fix(google): allow structured output for Gemini models on Cloud Code Assist

[agentHits]

Summary

Closes #4669

Allow structured output (text.format / response_format) for Gemini models on Cloud Code Assist (google-antigravity).

• Lift the blanket Cloud Code Assist refusal in src/adapters/google.ts when modelId starts with gemini-.
• Route structured output into generationConfig.responseMimeType: "application/json" and generationConfig.responseJsonSchema inside envelope.request.generationConfig. The existing compileGoogleWireBody whitelist already passes both keys into the wire envelope.
• Retain explicit fail-closed refusal for non-Gemini models (such as Claude) served through Cloud Code Assist ("google cloud-code-assist structured output is not implemented by opencodex for non-Gemini models — remove response_format or route this model through a direct provider").
• Preserve existing refusals for image-capable models (responseModalities conflict) and schemaless json_schema.
• Update structure/providers/google.md and expand tests/adapters/google/google-structured-output.test.ts to cover Gemini-on-CCA (json_schema and json_object) and Claude-on-CCA rejection.

Verification

Ran focused checks covering the changed subsystems:

• bun test tests/adapters/google/google-structured-output.test.ts (12 pass, 0 fail across 23 assertions, covering AI Studio, Vertex, Gemini-on-CCA, and explicit refusals for Claude-on-CCA, image-capable, and schemaless json_schema)
• bun run structure:check (structure/ SSOT checks passed)
• bun run typecheck (tsc --noEmit exited with code 0)

Full bun test was not run per repository instructions for scoped adapter changes.

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.

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• All CI tests are green on my local testing.

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Summary by CodeRabbit

• Bug Fixes
  • Structured-output settings now work for Gemini models routed through Cloud Code Assist.
  • JSON object and schema-based output configurations are correctly applied to supported Gemini requests.
  • Unsupported non-Gemini and image-capable models continue to be rejected with clear guidance to use a direct provider.
  • Cloud Code Assist requests now preserve the appropriate generation settings without exposing unsupported top-level configuration.

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• tests/adapters/google/google-structured-output.test.ts

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📝 Walkthrough

Walkthrough

Cloud Code Assist now passes structured-output settings for Gemini models through envelope.request.generationConfig. Non-Gemini models, including Claude, remain rejected. Tests cover supported wire formats and rejection cases.

Changes

Cloud Code Assist structured output

Layer / File(s)	Summary
Gemini structured-output routing src/adapters/google.ts, structure/providers/google.md	At src/adapters/google.ts:799-806, rejection now applies only to non-Gemini model IDs. At structure/providers/google.md:65-71, structured-output settings are documented under envelope.request.generationConfig.
Structured-output validation tests/adapters/google/google-structured-output.test.ts	The tests add the required Cloud Code Assist project and envelope type. They verify nested JSON Schema and JSON-object settings, and rejection for Claude and gemini-3-pro-image-preview.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Feature · Severity of issue fixed: Medium

Merge Risk: ⚪ Minimal · up to 3169d

Supported Gemini structured output is routed into the Cloud Code Assist request envelope, while unsupported model cases remain rejected. No actionable merge-blocking issue is established.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 2 files.	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 and concisely describes the main change: enabling structured output for Gemini models on Cloud Code Assist. It matches the implementation and stated objectives.
Linked Issues check	✅ Passed	Issue #4669 requires json_schema and json_object support for Gemini models on Cloud Code Assist. In src/adapters/google.ts around line 799, the refusal now applies only when googleMode is `clo…
Out of Scope Changes check	✅ Passed	The changes stay within issue #4669. src/adapters/google.ts changes the Cloud Code Assist structured-output gate and its error message. tests/adapters/google/google-structured-output.test.ts adds …

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[lidge-jun]

리뷰 · 우선순위 69 / 80

이 PR은 초안(draft) 이고, 이슈 #4669를 닫으려는 작은 버그 수정이다. 지금 dev(HEAD aa91958e3, 패키지 2.56.0, #4661 라운드3 + import-resolution 가드 이후)에서 Google 어댑터는 Cloud Code Assist(googleMode === "cloud-code-assist", 곧 google-antigravity)로 들어오는 모든 text.format / structured output 요청을 로컬에서 바로 거절한다. 그래서 Gemini 모델로 보낸 json_schema / json_object 도 네트워크에 나가기 전에 HTTP 400이 난다. 이슈에 적힌 메시지가 바로 그 거절이다.

고치는 방식은 단순하다. src/adapters/google.ts 의 거절 조건을 “CCA면 전부 거절”에서 “CCA이면서 모델 id가 gemini- 로 시작하지 않으면 거절”로 좁힌다. Gemini면 기존과 같이 generationConfig.responseMimeType = "application/json" 과 (스키마가 있으면) responseJsonSchema 를 채운다. CCA 경로는 그 flat body를 그대로 envelope.request 안으로 감싸므로, 키는 envelope.request.generationConfig 아래에 실린다. compileGoogleWireBody / compileGenerationConfig 화이트리스트에 이미 두 키가 있어서, 어댑터만 열어 주면 와이어에서 다시 떨어지지 않는다.

비 Gemini(예: Claude-on-CCA)는 계속 명시적으로 거절한다. 침묵하면 스키마 없는 일반 문장이 “성공”처럼 보이기 때문이다. 이미지 출력 모델(responseModalities 충돌)과 스키마 없는 json_schema 거절도 그대로 둔다. 테스트는 CCA Gemini의 envelope 위치 검사 두 개와 Claude-on-CCA 거절 이름 변경을 추가했고, CCA fixture에 project: "test-project" 를 넣었다. 지금 dev 코드는 CCA 경로에서 provider.project 가 없으면 바로 throw 하므로, 이 fixture 보강은 맞다. structure/providers/google.md 도 “CCA 전부 미구현”에서 “CCA의 비 Gemini만 미구현”으로 고쳤다.

types.ts / config.ts 모놀리스를 건드리지 않는다. 소비자 import 경로 불변식과도 무관하다. #4655 파사드 열차나 #4546 과는 겹치지 않는 독립 어댑터 버그다. 초안 체크리스트(로컬 CI 전부 초록, 최신 dev rebase, CodeRabbit/Codex 정리, ready)는 아직 비어 있다. 리뷰 시점 status check는 hygiene 계열 5개가 SUCCESS 였고 mergeable 이지만 draft라 BLOCKED 상태다.

라인 / 경로 수준으로 보면 큰 거짓 버그는 없고, 확인·주의 포인트만 적는다.

라인 799 근처 (src/adapters/google.ts) - 거절 게이트가 parsed.modelId.startsWith("gemini-") 이다. 같은 파일의 CCA thought/include 경로는 routedModelId / wireModelId 에 /^gemini-/ 를 쓴다. 오늘 시드 모델은 둘 다 gemini-… 라 맞지만, 나중에 alias·rename 이 wire만 바꾸고 parsed id는 안 바꾸면 게이트와 wire 판정이 어긋날 수 있다
라인 809 이후 - 이미지 출력 모델 거절은 CCA 완화 뒤에도 그대로 실행된다. Gemini-on-CCA 이미지 모델에 structured output을 열지 않는 불변식은 유지된다. 다만 그 조합을 덮는 CCA 전용 회귀 테스트는 없다
tests/.../google-structured-output.test.ts - envelope 위치(request.generationConfig)와 Claude 거절은 잘 잡는다. 업스트림 CCA가 실제로 schema를 강제하는지는 로컬 buildRequest 단위로는 증명되지 않는다(의도적 fail-open이 아니라 “와이어 키가 나간다” 증명)
structure/providers/google.md - 문서와 코드 거절 범위가 다시 맞춰졌다
에러 문구 - “AI Studio or Vertex”에서 “a direct provider”로 바뀌었다. 의미는 통하지만, 사용자에게 구체 우회 경로가 조금 덜 보인다

메인테이너의 판단이 필요한 지점

• draft를 ready로 올리기 전에 “와이어 키가 envelope에 실리는 것”만으로 충분한지, 아니면 한 번의 수동/스테이징 CCA 호출로 schema 강제까지 볼지
• 게이트를 parsed.modelId 기준으로 둘지, CCA의 routedModelId/wireModelId 와 맞출지
• 이미지 출력 Gemini-on-CCA + textFormat 거절을 테스트에 한 줄 더 넣을지(필수는 아님)
• [Provider compatibility] Cloud Code Assist rejects structured output on Gemini models #4669 재현이 Codex Desktop helper의 response_format 경로라면, 머지 후 그 클라이언트에서 한 번만 스모크할지

너의 추천
초안이므로 지금은 머지하지 말고, 작성자 체크리스트를 채운 뒤 ready로 전환하는 쪽이 맞다. 코드 방향 자체는 dev 에 맞아 보인다: Gemini-on-CCA만 열고 비 Gemini는 fail-closed, 기존 이미지/스키마리스 거절 유지, 테스트·structure 문서가 같은 이야기를 한다. ready 전에 (1) gemini- 판정을 parsed vs wire 중 어디에 둘지 한 줄 확인하고 (2) 가능하면 image-capable Gemini-on-CCA 거절 테스트를 하나 보태면 더 안전하다. types/config 스플릿 때문에 닫을 PR은 아니다. 충돌 없이 rebase 가능하면 유지하고, ready 후 머지하면 된다.

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Actionable comments posted: 1

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Inline comments:
In `@tests/adapters/google/google-structured-output.test.ts`:
- Around line 60-80: Add a Cloud Code Assist regression test alongside the
existing CCA structured-output tests, using model gemini-3-pro-image-preview and
the image-capable configuration. Assert that buildRequest rejects structured
output with the exact error message “cannot combine image output with structured
output,” covering the googleMode: "cloud-code-assist" admission path.

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[Ingwannu]

Requesting changes on exact head 11e343e5f877b21aa6f0b2ce52048baf0e34d788. The Gemini-only Cloud Code Assist admission is the right direction and is preferable to the broader duplicate #4693, but two focused test boundaries should be fixed before this becomes a merge candidate.

1. Add the missing CCA image-capable regression. The new condition now lets gemini-* pass the CCA gate and relies on the following isImageCapableModel guard to refuse the conflicting JSON constraint. Exercise a Cloud Code Assist provider with gemini-3-pro-image-preview (or the current canonical image fixture) and assert the exact cannot combine image output with structured output failure. Without this, the branch-specific ordering that keeps image generation fail-closed is not pinned.

2. The two new envelope assertions parse into Record<string, any>. Please use a narrow local envelope type or an unknown record helper for request.generationConfig. These tests are the contract proof for where CCA places the schema; any makes a misspelled or non-object intermediate path compile silently and weakens that proof.

After those changes, rerun the focused Google structured-output suite and exact-head hosted checks. I am not authorizing or treating the current external CI as merge evidence because the head needs to change.

[agentHits]

@Ingwannu Both requested test boundaries are on 22965dc2d3303217a6da25042997c41ca026c8c3 (current head; 0 commits behind dev):

1. CCA image-capable regression: an image-capable Cloud Code Assist model refuses the structured-output conflict asserts the exact cannot combine image output with structured output failure for gemini-3-pro-image-preview on a Cloud Code Assist provider.
2. Envelope assertions now parse as a local CloudCodeAssistEnvelope instead of Record<string, any>.

Local verification on that exact head:

• bun test tests/adapters/google/google-structured-output.test.ts — 12 pass / 0 fail
• bun run typecheck — clean

I did not change the parsed.modelId.startsWith("gemini-") gate versus wireModelId; today's seed ids still match, and I am leaving that unless you want it aligned.

Full bun run test on this machine still fails in unrelated host-sensitive files (Codex runtime discovery with a local install; Linux bubblewrap treating the Bun binary as a non-private executable). None of those files are in this PR. I am not ticking the local-CI / ready boxes until hosted CI is green on this head.

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[honjow]

Complementing the probe posted on #4669 — this is a correctness note on the key this PR carries, not a review of the gate itself.

Lifting the blanket refusal for gemini-* is the right direction and matches what I reproduced locally. The problem is the destination key: on the Cloud Code Assist envelope, generationConfig.responseJsonSchema is silently ignored.

I probed {base}/v1internal:generateContent directly with the same envelope opencodex builds, a real Antigravity OAuth token and IDE User-Agent, gemini-3.8-flash-medium, and a prompt that never mentions JSON or the schema ("Summarize the history of the Eiffel Tower"). The schema required verdict_code with enum ["ZQ7-ALPHA"]:

request.generationConfig	Constrained?	Output
responseMimeType only (control)	no	prose
+ responseJsonSchema (object, and JSON-stringified)	no	prose, no verdict_code
+ responseSchema (Gemini typed form)	yes	{"verdict_code": "ZQ7-ALPHA"}

Reproduced across repeat runs and on gemini-3.7-flash as well. responseJsonSchema behaves exactly like the control — HTTP 200, schema dropped. That silently restores the "unconstrained prose returned as success" failure the refusal gate exists to prevent, which is the one outcome the existing comment says must not regress.

Two concrete follow-ups this implies:

1. Wire key. responseSchema (typed Gemini form: OBJECT/STRING/ARRAY/INTEGER/NUMBER/BOOLEAN; lowercase types also worked in my probe, uppercase is the documented form) is the key CCA honors. It is not currently in the compileGenerationConfig whitelist in google-wire-compiler.ts, so it needs adding there too — otherwise the adapter sets a key that is dropped before the wire, the same trap the existing comment already warns about for responseMimeType/responseJsonSchema.

2. The json_schema test assertion on CCA. "Gemini-on-CCA carries responseMimeType and responseJsonSchema inside envelope.request" pins the key that does not enforce. It would pass while the real request still returns prose. Worth re-pinning to responseSchema after the adapter change, and ideally asserting responseJsonSchema is absent on the CCA path so the two paths cannot silently drift back together.

For the Claude-on-CCA refusal this PR keeps: that path is not simply "unimplemented". Claude-on-CCA answers responseSchema with a synthetic functionCall named json_mode holding the conforming args ({"verdict_code":"ZQ7-ALPHA"}), rather than text — responseJsonSchema and responseMimeType alone both return prose. If that path is ever admitted, the json_mode call has to be unwrapped into assistant text or the client sees a bogus tool call. Keeping the refusal for now is defensible; "unimplemented" just undersells what is actually there.

Environment: opencodex 2.56.0, provider google-antigravity (googleMode: "cloud-code-assist"), CCA models probed gemini-3.8-flash-medium, gemini-3.7-flash-medium, claude-sonnet-4-6. Requests and outputs redacted.

[lidge-jun]

Landed via #4719 at f6843be.

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