diff --git a/template/server/messaging.py b/template/server/messaging.py
index 0b151f8e..244338fc 100644
--- a/template/server/messaging.py
+++ b/template/server/messaging.py
@@ -294,6 +294,14 @@ async def execute(
         if self._ws is None:
             raise Exception("WebSocket not connected")
 
+        message_id = str(uuid.uuid4())
+
+        # Phase A: prepare and send to kernel (under lock)
+        # The lock serializes the prepare+send phase to protect shared state
+        # (_global_env_vars init, _cleanup_task lifecycle, WebSocket sends).
+        # It is released before streaming results so that a client disconnect
+        # during streaming does not orphan the lock and block subsequent
+        # executions.  See https://github.com/e2b-dev/code-interpreter/issues/213
         async with self._lock:
             # Wait for any pending cleanup task to complete
             if self._cleanup_task and not self._cleanup_task.done():
@@ -327,7 +335,6 @@ async def execute(
                 )
                 complete_code = f"{indented_env_code}\n{complete_code}"
 
-            message_id = str(uuid.uuid4())
             execution = Execution()
             self._executions[message_id] = execution
 
@@ -362,11 +369,15 @@ async def execute(
                 )
                 await execution.queue.put(UnexpectedEndOfExecution())
 
-            # Stream the results
+        # Phase B: stream results (no lock held)
+        # Results are routed by unique message_id in _process_message(),
+        # so no shared state is accessed during streaming.
+        try:
             async for item in self._wait_for_result(message_id):
                 yield item
-
-            del self._executions[message_id]
+        finally:
+            # Clean up execution entry even if generator is abandoned
+            self._executions.pop(message_id, None)
 
             # Clean up env vars in a separate request after the main code has run
             if env_vars: