[Bug]: Untracked review diff spawns one git process per untracked file with no cap

[samkelly880]

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/server

Steps to reproduce

1. Open a project whose working tree has a very large number of untracked files (e.g. a generated directory not covered by .gitignore, with tens of thousands of files).
2. Open the review diff for that project so the server calls review.getDiffPreview. The untracked fallback is used when the unified working-tree diff fails, and large repos are the likeliest to hit it.
3. Watch the process table.

Expected behavior

The untracked part of the review diff is bounded: a capped number of files are diffed, and the result is marked truncated beyond that, as the tracked diff already is.

Actual behavior

readUntrackedReviewDiffs spawns one git diff --no-index process per untracked file, with no cap on the file count (apps/server/src/vcs/GitVcsDriverCore.ts:2177-2224 on main, the Effect.forEach(untrackedPaths, …, { concurrency: 4 }) at :2192).

The only bound is WORKSPACE_FILES_MAX_OUTPUT_BYTES = 120_000 (:55) on the NUL-separated path list from git ls-files --others. At 2 bytes minimum per path, that still allows ~60,000 paths, so up to ~60,000 git processes from one request. Concurrency 4 makes it a long stall, not a spike. Those calls also hold permits on the shared git process semaphore, which delays every other git operation in the meantime. Combined output is not bounded either: each file is capped individually, but the joined result is not.

Impact

Major degradation or frequent failure

Version or commit

main @ c0995d2

Environment

Linux; found by code reading and reproduced in a fork (T3o).

Logs or stack traces

No response

Workaround

Add the untracked directory to .gitignore.

---

A reference fix from our fork: e35c6ac. It diffs at most 200 untracked files, stops once combined output reaches the tracked-diff cap, and marks the result truncated, with a test in GitVcsDriverCore.test.ts.

[juliusmarminge]

Note

Grok responding on behalf of Julius.

This was fixed on main by #10822 (aae361c, merged 2026-09-16). That change removed readUntrackedReviewDiffs and the per-file git diff --no-index Effect.forEach path; untracked review diffs now go through listUntracked → prepareReviewIndex → one unified tracked diff, so the uncapped process spawn you describe is gone on current main (8ed276c).

Your tip c0995d2 still had the old fallback — please re-check on latest main. Closing as already fixed. If you still hit unbounded git process spawn on current main, reopen with a repro against that SHA.