fix(agent): preserve Codex message items for replay

tests/agent/transports/test_chat_completions.py

@@ -33,15 +33,18 @@ class TestChatCompletionsBasic:
     def test_convert_messages_strips_codex_fields(self, transport):
         msgs = [
             {"role": "assistant", "content": "ok", "codex_reasoning_items": [{"id": "rs_1"}],
+             "codex_message_items": [{"id": "msg_1", "type": "message"}],
              "tool_calls": [{"id": "call_1", "call_id": "call_1", "response_item_id": "fc_1",
                             "type": "function", "function": {"name": "t", "arguments": "{}"}}]},
         ]
         result = transport.convert_messages(msgs)
         assert "codex_reasoning_items" not in result[0]
+        assert "codex_message_items" not in result[0]
         assert "call_id" not in result[0]["tool_calls"][0]
         assert "response_item_id" not in result[0]["tool_calls"][0]
         # Original list untouched (deepcopy-on-demand)
         assert "codex_reasoning_items" in msgs[0]
+        assert "codex_message_items" in msgs[0]
 
 
 class TestChatCompletionsBuildKwargs:

tests/agent/transports/test_codex_transport.py

@@ -194,6 +194,36 @@ class TestCodexNormalizeResponse:
         assert nr.content == "Hello world"
         assert nr.finish_reason == "stop"
 
+    def test_message_items_preserved_in_provider_data(self, transport):
+        """Codex assistant message item ids/phases must survive transport normalization."""
+        r = SimpleNamespace(
+            output=[
+                SimpleNamespace(
+                    type="message",
+                    role="assistant",
+                    id="msg_abc",
+                    phase="final_answer",
+                    content=[SimpleNamespace(type="output_text", text="Hello world")],
+                    status="completed",
+                ),
+            ],
+            status="completed",
+            incomplete_details=None,
+            usage=SimpleNamespace(input_tokens=10, output_tokens=5,
+                                  input_tokens_details=None, output_tokens_details=None),
+        )
+        nr = transport.normalize_response(r)
+        assert nr.codex_message_items == [
+            {
+                "type": "message",
+                "role": "assistant",
+                "status": "completed",
+                "content": [{"type": "output_text", "text": "Hello world"}],
+                "id": "msg_abc",
+                "phase": "final_answer",
+            }
+        ]
+
     def test_tool_call_response(self, transport):
         """Normalize a Codex response with tool calls."""
         r = SimpleNamespace(

tests/agent/transports/test_transport.py

@@ -60,6 +60,13 @@ class TestTransportRegistry:
         assert t is not None
         assert t.api_mode == "anthropic_messages"
 
+    def test_discovers_missing_transport_when_registry_partially_populated(self):
+        """Importing one transport directly must not hide other valid api_modes."""
+        import agent.transports.chat_completions  # noqa: F401
+        t = get_transport("codex_responses")
+        assert t is not None
+        assert t.api_mode == "codex_responses"
+
     def test_register_and_get(self):
         class DummyTransport(ProviderTransport):
             @property

tests/agent/transports/test_types.py

@@ -270,3 +270,15 @@ class TestNormalizedResponseBackwardCompat:
     def test_codex_reasoning_items_none_when_absent(self):
         nr = NormalizedResponse(content="hi", tool_calls=None, finish_reason="stop")
         assert nr.codex_reasoning_items is None
+
+    def test_codex_message_items_from_provider_data(self):
+        items = [{"id": "msg_1", "type": "message"}]
+        nr = NormalizedResponse(
+            content="hi", tool_calls=None, finish_reason="stop",
+            provider_data={"codex_message_items": items},
+        )
+        assert nr.codex_message_items == items
+
+    def test_codex_message_items_none_when_absent(self):
+        nr = NormalizedResponse(content="hi", tool_calls=None, finish_reason="stop")
+        assert nr.codex_message_items is None