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Reserve a queued message for delivery: A FIFO message overtakes an earlier group member · case 03

The queue reservation operation is admitted even though a fifo message overtakes an earlier group member.

Member previewVariant 3 · 3 implementations · 9 checks per implementation

Case contract

Return a Boolean admission decision for reserve a queued message for delivery. The record r must satisfy all of: r['visible_now'][0] >= r['visible_now'][1]; r['not_expired'][0] < r['not_expired'][1]; r['no_live_reservation'][0] is None or r['no_live_reservation'][1] >= r['no_live_reservation'][0]; r['consumer_credit'][0] < r['consumer_credit'][1]; r['group_head'][0] == min(r['group_head'][1]). Extra tracing fields are ignored; validation does not mutate the record.

Why this case matters

A deterministic local contract for queues. 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
A FIFO message overtakes an earlier group member	`true`	`false`	Failed

MEMBER ARCHIVE

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