feat: processed-event ledger, idempotent dispatch

crates/bootstrap/tests/bootstrap_test.rs

@@ -107,3 +107,34 @@ async fn server_publishes_to_the_outbox_even_when_bus_is_nats() {
     .unwrap();
     assert_eq!(queued, 1);
 }
+
+/// Handler names key the processed-event ledger, so each must be unique. The
+/// check runs over the real wiring, in both federation builds.
+#[tokio::test]
+async fn handler_names_are_unique() {
+    let pool = support::memory_pool().await;
+    let worker = bootstrap::build_worker_on(&support::test_config(), pool)
+        .await
+        .expect("worker builds");
+
+    let names = worker.handler_names();
+    let unique: std::collections::HashSet<_> = names.iter().collect();
+    assert_eq!(
+        unique.len(),
+        names.len(),
+        "duplicate handler name in {names:?}"
+    );
+    for core in [
+        "poster_sync",
+        "image_cleanup",
+        "search_cleanup",
+        "search_reindex",
+    ] {
+        assert!(names.contains(&core), "{core} missing from {names:?}");
+    }
+    assert_eq!(
+        names.contains(&"activitypub"),
+        cfg!(feature = "federation"),
+        "{names:?}"
+    );
+}