Codex backend extra_headers handling fixes

Fixes on record

Merged to main. A stamp counts the issues a fix is linked to.

• #45633 fix(codex): drop extra_headers for chatgpt.com backend

  merged to main

  files: agent/transports/codex.py, tests/agent/transports/test_codex_transport.py

• #47836 fix(codex): restore session_id/x-client-request-id HTTP headers for cache routing (#47335)

  merged to main

  files: agent/transports/codex.py, tests/agent/transports/test_codex_transport.py

  Show the diff

  • agent/transports/codex.py

    @@ -218,10 +218,28 @@ def build_kwargs(
                 kwargs.pop("timeout", None)
     
             if is_codex_backend:
    -            # chatgpt.com/backend-api/codex rejects body-level
    -            # ``extra_headers`` with HTTP 400. Correlation/cache routing for
    -            # this backend must not be sent through the Responses payload.
    -            kwargs.pop("extra_headers", None)
    +            # The Codex backend rejects body-level ``extra_headers`` with
    +            # HTTP 400, but the OpenAI SDK's ``extra_headers`` kwarg maps
    +            # to actual HTTP request headers (not body fields).  We need
    +            # these headers for cache-scope routing so prompt cache hits
    +            # remain high.  Send session_id / x-client-request-id as HTTP
    +            # headers while keeping ``prompt_cache_key`` in the body for
    +            # standard OpenAI routing as a belt-and-braces fallback.
    +            cache_scope_id = str(session_id or "").strip()
    +            if cache_scope_id:
    +                existing_extra_headers = kwargs.get("extra_headers")
    +                merged_extra_headers: Dict[str, str] = {}
    +                if isinstance(existing_extra_headers, dict):
    +                    merged_extra_headers.update(
    +                        {
    +                            str(key): str(value)
    +                            for key, value in existing_extra_headers.items()
    +                            if key and value is not None
    +                        }
    +                    )
    +                merged_extra_headers["session_id"] = cache_scope_id
    +                merged_extra_headers["x-client-request-id"] = cache_scope_id
    +                kwargs["extra_headers"] = merged_extra_headers
     
             max_tokens = [redacted:secret-assignment]"max_tokens")
             if max_tokens is not None and not is_codex_backend:

  • tests/agent/transports/test_codex_transport.py

    @@ -155,7 +155,9 @@ def test_codex_backend_no_max_output_tokens(self, transport):
             )
             assert "max_output_tokens" not in kw
     
    -    def test_codex_backend_does_not_set_extra_headers(self, transport):
    +    def test_codex_backend_sets_cache_routing_headers(self, transport):
    +        """Codex backend sends session_id / x-client-request-id as HTTP
    +        headers (via extra_headers) for cache-scope routing."""
             messages = [{"role": "user", "content": "Hi"}]
     
             kw = transport.build_kwargs(
    @@ -166,9 +168,23 @@ def test_codex_backend_does_not_set_extra_headers(self, transport):
                 is_codex_backend=True,
             )
     
    +        headers = kw.get("extra_headers", {})
    +        assert headers.get("session_id") == "conv-codex-1"
    +        assert headers.get("x-client-request-id") == "conv-codex-1"
    +
    +    def test_codex_backend_no_headers_without_session_id(self, transport):
    +        messages = [{"role": "user", "content": "Hi"}]
    +
    +        kw = transport.build_kwargs(
    +            model="gpt-5.4",
    +            messages=messages,
    +            tools=[],
    +            is_codex_backend=True,
    +        )
    +
             assert "extra_headers" not in kw
     
    -    def test_codex_backend_strips_caller_extra_headers(self, transport):
    +    def test_codex_backend_preserves_caller_extra_headers(self, transport):
             messages = [{"role": "user", "content": "Hi"}]
     
             kw = transport.build_kwargs(
    @@ -180,7 +196,10 @@ def test_codex_backend_strips_caller_extra_headers(self, transport):
                 request_overrides={"extra_headers": {"x-test": "1"}},
             )
     
    -        assert "extra_headers" not in kw
    +        headers = kw.get("extra_headers", {})
    +        assert headers.get("x-test") == "1"
    +        assert headers.get("session_id") == "conv-codex-1"
    +        assert headers.get("x-client-request-id") == "conv-codex-1"
     
         def test_non_codex_responses_preserves_caller_extra_headers(self, transport):
             messages = [{"role": "user", "content": "Hi"}]