I think id be inclined to not use /[a-z]/i, I personally think the below is easier to read.

my $fullname = qr/\A[[:alpha:]]{1,30}\z/;
my $username = qr/\A[[:alpha:]]\w{2,16}\z/;
[download]

TIMTOWTDI

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demerphq

_{<Elian> And I do take a kind of perverse pleasure in having an OO assembly language...}