fix(core-tools): show ellipsis on multi-line edit snippets

[mc856]

Summary

EditToolInvocation.getDescription() now appends ... when the displayed
snippet hides content from the user: either the first line exceeds 30 characters,
or the edit spans multiple lines. This keeps multi-line edits with a short first
line from looking like a single-line change in the confirmation UI.

The snippet helper also treats \r\n, \r, and \n as line breaks before
rendering, so CRLF input does not leave a carriage return in terminal output. It
truncates with Array.from() to avoid splitting simple multi-byte characters
such as emoji.

Details

The old logic displayed only the first \n-delimited line, but decided whether
to append ... from the full string length. That missed cases where additional
lines were hidden behind a short first line. After review, the helper now also
avoids the CRLF case where split('\n') could leave \r in the rendered
snippet.

Related Issues

Fixes #28110
Fixes #28109

How to Validate

npx vitest run packages/core/src/tools/edit.test.ts -t getDescription
# 10 passed

npx vitest run packages/core/src/tools/edit.test.ts
# 74 passed

npx eslint packages/core/src/tools/edit.ts packages/core/src/tools/edit.test.ts --max-warnings 0
# passed

git diff --check upstream/main...HEAD
# passed

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-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 resolves a display issue in the edit tool's confirmation UI where multi-line snippets were incorrectly presented without an ellipsis if the first line was short. The changes ensure that users are properly notified of hidden content in multi-line edits. Additionally, the PR improves test suite stability across different operating systems and removes legacy bot configuration files that are no longer in use.

Highlights

• Ellipsis Logic Fix: Updated the snippet generation logic in EditToolInvocation to ensure an ellipsis is displayed whenever a snippet contains multiple lines, regardless of the first line's length.
• Regression Testing: Added comprehensive unit tests for the getDescription method to cover boundary conditions and multi-line edit scenarios, addressing issues Bug: EditTool getDescription snippet doesn't show ellipsis for multi-line edits with short first lines #28110 and Bug: EditTool description snippet incorrectly truncates multi-line strings #28109.
• Test Environment Stability: Improved test reliability on macOS by canonicalizing the temporary directory path using fs.realpathSync, preventing path resolution failures.
• Cleanup: Removed obsolete Gemini CLI bot agent and skill configuration files from the repository.

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[github-actions]

📊 PR Size: size/M

• Lines changed: 151
• Additions: +145
• Deletions: -6
• Files changed: 2

[gemini-code-assist]

Code Review

This pull request refactors the description snippet generation in EditTool to correctly append an ellipsis when content is hidden, adds comprehensive unit tests for these scenarios, and canonicalizes the temporary directory path in tests to resolve macOS path mismatches. It also removes several obsolete agent/skill definition files. The reviewer recommended handling CRLF line endings to prevent terminal rendering corruption and using Array.from() to avoid splitting multi-byte Unicode characters during truncation.

[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'.

Once approved, the evaluation results will be posted here automatically.

[mc856]

Force-pushed to remove an unintended 5-file deletion under tools/gemini-cli-bot/.gemini/ — those files were missing from my local snapshot of upstream (the directory is matched by the repo's **/.gemini/ gitignore, but the files were tracked before that rule was added). Restored them verbatim from upstream and re-pushed. The PR now only contains the intended edit.ts + edit.test.ts changes (+124/-7).