FA-54205 / Accessibility interaction semantics / Member archive

Negative braille pan offsets index from the document end · case 05

Negative braille pan offsets index from the document end.

Member previewVariant 5 · 3 implementations · 8 checks per implementation

Case contract

Input [cells,offset,width,route] where cells [source_start,source_end,content,editable]. Clip display window by nonnegative offset and width. Each cell has one display position regardless of content length. Routing uses a zero-based position inside displayed cells; return None if outside window or cell not editable, otherwise [source_start,source_end]. Display contents replace empty cell content with a space; protected content (exact token SECRET) displays a bullet. Return [display,source_ranges,route_result,has_previous,has_next]. Source ranges preserve zero-width insertion cells.

Why this case matters

Offline accessibility bridge model with explicit policy; useful for testing semantic API adapters independently of browser implementations.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
contract fixture 7	`[[], [], null, false, true]`	`[["a"], [[0, 1]], [0, 1], false, true]`	Failed

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

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