Add reference contracts to extractor metadata

internal/framework/pipeline/module.go

@@ -4,6 +4,8 @@ import (
 	"fmt"
 	"sort"
 	"strings"
+
+	"gitea.maximumdirect.net/eric/notarius/internal/framework/contracts"
 )
 
 type ModuleStage string
@@ -19,10 +21,11 @@ const (
 )
 
 type ModuleSpec struct {
-	Key      string
-	Stage    ModuleStage
-	Provides []string
-	Requires []string
+	Key            string
+	Stage          ModuleStage
+	Provides       []string
+	Requires       []string
+	ReferenceSlots []contracts.ReferenceSlot
 }
 
 func defaultModuleSpec(key string, stage ModuleStage) ModuleSpec {
@@ -34,10 +37,11 @@ func defaultModuleSpec(key string, stage ModuleStage) ModuleSpec {
 
 func normalizeModuleSpec(spec ModuleSpec) ModuleSpec {
 	return ModuleSpec{
-		Key:      strings.TrimSpace(spec.Key),
-		Stage:    spec.Stage,
-		Provides: normalizeCapabilities(spec.Provides),
-		Requires: normalizeCapabilities(spec.Requires),
+		Key:            strings.TrimSpace(spec.Key),
+		Stage:          spec.Stage,
+		Provides:       normalizeCapabilities(spec.Provides),
+		Requires:       normalizeCapabilities(spec.Requires),
+		ReferenceSlots: normalizeReferenceSlots(spec.ReferenceSlots),
 	}
 }
 
@@ -68,10 +72,11 @@ func normalizeCapabilities(values []string) []string {
 
 func cloneModuleSpec(spec ModuleSpec) ModuleSpec {
 	return ModuleSpec{
-		Key:      spec.Key,
-		Stage:    spec.Stage,
-		Provides: append([]string(nil), spec.Provides...),
-		Requires: append([]string(nil), spec.Requires...),
+		Key:            spec.Key,
+		Stage:          spec.Stage,
+		Provides:       append([]string(nil), spec.Provides...),
+		Requires:       append([]string(nil), spec.Requires...),
+		ReferenceSlots: cloneReferenceSlots(spec.ReferenceSlots),
 	}
 }
 
@@ -82,6 +87,12 @@ func validateModuleSpec(kind string, expectedStage ModuleStage, spec ModuleSpec)
 	if spec.Stage != expectedStage {
 		return fmt.Errorf("%s %q must use %q stage, got %q", kind, spec.Key, expectedStage, spec.Stage)
 	}
+	if spec.Stage != StageExtract && len(spec.ReferenceSlots) > 0 {
+		return fmt.Errorf("%s %q must not declare reference slots", kind, spec.Key)
+	}
+	if err := validateReferenceSlots(spec.ReferenceSlots); err != nil {
+		return fmt.Errorf("%s %q reference slots: %w", kind, spec.Key, err)
+	}
 	return nil
 }
 
@@ -97,3 +108,74 @@ func sortedRegistryKeys[C any](constructors map[string]C) []string {
 	sort.Strings(keys)
 	return keys
 }
+
+func normalizeReferenceSlots(slots []contracts.ReferenceSlot) []contracts.ReferenceSlot {
+	if len(slots) == 0 {
+		return nil
+	}
+
+	normalized := make([]contracts.ReferenceSlot, 0, len(slots))
+	for _, slot := range slots {
+		slot.Name = strings.TrimSpace(slot.Name)
+		slot.Description = strings.TrimSpace(slot.Description)
+		slot.AcceptedMediaTypes = normalizeStringSet(slot.AcceptedMediaTypes)
+		normalized = append(normalized, slot)
+	}
+	sort.SliceStable(normalized, func(i, j int) bool {
+		return normalized[i].Name < normalized[j].Name
+	})
+	return normalized
+}
+
+func normalizeStringSet(values []string) []string {
+	if len(values) == 0 {
+		return nil
+	}
+	seen := make(map[string]struct{}, len(values))
+	for _, value := range values {
+		normalized := strings.TrimSpace(value)
+		if normalized == "" {
+			continue
+		}
+		seen[normalized] = struct{}{}
+	}
+	if len(seen) == 0 {
+		return nil
+	}
+
+	out := make([]string, 0, len(seen))
+	for value := range seen {
+		out = append(out, value)
+	}
+	sort.Strings(out)
+	return out
+}
+
+func validateReferenceSlots(slots []contracts.ReferenceSlot) error {
+	seen := make(map[string]struct{}, len(slots))
+	for i, slot := range slots {
+		if slot.Name == "" {
+			return fmt.Errorf("slot[%d].name must not be empty", i)
+		}
+		if _, ok := seen[slot.Name]; ok {
+			return fmt.Errorf("slot name %q is duplicated", slot.Name)
+		}
+		seen[slot.Name] = struct{}{}
+		if slot.MaxBytes < 0 {
+			return fmt.Errorf("slot %q max_bytes must not be negative", slot.Name)
+		}
+	}
+	return nil
+}
+
+func cloneReferenceSlots(slots []contracts.ReferenceSlot) []contracts.ReferenceSlot {
+	if len(slots) == 0 {
+		return nil
+	}
+	out := make([]contracts.ReferenceSlot, 0, len(slots))
+	for _, slot := range slots {
+		slot.AcceptedMediaTypes = append([]string(nil), slot.AcceptedMediaTypes...)
+		out = append(out, slot)
+	}
+	return out
+}