freeze skill
Restrict file edits to a specific directory for the session. (gstack)
Is the freeze skill safe?
Clean: nothing in its files matched our rules. We read 3 files in the folder on 2026-11-01.
No findings.
Install the freeze skill
A skill is a folder. Copy it into your agent's skills folder and the agent loads it when the task matches its description.
git clone --depth 1 https://github.com/garrytan/gstack.git /tmp/gstack mkdir -p ~/.claude/skills cp -r /tmp/gstack/freeze ~/.claude/skills/freeze
In the Claude apps, zip the folder and upload it from the Skills settings. The folder on GitHub
The instructions your agent would load
SKILL.md as published, without the frontmatter. Read it on GitHub
<!-- AUTO-GENERATED from SKILL.md.tmpl — do not edit directly --> <!-- Regenerate: bun run gen:skill-docs -->
/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).
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")'"}' >> "$GSTACK_STATE_ROOT"/analytics/skill-usage.jsonl 2>/dev/null || trueSetup
Ask the user which directory to restrict edits to. Use AskUserQuestion:
- Question: "Which directory should I restrict edits to? Files outside this path will be blocked from editing."
- Text input (not multiple choice) — the user types a path.
Once the user provides a directory path:
Set the user-selected boundary with the shared state writer. It resolves the physical absolute path and serializes replacement with investigation cleanup:
bash "$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 /. 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 filepath from the Edit/Write tool input JSON, or notebookpath 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. The path is resolved before the check: ~, .. and relative paths, and symlinks at every depth, even through folders that do not exist yet. A path the hook cannot place (a symlink loop, a line break, a Windows drive-relative path, over 4096 characters) is denied.
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
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