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Observed-remove set with unique tags: add tags collide across replicas · case 05

Removing an element at one replica also cancels a concurrent add of the same element elsewhere.

Member previewVariant 5 · 3 implementations · 8 checks per implementation

Case contract

Each add at replica r creates tag "r:k" where k is r's add counter. A remove at r tombstones only the tags of that element r currently observes and removes them locally. ["merge", s, d] unions tombstones and live tags into d, then subtracts d's tombstones and drops elements with no live tags. Return sorted members per replica.

Why this case matters

Observed-remove sets give add-wins semantics for concurrent add/remove pairs.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
same counters on different replicas do not collide	`[[], []]`	`[["x"], ["x"]]`	Failed

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