use lowdb for faster iteration; use strings for ids and camelCase for field names for consistency

database/lowdb.ts

@@ -0,0 +1,30 @@
+import { Low } from "lowdb";
+import { JSONFile } from "lowdb/node";
+
+export type Conversation = {
+  id: string;
+  title: string;
+  userId: string;
+};
+
+type DB = {
+  conversations: Array<Conversation>;
+  messages: Array<{
+    id: string;
+    conversationId: string;
+    content: string;
+    role: "user" | "assistant" | "system" | "data";
+    index: number;
+    createdAt: string;
+    runningSummary?: string;
+  }>;
+};
+
+export const db = new Low<DB>(new JSONFile("db.json"), {
+  conversations: [],
+  messages: [],
+});
+/** Initialize the database. Sets `db.data` to the default state if the file doesn't exist. */
+await db.read();
+/** Write the database to the file, in case it didn't exist before. */
+await db.write();