CACHE_DIR was the literal ".git/lmc-verify". In a linked worktree `.git` is a
FILE containing `gitdir: ...`, so `mkdir -p .git/lmc-verify` fails with "Not a
directory" -- and because the write is the last thing the script does, it failed
while the gate still printed green and exited 0. Every commit and push from a
worktree then re-swept API 33-36 for nothing, silently. That is the worst shape a
cache can fail in: invisible and expensive, and it was found by an agent paying
for it four times over rather than by the tool saying anything.
Measured both ways: in a worktree the old expression gives
`mkdir: cannot create directory '.git': Not a directory`, exit 1; `git rev-parse
--git-common-dir` gives the real path and exit 0.
--git-common-dir rather than --git-dir so the cache is SHARED between worktrees.
The key is the app/src tree hash, and identical content is identical content
whichever worktree produced it -- a sweep run in one is evidence for all of them.
The write also stops being silent. record_sweep() prints when it cannot record,
because a cache that never fills looks exactly like one that is working.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
JMR-devandClaude Opus 5
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