fix(responses): stabilize large native HTTP uploads (carry #6508)

[lidge-jun]

Summary

• Carry fix(responses): encode large native Codex HTTP uploads as bytes #6508 (dd4fc9a8f732699d88f46058c3298073d9aa2317) with its original author and source reference. Large native ChatGPT Responses/compact HTTP strings become identical UTF-8 bytes only at the final physical-send boundary, avoiding the large-string upload reset described in the source PR.
• Keep final destination selection, egress, headers, cancellation, manual redirects, WebSocket selection and replay refusal unchanged. Add exact threshold, destination-away and abort propagation regressions alongside the source tests and update transport/user documentation.
• This is the transport slice of release Lane A. Issue [Provider compatibility] Claude Code /compact gets stuck on 502 retries with native GPT-6.1 Sol #6504's Messages error projection is a separate follow-up; this PR does not claim to fix client compaction or expand upstream context limits. Leave the source PR open for coordinator disposition.

Co-authored-by: Maxy Milan Sorée maxy@mxymedia.nl

Verification

• bun test tests/responses/responses-fetch-helpers-boundary.test.ts tests/responses/fresh-connection-optout.test.ts tests/responses/provider-egress-fetch.test.ts tests/server/fetch-header-timeout.test.ts tests/server/upstream-http-version.test.ts tests/lib/plugin-upstream-hooks.test.ts tests/responses/ws-upstream.test.ts — 199 passed, 0 failed; one older-runtime WebSocket case skipped on Bun 1.4.0 (not claimed as passing).
• Mutation check: removing the conversion produced six boundary-regression failures; restoring it passed the affected tests.
• bun run typecheck, bun run privacy:scan, bun run structure:check — passed. cd docs-site && bun install --frozen-lockfile && bun run build — passed (561 pages, 77,932 internal links).
• The full local suite was not run because concurrent release worktrees share resources. Focused transport coverage is above; applicable exact-head PR CI remains required before integration.
• Source author reported a real macOS native synthetic upload success. This lane independently verifies byte/destination/metadata/replay behavior with synthetic executors; it has not repeated a live ChatGPT upload, captured private conversation content, or exercised packaged Windows behavior.
• Independent implementation/security review: PASS, no blocking findings; included four additional synthetic boundary probes. Coordinator owns merge and final integrated CI.

Checklist

• Scope stays focused and avoids unrelated cleanup.
• Docs or release notes were updated when needed.
• Security-sensitive changes were reviewed for secrets, auth, and unsafe defaults.

Summary by CodeRabbit

• Bug Fixes
  • Large native ChatGPT Responses and compact HTTPS requests now use UTF-8 byte-buffer uploads when their string bodies are at least 1 MiB. Request contents and metadata are preserved, and automatic retries are not added. Smaller requests, other destinations, and existing byte or stream bodies are unchanged.
• Documentation
  • Updated server and transport documentation to describe large-request upload behavior and its scope.

[chatgpt-codex-connector]

Codex Review Summary

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-03T14:26:23.225900Z	82507bd	PR opened

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ℹ️ Recent review info

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• Run ID: 1248dd53-d25e-4838-b544-e3106aad4176

📥 Commits

Reviewing files that changed from the base of the PR and between 82507bd and db094c4.

📒 Files selected for processing (1)

• docs-site/src/content/docs/reference/configuration/server.md

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📝 Walkthrough

Walkthrough

The PR converts qualifying native Responses and compact HTTP request bodies to UTF-8 buffers before sending. It adds boundary tests and transport documentation. Release-lane records describe validation and publication, and include a separate Messages error-handling plan that is not implemented here.

Changes

Native upload and release lane

Layer / File(s)	Summary
Upload boundary and regression coverage src/server/responses/fetch-helpers.ts, tests/responses/responses-fetch-helpers-boundary.test.ts, devlog/_plan/261003_release_lane_a/010_native_upload.md	At the final send, string bodies of at least 1 MiB in UTF-8 are converted to buffers only for the exact native Responses or compact HTTPS endpoints. Tests cover threshold boundaries, destination selection, dispatch, request metadata, and failure propagation without retries.
Transport behavior documentation docs-site/src/content/docs/reference/configuration/server.md, structure/transports/byte-accounting.md, structure/transports/responses.md, devlog/_plan/261003_release_lane_a/010_native_upload.md	Documentation describes the conversion scope and preserved request properties. It states that automatic retries remain disabled and that existing body limits and serialization-observation lifetime are unchanged.
Release scope and validation records devlog/_plan/261003_release_lane_a/000_plan.md, devlog/_plan/261003_release_lane_a/001_evidence.md, devlog/_plan/261003_release_lane_a/020_messages_context.md, devlog/_plan/261003_release_lane_a/030_review_publication.md	The lane files record scope, evidence, validation and publication conditions. The Messages context-error handling is specified as a plan; this PR does not implement it.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix

Merge Risk: ⚪ Minimal · up to db094

Qualifying native uploads use UTF-8 bytes while other request forms and destinations retain their behavior. No concrete issue requiring a fix before merge was established; normal exact-head checks still apply.

Architecture Summary

Architecture risk: 🔵 Low · up to db094

The change affects 5 systems.

Changed systems: devlog, structure, docs-site, src, tests

Architecture concerns
No architecture-level concerns identified.

Review details

Systems and components

• observed — devlog (service) was modified; 5 changed files map to changed impact.
• observed — structure (service) was modified; 2 changed files map to changed impact.
• observed — docs-site (service) was modified; 1 changed file maps to changed impact.
• observed — src (service) was modified; 1 changed file maps to changed impact.

Before / after behavior

• observed — Modified behavior in devlog/_plan/261003_release_lane_a/000_plan.md: Adds the Lane A scope, decisions, file map, verification and stop conditions, documentation updates, and roadmap conclusion. The plan requires single-send transport invariants and preservation of recognized context errors through both encoders and non-stream failure handling; unknown failures keep prior 502/529 behavior. It excludes retries, payload pruning, account changes, merging, and release, and requires applicable exact-head CI before completion.
• observed — Modified behavior in devlog/_plan/261003_release_lane_a/001_evidence.md: Added source and issue inspection notes, implementation ownership references, and transport baseline results. The notes record missing runtime proof, limitations in the available wire evidence, and that private-conversation capture and paid upstream probes were not run.
• observed — Modified behavior in devlog/_plan/261003_release_lane_a/001_evidence.md: Added Messages test baseline results, architecture and reviewer decisions, and a synthetic local probe result. The probe is documented as evidence of error surfacing and prompt termination only, not proof of zero retries or automatic compaction.
• observed — Modified behavior in devlog/_plan/261003_release_lane_a/001_evidence.md: Added transport revalidation, cherry-pick and test notes, including boundary-test mutation results, broader validation outcomes, and an independent review. The log records that retry and credential policies were unchanged and identifies publishing transport as the next step.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 2 files. (1 skipped: 1…	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main change: stabilizing large native Responses HTTP uploads by sending UTF-8 bytes.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 2 files. (1 skipped: 1 unsupported.)

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Actionable comments posted: 1

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• 🪄 Fix CodeRabbit comments on this PR

🤖 Prompt to fix review comments

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Inline comments:
Review comments at
@docs-site/src/content/docs/reference/configuration/server.md:
- Around line 82-85: Update the upload description in the configuration docs to
state that the final HTTP send converts native ChatGPT Responses and compact
JSON string bodies only when their UTF-8 size is at least 1 MiB. Keep the
existing explanation of Bun’s upload behavior and replay-refusal policy.

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ℹ️ Review info

⚙️ Run configuration

• Configuration used: Repository: lidge-jun/opencodex/.coderabbit.yaml
• Review profile: ASSERTIVE
• Plan: Advanced
• Run ID: 05e062c2-a61e-433f-ab89-21948c88272b

📥 Commits

Reviewing files that changed from the base of the PR and between 9f89b72 and 82507bd.

📒 Files selected for processing (10)

• devlog/_plan/261003_release_lane_a/000_plan.md
• devlog/_plan/261003_release_lane_a/001_evidence.md
• devlog/_plan/261003_release_lane_a/010_native_upload.md
• devlog/_plan/261003_release_lane_a/020_messages_context.md
• devlog/_plan/261003_release_lane_a/030_review_publication.md
• docs-site/src/content/docs/reference/configuration/server.md
• src/server/responses/fetch-helpers.ts
• structure/transports/byte-accounting.md
• structure/transports/responses.md
• tests/responses/responses-fetch-helpers-boundary.test.ts

Included review availability: This review used your included allowance. Your plan provides up to 10 included reviews per hour; 5 remain after this review.

[lidge-jun]

Owner-authorized progressive maintainer integration into dev for the release stabilization train. This records an integration decision, not a self-approval.

Reviewed head db094c49c7cce13500b1f1f63678f174261fc9af: the final physical HTTP send converts only canonical native Responses/compact string bodies at least 1 MiB to identical UTF-8 bytes. I independently checked the runtime delta and boundary regressions: destination rewriting, egress/headers, cancellation, manual redirects and no-replay behavior remain intact; no credential or account policy is changed. The docs threshold correction is included and the review thread is resolved. Explicit security review: no blocking finding in this scoped boundary change; lane independent implementation/security review also passed.

Required scoped CI passed: https://github.com/lidge-jun/opencodex/actions/runs/37130246238, attempt 1, pull_request event. All four Linux test shards, gates, storage/API jobs, docs/structure, Docker, keyring and selected npm-global jobs actually succeeded. Checkout log binds the tested PR head above to dev base 9f89b7265b754eb681215ad327fc9459af37b9e1. Full macOS/Windows suites were scope-skipped here and remain required in the final integrated lane=all run, not claimed as passing now. Local evidence independently inspected: 199 pass / 1 runtime-specific skip, plus six failing mutation regressions with conversion removed; typecheck/privacy/structure/docs passed.

Live actor/base/head and repository review helper were revalidated; no unresolved review threads or maintainer objections. Preserve the branch while child #6516 targets it. Source #6508 remains a carried contribution with retained credit; coordinator will reconcile its disposition after landing.