Generate(ctx, req)
@@ -166,10 +255,33 @@ func (c *Coordinator) generateInjected(ctx context.Context, req domain.GenerateR
 	if err == nil && response == nil {
 		err = llm.ErrMalformedResponse
 	}
+	if captureEvidence {
+		attempt := AttemptEvidence{
+			StartedAt:           start.UTC(),
+			Dispatched:          true,
+			ResponseReceived:    response != nil,
+			RequestDuration:     duration,
+			Failure:             ClassifyFailure(err),
+			GenerationCompleted: err == nil && response != nil,
+		}
+		requested := req.StructuredOutput != nil
+		attempt.StructuredOutputRequested = &requested
+		var reportedUsage domain.TokenUsage
+		var reportedPresence *domain.TokenUsagePresence
+		if err == nil && response != nil {
+			reportedUsage = response.Usage
+			reportedPresence = response.UsagePresence
+		}
+		usage.Add(reportedUsage, reportedPresence)
+		var attemptUsage observation.UsageAccumulator
+		attemptUsage.Add(reportedUsage, reportedPresence)
+		attempt.Usage = attemptUsage.Observed()
+		evidence.Attempts = append(evidence.Attempts, attempt)
+	}
 	release()
 	if recorder != nil {
 		data := observation.AttemptData{Generation: generation, Attempt: 1, Dispatched: true, CapacityWait: capacityWait, GenerationDuration: duration,
-			Outcome: attemptOutcome(err), Failure: attemptFailure(err)}
+			Outcome: attemptOutcome(err), Failure: ClassifyFailure(err)}
 		if err == nil {
 			data.Usage = response.Usage
 			data.UsagePresence = response.UsagePresence
@@ -177,28 +289,38 @@ func (c *Coordinator) generateInjected(ctx context.Context, req domain.GenerateR
 		recorder.Attempt(data)
 	}
 	if err != nil {
-		return nil, err
+		return finish(nil, err)
 	}
 	if err := ctx.Err(); err != nil {
-		return nil, err
+		if captureEvidence {
+			return finish(response, err)
+		}
+		return finish(nil, err)
 	}
-	return response, nil
+	return finish(response, nil)
 }
 
-func (c *Coordinator) execute(ctx context.Context, backendID string, prepared *llm.PreparedGeneration) (outcome llm.AttemptOutcome, dispatched bool, capacityWait, generationDuration time.Duration) {
+func (c *Coordinator) execute(ctx context.Context, backendID string, prepared *llm.PreparedGeneration, captureEvidence bool) (outcome llm.AttemptOutcome, dispatched bool, capacityWait, generationDuration time.Duration, startedAt time.Time) {
 	start := c.now()
+	startedAt = start
 	release, err := c.manager.Acquire(ctx, backendID)
 	capacityWait = c.capacityWait(backendID, start)
 	if err != nil {
-		return llm.AttemptOutcome{Err: err}, false, capacityWait, 0
+		return llm.AttemptOutcome{Err: err}, false, capacityWait, 0, startedAt
 	}
 	defer release()
 	if err := ctx.Err(); err != nil {
-		return llm.AttemptOutcome{Err: err}, false, capacityWait, 0
+		return llm.AttemptOutcome{Err: err}, false, capacityWait, 0, startedAt
 	}
 	dispatchStart := c.now()
-	outcome = prepared.Execute(ctx)
-	return outcome, true, capacityWait, elapsed(dispatchStart, c.now())
+	if captureEvidence {
+		outcome = prepared.ExecuteWithEvidence(ctx)
+		dispatched = outcome.Evidence.DispatchInvoked
+	} else {
+		outcome = prepared.Execute(ctx)
+		dispatched = true
+	}
+	return outcome, dispatched, capacityWait, elapsed(dispatchStart, c.now()), startedAt
 }
 
 func (c *Coordinator) capacityWait(backendID string, start time.Time) time.Duration {
@@ -222,7 +344,8 @@ func attemptOutcome(err error) domain.ExecutionOutcome {
 	return domain.ExecutionOutcomeError
 }
 
-func attemptFailure(err error) domain.ExecutionFailureKind {
+// ClassifyFailure maps an execution error to the shared content-free category.
+func ClassifyFailure(err error) domain.ExecutionFailureKind {
 	if err == nil {
 		return domain.ExecutionFailureNone
 	}

internal/generation/evidence.go

@@ -0,0 +1,43 @@
+package generation
+
+import (
+	"time"
+
+	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
+	"gitea.maximumdirect.net/eric/promptkit/internal/llm"
+)
+
+// GenerationEvidence contains invocation-local request evidence without raw
+// provider bodies, headers, credentials, or generated content.
+type GenerationEvidence struct {
+	// InitialEndpoint is the frozen built-in request URL, if prepared.
+	// Injected generation leaves it unknown.
+	InitialEndpoint string
+	Attempts        []AttemptEvidence
+	RetryDelays     []time.Duration
+	Usage           domain.ObservedTokenUsage
+}
+
+// AttemptEvidence describes one capacity acquisition and any dispatch it
+// reached. Generated content remains on the separate response return value.
+type AttemptEvidence struct {
+	StartedAt                 time.Time
+	Dispatched                bool
+	ResponseReceived          bool
+	HTTP                      llm.HTTPExecutionEvidence
+	CapacityWait              time.Duration
+	RequestDuration           time.Duration
+	Failure                   domain.ExecutionFailureKind
+	Usage                     domain.ObservedTokenUsage
+	ResponseDecoded           bool
+	GenerationCompleted       bool
+	StructuredOutputRequested *bool
+}
+
+func cloneHTTPEvidence(evidence llm.HTTPExecutionEvidence) llm.HTTPExecutionEvidence {
+	if evidence.HTTPStatus != nil {
+		status := *evidence.HTTPStatus
+		evidence.HTTPStatus = &status
+	}
+	return evidence
+}

internal/generation/evidence_test.go

@@ -0,0 +1,321 @@
+package generation
+
+import (
+	"context"
+	"errors"
+	"net/http"
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"gitea.maximumdirect.net/eric/promptkit/internal/capacity"
+	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
+	"gitea.maximumdirect.net/eric/promptkit/internal/llm"
+)
+
+func TestGenerateWithEvidenceRetainsAttemptsAndUsage(t *testing.T) {
+	var now = time.Date(2026, 10, 13, 12, 0, 0, 0, time.UTC)
+	calls := 0
+	coordinator := testCoordinator(t, func(*http.Request) (*http.Response, error) {
+		calls++
+		if calls == 1 {
+			now = now.Add(4 * time.Millisecond)
+			return response(http.StatusServiceUnavailable, `{"error":{}}`), nil
+		}
+		now = now.Add(7 * time.Millisecond)
+		return response(http.StatusOK, `{"choices":[{"message":{"content":"ok"}}],"usage":{"prompt_tokens":3}}`), nil
+	})
+	coordinator.now = func() time.Time { return now }
+	coordinator.wait = func(context.Context, time.Duration) error {
+		now = now.Add(19 * time.Millisecond)
+		return nil
+	}
+
+	result, err, evidence := coordinator.GenerateWithEvidence(context.Background(), testRequest(1))
+	if err != nil || result == nil || result.Content != "ok" || calls != 2 {
+		t.Fatalf("result=%+v error=%v calls=%d", result, err, calls)
+	}
+	if len(evidence.Attempts) != 2 || len(evidence.RetryDelays) != 1 || evidence.RetryDelays[0] != 19*time.Millisecond {
+		t.Fatalf("attempts/delays = %#v / %#v", evidence.Attempts, evidence.RetryDelays)
+	}
+	first, second := evidence.Attempts[0], evidence.Attempts[1]
+	if !first.Dispatched || !first.HTTP.RequestObserved || !first.HTTP.ResponseReceived || first.HTTP.HTTPStatus == nil || *first.HTTP.HTTPStatus != http.StatusServiceUnavailable {
+		t.Fatalf("first attempt evidence = %+v", first)
+	}
+	if first.Failure != domain.ExecutionFailureProviderStatus || first.RequestDuration != 4*time.Millisecond {
+		t.Fatalf("first attempt failure/timing = %v / %v", first.Failure, first.RequestDuration)
+	}
+	if !second.Dispatched || !second.GenerationCompleted || !second.ResponseDecoded || second.HTTP.HTTPStatus == nil || *second.HTTP.HTTPStatus != http.StatusOK {
+		t.Fatalf("second attempt evidence = %+v", second)
+	}
+	if second.Failure != domain.ExecutionFailureNone || second.RequestDuration != 7*time.Millisecond {
+		t.Fatalf("second attempt failure/timing = %v / %v", second.Failure, second.RequestDuration)
+	}
+	if !second.Usage.PromptTokens.Known || !second.Usage.PromptTokens.Complete || second.Usage.PromptTokens.Value != 3 {
+		t.Fatalf("per-attempt usage = %+v", second.Usage.PromptTokens)
+	}
+	if !evidence.Usage.PromptTokens.Known || evidence.Usage.PromptTokens.Complete || evidence.Usage.PromptTokens.Value != 3 {
+		t.Fatalf("aggregate usage = %+v", evidence.Usage.PromptTokens)
+	}
+}
+
+func TestGenerateWithEvidenceRetainsExhaustedAttempts(t *testing.T) {
+	calls := 0
+	coordinator := testCoordinator(t, func(*http.Request) (*http.Response, error) {
+		calls++
+		return response(http.StatusServiceUnavailable, `{"error":{}}`), nil
+	})
+	coordinator.wait = func(context.Context, time.Duration) error { return nil }
+
+	result, err, evidence := coordinator.GenerateWithEvidence(context.Background(), testRequest(1))
+	var exhausted *ExhaustedError
+	if result != nil || !errors.As(err, &exhausted) || calls != 2 || exhausted.Attempts() != 2 {
+		t.Fatalf("result=%+v error=%v calls=%d", result, err, calls)
+	}
+	if len(evidence.Attempts) != 2 || len(evidence.RetryDelays) != 1 {
+		t.Fatalf("attempt/delay evidence = %#v / %#v", evidence.Attempts, evidence.RetryDelays)
+	}
+	for _, attempt := range evidence.Attempts {
+		if !attempt.Dispatched || attempt.Failure != domain.ExecutionFailureProviderStatus || attempt.HTTP.HTTPStatus == nil || *attempt.HTTP.HTTPStatus != http.StatusServiceUnavailable {
+			t.Fatalf("exhausted attempt evidence = %+v", attempt)
+		}
+	}
+	if evidence.Usage.PromptTokens.Known || evidence.Usage.PromptTokens.Complete {
+		t.Fatalf("missing provider usage was claimed: %+v", evidence.Usage.PromptTokens)
+	}
+}
+
+func TestGenerateWithEvidenceRetainsInterruptedBackoffWithoutAttempt(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	var now = time.Date(2026, 10, 13, 12, 0, 0, 0, time.UTC)
+	calls := 0
+	coordinator := testCoordinator(t, func(*http.Request) (*http.Response, error) {
+		calls++
+		now = now.Add(3 * time.Millisecond)
+		return response(http.StatusServiceUnavailable, `{"error":{}}`), nil
+	})
+	coordinator.now = func() time.Time { return now }
+	coordinator.wait = func(ctx context.Context, _ time.Duration) error {
+		now = now.Add(11 * time.Millisecond)
+		cancel()
+		return ctx.Err()
+	}
+
+	result, err, evidence := coordinator.GenerateWithEvidence(ctx, testRequest(2))
+	if result != nil || !errors.Is(err, context.Canceled) || calls != 1 {
+		t.Fatalf("result=%+v error=%v calls=%d", result, err, calls)
+	}
+	if len(evidence.Attempts) != 1 || !evidence.Attempts[0].Dispatched || len(evidence.RetryDelays) != 1 || evidence.RetryDelays[0] != 11*time.Millisecond {
+		t.Fatalf("interrupted evidence = %#v", evidence)
+	}
+	if evidence.Attempts[0].HTTP.HTTPStatus == nil || *evidence.Attempts[0].HTTP.HTTPStatus != http.StatusServiceUnavailable {
+		t.Fatalf("last dispatched response was lost: %+v", evidence.Attempts[0])
+	}
+}
+
+func TestGenerateWithEvidenceRecordsCanceledReacquisition(t *testing.T) {
+	var now = time.Date(2026, 10, 13, 12, 0, 0, 0, time.UTC)
+	calls := 0
+	coordinator := testCoordinator(t, func(*http.Request) (*http.Response, error) {
+		calls++
+		now = now.Add(2 * time.Millisecond)
+		return response(http.StatusServiceUnavailable, `{"error":{}}`), nil
+	})
+	coordinator.now = func() time.Time { return now }
+	baseContext, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	contextWithCancelOnWait := &cancelOnDoneContext{Context: baseContext, cancel: cancel}
+	var releaseHeld func()
+	coordinator.wait = func(context.Context, time.Duration) error {
+		release, err := coordinator.manager.Acquire(context.Background(), "limited")
+		if err != nil {
+			t.Fatalf("hold permit: %v", err)
+		}
+		releaseHeld = release
+		contextWithCancelOnWait.armed.Store(true)
+		return nil
+	}
+
+	// Signal cancellation only when the second acquisition has queued behind
+	// the held permit, avoiding scheduler- or sleep-based synchronization.
+	result, err, evidence := coordinator.GenerateWithEvidence(contextWithCancelOnWait, testRequest(2))
+	if releaseHeld != nil {
+		releaseHeld()
+	}
+	if result != nil || !errors.Is(err, context.Canceled) || calls != 1 {
+		t.Fatalf("result=%+v error=%v calls=%d", result, err, calls)
+	}
+	if len(evidence.Attempts) != 2 || !evidence.Attempts[0].Dispatched || evidence.Attempts[1].Dispatched {
+		t.Fatalf("acquisition evidence = %#v", evidence.Attempts)
+	}
+	if evidence.Attempts[1].Failure != domain.ExecutionFailureCanceled {
+		t.Fatalf("canceled acquisition failure = %v", evidence.Attempts[1].Failure)
+	}
+	if evidence.Attempts[0].HTTP.HTTPStatus == nil || *evidence.Attempts[0].HTTP.HTTPStatus != http.StatusServiceUnavailable {
+		t.Fatalf("last dispatched evidence was lost: %+v", evidence.Attempts)
+	}
+}
+
+func TestGenerateWithEvidenceNoDispatchHasCompleteZeroUsage(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+	coordinator := testCoordinator(t, func(*http.Request) (*http.Response, error) {
+		t.Fatal("canceled generation dispatched")
+		return nil, nil
+	})
+
+	result, err, evidence := coordinator.GenerateWithEvidence(ctx, testRequest(0))
+	if result != nil || !errors.Is(err, context.Canceled) || len(evidence.Attempts) != 0 {
+		t.Fatalf("result=%+v error=%v evidence=%+v", result, err, evidence)
+	}
+	if !evidence.Usage.PromptTokens.Known || !evidence.Usage.PromptTokens.Complete || evidence.Usage.PromptTokens.Value != 0 {
+		t.Fatalf("no-dispatch usage = %+v", evidence.Usage.PromptTokens)
+	}
+}
+
+func TestGenerateWithEvidenceForInjectedClient(t *testing.T) {
+	opaqueFailure := errors.New("injected client failed")
+	presence := &domain.TokenUsagePresence{PromptTokens: true}
+	for _, tc := range []struct {
+		name           string
+		response       *domain.GenerateResponse
+		err            error
+		wantResponse   bool
+		wantGeneration bool
+		wantFailure    domain.ExecutionFailureKind
+		wantUsage      bool
+		wantStructured bool
+	}{
+		{
+			name:           "success",
+			response:       &domain.GenerateResponse{Content: "private output", Usage: domain.TokenUsage{PromptTokens: 4}, UsagePresence: presence},
+			wantResponse:   true,
+			wantGeneration: true,
+			wantUsage:      true,
+			wantStructured: true,
+		},
+		{
+			name:        "nil response",
+			wantFailure: domain.ExecutionFailureMalformedResponse,
+		},
+		{
+			name:        "opaque failure",
+			err:         opaqueFailure,
+			wantFailure: domain.ExecutionFailureGeneration,
+		},
+		{
+			name:           "response with error",
+			response:       &domain.GenerateResponse{Content: "must not be evaluated", Usage: domain.TokenUsage{PromptTokens: 9}, UsagePresence: presence},
+			err:            opaqueFailure,
+			wantResponse:   true,
+			wantFailure:    domain.ExecutionFailureGeneration,
+			wantStructured: true,
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			client := &evidenceInjectedClient{response: tc.response, err: tc.err}
+			coordinator := newEvidenceInjectedCoordinator(t, client)
+			req := testRequest(7)
+			if tc.wantStructured {
+				req.StructuredOutput = &domain.StructuredOutputSpec{}
+			}
+
+			result, err, evidence := coordinator.GenerateWithEvidence(context.Background(), req)
+			if client.calls != 1 || len(evidence.Attempts) != 1 || len(evidence.RetryDelays) != 0 {
+				t.Fatalf("calls=%d attempts=%+v retry delays=%v", client.calls, evidence.Attempts, evidence.RetryDelays)
+			}
+			attempt := evidence.Attempts[0]
+			if !attempt.Dispatched || attempt.ResponseReceived != tc.wantResponse || attempt.GenerationCompleted != tc.wantGeneration || attempt.Failure != tc.wantFailure {
+				t.Fatalf("attempt evidence = %+v", attempt)
+			}
+			if attempt.HTTP != (llm.HTTPExecutionEvidence{}) {
+				t.Fatalf("injected call claimed HTTP evidence: %+v", attempt.HTTP)
+			}
+			if attempt.StructuredOutputRequested == nil || *attempt.StructuredOutputRequested != tc.wantStructured {
+				t.Fatalf("structured-output request fact = %v", attempt.StructuredOutputRequested)
+			}
+			if tc.wantFailure == domain.ExecutionFailureNone {
+				if err != nil || result == nil || result.Content != "private output" {
+					t.Fatalf("result=%+v error=%v", result, err)
+				}
+			} else if result != nil || err == nil {
+				t.Fatalf("result=%+v error=%v; expected failed call", result, err)
+			}
+			if attempt.Usage.PromptTokens.Known != tc.wantUsage || evidence.Usage.PromptTokens.Known != tc.wantUsage {
+				t.Fatalf("attempt/aggregate usage = %+v / %+v", attempt.Usage, evidence.Usage)
+			}
+			if tc.wantUsage && (attempt.Usage.PromptTokens.Value != 4 || evidence.Usage.PromptTokens.Value != 4) {
+				t.Fatalf("reported usage was not retained: %+v / %+v", attempt.Usage, evidence.Usage)
+			}
+		})
+	}
+}
+
+func TestGenerateWithEvidenceRetainsInjectedSuccessAfterCancellation(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	client := &evidenceInjectedClient{
+		response:      &domain.GenerateResponse{Content: "private output"},
+		afterGenerate: func() { cancel() },
+	}
+	coordinator := newEvidenceInjectedCoordinator(t, client)
+	req := testRequest(5)
+	req.StructuredOutput = &domain.StructuredOutputSpec{}
+
+	result, err, evidence := coordinator.GenerateWithEvidence(ctx, req)
+	if !errors.Is(err, context.Canceled) || result == nil || result.Content != "private output" {
+		t.Fatalf("result=%+v error=%v", result, err)
+	}
+	if client.calls != 1 || len(evidence.Attempts) != 1 {
+		t.Fatalf("calls=%d attempts=%+v", client.calls, evidence.Attempts)
+	}
+	attempt := evidence.Attempts[0]
+	if !attempt.ResponseReceived || !attempt.GenerationCompleted || attempt.Failure != domain.ExecutionFailureNone {
+		t.Fatalf("successful generation evidence was lost: %+v", attempt)
+	}
+	if attempt.HTTP != (llm.HTTPExecutionEvidence{}) {
+		t.Fatalf("injected call claimed HTTP evidence: %+v", attempt.HTTP)
+	}
+}
+
+type evidenceInjectedClient struct {
+	calls         int
+	response      *domain.GenerateResponse
+	err           error
+	afterGenerate func()
+}
+
+func (c *evidenceInjectedClient) Generate(context.Context, domain.GenerateRequest) (*domain.GenerateResponse, error) {
+	c.calls++
+	if c.afterGenerate != nil {
+		c.afterGenerate()
+	}
+	return c.response, c.err
+}
+
+func newEvidenceInjectedCoordinator(t *testing.T, client llm.Client) *Coordinator {
+	t.Helper()
+	manager, err := capacity.NewManager(map[string]domain.BackendCapacityPolicy{
+		"limited": {ConcurrencyLimit: 1},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	return NewInjected(manager, client)
+}
+
+type cancelOnDoneContext struct {
+	context.Context
+	cancel context.CancelFunc
+	once   sync.Once
+	armed  atomic.Bool
+}
+
+func (c *cancelOnDoneContext) Done() <-chan struct{} {
+	if c.armed.Load() {
+		c.once.Do(c.cancel)
+	}
+	return c.Context.Done()
+}

internal/llm/http_evidence.go

@@ -0,0 +1,191 @@
+package llm
+
+import (
+	"context"
+	"io"
+	"net/http"
+	"sync"
+	"time"
+
+	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
+)
+
+// HTTPExecutionEvidence contains only facts observable at the configured
+// RoundTripper boundary. It intentionally excludes request headers and bodies.
+type HTTPExecutionEvidence struct {
+	DispatchInvoked     bool
+	RequestObserved     bool
+	Endpoint            string
+	CredentialsSupplied bool
+	ResponseReceived    bool
+	HTTPStatus          *int
+}
+
+type httpEvidenceCollector struct {
+	mu       sync.Mutex
+	evidence HTTPExecutionEvidence
+}
+
+func (c *httpEvidenceCollector) observeRequest(request *http.Request) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	c.evidence.RequestObserved = true
+	c.evidence.Endpoint = endpointWithoutUserInfo(request)
+	c.evidence.CredentialsSupplied = requestHasCredentials(request)
+	c.evidence.ResponseReceived = false
+	c.evidence.HTTPStatus = nil
+}
+
+func (c *httpEvidenceCollector) observeResponse(response *http.Response) {
+	if response == nil {
+		return
+	}
+
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	status := response.StatusCode
+	c.evidence.ResponseReceived = true
+	c.evidence.HTTPStatus = &status
+}
+
+func (c *httpEvidenceCollector) snapshot() HTTPExecutionEvidence {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	evidence := c.evidence
+	if c.evidence.HTTPStatus != nil {
+		status := *c.evidence.HTTPStatus
+		evidence.HTTPStatus = &status
+	}
+	return evidence
+}
+
+type observingRoundTripper struct {
+	next     http.RoundTripper
+	evidence *httpEvidenceCollector
+}
+
+func (t observingRoundTripper) RoundTrip(request *http.Request) (*http.Response, error) {
+	t.evidence.observeRequest(request)
+	response, err := t.next.RoundTrip(request)
+	t.evidence.observeResponse(response)
+	return response, err
+}
+
+// doWithEvidence executes one request with a shallow copy of client. The copy
+// preserves timeout, redirect, and cookie-jar behavior without changing client.
+func doWithEvidence(client *http.Client, request *http.Request) (*http.Response, error, HTTPExecutionEvidence) {
+	if client == nil {
+		client = &http.Client{}
+	}
+
+	collector := &httpEvidenceCollector{}
+	clientCopy := *client
+	transport := clientCopy.Transport
+	if transport == nil {
+		transport = http.DefaultTransport
+	}
+	clientCopy.Transport = observingRoundTripper{next: transport, evidence: collector}
+
+	response, err := clientCopy.Do(request)
+	observed := collector.snapshot()
+	observed.DispatchInvoked = true
+	return response, err, observed
+}
+
+// GetWithEvidence performs a plain GET with the configured built-in HTTP
+// client. A positive timeoutSeconds applies to the request through response
+// body closure, matching the whole-request behavior of http.Client.Timeout.
+func (c *OpenAICompatibleClient) GetWithEvidence(
+	ctx context.Context,
+	endpoint string,
+	timeoutSeconds int,
+) (*http.Response, HTTPExecutionEvidence, error) {
+	return c.getWithEvidence(ctx, endpoint, timeoutSeconds, "")
+}
+
+// GetWithAuthenticationEvidence performs a plain GET with credentials resolved
+// from the selected target. Missing credentials are allowed for diagnostic
+// authentication probes even when generation requires a key.
+func (c *OpenAICompatibleClient) GetWithAuthenticationEvidence(
+	ctx context.Context,
+	endpoint string,
+	timeoutSeconds int,
+	target domain.ExecutionTarget,
+) (*http.Response, HTTPExecutionEvidence, error) {
+	return c.getWithEvidence(ctx, endpoint, timeoutSeconds, resolveAPIKey(target))
+}
+
+func (c *OpenAICompatibleClient) getWithEvidence(
+	ctx context.Context,
+	endpoint string,
+	timeoutSeconds int,
+	apiKey string,
+) (*http.Response, HTTPExecutionEvidence, error) {
+	requestContext := ctx
+	var cancel context.CancelFunc
+	if timeoutSeconds > 0 {
+		requestContext, cancel = context.WithTimeout(ctx, secondsDuration(timeoutSeconds))
+	}
+
+	request, err := http.NewRequestWithContext(requestContext, http.MethodGet, endpoint, nil)
+	if err != nil {
+		if cancel != nil {
+			cancel()
+		}
+		return nil, HTTPExecutionEvidence{}, err
+	}
+	if apiKey != "" {
+		request.Header.Set("Authorization", "Bearer "+apiKey)
+	}
+
+	response, err, evidence := doWithEvidence(c.httpClient, request)
+	if response == nil || response.Body == nil {
+		if cancel != nil {
+			cancel()
+		}
+		return response, evidence, err
+	}
+	if cancel != nil {
+		response.Body = &cancelOnCloseReadCloser{ReadCloser: response.Body, cancel: cancel}
+	}
+	return response, evidence, err
+}
+
+func secondsDuration(seconds int) time.Duration {
+	return time.Duration(seconds) * time.Second
+}
+
+type cancelOnCloseReadCloser struct {
+	io.ReadCloser
+	cancel context.CancelFunc
+	once   sync.Once
+}
+
+func (r *cancelOnCloseReadCloser) Close() error {
+	r.once.Do(r.cancel)
+	return r.ReadCloser.Close()
+}
+
+func endpointWithoutUserInfo(request *http.Request) string {
+	if request == nil || request.URL == nil {
+		return ""
+	}
+	endpoint := *request.URL
+	endpoint.User = nil
+	return endpoint.String()
+}
+
+func requestHasCredentials(request *http.Request) bool {
+	if request == nil {
+		return false
+	}
+	if request.Header.Get("Authorization") != "" {
+		return true
+	}
+	return request.URL != nil && request.URL.User != nil
+}
+
+var _ http.RoundTripper = observingRoundTripper{}
+var _ io.ReadCloser = (*cancelOnCloseReadCloser)(nil)

internal/llm/http_evidence_test.go

@@ -0,0 +1,340 @@
+package llm
+
+import (
+	"context"
+	"errors"
+	"io"
+	"net/http"
+	"net/http/cookiejar"
+	"net/http/httptest"
+	"strconv"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+
+	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
+)
+
+func TestGetWithEvidenceCapturesResponseAndOmitsURLUserInfo(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, request *http.Request) {
+		if request.Header.Get("Authorization") == "" {
+			t.Error("request did not carry URL user credentials")
+		}
+		w.WriteHeader(http.StatusNoContent)
+	}))
+	defer server.Close()
+
+	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{Timeout: time.Second})
+	if err != nil {
+		t.Fatalf("construct client: %v", err)
+	}
+	endpoint := strings.Replace(server.URL, "http://", "http://user:secret@", 1) + "/health"
+	response, evidence, err := client.GetWithEvidence(context.Background(), endpoint, 0)
+	if err != nil {
+		t.Fatalf("GET endpoint: %v", err)
+	}
+	if response == nil {
+		t.Fatal("GET returned no response")
+	}
+	response.Body.Close()
+
+	if !evidence.DispatchInvoked || !evidence.RequestObserved || !evidence.ResponseReceived {
+		t.Fatalf("incomplete response evidence: %+v", evidence)
+	}
+	if evidence.HTTPStatus == nil || *evidence.HTTPStatus != http.StatusNoContent {
+		t.Fatalf("status evidence = %v, want %d", evidence.HTTPStatus, http.StatusNoContent)
+	}
+	if !evidence.CredentialsSupplied {
+		t.Fatal("evidence did not record URL credentials")
+	}
+	if strings.Contains(evidence.Endpoint, "user") || strings.Contains(evidence.Endpoint, "secret") {
+		t.Fatalf("exposed endpoint contains URL user info: %q", evidence.Endpoint)
+	}
+	if want := server.URL + "/health"; evidence.Endpoint != want {
+		t.Fatalf("endpoint = %q, want %q", evidence.Endpoint, want)
+	}
+}
+
+func TestGetWithAuthenticationEvidenceResolvesOptionalCredentials(t *testing.T) {
+	tests := []struct {
+		name        string
+		target      domain.ExecutionTarget
+		environment string
+		wantAuth    string
+	}{
+		{
+			name: "direct key takes precedence",
+			target: domain.ExecutionTarget{
+				APIKey:    " direct-key ",
+				APIKeyEnv: "PROMPTKIT_DIAGNOSTIC_KEY",
+			},
+			environment: "environment-key",
+			wantAuth:    "Bearer direct-key",
+		},
+		{
+			name:        "environment key is used",
+			target:      domain.ExecutionTarget{APIKeyEnv: "PROMPTKIT_DIAGNOSTIC_KEY"},
+			environment: " environment-key ",
+			wantAuth:    "Bearer environment-key",
+		},
+		{
+			name:        "missing required key is optional here",
+			target:      domain.ExecutionTarget{APIKeyEnv: "PROMPTKIT_DIAGNOSTIC_KEY", APIKeyRequired: true},
+			environment: " ",
+		},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Setenv("PROMPTKIT_DIAGNOSTIC_KEY", tc.environment)
+			var authorization string
+			client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{
+				HTTPClient: &http.Client{Transport: roundTripFunc(func(request *http.Request) (*http.Response, error) {
+					authorization = request.Header.Get("Authorization")
+					return &http.Response{
+						StatusCode: http.StatusUnauthorized,
+						Header:     make(http.Header),
+						Body:       io.NopCloser(strings.NewReader("")),
+					}, nil
+				})},
+			})
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			response, evidence, err := client.GetWithAuthenticationEvidence(
+				context.Background(), "https://example.invalid/key", 0, tc.target,
+			)
+			if err != nil || response == nil {
+				t.Fatalf("response=%v error=%v", response, err)
+			}
+			response.Body.Close()
+			if authorization != tc.wantAuth || evidence.CredentialsSupplied != (tc.wantAuth != "") {
+				t.Fatalf("authorization=%q evidence=%+v", authorization, evidence)
+			}
+			if evidence.Endpoint != "https://example.invalid/key" || evidence.HTTPStatus == nil || *evidence.HTTPStatus != http.StatusUnauthorized {
+				t.Fatalf("HTTP evidence = %+v", evidence)
+			}
+		})
+	}
+}
+
+func TestDoWithEvidenceRecordsRequestWithoutResponse(t *testing.T) {
+	transportErr := errors.New("transport unavailable")
+	client := &http.Client{Transport: roundTripFunc(func(*http.Request) (*http.Response, error) {
+		return nil, transportErr
+	})}
+	request, err := http.NewRequest(http.MethodGet, "https://diagnostic.example/status", nil)
+	if err != nil {
+		t.Fatalf("create request: %v", err)
+	}
+
+	response, err, evidence := doWithEvidence(client, request)
+	if response != nil || !errors.Is(err, transportErr) {
+		t.Fatalf("response/error = %v/%v, want nil/transport error", response, err)
+	}
+	if !evidence.DispatchInvoked || !evidence.RequestObserved || evidence.ResponseReceived {
+		t.Fatalf("unexpected request evidence: %+v", evidence)
+	}
+	if evidence.HTTPStatus != nil || evidence.Endpoint != request.URL.String() || evidence.CredentialsSupplied {
+		t.Fatalf("unexpected evidence values: %+v", evidence)
+	}
+}
+
+func TestDoWithEvidenceRetainsResponseReturnedAlongsideError(t *testing.T) {
+	transportErr := errors.New("transport reported an error with a response")
+	client := &http.Client{Transport: roundTripFunc(func(request *http.Request) (*http.Response, error) {
+		return responseFor(request, http.StatusBadGateway, ""), transportErr
+	})}
+	request, err := http.NewRequest(http.MethodGet, "https://diagnostic.example/status", nil)
+	if err != nil {
+		t.Fatalf("create request: %v", err)
+	}
+
+	response, err, evidence := doWithEvidence(client, request)
+	if !errors.Is(err, transportErr) {
+		t.Fatalf("error = %v, want transport error", err)
+	}
+	if response != nil {
+		response.Body.Close()
+	}
+	if !evidence.RequestObserved || !evidence.ResponseReceived || evidence.HTTPStatus == nil || *evidence.HTTPStatus != http.StatusBadGateway {
+		t.Fatalf("observed response was lost alongside error: %+v", evidence)
+	}
+}
+
+func TestDoWithEvidenceUsesLastRedirectRequest(t *testing.T) {
+	var observedAuthorization []string
+	transport := roundTripFunc(func(request *http.Request) (*http.Response, error) {
+		observedAuthorization = append(observedAuthorization, request.Header.Get("Authorization"))
+		if request.URL.Host == "source.example" {
+			return responseFor(request, http.StatusFound, "https://other.example/final"), nil
+		}
+		return responseFor(request, http.StatusUnauthorized, ""), nil
+	})
+	client := &http.Client{Transport: transport}
+	request, err := http.NewRequest(http.MethodGet, "https://source.example/start", nil)
+	if err != nil {
+		t.Fatalf("create request: %v", err)
+	}
+	request.Header.Set("Authorization", "Bearer private-token")
+
+	response, err, evidence := doWithEvidence(client, request)
+	if err != nil {
+		t.Fatalf("follow redirect: %v", err)
+	}
+	if response == nil {
+		t.Fatal("redirect returned no response")
+	}
+	response.Body.Close()
+	if len(observedAuthorization) != 2 || observedAuthorization[0] == "" || observedAuthorization[1] != "" {
+		t.Fatalf("authorization across redirect = %#v", observedAuthorization)
+	}
+	if evidence.Endpoint != "https://other.example/final" || evidence.CredentialsSupplied {
+		t.Fatalf("evidence did not describe credential-stripped last hop: %+v", evidence)
+	}
+	if !evidence.ResponseReceived || evidence.HTTPStatus == nil || *evidence.HTTPStatus != http.StatusUnauthorized {
+		t.Fatalf("last-hop response evidence = %+v", evidence)
+	}
+}
+
+func TestDoWithEvidenceClearsPriorResponseOnFailedRedirect(t *testing.T) {
+	transportErr := errors.New("redirect target unavailable")
+	transport := roundTripFunc(func(request *http.Request) (*http.Response, error) {
+		if request.URL.Host == "source.example" {
+			return responseFor(request, http.StatusTemporaryRedirect, "https://target.example/unavailable"), nil
+		}
+		return nil, transportErr
+	})
+	client := &http.Client{Transport: transport}
+	request, err := http.NewRequest(http.MethodGet, "https://source.example/start", nil)
+	if err != nil {
+		t.Fatalf("create request: %v", err)
+	}
+
+	response, err, evidence := doWithEvidence(client, request)
+	if response != nil || !errors.Is(err, transportErr) {
+		t.Fatalf("response/error = %v/%v, want nil/transport error", response, err)
+	}
+	if !evidence.RequestObserved || evidence.Endpoint != "https://target.example/unavailable" {
+		t.Fatalf("evidence did not retain failed last request: %+v", evidence)
+	}
+	if evidence.ResponseReceived || evidence.HTTPStatus != nil {
+		t.Fatalf("prior redirect response was not cleared: %+v", evidence)
+	}
+}
+
+func TestDoWithEvidenceRetainsResponseWhenRedirectPolicyStops(t *testing.T) {
+	redirectErr := errors.New("redirect rejected")
+	transportCalls := 0
+	client := &http.Client{
+		Transport: roundTripFunc(func(request *http.Request) (*http.Response, error) {
+			transportCalls++
+			return responseFor(request, http.StatusFound, "https://other.example/never-requested"), nil
+		}),
+		CheckRedirect: func(*http.Request, []*http.Request) error { return redirectErr },
+	}
+	request, err := http.NewRequest(http.MethodGet, "https://source.example/start", nil)
+	if err != nil {
+		t.Fatalf("create request: %v", err)
+	}
+
+	response, err, evidence := doWithEvidence(client, request)
+	if !errors.Is(err, redirectErr) {
+		t.Fatalf("redirect error = %v, want policy error", err)
+	}
+	if response == nil || response.StatusCode != http.StatusFound {
+		t.Fatalf("redirect response = %v, want original response", response)
+	}
+	response.Body.Close()
+	if transportCalls != 1 || evidence.Endpoint != "https://source.example/start" {
+		t.Fatalf("redirect policy inferred or dispatched another request: calls=%d evidence=%+v", transportCalls, evidence)
+	}
+	if !evidence.ResponseReceived || evidence.HTTPStatus == nil || *evidence.HTTPStatus != http.StatusFound {
+		t.Fatalf("original response evidence was lost: %+v", evidence)
+	}
+}
+
+func TestGetWithEvidencePreservesClientAndIsolatesConcurrentCalls(t *testing.T) {
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, request *http.Request) {
+		w.WriteHeader(http.StatusNoContent)
+	}))
+	defer server.Close()
+
+	redirect := func(*http.Request, []*http.Request) error { return nil }
+	jar, err := cookiejar.New(nil)
+	if err != nil {
+		t.Fatalf("construct cookie jar: %v", err)
+	}
+
+	transport := http.DefaultTransport
+	supplied := &http.Client{Transport: transport, Timeout: 7 * time.Second, CheckRedirect: redirect, Jar: jar}
+	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{HTTPClient: supplied})
+	if err != nil {
+		t.Fatalf("construct client: %v", err)
+	}
+
+	const calls = 8
+	evidences := make([]HTTPExecutionEvidence, calls)
+	errs := make([]error, calls)
+	var wait sync.WaitGroup
+	for index := 0; index < calls; index++ {
+		wait.Add(1)
+		go func(index int) {
+			defer wait.Done()
+			endpoint := server.URL + "/call/" + strconv.Itoa(index)
+			response, evidence, getErr := client.GetWithEvidence(context.Background(), endpoint, 0)
+			if response != nil {
+				response.Body.Close()
+			}
+			evidences[index], errs[index] = evidence, getErr
+		}(index)
+	}
+	wait.Wait()
+
+	if supplied.Transport != transport || supplied.Timeout != 7*time.Second || supplied.CheckRedirect == nil || supplied.Jar != jar {
+		t.Fatal("diagnostic GET mutated the supplied HTTP client")
+	}
+	for index, evidence := range evidences {
+		if errs[index] != nil {
+			t.Fatalf("GET %d: %v", index, errs[index])
+		}
+		want := server.URL + "/call/" + strconv.Itoa(index)
+		if !evidence.RequestObserved || evidence.Endpoint != want {
+			t.Fatalf("GET %d evidence = %+v, want endpoint %q", index, evidence, want)
+		}
+	}
+}
+
+func TestGetWithEvidenceAppliesTargetTimeout(t *testing.T) {
+	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{Timeout: 5 * time.Second, HTTPClient: &http.Client{
+		Transport: roundTripFunc(func(request *http.Request) (*http.Response, error) {
+			<-request.Context().Done()
+			return nil, request.Context().Err()
+		}),
+	}})
+	if err != nil {
+		t.Fatalf("construct client: %v", err)
+	}
+
+	response, evidence, err := client.GetWithEvidence(context.Background(), "https://diagnostic.example/slow", 1)
+	if response != nil || !errors.Is(err, context.DeadlineExceeded) {
+		t.Fatalf("response/error = %v/%v, want nil/deadline exceeded", response, err)
+	}
+	if !evidence.DispatchInvoked || !evidence.RequestObserved || evidence.ResponseReceived {
+		t.Fatalf("timeout evidence = %+v", evidence)
+	}
+}
+
+func responseFor(request *http.Request, status int, location string) *http.Response {
+	header := make(http.Header)
+	if location != "" {
+		header.Set("Location", location)
+	}
+	return &http.Response{
+		StatusCode: status,
+		Header:     header,
+		Body:       io.NopCloser(strings.NewReader("")),
+		Request:    request,
+	}
+}

internal/llm/openai_compatible_client.go

@@ -101,24 +101,29 @@ func (c *OpenAICompatibleClient) Generate(ctx context.Context, req domain.Genera
 }
 
 // PreparedGeneration holds one encoded request and resolved authentication for
-// repeated attempts. Each Execute call creates a fresh HTTP request and context.
+// repeated attempts. Each execution creates a fresh HTTP request and context.
 type PreparedGeneration struct {
-	endpoint       string
-	payload        []byte
-	apiKey         string
-	timeoutSeconds int
-	httpClient     *http.Client
+	endpoint                  string
+	payload                   []byte
+	apiKey                    string
+	timeoutSeconds            int
+	httpClient                *http.Client
+	structuredOutputRequested bool
 }
 
 // AttemptOutcome describes one HTTP execution without exposing response bodies
 // or headers to the orchestration layer.
 type AttemptOutcome struct {
-	Response       *domain.GenerateResponse
-	Err            error
-	StatusCode     int
-	Usage          domain.TokenUsage
-	UsagePresence  *domain.TokenUsagePresence
-	RetryNotBefore time.Time
+	Response                  *domain.GenerateResponse
+	Err                       error
+	StatusCode                int
+	Usage                     domain.TokenUsage
+	UsagePresence             *domain.TokenUsagePresence
+	RetryNotBefore            time.Time
+	Evidence                  HTTPExecutionEvidence
+	StructuredOutputRequested *bool
+	ResponseDecoded           bool
+	GenerationCompleted       bool
 }
 
 // PrepareGeneration validates and freezes one built-in request before dispatch.
@@ -152,13 +157,15 @@ func (c *OpenAICompatibleClient) PrepareGeneration(req domain.GenerateRequest) (
 
 	payload, err := json.Marshal(wirePayload)
 	if err != nil {
+		for key, value := range req.Target.ExtraParams {
+			if _, extraErr := json.Marshal(value); extraErr != nil {
+				return nil, fmt.Errorf("%w: extra_params.%s must be JSON-serializable: %v", ErrInvalidRequest, key, extraErr)
+			}
+		}
 		return nil, fmt.Errorf("%w: failed to encode request: %v", ErrRequestFailed, err)
 	}
-	apiKey := strings.TrimSpace(req.Target.APIKey)
+	apiKey := resolveAPIKey(req.Target)
 	envName := strings.TrimSpace(req.Target.APIKeyEnv)
-	if apiKey == "" && envName != "" {
-		apiKey = strings.TrimSpace(os.Getenv(envName))
-	}
 	if apiKey == "" && req.Target.APIKeyRequired {
 		if envName != "" {
 			return nil, fmt.Errorf("%w: api key environment variable %q is not set", ErrInvalidRequest, envName)
@@ -172,12 +179,36 @@ func (c *OpenAICompatibleClient) PrepareGeneration(req domain.GenerateRequest) (
 	return &PreparedGeneration{
 		endpoint: endpoint, payload: payload, apiKey: apiKey,
 		timeoutSeconds: req.Target.TimeoutSeconds, httpClient: httpClient,
+		structuredOutputRequested: wireReq.ResponseFormat != nil,
 	}, nil
 }
 
+func resolveAPIKey(target domain.ExecutionTarget) string {
+	apiKey := strings.TrimSpace(target.APIKey)
+	if apiKey == "" {
+		if envName := strings.TrimSpace(target.APIKeyEnv); envName != "" {
+			apiKey = strings.TrimSpace(os.Getenv(envName))
+		}
+	}
+	return apiKey
+}
+
+// InitialEndpoint returns the frozen request URL before redirects.
+func (p *PreparedGeneration) InitialEndpoint() string { return p.endpoint }
+
 // Execute dispatches one attempt. The returned response is non-nil only when
 // the successful envelope contains a usable first choice.
 func (p *PreparedGeneration) Execute(ctx context.Context) AttemptOutcome {
+	return p.execute(ctx, false)
+}
+
+// ExecuteWithEvidence performs one prepared attempt and retains HTTP and
+// decoded-generation facts even when a later context check returns an error.
+func (p *PreparedGeneration) ExecuteWithEvidence(ctx context.Context) AttemptOutcome {
+	return p.execute(ctx, true)
+}
+
+func (p *PreparedGeneration) execute(ctx context.Context, captureEvidence bool) AttemptOutcome {
 	requestContext := ctx
 	if p.timeoutSeconds > 0 {
 		var cancel context.CancelFunc
@@ -193,13 +224,29 @@ func (p *PreparedGeneration) Execute(ctx context.Context) AttemptOutcome {
 		httpReq.Header.Set("Authorization", "Bearer "+p.apiKey)
 	}
 
-	httpResp, err := p.httpClient.Do(httpReq)
+	var (
+		httpResp *http.Response
+		outcome  AttemptOutcome
+	)
+	if captureEvidence {
+		httpResp, err, outcome.Evidence = doWithEvidence(p.httpClient, httpReq)
+		if outcome.Evidence.DispatchInvoked {
+			requested := p.structuredOutputRequested
+			outcome.StructuredOutputRequested = &requested
+		}
+	} else {
+		httpResp, err = p.httpClient.Do(httpReq)
+	}
+	if httpResp != nil && (captureEvidence || err == nil) {
+		outcome.StatusCode = httpResp.StatusCode
+	}
 	if err != nil {
-		return AttemptOutcome{Err: &requestFailedError{cause: err}}
+		outcome.Err = &requestFailedError{cause: err}
+		return outcome
 	}
 	receivedAt := time.Now()
 	defer httpResp.Body.Close()
-	outcome := AttemptOutcome{StatusCode: httpResp.StatusCode}
+	outcome.StatusCode = httpResp.StatusCode
 
 	if httpResp.StatusCode < 200 || httpResp.StatusCode >= 300 {
 		outcome.RetryNotBefore = retryNotBefore(httpResp.Header.Values("Retry-After"), receivedAt)
@@ -215,6 +262,11 @@ func (p *PreparedGeneration) Execute(ctx context.Context) AttemptOutcome {
 	}
 	if httpResp.ContentLength > maxOpenAIChatResponseBytes {
 		outcome.Err = openAIChatResponseTooLargeError()
+		if captureEvidence {
+			if contextErr := observedContextError(requestContext, ctx, outcome.Err); contextErr != nil {
+				outcome.Err = contextErr
+			}
+		}
 		return outcome
 	}
 
@@ -226,6 +278,7 @@ func (p *PreparedGeneration) Execute(ctx context.Context) AttemptOutcome {
 		}
 		return outcome
 	}
+	outcome.ResponseDecoded = true
 	outcome.Usage = domain.TokenUsage{
 		PromptTokens: tokenCount(wireResp.Usage.PromptTokens), CompletionTokens: tokenCount(wireResp.Usage.CompletionTokens),
 		TotalTokens: tokenCount(wireResp.Usage.TotalTokens), CachedTokens: tokenCount(wireResp.Usage.PromptTokensDetails.CachedTokens),
@@ -239,14 +292,30 @@ func (p *PreparedGeneration) Execute(ctx context.Context) AttemptOutcome {
 
 	if len(wireResp.Choices) == 0 {
 		outcome.Err = fmt.Errorf("%w: no choices returned", ErrMalformedResponse)
+		if captureEvidence {
+			if contextErr := observedContextError(requestContext, ctx, outcome.Err); contextErr != nil {
+				outcome.Err = contextErr
+			}
+		}
 		return outcome
 	}
 	content := wireResp.Choices[0].Message.Content
 	if content == nil {
 		outcome.Err = fmt.Errorf("%w: first choice has missing message content", ErrMalformedResponse)
+		if captureEvidence {
+			if contextErr := observedContextError(requestContext, ctx, outcome.Err); contextErr != nil {
+				outcome.Err = contextErr
+			}
+		}
 		return outcome
 	}
 	outcome.Response = &domain.GenerateResponse{Content: *content, Usage: outcome.Usage, UsagePresence: outcome.UsagePresence}
+	outcome.GenerationCompleted = true
+	if captureEvidence {
+		if contextErr := observedContextError(requestContext, ctx, nil); contextErr != nil {
+			outcome.Err = contextErr
+		}
+	}
 	return outcome
 }
 
@@ -446,9 +515,6 @@ func openAIChatRequestPayload(req openAIChatRequest) (map[string]any, error) {
 		if IsReservedOpenAIChatRequestField(key) {
 			return nil, fmt.Errorf("extra_params key %q collides with reserved request field", key)
 		}
-		if _, err := json.Marshal(value); err != nil {
-			return nil, fmt.Errorf("extra_params.%s must be JSON-serializable: %w", key, err)
-		}
 		out[key] = value
 	}
 

internal/llm/openai_compatible_client_test.go

@@ -1113,6 +1113,13 @@ func TestOpenAICompatibleClientRejectsInvalidExtraParamsBeforeProviderCall(t *te
 	}{
 		{name: "empty key", extraParams: map[string]any{"": "empty"}, want: "key must not be empty"},
 		{name: "unserializable value", extraParams: map[string]any{"bad": math.Inf(1)}, want: "JSON-serializable"},
+		{
+			name: "nested unserializable value",
+			extraParams: map[string]any{
+				"nested": map[string]any{"values": []any{"valid", math.NaN()}},
+			},
+			want: "extra_params.nested",
+		},
 	}
 	for _, key := range []string{
 		"model",
@@ -1161,6 +1168,56 @@ func TestOpenAICompatibleClientRejectsInvalidExtraParamsBeforeProviderCall(t *te
 	}
 }
 
+func TestOpenAICompatibleClientClassifiesSchemaEncodingFailures(t *testing.T) {
+	tests := []struct {
+		name        string
+		extraParams map[string]any
+		want        error
+		unwanted    error
+	}{
+		{
+			name:        "serializable extra keeps full-request failure",
+			extraParams: map[string]any{"client_option": "accepted"},
+			want:        ErrRequestFailed,
+			unwanted:    ErrInvalidRequest,
+		},
+		{
+			name:        "invalid extra keeps invalid-request failure",
+			extraParams: map[string]any{"nested": map[string]any{"bad": math.Inf(1)}},
+			want:        ErrInvalidRequest,
+			unwanted:    ErrRequestFailed,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			provider := newRecordingProvider(t)
+			client := newProviderClient(t, provider, OpenAICompatibleConfig{})
+			request := ordinaryGenerateRequest()
+			request.Target.ExtraParams = tc.extraParams
+			request.StructuredOutput = &domain.StructuredOutputSpec{
+				Type: domain.StructuredOutputJSONSchema,
+				JSONSchema: &domain.StructuredOutputJSONSpec{
+					Name:   "invalid-schema",
+					Strict: true,
+					Schema: json.RawMessage("{"),
+				},
+			}
+
+			_, err := client.Generate(context.Background(), request)
+			if err == nil || !errors.Is(err, tc.want) {
+				t.Fatalf("error = %v, want identity %v", err, tc.want)
+			}
+			if errors.Is(err, tc.unwanted) {
+				t.Fatalf("error = %v, unexpectedly has identity %v", err, tc.unwanted)
+			}
+			if calls := provider.requestCount(); calls != 0 {
+				t.Fatalf("provider calls = %d, want 0", calls)
+			}
+		})
+	}
+}
+
 func checkConfiguredModelFallback(t *testing.T) {
 	provider := newRecordingProvider(t)
 	client := newProviderClient(t, provider, OpenAICompatibleConfig{Model: "default-model"})

internal/llm/prepare_generation_benchmark_test.go

@@ -0,0 +1,119 @@
+package llm
+
+import (
+	"encoding/json"
+	"runtime"
+	"strings"
+	"testing"
+
+	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
+)
+
+var prepareGenerationBenchmarkSink *PreparedGeneration
+
+func BenchmarkPrepareGeneration(b *testing.B) {
+	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{
+		BaseURL: "https://api.example.test/v1",
+		Model:   "benchmark-model",
+	})
+	if err != nil {
+		b.Fatalf("construct benchmark client: %v", err)
+	}
+
+	prompt := domain.RenderedPrompt{
+		Messages: []domain.RenderedMessage{{Role: "user", Content: "Summarize this request."}},
+	}
+	tests := []struct {
+		name    string
+		request domain.GenerateRequest
+	}{
+		{
+			name: "no_extras",
+			request: domain.GenerateRequest{
+				Prompt: prompt,
+				Target: domain.ExecutionTarget{Model: "benchmark-model"},
+			},
+		},
+		{
+			name: "small_extras",
+			request: domain.GenerateRequest{
+				Prompt: prompt,
+				Target: domain.ExecutionTarget{Model: "benchmark-model", ExtraParams: map[string]any{
+					"priority": "low",
+					"attempt":  3,
+					"enabled":  true,
+				}},
+			},
+		},
+		{
+			name: "1MiB_string_extra",
+			request: domain.GenerateRequest{
+				Prompt: prompt,
+				Target: domain.ExecutionTarget{Model: "benchmark-model", ExtraParams: map[string]any{
+					"payload": strings.Repeat("x", 1<<20),
+				}},
+			},
+		},
+		{
+			name: "nested_json_extras",
+			request: domain.GenerateRequest{
+				Prompt: prompt,
+				Target: domain.ExecutionTarget{Model: "benchmark-model", ExtraParams: map[string]any{
+					"options": map[string]any{
+						"enabled": true,
+						"limits":  []any{2, 4, 8},
+						"tags":    []string{"summary", "offline"},
+					},
+				}},
+			},
+		},
+		{
+			name: "structured_output",
+			request: domain.GenerateRequest{
+				Prompt: prompt,
+				Target: domain.ExecutionTarget{Model: "benchmark-model"},
+				StructuredOutput: &domain.StructuredOutputSpec{
+					Type: domain.StructuredOutputJSONSchema,
+					JSONSchema: &domain.StructuredOutputJSONSpec{
+						Name:   "summary",
+						Strict: true,
+						Schema: map[string]any{
+							"type": "object",
+							"properties": map[string]any{
+								"summary": map[string]any{"type": "string"},
+								"count":   map[string]any{"type": "integer"},
+							},
+							"required":             []string{"summary", "count"},
+							"additionalProperties": false,
+						},
+					},
+				},
+			},
+		},
+	}
+
+	for _, tc := range tests {
+		b.Run(tc.name, func(b *testing.B) {
+			prepared, err := client.PrepareGeneration(tc.request)
+			if err != nil {
+				b.Fatalf("check prepared request: %v", err)
+			}
+			if !json.Valid(prepared.payload) {
+				b.Fatal("prepared request is not valid JSON")
+			}
+
+			b.ReportAllocs()
+			b.SetBytes(int64(len(prepared.payload)))
+			b.ResetTimer()
+			for range b.N {
+				prepared, err := client.PrepareGeneration(tc.request)
+				if err != nil {
+					b.Fatalf("prepare generation: %v", err)
+				}
+				prepareGenerationBenchmarkSink = prepared
+			}
+			b.StopTimer()
+			runtime.KeepAlive(prepareGenerationBenchmarkSink)
+		})
+	}
+}

internal/llm/prepared_generation_evidence_test.go

@@ -0,0 +1,222 @@
+package llm
+
+import (
+	"context"
+	"errors"
+	"io"
+	"net/http"
+	"strings"
+	"testing"
+
+	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
+)
+
+func TestPreparedGenerationEvidenceSeparatesResponseAndGenerationFacts(t *testing.T) {
+	tests := []struct {
+		name               string
+		status             int
+		body               string
+		structured         bool
+		wantDecoded        bool
+		wantGeneration     bool
+		wantResponse       bool
+		wantContent        string
+		wantFailure        error
+		wantUsagePresence  bool
+		wantStructuredFact bool
+	}{
+		{
+			name:               "valid content",
+			status:             http.StatusOK,
+			body:               `{"choices":[{"message":{"content":"ok"}}],"usage":{"prompt_tokens":0}}`,
+			structured:         true,
+			wantDecoded:        true,
+			wantGeneration:     true,
+			wantResponse:       true,
+			wantContent:        "ok",
+			wantUsagePresence:  true,
+			wantStructuredFact: true,
+		},
+		{
+			name:               "empty content",
+			status:             http.StatusOK,
+			body:               `{"choices":[{"message":{"content":""}}]}`,
+			wantDecoded:        true,
+			wantGeneration:     true,
+			wantResponse:       true,
+			wantStructuredFact: false,
+		},
+		{
+			name:               "decoded envelope without generated content",
+			status:             http.StatusOK,
+			body:               `{"choices":[],"usage":{"prompt_tokens":0}}`,
+			wantDecoded:        true,
+			wantUsagePresence:  true,
+			wantFailure:        ErrMalformedResponse,
+			wantStructuredFact: false,
+		},
+		{
+			name:               "malformed envelope",
+			status:             http.StatusOK,
+			body:               `not json`,
+			wantFailure:        ErrMalformedResponse,
+			wantStructuredFact: false,
+		},
+		{
+			name:               "provider status",
+			status:             http.StatusTooManyRequests,
+			body:               `{"error":{"message":"try again"}}`,
+			wantFailure:        ErrUnexpectedStatus,
+			wantStructuredFact: false,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{
+				BaseURL: "https://provider.example/v1",
+				Model:   "model",
+				HTTPClient: &http.Client{Transport: roundTripFunc(func(request *http.Request) (*http.Response, error) {
+					response := responseFor(request, test.status, "")
+					response.Body = io.NopCloser(strings.NewReader(test.body))
+					response.ContentLength = int64(len(test.body))
+					return response, nil
+				})},
+			})
+			if err != nil {
+				t.Fatal(err)
+			}
+			request := ordinaryGenerateRequest()
+			if test.structured {
+				request.StructuredOutput = &domain.StructuredOutputSpec{
+					Type: domain.StructuredOutputJSONSchema,
+					JSONSchema: &domain.StructuredOutputJSONSpec{
+						Name:   "smoke",
+						Schema: map[string]any{"type": "object"},
+					},
+				}
+			}
+			prepared, err := client.PrepareGeneration(request)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			outcome := prepared.ExecuteWithEvidence(context.Background())
+			if (outcome.Err != nil) != (test.wantFailure != nil) || (test.wantFailure != nil && !errors.Is(outcome.Err, test.wantFailure)) {
+				t.Fatalf("error = %v, want failure %v", outcome.Err, test.wantFailure)
+			}
+			if !outcome.Evidence.DispatchInvoked || !outcome.Evidence.RequestObserved || !outcome.Evidence.ResponseReceived {
+				t.Fatalf("response evidence = %+v", outcome.Evidence)
+			}
+			if outcome.Evidence.HTTPStatus == nil || *outcome.Evidence.HTTPStatus != test.status {
+				t.Fatalf("HTTP evidence status = %v, want %d", outcome.Evidence.HTTPStatus, test.status)
+			}
+			if outcome.GenerationCompleted != test.wantGeneration {
+				t.Fatalf("generation completed = %t, want %t", outcome.GenerationCompleted, test.wantGeneration)
+			}
+			if outcome.ResponseDecoded != test.wantDecoded {
+				t.Fatalf("response decoded = %t, want %t", outcome.ResponseDecoded, test.wantDecoded)
+			}
+			if (outcome.Response != nil) != test.wantResponse {
+				t.Fatalf("response presence = %t, want %t", outcome.Response != nil, test.wantResponse)
+			}
+			if test.wantResponse && outcome.Response.Content != test.wantContent {
+				t.Fatalf("generated content = %q, want %q", outcome.Response.Content, test.wantContent)
+			}
+			if (outcome.UsagePresence != nil && outcome.UsagePresence.PromptTokens) != test.wantUsagePresence {
+				t.Fatalf("usage presence = %+v, want prompt token presence %t", outcome.UsagePresence, test.wantUsagePresence)
+			}
+			if outcome.StructuredOutputRequested == nil || *outcome.StructuredOutputRequested != test.wantStructuredFact {
+				t.Fatalf("structured-output evidence = %v, want %t", outcome.StructuredOutputRequested, test.wantStructuredFact)
+			}
+		})
+	}
+}
+
+func TestPreparedGenerationEvidenceRetainsDecodedResponseOnCancellation(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	body := `{"choices":[{"message":{"content":"ok"}}],"usage":{"prompt_tokens":0}}`
+	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{
+		BaseURL: "https://provider.example/v1",
+		Model:   "model",
+		HTTPClient: &http.Client{Transport: roundTripFunc(func(request *http.Request) (*http.Response, error) {
+			return &http.Response{
+				StatusCode:    http.StatusOK,
+				Header:        make(http.Header),
+				Body:          &cancelAfterReadBody{Reader: strings.NewReader(body), cancel: cancel},
+				ContentLength: int64(len(body)),
+				Request:       request,
+			}, nil
+		})},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	prepared, err := client.PrepareGeneration(ordinaryGenerateRequest())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	outcome := prepared.ExecuteWithEvidence(ctx)
+	if !errors.Is(outcome.Err, context.Canceled) || !errors.Is(outcome.Err, ErrTransport) {
+		t.Fatalf("canceled outcome = %+v", outcome)
+	}
+	if !outcome.Evidence.ResponseReceived || outcome.Evidence.HTTPStatus == nil || *outcome.Evidence.HTTPStatus != http.StatusOK {
+		t.Fatalf("response evidence was lost after cancellation: %+v", outcome.Evidence)
+	}
+	if !outcome.ResponseDecoded || !outcome.GenerationCompleted || outcome.Response == nil || outcome.Response.Content != "ok" {
+		t.Fatalf("decoded generation was lost after cancellation: %+v", outcome)
+	}
+	if outcome.UsagePresence == nil || !outcome.UsagePresence.PromptTokens || outcome.Usage.PromptTokens != 0 {
+		t.Fatalf("decoded usage was lost after cancellation: %+v", outcome)
+	}
+}
+
+func TestPreparedGenerationEvidenceRecordsStructuredRequestAtDispatch(t *testing.T) {
+	transportErr := errors.New("provider unavailable")
+	client, err := NewOpenAICompatibleClient(OpenAICompatibleConfig{
+		BaseURL: "https://provider.example/v1",
+		Model:   "model",
+		HTTPClient: &http.Client{Transport: roundTripFunc(func(*http.Request) (*http.Response, error) {
+			return nil, transportErr
+		})},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	request := ordinaryGenerateRequest()
+	request.StructuredOutput = &domain.StructuredOutputSpec{
+		Type: domain.StructuredOutputJSONSchema,
+		JSONSchema: &domain.StructuredOutputJSONSpec{
+			Name:   "smoke",
+			Schema: map[string]any{"type": "object"},
+		},
+	}
+	prepared, err := client.PrepareGeneration(request)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	outcome := prepared.ExecuteWithEvidence(context.Background())
+	if !errors.Is(outcome.Err, transportErr) || !outcome.Evidence.DispatchInvoked || !outcome.Evidence.RequestObserved {
+		t.Fatalf("dispatch outcome = %+v", outcome)
+	}
+	if outcome.Evidence.ResponseReceived || outcome.StructuredOutputRequested == nil || !*outcome.StructuredOutputRequested {
+		t.Fatalf("structured request evidence = %+v, request=%v", outcome.Evidence, outcome.StructuredOutputRequested)
+	}
+}
+
+type cancelAfterReadBody struct {
+	io.Reader
+	cancel context.CancelFunc
+}
+
+func (b *cancelAfterReadBody) Read(buffer []byte) (int, error) {
+	n, err := b.Reader.Read(buffer)
+	if n > 0 {
+		b.cancel()
+	}
+	return n, err
+}
+
+func (b *cancelAfterReadBody) Close() error { return nil }

internal/observation/recorder.go

@@ -28,13 +28,13 @@ type Recorder struct {
 	capacityWait         time.Duration
 	generationDuration   time.Duration
 	retryDelay           time.Duration
-	usage                usageTotals
+	usage                UsageAccumulator
 }
 
 // Selection contains resolved identities only. Unresolved fields stay empty.
 type Selection struct {
 	PromptID      string
-	PromptVersion string
+	PromptVersion *string
 	ProfileID     string
 	BackendID     string
 	Model         string
@@ -79,8 +79,7 @@ func New(observer domain.ExecutionObserver) (*Recorder, error) {
 }
 
 func newRecorder(runID string, now func() time.Time, observer domain.ExecutionObserver) *Recorder {
-	return &Recorder{runID: runID, startedAt: now(), now: now, observer: observer,
-		usage: newUsageTotals()}
+	return &Recorder{runID: runID, startedAt: now(), now: now, observer: observer}
 }
 
 // NewRunID creates the identity shared by observations and successful results.
@@ -104,7 +103,10 @@ func (r *Recorder) Start() {
 }
 
 // UpdateSelection replaces the known resolved identities for later events.
-func (r *Recorder) UpdateSelection(selection Selection) { r.selection = selection }
+func (r *Recorder) UpdateSelection(selection Selection) {
+	selection.PromptVersion = copyStringPointer(selection.PromptVersion)
+	r.selection = selection
+}
 
 // Attempt records one completed acquisition and optional dispatch.
 func (r *Recorder) Attempt(data AttemptData) {
@@ -119,7 +121,7 @@ func (r *Recorder) Attempt(data AttemptData) {
 			r.lastRepairGeneration = data.Generation
 		}
 		r.generationDuration = addDuration(r.generationDuration, data.GenerationDuration)
-		r.usage.add(data.Usage, data.UsagePresence)
+		r.usage.Add(data.Usage, data.UsagePresence)
 	}
 	event := r.event(domain.ExecutionAttempt)
 	event.Generation = data.Generation
@@ -171,18 +173,26 @@ func (r *Recorder) Finish(data FinishData) {
 	if event.Duration < 0 {
 		event.Duration = 0
 	}
-	event.Usage = r.usage.snapshot(r.attempts)
+	event.Usage = r.usage.Observed()
 	r.deliver(event)
 }
 
 func (r *Recorder) event(kind domain.ExecutionEventKind) domain.ExecutionEvent {
 	return domain.ExecutionEvent{
 		Kind: kind, RunID: r.runID, Time: r.now(), PromptID: r.selection.PromptID,
-		PromptVersion: r.selection.PromptVersion, ProfileID: r.selection.ProfileID,
+		PromptVersion: copyStringPointer(r.selection.PromptVersion), ProfileID: r.selection.ProfileID,
 		BackendID: r.selection.BackendID, Model: r.selection.Model,
 	}
 }
 
+func copyStringPointer(value *string) *string {
+	if value == nil {
+		return nil
+	}
+	copy := *value
+	return &copy
+}
+
 func (r *Recorder) deliver(event domain.ExecutionEvent) {
 	if r.observer != nil {
 		r.observer(event)
@@ -243,7 +253,29 @@ type usageTotals struct {
 	prompt, completion, total, cached, cacheWrite usageField
 }
 
-func newUsageTotals() usageTotals {
+// UsageAccumulator combines presence-aware usage across dispatched attempts.
+// Its zero value represents no dispatched attempts.
+type UsageAccumulator struct {
+	totals   usageTotals
+	attempts uint64
+}
+
+// Add includes the usage reported by one dispatched attempt.
+func (u *UsageAccumulator) Add(usage domain.TokenUsage, presence *domain.TokenUsagePresence) {
+	if u.attempts == 0 {
+		u.totals = completeUsageTotals()
+	}
+	u.attempts++
+	u.totals.add(usage, presence)
+}
+
+// Observed returns aggregate counts, marking every field known and complete
+// when no attempt has been added.
+func (u UsageAccumulator) Observed() domain.ObservedTokenUsage {
+	return u.totals.snapshot(u.attempts)
+}
+
+func completeUsageTotals() usageTotals {
 	return usageTotals{prompt: usageField{complete: true}, completion: usageField{complete: true},
 		total: usageField{complete: true}, cached: usageField{complete: true}, cacheWrite: usageField{complete: true}}
 }

internal/observation/recorder_test.go

@@ -50,7 +50,8 @@ func TestRecorderAccountsDispatchedAttemptsAndReportedUsage(t *testing.T) {
 	var events []domain.ExecutionEvent
 	recorder := newRecorder("run-1", now, func(event domain.ExecutionEvent) { events = append(events, event) })
 	recorder.Start()
-	recorder.UpdateSelection(Selection{PromptID: "prompt", PromptVersion: "v1", ProfileID: "profile", BackendID: "backend", Model: "model"})
+	version := "v1"
+	recorder.UpdateSelection(Selection{PromptID: "prompt", PromptVersion: &version, ProfileID: "profile", BackendID: "backend", Model: "model"})
 	recorder.Attempt(AttemptData{
 		Generation: 1, Attempt: 1, Dispatched: true,
 		CapacityWait: 2 * time.Millisecond, GenerationDuration: 10 * time.Millisecond,

internal/observation/usage_accumulator_test.go

@@ -0,0 +1,27 @@
+package observation
+
+import (
+	"testing"
+
+	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
+)
+
+func TestUsageAccumulatorPreservesPresenceAndNoAttemptSemantics(t *testing.T) {
+	var empty UsageAccumulator
+	zero := empty.Observed()
+	if !zero.PromptTokens.Known || !zero.PromptTokens.Complete || zero.PromptTokens.Value != 0 ||
+		!zero.CacheWriteTokens.Known || !zero.CacheWriteTokens.Complete || zero.CacheWriteTokens.Value != 0 {
+		t.Fatalf("zero-attempt usage = %+v", zero)
+	}
+
+	var usage UsageAccumulator
+	usage.Add(domain.TokenUsage{PromptTokens: 0}, &domain.TokenUsagePresence{PromptTokens: true})
+	usage.Add(domain.TokenUsage{PromptTokens: 3}, &domain.TokenUsagePresence{PromptTokens: true})
+	observed := usage.Observed()
+	if observed.PromptTokens.Value != 3 || !observed.PromptTokens.Known || !observed.PromptTokens.Complete {
+		t.Fatalf("reported prompt usage = %+v", observed.PromptTokens)
+	}
+	if observed.CompletionTokens.Known || observed.CompletionTokens.Complete {
+		t.Fatalf("unreported completion usage = %+v", observed.CompletionTokens)
+	}
+}

internal/prompt/compiled_renderer_benchmark_test.go

@@ -0,0 +1,253 @@
+package prompt
+
+import (
+	"bytes"
+	"context"
+	"runtime"
+	"strconv"
+	"testing"
+	"text/template"
+
+	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
+)
+
+const rendererBenchmarkArtifactSize = 256 << 10
+
+var (
+	renderedPromptBenchmarkSink  *domain.RenderedPrompt
+	renderedPromptsBenchmarkSink []*domain.RenderedPrompt
+)
+
+type rendererBenchmarkIdentity struct {
+	id string
+}
+
+type rendererBenchmarkLookup struct {
+	identity  rendererBenchmarkIdentity
+	templates CompiledTemplates
+}
+
+func (lookup rendererBenchmarkLookup) GetCompiledTemplates(id string) (CompiledTemplates, bool) {
+	if id != lookup.identity.id {
+		return CompiledTemplates{}, false
+	}
+	return lookup.templates, true
+}
+
+type compiledRenderingBenchmarkCase struct {
+	name        string
+	renderer    Renderer
+	definition  *domain.PromptDefinition
+	inputs      map[string]*domain.Artifact
+	vars        map[string]string
+	ctx         context.Context
+	outputBytes int
+	check       func(*testing.B, *domain.RenderedPrompt)
+}
+
+func BenchmarkCompiledRendering(b *testing.B) {
+	body := bytes.Repeat([]byte("x"), rendererBenchmarkArtifactSize)
+	bodyText := string(body)
+
+	small := newCompiledRenderingBenchmarkCase(b,
+		"small_message", "", []string{"Summary for {{.audience}}."},
+		&domain.PromptDefinition{
+			ID: "compiled-render-benchmark", Version: stringPointerForTest("v1"),
+			Templates: []domain.PromptMessageTemplate{{Role: "user", Content: "Summary for {{.audience}}."}},
+		}, nil, map[string]string{"audience": "project leads"},
+		len("Summary for project leads."),
+		func(b *testing.B, rendered *domain.RenderedPrompt) {
+			if rendered.SessionID != "" || len(rendered.Messages) != 1 || rendered.Messages[0].Content != "Summary for project leads." {
+				b.Fatalf("unexpected small compiled render: %+v", rendered)
+			}
+		},
+	)
+
+	artifactInputs := map[string]*domain.Artifact{
+		"document": {Name: "document", Body: body},
+	}
+	largeContent := `{{input "document"}}`
+	largeDefinition := &domain.PromptDefinition{
+		ID: "compiled-render-benchmark", Version: stringPointerForTest("v1"),
+		Inputs:    []domain.PromptInput{{Name: "document"}},
+		Templates: []domain.PromptMessageTemplate{{Role: "user", Content: largeContent}},
+	}
+	large := newCompiledRenderingBenchmarkCase(b,
+		"artifact_backed_256KiB", "", []string{largeContent},
+		largeDefinition, artifactInputs, nil, len(bodyText),
+		func(b *testing.B, rendered *domain.RenderedPrompt) {
+			if len(rendered.Messages) != 1 {
+				b.Fatalf("artifact render message count=%d, want 1", len(rendered.Messages))
+			}
+			if rendered.Messages[0].Content != bodyText {
+				b.Fatalf("artifact render length=%d, want %d", len(rendered.Messages[0].Content), len(bodyText))
+			}
+		},
+	)
+
+	repeatedSession := `document-size={{len (input "document")}}`
+	repeatedMessages := []string{
+		`{{input "document"}}`,
+		`{{input "document"}}|{{input "document"}}`,
+	}
+	repeatedDefinition := &domain.PromptDefinition{
+		ID: "compiled-render-benchmark", Version: stringPointerForTest("v1"), SessionID: repeatedSession,
+		Inputs: []domain.PromptInput{{Name: "document"}},
+		Templates: []domain.PromptMessageTemplate{
+			{Role: "system", Content: repeatedMessages[0]},
+			{Role: "user", Content: repeatedMessages[1]},
+		},
+	}
+	repeatedOutputBytes := len(bodyText)*3 + 1
+	repeated := newCompiledRenderingBenchmarkCase(b,
+		"repeated_across_session_and_messages", repeatedSession, repeatedMessages,
+		repeatedDefinition, artifactInputs, nil, repeatedOutputBytes,
+		func(b *testing.B, rendered *domain.RenderedPrompt) {
+			if rendered.SessionID != "document-size="+strconv.Itoa(len(bodyText)) || len(rendered.Messages) != 2 ||
+				rendered.Messages[0].Content != bodyText || rendered.Messages[1].Content != bodyText+"|"+bodyText {
+				b.Fatalf("unexpected repeated compiled render: session=%q message lengths=%v", rendered.SessionID, renderedMessageLengths(rendered))
+			}
+		},
+	)
+
+	for _, benchmark := range []compiledRenderingBenchmarkCase{small, large, repeated} {
+		b.Run(benchmark.name, func(b *testing.B) {
+			rendered, err := benchmark.renderer.Render(benchmark.ctx, benchmark.definition, benchmark.inputs, benchmark.vars)
+			if err != nil {
+				b.Fatalf("check compiled renderer output: %v", err)
+			}
+			benchmark.check(b, rendered)
+
+			b.ReportAllocs()
+			b.SetBytes(int64(benchmark.outputBytes))
+			b.ResetTimer()
+			for range b.N {
+				rendered, err := benchmark.renderer.Render(benchmark.ctx, benchmark.definition, benchmark.inputs, benchmark.vars)
+				if err != nil {
+					b.Fatalf("render compiled template: %v", err)
+				}
+				renderedPromptBenchmarkSink = rendered
+			}
+			b.StopTimer()
+			runtime.KeepAlive(renderedPromptBenchmarkSink)
+		})
+	}
+}
+
+// BenchmarkRetainedRenderedOutput reports post-GC live heap for a fixed batch
+// of rendered outputs above the same fixture's setup-only baseline.
+func BenchmarkRetainedRenderedOutput(b *testing.B) {
+	body := bytes.Repeat([]byte("x"), rendererBenchmarkArtifactSize)
+	bodyText := string(body)
+	content := `{{input "document"}}`
+	definition := &domain.PromptDefinition{
+		ID: "retained-render-benchmark", Version: stringPointerForTest("v1"),
+		Inputs:    []domain.PromptInput{{Name: "document"}},
+		Templates: []domain.PromptMessageTemplate{{Role: "user", Content: content}},
+	}
+	compiled := CompiledTemplates{Messages: []*template.Template{mustCompileRendererBenchmarkTemplate(b, content)}}
+	renderer := NewCompiledRenderer(rendererBenchmarkLookup{
+		identity:  rendererBenchmarkIdentity{id: definition.ID},
+		templates: compiled,
+	})
+	inputs := map[string]*domain.Artifact{"document": {Name: "document", Body: body}}
+	ctx := context.Background()
+	const retainedBatchSize = 4
+	retained := make([]*domain.RenderedPrompt, retainedBatchSize)
+
+	check, err := renderer.Render(ctx, definition, inputs, nil)
+	if err != nil {
+		b.Fatalf("check retained-output fixture: %v", err)
+	}
+	if len(check.Messages) != 1 || check.Messages[0].Content != bodyText {
+		b.Fatalf("retained-output fixture returned unexpected content")
+	}
+	check = nil
+	// Repeated -count runs must start from the same setup-only heap baseline.
+	renderedPromptBenchmarkSink = nil
+	renderedPromptsBenchmarkSink = nil
+
+	runtime.GC()
+	var setupMemory runtime.MemStats
+	runtime.ReadMemStats(&setupMemory)
+	runtime.KeepAlive(renderer)
+	runtime.KeepAlive(definition)
+	runtime.KeepAlive(inputs)
+
+	b.ReportAllocs()
+	b.SetBytes(int64(len(bodyText)))
+	b.ResetTimer()
+	for iteration := 0; iteration < b.N; iteration++ {
+		rendered, err := renderer.Render(ctx, definition, inputs, nil)
+		if err != nil {
+			b.Fatalf("render retained-output fixture: %v", err)
+		}
+		retained[iteration%len(retained)] = rendered
+	}
+	b.StopTimer()
+	for i, rendered := range retained {
+		if rendered != nil {
+			continue
+		}
+		rendered, err := renderer.Render(ctx, definition, inputs, nil)
+		if err != nil {
+			b.Fatalf("fill retained-output fixture: %v", err)
+		}
+		retained[i] = rendered
+	}
+	renderedPromptsBenchmarkSink = retained
+	runtime.GC()
+	var retainedMemory runtime.MemStats
+	runtime.ReadMemStats(&retainedMemory)
+	b.ReportMetric(float64(int64(retainedMemory.HeapAlloc)-int64(setupMemory.HeapAlloc)), "retained-B")
+	runtime.KeepAlive(retained)
+	runtime.KeepAlive(renderer)
+	runtime.KeepAlive(definition)
+	runtime.KeepAlive(inputs)
+}
+
+func newCompiledRenderingBenchmarkCase(
+	b *testing.B,
+	name string,
+	session string,
+	messages []string,
+	definition *domain.PromptDefinition,
+	inputs map[string]*domain.Artifact,
+	vars map[string]string,
+	outputBytes int,
+	check func(*testing.B, *domain.RenderedPrompt),
+) compiledRenderingBenchmarkCase {
+	compiled := CompiledTemplates{}
+	if session != "" {
+		compiled.Session = mustCompileRendererBenchmarkTemplate(b, session)
+	}
+	for _, content := range messages {
+		compiled.Messages = append(compiled.Messages, mustCompileRendererBenchmarkTemplate(b, content))
+	}
+	return compiledRenderingBenchmarkCase{
+		name: name,
+		renderer: NewCompiledRenderer(rendererBenchmarkLookup{
+			identity:  rendererBenchmarkIdentity{id: definition.ID},
+			templates: compiled,
+		}),
+		definition: definition, inputs: inputs, vars: vars, ctx: context.Background(),
+		outputBytes: outputBytes, check: check,
+	}
+}
+
+func mustCompileRendererBenchmarkTemplate(b *testing.B, source string) *template.Template {
+	b.Helper()
+	compiled, err := CompileTemplate("benchmark", source)
+	if err != nil {
+		b.Fatalf("compile benchmark template: %v", err)
+	}
+	return compiled
+}
+
+func renderedMessageLengths(rendered *domain.RenderedPrompt) []int {
+	lengths := make([]int, len(rendered.Messages))
+	for i, message := range rendered.Messages {
+		lengths[i] = len(message.Content)
+	}
+	return lengths
+}

internal/prompt/go_renderer.go

@@ -1,7 +1,6 @@
 package prompt
 
 import (
-	"bytes"
 	"context"
 	"errors"
 	"fmt"
@@ -60,7 +59,7 @@ func (r *goRenderer) Render(ctx context.Context, definition *domain.PromptDefini
 	var compiled CompiledTemplates
 	if r.templates != nil {
 		var found bool
-		compiled, found = r.templates.GetCompiledTemplates(definition.ID, definition.Version)
+		compiled, found = r.templates.GetCompiledTemplates(definition.ID)
 		if !found || len(compiled.Messages) != len(definition.Templates) {
 			return nil, fmt.Errorf("%w: captured templates are unavailable", ErrRenderFailure)
 		}
@@ -126,7 +125,7 @@ func (r *goRenderer) Render(ctx context.Context, definition *domain.PromptDefini
 		if err := ctx.Err(); err != nil {
 			return nil, err
 		}
-		var buf bytes.Buffer
+		var buf strings.Builder
 		executeErr := tmpl.Execute(&buf, vars)
 		if err := ctx.Err(); err != nil {
 			return nil, err
@@ -235,7 +234,7 @@ func executeSessionTemplate(ctx context.Context, tmpl *template.Template, vars m
 	if err := ctx.Err(); err != nil {
 		return "", err
 	}
-	var buf bytes.Buffer
+	var buf strings.Builder
 	executeErr := tmpl.Execute(&buf, vars)
 	if err := ctx.Err(); err != nil {
 		return "", err

internal/prompt/renderer_test.go

@@ -4,8 +4,11 @@ import (
 	"bytes"
 	"context"
 	"errors"
+	"fmt"
 	"strings"
+	"sync"
 	"testing"
+	"text/template"
 
 	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
 )
@@ -501,6 +504,76 @@ func TestGoRendererArtifactTextLifecycle(t *testing.T) {
 	}
 }
 
+func TestCompiledRendererKeepsConcurrentRequestsIndependent(t *testing.T) {
+	const (
+		promptID = "concurrent-render"
+		version  = "v1"
+	)
+	sessionTemplate, err := CompileTemplate("session", "session-{{.request}}")
+	if err != nil {
+		t.Fatalf("compile session template: %v", err)
+	}
+	messageTemplate, err := CompileTemplate("message", `request={{.request}};document={{input "document"}}`)
+	if err != nil {
+		t.Fatalf("compile message template: %v", err)
+	}
+	renderer := NewCompiledRenderer(compiledRendererTestLookup{
+		id: promptID,
+		templates: CompiledTemplates{
+			Session:  sessionTemplate,
+			Messages: []*template.Template{messageTemplate},
+		},
+	})
+	definition := &domain.PromptDefinition{
+		ID: promptID, Version: stringPointerForTest(version), SessionID: "session-{{.request}}",
+		Inputs:    []domain.PromptInput{{Name: "document"}},
+		Templates: []domain.PromptMessageTemplate{{Role: "user", Content: `request={{.request}};document={{input "document"}}`}},
+	}
+
+	const requestCount = 24
+	errs := make(chan error, requestCount)
+	var wait sync.WaitGroup
+	wait.Add(requestCount)
+	for i := 0; i < requestCount; i++ {
+		go func(i int) {
+			defer wait.Done()
+			request := fmt.Sprintf("request-%d", i)
+			document := fmt.Sprintf("document-%d", i)
+			rendered, err := renderer.Render(context.Background(), definition,
+				map[string]*domain.Artifact{"document": {Body: []byte(document)}},
+				map[string]string{"request": request},
+			)
+			if err != nil {
+				errs <- fmt.Errorf("render %s: %w", request, err)
+				return
+			}
+			if rendered.SessionID != "session-"+request || len(rendered.Messages) != 1 ||
+				rendered.Messages[0].Content != "request="+request+";document="+document {
+				errs <- fmt.Errorf("render %s returned session %q and messages %#v", request, rendered.SessionID, rendered.Messages)
+			}
+		}(i)
+	}
+	wait.Wait()
+	close(errs)
+	for err := range errs {
+		t.Error(err)
+	}
+}
+
+type compiledRendererTestLookup struct {
+	id        string
+	templates CompiledTemplates
+}
+
+func (lookup compiledRendererTestLookup) GetCompiledTemplates(id string) (CompiledTemplates, bool) {
+	if id != lookup.id {
+		return CompiledTemplates{}, false
+	}
+	return lookup.templates, true
+}
+
+// BenchmarkGoRendererArtifactReferences measures NewGoRenderer's per-call
+// template-parsing fallback rather than the captured compiled path.
 func BenchmarkGoRendererArtifactReferences(b *testing.B) {
 	body := bytes.Repeat([]byte("document content "), (artifactTextChunkSize*4)/len("document content "))
 	inputs := map[string]*domain.Artifact{

internal/prompt/requirements.go

@@ -0,0 +1,978 @@
+package prompt
+
+import (
+	"context"
+	"sort"
+	"text/template"
+	"text/template/parse"
+
+	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
+)
+
+type requirementReachability uint8
+
+const (
+	requirementDefinite requirementReachability = iota
+	requirementPossible
+	requirementInactive
+)
+
+type dotIdentity uint8
+
+const (
+	dotRoot dotIdentity = iota
+	dotNonRoot
+	dotUnknown
+)
+
+type inputEvidence struct {
+	name        string
+	kind        domain.RequirementKind
+	declared    bool
+	applicable  bool
+	contentType *string
+	description *string
+	explanation string
+}
+
+type variableEvidence struct {
+	name        string
+	kind        domain.RequirementKind
+	applicable  bool
+	explanation string
+}
+
+type requirementIssueKey struct {
+	code         domain.RequirementIssueCode
+	inputName    string
+	variableName string
+}
+
+type conditionEvaluation struct {
+	value            any
+	known            bool
+	unsupported      bool
+	inputNameUnknown bool
+	missingVariables map[string]struct{}
+	contentInputs    map[string]struct{}
+}
+
+func (evaluation conditionEvaluation) truth() bool {
+	truth, ok := template.IsTrue(evaluation.value)
+	return evaluation.known && ok && truth
+}
+
+func (walker *requirementWalker) evaluateCondition(pipe *parse.PipeNode, reach requirementReachability, dot dotIdentity) conditionEvaluation {
+	if pipe == nil {
+		return conditionEvaluation{unsupported: true}
+	}
+	if len(pipe.Cmds) == 1 && len(pipe.Decl) == 0 && !pipe.IsAssign {
+		return walker.evaluateCommand(pipe.Cmds[0], reach, dot)
+	}
+	if name, ok := directInputPipeline(pipe); ok {
+		return walker.evaluateInputName(name, reach, dot)
+	}
+	before := walker.dependencies
+	visitReach := requirementPossible
+	if reach == requirementInactive {
+		visitReach = requirementInactive
+	}
+	if err := walker.visitPipe(pipe, visitReach, dot); err != nil {
+		return conditionEvaluation{unsupported: true}
+	}
+	return conditionEvaluation{unsupported: walker.dependencies != before}
+}
+
+func (walker *requirementWalker) evaluateCommand(command *parse.CommandNode, reach requirementReachability, dot dotIdentity) conditionEvaluation {
+	if command == nil || len(command.Args) == 0 {
+		return conditionEvaluation{unsupported: true}
+	}
+	identifier, isIdentifier := command.Args[0].(*parse.IdentifierNode)
+	if isIdentifier {
+		switch identifier.Ident {
+		case "input":
+			if reach == requirementInactive {
+				if len(command.Args) == 2 {
+					if name, ok := literalStringValue(command.Args[1]); ok {
+						walker.recordInput(name, requirementInactive)
+						return conditionEvaluation{}
+					}
+				}
+				for _, argument := range command.Args[1:] {
+					_ = walker.visit(argument, requirementInactive, dot)
+				}
+				return conditionEvaluation{}
+			}
+			if len(command.Args) == 2 {
+				if name, ok := command.Args[1].(*parse.StringNode); ok {
+					walker.recordInput(name.Text, reach)
+					return conditionEvaluation{contentInputs: map[string]struct{}{name.Text: {}}}
+				}
+				return walker.evaluateInputName(command.Args[1], reach, dot)
+			}
+			for _, argument := range command.Args[1:] {
+				_ = walker.visit(argument, requirementPossible, dot)
+			}
+			return walker.unresolvedInputName(conditionEvaluation{unsupported: true})
+		case "index":
+			if len(command.Args) == 3 {
+				if key, ok := command.Args[2].(*parse.StringNode); ok && isRootMap(command.Args[1], dot, walker.rootKnown) {
+					walker.recordOptionalVariable(key.Text, reach)
+					value, supplied := walker.vars[key.Text]
+					if !supplied {
+						value = ""
+					}
+					return conditionEvaluation{value: value, known: true}
+				}
+			}
+		case "not":
+			if len(command.Args) == 2 {
+				evaluation := walker.evaluateValue(command.Args[1], reach, dot)
+				if evaluation.known {
+					truth, ok := template.IsTrue(evaluation.value)
+					if ok {
+						evaluation.value = !truth
+					} else {
+						evaluation.known = false
+						evaluation.unsupported = true
+					}
+				}
+				return evaluation
+			}
+		case "eq", "ne":
+			if len(command.Args) == 3 {
+				left := walker.evaluateValue(command.Args[1], reach, dot)
+				right := walker.evaluateValue(command.Args[2], reach, dot)
+				result := mergeConditionEvaluations(left, right)
+				if left.known && right.known {
+					leftString, leftOK := left.value.(string)
+					rightString, rightOK := right.value.(string)
+					if leftOK && rightOK {
+						equal := leftString == rightString
+						if identifier.Ident == "ne" {
+							equal = !equal
+						}
+						result.value = equal
+						result.known = true
+						return result
+					}
+					result.unsupported = true
+				}
+				return result
+			}
+		}
+	}
+	if !isIdentifier && len(command.Args) == 1 {
+		return walker.evaluateValue(command.Args[0], reach, dot)
+	}
+	if reach == requirementInactive {
+		_ = walker.visitCommand(command, reach, dot)
+		return conditionEvaluation{}
+	}
+	before := walker.dependencies
+	_ = walker.visitCommand(command, requirementPossible, dot)
+	return conditionEvaluation{unsupported: walker.dependencies != before}
+}
+
+func (walker *requirementWalker) evaluateValue(node parse.Node, reach requirementReachability, dot dotIdentity) conditionEvaluation {
+	switch node := node.(type) {
+	case *parse.DotNode:
+		if dot == dotRoot {
+			return conditionEvaluation{value: walker.vars, known: true}
+		}
+		if dot == dotUnknown {
+			walker.unresolvedVariableScope(reach)
+		}
+		return conditionEvaluation{unsupported: true}
+	case *parse.StringNode:
+		return conditionEvaluation{value: node.Text, known: true}
+	case *parse.BoolNode:
+		return conditionEvaluation{value: node.True, known: true}
+	case *parse.NilNode:
+		return conditionEvaluation{value: nil, known: true}
+	case *parse.FieldNode:
+		if dot != dotRoot || len(node.Ident) == 0 {
+			if dot == dotUnknown {
+				walker.unresolvedVariableScope(reach)
+			}
+			return conditionEvaluation{unsupported: true}
+		}
+		name := node.Ident[0]
+		walker.recordVariable(name, reach)
+		if len(node.Ident) > 1 {
+			walker.addIssue("", name, "A chained field access is outside the direct-key scope.")
+			return conditionEvaluation{unsupported: true}
+		}
+		value, supplied := walker.vars[name]
+		if !supplied {
+			return conditionEvaluation{missingVariables: map[string]struct{}{name: {}}}
+		}
+		return conditionEvaluation{value: value, known: true}
+	case *parse.VariableNode:
+		if len(node.Ident) == 1 && node.Ident[0] == "$" && walker.rootKnown {
+			return conditionEvaluation{value: walker.vars, known: true}
+		}
+		if len(node.Ident) < 2 || node.Ident[0] != "$" || !walker.rootKnown {
+			walker.visitVariable(node, reach)
+			return conditionEvaluation{unsupported: true}
+		}
+		name := node.Ident[1]
+		walker.recordVariable(name, reach)
+		if len(node.Ident) > 2 {
+			walker.addIssue("", name, "A chained field access is outside the direct-key scope.")
+			return conditionEvaluation{unsupported: true}
+		}
+		value, supplied := walker.vars[name]
+		if !supplied {
+			return conditionEvaluation{missingVariables: map[string]struct{}{name: {}}}
+		}
+		return conditionEvaluation{value: value, known: true}
+	case *parse.CommandNode:
+		return walker.evaluateCommand(node, reach, dot)
+	case *parse.PipeNode:
+		return walker.evaluateCondition(node, reach, dot)
+	case *parse.ChainNode:
+		before := walker.dependencies
+		visitReach := requirementPossible
+		if reach == requirementInactive {
+			visitReach = requirementInactive
+		}
+		_ = walker.visit(node.Node, visitReach, dot)
+		return conditionEvaluation{unsupported: walker.dependencies != before}
+	default:
+		return conditionEvaluation{unsupported: true}
+	}
+}
+
+func (walker *requirementWalker) evaluateInputName(node parse.Node, reach requirementReachability, dot dotIdentity) conditionEvaluation {
+	evaluation := walker.evaluateValue(node, reach, dot)
+	if evaluation.known {
+		if name, ok := evaluation.value.(string); ok {
+			walker.recordInput(name, reach)
+			return conditionEvaluation{contentInputs: map[string]struct{}{name: {}}}
+		}
+		evaluation.unsupported = true
+	}
+	// Value analysis has already visited recognizable references, including
+	// the conservative fallback for unsupported expressions. Do not rescan
+	// the same subtree: nested computed names would multiply that work.
+	return walker.unresolvedInputName(evaluation)
+}
+
+func (walker *requirementWalker) unresolvedInputName(evaluation conditionEvaluation) conditionEvaluation {
+	for name := range evaluation.missingVariables {
+		walker.addIssueCode(domain.RequirementIssueMissingVariable, "", name, "A missing variable prevents resolving an input name.")
+	}
+	for name := range evaluation.contentInputs {
+		walker.addIssueCode(domain.RequirementIssueInputContent, name, "", "Captured input content affects an input name.")
+	}
+	walker.addIssueCode(domain.RequirementIssueDynamicInputName, "", "", "An input helper name is not statically available.")
+	walker.unknownInputEffect = true
+	evaluation.inputNameUnknown = true
+	return evaluation
+}
+
+func directInputPipeline(pipe *parse.PipeNode) (parse.Node, bool) {
+	if pipe == nil || len(pipe.Cmds) != 2 || len(pipe.Decl) != 0 || pipe.IsAssign {
+		return nil, false
+	}
+	input := pipe.Cmds[1]
+	if len(input.Args) != 1 {
+		return nil, false
+	}
+	identifier, ok := input.Args[0].(*parse.IdentifierNode)
+	if !ok || identifier.Ident != "input" {
+		return nil, false
+	}
+	value := pipe.Cmds[0]
+	if len(value.Args) > 0 {
+		valueIdentifier, isValueIdentifier := value.Args[0].(*parse.IdentifierNode)
+		if isValueIdentifier && valueIdentifier.Ident == "input" && len(value.Args) == 2 {
+			return value, true
+		}
+	}
+	if len(value.Args) == 1 {
+		return value.Args[0], true
+	}
+	if len(value.Args) == 3 {
+		function, ok := value.Args[0].(*parse.IdentifierNode)
+		if ok && function.Ident == "index" {
+			return value, true
+		}
+	}
+	return nil, false
+}
+
+func literalStringValue(node parse.Node) (string, bool) {
+	switch node := node.(type) {
+	case *parse.StringNode:
+		return node.Text, true
+	case *parse.PipeNode:
+		if len(node.Cmds) == 1 && len(node.Cmds[0].Args) == 1 && len(node.Decl) == 0 && !node.IsAssign {
+			return literalStringValue(node.Cmds[0].Args[0])
+		}
+	}
+	return "", false
+}
+
+func mergeConditionEvaluations(left, right conditionEvaluation) conditionEvaluation {
+	result := conditionEvaluation{
+		unsupported:      left.unsupported || right.unsupported,
+		inputNameUnknown: left.inputNameUnknown || right.inputNameUnknown,
+		missingVariables: make(map[string]struct{}, len(left.missingVariables)+len(right.missingVariables)),
+		contentInputs:    make(map[string]struct{}, len(left.contentInputs)+len(right.contentInputs)),
+	}
+	for name := range left.missingVariables {
+		result.missingVariables[name] = struct{}{}
+	}
+	for name := range right.missingVariables {
+		result.missingVariables[name] = struct{}{}
+	}
+	for name := range left.contentInputs {
+		result.contentInputs[name] = struct{}{}
+	}
+	for name := range right.contentInputs {
+		result.contentInputs[name] = struct{}{}
+	}
+	return result
+}
+
+func branchReach(parent requirementReachability, known, truth, selected bool) requirementReachability {
+	if parent == requirementInactive {
+		return requirementInactive
+	}
+	if !known {
+		return requirementPossible
+	}
+	if truth == selected {
+		if parent == requirementPossible {
+			return requirementPossible
+		}
+		return requirementDefinite
+	}
+	return requirementInactive
+}
+
+type requirementWalker struct {
+	ctx                   context.Context
+	vars                  map[string]string
+	inputs                map[string]*inputEvidence
+	variables             map[string]*variableEvidence
+	issues                map[requirementIssueKey]domain.RequirementIssue
+	complete              bool
+	rootKnown             bool
+	unknownInputEffect    bool
+	unknownVariableEffect bool
+	dependencies          int
+	templateSet           *template.Template
+	visitedTrees          map[*parse.Tree]bool
+}
+
+// AnalyzeRequirements collects the prompt dependencies recognizable from its
+// captured syntax. Branch bodies remain conditional until their conditions are
+// classified; unsupported dependency-bearing syntax makes the result partial.
+func AnalyzeRequirements(
+	ctx context.Context,
+	definition *domain.PromptDefinition,
+	snapshot RequirementSnapshot,
+	vars map[string]string,
+	sessionBypassed bool,
+) (domain.RequirementInspection, error) {
+	if err := ctx.Err(); err != nil {
+		return domain.RequirementInspection{}, err
+	}
+	result := domain.RequirementInspection{Complete: true}
+	if definition != nil {
+		result.PromptID = definition.ID
+		result.PromptVersion = copyString(definition.Version)
+	}
+	walker := &requirementWalker{
+		ctx:       ctx,
+		vars:      vars,
+		inputs:    make(map[string]*inputEvidence, len(snapshot.Inputs)),
+		variables: make(map[string]*variableEvidence),
+		issues:    make(map[requirementIssueKey]domain.RequirementIssue),
+		complete:  true,
+		rootKnown: true,
+	}
+	for _, input := range snapshot.Inputs {
+		if err := ctx.Err(); err != nil {
+			return domain.RequirementInspection{}, err
+		}
+		kind := domain.RequirementOptional
+		if input.Required {
+			kind = domain.RequirementRequired
+		}
+		walker.inputs[input.Name] = &inputEvidence{
+			name:        input.Name,
+			kind:        kind,
+			declared:    true,
+			contentType: copyString(input.ContentType),
+			description: copyString(input.Description),
+		}
+		if kind == domain.RequirementOptional {
+			walker.inputs[input.Name].explanation = "Declared as an optional input."
+		}
+	}
+	for _, message := range snapshot.Templates.Messages {
+		if err := walker.walkTemplate(message); err != nil {
+			return domain.RequirementInspection{}, err
+		}
+	}
+	if !sessionBypassed && snapshot.Templates.Session != nil {
+		if err := walker.walkTemplate(snapshot.Templates.Session); err != nil {
+			return domain.RequirementInspection{}, err
+		}
+	}
+	if err := ctx.Err(); err != nil {
+		return domain.RequirementInspection{}, err
+	}
+	return walker.result(result), nil
+}
+
+func (walker *requirementWalker) walkTemplate(compiled *template.Template) error {
+	if err := walker.ctx.Err(); err != nil {
+		return err
+	}
+	if compiled == nil || compiled.Tree == nil || compiled.Tree.Root == nil {
+		walker.addIssue("", "", "A captured template has no parsed root.")
+		return nil
+	}
+	previousSet := walker.templateSet
+	previousVisited := walker.visitedTrees
+	walker.templateSet = compiled
+	walker.visitedTrees = map[*parse.Tree]bool{compiled.Tree: true}
+	walker.rootKnown = true
+	err := walker.visit(compiled.Tree.Root, requirementDefinite, dotRoot)
+	walker.templateSet = previousSet
+	walker.visitedTrees = previousVisited
+	return err
+}
+
+func (walker *requirementWalker) visit(node parse.Node, reach requirementReachability, dot dotIdentity) error {
+	if err := walker.ctx.Err(); err != nil {
+		return err
+	}
+	if node == nil {
+		return nil
+	}
+	switch node := node.(type) {
+	case *parse.ListNode:
+		if node == nil {
+			return nil
+		}
+		for _, child := range node.Nodes {
+			if err := walker.visit(child, reach, dot); err != nil {
+				return err
+			}
+		}
+	case *parse.ActionNode:
+		return walker.visit(node.Pipe, reach, dot)
+	case *parse.IfNode:
+		if reach == requirementInactive {
+			if err := walker.visit(node.Pipe, requirementInactive, dot); err != nil {
+				return err
+			}
+			if err := walker.visit(node.List, requirementInactive, dot); err != nil {
+				return err
+			}
+			return walker.visit(node.ElseList, requirementInactive, dot)
+		}
+		condition := walker.evaluateCondition(node.Pipe, reach, dot)
+		before := walker.dependencies
+		thenReach := branchReach(reach, condition.known, condition.truth(), true)
+		elseReach := branchReach(reach, condition.known, condition.truth(), false)
+		if err := walker.visit(node.List, thenReach, dot); err != nil {
+			return err
+		}
+		if err := walker.visit(node.ElseList, elseReach, dot); err != nil {
+			return err
+		}
+		if !condition.known && walker.dependencies != before {
+			walker.recordConditionLimitation(condition)
+		}
+		return nil
+	case *parse.WithNode:
+		if reach == requirementInactive {
+			if err := walker.visit(node.Pipe, requirementInactive, dot); err != nil {
+				return err
+			}
+			bodyDot := walker.withDotIdentity(node.Pipe, dot, conditionEvaluation{})
+			if err := walker.visit(node.List, requirementInactive, bodyDot); err != nil {
+				return err
+			}
+			return walker.visit(node.ElseList, requirementInactive, dot)
+		}
+		condition := walker.evaluateCondition(node.Pipe, reach, dot)
+		before := walker.dependencies
+		thenReach := branchReach(reach, condition.known, condition.truth(), true)
+		elseReach := branchReach(reach, condition.known, condition.truth(), false)
+		bodyDot := walker.withDotIdentity(node.Pipe, dot, condition)
+		if err := walker.visit(node.List, thenReach, bodyDot); err != nil {
+			return err
+		}
+		if err := walker.visit(node.ElseList, elseReach, dot); err != nil {
+			return err
+		}
+		if !condition.known && walker.dependencies != before {
+			walker.recordConditionLimitation(condition)
+		}
+		return nil
+	case *parse.RangeNode:
+		if err := walker.visit(node.Pipe, reach, dot); err != nil {
+			return err
+		}
+		before := walker.dependencies
+		bodyReach := requirementPossible
+		if reach == requirementInactive {
+			bodyReach = requirementInactive
+		}
+		if err := walker.visit(node.List, bodyReach, dotNonRoot); err != nil {
+			return err
+		}
+		if err := walker.visit(node.ElseList, bodyReach, dot); err != nil {
+			return err
+		}
+		if reach != requirementInactive && walker.dependencies != before {
+			walker.addIssue("", "", "Dependencies inside a range are only conservatively enumerated.")
+		}
+	case *parse.TemplateNode:
+		pipeReach := requirementPossible
+		if reach == requirementInactive {
+			pipeReach = requirementInactive
+		}
+		if err := walker.visit(node.Pipe, pipeReach, dot); err != nil {
+			return err
+		}
+		if reach == requirementInactive {
+			return nil
+		}
+		called := walker.templateSet.Lookup(node.Name)
+		if called == nil || called.Tree == nil || called.Tree.Root == nil {
+			walker.addIssue("", "", "An invoked named template is unavailable for syntax inspection.")
+			return nil
+		}
+		if walker.visitedTrees[called.Tree] {
+			walker.addIssue("", "", "An invoked named template is scanned conservatively.")
+			return nil
+		}
+		walker.visitedTrees[called.Tree] = true
+		rootKnown := walker.rootKnown
+		walker.rootKnown = false
+		walker.unknownVariableEffect = true
+		err := walker.visit(called.Tree.Root, requirementPossible, dotNonRoot)
+		walker.rootKnown = rootKnown
+		if err != nil {
+			return err
+		}
+		walker.addIssue("", "", "An invoked named template is scanned conservatively.")
+	case *parse.PipeNode:
+		return walker.visitPipe(node, reach, dot)
+	case *parse.CommandNode:
+		return walker.visitCommand(node, reach, dot)
+	case *parse.FieldNode:
+		if dot == dotRoot && len(node.Ident) > 0 {
+			walker.recordVariable(node.Ident[0], reach)
+			if len(node.Ident) > 1 && reach != requirementInactive {
+				walker.addIssue("", node.Ident[0], "A chained field access is outside the direct-key scope.")
+			}
+		}
+		if dot == dotUnknown {
+			walker.unresolvedVariableScope(reach)
+		}
+	case *parse.DotNode:
+		if dot == dotUnknown {
+			walker.unresolvedVariableScope(reach)
+		}
+	case *parse.VariableNode:
+		walker.visitVariable(node, reach)
+	case *parse.ChainNode:
+		before := walker.dependencies
+		chainReach := requirementPossible
+		if reach == requirementInactive {
+			chainReach = requirementInactive
+		}
+		if err := walker.visit(node.Node, chainReach, dot); err != nil {
+			return err
+		}
+		if reach != requirementInactive && walker.dependencies != before {
+			walker.addIssue("", "", "A chained expression is not interpreted.")
+		}
+	case *parse.BreakNode, *parse.ContinueNode:
+		if reach != requirementInactive {
+			walker.addIssue("", "", "Loop control is outside the supported syntax scope.")
+		}
+	}
+	return nil
+}
+
+func (walker *requirementWalker) visitPipe(pipe *parse.PipeNode, reach requirementReachability, dot dotIdentity) error {
+	if pipe == nil {
+		return nil
+	}
+	if len(pipe.Cmds) == 1 && len(pipe.Decl) == 0 && !pipe.IsAssign {
+		return walker.visitCommand(pipe.Cmds[0], reach, dot)
+	}
+	if name, ok := directInputPipeline(pipe); ok {
+		if reach == requirementInactive {
+			if literal, known := literalStringValue(name); known {
+				walker.recordInput(literal, requirementInactive)
+				return nil
+			}
+			return walker.visit(name, requirementInactive, dot)
+		}
+		walker.evaluateInputName(name, reach, dot)
+		return nil
+	}
+	before := walker.dependencies
+	commandReach := requirementPossible
+	if reach == requirementInactive {
+		commandReach = requirementInactive
+	}
+	for _, command := range pipe.Cmds {
+		if err := walker.visitCommand(command, commandReach, dot); err != nil {
+			return err
+		}
+	}
+	if reach != requirementInactive && walker.dependencies != before {
+		walker.addIssue("", "", "A pipeline or variable assignment is not interpreted.")
+	}
+	if reach != requirementInactive {
+		for _, declaration := range pipe.Decl {
+			if len(declaration.Ident) > 0 && declaration.Ident[0] == "$" {
+				walker.rootKnown = false
+				walker.unknownVariableEffect = true
+				walker.addIssue("", "", "The root template binding is reassigned.")
+			}
+		}
+	}
+	return nil
+}
+
+func (walker *requirementWalker) visitCommand(command *parse.CommandNode, reach requirementReachability, dot dotIdentity) error {
+	if command == nil || len(command.Args) == 0 {
+		return nil
+	}
+	identifier, isIdentifier := command.Args[0].(*parse.IdentifierNode)
+	if isIdentifier && identifier.Ident == "input" {
+		if reach == requirementInactive {
+			if len(command.Args) == 2 {
+				if name, ok := literalStringValue(command.Args[1]); ok {
+					walker.recordInput(name, reach)
+					return nil
+				}
+			}
+			for _, argument := range command.Args[1:] {
+				if err := walker.visit(argument, requirementInactive, dot); err != nil {
+					return err
+				}
+			}
+			return nil
+		}
+		if len(command.Args) == 2 {
+			if name, ok := command.Args[1].(*parse.StringNode); ok {
+				walker.recordInput(name.Text, reach)
+				return nil
+			}
+			walker.evaluateInputName(command.Args[1], reach, dot)
+			return nil
+		}
+		for _, argument := range command.Args[1:] {
+			if err := walker.visit(argument, requirementPossible, dot); err != nil {
+				return err
+			}
+		}
+		walker.unresolvedInputName(conditionEvaluation{unsupported: true})
+		return nil
+	}
+	if isIdentifier && identifier.Ident == "index" && len(command.Args) == 3 {
+		if _, ok := command.Args[2].(*parse.StringNode); ok && isRootMap(command.Args[1], dot, walker.rootKnown) {
+			key := command.Args[2].(*parse.StringNode).Text
+			walker.recordOptionalVariable(key, reach)
+			return nil
+		}
+		// A local map may alias the caller root even though its value is not
+		// tracked. A lookup on it must not vanish from complete discovery.
+		if variable, ok := unwrapSingleValue(command.Args[1]).(*parse.VariableNode); ok && len(variable.Ident) == 1 {
+			walker.unresolvedVariableScope(reach)
+		}
+	}
+	if !isIdentifier && len(command.Args) == 1 {
+		return walker.visit(command.Args[0], reach, dot)
+	}
+	before := walker.dependencies
+	for index, argument := range command.Args {
+		if isIdentifier && index == 0 {
+			continue
+		}
+		argumentReach := requirementPossible
+		if reach == requirementInactive {
+			argumentReach = requirementInactive
+		}
+		if err := walker.visit(argument, argumentReach, dot); err != nil {
+			return err
+		}
+	}
+	if reach != requirementInactive && walker.dependencies != before {
+		walker.addIssue("", "", "A function call or computed expression is not interpreted.")
+	}
+	return nil
+}
+
+func (walker *requirementWalker) visitVariable(variable *parse.VariableNode, reach requirementReachability) {
+	if len(variable.Ident) < 2 {
+		return
+	}
+	if variable.Ident[0] != "$" {
+		walker.unresolvedVariableScope(reach)
+		return
+	}
+	if !walker.rootKnown {
+		if reach != requirementInactive {
+			walker.unknownVariableEffect = true
+			walker.addIssue("", "", "The root template binding is not known.")
+		}
+		return
+	}
+	walker.recordVariable(variable.Ident[1], reach)
+	if len(variable.Ident) > 2 && reach != requirementInactive {
+		walker.addIssue("", variable.Ident[1], "A chained field access is outside the direct-key scope.")
+	}
+}
+
+func (walker *requirementWalker) unresolvedVariableScope(reach requirementReachability) {
+	if reach != requirementInactive {
+		walker.unknownVariableEffect = true
+		walker.addIssue("", "", "A caller-variable scope is not statically known.")
+	}
+}
+
+func (walker *requirementWalker) withDotIdentity(pipe *parse.PipeNode, dot dotIdentity, condition conditionEvaluation) dotIdentity {
+	if pipe != nil && len(pipe.Cmds) == 1 && len(pipe.Decl) == 0 && !pipe.IsAssign && len(pipe.Cmds[0].Args) == 1 &&
+		isRootMap(pipe.Cmds[0].Args[0], dot, walker.rootKnown) {
+		return dotRoot
+	}
+	if condition.known {
+		if _, root := condition.value.(map[string]string); root {
+			return dotRoot
+		}
+		return dotNonRoot
+	}
+	if condition.inputNameUnknown ||
+		!condition.unsupported && (len(condition.missingVariables) > 0 || len(condition.contentInputs) > 0) {
+		// Supported caller values and input bodies are strings; supported
+		// comparisons and negation return booleans, never the root map.
+		return dotNonRoot
+	}
+	return dotUnknown
+}
+
+func isRootMap(node parse.Node, dot dotIdentity, rootKnown bool) bool {
+	switch node := unwrapSingleValue(node).(type) {
+	case *parse.DotNode:
+		return dot == dotRoot
+	case *parse.VariableNode:
+		return rootKnown && len(node.Ident) == 1 && node.Ident[0] == "$"
+	default:
+		return false
+	}
+}
+
+func unwrapSingleValue(node parse.Node) parse.Node {
+	for {
+		pipe, ok := node.(*parse.PipeNode)
+		if !ok || len(pipe.Cmds) != 1 || len(pipe.Decl) != 0 || pipe.IsAssign || len(pipe.Cmds[0].Args) != 1 {
+			return node
+		}
+		node = pipe.Cmds[0].Args[0]
+	}
+}
+
+func (walker *requirementWalker) recordInput(name string, reach requirementReachability) {
+	evidence := walker.inputs[name]
+	if evidence == nil {
+		evidence = &inputEvidence{
+			name: name, kind: domain.RequirementOptional,
+			explanation: "Declared as an optional input.",
+		}
+		walker.inputs[name] = evidence
+	}
+	if reach == requirementInactive {
+		if !evidence.applicable && evidence.kind != domain.RequirementRequired {
+			evidence.explanation = "This input is referenced only in a skipped template path."
+		}
+	} else {
+		evidence.applicable = true
+		walker.promoteInput(evidence, kindForReach(reach))
+		if evidence.kind == domain.RequirementRequired {
+			evidence.explanation = ""
+		} else if reach == requirementPossible {
+			evidence.explanation = "This reference is not known to be reached on every execution path."
+		}
+	}
+	if reach != requirementInactive {
+		walker.dependencies++
+	}
+}
+
+func (walker *requirementWalker) recordVariable(name string, reach requirementReachability) {
+	evidence := walker.variables[name]
+	if evidence == nil {
+		evidence = &variableEvidence{name: name, kind: domain.RequirementOptional}
+		walker.variables[name] = evidence
+	}
+	if reach == requirementInactive {
+		if !evidence.applicable {
+			evidence.explanation = "This variable is referenced only in a skipped template path."
+		}
+	} else {
+		evidence.applicable = true
+		walker.promoteVariable(evidence, kindForReach(reach))
+		if evidence.kind == domain.RequirementRequired {
+			evidence.explanation = ""
+		} else if reach == requirementPossible {
+			evidence.explanation = "This reference is not known to be reached on every execution path."
+		}
+	}
+	if reach != requirementInactive {
+		walker.dependencies++
+	}
+}
+
+func (walker *requirementWalker) recordOptionalVariable(name string, reach requirementReachability) {
+	evidence := walker.variables[name]
+	if evidence == nil {
+		evidence = &variableEvidence{name: name, kind: domain.RequirementOptional}
+		walker.variables[name] = evidence
+	}
+	if reach == requirementInactive {
+		if !evidence.applicable {
+			evidence.explanation = "This variable is referenced only in a skipped template path."
+		}
+	} else {
+		evidence.applicable = true
+	}
+	if evidence.kind == domain.RequirementOptional && reach != requirementInactive {
+		evidence.explanation = "This key is read through an optional map lookup."
+	}
+	if reach != requirementInactive {
+		walker.dependencies++
+	}
+}
+
+func (walker *requirementWalker) promoteInput(evidence *inputEvidence, kind domain.RequirementKind) {
+	if requirementRank(kind) > requirementRank(evidence.kind) {
+		evidence.kind = kind
+	}
+	if evidence.kind == domain.RequirementRequired {
+		evidence.explanation = ""
+	}
+}
+
+func (walker *requirementWalker) promoteVariable(evidence *variableEvidence, kind domain.RequirementKind) {
+	if requirementRank(kind) > requirementRank(evidence.kind) {
+		evidence.kind = kind
+	}
+	if evidence.kind == domain.RequirementRequired {
+		evidence.explanation = ""
+	}
+}
+
+func kindForReach(reach requirementReachability) domain.RequirementKind {
+	if reach == requirementPossible {
+		return domain.RequirementConditional
+	}
+	return domain.RequirementRequired
+}
+
+func requirementRank(kind domain.RequirementKind) int {
+	switch kind {
+	case domain.RequirementRequired:
+		return 3
+	case domain.RequirementConditional:
+		return 2
+	default:
+		return 1
+	}
+}
+
+func (walker *requirementWalker) addIssue(inputName, variableName, description string) {
+	walker.addIssueCode(domain.RequirementIssueUnsupportedConstruct, inputName, variableName, description)
+}
+
+func (walker *requirementWalker) addIssueCode(code domain.RequirementIssueCode, inputName, variableName, description string) {
+	walker.complete = false
+	issue := domain.RequirementIssue{
+		Code:         code,
+		InputName:    inputName,
+		VariableName: variableName,
+		Description:  description,
+	}
+	key := requirementIssueKey{code: issue.Code, inputName: inputName, variableName: variableName}
+	walker.issues[key] = issue
+}
+
+func (walker *requirementWalker) recordConditionLimitation(condition conditionEvaluation) {
+	for name := range condition.missingVariables {
+		walker.addIssueCode(domain.RequirementIssueMissingVariable, "", name, "A missing variable prevents selecting a dependency-bearing branch.")
+	}
+	for name := range condition.contentInputs {
+		walker.addIssueCode(domain.RequirementIssueInputContent, name, "", "Captured input content affects branch selection.")
+	}
+	if condition.unsupported && !condition.inputNameUnknown ||
+		(len(condition.missingVariables) == 0 && len(condition.contentInputs) == 0 && !condition.inputNameUnknown) {
+		walker.addIssue("", "", "A dependency-bearing branch condition is not resolved by the supported syntax analysis.")
+	}
+}
+
+func (walker *requirementWalker) result(result domain.RequirementInspection) domain.RequirementInspection {
+	result.Complete = walker.complete
+	result.Inputs = make([]domain.InputRequirement, 0, len(walker.inputs))
+	for _, evidence := range walker.inputs {
+		if walker.unknownInputEffect && evidence.kind != domain.RequirementRequired {
+			evidence.kind = domain.RequirementConditional
+			evidence.explanation = "An unresolved input name could refer to this input."
+		}
+		result.Inputs = append(result.Inputs, domain.InputRequirement{
+			Name: evidence.name, Kind: evidence.kind, Declared: evidence.declared,
+			ContentType: copyString(evidence.contentType), Description: copyString(evidence.description),
+			Explanation: evidence.explanation,
+		})
+	}
+	sort.Slice(result.Inputs, func(i, j int) bool { return result.Inputs[i].Name < result.Inputs[j].Name })
+	result.Variables = make([]domain.VariableRequirement, 0, len(walker.variables))
+	for _, evidence := range walker.variables {
+		if walker.unknownVariableEffect && evidence.kind != domain.RequirementRequired {
+			evidence.kind = domain.RequirementConditional
+			evidence.explanation = "An unresolved caller-variable scope could refer to this variable."
+		}
+		_, supplied := walker.vars[evidence.name]
+		result.Variables = append(result.Variables, domain.VariableRequirement{
+			Name: evidence.name, Kind: evidence.kind, Supplied: supplied, Explanation: evidence.explanation,
+		})
+	}
+	sort.Slice(result.Variables, func(i, j int) bool { return result.Variables[i].Name < result.Variables[j].Name })
+	result.Issues = make([]domain.RequirementIssue, 0, len(walker.issues))
+	for _, issue := range walker.issues {
+		result.Issues = append(result.Issues, issue)
+	}
+	sort.Slice(result.Issues, func(i, j int) bool {
+		left, right := result.Issues[i], result.Issues[j]
+		if left.Code != right.Code {
+			return left.Code < right.Code
+		}
+		if left.InputName != right.InputName {
+			return left.InputName < right.InputName
+		}
+		return left.VariableName < right.VariableName
+	})
+	return result
+}
+
+func copyString(value *string) *string {
+	if value == nil {
+		return nil
+	}
+	copy := *value
+	return &copy
+}