Struct ProjectionReplayService 

pub struct ProjectionReplayService;

Projection replay service — fold/reducer model for custom aggregations.

Unlike ReplayService which assumes full snapshots, this service supports both full-snapshot and diff-based event logs. reducer.initial_state() returns the empty starting state, reducer.apply(state, event) accumulates each event.

Use for custom aggregations (transition count, cumulative metrics) or when the event log stores diffs rather than full snapshots.

Implementations

impl ProjectionReplayService

pub fn state_at_version<T>( events: &[VersionedTransitionEvent], flow_id: &str, target_version: u32, reducer: &dyn ProjectionReducer<T>, ) -> T