When proxying Codex Responses requests through the Chat Completions
format (api_format=openai_chat), the request transform only forwarded
plain `function` tools and silently dropped `tool_search`, `namespace`
(MCP), and `custom` tools, so third-party APIs never saw the official
Codex plugins and could not call them.
Introduce CodexToolContext, built from the original Responses request,
which flattens all four tool kinds into Chat functions and keeps a
chat_name -> CodexToolSpec map. The response path (streaming and
non-streaming) looks names up in this map to restore the original
tool_search_call / custom_tool_call / namespaced function_call items
instead of reparsing the flattened name. Long namespaced names are
truncated with a sha256 suffix to fit the 64-char Chat tool-name limit.
Covered by new round-trip tests for all four tool kinds across both
streaming and non-streaming paths.
Auto-detect each Chat-routed Codex provider's reasoning interface from
its name, base URL, and model, then inject the matching thinking
parameter without manual configuration:
- Platform-first inference (OpenRouter, SiliconFlow) overrides model
rules, since the same model exposes different reasoning controls
depending on the hosting platform.
- Effort tiers are forwarded only to providers that support them
(DeepSeek, OpenRouter, and StepFun's step-3.5-flash-2603); on/off-only
providers (Kimi, GLM, Qwen, MiniMax, MiMo, SiliconFlow) drop the level
instead of sending a field the upstream rejects.
- OpenRouter uses the native reasoning:{effort} object, clamps max to
xhigh (its enum has no max), and forwards an explicit effort:"none" so
reasoning can be turned off.
- StepFun falls back to inference so per-model effort support is honored
(the static preset would have forced effort on step-3.5-flash too).
Includes the Codex provider-form reasoning controls, i18n strings
(zh/en/ja), and response-side reasoning extraction.
- Add Codex provider API format selection and model mapping for Chat-only upstreams.
- Convert Codex Responses requests to Chat Completions and rebuild Chat responses as Responses output.
- Preserve reasoning_content across non-streaming, streaming, tool calls, and previous_response_id follow-ups.
- Add a bounded Codex Chat history cache for restoring tool calls before tool outputs.
- Cover Chat bridge, compact routing, streaming, and history recovery with focused tests.
Jason