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Accessible subtree reparent transaction: Drop validation permits descendant cycles or protected parents · case 02

Drop validation permits descendant cycles or protected parents produces the wrong hierarchical widget state in a regression fixture.

Member previewVariant 2 · 3 implementations · 6 checks per implementation

Case contract

The closure contains a moved subtree and the source and destination are distinct parents. Reject drops into that closure or a read-only destination. Accepted moves replace the root parent, shift every descendant level by the parent-depth delta, invalidate sibling metadata, retain ID-based selection and focus, and increment only affected parent versions.

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
descendant target	`["c", {"b": 4, "c": 5, "outside": 0, "q": 3, "r": 0}, ["a", "z"], ["x", "b", "y"], ["c", "r"], {"outside": 8, "q": 7, "r": 4}, "c", ["c", "a"], ["c", "r"]]`	`["r", {"b": 1, "c": 2, "outside": 0, "q": 3, "r": 0}, ["a", "b", "z"], ["x", "y"], [], {"outside": 8, "q": 7, "r": 3}, "c", ["c", "a"], ["r"]]`	Failed

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

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