FA-82730 / Chess move legality / Member archive

Long castling puts the rook on the king's square · case 05

After e1c1 the rook is placed on c1 and then overwritten by the king.

Member previewVariant 5 · 3 implementations · 8 checks per implementation

Case contract

Input: {"board", "moves": [uci strings]}. Apply the moves in order and return the final board sorted by square. A king moving two files castles: the rook jumps from h to f (g-file destination) or from a to d (c-file destination). A pawn moving diagonally onto an empty square captures en passant, removing the pawn on the destination file and origin rank. A fifth character promotes to that piece in the mover's colour.

Why this case matters

Move application defines the position every later legality check sees.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
white long castle	`{"c1": "K", "e8": "k"}`	`{"c1": "K", "d1": "R", "e8": "k"}`	Failed

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