refactor: change TTD persistence to iDB (#10662)

refactor: change ttd persistence to iDB

excalidraw-app/data/TTDStorage.ts

@@ -0,0 +1,51 @@
+import { createStore, get, set } from "idb-keyval";
+
+import type { SavedChats } from "@excalidraw/excalidraw/components/TTDDialog/types";
+
+import { STORAGE_KEYS } from "../app_constants";
+
+/**
+ * IndexedDB adapter for TTD chat storage.
+ * Implements TTDPersistenceAdapter interface.
+ */
+export class TTDIndexedDBAdapter {
+  /** IndexedDB database name */
+  private static idb_name = STORAGE_KEYS.IDB_TTD_CHATS;
+  /** Store key for chat data */
+  private static key = "ttdChats";
+
+  private static store = createStore(
+    `${TTDIndexedDBAdapter.idb_name}-db`,
+    `${TTDIndexedDBAdapter.idb_name}-store`,
+  );
+
+  /**
+   * Load saved chats from IndexedDB.
+   * @returns Promise resolving to saved chats array (empty if none found)
+   */
+  static async loadChats(): Promise<SavedChats> {
+    try {
+      const data = await get<SavedChats>(
+        TTDIndexedDBAdapter.key,
+        TTDIndexedDBAdapter.store,
+      );
+      return data || [];
+    } catch (error) {
+      console.warn("Failed to load TTD chats from IndexedDB:", error);
+      return [];
+    }
+  }
+
+  /**
+   * Save chats to IndexedDB.
+   * @param chats - The chats array to persist
+   */
+  static async saveChats(chats: SavedChats): Promise<void> {
+    try {
+      await set(TTDIndexedDBAdapter.key, chats, TTDIndexedDBAdapter.store);
+    } catch (error) {
+      console.warn("Failed to save TTD chats to IndexedDB:", error);
+      throw error;
+    }
+  }
+}