Adopt registry-backed NPC occurrence artifacts

internal/modules/dnd/npcs/registry/registry.go

@@ -32,7 +32,9 @@ type Registry struct {
 	digest           string
 	projectionDigest string
 	promptInput      contracts.LLMInputMaterial
+	identityInput    contracts.LLMInputMaterial
 	lookupByKey      map[string]int
+	lookupByID       map[string]int
 }
 
 // Resolver selects and memoizes immutable NPC registry views.
@@ -109,7 +111,9 @@ func emptyRegistry() *Registry {
 		canonical:        append([]byte(nil), content...),
 		projectionDigest: projectionDigest,
 		promptInput:      contracts.NewLLMInputMaterial(ReferenceSlot, npccodec.MediaType, content, projectionDigest, ""),
+		identityInput:    contracts.NewLLMInputMaterial(ReferenceSlot, npccodec.MediaType, content, projectionDigest, ""),
 		lookupByKey:      map[string]int{},
+		lookupByID:       map[string]int{},
 	}
 }
 
@@ -129,8 +133,10 @@ func loadRegistry(referenceContent []byte) (*Registry, error) {
 
 	list := cloneNPCRegistry(value)
 	lookupByKey := make(map[string]int, len(list.NPCs))
+	lookupByID := make(map[string]int, len(list.NPCs))
 	for index, npc := range list.NPCs {
 		lookupByKey[identity.ComparisonKey(npc.Name)] = index
+		lookupByID[npc.ID] = index
 	}
 	digest := semanticDigest(content)
 	projection, err := nameProjection(list)
@@ -138,6 +144,11 @@ func loadRegistry(referenceContent []byte) (*Registry, error) {
 		return nil, fmt.Errorf("encode NPC name projection: %w", err)
 	}
 	projectionDigest := semanticDigest(projection)
+	identityProjection, err := identityProjection(list)
+	if err != nil {
+		return nil, fmt.Errorf("encode NPC identity projection: %w", err)
+	}
+	identityProjectionDigest := semanticDigest(identityProjection)
 	return &Registry{
 		bound:            true,
 		list:             list,
@@ -146,6 +157,8 @@ func loadRegistry(referenceContent []byte) (*Registry, error) {
 		projectionDigest: projectionDigest,
 		promptInput:      contracts.NewLLMInputMaterial(ReferenceSlot, npccodec.MediaType, projection, projectionDigest, ""),
 		lookupByKey:      lookupByKey,
+		identityInput:    contracts.NewLLMInputMaterial(ReferenceSlot, npccodec.MediaType, identityProjection, identityProjectionDigest, ""),
+		lookupByID:       lookupByID,
 	}, nil
 }
 
@@ -211,6 +224,15 @@ func (r *Registry) PromptInput() contracts.LLMInputMaterial {
 	return r.promptInput.Clone()
 }
 
+// IdentityPromptInput returns the ordered ID/name projection for consumers
+// that must bind output records to exact registry identities.
+func (r *Registry) IdentityPromptInput() contracts.LLMInputMaterial {
+	if r == nil {
+		return contracts.LLMInputMaterial{}
+	}
+	return r.identityInput.Clone()
+}
+
 // Lookup returns the canonical NPC for an exact canonical-name match under the
 // NPC identity comparison policy.
 func (r *Registry) Lookup(value string) (dnd.NPC, bool) {
@@ -224,6 +246,18 @@ func (r *Registry) Lookup(value string) (dnd.NPC, bool) {
 	return cloneNPC(r.list.NPCs[index]), true
 }
 
+// LookupID returns the canonical NPC for an exact durable ID.
+func (r *Registry) LookupID(value string) (dnd.NPC, bool) {
+	if r == nil {
+		return dnd.NPC{}, false
+	}
+	index, ok := r.lookupByID[value]
+	if !ok {
+		return dnd.NPC{}, false
+	}
+	return cloneNPC(r.list.NPCs[index]), true
+}
+
 func semanticDigest(content []byte) string {
 	sum := sha256.Sum256(content)
 	return "sha256:" + hex.EncodeToString(sum[:])
@@ -233,10 +267,19 @@ type projectedNPC struct {
 	Name string `json:"name"`
 }
 
+type identityProjectedNPC struct {
+	ID   string `json:"id"`
+	Name string `json:"name"`
+}
+
 type projectedNPCRegistry struct {
 	NPCs []projectedNPC `json:"npcs"`
 }
 
+type identityProjectedNPCRegistry struct {
+	NPCs []identityProjectedNPC `json:"npcs"`
+}
+
 func nameProjection(list dnd.NPCRegistry) ([]byte, error) {
 	projection := projectedNPCRegistry{NPCs: make([]projectedNPC, len(list.NPCs))}
 	for index, npc := range list.NPCs {
@@ -245,6 +288,14 @@ func nameProjection(list dnd.NPCRegistry) ([]byte, error) {
 	return json.Marshal(projection)
 }
 
+func identityProjection(list dnd.NPCRegistry) ([]byte, error) {
+	projection := identityProjectedNPCRegistry{NPCs: make([]identityProjectedNPC, len(list.NPCs))}
+	for index, npc := range list.NPCs {
+		projection.NPCs[index] = identityProjectedNPC{ID: npc.ID, Name: npc.Name}
+	}
+	return json.Marshal(projection)
+}
+
 func formatIdentityIssues(issues []identity.Issue) string {
 	parts := make([]string, len(issues))
 	for index, issue := range issues {

internal/modules/dnd/npcs/registry/registry_test.go

@@ -19,7 +19,7 @@ func TestResolveUnboundRegistryHasExactEmptyProjection(t *testing.T) {
 		t.Fatalf("Resolve() error = %v", err)
 	}
 	input := registry.PromptInput()
-	if registry.Bound() || registry.Digest() != "" || registry.Count() != 0 || string(input.Content) != emptyPrompt {
+	if registry.Bound() || registry.Digest() != "" || registry.Count() != 0 || string(input.Content) != emptyPrompt || string(registry.IdentityPromptInput().Content) != emptyPrompt {
 		t.Fatalf("registry = %#v input = %#v, want unbound empty registry", registry, input)
 	}
 	if registry.ProjectionDigest() == "" || input.Digest != registry.ProjectionDigest() || input.OriginURI != "" {
@@ -46,6 +46,21 @@ func TestResolveKeepsDurableProvenanceAndProjectsOnlyOrderedNames(t *testing.T)
 	}
 }
 
+func TestIdentityPromptInputProjectsOrderedIDsAndNames(t *testing.T) {
+	registry := resolveList(t, registryFixture())
+	input := registry.IdentityPromptInput()
+	want := `{"npcs":[{"id":"` + identity.DeriveID("Mira Thorn") + `","name":"Mira Thorn"},{"id":"` + identity.DeriveID("Captain Vale") + `","name":"Captain Vale"}]}`
+	if string(input.Content) != want || input.Digest == registry.ProjectionDigest() {
+		t.Fatalf("identity projection = %#v, want %s", input, want)
+	}
+	if npc, ok := registry.LookupID(identity.DeriveID("Mira Thorn")); !ok || npc.Name != "Mira Thorn" {
+		t.Fatalf("LookupID() = %#v, %t", npc, ok)
+	}
+	if _, ok := registry.LookupID("npc:unknown"); ok {
+		t.Fatal("LookupID() accepted an unknown ID")
+	}
+}
+
 func TestNameProjectionDigestTracksOnlyNamesAndOrder(t *testing.T) {
 	base := registryFixture()
 	evidenceChanged := registryFixture()