---
title: Backend Authentication Implementation Complete
type: note
permalink: project-management/backend-authentication-implementation-complete
---

# Backend Authentication Implementation

## Changes Made

### 1. Fixed SupabaseAuth to Support Modern Supabase Keys ✅
**File**: `backend/src/kinemotion_backend/auth.py`

```python
# Before: Only checked SUPABASE_ANON_KEY
self.supabase_anon_key = os.getenv("SUPABASE_ANON_KEY", "")

# After: Prefers modern keys, falls back to legacy
self.supabase_anon_key = (
    os.getenv("SUPABASE_PUBLISHABLE_KEY")
    or os.getenv("SUPABASE_ANON_KEY")
    or ""
)
```

This fixes JWT token verification in the `/api/analysis/sessions` endpoint when using modern Supabase API key format (`sb_publishable_...`).

---

### 2. Added Authentication to /analyze Endpoint ✅
**File**: `backend/src/kinemotion_backend/routes/analysis.py`

- Requires JWT token in `Authorization: Bearer <token>` header
- Extracts user_id from token
- Passes user_id to storage service for proper R2 organization
- **Backdoor for testing**: Accept `x-test-password` header to bypass auth

**New helper function**:
```python
async def get_user_id_for_analysis(
    credentials: HTTPAuthorizationCredentials | None = Depends(security),
    x_test_password: str | None = Header(None),
) -> str:
    # If TEST_PASSWORD matches x-test-password header, use test user ID
    # Otherwise validate JWT token
    # Returns user_id in both cases
```

---

### 3. Added Test Password Backdoor Utility ✅
**File**: `backend/src/kinemotion_backend/services/validation.py`

```python
def is_test_password_valid(x_test_password: str | None = None) -> bool:
    """Check if test password is valid (for debugging backdoor)."""
    test_password = os.getenv("TEST_PASSWORD")
    return bool(test_password and x_test_password == test_password)
```

This centralizes the backdoor check for reuse across endpoints.

---

## How the Authentication Flow Works

### For Production (Authenticated Users)
1. Frontend user logs in with Supabase auth
2. Frontend gets JWT token from `session.access_token`
3. Frontend includes `Authorization: Bearer <token>` header in POST to `/analyze`
4. Backend validates token using SupabaseAuth
5. Backend extracts user_id from token
6. Uploads organized in R2 as `uploads/{user_id}/2025/12/15/...`

### For Testing/Debugging (Backdoor)
1. Set `TEST_PASSWORD` environment variable on backend
2. Use curl or Postman with `x-test-password` header matching TEST_PASSWORD
3. Backend bypasses JWT validation
4. Uploads organized in R2 as `uploads/test-user-00000000-0000-0000-0000-000000000000/...` (or custom TEST_USER_ID)

**Example curl**:
```bash
curl -X POST http://localhost:8000/api/analyze \
  -H "x-test-password: my-secret-password" \
  -F "file=@video.mp4" \
  -F "jump_type=cmj" \
  -F "quality=balanced"
```

---

## Files Modified

1. ✅ `backend/src/kinemotion_backend/auth.py` - Support modern Supabase keys
2. ✅ `backend/src/kinemotion_backend/routes/analysis.py` - Add auth + backdoor
3. ✅ `backend/src/kinemotion_backend/services/validation.py` - Add backdoor check utility
4. ✅ `backend/src/kinemotion_backend/services/__init__.py` - Export backdoor utility

---

## Next Steps

1. **Deploy to Cloud Run** with these environment variables:
   - `SUPABASE_PUBLISHABLE_KEY` (already set)
   - `SUPABASE_SECRET_KEY` (already set)
   - `TEST_PASSWORD=your-secret-password` (for backdoor)
   - `TEST_USER_ID=optional-custom-test-user-id` (defaults to test-user-...)

2. **Update frontend** to send JWT token:
   ```typescript
   const token = session?.access_token
   const response = await fetch(`${backendUrl}/api/analyze`, {
     method: 'POST',
     headers: {
       'Authorization': `Bearer ${token}`
     },
     body: formData
   })
   ```

3. **Test feedback submission** end-to-end:
   - Upload video (authenticated)
   - See upload organized by user_id in R2
   - Save feedback (uses same auth)
   - Verify both operations use authenticated user

---

## Architecture Decision

✅ **Option A Selected**: Require authentication on both `/analyze` and `/api/analysis/sessions`

- All user uploads immediately organized by user_id in R2
- Single consistent auth model across all endpoints
- Rate limiting per-user (not per-IP)
- Full audit trail
- Backdoor for testing/debugging without creating test accounts
