FA-39123 / Tree accessibility / Member archive

Virtual tree active-descendant lease: Virtual focus scrolls to wrong index or scrolls mounted rows · case 03

Virtual focus scrolls to wrong index or scrolls mounted rows produces the wrong hierarchical widget state in a regression fixture.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

A virtualized active row keeps its identity while offscreen. Expose an active descendant only after a matching mount generation acknowledges the row; scrolling requests mount without changing selection. A recycled slot must not satisfy an old lease. Collapse repairs the logical active row to the closest visible ancestor before mounting.

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
offscreen	`["b", null, "b", 0, ["a"], ["b", 3], []]`	`["b", null, "b", 2, ["a"], ["b", 3], []]`	Failed

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

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