FA-75189 / CRDT convergence / Member archive

LWW map with delete-wins ties: deletes drop the key instead of storing a tombstone · case 04

A stale put arriving by merge brings a deleted key back.

Member previewVariant 4 · 3 implementations · 9 checks per implementation

Case contract

Each key holds [value, ts, kind, writer] with kind 1 for a delete tombstone and 0 for a put. An incoming entry (local op or merge) replaces the stored one only if (ts, kind, writer) is lexicographically larger, so deletes win timestamp ties and writers break the rest. Tombstones are kept. ["merge", s, d] offers each of s's entries to d. Return sorted visible [key, value] pairs per replica.

Why this case matters

Document CRDTs built from per-field LWW registers must not let stale writes resurrect deleted fields.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
delete then stale put via merge stays deleted	`[[["k", "old"]], [["k", "old"]]]`	`[[], []]`	Failed

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