Add artifact reading and output validation

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)
+}