A git worktree never replays a checkout's cache entry for a task that lists the workspace root #902

Written by an AI agent (Claude) on behalf of @jasonkuhrt.

A task that lists the workspace root records each entry's name and kind in its fingerprint, and .git is one of those entries. In an ordinary checkout .git is a directory; in a git worktree it is a file that points at the main repository. So a cache entry recorded in a checkout never replays in a worktree of the same commit, and the reverse, though every file a task can read is the same. The miss reads:

○ cache miss: '.git' added in workspace root, executing

We share one remote cache between CI, which checks out with a .git directory, and developers and agents, who work in git worktrees. In a fresh worktree at our trunk's head (vite-plus 1.4.0), 56 of the 143 vp lint tasks that missed missed for this reason alone, against entries CI recorded for that commit. Linters, Vitest's project discovery and anything that resolves the workspace list the root, so most of our tasks carry the root listing.

Steps to reproduce

repro.sh <path to vt> runs a task that lists the workspace root in a checkout, adds a worktree of the same commit, copies the checkout's cache into it (standing in for a shared or remote cache), and runs the task there.

#!/usr/bin/env bash
set -euo pipefail
vt=$(cd "$(dirname "$1")" && pwd)/$(basename "$1")
work=$(mktemp -d)
cd "$work"

mkdir checkout && cd checkout
git init -q -b main
cat > package.json <<'JSON'
{ "name": "repro", "private": true }
JSON
cat > vite-task.json <<'JSON'
{
  "tasks": {
    "list-root": {
      "command": "node -e \"console.log(require('fs').readdirSync('.').length)\"",
      "cache": true
    }
  }
}
JSON
echo node_modules > .gitignore
git add -A && git -c user.name=r -c user.email=r@r commit -qm init

echo "== checkout: first run"
"$vt" run list-root
echo "== checkout: second run"
"$vt" run list-root

git worktree add -q ../worktree
mkdir -p ../worktree/node_modules/.vite
cp -R node_modules/.vite/task-cache ../worktree/node_modules/.vite/
cd ../worktree
echo "== worktree: same commit, checkout's cache"
"$vt" run list-root

With vt built from 40cb9ca (macOS 27.2 arm64, Node 26.13.0):

== checkout: first run
$ node -e "console.log(require('fs').readdirSync('.').length)"
5

== checkout: second run
$ node -e "console.log(require('fs').readdirSync('.').length)" ◉ cache hit, replaying
5

---
vt run: cache hit, 412ms saved.
== worktree: same commit, checkout's cache
$ node -e "console.log(require('fs').readdirSync('.').length)" ○ cache miss: '.git' added in workspace root, executing
5

Cause

.git paths are already kept out of the fingerprint when a task reads them: tracked_accesses.rs skips every path under .git. A directory listing doesn't go through that filter. should_ignore_entry drops only ., .., .DS_Store and dist, so the root listing keeps .git with its DirEntryKind, Dir in a checkout and File in a worktree.

vite-plus 1.4.0 ships the same code (fingerprint.rs at a3c087a).

Proposed fix

Skip .git in directory listings the way .DS_Store and dist are skipped, which matches what tracked_accesses.rs already does for reads under .git. A PR that does this follows, with an e2e case where a task that lists the root records its entry with .git as a directory and replays it after .git becomes a file.

If you'd rather keep .git's presence in the listing, the alternative is to record .git without its kind, so a directory and a file compare equal. We went with dropping it because a read of .git itself is already dropped, so its presence doesn't count anywhere else.

The miss message

A changed kind is reported as added: determine_folder_change_kind returns InputChangeKind::Added when an entry's name matches and its kind differs. '.git' added in workspace root sent us looking for a new .git, when it had been there all along as a directory. A message such as '.git' changed from a directory to a file in workspace root would have pointed at the cause. That changes the output, so it isn't in the PR.

Related

#504 is about negative input patterns not reaching listing entries. A fix there would let a task exclude .git by configuration, but .git is never a task input, so it needs no configuration.