[gleber]

Summary

Non-streaming chat completion responses can be served by upstream providers (notably Gemini) with a Content-Encoding: gzip body whose Content-Length describes the compressed byte count. readNonStreamingResponseBody reads upstream via response.text(), which transparently decompresses gzip — so by the time OmniRoute forwards, both the original Content-Encoding and Content-Length describe a payload that no longer exists.

Clients that honor Content-Length over a fully-buffered body then read only the first N bytes of the decompressed JSON and surface Unterminated string in JSON at position … parse failures.

Change

• Extract stripStaleForwardingHeaders(Headers): void in open-sse/handlers/chatCore.ts.
• Call it immediately after copying upstream headers on the non-stream forwarding path so the response framework can compute a fresh Content-Length (or fall through to Transfer-Encoding: chunked).
• Streaming paths are unaffected.

Test plan

• node --import tsx/esm --test tests/unit/chatcore-strip-stale-headers.test.ts — 3 passing
• Removes both headers; preserves unrelated headers (e.g. Content-Type, X-Request-Id)
• Case-insensitive (Content-Length vs content-length)
• No-op when the headers are absent

🤖 Generated with Claude Code

[gemini-code-assist]

Code Review

This pull request introduces the stripStaleForwardingHeaders utility to remove content-encoding and content-length headers from upstream responses before they are re-emitted. This ensures that downstream clients receive accurate metadata for decompressed or buffered payloads, preventing parsing errors. The changes include integration into the handleChatCore handler and the addition of a new unit test suite. Feedback suggests also stripping the Transfer-Encoding header as it is a hop-by-hop header that becomes invalid after buffering, along with corresponding updates to the unit tests.

[diegosouzapw]

Thanks @gleber! 🎉 Excellent bug fix — the RFC 7230 §6.1 compliance and the clear JSDoc documentation on why each header is stripped are top-notch. This resolves the gzipped Gemini response truncation issue cleanly without affecting streaming paths. Merging into release/v3.8.0.