Cancel a subscriber operation

Requires subscribers:read. Tagging and cancelling a tagging task also require subscribers:tag; creating tag definitions requires tags:write; triggering automations requires automations:trigger. Personal keys retain current company role restrictions. Company keys retain company-scoped authority. Workers recheck authority on every page. Cancellation stops future pages and keeps applied tags. An action already in flight may finish; its contact is reported as uncertain. Terminal cancellation is idempotent.