Struct PhasePreparation 

pub struct PhasePreparation {
    pub name: String,
    pub produces: Vec<String>,
    pub run: Arc<dyn Fn(State, Arc<dyn SessionWriter>) -> Pin<Box<dyn Future<Output = ()> + Send>> + Send + Sync>,
}

A preparation effect that can materialize state before a phase is entered.

Preparations run after an outbound transition guard selects a target phase but before the machine commits to entering that target. They are intended for authoritative preconditions such as loading records, retrieving catalog facts, fetching policy, or hydrating state from durable storage.

Fields

name: String

Stable name for diagnostics.

produces: Vec<String>

State keys this preparation is expected to produce.

run: Arc<dyn Fn(State, Arc<dyn SessionWriter>) -> Pin<Box<dyn Future<Output = ()> + Send>> + Send + Sync>

Async effect that can mutate state and/or write context.