Fix: Ensure UTF-8 encoding for all file operations

nanobot/session/manager.py

@@ -121,7 +121,7 @@ class SessionManager:
             created_at = None
             last_consolidated = 0
 
-            with open(path) as f:
+            with open(path, encoding="utf-8") as f:
                 for line in f:
                     line = line.strip()
                     if not line:
@@ -151,7 +151,7 @@ class SessionManager:
         """Save a session to disk."""
         path = self._get_session_path(session.key)
 
-        with open(path, "w") as f:
+        with open(path, "w", encoding="utf-8") as f:
             metadata_line = {
                 "_type": "metadata",
                 "created_at": session.created_at.isoformat(),
@@ -159,9 +159,10 @@ class SessionManager:
                 "metadata": session.metadata,
                 "last_consolidated": session.last_consolidated
             }
-            f.write(json.dumps(metadata_line) + "\n")
+            f.write(json.dumps(metadata_line, ensure_ascii=False) + "\n")
             for msg in session.messages:
-                f.write(json.dumps(msg) + "\n")
+                f.write(json.dumps(msg, ensure_ascii=False) + "\n")
+
 
         self._cache[session.key] = session
     
@@ -181,7 +182,7 @@ class SessionManager:
         for path in self.sessions_dir.glob("*.jsonl"):
             try:
                 # Read just the metadata line
-                with open(path) as f:
+                with open(path, encoding="utf-8") as f:
                     first_line = f.readline().strip()
                     if first_line:
                         data = json.loads(first_line)