[ENHANCEMENT] Include deleted files in "lines removed" count so net LOC reflects file deletions

[raf202]

Problem (one or two sentences)

When the AI deletes files during refactors, those deleted files are not counted in the "lines removed" metric. That hides real reductions in code size and prevents seeing the true net lines of code change per iteration.

Context (who is affected and when)

Developers using Roo Code to review AI-generated edits and refactors. Happens whenever the AI deletes one or more files as part of a diff or refactor. Most visible during large refactors where files are removed rather than line-by-line edits.

Desired behavior (conceptual, not technical)

Count removed lines from deleted files and add them to the "lines removed" metric so the displayed added/removed counts reflect the true net change in code size. Optionally provide a toggle in settings to make deleted files count or not towards the total.

Constraints / preferences (optional)

No response

Request checklist

• I've searched existing Issues and Discussions for duplicates
• This describes a specific problem with clear context and impact

Roo Code Task Links (optional)

No response

Acceptance criteria (optional)

No response

Proposed approach (optional)

No response

Trade-offs / risks (optional)

No response

[roomote-v0]

I've analyzed this issue and here's my proposed implementation plan:

Root cause: In src/core/tools/ApplyPatchTool.ts, the handleDeleteFile method creates a message without diffStats. The diff content is just a plain string like "File will be deleted: path/to/file" instead of a proper unified diff showing all lines as removals. As a result, the UI's FileChangesPanel sees diffStats as undefined for deleted files and excludes them from the +/- totals.

Proposed fix (3 files changed):

1. Add convertDeletedFileToUnifiedDiff to src/core/diff/stats.ts -- a new helper (inverse of the existing convertNewFileToUnifiedDiff) that takes a file's content and path and produces a unified diff where all lines are removals (old file has content, new file is empty).

2. Update handleDeleteFile in src/core/tools/ApplyPatchTool.ts:

   • Pass change.originalContent (already captured by apply.ts when parsing the patch) into handleDeleteFile
   • Use the new convertDeletedFileToUnifiedDiff to generate a proper unified diff from the original content
   • Compute diffStats from that diff using the existing computeDiffStats
   • Include diffStats in the ClineSayTool message so the UI picks it up

3. Add tests for the new convertDeletedFileToUnifiedDiff function in src/core/diff/__tests__/stats.spec.ts, and update the ApplyPatchTool tests to verify diffStats are included for delete operations.

This is a small, focused change. The UI side (FileChangesPanel, fileChangesFromMessages) already handles diffStats generically, so no frontend changes are needed. The net effect is that when the AI deletes a file, its lines will appear in the "-" (removed) count.

Please mention @roomote in a comment saying that you approve this plan, and I'll proceed with the implementation.