FA-82757 / Chess move legality / Member archive

Black rights looked up on rank 1 · case 02

Black file letters never map to rooks on rank 8.

Member previewVariant 2 · 3 implementations · 8 checks per implementation

Case contract

Input: {"board", "rights"}: rights letters are K/Q (outermost own rook on the back rank on the king's h-side / a-side), file letters A-H or a-h (the own rook on that file), or "-". A right only counts if the king is on its back rank (rank 1 for white, 8 for black) and the rook exists. Return the sorted distinct list of rook squares that carry castling rights.

Why this case matters

Chess960 and X-FEN positions encode castling by rook file; a wrong mapping castles with the wrong rook.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
standard KQkq	`["a1", "h1"]`	`["a1", "a8", "h1", "h8"]`	Failed

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