FA-82385 / Chess move legality / Member archive

Bishop never moves toward a1 · case 05

A bishop on f5 is not offered e4, d3 or the capture on c2, and some targets repeat.

Member previewVariant 5 · 3 implementations · 8 checks per implementation

Case contract

Input: {"board", "from": square of a rook, bishop or queen}. Return the sorted pseudo-legal destinations: walk each ray until the edge; an empty square is added, an enemy piece is added and ends the ray, a friendly piece ends the ray without being added.

Why this case matters

Move validators gate every move in engines, servers and arbiters; accepting an illegal move or rejecting a legal one corrupts the game record.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
bishop centre	`["c5", "e3", "e5", "e5", "f2", "f6", "f6", "g1"]`	`["c3", "c5", "e3", "e5", "f2", "f6", "g1"]`	Failed

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

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