fix(server): handle files named HEAD in git status

[Lucenx9]

What Changed

Disambiguate HEAD as a Git revision when collecting working-tree numstat data. The status path now terminates revision arguments with -- and preserves the existing fallback for repositories that do not have an initial commit yet.

A focused integration test creates and modifies a tracked file named HEAD, then verifies that GitVcsDriver.statusDetails() reports its line counts.

Why

git diff HEAD --numstat treats HEAD as ambiguous when the worktree also contains a file with that name, causing Git status collection to fail with exit code 128. The explicit revision/path boundary keeps valid repositories reportable without changing normal status behavior.

Validation

• node_modules/.bin/vp test run apps/server/src/vcs/GitVcsDriverCore.test.ts — 48 passed
• node_modules/.bin/vp run --filter t3 typecheck
• Focused lint and format checks for both changed files

Checklist

• This PR is small and focused
• I explained what changed and why
• No UI changes
• No motion or interaction changes

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Implemented with OpenAI GPT-5.6 through the Codex harness in T3 Code.

Note

Fix git diff HEAD --numstat to handle files named HEAD in git status

• Adds a pathspec separator -- to the git diff HEAD --numstat invocation in statusDetails, preventing Git from misinterpreting path tokens and allowing files literally named HEAD to appear in working tree changes.
• Expands isUnbornHeadStderr in GitVcsDriverCore.ts to also match "bad revision 'head'" (case-insensitive), covering an additional Git error variant for unborn HEAD detection.

^{Macroscope summarized cdfbeee.}

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Note

Low Risk
Narrow VCS status fix with a regression test; normal repos are unchanged aside from the explicit -- on the diff invocation.

Overview
Fixes Git status collection when the worktree contains a tracked file named HEAD. statusDetails now runs git diff HEAD --numstat with a trailing -- so Git treats HEAD as the revision, not a pathspec.

isUnbornHeadStderr also recognizes bad revision 'head', so the existing unborn-HEAD numstat fallback still applies when appropriate.

An integration test commits a file named HEAD, modifies it, and asserts statusDetails reports the path and line counts.

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

[coderabbitai]

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[macroscopeapp]

Approvability

Verdict: Approved cdfbeee

Straightforward bug fix using standard git conventions. Adds -- separator to git diff commands to prevent files named 'HEAD' from being misinterpreted as the HEAD revision. Includes a test validating the fix.

^{You can customize Macroscope's approvability policy. Learn more.}