Force codex stream to use chat completions

tests/test_core_flow.py

@@ -288,6 +288,30 @@ class CoreFlowTests(unittest.TestCase):
             self.assertEqual(endpoint.reasoning_effort, "high")
             self.assertEqual(endpoint.api_key_env, "OPENAI_API_KEY")
 
+    def test_codex_stream_forces_chat_completions_wire_api(self) -> None:
+        with tempfile.TemporaryDirectory() as tmp:
+            tmp_path = Path(tmp)
+            codex_dir = tmp_path / ".codex"
+            codex_dir.mkdir(parents=True)
+            (codex_dir / "config.toml").write_text(
+                '\n'.join(
+                    [
+                        'model_provider = "ipads"',
+                        "",
+                        "[model_providers.ipads]",
+                        'base_url = "http://codex.example/v1"',
+                        'wire_api = "responses"',
+                    ]
+                ),
+                encoding="utf-8",
+            )
+            with mock.patch.dict(os.environ, {"HOME": str(tmp_path)}, clear=True):
+                endpoint = LLMEndpointSpec.from_dict(
+                    {"provider": "codex", "model": "gpt-5.4", "stream": True}
+                )
+            self.assertTrue(endpoint.stream)
+            self.assertEqual(endpoint.wire_api, "chat.completions")
+
     def test_endpoint_stream_flag(self) -> None:
         endpoint = LLMEndpointSpec.from_dict(
             {