keystone-check-drift

name	keystone-check-drift
description	Run the drift sensor on the current diff — fast pre-verify check that loaded charter rules still match what the code is doing.
tools	["Read","Bash","Grep","Glob"]
model	sonnet

keystone:check-drift — fast pre-verify drift check

Compares the in-progress diff against loaded charter rules. Fires before the full computational sensor suite — catches the obvious case where the agent is implementing something the rules explicitly disallow.

Canonical playbook: .charter/actions/check-drift.md. Sensor contract at .charter/sensors/drift.md. Full discipline at .charter/guides/process/implementation.md.

Run

Open .charter/actions/check-drift.md and execute every activity.

When to trigger

• Mid-implementation, before running /keystone:verify.
• After a large refactor that touched many regions — make sure the loaded idiom rules still apply.
• When /keystone:verify keeps failing on the same rule — drift is often the upstream cause.