Struct ErasureCascadeObserver 

pub struct ErasureCascadeObserver { /* private fields */ }

L2 observer that drives the E-user-3 cascade. On every UserErasureScheduled event it:

1. Looks up the user’s encrypted-PII rows via the attached PiiRowStore.
2. Calls PiiRowStore::tombstone to mark every row soft-deleted.
3. Invokes the attached DekShredder to drop the underlying DEK.
4. Records an ErasureCompletion the caller can convert into a UserErasureCompleted event on the next tick.

The observer holds its own cursor — the router still centralises dedup + gap detection via the Projection trait.

Implementations

impl ErasureCascadeObserver

pub fn new(rows: Box<dyn PiiRowStore>, shredder: Box<dyn DekShredder>) -> Self

Construct the observer with concrete backends.

pub fn drain_completions(&mut self) -> Vec<ErasureCompletion>

Drain accumulated ErasureCompletions. The caller feeds each one back into an ActionContext::emit_event(UserErasureCompleted { ... }) so the next WAL tick anchors the receipt.

pub fn pii_rows(&self) -> &dyn PiiRowStore

Borrow the store for inspection — tests only.

pub fn shredder(&self) -> &dyn DekShredder

Borrow the shredder for inspection — tests only.

pub fn into_completed_event( completion: &ErasureCompletion, schema_version: u16, transparency_log_index: u64, ) -> UserErasureCompleted

Convenience — build a UserErasureCompleted event from a drained completion. The caller chooses the schema_version / transparency log index from its own anchor; this helper wires the remaining five fields.

pub fn per_region_events( completion: &ErasureCompletion, schema_version: u16, ) -> Vec<PerRegionErasureProgress>

Convenience — fan out a completion’s per-region progress entries as PerRegionErasureProgress events (two-phase commit). Single-region backends emit one event; multi- region backends emit one event per participating region. The caller emits these before the terminal UserErasureCompleted receipt so external consumers see the full erasure transcript.

Trait Implementations

impl Projection for ErasureCascadeObserver

fn observes(&self) -> &[TypeCode]

TypeCodes this projection observes — the router filters incoming events against this slice.

fn on_event( &mut self, event: &EventRecord, ctx: &ProjectionContext<'_>, ) -> Result<(), ProjectionError>

Apply an event. Called only after router-side dedup + gap checks have succeeded. Implementations must:

fn on_state_change( &mut self, _new_state: ObserverState, ) -> Result<(), ProjectionError>

React to a worker-state transition (Passive ↔ Active ↔ Draining). Default is no-op.

fn last_applied(&self) -> Option<(u64, Tick)>

Last (sequence, tick) applied — None if the projection is fresh.