diff --git a/.kiro/specs/raft-drive-async/tasks.md b/.kiro/specs/raft-drive-async/tasks.md
index 6926cbd7..b3803c0f 100644
--- a/.kiro/specs/raft-drive-async/tasks.md
+++ b/.kiro/specs/raft-drive-async/tasks.md
@@ -129,7 +129,7 @@ Tasks mirror the design's 4-phase migration. The slow lane is foundational (ever
   - _Requirements: 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7_
   - _Depends: 3.4_
 
-- [ ] 4.3 Thread-role compliance and heartbeat performance check
+- [x] 4.3 Thread-role compliance and heartbeat performance check
   - Verify no blocking operation runs inline on the iomgr loop or delaymgr timer for the in-scope paths; bounded blocking runs in the vtask pool only under the admission reservation and long blocking I/O only on the lane.
   - Measure steady-state heartbeat cadence at 3–5 controllers and confirm no added latency attributable to the new dispatch path.
   - Observable: a compliance assertion/inspection shows the drive threads non-blocking; heartbeat cadence matches the pre-change baseline.