FA-46009 / Bounded deques / Member archive

Block lookup omits the final valid successor · case 04

Block lookup omits the final valid successor.

Member previewVariant 4 · 3 implementations · 6 checks per implementation

Case contract

For nonempty, variable-size deque blocks, resolve a logical index into [block index, local offset, value, total size, predecessor value, successor value]. Null neighbors mark sequence endpoints. Directory is built from cumulative block lengths.

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
third block head	`[2, 0, 7, 5, 6, null]`	`[2, 0, 7, 5, 6, 8]`	Failed

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