Serialize startup prepared artifact reclamation

crates/lazaret-prepared-lower/tests/prepared_lower/publication.rs

@@ -449,6 +449,60 @@ fn selected_gc_is_idempotent_only_at_the_durable_reclaim_boundary() {
     assert!(fixture.store.gc_artifacts(&[id]).is_err());
 }
 
+#[test]
+fn concurrent_unleased_gc_serializes_observation_with_reclaim() {
+    let fixture = Fixture::new();
+    let artifact = fixture
+        .store
+        .prepare(&fixture.request(
+            75,
+            &[(
+                layer(&[Entry {
+                    path: "payload",
+                    kind: EntryType::Regular,
+                    data: b"concurrent-gc",
+                    target: None,
+                    mode: 0o644,
+                }]),
+                OCI_TAR,
+            )],
+        ))
+        .unwrap();
+    let (_, first) = fixture.independent_store();
+    let (_, second) = fixture.independent_store();
+    let barrier = Arc::new(Barrier::new(3));
+    let first_barrier = Arc::clone(&barrier);
+    let first = thread::spawn(move || {
+        first_barrier.wait();
+        first.gc_unleased_artifacts()
+    });
+    let second_barrier = Arc::clone(&barrier);
+    let second = thread::spawn(move || {
+        second_barrier.wait();
+        second.gc_unleased_artifacts()
+    });
+
+    barrier.wait();
+    let results = [
+        first.join().unwrap().unwrap(),
+        second.join().unwrap().unwrap(),
+    ];
+    assert_eq!(results.iter().map(Vec::len).sum::<usize>(), 1);
+    assert_eq!(
+        results.iter().flatten().next().unwrap().outcome,
+        ReclaimOutcome::Removed
+    );
+    assert!(
+        fixture
+            .catalog
+            .snapshot()
+            .unwrap()
+            .prepared_artifacts
+            .is_empty()
+    );
+    assert!(!fixture.artifact_root(&artifact).exists());
+}
+
 #[test]
 fn selected_artifact_excludes_gc_until_the_claim_is_released() {
     let fixture = Fixture::new();