fix(core): restrict "System: Please continue" invalid stream retry to Gemini 2 models

[SandyTao520]

Summary

Restrict the "System: Please continue." invalid stream retry to Gemini 2 models only. Non-Gemini-2 models (e.g., Gemini 3) no longer trigger this retry mechanism on InvalidStream events.

Details

The processTurn method in GeminiClient previously injected a "System: Please continue." message whenever an InvalidStream event was received and getContinueOnFailedApiCall() was true, regardless of the model. This change adds an isGemini2Model(modelToUse) guard so the retry only fires for Gemini 2.x models.

• Added isGemini2Model import from config/models.js
• Gated the invalid stream retry condition on isGemini2Model(modelToUse)
• Updated existing tests to use 'gemini-2.0-flash' as the routed model
• Added a new test confirming non-Gemini-2 models skip the retry

Related Issues

#18007

How to Validate

1. Run npm test -w @google/gemini-cli-core -- src/core/client.test.ts
2. Verify the three InvalidStream-related tests pass:
   • should recursively call sendMessageStream with "Please continue." when InvalidStream event is received for Gemini 2 models
   • should not retry with "Please continue." when InvalidStream event is received for non-Gemini-2 models
   • should stop recursing after one retry when InvalidStream events are repeatedly received

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
    • npx
    • Docker
    • Podman
    • Seatbelt
  • Windows
    • npm run
    • npx
    • Docker
  • Linux
    • npm run
    • npx
    • Docker

[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.

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[gemini-cli]

Hi @SandyTao520, 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, 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 refines the GeminiClient's error handling by restricting the 'System: Please continue.' retry behavior to only Gemini 2 models. This change prevents unintended retry attempts for newer models, such as Gemini 3, which do not require this specific recovery mechanism, thereby improving the accuracy and efficiency of API interactions.

Highlights

• Conditional Retry Logic: The 'System: Please continue.' retry mechanism for InvalidStream events is now exclusively applied to Gemini 2 models, preventing unintended retries for newer models.
• Model Version Check: The isGemini2Model utility function was integrated into the GeminiClient to gate this retry logic, ensuring it only activates for the intended model versions.
• Enhanced Test Coverage: Existing tests were updated to reflect the Gemini 2 model routing, and a new test case was added to explicitly confirm that non-Gemini-2 models bypass this retry mechanism.

Changelog

• packages/core/src/core/client.test.ts
  • Updated test description to specify Gemini 2 models for the InvalidStream retry.
  • Configured the router service to return 'gemini-2.0-flash' for relevant retry tests.
  • Adjusted expected ModelInfo event values in assertions to reflect 'gemini-2.0-flash'.
  • Added a new test to confirm that non-Gemini-2 models do not trigger the InvalidStream retry.
  • Ensured the recursive retry test also uses a Gemini 2 model.
• packages/core/src/core/client.ts
  • Imported the isGemini2Model helper function.
  • Modified the InvalidStream handling logic to conditionally apply the 'Please continue.' retry only if the modelToUse is a Gemini 2 model.

Activity

• Added/updated tests to cover the new conditional retry logic.
• Validated changes on MacOS using npm run.

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[gemini-code-assist]

Code Review

This pull request correctly restricts the InvalidStream retry mechanism to only apply to Gemini 2 models. The change in GeminiClient is straightforward, adding a check with isGemini2Model. The accompanying test updates are thorough, ensuring existing tests for the retry logic now use a Gemini 2 model, and a new test has been added to verify that non-Gemini 2 models correctly skip this retry logic. The changes are well-implemented and address the issue effectively.

[github-actions]

Size Change: +6.55 kB (+0.03%)

Total Size: 25.8 MB

Filename	Size	Change
./bundle/gemini.js	25.3 MB	+6.55 kB (+0.03%)

ℹ️ View Unchanged

Filename	Size
./bundle/node_modules/@google/gemini-cli-devtools/dist/client/main.js	221 kB
./bundle/node_modules/@google/gemini-cli-devtools/dist/src/_client-assets.js	227 kB
./bundle/node_modules/@google/gemini-cli-devtools/dist/src/index.js	11.5 kB
./bundle/node_modules/@google/gemini-cli-devtools/dist/src/types.js	132 B
./bundle/sandbox-macos-permissive-open.sb	890 B
./bundle/sandbox-macos-permissive-proxied.sb	1.31 kB
./bundle/sandbox-macos-restrictive-open.sb	3.36 kB
./bundle/sandbox-macos-restrictive-proxied.sb	3.56 kB
./bundle/sandbox-macos-strict-open.sb	4.82 kB
./bundle/sandbox-macos-strict-proxied.sb	5.02 kB

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