Claude Code: Add full traceback logging middleware

- Import traceback and BaseMiddleware
- Replace function middleware with class-based LoggingMiddleware
- Log full stack trace with traceback.format_exc() on errors
- Return JSONResponse with 500 status instead of re-raising

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app.py

@@ -1,6 +1,8 @@
 import os
 import logging
+import traceback
 from fastapi import FastAPI, Request
+from starlette.middleware.base import BaseMiddleware
 from datetime import datetime
 from fastapi.responses import JSONResponse
 from pydantic import BaseModel
@@ -28,21 +30,29 @@ STARTUP_MODE = os.environ.get("STARTUP_MODE", "minimal")
 app = FastAPI()
 
 
-@app.middleware("http")
-async def log_requests(request: Request, call_next):
-    """Log all incoming requests and responses."""
-    start_time = datetime.utcnow()
-    logger.info(f"Request: {request.method} {request.url.path}")
-
-    try:
-        response = await call_next(request)
-        duration = (datetime.utcnow() - start_time).total_seconds()
-        logger.info(f"Response: {response.status_code} - {duration:.3f}s")
-        return response
-    except Exception as e:
-        duration = (datetime.utcnow() - start_time).total_seconds()
-        logger.error(f"Request failed after {duration:.3f}s: {str(e)}")
-        raise
+class LoggingMiddleware(BaseMiddleware):
+    """Middleware to log all requests and capture full tracebacks on errors."""
+
+    async def dispatch(self, request: Request, call_next):
+        """Process request with full error logging."""
+        start_time = datetime.utcnow()
+        logger.info(f"Request: {request.method} {request.url.path}")
+
+        try:
+            response = await call_next(request)
+            duration = (datetime.utcnow() - start_time).total_seconds()
+            logger.info(f"Response: {response.status_code} - {duration:.3f}s")
+            return response
+        except Exception as e:
+            duration = (datetime.utcnow() - start_time).total_seconds()
+            full_traceback = traceback.format_exc()
+            logger.error(f"Request failed after {duration:.3f}s:\n{full_traceback}")
+            return JSONResponse(
+                status_code=500,
+                content={"error": "Internal server error", "detail": str(e)}
+            )
+
+app.add_middleware(LoggingMiddleware)
 
 
 @app.exception_handler(Exception)