FA-4570 / Iterator consumption / Member archive

Groupby adjacency not global key · case 05

The operation returns a result or retained state that violates this contract: Group consecutive equal values into [key,group] pairs; separated equal runs remain separate.

Member previewVariant 5 · 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
separate equal runs	`[["a", ["a", "a"]], ["b", ["b"]]]`	`[["a", ["a"]], ["b", ["b"]], ["a", ["a"]]]`	Failed

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This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

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