feat: processed-event ledger, idempotent dispatch

crates/domain/src/testing/fakes/store.rs

@@ -64,6 +64,7 @@ pub struct InMemoryStore {
     pub(super) import_profiles: RwLock<HashMap<Uuid, ImportProfile>>,
     pub(super) follows: RwLock<Vec<(Uuid, SocialIdentity, FollowState)>>,
     pub(super) blocked: RwLock<Vec<(Uuid, SocialIdentity)>>,
+    pub(super) processed_events: RwLock<HashMap<(Uuid, String), chrono::NaiveDateTime>>,
 }
 
 impl InMemoryStore {
@@ -85,6 +86,7 @@ impl InMemoryStore {
             import_profiles: RwLock::default(),
             follows: RwLock::default(),
             blocked: RwLock::default(),
+            processed_events: RwLock::default(),
         })
     }
 
@@ -122,6 +124,23 @@ impl InMemoryStore {
         self.import_sessions.read().unwrap().len()
     }
 
+    pub fn processed_event_count(&self) -> usize {
+        self.processed_events.read().unwrap().len()
+    }
+
+    /// Inserts a ledger row with an explicit timestamp (for retention tests).
+    pub fn seed_processed_event(
+        &self,
+        id: &crate::events::EventId,
+        handler: &str,
+        processed_at: chrono::NaiveDateTime,
+    ) {
+        self.processed_events
+            .write()
+            .unwrap()
+            .insert((id.value(), handler.to_owned()), processed_at);
+    }
+
     pub fn refresh_session_count(&self) -> usize {
         self.refresh_sessions.read().unwrap().len()
     }