you can trim a couple more off the $m assignment to:

$_="1 2 3\n4 5 6\n7 8 9\n";$m="XO"x5;
{print;<>=~/^\d$/until$&&&s/$&/$p=chop$m/e;
/^($p.){3}|($p.{5}){2}$p|^.(...$p){3}|($p{7}){2}$p/ms||$m&&redo}
y/0-9/-/,print
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I am still trying to grok a way to trim that regex down. a definite ++