fix(codex): honor scoped cooldowns in subagent fallback

[luvs01]

Summary

• Resolve the Pool account independently for each subagent fallback candidate's routed Codex quota scope, so a shared-model preview cannot incorrectly reject Spark or another scoped candidate.
• Apply account-gated model entitlements during preview and availability checks. Account-qualified primaries remain pinned, pooled Daybreak fallbacks select only an entitled account, and unentitled fixed selectors are skipped.
• Keep public preview helpers side-effect-free: they do not move account cursors, bind affinity, or acquire quota probes. Live request selection atomically reserves a due probe only after the chosen candidate passes every predicate, then transfers that exact account/scope reservation to final authentication.
• When concurrent spawns reach the same due model-scoped cooldown, let exactly one retain the native candidate while the loser advances to its healthy routed fallback instead of failing with a late local 429.
• Fence native-main credential reads across initial selection, final authentication, and encrypted-task recovery. Recovery retains a fresh lifecycle admission and a fresh account preview.
• Honor the ChatGPT host circuit before entitlement discovery and recheck it immediately before joining or starting a roster-discovery flight. Circuit-fenced misses remain uncached, so recovery can observe newly available entitlements.
• Preserve half-open recovery by atomically reserving the host probe while deciding whether to keep the original unqualified Pool primary. If another request owns that probe, the concurrent spawn can use a healthy routed fallback instead of ending in a late 503.
• Preserve public route ownership when a fallback adds, removes, or changes an account selector, even when both identities resolve to the same physical model.
• Resolve the effective fallback chain once per logical spawn and reuse one lazy entitlement/account-preview factory in both selection passes. The preview admission is released even when agent-role fallback discovery fails.
• Defer account-gated entitlement discovery until ordered selection reaches the first gated Pool candidate. Earlier healthy routed or native candidates avoid catalog I/O; after discovery, selection restarts from the chain head with a fresh clock.

Maintainer follow-up

The implementation covers the requested and reviewed concurrency and identity cases:

1. A cooled fixed primary can fall through to pooled gpt-daybreak-blue-latest, and only the entitled Pool account is previewed and authenticated.
2. An unentitled fixed Daybreak selector is skipped even when the primary account is entitled.
3. A ChatGPT circuit that opens during credential work prevents both new roster fetches and attachment to a stale in-flight discovery request, allowing a healthy routed primary to continue.
4. The single half-open host lease is reserved at the preservation decision and reused by final pre-auth admission. A concurrent request that does not own it remains network-fenced and selects its healthy routed fallback.
5. team/gpt-5.6-sol → gpt-5.6-sol reroutes from the cooled fixed account to the healthy Pool account although the physical model slug is unchanged.
6. Initial and encrypted-task recovery passes share the same fail-closed entitlement and reroute boundaries while retaining separately acquired lifecycle admissions.
7. Healthy routed and encrypted-task native candidates ahead of a gated fallback complete selection without entitlement discovery. When discovery is required, the post-await pass restarts from the chain head so newly healthy earlier candidates are reconsidered.
8. A due scoped quota probe is now claimed atomically during live selection and adopted only when account, scope, lease ID, and cooldown generation still match. Pre-auth refusal releases it, while a newer 429 fences stale adoption and preserves the newer cooldown.

All applicable Codex and CodeRabbit review threads are resolved on the current head.

Verification

Focused checks were run on exact head 76af70ca916e234755b891564924786def1ce835 with Bun 1.4.0-canary.1 (9fcdea80b):

• tests/subagent-fallback-handle-responses.test.ts — 46 passed, 2 Darwin-only skips, 0 failed, 229 assertions
• tests/subagent-model-fallback.test.ts — 58 passed, 0 failed, 121 assertions
• tests/codex-model-entitlements.test.ts — 9 passed, 0 failed, 25 assertions
• focused total — 113 passed, 2 Darwin-only skips, 0 failed, 375 assertions
• bun run typecheck — passed
• bun run privacy:scan — passed
• git diff --check and commit whitespace validation — passed
• independent implementation and regression reviews — no remaining actionable findings; the concurrency regression also failed deterministically on the preceding head with [200, 429]

The repository-wide suite was not duplicated locally; changed-path coverage and the relevant static gates above are green. The two skipped relay-selection cases are Darwin-only by their test guard.

Exact base: c44e43f00f1b8001f30292067324fb419e5ffc86
Exact head: 76af70ca916e234755b891564924786def1ce835

Checklist

• Scope stays focused and avoids unrelated cleanup.
• Docs or release notes were updated when needed. This restores an internal routing contract and adds no public API or configuration surface.
• Security-sensitive changes were reviewed for secrets, auth, and unsafe defaults. Entitlement discovery respects host admission, lifecycle exclusions remain fail-closed, and route/probe ownership is fenced across fallback and authentication.

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📝 Walkthrough

Walkthrough

The change adds side-effect-free quota probe eligibility, entitlement-aware account previews, model-specific fallback routing, lifecycle-based account exclusion, host-circuit handling, and recovery-path reuse of these constraints.

Changes

Entitlement-aware subagent fallback

Layer / File(s)	Summary
Entitlement resolution and lifecycle exclusions src/codex/model-entitlements.ts, src/codex/auth-context.ts, tests/codex-model-entitlements.test.ts	Entitlement resolution supports credential snapshot injection and excluded accounts. Authentication context excludes the main account when native-main reads are forbidden.
Scoped probe and fallback routing src/codex/routing.ts, src/codex/subagent-model-fallback.ts	Fallback routing previews model-eligible accounts and checks model-scoped or account-wide probe leases. Host-circuit APIs distinguish closed, cooldown, and probe-due states.
Response entitlement wiring src/server/responses/core.ts	Response handling resolves entitlements, preserves required host probes, shares timestamped account previews, and applies the constraints during primary and recovery selection.
Fallback and recovery coverage tests/subagent-model-fallback.test.ts, tests/subagent-fallback-handle-responses.test.ts	Tests cover scoped cooldowns, entitlement-gated routes, fixed-account handling, lifecycle exclusions, host-circuit admission, and recovery re-previewing.

Estimated code review effort: 4 (Complex) | ~45 minutes

Merge Risk: 🔵 Low · up to 9a921

The cooldown and entitlement routing changes are supported by passing focused checks and static validation. The PR is mergeable with owner awareness because the request path still repeats synchronous fallback-chain filesystem scans that can add latency, while duplicated primary and recovery gating logic could diverge in future maintenance.

Possibly related PRs

• lidge-jun/opencodex#2101: Adds related Codex model entitlement checks and eligible-account filtering.

Suggested reviewers: lidge-jun

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	Docstring check was indeterminate for this PR — some files could not be analyzed in time. Not blocking.
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.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main change: applying scoped cooldowns during Codex subagent fallback routing.

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⏳ DRAFT

• hygiene: unsponsored_surface.

What to do

• Fix unsponsored_surface — This changes an authentication, workflow, release-automation, or dependency surface. MAINTAINERS.md requires security review for these; ask a maintainer to apply maintainer-sponsored once they have reviewed it. Paths: src/codex/auth-context.ts.

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[lidge-jun]

리뷰 · 우선순위 56 / 80

설명: 이 PR 은 자식 에이전트가 다른 모델로 넘어갈 때, 그 모델의 할당량 칸에 맞는 계정만 고르게 한다. 지금 CURRENT dev HEAD 는 4f41a8e93 이다. 이번 시간에 origin/dev 는 그대로다. 새 머지는 없다. 착지는 여전히 2396 사용량 CLI 오늘 비용이다. package.json 은 2.27.0 이다. src/config.ts 는 3975줄이다. src/runtime 폴더는 지금 HEAD 에 없다. 지금 HEAD 의 src/codex/subagent-model-fallback.ts 176줄 resolveRouteFallbackAccountId 는 이미 박힌 계정이 없으면 미리보기 계정 하나를 그대로 쓴다. 234줄 isSubagentModelUnavailable 은 그 계정으로 건강을 본다. 260줄은 안 박힌 풀 길에서 계정 전체 식힘만 본다. 모델 칸 식힘은 안 본다. src/server/responses/core.ts 2386줄 previewCodexAccountForRequest 는 첫 모델의 칸만 넣는다. 그래서 솔이 식어도 스파크 칸은 다른 계정이 비어 있는데, 미리보기가 솔 칸의 계정 A 를 스파크에도 씌운다. A 의 스파크가 막혀 있으면 자식이 실패한다. A 의 계정 전체가 식으면 스파크를 건너뛰고 먼 길로 간다. 이 PR 은 후보마다 그 모델 칸으로 계정을 다시 미리 본다. 미리보기는 계정 순서도 안 옮기고 임대도 안 잡는다. 계정에 묶인 네이티브 모델은 권한 표를 미리보기와 가능 검사에 같이 넣는다. 박힌 선택기는 그대로 고정이다. 권한 없는 계정은 닫힌다. 암호로 감싼 자식 작업을 되살린 뒤 두 번째 고름에도 같은 규칙을 쓴다. src/codex/routing.ts 는 칸 임대를 읽기만 하는 함수를 더한다. 실제 임대는 인증 길에 남긴다. 시험은 공유에서 스파크로 넘어갈 때 계정 B 를 고르는지, 데이브레이크 권한이 있는 계정만 남는지, 암호 복구 두 번째 고름이 새 칸을 다시 보는지 잠근다. 작성자 로컬은 미리보기 8개와 칸/고정/빈/권한 12개, typecheck, privacy:scan 통과라고 적었다. 드래프트가 아니다. bug 와 review-ready 라벨이 있다. 체크리스트 네 칸이 채워져 있다. 작성자는 luvs01 이다. 베이스는 지금 HEAD 와 같다. Closes 가 없다. GitHub 위생과 게이트는 READY 다. CodeRabbit 은 지적 없음이다. Cross-platform CI 권위는 아직일 수 있다. 사용자 길이로는 자식이 식은 칸의 계정으로 스파크를 고르는 구멍이라서 56. 카탈로그 팁은 Ox Alpha x-preview-f-free + deepseek-v4-flash-vision-exp. Cursor 정적 카탈로그는 opus-4-8-fast / opus-5-fast. 2334 CursorCredentialRouter 는 여전히 src/providers/cursor-pool.ts 모듈+테스트만 있고 어댑터에 연결되지 않았다. 2332 H2 는 discovery 전용. 2320 overflow + 2342 는 이미 dev. 2188 사이드카는 이미 dev. 2382 데스크톱 앱 재시작은 이미 dev. 2292 는 아직 연다.

src/codex/subagent-model-fallback.ts 라인 176 - 지금 HEAD 는 박힌 계정이 없으면 미리보기 계정 하나를 모든 후보에 쓴다
src/codex/subagent-model-fallback.ts 라인 260 - 안 박힌 풀 길은 계정 전체 식힘만 본다. 모델 칸 식힘은 건너뛴다
src/server/responses/core.ts 라인 2386 - 미리보기는 첫 모델 칸만 넣는다. 스파크 후보는 솔 칸의 계정을 그대로 받는다
src/codex/routing.ts 새 canAcquireCodexQuotaScopeProbeLease - 칸 임대를 읽기만 한다. 실제 임대는 인증 길에 남긴다
tests/subagent-fallback-handle-responses.test.ts - 공유에서 스파크로 넘어갈 때 계정 B 를 고르는지, 복구 두 번째 고름이 새 칸을 다시 보는지 잠근다
GitHub CI - 위생과 게이트는 READY. Cross-platform CI 권위는 아직일 수 있다. 작성자 로컬은 20개 통과

메인테이너의 판단이 필요한 지점

• GitHub 시험이 아직이면 기다릴지. 작성자 로컬은 이미 통과라고 적었다
• 권한 표를 미리보기와 실제 인증에서 두 번 읽는다. 한 번으로 줄일지
• 이 구멍을 이슈로 남길지. 본문에 Closes 가 없다

너의 추천
GitHub 시험이 초록이면 머지한다. 가드를 더 넓히지 말 것. 미리보기는 읽기만 하게 둔다. 실제 임대는 인증 길에 남긴다. types.ts/config.ts 스플릿과 겹치지 않는다. 라벨은 그대로 둔다. 프리뷰 배포가 아니다.

이 댓글은 grok-bot이 작성했습니다

[Ingwannu]

The candidate-scoped preview direction is correct, but the current handleResponses gate leaves one account-qualified primary path outside the entitlement boundary.

subagentFallbackNeedsModelEntitlements(parsed, config) correctly scans the fallback chain, but core.ts resolves the entitlement snapshot only when the initial route has route.codexAccountId === undefined. If a thread starts on an account-qualified primary (for example team/gpt-5.6-sol) and that fixed candidate is skipped by cooldown/health, a later pooled or fixed gpt-daybreak-blue-latest fallback is evaluated without modelEligibleAccountIdsForModel. The unit helper can enforce entitlements when a callback is passed, but the production call never creates that callback for this route shape. It can therefore skip a healthy entitled pool account because an unentitled preview account is cooled, or admit an unentitled fixed fallback and fail only during final auth.

Please remove the initial-route account-id condition from entitlement snapshot setup; the need should be derived from the actual fallback chain, not the primary route ownership. Add handleResponses regressions for an account-qualified primary that falls through to (1) a pooled account-gated model where only another pool account is entitled and (2) an unentitled fixed account-gated selector that must be skipped. Keep preview side-effect-free and final authentication authoritative.

After the fix, rebase onto current dev, rerun the two focused fallback suites, typecheck, and exact-head CI. No broader routing refactor is needed.

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Actionable comments posted: 4

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Inline comments:
In `@src/codex/auth-context.ts`:
- Around line 395-397: Update ResolveCodexAuthContextOptions so
resolveCodexModelEntitlements uses the typeof resolveCodexModelEntitlements
signature, allowing the existing config and excludeAccountIds arguments in
resolveCodexAuthContext. Ensure injected entitlement resolvers that inspect
credentials apply excludeAccountIds before selecting or using the fenced
__main__ credential.

In `@src/server/responses/core.ts`:
- Around line 2389-2444: Extract the duplicated entitlement-filter and
account-preview setup into one factory returning modelEligibleAccountIds and
accountPreview, parameterized by config, poolAffinityKey,
nativeMainReadsForbidden, selection options, and the entitlement resolver.
Update src/server/responses/core.ts lines 2389-2444 to use the factory, and
replace the duplicate construction at lines 2527-2581 with the same factory
call; preserve the fresh recoverySelectionAdmission and its finally release.

In `@tests/subagent-fallback-handle-responses.test.ts`:
- Around line 1050-1059: Replace the as never casts on both fake admission
leases with the real admission lease option type used by
codexAccountSelectionForTurn, preserving the existing release and
beginCodexAccountSelection behavior while ensuring the fake’s returned selection
object is checked against the production contract.
- Around line 1112-1119: Update the recovery-clock setup in the test using the
default fallback TTL: import and use DEFAULT_SUBAGENT_MODEL_FALLBACK_POLL_MS
when calculating currentNow, advancing now by that interval plus one;
alternatively, pass an explicit TTL to the xai/grok-4.5 noteSubagentModelFailure
call.

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Inline comments:
In `@src/codex/subagent-model-fallback.ts`:
- Around line 619-642: Hoist fallback-chain resolution into a reusable helper
and update subagentFallbackNeedsModelEntitlements and applySubagentModelFallback
to accept the precomputed chain instead of resolving it independently. In the
response handling flow, resolve the chain once per request and reuse it for
entitlement checks, fallback application, and the encrypted-recovery pass,
preserving existing fallback behavior.

In `@src/server/responses/core.ts`:
- Around line 2577-2636: Extract the shared entitlement and account-preview
construction into a factory accepting config, route, poolAffinityKey, the
entitlement resolver, and selection options, returning modelEligibleAccountIds,
preservePrimaryForHostProbe, and accountPreview. Update both the primary and
recovery passes to use this factory, preserving their existing fallback and
preview behavior. Keep recoverySelectionAdmission acquisition and its finally
release unchanged so recovery still re-reads drain state.

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[luvs01]

@Ingwannu The account-qualified entitlement paths requested in your review are now covered on eff80d7bc13a: a cooled fixed primary selects only an entitled pooled Daybreak account, and an unentitled fixed Daybreak selector is skipped. The later scoped-probe concurrency finding is also fixed with atomic reservation, stale-generation fencing, and pre-auth release coverage. All current review threads are resolved; focused Bun 1.4 checks are 113 passed / 2 Darwin-only skipped, with typecheck and privacy scan green. Author-side work and all 4 readiness boxes are complete. The remaining unsponsored_surface draft gate and review decision require maintainer action.

[luvs01]

Closing this draft because the work is being delivered as small review units under #2509. #2515 is the candidate-scoped Pool-account preview unit, including recovery-path parity. Entitlement, probe-ownership, and other authentication/lifecycle changes remain separate review units and will use the repository's sponsorship and review gates. Thanks for the detailed review.