Daylight Saving Time Edge Cases

When clocks spring forward, one local hour does not exist. When they fall back, the same local time happens twice. Calendar bugs love DST week.

Mitigations

• Use IANA zone IDs (e.g. America/New_York) instead of fixed offsets.
• For recurring events, store the next occurrence as an instant, not only wall time.

Our Timezone Converter reflects IANA rules for historical and future transitions where data exists.