fix: add debug log file locking, improve error logging, validate cloud API key

- Add portalocker file locking to debug_log() to prevent interleaved entries
- Add exc_info=True to curator _call_llm error logging for stack traces
- Add debug log message on JSON parse fallback in _parse_json_response
- Warn when cloud is enabled but API key env var is not set

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

app/config.py

@@ -113,6 +113,13 @@ class Config:
                     models=cloud_data.get("models", {})
                 )
 
+        if config.cloud.enabled and not config.cloud.api_key:
+            import logging
+            logging.getLogger(__name__).warning(
+                "Cloud is enabled but API key env var '%s' is not set",
+                config.cloud.api_key_env
+            )
+
         return config
 
 config = Config.load()

app/curator.py

@@ -212,7 +212,7 @@ Remember: Respond with ONLY valid JSON. No markdown, no explanations, just the J
                 result = response.json()
                 return result.get("response", "")
         except Exception as e:
-            logger.error(f"Failed to call LLM: {e}")
+            logger.error(f"LLM call failed: {e}", exc_info=True)
             return ""
 
     def _parse_json_response(self, response: str) -> Optional[Dict]:
@@ -223,6 +223,7 @@ Remember: Respond with ONLY valid JSON. No markdown, no explanations, just the J
         try:
             return json.loads(response)
         except json.JSONDecodeError:
+            logger.debug("Direct JSON parse failed, trying brace extraction")
             pass
 
         try:

app/proxy_handler.py

@@ -6,6 +6,7 @@ import json
 import re
 import logging
 import os
+import portalocker
 from pathlib import Path
 from .config import config
 from .singleton import get_qdrant_service
@@ -66,7 +67,9 @@ def debug_log(category: str, message: str, data: dict = None):
         entry["data"] = data
     
     with open(log_path, "a") as f:
+        portalocker.lock(f, portalocker.LOCK_EX)
         f.write(json.dumps(entry) + "\n")
+        portalocker.unlock(f)
 
 
 async def handle_chat_non_streaming(body: dict):