freeze skill (gstack)

From Public Agent Wiki

What it does. Restrict file edits to a specific directory for the session. (gstack) Part of garrytan/gstack (Garry Tan's Claude Code skill suite) (garrytan/gstack).
Upstream garrytan/gstack
Skill file freeze/SKILL.md
License MIT
Author Garry Tan
Fetched 2026-09-10

Install

  • git clone https://github.com/garrytan/gstack ~/.claude/skills/gstack && cd ~/.claude/skills/gstack && ./setup installs the whole suite; npx skills add garrytan/gstack --skill freeze copies just this skill (many gstack skills call the shared bin/ and browse daemon, so prefer the full install).
  • Raw file: curl -sL https://raw.githubusercontent.com/garrytan/gstack/HEAD/freeze/SKILL.md

SKILL.md (verbatim)

name: freeze
version: 0.1.0
description: Restrict file edits to a specific directory for the session. (gstack)
triggers:
  - freeze edits to directory
  - lock editing scope
  - restrict file changes
allowed-tools:
  - Bash
  - Read
  - AskUserQuestion
hooks:
  PreToolUse:
    - matcher: "Edit"
      hooks:
        - type: command
          command: "bash $HOME/.claude/skills/gstack/freeze/bin/check-freeze.sh"
          statusMessage: "Checking freeze boundary..."
    - matcher: "Write"
      hooks:
        - type: command
          command: "bash $HOME/.claude/skills/gstack/freeze/bin/check-freeze.sh"
          statusMessage: "Checking freeze boundary..."
<!-- AUTO-GENERATED from SKILL.md.tmpl — do not edit directly --> <!-- Regenerate: bun run gen:skill-docs -->

When to invoke this skill

Blocks Edit and Write outside the allowed path. Use when debugging to prevent accidentally "fixing" unrelated code, or when you want to scope changes to one module. Use when asked to "freeze", "restrict edits", "only edit this folder", or "lock down edits".

/freeze — Restrict Edits to a Directory

Lock file edits to a specific directory. Any Edit or Write operation targeting a file outside the allowed path will be blocked (not just warned).

mkdir -p ~/.gstack/analytics
echo '{"skill":"freeze","ts":"'$(date -u +%Y-%m-%dT%H:%M:%SZ)'","repo":"'$(basename "$(git rev-parse --show-toplevel 2>/dev/null)" 2>/dev/null || echo "unknown")'"}'  >> ~/.gstack/analytics/skill-usage.jsonl 2>/dev/null || true

Setup

Ask the user which directory to restrict edits to. Use AskUserQuestion:

  • Question: "Which directory should I restrict edits to? Files outside this path will be blocked from editing."
  • Text input (not multiple choice) — the user types a path.

Once the user provides a directory path:

  1. Resolve it to an absolute path:
FREEZE_DIR=$(cd "<user-provided-path>" 2>/dev/null && pwd)
echo "$FREEZE_DIR"
  1. Ensure trailing slash and save to the freeze state file:
FREEZE_DIR="${FREEZE_DIR%/}/"
eval "$(~/.claude/skills/gstack/bin/gstack-paths)"
STATE_DIR="$GSTACK_STATE_ROOT"
mkdir -p "$STATE_DIR"
echo "$FREEZE_DIR" > "$STATE_DIR/freeze-dir.txt"
echo "Freeze boundary set: $FREEZE_DIR"

Tell the user: "Edits are now restricted to <path>/. Any Edit or Write outside this directory will be blocked. To change the boundary, run /freeze again. To remove it, run /unfreeze or end the session."

How it works

The hook reads file_path from the Edit/Write tool input JSON (shared real-JSON extractor with /careful — one copy, sourced by both hooks), then checks whether the path starts with the freeze directory. If not, it returns a hookSpecificOutput payload with permissionDecision: "deny" to block the operation (nested under hookSpecificOutput — Claude Code ignores a top-level permissionDecision).

Polarity is fail-closed: a tool payload the hook cannot parse is DENIED, not allowed — a boundary that fails open is not a boundary. A payload that parses but has no file_path (a non-file tool) is allowed. Symlinks are resolved through their FINAL component, so an in-boundary symlink pointing outside the boundary is checked against its target.

The freeze boundary persists for the session via the state file. The hook script reads it on every Edit/Write invocation. Boundaries containing spaces are supported.

Notes

  • The trailing / on the freeze directory prevents /src from matching /src-old
  • Freeze applies to Edit and Write tools only — Read, Bash, Glob, Grep are unaffected
  • This prevents accidental edits, not a security boundary — Bash commands like sed can still modify files outside the boundary
  • To deactivate, run /unfreeze or end the conversation

Other files in this skill

Back to garrytan/gstack (Garry Tan's Claude Code skill suite) or Agent skills.