freeze · garrytan — Claude Code skill: what it does, how to install

---
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 -c "exec bash \"$HOME/.claude/skills/gstack/freeze/bin/check-freeze.sh\""'
          statusMessage: "Checking freeze boundary..."
    - matcher: "Write"
      hooks:
        - type: command
          command: 'bash -c "exec bash \"$HOME/.claude/skills/gstack/freeze/bin/check-freeze.sh\""'
          statusMessage: "Checking freeze boundary..."
    - matcher: "NotebookEdit"
      hooks:
        - type: command
          command: 'bash -c "exec bash \"$HOME/.claude/skills/gstack/freeze/bin/check-freeze.sh\""'
          statusMessage: "Checking freeze boundary..."
---
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# /freeze — Restrict Edits to a Directory

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

```bash
GSTACK_STATE_ROOT=$(~/.claude/skills/gstack/bin/gstack-paths --get GSTACK_STATE_ROOT); : "${GSTACK_STATE_ROOT:?gstack-paths failed; reinstall with ./setup or /gstack-upgrade}"
mkdir -p "$GSTACK_STATE_ROOT"/analytics
echo '{"skill":"freeze","ts":"'$(date -u +%Y-%m-%dT%H:%M:%SZ)'","repo":"'$(basename "$(git rev-parse --show-toplevel 2>/dev/null)" 2>/dev/null || echo "unknown")'"}'  >> "$GSTACK_STATE_ROOT"/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:

Set the user-selected boundary with the shared state writer. It resolves the physical absolute path and serializes replacement with investigation cleanup:
```bash
bash "$HOME/.claude/skills/gstack/freeze/bin/freeze-state.sh" set "<user-provided-path>"
```

Only report success if the helper succeeds. On `FREEZE_BUSY` or unexpected state, preserve it and ask the user to inspect recovery after any active writer finishes; never write or delete the state file directly.

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

## How it works

The hook reads `file_path` from the Edit/Write tool input JSON, or
`notebook_path` from a NotebookEdit (Jupyter notebook) call (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 neither path field (a non-file tool) is allowed. A deny names the
tool, the path field, the boundary and `/unfreeze`. 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 until explicitly removed via the state file. The hook
script reads it on every Edit/Write/NotebookEdit invocation. Boundaries containing spaces
are supported.

## Notes

- The trailing `/` on the freeze directory prevents `/src` from matching `/src-old`
- Freeze applies to Edit, Write and NotebookEdit only — Read, Bash, PowerShell, Glob, Grep are unaffected
- This prevents accidental edits, not a security boundary — Bash or PowerShell commands like `sed` or `Set-Content` can still modify files outside the boundary
- To deactivate, run `/unfreeze`; ending or killing a conversation does not remove persisted state