The guards report an invariant break instead of computing around it, and no
data reaches them, so they are called directly: coverage 97.4% -> 97.7%,
which also covers the empty-cover skip through a literal operand.
operandDraw's doc keeps why neither wider set works, since both were tried
here — containment reaches a sibling the operand never renders, the render
closure reaches a source two operands share — and drops the rest.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
A builtin could be spelled as prep (args parsed once, at compile) or call
(args parsed per render), reaching the same closure by two routes. Nothing
enforced the "exactly one of" invariant: supplying both silently dropped
call, supplying neither compiled and then panicked inside a render, and a
test existed only to police it.
prep does everything call did, so it is now the one spelling. The zero-arg
shapes the README already names — a derivation reads the output emitted so
far, a generator reads only the rng — lift through derive and generate, so
the registry reads as that taxonomy. iban stops looking its country up per
render.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>