FA-110 / Distributed coordination / Member archive

Out-of-order delivery permanently loses a dependent update · case 05

A message whose prerequisites arrive later is dropped or never revisited after another pending message becomes ready.

Member previewVariant 5 · 3 implementations · 7 checks per implementation

Case contract

Initial IDs are already applied. Deliveries are [ID,dependency IDs], with duplicate IDs denoting the same operation. Apply an ID only after all dependencies are applied. Return sorted applied and pending IDs after exhausting all currently satisfiable dependencies; missing dependencies and cycles remain pending. Payload conflict resolution is outside this model.

Why this case matters

Models causal message admission over reordered delivery, including transitive unlocks, replayed deliveries and permanently unavailable prerequisites.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
reverse dependency chain	`[["op-0"], []]`	`[["op-0", "op-1", "op-2", "op-3", "op-4", "op-5", "op-6", "op-7"], []]`	Failed

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