myTradeTracker/ROOT_CAUSE_FOUND.md

ROOT CAUSE FOUND! 🎯

The Diagnostic Revealed Everything

Your diagnostic output showed the exact problem:

What We Saw

Registered Routes (from diagnostic):

POST       /api/accounts/
GET        /api/accounts/

Notice the trailing slash? (/api/accounts/)

HTTP Response (from diagnostic):

HTTP/1.1 307 Temporary Redirect
location: http://localhost:8000/api/accounts/

The backend was redirecting FROM /api/accounts TO /api/accounts/

Why This Was Happening

The Route Definition

In accounts.py, the routes were defined as:

@router.get("/", response_model=List[AccountResponse])
def list_accounts(...):
    ...

How FastAPI Combines Paths

When you register the router in main.py:

app.include_router(
    accounts.router,
    prefix="/api/accounts",  # <-- prefix
    tags=["accounts"]
)

FastAPI combines them:

prefix: "/api/accounts" + route: "/" = "/api/accounts/"
                                        ↑ trailing slash!

What the Frontend Was Doing

Your React frontend was calling:

fetch('http://starship2:8000/api/accounts')  // No trailing slash

The Result

1. Frontend: GET /api/accounts (no slash)
2. Backend: "I only have /api/accounts/ (with slash)"
3. Backend: "Let me redirect you there: HTTP 307"
4. Frontend: "I don't follow redirects automatically, request fails"
5. UI: Spinning loading indicator forever

The Fix

Changed all route decorators from:

@router.get("/", ...)    # Creates /api/accounts/

To:

@router.get("", ...)     # Creates /api/accounts

Now when combined:

prefix: "/api/accounts" + route: "" = "/api/accounts"
                                      ↑ NO trailing slash!

Perfect match with what the frontend calls!

Files Fixed

1. backend/app/api/endpoints/accounts.py

   • Changed @router.post("/") → @router.post("")
   • Changed @router.get("/") → @router.get("")

2. backend/app/api/endpoints/positions.py

   • Changed @router.get("/") → @router.get("")

3. backend/app/api/endpoints/transactions.py

   • Changed @router.get("/") → @router.get("")

Why Previous Fixes Didn't Work

We spent time trying to fix:

• Docker cache (not the issue)
• Database connection (not the issue)
• redirect_slashes parameter (not the issue)
• Environment variables (not the issue)

The real issue was simply the trailing slash in route paths!

How To Apply The Fix

Option 1: Quick Transfer (Recommended)

On your Mac:

cd /Users/chris/Desktop/fidelity
./transfer-final-fix.sh

Then on your server:

cd ~/fidelity
./FINAL_FIX.sh

Option 2: Manual Transfer

# On Mac
cd /Users/chris/Desktop/fidelity

scp backend/app/api/endpoints/accounts.py pi@starship2:~/fidelity/backend/app/api/endpoints/
scp backend/app/api/endpoints/positions.py pi@starship2:~/fidelity/backend/app/api/endpoints/
scp backend/app/api/endpoints/transactions.py pi@starship2:~/fidelity/backend/app/api/endpoints/
scp FINAL_FIX.sh pi@starship2:~/fidelity/

# On Server
ssh pi@starship2
cd ~/fidelity
chmod +x FINAL_FIX.sh
./FINAL_FIX.sh

What Will Happen

The FINAL_FIX.sh script will:

1. Stop containers
2. Remove backend image
3. Rebuild backend with fixed code
4. Start services
5. Test automatically
6. Show SUCCESS! if it works

Expected Result

After the fix:

• ✅ GET /api/accounts returns HTTP 200 (not 307!)
• ✅ Response: [] (empty array)
• ✅ Account creation works in UI
• ✅ No more spinning/loading forever

Why The Diagnostic Was So Helpful

The diagnostic showed:

1. ✅ Backend had correct main.py (no redirect_slashes=False)
2. ✅ Database connection worked perfectly
3. ✅ Environment variables were correct
4. ✅ Image was freshly built (2 minutes ago)
5. ❌ But routes were registered WITH trailing slashes
6. ❌ And HTTP test returned 307 redirect

This pointed directly to the route path issue!

Lesson Learned

FastAPI's route registration is simple but subtle:

# These are DIFFERENT:
@router.get("/")   # With trailing slash
@router.get("")    # Without trailing slash

# When combined with prefix "/api/accounts":
"/api/accounts" + "/"  = "/api/accounts/"   # Not what we want
"/api/accounts" + ""   = "/api/accounts"    # Perfect!

Final Note

This is a common FastAPI gotcha. The framework's redirect_slashes=True parameter is supposed to handle this, but when routes are registered with explicit trailing slashes, it creates the redirect behavior we saw.

By using empty string "" for the root route of each router, we match exactly what the frontend expects, and everything works!

---

Status: ✅ Root cause identified and fixed! Next: Transfer files and rebuild Expected: Account creation should work perfectly!