feat(entity): Chunk #4 remaining items — consistency UI, context rail, palette search, expanded seed & DATA_MODEL

- Consistency tab in EntitiesView surfacing findInconsistencies() results
- ContextRail + MentionPopover wired into WritingView for entity context/hover
- CommandPalette indexes entities and chapters for cross-entity search
- link field type for entity references in character fields
- findDeadCharacterMentions consistency check + tests
- Expand seed with a location, note, and a natural Elias Vell mention so the
  dead-character-after-death case is actually exercised
- Author docs/DATA_MODEL.md documenting core schemas, types, storage contract
- Rename CharacterMention id attr -> entityId to match core backlinks/consistency

packages/core/src/consistency.ts

@@ -5,6 +5,7 @@
  * See CHUNK #4 step 2.4.
  */
 import type { Character, Entity, ProseMirrorDoc } from "./types.js";
+import { collectMentionsInDoc } from "./backlinks.js";
 
 export type RelationshipSymmetry = "symmetric" | "directed";
 
@@ -32,7 +33,16 @@ export interface RelationshipIssue {
   relationship: string;
 }
 
-export type ConsistencyIssue = MentionIssue | RelationshipIssue;
+export interface DeadCharacterIssue {
+  kind: "dead-character-mentioned";
+  chapterId: string;
+  chapterTitle: string;
+  entityId: string;
+  /** The mention text, if any. */
+  name?: string | undefined;
+}
+
+export type ConsistencyIssue = MentionIssue | RelationshipIssue | DeadCharacterIssue;
 
 /**
  * Find mention nodes that reference an entity id that no longer exists (e.g.
@@ -44,25 +54,50 @@ export function findOrphanedMentions(
 ): MentionIssue[] {
   const issues: MentionIssue[] = [];
   for (const ch of chapters) {
-    const visit = (content: unknown[], _path: number[]): void => {
-      for (const node of content as Record<string, unknown>[]) {
-        if (!node || typeof node !== "object") continue;
-        if (node.type === "CharacterMention") {
-          const attrs = node.attrs as { entityId?: string; name?: string } | undefined;
-          if (attrs?.entityId && !entityIds.has(attrs.entityId)) {
-            issues.push({
-              kind: "orphan-mention",
-              chapterId: ch.id,
-              chapterTitle: ch.title,
-              entityId: attrs.entityId,
-              name: attrs.name,
-            });
-          }
-        }
-        if (Array.isArray(node.content)) visit(node.content as unknown[], _path);
+    const mentioned = collectMentionsInDoc(ch.doc);
+    for (const entityId of mentioned) {
+      if (!entityIds.has(entityId)) {
+        issues.push({
+          kind: "orphan-mention",
+          chapterId: ch.id,
+          chapterTitle: ch.title,
+          entityId,
+        });
       }
-    };
-    visit(ch.doc.content ?? [], []);
+    }
+  }
+  return issues;
+}
+
+/**
+ * Find characters who are marked `dead` but are still mentioned (by entity id)
+ * in a chapter body. A dead character should not appear alive in the story.
+ *
+ * Bare-name mentions (no `entityId`) are ignored — a reference to a name that
+ * is not yet an entity is an orphan-mention concern, not a dead-character one.
+ */
+export function findDeadCharacterMentions(
+  chapters: Array<{ id: string; title: string; doc: ProseMirrorDoc }>,
+  entities: Entity[],
+): DeadCharacterIssue[] {
+  const dead = new Set(
+    entities
+      .filter((e): e is Character => !("fields" in e) && !("body" in e) && e.status === "dead")
+      .map((c) => c.id),
+  );
+  const issues: DeadCharacterIssue[] = [];
+  for (const chapter of chapters) {
+    const mentioned = collectMentionsInDoc(chapter.doc);
+    for (const entityId of mentioned) {
+      if (dead.has(entityId)) {
+        issues.push({
+          kind: "dead-character-mentioned",
+          chapterId: chapter.id,
+          chapterTitle: chapter.title,
+          entityId,
+        });
+      }
+    }
   }
   return issues;
 }
@@ -125,6 +160,7 @@ export function findInconsistencies(
   const issues: ConsistencyIssue[] = [
     ...findOrphanedMentions(chapters, entityIds),
     ...findRelationshipAsymmetry(entities),
+    ...findDeadCharacterMentions(chapters, entities),
   ];
   return issues;
 }