fix(core): treat 503 Service Unavailable as retryable quota error

[sehoon38]

Summary

Treat 503 Service Unavailable as a retryable quota error in classifyGoogleError. This ensures that temporary service interruptions are handled similarly to rate limits, allowing the system to retry the operation instead of failing immediately.

Details

• Updated classifyGoogleError in packages/core/src/utils/googleQuotaErrors.ts to check for status code 503.
• If status is 503, it returns a RetryableQuotaError.
• Added a corresponding unit test in packages/core/src/utils/googleQuotaErrors.test.ts.

Related Issues

Fixes #19656

How to Validate

Run npm test -w @google/gemini-cli-core -- src/utils/googleQuotaErrors.test.ts to verify the new test case.

Pre-Merge Checklist

• Updated relevant documentation and README (if needed)
• Added/updated tests (if needed)
• Noted breaking changes (if any)
• Validated on required platforms/methods:
  • MacOS
    • npm run

[gemini-cli]

Hi @sehoon38, thank you so much for your contribution to Gemini CLI! We really appreciate the time and effort you've put into this.

We're making some updates to our contribution process to improve how we track and review changes. Please take a moment to review our recent discussion post: Improving Our Contribution Process & Introducing New Guidelines.

Key Update: Starting January 26, 2026, the Gemini CLI project will require all pull requests to be associated with an existing issue. Any pull requests not linked to an issue by that date will be automatically closed.

Thank you for your understanding and for being a part of our community!

[gemini-code-assist]

Summary of Changes

Hello @sehoon38, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the error handling mechanism by treating 503 Service Unavailable responses as retryable quota errors. This change improves the system's robustness by allowing automatic retries for temporary service interruptions, aligning their treatment with existing rate limit error handling.

Highlights

• Error Handling: Implemented logic to classify HTTP 503 (Service Unavailable) errors as RetryableQuotaError within the classifyGoogleError function, ensuring temporary service interruptions are handled gracefully.
• Test Coverage: Added a new unit test to verify that 503 errors are correctly identified and returned as RetryableQuotaError instances.

Changelog

• packages/core/src/utils/googleQuotaErrors.test.ts
  • Added a test case to ensure 503 Service Unavailable errors are classified as RetryableQuotaError.
  • Updated the description of an existing test to reflect the new 503 handling.
• packages/core/src/utils/googleQuotaErrors.ts
  • Introduced a new conditional block to detect HTTP status code 503 and return a RetryableQuotaError.

Activity

• The author has added/updated tests to cover the new error handling logic.
• The changes have been validated on MacOS using npm run.

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[gemini-cli]

Hi there! Thank you for your contribution to Gemini CLI.

To improve our contribution process and better track changes, we now require all pull requests to be associated with an existing issue, as announced in our recent discussion and as detailed in our CONTRIBUTING.md.

This pull request is being closed because it is not currently linked to an issue. Once you have updated the description of this PR to link an issue (e.g., by adding Fixes #123 or Related to #123), it will be automatically reopened.

How to link an issue:
Add a keyword followed by the issue number (e.g., Fixes #123) in the description of your pull request. For more details on supported keywords and how linking works, please refer to the GitHub Documentation on linking pull requests to issues.

Thank you for your understanding and for being a part of our community!

[gemini-code-assist]

Code Review

The pull request correctly identifies and addresses the need to treat 503 Service Unavailable errors as retryable quota errors. The changes include modifying classifyGoogleError to handle status code 503 and adding a corresponding unit test. The code changes are well-implemented and the test case adequately covers the new functionality.

[github-actions]

Size Change: +309 B (0%)

Total Size: 25.1 MB

ℹ️ View Unchanged

Filename	Size	Change
./bundle/gemini.js	25.1 MB	+309 B (0%)
./bundle/sandbox-macos-permissive-open.sb	890 B	0 B
./bundle/sandbox-macos-permissive-proxied.sb	1.31 kB	0 B
./bundle/sandbox-macos-restrictive-open.sb	3.36 kB	0 B
./bundle/sandbox-macos-restrictive-proxied.sb	3.56 kB	0 B
./bundle/sandbox-macos-strict-open.sb	4.82 kB	0 B
./bundle/sandbox-macos-strict-proxied.sb	5.02 kB	0 B

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