Detect file renames in review diffs

[jakeleventhal]

Verification

1. File rename with no changes

Git detects one rename and the viewer renders a single exact-original.ts → exact-renamed.ts entry with -0 +0 and no content hunk.

2. File rename with minimal changes

Git detects an 84% similar rename, so the viewer keeps one minimal-original.ts → minimal-renamed.ts entry and renders the -1 +1 content diff.

3. File rename with too many changes

The files are below Git's rename-similarity threshold, so the viewer correctly renders replaced-new.ts as an addition and replaced-original.ts as a deletion.

Summary

• enable Git rename detection for working-tree and branch review diffs
• include untracked rename destinations through an isolated temporary index without modifying the user's real index
• preserve content hunks when a renamed file also has minor edits

Root cause

Working-tree previews generated tracked and untracked patches separately. A normal filesystem rename therefore appeared as an unrelated deletion and addition because Git never saw both paths in the same comparison.

Impact

The diff viewer now renders qualifying file moves as one renamed file while still showing any content changes. Branch comparisons use the same explicit Git rename detection.

Validation

• pnpm exec vp test apps/server/src/vcs/GitVcsDriverCore.test.ts (27 tests)
• pnpm exec vp check
• pnpm exec vp run typecheck
• git diff --check

Note

Detect file renames in working-tree and branch-range review diffs

• Replaces the two-step working-tree diff (tracked HEAD diff + separate git diff --no-index per untracked file) with a single unified diff via the new readWorkingTreeReviewDiff function in GitVcsDriverCore.ts.
• The new function builds a temporary Git index, stages intent-to-add for untracked files, and runs a single patch diff with --find-renames and --minimal against HEAD (or an empty tree when no commits exist yet).
• Adds --find-renames to the branch-range diff so committed renames are also detected.
• Truncation now reflects a single diff operation rather than concatenated outputs.
• Behavioral Change: untracked files, staged index-only deletions, and renames are now included in the working-tree diff; the previous per-file /dev/null diff approach is removed.

^{Macroscope summarized ca811f5.}

---

Note

Medium Risk
Changes how review diffs are produced (temp index + intent-to-add staging); behavior shifts for untracked files, renames, and edge cases, though the real index is isolated and covered by new integration tests.

Overview
Review diff previews now build the dirty worktree patch in one Git comparison instead of merging git diff HEAD with per-untracked git diff --no-index output.

readWorkingTreeReviewDiff copies the real index into a temp GIT_INDEX_FILE, runs git add --intent-to-add -A, and diffs against HEAD (or an empty tree before the first commit) with --find-renames and --minimal, without touching the user's index. Branch-range previews get the same --find-renames flag on baseRef...HEAD.

Integration tests cover pre-first-commit untracked/staged files, unstaged and committed renames with edits, sparse-checkout scope, and staged index-only deletions.

^{Reviewed by Cursor Bugbot for commit ca811f5. Bugbot is set up for automated code reviews on this repo. Configure here.}

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[macroscopeapp]

Approvability

Verdict: Needs human review

This PR fundamentally changes how working tree review diffs are computed, replacing per-file untracked diff generation with a temporary index-based approach. This is a significant architectural change to core diff logic that affects the review workflow and warrants human review.

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[chatgpt-codex-connector]

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Reviewed commit: 0ac42fc27c

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[cursor]

Cursor Bugbot has reviewed your changes using high effort and found 1 potential issue.

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^{Reviewed by Cursor Bugbot for commit 0fc42d5. Configure here.}

[cursor]

add -A erases index-only changes

High Severity

The readWorkingTreeReviewDiff function's git add --intent-to-add -A command on the temporary index re-adds files that were git rm --cached but still exist in the working tree. This causes the working-tree review diff to incorrectly omit staged deletions and other staged-only index changes.

 

^{Reviewed by Cursor Bugbot for commit 0fc42d5. Configure here.}

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 0fc42d53cc

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• Mark a draft as ready
• Comment "@codex review".

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[chatgpt-codex-connector]

Preserve non-ignored index-only deletions

Here git add -h says -A adds changes from tracked and untracked files and -N records only the fact a path will be added, so this temp-index refresh no longer preserves an existing index-only deletion when the same path remains as a non-ignored untracked file. Fresh evidence beyond the prior ignored-file case: after git rm --cached f without adding f to .gitignore, this command turns the copied index into DA f, and the following git diff HEAD is empty if the file still matches HEAD (or shows a modification if it changed), whereas the real index represents a deletion to be committed; the review preview can therefore miss or misstate files being untracked.

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[chatgpt-codex-connector]

Keep tracked diffs when untracked repos cannot be added

Because git add -h confirms -A scans untracked files too, this command can fail before the diff is generated for an otherwise valid dirty worktree; for example, an untracked nested Git repository with no commit makes git add --intent-to-add -A -- . exit 128 (does not have a commit checked out). Since the caller converts any readWorkingTreeReviewDiff failure into an empty working-tree preview, the presence of that scratch nested repo hides unrelated tracked modifications that the old tracked git diff HEAD -- path still reported.

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