FA-8389 / Tree accessibility / Member archive

Tree keyboard expansion: Right-arrow on an expanded parent focuses its last child · case 04

Right-arrow on an expanded parent focuses its last child.

Member previewVariant 4 · 3 implementations · 11 checks per implementation

Case contract

Right expands then enters the first child; Left collapses only the current branch or focuses its parent; roots retain focus; collapse-all clears every expansion.

Why this case matters

A deterministic model of tree keyboard expansion; this isolates one interface invariant without requiring a browser.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
descend	`["c", ["a"]]`	`["b", ["a"]]`	Failed

MEMBER ARCHIVE

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

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