Add global exception handler — no more bare 500s

backend/api/main.py

@@ -14,6 +14,7 @@ from pathlib import Path
 
 from fastapi import FastAPI, Request, Response
 from fastapi.middleware.cors import CORSMiddleware
+from fastapi.responses import JSONResponse
 from slowapi import Limiter, _rate_limit_exceeded_handler
 from slowapi.errors import RateLimitExceeded
 from slowapi.util import get_remote_address
@@ -110,6 +111,16 @@ app.state.limiter = limiter
 app.add_exception_handler(RateLimitExceeded, _rate_limit_exceeded_handler)
 
 
+@app.exception_handler(Exception)
+async def global_exception_handler(request: Request, exc: Exception):
+    """Catch-all: log unhandled exceptions and return structured JSON instead of bare 500."""
+    log.error("Unhandled exception on %s %s: %s", request.method, request.url.path, exc, exc_info=True)
+    return JSONResponse(
+        status_code=500,
+        content={"detail": f"Internal server error: {type(exc).__name__}: {exc}"},
+    )
+
+
 # -- Request logging --------------------------------------------------------
 
 @app.middleware("http")