Sweep follow-up to #2641's lib/fs-utils.ts helper: bun on Windows throws EEXIST from a recursive mkdir on an existing dir, so every unguarded recursive mkdirSync on a Windows-reachable path is a latent crash. Converted: bin/gstack-decision-log (unguarded, runs on every decision log — the second call on any machine hits the pre-existing projects dir), bin/gstack-evidence logsDir + ledger dir sites, and bin/gstack-redact-prepush's skip-log site (already try-wrapped, so its failure mode was a silent skip-log loss rather than a crash — the fix makes the log survive). The ~15 remaining gbrain/mac-lane sites are deliberately left alone.
Regression: fs-utils.test.ts drives gstack-decision-log twice, the second run under the bun-Windows EEXIST preload fixture — the pre-sweep code exits 1 with EEXIST there; verified red against v1.68.3.0.
fs.mkdirSync(dir, { recursive: true }) is a no-op on an existing directory
in Node, but bun on Windows throws EEXIST - crashing hook install on any
repo whose .git/hooks already existed, leaving the repo unprotected.
Add lib/fs-utils.ts mkdirpSync: swallow EEXIST only when statSync confirms
the path is an existing directory; a regular file occupying the path, a
stat failure, or any other errno still rethrows. Use it in
installPrepushHook().
The regression test emulates the Windows bun fs semantics via a
bun --preload fixture, so the exact crash path runs (and fails on the old
code) on any platform, including CI Linux.
Absorbed from PR #2641 with authorship preserved.
Fixes#2635
Garry Tan