FA-39694 / Tree accessibility / Member archive

Hierarchical branch command lock: Command lock lookup drops ancestor locks · case 04

Command lock lookup drops ancestor locks produces the wrong hierarchical widget state in a regression fixture.

Member previewVariant 4 · 3 implementations · 10 checks per implementation

Case contract

A pending subtree mutation locks that branch and descendants, but does not lock siblings. Read-only inspection remains available. New commands use nearest locking ancestor for reason attribution; completed operation tokens release only their owned locks and never a replacement lock.

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
nested lock	`[true, null, {}, []]`	`[false, "busy:b", {"b": "B", "q": "Q", "r": "R"}, ["r", "b", "c", "q", "s"]]`	Failed

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

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