Per Brian: never invent. Unknown suit -> 'x' (e.g. "Ax","Kx","4x"); fully
unknown card -> "x". "AA, ace of spades" -> ["As","Ax"]; "AK on A4x" -> board
["Ax","4x","x"]. Each card's suit is independent (a hole 'As' doesn't make a
board ace 'As'). Viewer renders 'x' as a muted unknown card and 'Rx' as the rank
with a neutral suit dot.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>