Minimize D&D NPC extraction contracts

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

@@ -5,6 +5,7 @@ package registry
 import (
 	"crypto/sha256"
 	"encoding/hex"
+	"encoding/json"
 	"fmt"
 	"mime"
 	"strings"
@@ -27,12 +28,13 @@ const (
 // Registry is an immutable, validated NPC registry prepared for prompt
 // grounding. All accessors return defensive copies.
 type Registry struct {
-	bound       bool
-	list        dnd.NPCList
-	canonical   []byte
-	digest      string
-	promptInput contracts.LLMInputMaterial
-	lookupByKey map[string]int
+	bound            bool
+	list             dnd.NPCList
+	canonical        []byte
+	digest           string
+	projectionDigest string
+	promptInput      contracts.LLMInputMaterial
+	lookupByKey      map[string]int
 }
 
 // Resolver retains only the validated construction-time registry and immutable
@@ -141,11 +143,13 @@ func Resolve(references contracts.ReferenceSet) (*Registry, error) {
 	slot, ok := references.Slots[ReferenceSlot]
 	if !ok {
 		content := []byte(emptyPrompt)
+		projectionDigest := semanticDigest(content)
 		return &Registry{
-			list:        dnd.NPCList{NPCs: []dnd.NPC{}},
-			canonical:   append([]byte(nil), content...),
-			promptInput: contracts.NewLLMInputMaterial(ReferenceSlot, npccodec.MediaType, content, "", ""),
-			lookupByKey: map[string]int{},
+			list:             dnd.NPCList{NPCs: []dnd.NPC{}},
+			canonical:        append([]byte(nil), content...),
+			projectionDigest: projectionDigest,
+			promptInput:      contracts.NewLLMInputMaterial(ReferenceSlot, npccodec.MediaType, content, projectionDigest, ""),
+			lookupByKey:      map[string]int{},
 		}, nil
 	}
 	if len(slot.Items) != 1 {
@@ -178,21 +182,24 @@ func Resolve(references contracts.ReferenceSet) (*Registry, error) {
 	}
 
 	list := cloneNPCList(value)
-	lookupByKey := make(map[string]int, len(list.NPCs)*2)
+	lookupByKey := make(map[string]int, len(list.NPCs))
 	for index, npc := range list.NPCs {
 		lookupByKey[identity.ComparisonKey(npc.Name)] = index
-		for _, alias := range npc.Aliases {
-			lookupByKey[identity.ComparisonKey(alias)] = index
-		}
 	}
 	digest := semanticDigest(content)
+	projection, err := nameProjection(list)
+	if err != nil {
+		return nil, fmt.Errorf("encode NPC name projection: %w", err)
+	}
+	projectionDigest := semanticDigest(projection)
 	return &Registry{
-		bound:       true,
-		list:        list,
-		canonical:   append([]byte(nil), content...),
-		digest:      digest,
-		promptInput: contracts.NewLLMInputMaterial(ReferenceSlot, npccodec.MediaType, content, digest, ""),
-		lookupByKey: lookupByKey,
+		bound:            true,
+		list:             list,
+		canonical:        append([]byte(nil), content...),
+		digest:           digest,
+		projectionDigest: projectionDigest,
+		promptInput:      contracts.NewLLMInputMaterial(ReferenceSlot, npccodec.MediaType, projection, projectionDigest, ""),
+		lookupByKey:      lookupByKey,
 	}, nil
 }
 
@@ -235,6 +242,15 @@ func (r *Registry) Digest() string {
 	return r.digest
 }
 
+// ProjectionDigest returns the SHA-256 digest of the exact names-only prompt
+// projection, including for an unbound or empty registry.
+func (r *Registry) ProjectionDigest() string {
+	if r == nil {
+		return ""
+	}
+	return r.projectionDigest
+}
+
 // Count returns the number of validated NPC records.
 func (r *Registry) Count() int {
 	if r == nil {
@@ -243,8 +259,8 @@ func (r *Registry) Count() int {
 	return len(r.list.NPCs)
 }
 
-// PromptInput returns the canonical registry as a content-safe prompt input.
-// Reference provenance is deliberately omitted.
+// PromptInput returns the names-only registry projection as a content-safe
+// prompt input. Durable IDs, evidence, and reference provenance are omitted.
 func (r *Registry) PromptInput() contracts.LLMInputMaterial {
 	if r == nil {
 		return contracts.LLMInputMaterial{}
@@ -252,8 +268,8 @@ func (r *Registry) PromptInput() contracts.LLMInputMaterial {
 	return r.promptInput.Clone()
 }
 
-// Lookup returns the canonical NPC for an exact canonical-name or alias match
-// under the NPC identity comparison policy.
+// 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) {
 	if r == nil {
 		return dnd.NPC{}, false
@@ -270,13 +286,26 @@ func semanticDigest(content []byte) string {
 	return "sha256:" + hex.EncodeToString(sum[:])
 }
 
+type projectedNPC struct {
+	Name string `json:"name"`
+}
+
+type projectedNPCList struct {
+	NPCs []projectedNPC `json:"npcs"`
+}
+
+func nameProjection(list dnd.NPCList) ([]byte, error) {
+	projection := projectedNPCList{NPCs: make([]projectedNPC, len(list.NPCs))}
+	for index, npc := range list.NPCs {
+		projection.NPCs[index] = projectedNPC{Name: npc.Name}
+	}
+	return json.Marshal(projection)
+}
+
 func formatIdentityIssues(issues []identity.Issue) string {
 	parts := make([]string, len(issues))
 	for index, issue := range issues {
 		location := fmt.Sprintf("record %d", issue.RecordIndex)
-		if issue.AliasIndex >= 0 {
-			location += fmt.Sprintf(" alias %d", issue.AliasIndex)
-		}
 		parts[index] = fmt.Sprintf("%s at %s", issue.Code, location)
 	}
 	return diagnostics.Aggregate("validate NPC registry identity", parts)
@@ -298,8 +327,6 @@ func cloneNPCs(values []dnd.NPC) []dnd.NPC {
 }
 
 func cloneNPC(value dnd.NPC) dnd.NPC {
-	value.Aliases = append([]string(nil), value.Aliases...)
-	value.Relationships = append([]dnd.NPCRelationship(nil), value.Relationships...)
 	value.SourceRefs = append([]source.SourceRef(nil), value.SourceRefs...)
 	return value
 }