FA-82619 / Chess move legality / Member archive

Rook reaching the eighth rank asked for a promotion · case 04

"a1a8" for a rook returns "promotion required".

Member previewVariant 4 · 3 implementations · 8 checks per implementation

Case contract

Input: {"board", "uci": move string}. Return "ok" or a reason: "syntax" (length not 4-5, squares outside a1-h8, or from equals to), "no piece" (origin empty), "promotion required" (a white pawn reaching rank 8 or black pawn reaching rank 1 without a suffix), "unexpected promotion" (suffix on any other move), "bad promotion" (suffix not one of q, r, b, n).

Why this case matters

Engines and servers exchange moves in this long algebraic format.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
rook reaches last rank	`"promotion required"`	`"ok"`	Failed

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