fix(agent): copy client_kwargs before mutating to prevent shared httpx.Client

run_agent.py

@@ -4364,7 +4364,9 @@ def _create_openai_client(self, client_kwargs: dict, *, reason: str, shared: boo
         # wrapped a closed transport and raised "Cannot send a request, as the client
         # has been closed" on every retry. The revert resolved that specific path; this
         # copy locks the contract so future transport/keepalive work can't reintroduce
-        # the same class of bug.
+        # the same class of bug. (#11249: the same in-place mutation also caused all
+        # per-request clients to share the primary's httpx.Client — closing any request
+        # client silently closed the primary too, breaking all subsequent calls.)
         client_kwargs = dict(client_kwargs)
         _validate_proxy_env_urls()
         _validate_base_url(client_kwargs.get("base_url"))

tests/run_agent/test_create_openai_client_kwargs_isolation.py

@@ -9,6 +9,16 @@
 (#10324, connections hanging in CLOSE-WAIT) is still open, so another transport
 tweak inside this function is likely. This test pins the contract that the
 function must treat its input dict as read-only.
+
+#11249 reported the same class of bug: without the shallow-copy guard,
+``_create_openai_client()`` wrote ``http_client`` back into the caller's dict,
+so every subsequent ``dict(self._client_kwargs)`` shallow-copy shared the
+*same* ``httpx.Client`` instance that was created for the primary client.
+Closing any request-scoped OpenAI client would therefore also close the
+primary's underlying transport, causing ``RuntimeError: Cannot send a request,
+as the client has been closed`` on all calls after the first.  The fix —
+``client_kwargs = dict(client_kwargs)`` at the top of the method — ensures
+each invocation operates on an independent local copy.
 """
 from unittest.mock import MagicMock, patch