FA-47209 / Bounded deques / Member archive

Deque rollback normalizes the saved physical head to zero · case 04

Deque rollback normalizes the saved physical head to zero.

Member previewVariant 4 · 3 implementations · 6 checks per implementation

Case contract

Undo a failed bounded ring mutation from a before-image journal. Replay writes newest-first, restore captured head/size/epoch, release reserved capacity, reclaim newly allocated blocks newest-first and consume the journal.

Why this case matters

Controlled bounded deque implementation model with explicit storage and lifecycle observations.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
0	`[[4, null], 0, 1, 3, 0, [5, 4], []]`	`[[4, null], 1, 1, 3, 0, [5, 4], []]`	Failed

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