fix(chat): migrate legacy cache to Elio conversation

src/data/storage/chat/local_chat_db.ts

@@ -9,12 +9,18 @@
  * 构造时 `dbName` 可注入，便于测试时每个用例用独立 DB 互不污染。
  */
 
-import Dexie, { type Table } from "dexie";
+import Dexie, { type Table, type Transaction } from "dexie";
+import { DEFAULT_CHARACTER_ID } from "@/data/constants/character";
 import type { ChatMediaKind } from "@/data/schemas/chat";
 import type {
   ChatImageData,
   ChatLockDetailData,
 } from "@/data/schemas/chat";
+import {
+  buildChatConversationKey,
+  buildChatMediaCacheKey,
+  isLegacyChatCacheOwnerKey,
+} from "@/lib/chat/chat_cache_keys";
 
 export interface LocalMessageRow {
   /** Dexie 自增主键（数据库内部使用，不暴露给 LocalMessage 类）。 */
@@ -71,5 +77,49 @@ export class LocalChatDB extends Dexie {
         // so retaining it would expose one identity's history to another.
         await transaction.table("messages").clear();
       });
+    this.version(4)
+      .stores({
+        messages: "++dbId, sessionId",
+        media: "cacheKey, ownerKey, messageId, kind, remoteUrl, updatedAt, lastAccessedAt",
+      })
+      .upgrade(migrateLegacyChatCacheToElio);
   }
 }
+
+async function migrateLegacyChatCacheToElio(
+  transaction: Transaction,
+): Promise<void> {
+  const messages = transaction.table<LocalMessageRow, number>("messages");
+  await messages.toCollection().modify((message) => {
+    const conversationKey = getElioConversationKey(message.sessionId);
+    if (conversationKey) message.sessionId = conversationKey;
+  });
+
+  const media = transaction.table<LocalChatMediaRow, string>("media");
+  const rows = await media.toArray();
+  for (const row of rows) {
+    const conversationKey = getElioConversationKey(row.ownerKey);
+    if (!conversationKey) continue;
+
+    const cacheKey = buildChatMediaCacheKey({
+      ownerKey: conversationKey,
+      messageId: row.messageId,
+      kind: row.kind,
+    });
+    const existing = await media.get(cacheKey);
+    await media.delete(row.cacheKey);
+    if (existing) continue;
+
+    await media.put({
+      ...row,
+      cacheKey,
+      ownerKey: conversationKey,
+    });
+  }
+}
+
+function getElioConversationKey(ownerKey: string): string | null {
+  return isLegacyChatCacheOwnerKey(ownerKey)
+    ? buildChatConversationKey(ownerKey, DEFAULT_CHARACTER_ID)
+    : null;
+}