FA-38942 / Tree accessibility / Member archive

Tree expansion undo journal: Undo applies a stale branch generation · case 02

Undo applies a stale branch generation produces the wrong hierarchical widget state in a regression fixture.

Member previewVariant 2 · 3 implementations · 6 checks per implementation

Case contract

Undo restores the prior expansion set only for surviving branches. Non-undoable loading and filter expansions remain separate. Journal entries belong to a tree generation; stale generations are discarded. Focus restored from journal must be visible under restored expansion.

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
stale latest	`[["a"], ["a", "q"], [{"after": ["a"], "before": ["r"], "focus": "r", "generation": 2}], [{"old": true}, {"after": [], "before": ["a"], "focus": "b", "generation": 1}], ["r", "q", "s"], "r"]`	`[["q"], ["a", "q"], [{"after": ["a"], "before": ["r"], "focus": "r", "generation": 2}], [{"old": true}], ["r", "q", "s"], "s"]`	Failed

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

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