diff --git a/python/packages/a2a/agent_framework_a2a/_agent.py b/python/packages/a2a/agent_framework_a2a/_agent.py
index 3d5ac41e86b..1261305bfbc 100644
--- a/python/packages/a2a/agent_framework_a2a/_agent.py
+++ b/python/packages/a2a/agent_framework_a2a/_agent.py
@@ -263,6 +263,8 @@ def __init__(
 
         super().__init__(id=id, name=name, description=description, **kwargs)
         self._http_client: httpx.AsyncClient | None = http_client
+        # every construction path must set this before __aexit__ can run
+        self._close_http_client = False
         self._timeout_config = self._create_timeout_config(timeout)
         bindings = supported_protocol_bindings if supported_protocol_bindings is not None else ["JSONRPC"]
         if client is not None:
diff --git a/python/packages/a2a/tests/test_a2a_agent.py b/python/packages/a2a/tests/test_a2a_agent.py
index 8ff147f98aa..9c111a2b11e 100644
--- a/python/packages/a2a/tests/test_a2a_agent.py
+++ b/python/packages/a2a/tests/test_a2a_agent.py
@@ -2536,3 +2536,37 @@ async def test_input_required_sets_task_id_instead_of_reference(mock_a2a_client:
 
 
 # endregion
+
+
+async def test_context_manager_with_user_supplied_http_client() -> None:
+    """A2AAgent(url=..., http_client=mine) must exit cleanly and must not close it.
+
+    The third construction path (no client, caller-provided http_client) used to
+    leave _close_http_client unset, so __aexit__ raised AttributeError.
+    """
+    mock_http_client = MagicMock()
+    mock_http_client.aclose = AsyncMock()
+
+    agent = A2AAgent(url="http://agent.example", http_client=mock_http_client)
+
+    async with agent:
+        pass
+
+    # the client belongs to the caller; we must not close it
+    mock_http_client.aclose.assert_not_called()
+
+
+async def test_context_manager_closes_self_created_http_client() -> None:
+    """A2AAgent(url=...) builds its own client and closes it on exit."""
+
+    with patch("agent_framework_a2a._agent.httpx.AsyncClient") as cls:
+        mock_http_client = MagicMock()
+        mock_http_client.aclose = AsyncMock()
+        cls.return_value = mock_http_client
+
+        agent = A2AAgent(url="http://agent.example")
+
+        async with agent:
+            pass
+
+        mock_http_client.aclose.assert_called_once()