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Exclusive sibling branch expansion: Expansion change set omits closed branches · case 02

Expansion change set omits closed branches produces the wrong hierarchical widget state in a regression fixture.

Member previewVariant 2 · 3 implementations · 7 checks per implementation

Case contract

Expanding a branch in exclusive mode closes its sibling branches and their descendants, but leaves ancestor and unrelated branch expansion intact. Expansion of disabled or leaf nodes is ignored. Focus within a newly closed sibling moves to that sibling root. Manual expansion survives later mode-off operation. Report whether pre-operation focus was a terminal row as provenance.

Why this case matters

Offline executable model of a hierarchical accessibility interaction; inputs are bounded and valid as stipulated. No browser, assistive technology, or normative ARIA conformance is claimed.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
close sibling	`[["a", "q", "r"], "b", ["a", "q", "r"], {"a": true, "b": false, "bb": false, "q": true, "r": true}, true]`	`[["a", "q", "r"], "b", ["a", "b", "bb"], {"a": true, "b": false, "bb": false, "q": true, "r": true}, true]`	Failed

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

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