knownSignInSource compared a trusted device's expiry with new Date()
while the throttle around it times its waits with Date.now(). The test
mocks Date.now() only, so it set the device to expire 30 days after its
fixed clock, which the real date passed on 2026-10-26 at noon UTC; from
then on the remembered browser read as expired and the test failed on
every run. One clock decides both now, and the test's expiry is fixed
against it. A further case pins that an expired device gets no
exemption.
Marc-André Bombeck
b180d09fae