Strict Mode

React Strict Mode intentionally replays effect setup and cleanup in development. The adapter balances policy/group lifecycle operations under that behavior.

Registration ownership

Every registerPolicy call receives a private owner token and returns an idempotent cleanup function. A named policy remains available while at least one owner is mounted. Cleanup removes only its own token.

This handles:

• Strict Mode effect setup, cleanup, and setup replay.
• Multiple mounted forms using the same shared policy.
• Unmounting one form without unregistering another form's policy.
• Cleanup functions called more than once.

Provider engine stability

An internally created engine is stored in a ref and is stable across renders and Strict Mode effect replay. An injected engine is never destroyed by provider cleanup.

Dynamic policies

When a memoized policy array changes, React first releases the old registrations and then acquires the new ones. Keep the array stable for static policies to avoid unnecessary lifecycle work.

Subscriptions

Model subscriptions return a cleanup that removes only the current listener. useSyncExternalStore supplies the same revision getter for client and server snapshots.

Testing Strict Mode

Wrap a harness in <StrictMode> and assert that validation works once, errors are not duplicated, and the final unmount removes the policy. The package test suite includes this lifecycle case.