Python: FastAPI Depends() not tracked, causes false dead code positives

[RyanKim17920]

Bug

Functions used via FastAPI's Depends() show in_degree=0 and appear as dead code, despite being called on every request.

Root Cause

async def endpoint(user: UserSchema = Depends(get_current_user)):
    ...

get_current_user is passed as a reference, not called directly. No CALLS or USAGE edge is created, so it looks uncalled.

Confirmed False Positives (FastAPI project)

• get_current_user — used via Depends() in every protected route
• get_current_user_optional — same, 4 routers
• All dependencies.py factory functions (get_paper_action_service, get_user_service, etc.)

Suggested Fix

Detect Depends(func_ref) in parameter default values via tree-sitter and emit a USAGE edge from the handler to func_ref.

Impact

High — marks live auth functions as dead code, risking incorrect deletion.