gstack-hook-check reports every TypeScript hook as "bun could not bundle" on Windows (Git Bash): MSYS argv path conversion breaks the built.tsv lookup #3100

Summary

On Windows with Git Bash, ./setup (v1.91.66.0+) exits 1 and refuses to register every TypeScript-backed
hook, with bun could not bundle the TypeScript entry. The hooks bundle fine. The failure is in
bin/gstack-hook-check's bookkeeping:

• It passes absolute POSIX paths (/c/Users/...) to bun.exe as argv.
• MSYS converts native-exe argv to Windows form (C:/Users/...).
• Bun.build therefore records rows keyed C:/Users/... in built.tsv.
• The later lookup searches for /c/Users/..., finds nothing, and treats a missing row as a bundle
  failure.

gstack-doctor shows the same false hooks: fail.

Environment

• gstack 1.91.68.0 (20eb620), global Claude install at ~/.claude/skills/gstack
• Windows 11 Pro, Git for Windows (Git Bash / MSYS2 runtime)
• Bun 1.4.2

Symptoms

./setup ends with exit 1:

gstack setup: refusing to register hooks that do not parse (Claude Code would block tool calls with them):
  .../hosts/claude/hooks/question-log-hook.ts:1: bun could not bundle the TypeScript entry
  .../hosts/claude/hooks/question-preference-hook.ts:1: bun could not bundle the TypeScript entry
  .../hosts/claude/hooks/auq-error-fallback-hook.ts:1: bun could not bundle the TypeScript entry
  .../hosts/claude/hooks/timeline-stop-hook.ts:1: bun could not bundle the TypeScript entry
  .../autoplan/bin/phase-publication-hook.ts:1: bun could not bundle the TypeScript entry
  .../plan-ceo-review/bin/mode-handoff-hook.ts:1: bun could not bundle the TypeScript entry
  Hooks that parse register as usual: bin/gstack-session-update careful/bin/check-careful.sh freeze/bin/check-freeze.sh

bin/gstack-doctor then reports fail hooks ... bun could not bundle the TypeScript entry.

The hooks are fine

The same entries bundle without error:

cd ~/.claude/skills/gstack/hosts/claude/hooks
bun build ./timeline-stop-hook.ts --target=bun --outdir "$(mktemp -d)"
# Bundled 4 modules in 11ms   (exit 0)

The check's own Bun.build call also succeeds. It is the argv spelling that changes:

E="$HOME/.claude/skills/gstack/hosts/claude/hooks/timeline-stop-hook.ts"   # /c/Users/.../timeline-stop-hook.ts
bun -e 'for (const e of process.argv.slice(1)) { const r = await Bun.build({ entrypoints: [e], target: "bun", packages: "external", metafile: true, throw: false }); console.log(`argv=${e} success=${r.success} inputs=${Object.keys(r.metafile?.inputs ?? {}).length}`) }' "$E"
# argv=C:/Users/.../timeline-stop-hook.ts success=true inputs=4

MSYS_NO_PATHCONV=1 bun -e 'console.log(process.argv[1])' "$E"
# /c/Users/.../timeline-stop-hook.ts

Root cause (bin/gstack-hook-check at 1.91.68.0)

1. Line 55 normalizes ROOT to POSIX form on Windows: ROOT=$(cygpath -u "$ROOT"), giving /c/Users/....
2. Lines 148-153 build ENTRIES as absolute paths under that POSIX ROOT:
   ENTRIES="$ENTRIES${shim%/*}/$entry$NL".
3. Line 156 onward runs "$BUN" -e '...' $ENTRIES > "$BUILT". bun.exe is a native Windows
   executable, so the MSYS runtime rewrites each /c/... argument to C:/.... The script prints
   ${entry}, the rewritten spelling, as column 1 of built.tsv.
4. Line 206 looks rows up by the POSIX spelling:
   result=$(awk -F '\t' -v e="$dir/$entry" '$1 == e' "$BUILT"). No row matches, so result is empty.
5. An empty result is reported as bun could not bundle the TypeScript entry (line ~208), even though
   the build succeeded.

So on Git Bash every TypeScript hook is rejected, whatever its content.

Suggested fixes (any one)

• Pass entries relative to ROOT. The script already does cd "$ROOT" before invoking bun, and MSYS
  does not rewrite relative paths. Key both the TSV and the lookup by the relative path.
• Normalize the lookup key on Windows: compare against cygpath -m "$dir/$entry" (or normalize both
  sides) in the awk lookup.
• Have the bun script echo the caller's spelling: pass entries via stdin or an env var (not
  converted by MSYS) instead of argv, and print exactly what it received.
• Distinguish "no row" from "build failed" in the message, e.g. no build result recorded for <entry>, so a bookkeeping miss isn't reported as a bundle error.

Impact

• ./setup exits 1 on every Windows Git Bash install from 1.91.66.0 onward, and gstack-doctor
  reports hooks: fail.
• Settings-level TypeScript hooks are not (re)registered. Previously registered fail-open hooks (the
  timeline-stop-hook Stop shim) keep working. Skill-frontmatter hooks that call their scripts by path
  (/autoplan, /plan-ceo-review) also keep working, since the scripts exist and build.
• Users following the message's advice ("repair the file ... half-applied edits") will find nothing
  to repair.