fix(core): normalize line endings in diff context snippets

[mikemikimike]

Summary

• Normalize CRLF and CR line endings before computing diff context snippets.
• Add a regression test covering a CRLF file with one changed line.

Fixes #29130

Testing

• npm run test:ci
• npm run typecheck --workspace @google/gemini-cli-core
• npm exec prettier -- --check packages/core/src/tools/diff-utils.ts packages/core/src/tools/diff-utils.test.ts
• npm exec eslint packages/core/src/tools/diff-utils.ts packages/core/src/tools/diff-utils.test.ts
• git diff --check

[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 addresses an issue where inconsistent line endings caused incorrect diff context generation. By normalizing line endings to LF before processing, the tool now correctly identifies logical changes without being affected by platform-specific newline characters.

Highlights

• Line Ending Normalization: Updated the diff utility to normalize CRLF and CR line endings to LF before performing line-by-line comparisons.
• Regression Testing: Added a new test case to ensure that CRLF line endings do not cause false positives when calculating diff context snippets.

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[github-actions]

📊 PR Size: size/S

• Lines changed: 28
• Additions: +26
• Deletions: -2
• Files changed: 2

[github-actions]

🛑 Action Required: Evaluation Approval

Steering changes have been detected in this PR. To prevent regressions, a maintainer must approve the evaluation run before this PR can be merged.

Maintainers:

1. Go to the Workflow Run Summary.
2. Click the yellow 'Review deployments' button.
3. Select the 'eval-gate' environment and click 'Approve'.

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[gemini-code-assist]

Code Review

This pull request normalizes line endings to \n in diff-utils.ts before performing line diffing to prevent CRLF differences from being flagged as changes, and adds a corresponding unit test. The reviewer pointed out a potential inconsistency where normalizedNew is normalized to \n but newLines is still split using /\r?\n/ on the original content, which could lead to mismatched line counts or out-of-bounds errors. The reviewer suggested splitting normalizedNew by \n instead.

[mikemikimike]

Updated the fix based on review feedback.

• Use normalizedNew.split('\\n') so diff indexes and extracted lines use the same normalized representation.
• Add a regression test for standalone CR line endings.

Local validation:

• npx vitest run packages/core/src/tools/diff-utils.test.ts --coverage=false — 9/9 passed.
• Docker: pathReader.test.ts — 22/22 passed.
• Docker: sandboxManager.integration.test.ts — 34/34 passed with bubblewrap and privileged namespace support.
• Core typecheck — passed.
• Core build — passed.
• Prettier and ESLint for the changed files — passed.

The broader Core suite was also exercised in Docker; its remaining environment-sensitive failures were isolated to sandbox namespace availability before bubblewrap was installed. The targeted suites above pass after the environment was corrected.

[gemini-code-assist]

Code Review

This pull request updates the diff utility functions in packages/core/src/tools/diff-utils.ts to normalize line endings (CRLF and CR to LF) before computing line differences and splitting the content. This ensures that changing only the line-ending style does not incorrectly trigger diffs. Corresponding unit tests have been added to packages/core/src/tools/diff-utils.test.ts to verify CRLF and CR line-ending handling. There are no review comments, so I have no feedback to provide.

[mikemikimike]

当前 head 已落实该建议：newLines 改为基于 normalizedNew.split('\n')，并补充 standalone CR 回归测试。关闭此旧线程。