fix(a2a-server): normalize CRLF line endings to LF in getProposedContent

[luisfelipe-alt]

Summary

This PR resolves an issue where the side-by-side diff view in Gemini Code Assist
(GCA) on Windows fails to highlight any changes when code is generated or
modified. The root cause is a line ending mismatch (CRLF vs. LF) in the local
agent backend (a2a-server package) that prevents text replacement from
matching correctly.

Details

On Windows, local files default to CRLF (\r\n) line endings, while the model
generates search and replacement blocks using standard LF (\n) line endings.

When GCA requests a diff view, the local agent backend intercepts the replace
tool call to pre-calculate the proposed content. However, it reads the local
file without normalizing its line endings. This causes safeLiteralReplace to
fail the substring match and silently return the original content unmodified,
resulting in an empty diff view.

This PR updates packages/a2a-server/src/agent/task.ts to normalize the raw
file content to LF (\n) before applying the replacement, aligning its
behavior with the core package's EditTool.

Related Issues

How to Validate

1. Run npm install and npm run build to compile the monorepo.
2. Run the newly added unit test to verify the fix:

   npx vitest run packages/a2a-server/src/agent/task.test.ts

3. Verify that all 18 tests in task.test.ts pass successfully, including the
   new getProposedContent (CRLF Line Ending Normalization) test.
4. Run the linter to ensure no style regressions:

   npm run lint

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 addresses a functional issue in the local agent backend where text replacement operations failed on Windows environments. By normalizing file content to LF line endings before processing, the system now correctly matches search and replacement blocks generated by the model, ensuring that diff views are properly populated.

Highlights

• Line Ending Normalization: Implemented CRLF to LF normalization in the getProposedContent method to ensure compatibility with Windows file systems.
• Bug Fix: Resolved an issue where side-by-side diffs failed to display on Windows due to line ending mismatches preventing successful substring matching.
• Regression Testing: Added a new unit test in task.test.ts to verify that content replacement works correctly when files contain CRLF line endings.

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[github-actions]

📊 PR Size: size/M

• Lines changed: 118
• Additions: +113
• Deletions: -5
• Files changed: 2

[gemini-code-assist]

Code Review

This pull request introduces CRLF line ending normalization in packages/a2a-server/src/agent/task.ts by converting \r\n to \n in the raw file content before applying replacements, and adds corresponding unit tests. The reviewer correctly pointed out that old_string and new_string should also be normalized to LF to prevent replacement failures if they contain CRLF line endings.

[luisfelipe-alt]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces CRLF line ending normalization in Task.getProposedContent to ensure string replacements succeed regardless of the file's line endings, along with corresponding unit tests. The reviewer feedback correctly points out that unconditionally converting CRLF files to LF in the proposed content can cause full-file diff mismatches in IDEs. It is recommended to detect the original line endings and restore CRLF if it was present, and to update the new unit tests to assert that CRLF line endings are preserved.

[luisfelipe-alt]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces CRLF line ending normalization in Task.getProposedContent to ensure consistent replacement behavior regardless of the file's line endings. It normalizes the file content, the search string, and the replacement string to LF before applying the replacement, and restores CRLF line endings if they were originally present. Additionally, unit tests have been added to verify this behavior. There are no review comments, so I have no feedback to provide.

[DavidAPierce]

LGTM