...

history/user_sessions.json

@@ -0,0 +1 @@
+{}

storage.py

@@ -26,5 +26,11 @@ def load_history(user_id: str) -> str:
 def load_full_history() -> dict:
     if not os.path.exists(HISTORY_FILE):
         return {}
-    with open(HISTORY_FILE, "r") as f:
-        return json.load(f)
+    try:
+        with open(HISTORY_FILE, "r") as f:
+            content = f.read().strip()
+            if not content:
+                return {}
+            return json.loads(content)
+    except json.JSONDecodeError:
+        return {}