fix: honor compaction cancellation and replay identity

crates/worker/src/worker.rs

@@ -5291,6 +5291,10 @@ impl<C: LlmClient + 'static, St: Store> Worker<C, St> {
                 info!(new_segment_id = %new_segment_id, "Manual compaction succeeded");
                 Ok(ManualCompactResult::Compacted { new_segment_id })
             }
+            Err(WorkerError::CompactCancelled) => {
+                info!("Manual compaction was cancelled");
+                Err(WorkerError::CompactCancelled)
+            }
             Err(e) => {
                 warn!(error = %e, "Manual compaction failed");
                 self.alert(

crates/worker/tests/compact_events_test.rs

@@ -1736,7 +1736,11 @@ async fn manual_compact_cancel_clears_progress_before_returning_idle() {
             Event::CompactionProgress { compaction: None } => {
                 saw_interrupted = true;
             }
-            Event::Error { .. } => saw_cancel_error = true,
+            Event::Error { .. }
+            | Event::Alert(protocol::Alert {
+                level: protocol::AlertLevel::Error,
+                ..
+            }) => saw_cancel_error = true,
             Event::WorkerState { snapshot }
                 if snapshot.catalog_status() == protocol::WorkerStatus::Idle =>
             {