Added support for OpenAI-compatible structured output

internal/usecase/runner.go

@@ -11,6 +11,7 @@ import (
 	"os"
 	"strings"
 	"time"
+	"unicode"
 
 	"gitea.maximumdirect.net/eric/scriptorium/internal/artifact"
 	"gitea.maximumdirect.net/eric/scriptorium/internal/defaults"
@@ -87,8 +88,9 @@ func (r *Runner) Run(ctx context.Context, req domain.RunRequest) (*domain.RunRes
 	}
 
 	genResp, err := r.llm.Generate(ctx, domain.GenerateRequest{
-		Prompt: domain.RenderedPrompt{Messages: prepared.Messages},
-		Target: prepared.EffectiveModelParams,
+		Prompt:           domain.RenderedPrompt{Messages: prepared.Messages},
+		Target:           prepared.EffectiveModelParams,
+		StructuredOutput: prepared.StructuredOutput,
 	})
 	if err != nil {
 		return nil, fmt.Errorf("%w: %w", ErrLLMGenerate, err)
@@ -109,6 +111,7 @@ func (r *Runner) Run(ctx context.Context, req domain.RunRequest) (*domain.RunRes
 				PreviousOutput:   genResp.Content,
 				ValidationErrors: validationResult.Errors,
 				Target:           prepared.EffectiveModelParams,
+				StructuredOutput: prepared.StructuredOutput,
 				Attempt:          attemptsUsed,
 				MaxAttempts:      prepared.OutputContract.RepairAttempts,
 				Mode:             prepared.OutputContract.ValidationMode,
@@ -194,6 +197,10 @@ func (r *Runner) Prepare(ctx context.Context, req domain.RunRequest) (*domain.Pr
 	}
 
 	effectiveContract := resolveOutputContract(def, req.Validation)
+	structuredOutput, err := r.resolveStructuredOutput(ctx, def, effectiveContract)
+	if err != nil {
+		return nil, err
+	}
 
 	resolvedInputs := make(map[string]*domain.Artifact, len(req.Inputs))
 	inputHashes := make(map[string]string, len(req.Inputs))
@@ -222,6 +229,7 @@ func (r *Runner) Prepare(ctx context.Context, req domain.RunRequest) (*domain.Pr
 		SelectedProfileID:    selectedProfileID,
 		EffectiveModelParams: effectiveModel,
 		OutputContract:       effectiveContract,
+		StructuredOutput:     structuredOutput,
 		InputHashes:          inputHashes,
 		RenderedPromptHash:   hashRenderedPrompt(*renderedPrompt),
 		Messages:             renderedPrompt.Messages,
@@ -231,6 +239,57 @@ func (r *Runner) Prepare(ctx context.Context, req domain.RunRequest) (*domain.Pr
 	}, nil
 }
 
+func (r *Runner) resolveStructuredOutput(ctx context.Context, def *domain.PromptDefinition, contract domain.OutputContract) (*domain.StructuredOutputSpec, error) {
+	if contract.ValidationMode != domain.ValidationJSONSchema {
+		return nil, nil
+	}
+
+	loader, ok := r.validator.(validate.SchemaDocumentLoader)
+	if !ok || loader == nil {
+		return nil, fmt.Errorf("%w: json_schema output requires schema document loader", ErrValidation)
+	}
+
+	schemaDoc, err := loader.LoadSchemaDocument(ctx, contract.SchemaPath)
+	if err != nil {
+		return nil, fmt.Errorf("%w: failed to load json schema for structured output: %v", ErrValidation, err)
+	}
+
+	return &domain.StructuredOutputSpec{
+		Type: domain.StructuredOutputJSONSchema,
+		JSONSchema: &domain.StructuredOutputJSONSpec{
+			Name:   deriveStructuredSchemaName(def.ID, def.Version),
+			Strict: true,
+			Schema: schemaDoc,
+		},
+	}, nil
+}
+
+func deriveStructuredSchemaName(promptID string, promptVersion string) string {
+	raw := strings.TrimSpace(promptID)
+	if v := strings.TrimSpace(promptVersion); v != "" {
+		if raw == "" {
+			raw = v
+		} else {
+			raw = raw + "_" + v
+		}
+	}
+
+	var b strings.Builder
+	for _, r := range raw {
+		if unicode.IsLetter(r) || unicode.IsDigit(r) || r == '_' || r == '-' {
+			b.WriteRune(r)
+		} else {
+			b.WriteRune('_')
+		}
+	}
+
+	name := strings.Trim(b.String(), "_-")
+	if name == "" {
+		return "scriptorium_schema"
+	}
+	return name
+}
+
 func (r *Runner) validateOutput(ctx context.Context, artifact *domain.Artifact, contract domain.OutputContract, attemptsUsed int) (domain.ValidationResult, error) {
 	if r.validator == nil || contract.ValidationMode == domain.ValidationNone {
 		return domain.ValidationResult{