feat(bot): add Baileys session wrapper

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/bot/src/whatsapp/session.ts

@@ -0,0 +1,74 @@
+import { mkdir } from "node:fs/promises";
+import { join } from "node:path";
+import {
+  makeWASocket,
+  useMultiFileAuthState,
+  type WASocket,
+  type ConnectionState,
+  DisconnectReason,
+  Browsers,
+} from "@whiskeysockets/baileys";
+import { logger } from "../logger.js";
+import { env } from "../env.js";
+
+export type SessionEvent =
+  | { type: "qr"; payload: string }
+  | { type: "open"; phoneNumber: string | undefined }
+  | { type: "close"; reason: number; loggedOut: boolean };
+
+export type SessionEventHandler = (event: SessionEvent) => void | Promise<void>;
+
+export type Session = {
+  accountId: string;
+  socket: WASocket;
+  close: () => Promise<void>;
+};
+
+export async function startSession(params: {
+  accountId: string;
+  onEvent: SessionEventHandler;
+}): Promise<Session> {
+  const { accountId, onEvent } = params;
+  const sessionDir = join(env.SESSIONS_DIR, accountId);
+  await mkdir(sessionDir, { recursive: true });
+
+  const { state, saveCreds } = await useMultiFileAuthState(sessionDir);
+
+  const socket = makeWASocket({
+    auth: state,
+    printQRInTerminal: false,
+    browser: Browsers.macOS("Safari"),
+    syncFullHistory: false,
+    logger: logger.child({ accountId, component: "baileys" }) as never,
+  });
+
+  socket.ev.on("creds.update", () => void saveCreds());
+
+  socket.ev.on("connection.update", (update: Partial<ConnectionState>) => {
+    if (update.qr) {
+      void onEvent({ type: "qr", payload: update.qr });
+    }
+    if (update.connection === "open") {
+      const phoneNumber = socket.user?.id?.split(":")[0];
+      void onEvent({ type: "open", phoneNumber });
+    }
+    if (update.connection === "close") {
+      const reason =
+        (update.lastDisconnect?.error as { output?: { statusCode?: number } } | undefined)?.output?.statusCode ?? 0;
+      const loggedOut = reason === DisconnectReason.loggedOut;
+      void onEvent({ type: "close", reason, loggedOut });
+    }
+  });
+
+  return {
+    accountId,
+    socket,
+    close: async () => {
+      try {
+        socket.end(undefined);
+      } catch (err) {
+        logger.warn({ err, accountId }, "session.close: error closing socket");
+      }
+    },
+  };
+}