Processor-visible policy marker that constrains which actor and source categories may invoke named operations. Actor Policy turns actor/source attribution into enforceable workflow rules. It lets a document require direct principal action for sensitive operations such as authorization, capture, cancellation, consent, or contract amendment, while permitting delegated agents or API calls for lower-risk operations such as adding notes, requesting information, or preparing drafts. The policy is keyed by operation name. Each operation entry can constrain the actor category with `requiresActor`, require a source category with `requiresSource`, and/or reject a source category with `excludeSource`. The core actor categories are `principal`, `agent`, and `any`. The core source categories are `browserSession`, `apiCall`, and `documentRequest`. These are intentionally broad categories. Domain-specific policies may refine them by requiring a specialized actor or source type in the operation runtime, such as a strongly authenticated browser session or a provider-specific agent delegation. Actor Policy is a marker. It does not handle events, issue patches, or inspect timelines by itself. A supported operation channel/runtime reads it when evaluating an Operation Request or comparable event. If the event's actor or source does not satisfy the operation's policy, the operation is rejected or the scope terminates according to the hosting processor's rules. Timeline Providers are not responsible for enforcing this document policy; they provide infrastructure, attribution, append authorization, ordering, storage, and completeness guarantees. Blue documents use Actor Policy to decide how to interpret those attributed entries.