Refactor: improve thread safety and code organization

- Add dedicated _breaker_lock for thread-safe circuit breaker state access
- Extract _format_search_results() helper to eliminate DRY violation
- Document unused session_id parameters for API compatibility

__init__.py

@@ -151,6 +151,7 @@ class Mem0LocalMemoryProvider(MemoryProvider):
         self._prefetch_thread = None
         self._sync_thread = None
         # Circuit breaker state
+        self._breaker_lock = threading.Lock()
         self._consecutive_failures = 0
         self._breaker_open_until = 0.0
 
@@ -230,6 +231,7 @@ class Mem0LocalMemoryProvider(MemoryProvider):
 
     def _is_breaker_open(self) -> bool:
         """Return True if the circuit breaker is tripped (too many failures)."""
+        with self._breaker_lock:
             if self._consecutive_failures < _BREAKER_THRESHOLD:
                 return False
             if time.monotonic() >= self._breaker_open_until:
@@ -238,9 +240,11 @@ class Mem0LocalMemoryProvider(MemoryProvider):
             return True
 
     def _record_success(self):
+        with self._breaker_lock:
             self._consecutive_failures = 0
 
     def _record_failure(self):
+        with self._breaker_lock:
             self._consecutive_failures += 1
             if self._consecutive_failures >= _BREAKER_THRESHOLD:
                 self._breaker_open_until = time.monotonic() + _BREAKER_COOLDOWN_SECS
@@ -251,6 +255,15 @@ class Mem0LocalMemoryProvider(MemoryProvider):
                     _BREAKER_COOLDOWN_SECS,
                 )
 
+    def _format_search_results(self, results: List[Dict]) -> str:
+        """Format search results into a bullet list string."""
+        lines = [
+            r.get("text") or r.get("memory", "")
+            for r in results
+            if r.get("text") or r.get("memory")
+        ]
+        return "\n".join(f"- {line}" for line in lines) if lines else ""
+
     def initialize(self, session_id: str, **kwargs) -> None:
         self._config = _load_config()
         # Prefer gateway-provided user_id for per-user memory scoping
@@ -296,21 +309,22 @@ class Mem0LocalMemoryProvider(MemoryProvider):
                 limit=5,
             )
             if results:
-                lines = [
-                    r.get("text") or r.get("memory", "")
-                    for r in results
-                    if r.get("text") or r.get("memory")
-                ]
-                if lines:
+                formatted = self._format_search_results(results)
+                if formatted:
                     self._record_success()
-                    return "\n".join(f"- {line}" for line in lines)
+                    return formatted
         except Exception as e:
             self._record_failure()
             logger.debug("Mem0 prefetch failed: %s", e)
         return ""
 
     def queue_prefetch(self, query: str, *, session_id: str = "") -> None:
-        """Queue async prefetch for next turn (called before LLM request)."""
+        """Queue async prefetch for next turn (called before LLM request).
+
+        Args:
+            query: Search query for prefetching memories.
+            session_id: Unused. Kept for API compatibility.
+        """
         if self._is_breaker_open():
             return
 
@@ -323,13 +337,9 @@ class Mem0LocalMemoryProvider(MemoryProvider):
                     limit=5,
                 )
                 if results:
-                    lines = [
-                        r.get("text") or r.get("memory", "")
-                        for r in results
-                        if r.get("text") or r.get("memory")
-                    ]
+                    formatted = self._format_search_results(results)
                     with self._prefetch_lock:
-                        self._prefetch_result = "\n".join(f"- {line}" for line in lines)
+                        self._prefetch_result = formatted
                 self._record_success()
             except Exception as e:
                 self._record_failure()
@@ -343,7 +353,13 @@ class Mem0LocalMemoryProvider(MemoryProvider):
     def sync_turn(
         self, user_content: str, assistant_content: str, *, session_id: str = ""
     ) -> None:
-        """Send the turn to Mem0 for server-side fact extraction (non-blocking)."""
+        """Send the turn to Mem0 for server-side fact extraction (non-blocking).
+
+        Args:
+            user_content: User message content.
+            assistant_content: Assistant response content.
+            session_id: Unused. Kept for API compatibility.
+        """
         if self._is_breaker_open():
             return