A later catch-all stub silently makes an earlier specific stub unreachable #136

when(fn () => $r->find(1))->returns(new Book('one'));
when(fn () => $r->find(Arg::any()))->returns(null);
$r->find(1);   // null

"Most recently registered wins, earlier ones remain as fallbacks" is documented, and the README says to register the broad stub first — but the opposite order is not diagnosed: the specific stub stays registered, matches nothing, and even strictStubs does not report it, because unreachable is not the same as uncalled. The library's stated promise is that nothing happens silently.

Expected: registering a stub whose every position accepts anything (Arg::any(), unspelled, Arg::rest()) after another stub of the same method is refused with ConflictingExpectation, naming the specification it would shadow.

Found in the 2026-09-18 family review.