FA-1464 / Concurrency / Member archive

Commit a two-phase transaction: Commit messages precede the durable coordinator decision · case 04

The distributed transaction operation is admitted even though commit messages precede the durable coordinator decision.

Member previewVariant 4 · 3 implementations · 9 checks per implementation

Case contract

Return a Boolean admission decision for commit a two-phase transaction. The record r must satisfy all of: all(x == 'prepared' for x in r['all_prepared']); 'abort' not in r['no_abort_vote']; r['decision_durable'] is True; set(r['participant_set'][0]) == set(r['participant_set'][1]); r['coordinator_epoch'][0] == r['coordinator_epoch'][1]. Extra tracing fields are ignored; validation does not mutate the record.

Why this case matters

A deterministic local contract for concurrency. Each negative fixture violates exactly one invariant. No transport timing, persistence, cryptographic verification, or full protocol implementation is claimed.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
Commit messages precede the durable coordinator decision	`true`	`false`	Failed

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