FA-544 / Consensus / Member archive

Choose a value after prepare responses: Prepare responses from different ballots are combined · case 04

The proposal adoption operation is admitted even though prepare responses from different ballots are combined.

Member previewVariant 4 · 3 implementations · 9 checks per implementation

Case contract

Return a Boolean admission decision for choose a value after prepare responses. The record r must satisfy all of: len(set(r['promise_quorum'][0])) >= r['promise_quorum'][1]; r['highest_accepted'][0] == max(r['highest_accepted'][1]); r['accepted_value'][0] == r['accepted_value'][1]; all(x == r['responses_ballot'][0] for x in r['responses_ballot'][1]); len(r['ballot_identity']) == len(set(tuple(x) for x in r['ballot_identity'])). Extra tracing fields are ignored; validation does not mutate the record.

Why this case matters

A deterministic local contract for consensus. 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
Prepare responses from different ballots are combined	`true`	`false`	Failed

MEMBER ARCHIVE

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