Claude Code: Add CRITICAL STARTUP ERROR logging and stdout capture

- Wrap uvicorn startup with try-except using requested error format
- Add stdout handler to logging config for immediate capture
- Fix uvicorn log_config parameter to use proper defaults

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

app.py

@@ -24,11 +24,15 @@ def get_app():
 
     print(">>> CAIN: Creating FastAPI app...", flush=True)
 
-    # Configure stderr logging for real-time debugging (stdout can be buffered)
+    # Configure logging to both stdout and stderr for immediate capture
     logging.basicConfig(
         level=logging.INFO,
         format='%(asctime)s - %(levelname)s - %(message)s',
-        handlers=[logging.StreamHandler(sys.stderr)]
+        handlers=[
+            logging.StreamHandler(sys.stdout),  # Force stdout immediate capture
+            logging.StreamHandler(sys.stderr)
+        ],
+        force=True  # Override any existing config
     )
     logger = logging.getLogger(__name__)
     logger.info(">>> CAIN: FastAPI initialization starting")
@@ -97,13 +101,12 @@ if __name__ == "__main__":
     try:
         port = int(os.environ.get('PORT', 7860))
         print(f">>> CAIN: Starting uvicorn on port {port}...", flush=True, file=sys.stderr)
-        uvicorn.run("app:app", host="0.0.0.0", port=port, log_config="uvicorn.config:LOGGING_CONFIG")
+        uvicorn.run("app:app", host="0.0.0.0", port=port, log_config=None)
     except Exception as e:
-        # Log full stack trace to stderr before exiting
-        print(f">>> CAIN: FATAL - Main process crashed!", flush=True, file=sys.stderr)
-        print(f">>> CAIN: Error: {type(e).__name__}: {e}", flush=True, file=sys.stderr)
-        print(f">>> CAIN: Full traceback:", flush=True, file=sys.stderr)
-        traceback.print_exc(file=sys.stderr)
+        # Log full stack trace before exiting - use requested format
+        print(f"CRITICAL STARTUP ERROR: {e}", flush=True)
+        print(f"CRITICAL STARTUP ERROR: {e}", flush=True, file=sys.stderr)
+        traceback.print_exc()
         sys.exit(1)
     except KeyboardInterrupt:
         print("\n>>> CAIN: Interrupted by user", flush=True, file=sys.stderr)