FA-47149 / Bounded deques / Member archive

Deque shrink reallocates while a storage borrow exists · case 04

Deque shrink reallocates while a storage borrow exists.

Member previewVariant 4 · 3 implementations · 8 checks per implementation

Case contract

A bounded deque shrinks by half, floored by live size and a minimum allocation, only at or below low occupancy, with no borrows and with resulting capacity at least the configured high watermark. Unchanged allocations keep epoch.

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
3	`[8, true, 5, 5, 4, 7, 1]`	`[16, false, 4, 13, 4, 7, 1]`	Failed

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