[pcbeingused333]

When the ChatGPT sign-in path gets a non-streaming request, it forces a streamed Responses call and collapses the stream back into one message (openaiResponsesStreamToAnthropicResponse). That function only read response.completed and response.incomplete. A stream that ends with response.failed or error fell through to the text-only fallback, so the caller got an empty end_turn message with HTTP 200 and never saw the upstream error. The streaming translator already turns both events into an Anthropic error event.

The collapse now remembers the message of a response.failed or error event (same lookup as the streaming translator, with the same fallback text) and throws OpenAIResponsesStreamError when no final response arrived. A response.completed or response.incomplete that comes later still wins. buildOpenAICodexFetch catches that error and answers with { type: 'error', error: { type: 'api_error', message } } and status 502, the shape its other upstream failures use.

This is the same collapse helper as #143, on the ChatGPT sign-in path that #119 is reworking; the change stays inside that helper and its one caller, so it carries over or drops out with that rework.

Tests: proxy-streaming.test.ts checks that response.failed and error events (with and without a message) reject with the upstream message, and that a completed response after an earlier error is kept. fetch.test.ts checks the 502 body for a failed stream on a non-streaming call. On the previous code the fetch test gets HTTP 200 and the streaming test file does not compile its import. proxy-streaming, fetch and proxy-transform tests pass (75). This was only exercised with synthetic event streams, not against a live ChatGPT/Codex upstream. The CHANGELOG line is under Unreleased.

This change was made with Claude Code.

🤖 Generated with Claude Code

[GoDiao]

Thanks again! The fix is right. fetch.ts is the only caller, so the new throw stays contained, the 502 api_error body matches the other upstream failures there, and a later response.completed still wins. The tests cover each case.

A few small things before we merge:

1. Share the error lookup instead of copying it. upstreamErrorMessage is a copy of the lookup inside the response.failed / error case in openaiResponsesStreamToAnthropic.ts. If one copy changes later, the streaming and non-streaming paths will report different messages. Please extract it into an exported function there and call it from both places:

   // openaiResponsesStreamToAnthropic.ts
   export function upstreamErrorMessage(data: Record<string, unknown>): string {
     const response = data.response as Record<string, unknown> | undefined
     const error = (response?.error ?? data.error ?? data) as Record<string, unknown> | undefined
     return typeof error?.message === 'string' && error.message
       ? error.message
       : 'Upstream Responses stream failed'
   }

   Then const message = upstreamErrorMessage(data) in that case, and import it in openaiResponsesStreamToAnthropicResponse.ts. This touches one more file than you intended, but it's a small extraction and moves with the #119 rework just as easily.

2. No comments in new code. The project keeps new code free of comments, including JSDoc. This isn't written down in CONTRIBUTING yet, which is on us. Please drop the JSDoc on OpenAIResponsesStreamError and the "Same message lookup…" comment; the shared function makes the second one unnecessary anyway.

3. Rebase on main. CHANGELOG.md conflicts, because [Unreleased] on main already has a ### Fixed section. Moving your entry into it is enough.

Thanks for keeping these proxy fixes coming!

[pcbeingused333]

Thanks for the review, and sorry for the delay. All three points are addressed in the pushed commits:

1. upstreamErrorMessage is now one exported function in openaiResponsesStreamToAnthropic.ts, used by the response.failed / error case there and by openaiResponsesStreamToAnthropicResponse.ts; the copy is gone.
2. The JSDoc on OpenAIResponsesStreamError and the "Same message lookup…" comment are removed. Neither the new code nor the new tests carry comments.
3. Merged main into the branch (no force-push). The CHANGELOG.md entry now sits under the existing ### Fixed in [Unreleased].

proxy-streaming, fetch and proxy-transform tests still pass (75).

This update was prepared with Claude Code.

[GoDiao]

Thanks! All three points are in, and the tests cover each case.

[GoDiao]

Merged, thanks @pcbeingused333! Sharing the error lookup keeps the streaming and non-streaming paths reporting the same message, and the late-completion test pins the one case that's easy to get wrong. That's your third proxy fix here, and each one has come with tests that fail on the old code, which makes them easy to review.

Your CHANGELOG entry is in. If DreamCoder is useful to you, a ⭐ on the repo would mean a lot. Looking forward to the next one!