fix(antigravity): surface Google 429 quota exhaustion instead of retrying it

[shuv1337]

Intent

The captain approved resuming the issue backlog (2026-10-04): "triage the ~22 Cursor draft PRs first, then small batches", and later answered yes that shuvbro triage review counts as the first review for these Cursor PRs. The read-only triage report at ~/repos/shuvbro/data/triage-cursor-shuvcode/report.md identifies #427 (fix(antigravity): surface Google 429 quota instead of retrying it, issue #404) as fix-then-land. P1: packages/antigravity-plugin/src/wire.ts:390-393 on the PR head lets fiveHourWindow fall back to ANY group 5h bucket when the failed model group is missing, so a Gemini RESOURCE_EXHAUSTED/RATE_LIMIT_EXCEEDED with only an exhausted Claude/GPT summary is classified QuotaExceeded, retryable=false - a transient throttle becomes terminal (reproduced with the real parser). Required: use only the quota group demonstrably belonging to the failed model; a missing/unrecognized group must not borrow another group exhaustion; keep explicit QUOTA_EXHAUSTED and affirmative long-window handling; add cross-group and missing-group regressions plus a response-hook integration regression proving the full body and classification reach the session. The referenced triage section says the full-body parsing and synthetic Google ErrorInfo are otherwise aligned with the quota-plugin group format; current default does not explain non-ok responses or classify quota_exhausted, so the issue fix remains needed after correcting model-group attribution.

What Changed

• The Antigravity plugin's http.response hook now handles failed responses to rewritten Cloud Code requests. It parses the full error body, including nested Google errors and SSE data: payloads. On a 429 it also requests a best-effort quota readout from the retrieveUserQuotaSummary endpoint, which is new in oauth.ts. It then sends back a Google-format error with the Cloud Code status, the message, a summary of each quota window and a synthetic ErrorInfo reason.

• A RESOURCE_EXHAUSTED error becomes non-retryable QUOTA_EXHAUSTED only in these cases:

  • The error carries an explicit QUOTA_EXHAUSTED reason.
  • The failed model's own quota group (Gemini, or Claude/GPT) has an exhausted 5h bucket. A missing or unrecognized group never takes another group's exhaustion.
  • The error message points to a long reset window (5h, or 1 hour or more).

  All other RESOURCE_EXHAUSTED errors remain retryable throttles. @opencode/ai provider-error classification now treats the quota_exhausted reason as a quota code.

• Added tests in packages/antigravity-plugin/test/error.test.ts, packages/ai/test/provider-error.test.ts and the new packages/core/test/session-antigravity-error.test.ts:

  • parser and classification tests, including cross-group and missing-group regressions
  • a response-hook integration test that checks the full body and classification reach the session

  The plugin README also documents this behavior.

Risk Assessment

✅ Low: The 5h-window lookup now returns only the bucket for the failed model's group ("gemini:5h" or "3p:5h") and never falls back to another group. Explicit QUOTA_EXHAUSTED and long-window message handling are kept. Cross-group, missing-group, unknown-model, and response-hook regressions cover the required behavior, and the group naming matches packages/quota-plugin/src/google.ts.

Testing

After installing dependencies, I ran the targeted antigravity wire tests, the core session response-hook integration test and the ai classifier test; all pass. An A/B run against the pre-fix wire.ts shows the 6 new cross-group and missing-group regressions failing before the fix, which confirms they reproduce the P1. A temporary scratch test also drove the real plugin response hook with the quota-summary fetch path turned on. For a Gemini throttle, an exhausted Claude/GPT or unknown group stays RATE_LIMIT_EXCEEDED, and only an exhausted Gemini group becomes QUOTA_EXHAUSTED. These are unit and in-process integration results, not live results. Nothing ran against a real live Google 429, because that needs a real Antigravity OAuth account in a throttled or exhausted state against the hardcoded cloudcode-pa endpoint. There is no UI surface, so no screenshots were taken. The worktree is clean.

• Live validation: ⚠️ inconclusive - 0 of 6 scenarios driven live against the product

Scenario	Result	Live	Evidence
Gemini 429 RATE_LIMIT_EXCEEDED with only an exhausted Claude/GPT 5h bucket stays a retryable throttle (cross-group adversarial)	⏸️ untested	no	The prior payload established no live result. Only the real parser and plugin hook were exercised, with a stubbed quota-summary fetch (error.test.ts, hook-crossgroup-scratch.log, A/B log); nothing ran…
Missing or unrecognized quota group, or unknown model, does not borrow another group's exhaustion	⏸️ untested	no	The prior payload established no live result. Only unit and in-process tests with stubbed quota summaries ran; there was no live Google Antigravity account to drive it.
Exhausted matching group (Gemini 5h for Gemini, 3p 5h for Claude/GPT) is classified QUOTA_EXHAUSTED	⏸️ untested	no	The prior payload established no live result. Only unit and in-process tests with stubbed quota summaries ran; a live run needs an Antigravity account whose quota is exhausted.
Explicit QUOTA_EXHAUSTED reason and affirmative 5h-reset messages still become non-retryable QuotaExceeded	⏸️ untested	no	The prior payload established no live result. Only unit and integration tests ran (error.test.ts, session-antigravity-error.test.ts, provider-error.test.ts); there was no live Google account.
Full >500-char 429 body passes through the http.response hook and its classification reaches the session (RequestExecutor.httpFailure)	⏸️ untested	no	The prior payload established no live result. The plugin hook ran in-process with fixture credentials (session-antigravity-error.test.ts), not against Google.
Real shuvcode session on a Google Antigravity account hitting a live 429 shows the quota message and stops retrying (or retries on a throttle)	⏸️ untested	no	Needs a real Google Antigravity OAuth subscription in a throttled or quota-exhausted state. The Cloud Code endpoint (cloudcode-pa) is hardcoded, so it can't be pointed at a local fake. To run it, log…

Evidence: Wire fix diff (fiveHourWindow no longer falls back to any group)

diff --git a/packages/antigravity-plugin/src/wire.ts b/packages/antigravity-plugin/src/wire.ts
index de052e029a..2a895bea23 100644
--- a/packages/antigravity-plugin/src/wire.ts
+++ b/packages/antigravity-plugin/src/wire.ts
@@ -389,8 +389,9 @@ function quotaWindowID(bucket: Record<string, unknown>) {
 
 function fiveHourWindow(windows: readonly QuotaWindow[], modelID: string | undefined) {
   const name = (modelID ?? "").toLowerCase()
-  const preferred = name.includes("claude") || name.includes("gpt") ? "3p:5h" : "gemini:5h"
-  return windows.find((window) => window.id === preferred) ?? windows.find((window) => window.id.endsWith(":5h"))
+  const preferred =
+    name.includes("claude") || name.includes("gpt") ? "3p:5h" : name.includes("gemini") ? "gemini:5h" : undefined
+  return windows.find((window) => window.id === preferred)
 }
 
 function messageIsLongQuota(message: string | undefined) {

Evidence: A/B: pre-fix wire.ts fails the 6 cross/missing-group regressions

(fail) Cloud Code 429 bodies > does not borrow quota from an unrelated or missing group: {"modelID":"gemini-3.8-flash-high","groups":[{"displayName":"Claude + GPT","buckets":[{"window":"5h","remainingFraction":0}]}]} [0.11ms]
(fail) Cloud Code 429 bodies > does not borrow quota from an unrelated or missing group: {"modelID":"claude-sonnet-4-6","groups":[{"displayName":"Gemini models","buckets":[{"window":"5h","remainingFraction":0,"resetTime":"2026-08-14T18:00:00Z"},{"window":"weekly","remainingFraction":0.4,"resetTime":"2026-08-20T00:00:00Z"}]}]} [0.02ms]
(fail) Cloud Code 429 bodies > does not borrow quota from an unrelated or missing group: {"modelID":"gpt-oss-120b","groups":[{"displayName":"Gemini models","buckets":[{"window":"5h","remainingFraction":0,"resetTime":"2026-08-14T18:00:00Z"},{"window":"weekly","remainingFraction":0.4,"resetTime":"2026-08-20T00:00:00Z"}]}]} [0.01ms]
(fail) Cloud Code 429 bodies > does not borrow quota from an unrelated or missing group: {"modelID":"gemini-3.8-flash-high","groups":[{"displayName":"Unknown models","buckets":[{"window":"5h","remainingFraction":0}]}]} [0.02ms]
(fail) Cloud Code 429 bodies > does not borrow quota from an unrelated or missing group: {"modelID":"unknown-model","groups":[{"displayName":"Gemini models","buckets":[{"window":"5h","remainingFraction":0,"resetTime":"2026-08-14T18:00:00Z"},{"window":"weekly","remainingFraction":0.4,"resetTime":"2026-08-20T00:00:00Z"}]}]} [0.02ms]
(fail) Cloud Code 429 bodies > does not borrow quota from an unrelated or missing group: {"groups":[{"displayName":"Gemini models","buckets":[{"window":"5h","remainingFraction":0,"resetTime":"2026-08-14T18:00:00Z"},{"window":"weekly","remainingFraction":0.4,"resetTime":"2026-08-20T00:00:00Z"}]}]} [0.01ms]
 10 pass
 6 fail

Evidence: Response hook with quota summary: rewritten bodies per summary group for a Gemini throttle

Claude + GPT exhausted -> reason RATE_LIMIT_EXCEEDED (retryable) Gemini models exhausted -> reason QUOTA_EXHAUSTED Unknown models exhausted -> reason RATE_LIMIT_EXCEEDED (retryable)

bun test v1.4.2 (744846f84)

test/zz-scratch-crossgroup.test.ts:
SCENARIO Claude + GPT -> {"error":{"code":429,"message":"RESOURCE_EXHAUSTED: Resource has been exhausted (e.g. check quota). 3p:5h remainingFraction=0 resetTime=2026-10-05T03:00:00Z","status":"RESOURCE_EXHAUSTED","details":[{"@type":"type.googleapis.com/google.rpc.ErrorInfo","reason":"RATE_LIMIT_EXCEEDED"}]}}
SCENARIO Gemini models -> {"error":{"code":429,"message":"RESOURCE_EXHAUSTED: Resource has been exhausted (e.g. check quota). gemini:5h remainingFraction=0 resetTime=2026-10-05T03:00:00Z","status":"RESOURCE_EXHAUSTED","details":[{"@type":"type.googleapis.com/google.rpc.ErrorInfo","reason":"QUOTA_EXHAUSTED"}]}}
SCENARIO Unknown models -> {"error":{"code":429,"message":"RESOURCE_EXHAUSTED: Resource has been exhausted (e.g. check quota). group-0:5h remainingFraction=0 resetTime=2026-10-05T03:00:00Z","status":"RESOURCE_EXHAUSTED","details":[{"@type":"type.googleapis.com/google.rpc.ErrorInfo","reason":"RATE_LIMIT_EXCEEDED"}]}}

 3 pass
 0 fail
 30 expect() calls
Ran 3 tests across 1 file. [470.00ms]

Evidence: Session integration test output

bun test v1.4.2 (744846f84)

 3 pass
 0 fail
 27 expect() calls
Ran 3 tests across 1 file. [375.00ms]

Evidence: Antigravity wire test output

bun test v1.4.2 (744846f84)

 16 pass
 0 fail
 34 expect() calls
Ran 16 tests across 1 file. [58.00ms]

- Outcome: ⚠️ 1 warning across 1 run (1m39s)

Pipeline

Updates from git push no-mistakes

✅ **intent** - passed

✅ No issues found.

⏭️ **Rebase** - skipped

Step was skipped.

✅ **Review** - passed

✅ No issues found.

⚠️ **Test** - 1 warning

• ⚠️ live validation verdict: inconclusive (0 of 6 scenarios were driven live against the product); untested: Gemini 429 RATE_LIMIT_EXCEEDED with only an exhausted Claude/GPT 5h bucket stays a retryable throttle (cross-group adversarial), Missing or unrecognized quota group, or unknown model, does not borrow another group's exhaustion, Exhausted matching group (Gemini 5h for Gemini, 3p 5h for Claude/GPT) is classified QUOTA_EXHAUSTED, Explicit QUOTA_EXHAUSTED reason and affirmative 5h-reset messages still become non-retryable QuotaExceeded, Full >500-char 429 body passes through the http.response hook and its classification reaches the session (RequestExecutor.httpFailure), Real shuvcode session on a Google Antigravity account hitting a live 429 shows the quota message and stops retrying (or retries on a throttle)
• Live validation: ⚠️ inconclusive - 0 of 6 scenarios driven live against the product

Scenario	Result	Live	Evidence
Gemini 429 RATE_LIMIT_EXCEEDED with only an exhausted Claude/GPT 5h bucket stays a retryable throttle (cross-group adversarial)	⏸️ untested	no	The prior payload established no live result. Only the real parser and plugin hook were exercised, with a stubbed quota-summary fetch (error.test.ts, hook-crossgroup-scratch.log, A/B log); nothing ran…
Missing or unrecognized quota group, or unknown model, does not borrow another group's exhaustion	⏸️ untested	no	The prior payload established no live result. Only unit and in-process tests with stubbed quota summaries ran; there was no live Google Antigravity account to drive it.
Exhausted matching group (Gemini 5h for Gemini, 3p 5h for Claude/GPT) is classified QUOTA_EXHAUSTED	⏸️ untested	no	The prior payload established no live result. Only unit and in-process tests with stubbed quota summaries ran; a live run needs an Antigravity account whose quota is exhausted.
Explicit QUOTA_EXHAUSTED reason and affirmative 5h-reset messages still become non-retryable QuotaExceeded	⏸️ untested	no	The prior payload established no live result. Only unit and integration tests ran (error.test.ts, session-antigravity-error.test.ts, provider-error.test.ts); there was no live Google account.
Full >500-char 429 body passes through the http.response hook and its classification reaches the session (RequestExecutor.httpFailure)	⏸️ untested	no	The prior payload established no live result. The plugin hook ran in-process with fixture credentials (session-antigravity-error.test.ts), not against Google.
Real shuvcode session on a Google Antigravity account hitting a live 429 shows the quota message and stops retrying (or retries on a throttle)	⏸️ untested	no	Needs a real Google Antigravity OAuth subscription in a throttled or quota-exhausted state. The Cloud Code endpoint (cloudcode-pa) is hardcoded, so it can't be pointed at a local fake. To run it, log…

• bun install (worktree had no node_modules)
• cd packages/antigravity-plugin && bun test test/error.test.ts (16 pass)
• cd packages/core && bun test test/session-antigravity-error.test.ts (3 pass: QUOTA_EXHAUSTED→QuotaExceeded non-retryable, 5h-reset message→QuotaExceeded, plain throttle→RateLimit retryable, full >500-char body reaches the session)
• cd packages/ai && bun test test/provider-error.test.ts -t "Google 5h" (1 pass)
• A/B: git show 0d0fc791b4:packages/antigravity-plugin/src/wire.ts swapped in, then error.test.ts reran (6 cross-/missing-group regressions fail before the fix), then restored with git checkout HEAD -- wire.ts
• Temporary scratch variant of the session integration test (deleted afterwards): drives the real GoogleAntigravityPlugin http.response hook with the quota-summary fetch enabled and a stubbed retrieveUserQuotaSummary returning an exhausted Claude+GPT / Gemini / Unknown group for a Gemini model

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