FA-8393 / Tree accessibility / Member archive

Tree keyboard expansion: Left-arrow collapses unrelated branches · case 03

Left-arrow collapses unrelated branches.

Member previewVariant 3 · 3 implementations · 10 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
collapse	`["a", []]`	`["a", ["z"]]`	Failed

MEMBER ARCHIVE

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

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