feat(auth): redirect messenger connect to success state

src/auth.js

@@ -179,7 +179,7 @@ export function verifyLoginChallengeCode({ challengeToken, code }) {
   };
 }
 
-export function createMessengerStartSession({ channel, email, userId }) {
+export function createMessengerStartSession({ channel, email, userId, redirectPath }) {
   purgeExpiredMessengerStartSessions();
 
   const startToken = crypto.randomBytes(24).toString('base64url');
@@ -188,6 +188,7 @@ export function createMessengerStartSession({ channel, email, userId }) {
     channel,
     email,
     userId,
+    redirectPath,
     expiresAt,
   });
 
@@ -210,6 +211,7 @@ export function consumeMessengerStartSession(startToken) {
     channel: payload.channel,
     email: payload.email,
     userId: payload.userId,
+    redirectPath: payload.redirectPath,
   };
 }
 

src/server.js

@@ -80,6 +80,14 @@ async function resolveUserForMessenger({ userId, email }) {
   });
 }
 
+function normalizeRedirectPath(value) {
+  const redirectPath = String(value || '').trim();
+  if (!redirectPath.startsWith('/')) {
+    return '';
+  }
+  return redirectPath;
+}
+
 async function resolveAuthenticatedUserFromRequest(req) {
   const authToken = extractAuthTokenFromRequest(req);
   const auth = verifyAccessToken(authToken);
@@ -103,6 +111,7 @@ app.post('/auth/messenger-start', async (req, res) => {
   const providedEmail = String(req.body?.email || '').trim().toLowerCase();
   const email = authenticatedUser?.email?.trim().toLowerCase() || providedEmail;
   const userId = authenticatedUser?.id ?? null;
+  const redirectPath = normalizeRedirectPath(req.body?.redirectPath);
 
   if (!userId && !/^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(email)) {
     res.status(400).json({ error: 'A valid email is required.' });
@@ -113,6 +122,7 @@ app.post('/auth/messenger-start', async (req, res) => {
     channel,
     email,
     userId,
+    redirectPath,
   });
 
   res.json({
@@ -179,7 +189,18 @@ app.post('/bot/messenger-login', async (req, res) => {
     process.env.NUXT_PUBLIC_SITE_URL ||
     'http://localhost:3000'
   ).replace(/\/$/, '');
-  const loginUrl = `${frontendUrl}/login?login_token=${encodeURIComponent(login.loginToken)}`;
+  const nextPath = startSession.redirectPath || (
+    startSession.userId
+      ? `/profile/notifications?status=success&connected=${channel.toLowerCase()}`
+      : ''
+  );
+  const loginQuery = new URLSearchParams({
+    login_token: login.loginToken,
+  });
+  if (nextPath) {
+    loginQuery.set('next', nextPath);
+  }
+  const loginUrl = `${frontendUrl}/login?${loginQuery.toString()}`;
 
   if (!skipDispatch) {
     const dispatch = await sendMessengerMessage({