fix(openai-chat): forward caller-selected service tier

[Yuxin-Qiao]

Summary

• Preserve an explicit parsed.options.serviceTier value when serializing OpenAI-compatible Chat Completions requests.
• Add a regression test covering service_tier: "priority" on the outbound /chat/completions body.
• This fixes the request-path half of [Bug][High impact] Routed Fast mode is hidden and openai-chat silently drops service_tier #1504; routed catalog capability publication remains tracked separately by [Feature]: expose speed/service-tier capabilities for eligible custom providers and routed models #1436.
• Rebased onto current dev@cbbfdd8773e68a5dc2391ddeb32f33a225373c1a; current head: ab72f5441e1b.

Refs #1504
Refs #1436

Verification

• bun test --isolate --max-concurrency 1 tests/openai-chat-hardening.test.ts tests/service-tier-capability.test.ts — 50 passed, 0 failed, 84 assertions.
• bun run typecheck — passed on the rebased head.
• bun run privacy:scan — passed.
• git diff --check — passed.
• A repository-wide bun run test result is not claimed; the suite contains current baseline/environment failures unrelated to this narrow serializer change.

Checklist

• Scope stays focused and avoids unrelated cleanup.
• Docs or release notes were updated when needed; this is an internal request serialization fix.
• Security-sensitive changes were reviewed for secrets, auth, and unsafe defaults.
• Local CI is green.
• Branch is on the latest dev commit.
• Correct Codex and CodeRabbit findings are fixed.
• Ready-for-review confirmation is present.

Review readiness checklist

This PR stays in draft until every box below is ticked. Tick all four boxes once the requirements are met:

• All CI tests are green on my local testing.

• I pushed my PR to the latest dev commit.

• I resolved all correct Codex and CodeRabbit findings.

• My PR is ready for review.

[coderabbitai]

Important

Review skipped

Draft detected.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: 6716cb2d-eb4b-49b9-b59a-b9b4550c27c5

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[github-actions]

✅ Deterministic PR hygiene checks passed.

[github-actions]

⏳ DRAFT

• review readiness checklist open (1/4 boxes ticked).

What to do

• Tick all four boxes in the PR description once you're done (currently 1/4).

Review readiness checklist

• ⬜ All CI tests are green on my local testing.
• ✅ I pushed my PR to the latest dev commit.
• ⬜ I resolved all correct Codex and CodeRabbit findings.
• ⬜ My PR is ready for review.

1/4 boxes ticked.

This PR stays in draft until every box above is ticked.

[Yuxin-Qiao]

PR #1521 includes this Chat Completions serialization fix (commit b7cf9df4f) together with the broader #1436 capability/catalog/runtime work. I am leaving this narrow PR open for maintainer choice; if #1521 is accepted, this PR can be closed as superseded.

[Yuxin-Qiao]

Rebased the fork branch onto current dev@d5824814853eea68ceb4417403b22000a935cef8; new head is a3535941d15b. Post-rebase local proof: Chat/service-tier focused suite 50/50, 84 assertions; typecheck, privacy scan, and diff check passed. GitHub hygiene, target, label, and resolve checks are green. Keeping this Draft pending maintainer choice/review; #1521 carries the same Chat serialization fix.

[Yuxin-Qiao]

Rebased and force-with-lease pushed onto current dev@cbbfdd8773e68a5dc2391ddeb32f33a225373c1a; new head is ab72f54. Fresh local proof: Chat/service-tier focused suite 50/50, 84 assertions; typecheck, privacy scan, and diff check passed. The PR description is updated; keeping Draft pending maintainer choice/review, with #1521 carrying the same serializer fix.

[Ingwannu]

The narrow serializer change is valid and appropriately scoped: parsed.options.serviceTier is currently captured upstream and this adapter silently drops it. The focused test proves the outbound Chat Completions body now preserves the caller-selected value.

However, #1521 contains the same serializer change together with the provider/model capability resolver and catalog/runtime gating. Keeping both open creates two competing landing paths for the same line. I recommend treating #1512 as the minimal fallback only: leave it draft while #1521 is reviewed, and close it as superseded if #1521 is accepted. If the broader capability PR is rejected or split, this two-file patch is a reasonable standalone candidate after exact-head CI and readiness completion.