Add artifact reading and output validation

docs/internal/overview.md

@@ -19,10 +19,12 @@ contributor workflow and validation.
 | `internal/profile` | Loads strictly decoded, validated execution profiles from filesystem and `fs.FS` sources and composes repositories with error-preserving fallback. | [Profile repositories](../../internal/profile/filesystem_repository.go) |
 | `internal/profile/builtin` | Embeds the built-in execution profile catalog and combines it with an optional primary repository. | [Built-in profile repository](../../internal/profile/builtin/repository.go) |
 | `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/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. | [Internal sources and validation](sources.md) |
 
 These packages provide the internal model, source, and rendering foundation.
-Artifact reading, output validation, model clients, orchestration, and a usable
+Model clients, orchestration, and a usable public engine are not implemented in
-public engine are not implemented in Promptkit yet.
+Promptkit yet.
 
 ## Maintenance
 

docs/internal/sources.md

@@ -0,0 +1,67 @@
+# Internal Sources And Validation
+
+## Purpose
+
+This document describes Promptkit's implemented internal source, artifact,
+rendering, and output-validation behavior. The
+[architecture policy](../policy/architecture.md) owns the library boundary and
+dependency rules. None of these internal packages is a supported consumer API,
+and the root package does not yet assemble them into a usable engine.
+
+## Prompt Definitions
+
+`internal/promptdef` loads prompt definitions from an operating-system
+filesystem or an `fs.FS`. It discovers YAML deterministically, decodes fields
+strictly, validates definitions, selects an ID and optional version, and
+resolves file-backed message content within the selected source.
+
+Its package tests own prompt selection, strict decoding, definition validation,
+duplicate detection, and source containment:
+[prompt-definition repository tests](../../internal/promptdef/repository_test.go).
+
+## Profiles And Built-Ins
+
+`internal/profile` loads strictly decoded execution profiles from an
+operating-system filesystem or an `fs.FS`. It validates required profile data,
+rejects raw API keys, and supports a primary repository with fallback only
+when the primary reports that a profile is absent.
+
+`internal/profile/builtin` embeds the maintained built-in profile catalog and
+can place a caller-selected repository ahead of that catalog. Profile behavior
+is owned by the
+[profile repository tests](../../internal/profile/repository_test.go), while
+catalog completeness, duplicate IDs, and overlay behavior are owned by the
+[built-in repository tests](../../internal/profile/builtin/repository_test.go).
+
+## Ordinary Artifacts
+
+`internal/artifact` resolves inline references and unrestricted,
+caller-selected file paths. It copies content into an artifact, records
+metadata and a content hash, applies a content-type fallback, and honors
+context cancellation.
+
+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
+HTTP request-size policy. Scriptorium's restricted HTTP reader remains an
+application concern outside Promptkit. The
+[artifact reader tests](../../internal/artifact/reader_test.go) own the
+implemented reader behavior and failures.
+
+## Rendering
+
+`internal/prompt` renders definition messages as Go templates using named
+artifacts and variables. It carries message roles, session IDs, and cache
+control into the rendered prompt. The
+[renderer tests](../../internal/prompt/renderer_test.go) own rendering behavior.
+
+## Schemas And Output Validation
+
+`internal/validate` provides validators backed by an operating-system
+filesystem or an `fs.FS`. Validation can be skipped, require non-empty output,
+require JSON, or apply a JSON Schema loaded with the source's path semantics.
+Invalid generated content is returned as a validation result; inability to
+load, register, or compile a schema is an operational error.
+
+The [validator tests](../../internal/validate/standard_validator_test.go) own
+basic, JSON, JSON Schema, source resolution, schema loading, compilation, and
+content-failure behavior.

docs/policy/architecture.md

@@ -29,14 +29,20 @@ The implemented internal components consist of:
 - `internal/profile`, which loads, validates, and overlays execution profiles
   from filesystem and `fs.FS` sources;
 - `internal/profile/builtin`, which embeds the built-in execution profile
-  catalog; and
+  catalog;
-- `internal/prompt`, which renders prompt messages from Go templates.
+- `internal/prompt`, which renders prompt messages from Go templates;
+- `internal/artifact`, which resolves ordinary inline and unrestricted
+  caller-selected file references; and
+- `internal/validate`, which validates basic, JSON, and JSON Schema output
+  using filesystem and `fs.FS` schema sources.
 
 The defaults and renderer depend on the domain model. Prompt-definition and
 profile repositories use the domain model, file catalog, and YAML decoder. The
 built-in profile repository supplies an embedded `fs.FS` to the profile
-package. Artifact reading, output validation, model clients, orchestration, and
+package. Artifact reading uses the domain model and application-neutral
-the public engine have not yet been extracted.
+defaults. Validation uses the domain model, file catalog, and JSON Schema
+implementation. Model clients, orchestration, and the public engine have not
+yet been extracted.
 
 Future framework extraction must follow this dependency direction:
 

go.mod

@@ -2,4 +2,9 @@ module gitea.maximumdirect.net/eric/promptkit
 
 go 1.25.5
 
-require gopkg.in/yaml.v3 v3.0.1
+require (
+	github.com/santhosh-tekuri/jsonschema/v6 v6.0.2
+	gopkg.in/yaml.v3 v3.0.1
+)
+
+require golang.org/x/text v0.14.0 // indirect

go.sum

@@ -1,3 +1,9 @@
+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=
+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/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=

internal/artifact/reader.go

@@ -0,0 +1,122 @@
+package artifact
+
+import (
+	"context"
+	"crypto/sha256"
+	"errors"
+	"fmt"
+	"io"
+	"mime"
+	"os"
+	"path/filepath"
+
+	"gitea.maximumdirect.net/eric/promptkit/internal/defaults"
+	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
+)
+
+var (
+	ErrUnsupportedRefType = errors.New("unsupported artifact reference type")
+	ErrMissingInlineBody  = errors.New("missing body for inline artifact")
+	ErrMissingFilePath    = errors.New("missing file path for file artifact")
+)
+
+// Reader resolves artifact references into actual artifacts.
+type Reader interface {
+	Read(ctx context.Context, ref domain.ArtifactRef) (*domain.Artifact, error)
+}
+
+// CompositeReader routes artifact resolution based on the reference type.
+type CompositeReader struct {
+	inlineReader *inlineReader
+	fileReader   Reader
+}
+
+func NewCompositeReader() Reader {
+	return &CompositeReader{
+		inlineReader: &inlineReader{},
+		fileReader:   &fileReader{},
+	}
+}
+
+func (c *CompositeReader) Read(ctx context.Context, ref domain.ArtifactRef) (*domain.Artifact, error) {
+	select {
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	default:
+	}
+
+	switch ref.Type {
+	case domain.ArtifactRefInline:
+		return c.inlineReader.Read(ctx, ref)
+	case domain.ArtifactRefFile:
+		return c.fileReader.Read(ctx, ref)
+	default:
+		return nil, fmt.Errorf("%w: %s", ErrUnsupportedRefType, ref.Type)
+	}
+}
+
+type inlineReader struct{}
+
+func (r *inlineReader) Read(ctx context.Context, ref domain.ArtifactRef) (*domain.Artifact, error) {
+	select {
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	default:
+	}
+
+	if ref.Body == "" {
+		return nil, ErrMissingInlineBody
+	}
+
+	body := []byte(ref.Body)
+	return &domain.Artifact{
+		ContentType: defaults.ContentTypeTextPlain,
+		Body:        body,
+		Size:        int64(len(body)),
+		Hash:        fmt.Sprintf("%x", sha256.Sum256(body)),
+		URI:         ref.URI,
+	}, nil
+}
+
+type fileReader struct{}
+
+func (r *fileReader) Read(ctx context.Context, ref domain.ArtifactRef) (*domain.Artifact, error) {
+	select {
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	default:
+	}
+
+	if ref.URI == "" {
+		return nil, ErrMissingFilePath
+	}
+
+	return readFileArtifact(ref.URI)
+}
+
+func readFileArtifact(path string) (*domain.Artifact, error) {
+	file, err := os.Open(path)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read file %s: %w", path, err)
+	}
+	defer file.Close()
+
+	data, err := io.ReadAll(file)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read file %s: %w", path, err)
+	}
+
+	contentType := mime.TypeByExtension(filepath.Ext(path))
+	if contentType == "" {
+		contentType = defaults.ContentTypeTextPlain
+	}
+
+	return &domain.Artifact{
+		Name:        filepath.Base(path),
+		ContentType: contentType,
+		Body:        data,
+		URI:         path,
+		Size:        int64(len(data)),
+		Hash:        fmt.Sprintf("%x", sha256.Sum256(data)),
+	}, nil
+}

internal/artifact/reader_test.go

@@ -0,0 +1,180 @@
+package artifact
+
+import (
+	"context"
+	"errors"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
+)
+
+func TestCompositeReader_Read(t *testing.T) {
+	reader := NewCompositeReader()
+	ctx := context.Background()
+
+	t.Run("inline artifact", func(t *testing.T) {
+		ref := domain.ArtifactRef{
+			Type: domain.ArtifactRefInline,
+			Body: "hello world",
+		}
+		art, err := reader.Read(ctx, ref)
+		if err != nil {
+			t.Fatalf("unexpected error: %v", err)
+		}
+		if string(art.Body) != "hello world" {
+			t.Errorf("expected 'hello world', got %s", string(art.Body))
+		}
+		if art.ContentType != "text/plain" {
+			t.Errorf("expected text/plain content type, got %q", art.ContentType)
+		}
+		if art.Hash != "b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9" {
+			t.Errorf("unexpected hash: %s", art.Hash)
+		}
+		if art.Size != int64(len(ref.Body)) {
+			t.Errorf("expected size %d, got %d", len(ref.Body), art.Size)
+		}
+	})
+
+	t.Run("inline artifact missing body", func(t *testing.T) {
+		ref := domain.ArtifactRef{
+			Type: domain.ArtifactRefInline,
+			Body: "",
+		}
+		_, err := reader.Read(ctx, ref)
+		if !errors.Is(err, ErrMissingInlineBody) {
+			t.Errorf("expected ErrMissingInlineBody, got %v", err)
+		}
+	})
+
+	t.Run("unsupported ref type", func(t *testing.T) {
+		ref := domain.ArtifactRef{
+			Type: domain.ArtifactRefType("unsupported"),
+			URI:  "unsupported://bucket/key",
+		}
+		_, err := reader.Read(ctx, ref)
+		if !errors.Is(err, ErrUnsupportedRefType) {
+			t.Error("expected error for unsupported type")
+		}
+	})
+}
+
+func TestCompositeReaderCopiesInlineData(t *testing.T) {
+	reader := NewCompositeReader()
+	ref := domain.ArtifactRef{
+		Type: domain.ArtifactRefInline,
+		Body: "hello",
+		URI:  "inline:greeting",
+	}
+
+	first, err := reader.Read(context.Background(), ref)
+	if err != nil {
+		t.Fatalf("read first artifact: %v", err)
+	}
+	first.Body[0] = 'j'
+
+	second, err := reader.Read(context.Background(), ref)
+	if err != nil {
+		t.Fatalf("read second artifact: %v", err)
+	}
+	if got := string(second.Body); got != ref.Body {
+		t.Fatalf("expected an independent body %q, got %q", ref.Body, got)
+	}
+	if second.URI != ref.URI {
+		t.Fatalf("expected URI %q, got %q", ref.URI, second.URI)
+	}
+}
+
+func TestCompositeReaderHonorsCancellation(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	_, err := NewCompositeReader().Read(ctx, domain.ArtifactRef{
+		Type: domain.ArtifactRefInline,
+		Body: "ignored",
+	})
+	if !errors.Is(err, context.Canceled) {
+		t.Fatalf("expected context cancellation, got %v", err)
+	}
+}
+
+func TestFileReader_Read(t *testing.T) {
+	content := []byte("test file content")
+	filePath := filepath.Join(t.TempDir(), "artifact.txt")
+	if err := os.WriteFile(filePath, content, 0o600); err != nil {
+		t.Fatal(err)
+	}
+
+	reader := NewCompositeReader()
+	ctx := context.Background()
+
+	t.Run("file artifact loading", func(t *testing.T) {
+		ref := domain.ArtifactRef{
+			Type: domain.ArtifactRefFile,
+			URI:  filePath,
+		}
+		art, err := reader.Read(ctx, ref)
+		if err != nil {
+			t.Fatalf("unexpected error: %v", err)
+		}
+		if string(art.Body) != string(content) {
+			t.Errorf("expected %s, got %s", string(content), string(art.Body))
+		}
+		if art.Name != filepath.Base(filePath) {
+			t.Errorf("expected name %q, got %q", filepath.Base(filePath), art.Name)
+		}
+		if !strings.HasPrefix(art.ContentType, "text/plain") {
+			t.Errorf("expected text content type, got %q", art.ContentType)
+		}
+		if art.URI != filePath {
+			t.Errorf("expected URI %q, got %q", filePath, art.URI)
+		}
+		if art.Size != int64(len(content)) {
+			t.Errorf("expected size %d, got %d", len(content), art.Size)
+		}
+		if art.Hash != "60f5237ed4049f0382661ef009d2bc42e48c3ceb3edb6600f7024e7ab3b838f3" {
+			t.Errorf("unexpected hash: %s", art.Hash)
+		}
+	})
+
+	t.Run("missing file path", func(t *testing.T) {
+		ref := domain.ArtifactRef{
+			Type: domain.ArtifactRefFile,
+			URI:  "",
+		}
+		_, err := reader.Read(ctx, ref)
+		if !errors.Is(err, ErrMissingFilePath) {
+			t.Errorf("expected ErrMissingFilePath, got %v", err)
+		}
+	})
+
+	t.Run("missing file", func(t *testing.T) {
+		ref := domain.ArtifactRef{
+			Type: domain.ArtifactRefFile,
+			URI:  filepath.Join(t.TempDir(), "missing.txt"),
+		}
+		if _, err := reader.Read(ctx, ref); err == nil {
+			t.Fatal("expected missing file error")
+		}
+	})
+
+	t.Run("unknown extension uses text fallback", func(t *testing.T) {
+		path := filepath.Join(t.TempDir(), "artifact.unknownextension")
+		if err := os.WriteFile(path, content, 0o600); err != nil {
+			t.Fatal(err)
+		}
+
+		art, err := reader.Read(ctx, domain.ArtifactRef{
+			Type: domain.ArtifactRefFile,
+			URI:  path,
+		})
+		if err != nil {
+			t.Fatalf("unexpected error: %v", err)
+		}
+		if art.ContentType != "text/plain" {
+			t.Errorf("expected text/plain fallback, got %q", art.ContentType)
+		}
+	})
+}

internal/validate/standard_validator.go

@@ -0,0 +1,292 @@
+package validate
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io/fs"
+	"os"
+	"path"
+	"path/filepath"
+	"strings"
+
+	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
+	"gitea.maximumdirect.net/eric/promptkit/internal/filecatalog"
+	"github.com/santhosh-tekuri/jsonschema/v6"
+)
+
+// StandardValidator provides basic, JSON, and JSON Schema output validation.
+type StandardValidator struct {
+	schemaBaseDir string
+}
+
+type FSValidator struct {
+	fsys fs.FS
+	root string
+}
+
+func NewStandardValidator(schemaBaseDir string) Validator {
+	return &StandardValidator{schemaBaseDir: schemaBaseDir}
+}
+
+func NewFSValidator(fsys fs.FS, root string) Validator {
+	return &FSValidator{fsys: fsys, root: root}
+}
+
+func (v *StandardValidator) Validate(ctx context.Context, artifact *domain.Artifact, contract domain.OutputContract) (domain.ValidationResult, error) {
+	return validateArtifact(ctx, artifact, contract, v.validateJSONSchema)
+}
+
+func (v *FSValidator) Validate(ctx context.Context, artifact *domain.Artifact, contract domain.OutputContract) (domain.ValidationResult, error) {
+	return validateArtifact(ctx, artifact, contract, v.validateJSONSchema)
+}
+
+type schemaValidatorFunc func(instance any, schemaPath string) ([]string, error)
+
+func validateArtifact(ctx context.Context, artifact *domain.Artifact, contract domain.OutputContract, validateSchema schemaValidatorFunc) (domain.ValidationResult, error) {
+	select {
+	case <-ctx.Done():
+		return domain.ValidationResult{}, ctx.Err()
+	default:
+	}
+
+	res := domain.ValidationResult{
+		Mode:           contract.ValidationMode,
+		SchemaPath:     contract.SchemaPath,
+		RepairAttempts: contract.RepairAttempts,
+	}
+
+	if artifact == nil {
+		return domain.ValidationResult{}, errors.New("artifact is required for validation")
+	}
+
+	switch contract.ValidationMode {
+	case domain.ValidationNone:
+		res.Status = domain.ValidationSkipped
+		res.IsValid = true
+		return res, nil
+	case domain.ValidationBasic:
+		if strings.TrimSpace(string(artifact.Body)) == "" {
+			res.Status = domain.ValidationFailed
+			res.IsValid = false
+			res.Errors = []string{"output is empty"}
+			return res, nil
+		}
+		res.Status = domain.ValidationPassed
+		res.IsValid = true
+		return res, nil
+	case domain.ValidationJSON:
+		_, jsonErr := parseJSON(artifact.Body)
+		if jsonErr != nil {
+			res.Status = domain.ValidationFailed
+			res.IsValid = false
+			res.Errors = []string{fmt.Sprintf("invalid JSON: %v", jsonErr)}
+			return res, nil
+		}
+		res.Status = domain.ValidationPassed
+		res.IsValid = true
+		return res, nil
+	case domain.ValidationJSONSchema:
+		instance, jsonErr := parseJSON(artifact.Body)
+		if jsonErr != nil {
+			res.Status = domain.ValidationFailed
+			res.IsValid = false
+			res.Errors = []string{fmt.Sprintf("invalid JSON: %v", jsonErr)}
+			return res, nil
+		}
+
+		validationErrors, err := validateSchema(instance, contract.SchemaPath)
+		if err != nil {
+			return domain.ValidationResult{}, err
+		}
+		if len(validationErrors) > 0 {
+			res.Status = domain.ValidationFailed
+			res.IsValid = false
+			res.Errors = validationErrors
+			return res, nil
+		}
+
+		res.Status = domain.ValidationPassed
+		res.IsValid = true
+		return res, nil
+	default:
+		return domain.ValidationResult{}, fmt.Errorf("unsupported validation mode: %q", contract.ValidationMode)
+	}
+}
+
+func (v *StandardValidator) validateJSONSchema(instance any, schemaPath string) ([]string, error) {
+	resolvedSchemaPath, err := v.resolveSchemaPath(schemaPath)
+	if err != nil {
+		return nil, err
+	}
+
+	compiler := jsonschema.NewCompiler()
+	schema, err := compiler.Compile(resolvedSchemaPath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to compile JSON schema %q: %w", resolvedSchemaPath, err)
+	}
+
+	if err := schema.Validate(instance); err != nil {
+		return []string{fmt.Sprintf("json schema validation failed: %v", err)}, nil
+	}
+	return nil, nil
+}
+
+func (v *FSValidator) validateJSONSchema(instance any, schemaPath string) ([]string, error) {
+	schemaName, schemaDoc, err := v.loadSchemaDocument(schemaPath)
+	if err != nil {
+		return nil, err
+	}
+
+	resourceURL := fsSchemaResourceURL(schemaName)
+	compiler := jsonschema.NewCompiler()
+	if err := compiler.AddResource(resourceURL, schemaDoc); err != nil {
+		return nil, fmt.Errorf("failed to register JSON schema %q: %w", schemaName, err)
+	}
+	schema, err := compiler.Compile(resourceURL)
+	if err != nil {
+		return nil, fmt.Errorf("failed to compile JSON schema %q: %w", schemaName, err)
+	}
+
+	if err := schema.Validate(instance); err != nil {
+		return []string{fmt.Sprintf("json schema validation failed: %v", err)}, nil
+	}
+	return nil, nil
+}
+
+func parseJSON(body []byte) (any, error) {
+	var v any
+	if err := json.Unmarshal(body, &v); err != nil {
+		return nil, err
+	}
+	return v, nil
+}
+
+func (v *StandardValidator) LoadSchemaDocument(ctx context.Context, schemaPath string) (any, error) {
+	select {
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	default:
+	}
+
+	resolved, err := v.resolveSchemaPath(schemaPath)
+	if err != nil {
+		return nil, err
+	}
+
+	raw, err := os.ReadFile(resolved)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read schema file %q: %w", resolved, err)
+	}
+
+	var doc any
+	if err := json.Unmarshal(raw, &doc); err != nil {
+		return nil, fmt.Errorf("failed to decode JSON schema %q: %w", resolved, err)
+	}
+	return doc, nil
+}
+
+func (v *FSValidator) LoadSchemaDocument(ctx context.Context, schemaPath string) (any, error) {
+	select {
+	case <-ctx.Done():
+		return nil, ctx.Err()
+	default:
+	}
+
+	_, doc, err := v.loadSchemaDocument(schemaPath)
+	if err != nil {
+		return nil, err
+	}
+	return doc, nil
+}
+
+func (v *StandardValidator) resolveSchemaPath(schemaPath string) (string, error) {
+	if strings.TrimSpace(schemaPath) == "" {
+		return "", errors.New("schema path is required for json_schema validation")
+	}
+
+	resolved := schemaPath
+	if !filepath.IsAbs(schemaPath) {
+		resolved = filepath.Join(v.schemaBaseDir, schemaPath)
+	}
+
+	resolved = filepath.Clean(resolved)
+	if _, err := os.Stat(resolved); err != nil {
+		return "", fmt.Errorf("failed to access schema file %q: %w", resolved, err)
+	}
+
+	return resolved, nil
+}
+
+func (v *FSValidator) loadSchemaDocument(schemaPath string) (string, any, error) {
+	resolved, err := v.resolveSchemaPath(schemaPath)
+	if err != nil {
+		return "", nil, err
+	}
+
+	raw, err := fs.ReadFile(v.fsys, resolved)
+	if err != nil {
+		return "", nil, fmt.Errorf("failed to read schema file %q: %w", resolved, err)
+	}
+
+	var doc any
+	if err := json.Unmarshal(raw, &doc); err != nil {
+		return "", nil, fmt.Errorf("failed to decode JSON schema %q: %w", resolved, err)
+	}
+	return resolved, doc, nil
+}
+
+func (v *FSValidator) resolveSchemaPath(schemaPath string) (string, error) {
+	if strings.TrimSpace(schemaPath) == "" {
+		return "", errors.New("schema path is required for json_schema validation")
+	}
+	if v.fsys == nil {
+		return "", errors.New("schema filesystem is nil")
+	}
+
+	cleanRoot := filecatalog.CleanFSRoot(v.root)
+	rootInfo, err := fs.Stat(v.fsys, cleanRoot)
+	if err != nil {
+		return "", fmt.Errorf("failed to access schema source %q: %w", cleanRoot, err)
+	}
+
+	var resolved string
+	if rootInfo.IsDir() {
+		resolvedPath, _, err := filecatalog.ResolveFSPath(cleanRoot, cleanRoot, schemaPath)
+		if err != nil {
+			return "", err
+		}
+		resolved = resolvedPath
+	} else {
+		cleanSchemaPath, err := cleanSchemaFSPath(schemaPath)
+		if err != nil {
+			return "", err
+		}
+		if cleanSchemaPath != path.Base(cleanRoot) {
+			return "", fmt.Errorf("schema path %q does not match schema file %q", cleanSchemaPath, path.Base(cleanRoot))
+		}
+		resolved = cleanRoot
+	}
+
+	if _, err := fs.Stat(v.fsys, resolved); err != nil {
+		return "", fmt.Errorf("failed to access schema file %q: %w", resolved, err)
+	}
+	return resolved, nil
+}
+
+func cleanSchemaFSPath(schemaPath string) (string, error) {
+	cleaned := strings.TrimSpace(schemaPath)
+	if cleaned == "" {
+		return "", errors.New("schema path is required for json_schema validation")
+	}
+	cleaned = path.Clean(cleaned)
+	if path.IsAbs(cleaned) {
+		return "", fmt.Errorf("schema path %q must be relative", schemaPath)
+	}
+	return cleaned, nil
+}
+
+func fsSchemaResourceURL(schemaName string) string {
+	return "promptkit-schema:///" + strings.TrimPrefix(path.Clean(schemaName), "/")
+}

internal/validate/standard_validator_test.go

@@ -0,0 +1,413 @@
+package validate
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+	"testing/fstest"
+
+	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
+)
+
+func TestStandardValidatorNoneSkipped(t *testing.T) {
+	v := NewStandardValidator("")
+
+	res, err := v.Validate(context.Background(), &domain.Artifact{Body: []byte("ignored")}, domain.OutputContract{
+		ValidationMode: domain.ValidationNone,
+	})
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+	if res.Status != domain.ValidationSkipped {
+		t.Fatalf("expected skipped, got %q", res.Status)
+	}
+	if !res.IsValid {
+		t.Fatal("expected valid=true for skipped")
+	}
+}
+
+func TestStandardValidatorBasicSuccess(t *testing.T) {
+	v := NewStandardValidator("")
+
+	res, err := v.Validate(context.Background(), &domain.Artifact{Body: []byte("hello")}, domain.OutputContract{
+		ValidationMode: domain.ValidationBasic,
+	})
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+	if res.Status != domain.ValidationPassed || !res.IsValid {
+		t.Fatalf("expected passed/valid, got status=%q valid=%v", res.Status, res.IsValid)
+	}
+}
+
+func TestStandardValidatorBasicFailureEmpty(t *testing.T) {
+	v := NewStandardValidator("")
+
+	res, err := v.Validate(context.Background(), &domain.Artifact{Body: []byte("  \n\t  ")}, domain.OutputContract{
+		ValidationMode: domain.ValidationBasic,
+	})
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+	if res.Status != domain.ValidationFailed || res.IsValid {
+		t.Fatalf("expected failed/invalid, got status=%q valid=%v", res.Status, res.IsValid)
+	}
+	if len(res.Errors) == 0 {
+		t.Fatal("expected validation errors")
+	}
+}
+
+func TestStandardValidatorJSONSuccess(t *testing.T) {
+	v := NewStandardValidator("")
+
+	res, err := v.Validate(context.Background(), &domain.Artifact{Body: []byte(`{"ok":true}`)}, domain.OutputContract{
+		ValidationMode: domain.ValidationJSON,
+	})
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+	if res.Status != domain.ValidationPassed || !res.IsValid {
+		t.Fatalf("expected passed/valid, got status=%q valid=%v", res.Status, res.IsValid)
+	}
+}
+
+func TestStandardValidatorJSONFailure(t *testing.T) {
+	v := NewStandardValidator("")
+
+	res, err := v.Validate(context.Background(), &domain.Artifact{Body: []byte(`{"ok":`)}, domain.OutputContract{
+		ValidationMode: domain.ValidationJSON,
+	})
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+	if res.Status != domain.ValidationFailed || res.IsValid {
+		t.Fatalf("expected failed/invalid, got status=%q valid=%v", res.Status, res.IsValid)
+	}
+	if len(res.Errors) == 0 {
+		t.Fatal("expected parse errors")
+	}
+}
+
+func TestStandardValidatorJSONSchemaSuccess(t *testing.T) {
+	tmp := t.TempDir()
+	schemaPath := filepath.Join(tmp, "schema.json")
+	if err := os.WriteFile(schemaPath, []byte(`{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "type": "object",
+  "required": ["name"],
+  "properties": {
+    "name": {"type": "string"}
+  }
+}`), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	v := NewStandardValidator(tmp)
+
+	res, err := v.Validate(context.Background(), &domain.Artifact{Body: []byte(`{"name":"eris"}`)}, domain.OutputContract{
+		ValidationMode: domain.ValidationJSONSchema,
+		SchemaPath:     "schema.json",
+	})
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+	if res.Status != domain.ValidationPassed || !res.IsValid {
+		t.Fatalf("expected passed/valid, got status=%q valid=%v", res.Status, res.IsValid)
+	}
+}
+
+func TestStandardValidatorJSONSchemaNestedSchemaPathSuccess(t *testing.T) {
+	tmp := t.TempDir()
+	nestedDir := filepath.Join(tmp, "dnd")
+	if err := os.MkdirAll(nestedDir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(nestedDir, "schema.json"), []byte(`{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "type": "object",
+  "required": ["name"],
+  "properties": {
+    "name": {"type": "string"}
+  }
+}`), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	v := NewStandardValidator(tmp)
+
+	res, err := v.Validate(context.Background(), &domain.Artifact{Body: []byte(`{"name":"eris"}`)}, domain.OutputContract{
+		ValidationMode: domain.ValidationJSONSchema,
+		SchemaPath:     filepath.Join("dnd", "schema.json"),
+	})
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+	if res.Status != domain.ValidationPassed || !res.IsValid {
+		t.Fatalf("expected passed/valid, got status=%q valid=%v", res.Status, res.IsValid)
+	}
+}
+
+func TestStandardValidatorJSONSchemaNestedSchemaPathMissing(t *testing.T) {
+	v := NewStandardValidator(t.TempDir())
+
+	_, err := v.Validate(context.Background(), &domain.Artifact{Body: []byte(`{"name":"eris"}`)}, domain.OutputContract{
+		ValidationMode: domain.ValidationJSONSchema,
+		SchemaPath:     filepath.Join("dnd", "missing.json"),
+	})
+	if err == nil {
+		t.Fatal("expected nested schema load error")
+	}
+}
+
+func TestStandardValidatorJSONSchemaFailure(t *testing.T) {
+	tmp := t.TempDir()
+	schemaPath := filepath.Join(tmp, "schema.json")
+	if err := os.WriteFile(schemaPath, []byte(`{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "type": "object",
+  "required": ["name"],
+  "properties": {
+    "name": {"type": "string"}
+  }
+}`), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	v := NewStandardValidator(tmp)
+
+	res, err := v.Validate(context.Background(), &domain.Artifact{Body: []byte(`{"count":1}`)}, domain.OutputContract{
+		ValidationMode: domain.ValidationJSONSchema,
+		SchemaPath:     "schema.json",
+	})
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+	if res.Status != domain.ValidationFailed || res.IsValid {
+		t.Fatalf("expected failed/invalid, got status=%q valid=%v", res.Status, res.IsValid)
+	}
+	if len(res.Errors) == 0 {
+		t.Fatal("expected schema errors")
+	}
+}
+
+func TestStandardValidatorJSONSchemaSchemaLoadError(t *testing.T) {
+	v := NewStandardValidator(t.TempDir())
+
+	_, err := v.Validate(context.Background(), &domain.Artifact{Body: []byte(`{"name":"eris"}`)}, domain.OutputContract{
+		ValidationMode: domain.ValidationJSONSchema,
+		SchemaPath:     "missing.json",
+	})
+	if err == nil {
+		t.Fatal("expected schema load error")
+	}
+}
+
+func TestStandardValidatorJSONSchemaCompilationError(t *testing.T) {
+	tmp := t.TempDir()
+	if err := os.WriteFile(filepath.Join(tmp, "schema.json"), []byte(`{"type":42}`), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	v := NewStandardValidator(tmp)
+
+	res, err := v.Validate(context.Background(), &domain.Artifact{Body: []byte(`{}`)}, domain.OutputContract{
+		ValidationMode: domain.ValidationJSONSchema,
+		SchemaPath:     "schema.json",
+	})
+	if err == nil || !strings.Contains(err.Error(), "failed to compile JSON schema") {
+		t.Fatalf("expected schema compilation error, got result=%#v error=%v", res, err)
+	}
+}
+
+func TestStandardValidatorLoadSchemaDocumentSuccess(t *testing.T) {
+	tmp := t.TempDir()
+	if err := os.WriteFile(filepath.Join(tmp, "schema.json"), []byte(`{
+  "type": "object",
+  "properties": {
+    "name": {"type": "string"}
+  }
+}`), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	v := NewStandardValidator(tmp)
+	loader, ok := v.(SchemaDocumentLoader)
+	if !ok {
+		t.Fatal("standard validator must implement SchemaDocumentLoader")
+	}
+
+	doc, err := loader.LoadSchemaDocument(context.Background(), "schema.json")
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+
+	obj, ok := doc.(map[string]any)
+	if !ok {
+		t.Fatalf("expected object document, got %#v", doc)
+	}
+	if obj["type"] != "object" {
+		t.Fatalf("expected schema type=object, got %#v", obj["type"])
+	}
+}
+
+func TestStandardValidatorLoadSchemaDocumentInvalidJSON(t *testing.T) {
+	tmp := t.TempDir()
+	if err := os.WriteFile(filepath.Join(tmp, "schema.json"), []byte(`{`), 0644); err != nil {
+		t.Fatal(err)
+	}
+
+	v := NewStandardValidator(tmp)
+	loader, ok := v.(SchemaDocumentLoader)
+	if !ok {
+		t.Fatal("standard validator must implement SchemaDocumentLoader")
+	}
+
+	_, err := loader.LoadSchemaDocument(context.Background(), "schema.json")
+	if err == nil {
+		t.Fatal("expected decode error")
+	}
+}
+
+func TestFSValidatorJSONSchemaSuccess(t *testing.T) {
+	v := NewFSValidator(fstest.MapFS{
+		"schemas/events.schema.json": &fstest.MapFile{Data: []byte(`{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "type": "object",
+  "required": ["events"],
+  "properties": {
+    "events": {"type": "array"}
+  }
+}`)},
+	}, "schemas")
+
+	res, err := v.Validate(context.Background(), &domain.Artifact{Body: []byte(`{"events":[]}`)}, domain.OutputContract{
+		ValidationMode: domain.ValidationJSONSchema,
+		SchemaPath:     "events.schema.json",
+	})
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+	if res.Status != domain.ValidationPassed || !res.IsValid {
+		t.Fatalf("expected passed/valid, got status=%q valid=%v", res.Status, res.IsValid)
+	}
+}
+
+func TestFSValidatorJSONSchemaRegistrationError(t *testing.T) {
+	v := NewFSValidator(fstest.MapFS{
+		"schemas/%zz.json": &fstest.MapFile{Data: []byte(`{"type":"object"}`)},
+	}, "schemas")
+
+	res, err := v.Validate(context.Background(), &domain.Artifact{Body: []byte(`{}`)}, domain.OutputContract{
+		ValidationMode: domain.ValidationJSONSchema,
+		SchemaPath:     "%zz.json",
+	})
+	if err == nil || !strings.Contains(err.Error(), "failed to register JSON schema") {
+		t.Fatalf("expected schema registration error, got result=%#v error=%v", res, err)
+	}
+}
+
+func TestFSValidatorJSONSchemaPathContainment(t *testing.T) {
+	t.Run("nested schema inside root succeeds", func(t *testing.T) {
+		v := NewFSValidator(fstest.MapFS{
+			"schemas/nested/events.schema.json": &fstest.MapFile{Data: []byte(`{
+  "type": "object",
+  "required": ["events"],
+  "properties": {
+    "events": {"type": "array"}
+  }
+}`)},
+		}, "schemas")
+
+		res, err := v.Validate(context.Background(), &domain.Artifact{Body: []byte(`{"events":[]}`)}, domain.OutputContract{
+			ValidationMode: domain.ValidationJSONSchema,
+			SchemaPath:     "nested/events.schema.json",
+		})
+		if err != nil {
+			t.Fatalf("expected no error, got %v", err)
+		}
+		if res.Status != domain.ValidationPassed || !res.IsValid {
+			t.Fatalf("expected passed/valid, got status=%q valid=%v", res.Status, res.IsValid)
+		}
+	})
+
+	tests := []struct {
+		name       string
+		schemaPath string
+		wantErr    string
+	}{
+		{name: "parent escape rejected", schemaPath: "../outside.schema.json", wantErr: "escapes source root"},
+		{name: "absolute path rejected", schemaPath: "/outside.schema.json", wantErr: "must be relative"},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			v := NewFSValidator(fstest.MapFS{
+				"schemas/events.schema.json":  &fstest.MapFile{Data: []byte(`{"type":"object"}`)},
+				"outside.schema.json":         &fstest.MapFile{Data: []byte(`{"type":"object"}`)},
+				"schemas/outside.schema.json": &fstest.MapFile{Data: []byte(`{"type":"object"}`)},
+			}, "schemas")
+
+			_, err := v.Validate(context.Background(), &domain.Artifact{Body: []byte(`{"events":[]}`)}, domain.OutputContract{
+				ValidationMode: domain.ValidationJSONSchema,
+				SchemaPath:     tc.schemaPath,
+			})
+			if err == nil {
+				t.Fatal("expected schema path error")
+			}
+			if !strings.Contains(err.Error(), tc.wantErr) {
+				t.Fatalf("expected error to contain %q, got %v", tc.wantErr, err)
+			}
+		})
+	}
+}
+
+func TestFSValidatorSingleSchemaFileUsesBaseName(t *testing.T) {
+	v := NewFSValidator(fstest.MapFS{
+		"events.schema.json": &fstest.MapFile{Data: []byte(`{
+  "type": "object",
+  "required": ["events"],
+  "properties": {
+    "events": {"type": "array"}
+  }
+}`)},
+	}, "events.schema.json")
+
+	res, err := v.Validate(context.Background(), &domain.Artifact{Body: []byte(`{"events":[]}`)}, domain.OutputContract{
+		ValidationMode: domain.ValidationJSONSchema,
+		SchemaPath:     "events.schema.json",
+	})
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+	if res.Status != domain.ValidationPassed || !res.IsValid {
+		t.Fatalf("expected passed/valid, got status=%q valid=%v", res.Status, res.IsValid)
+	}
+
+	_, err = v.Validate(context.Background(), &domain.Artifact{Body: []byte(`{"events":[]}`)}, domain.OutputContract{
+		ValidationMode: domain.ValidationJSONSchema,
+		SchemaPath:     "other.schema.json",
+	})
+	if err == nil {
+		t.Fatal("expected schema path mismatch error")
+	}
+}
+
+func TestFSValidatorLoadSchemaDocument(t *testing.T) {
+	v := NewFSValidator(fstest.MapFS{
+		"schemas/schema.json": &fstest.MapFile{Data: []byte(`{"type":"object"}`)},
+	}, "schemas")
+	loader, ok := v.(SchemaDocumentLoader)
+	if !ok {
+		t.Fatal("fs validator must implement SchemaDocumentLoader")
+	}
+
+	doc, err := loader.LoadSchemaDocument(context.Background(), "schema.json")
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+	obj, ok := doc.(map[string]any)
+	if !ok || obj["type"] != "object" {
+		t.Fatalf("unexpected schema document: %#v", doc)
+	}
+}

internal/validate/validator.go

@@ -0,0 +1,16 @@
+package validate
+
+import (
+	"context"
+	"gitea.maximumdirect.net/eric/promptkit/internal/domain"
+)
+
+// Validator validates the generated artifact based on the output contract.
+type Validator interface {
+	Validate(ctx context.Context, artifact *domain.Artifact, contract domain.OutputContract) (domain.ValidationResult, error)
+}
+
+// SchemaDocumentLoader loads JSON schema documents using validator path semantics.
+type SchemaDocumentLoader interface {
+	LoadSchemaDocument(ctx context.Context, schemaPath string) (any, error)
+}