FA-4543 / Iterator consumption / Member archive

Takewhile consumes first failure · case 03

The operation returns a result or retained state that violates this contract: Consume the prefix before sentinel, consuming but excluding the first sentinel; return [prefix,remainder].

Member previewVariant 3 · 3 implementations · 4 checks per implementation

Case scope

A controlled failure with recorded boundary checks.

Why this case matters

A controlled local-runtime regression for collection APIs, language semantics, or ownership wrappers. Fixtures include boundary and interaction cases.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
middle stop	`[["a", "b"], []]`	`[["a"], ["b"]]`	Failed

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