# Notifications Troubleshooting (Go Backend)

> **Note**: This document has been updated for the 100% Go backend migration. Legacy Supabase edge function references are no longer applicable.

## Current Architecture

All notification APIs now use the Go backend with JWT authentication:
- **Register Token**: `POST /api/v1/notifications/device`
- **Unregister Token**: `DELETE /api/v1/notifications/device`
- **Get Notifications**: `GET /api/v1/notifications`

Authentication uses `Authorization: Bearer <token>` header with Go-issued JWTs.

---

## Common Issues

### 1. Token Not Syncing to Backend

**Symptoms:**
- FCM token obtained successfully but not stored in database
- Debug logs show `[FCM] Token synced with Go Backend successfully` not appearing

**Solutions:**
1. Verify user is authenticated before calling `NotificationService.init()`
2. Check API endpoint responds (network tab / logs)
3. Ensure JWT token is valid and not expired

### 2. Push Notifications Not Received

**Symptoms:**
- Token exists in database
- No push received on device

**Diagnosis:**
```sql
-- Check if token exists for user
SELECT * FROM user_fcm_tokens WHERE user_id = 'your-uuid';
```

**Solutions:**
1. Verify `FIREBASE_CREDENTIALS_FILE` path is correct in backend `.env`
2. Check Firebase Console for delivery reports
3. For web, verify `FIREBASE_WEB_VAPID_KEY` matches Firebase Console
4. On Android 13+, check `POST_NOTIFICATIONS` permission granted

### 3. Android 13+ Permission Denied

**Symptoms:**
- `[FCM] Android notification permission not granted: denied`

**Solution:**
The app now properly requests `POST_NOTIFICATIONS` at runtime. If user denied:
1. Guide them to Settings > Apps > Sojorn > Notifications
2. Enable notifications manually

### 4. Web Push Not Working

**Symptoms:**
- Token is null on web platform
- `[FCM] Web push is missing FIREBASE_WEB_VAPID_KEY`

**Solutions:**
1. Verify VAPID key in `lib/config/firebase_web_config.dart`
2. Key must match Firebase Console > Cloud Messaging > Web Push certificates
3. Must be served over HTTPS (except localhost)

### 5. Duplicate Tokens in Database

The schema now has a unique constraint on `(user_id, token)`:
```sql
UNIQUE(user_id, token)
```

This prevents duplicates via upsert logic:
```sql
ON CONFLICT (user_id, token) DO UPDATE SET last_updated = ...
```

---

## Logout Cleanup

On logout, the Flutter client now:
1. Calls backend to delete token from `user_fcm_tokens`
2. Deletes token from Firebase locally via `deleteToken()`
3. Resets initialization state

This ensures the device no longer receives notifications for the logged-out user.

---

## Testing Checklist

- [ ] Token registration works on Android
- [ ] Token registration works on Web
- [ ] Token appears in `user_fcm_tokens` table with correct `device_type`
- [ ] New message triggers push to recipient
- [ ] Post save triggers push to author
- [ ] Comment triggers push to post author
- [ ] Follow triggers push to followed user
- [ ] Tapping notification navigates correctly
- [ ] Logout removes token from database
- [ ] Re-login registers new token

---

## Related Documentation

- [FCM Implementation Guide](./fcm-implementation.md) - Complete implementation details
- [Backend API Documentation](../api/) - All API endpoints