_delay_seconds subtracted two aware datetimes sharing the household
ZoneInfo, which Python does as wall-clock arithmetic, so the sweep fired
an hour late at spring-forward and an hour early at fall-back. Both
instants are now compared and subtracted in UTC.
A nonexistent rollover time resolves to the first valid wall minute
at/after it (the gap's end); an ambiguous one resolves to its first
occurrence (fold=0). Adds America/New_York spring-forward, fall-back,
nonexistent and ambiguous cases alongside the ordinary EDT case.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
overseerandClaude Opus 5.5
dev_agent