gstack-investigate: PreToolUse hook path breaks on standalone marketplace installs (/../freeze/bin/check-freeze.sh not found) #1647

Summary

When gstack-investigate is invoked, it registers a PreToolUse:Edit and PreToolUse:Write hook with this command:

bash ${CLAUDE_SKILL_DIR}/../freeze/bin/check-freeze.sh

This path assumes both gstack-investigate and gstack-freeze are installed under a shared parent directory (monorepo-style, e.g. ~/.claude/skills/gstack/investigate/ and ~/.claude/skills/gstack/freeze/). But when installed as standalone marketplace skills, they land at:

• ~/.claude/skills/gstack-investigate/
• ~/.claude/skills/gstack-freeze/

So ${CLAUDE_SKILL_DIR}/../freeze/ resolves to ~/.claude/skills/freeze/ — which doesn't exist.

Error Observed

PreToolUse:Edit hook error
Failed with non-blocking status code: bash: /../freeze/bin/check-freeze.sh: No such file or directory

This fires on every Edit and Write operation for the duration of the session.

Impact

• ~150–800ms wasted per Edit/Write operation (bash tries to exec a nonexistent path)
• Noisy error shown in the UI on every file edit
• The scope lock feature silently fails — gstack-investigate's "debug scope boundary" never actually enforces anything on standalone installs

Root Cause Detail

The YAML frontmatter hook is registered unconditionally at skill invocation time:

hooks:
  PreToolUse:
    - matcher: "Edit"
      hooks:
        - type: command
          command: "bash ${CLAUDE_SKILL_DIR}/../freeze/bin/check-freeze.sh"
          statusMessage: "Checking debug scope boundary..."

The skill DOES have a safety check in the Scope Lock workflow section (line ~791):

[ -x "${CLAUDE_SKILL_DIR}/../freeze/bin/check-freeze.sh" ] && echo "FREEZE_AVAILABLE" || echo "FREEZE_UNAVAILABLE"

When FREEZE_UNAVAILABLE, it skips writing the freeze-dir state. But the YAML-level hooks are already registered and fire on every Edit regardless.

Reproduction

1. Install gstack-investigate and gstack-freeze as standalone marketplace skills (not from a bundled gstack install)
2. Invoke gstack-investigate in a session
3. Attempt any Edit or Write operation
4. Observe the /../freeze/bin/check-freeze.sh: No such file or directory error on every edit

Suggested Fixes

Option A — Correct the relative path for standalone installs:

bash ${CLAUDE_SKILL_DIR}/../gstack-freeze/bin/check-freeze.sh

Option B — Guard the hook command so it's a no-op when the script is missing:

bash -c '[ -x "${CLAUDE_SKILL_DIR}/../freeze/bin/check-freeze.sh" ] && bash "${CLAUDE_SKILL_DIR}/../freeze/bin/check-freeze.sh" || exit 0'

Option C — Gate hook registration on freeze availability (may not be possible in the current YAML hook format).

Environment

• Platform: Windows 11 / Claude Code
• gstack-investigate: standalone marketplace install at ~/.claude/skills/gstack-investigate/
• gstack-freeze: standalone marketplace install at ~/.claude/skills/gstack-freeze/
• Discovered via session transcript bfeeec6a-fd3e-4eb2-916b-5ec313989fe8 (RunPulse project)