v0.6.4: try_lock in the periodic reorder-buffer flush task Fourth same-night fix in the lock-contention investigation. reorder_flush ticks every 10ms and was unconditionally blocking on the same lock handle_incoming needs on every incoming Data packet, even though its own work is almost always redundant under real load (handle_incoming's inline drain already does it). Switched to try_lock -- skip the tick when contended, worst case a truly idle straggler waits one extra ~10ms before its own staleness timeout flushes it.