Fix Codex /responses/compact passthrough

[Tr0sT]

Summary

• omit the unsupported store field for Codex /responses/compact
  requests
• force /responses/compact through the non-streaming JSON path even
  when the client omits stream:false or sends an SSE Accept header
• add regression coverage for compact request transformation and
  compact JSON handling

Testing

• node --import tsx/esm --test tests/unit/executor-codex.test.ts
• node --import tsx/esm --test --test-name-pattern 'Codex / responses/compact' tests/integration/chat-pipeline.test.ts
• npm run typecheck:core
• npx eslint open-sse/handlers/chatCore.ts tests/integration/chat- pipeline.test.ts tests/unit/executor-codex.test.ts
• locally verified Codex compact through OmniRoute after applying the
  NixOS package backport

[gemini-code-assist]

Code Review

This pull request introduces support for the Codex /responses/compact endpoint by ensuring it is treated as a non-streaming JSON request and that the store field is removed from the request body, as required by the backend. Changes include a new path-checking utility, logic updates in the chat handler and Codex executor, and comprehensive integration and unit tests. Feedback suggests deduplicating the endpoint validation logic by sharing a helper from the Codex executor and narrowing the scope of the non-streaming override to specifically target Codex passthrough requests to prevent unintended side effects.

[gemini-code-assist]

This function duplicates the logic found in open-sse/executors/codex.ts (where it is named isCompactResponsesEndpoint). It is better to export the helper from the Codex executor and import it here to ensure consistency and reduce maintenance overhead. Additionally, the implementation in codex.ts uses a more robust regex-based approach.

[gemini-code-assist]

The forced non-streaming mode for the compact endpoint should be scoped to Codex requests. Without checking the provider or the passthrough status, this logic could unintentionally affect other providers if they happen to use a similar path. Using the nativeCodexPassthrough flag (calculated at line 1094) is a reliable way to ensure this only applies to the intended Codex requests.

Suggested change

	const stream = isResponsesCompactEndpoint(endpointPath)
	? false
	: resolveStreamFlag(body?.stream, acceptHeader);
	const stream = (nativeCodexPassthrough && isResponsesCompactEndpoint(endpointPath))
	? false
	: resolveStreamFlag(body?.stream, acceptHeader);

[Tr0sT]

Thanks for the review. I addressed both comments in 10d56dba:

• reused the existing isCompactResponsesEndpoint helper from the
  Codex executor instead of duplicating endpoint parsing in chatCore
• scoped the forced non-streaming compact handling to
  nativeCodexPassthrough && isCompactResponsesEndpoint(endpointPath)

Re-ran the targeted checks:

• node --import tsx/esm --test tests/unit/executor-codex.test.ts
• node --import tsx/esm --test --test-name-pattern 'Codex / responses/compact' tests/integration/chat-pipeline.test.ts
• npm run typecheck:core
• npx eslint open-sse/handlers/chatCore.ts open-sse/executors/ codex.ts tests/integration/chat-pipeline.test.ts tests/unit/executor- codex.test.ts

[diegosouzapw]

Thanks @Tr0sT for this great contribution! 🎉 We've reviewed and merged this into the release/v3.7.5 branch. It will be part of the next release. We appreciate your effort!