Anti-Entropy: The Background Sweep That Compares Whole Replicas, Not Single Reads

Subtitle: Swap the roots first - pay only for the difference. Panel one - The gap only it fills: - Read repair: read path only - Hinted handoff: hints expire - Neither touches cold keys - Only repair for data nobody reads Panel two - The Merkle trick: - Hash key ranges into leaves, to a root - Swap roots first: match means zero bytes - Mismatch: walk only differing subtrees - Cost tracks divergence, not dataset Panel three - Three safe readings that lie: - Non-blocking: clients pass, disk does not - Floor is the tombstone TTL, not a dial - LWW can pin the clock-skew winner Panel four - Falsify it: - Stop a replica, write a cold key - Restart, read at CL one pinned to it - No sweep: stale value stays forever - Cycle past the grace window: rows return