Zone Desk

Read a schedule written as a local wall clock and see the instants it actually produces. A recurring local time is not a recurring instant: 02:30 on 2026-03-08 in New York does not exist, and 01:30 on 2026-11-01 exists twice, an hour apart - so a job scheduled there does not run, or runs twice. And a time difference is not a number, it is a list of runs: New York to London is 5 hours for 337 days of 2026 and 4 hours for 28, in two separate windows, while across the equator New York to Sydney takes three distinct values. Adding 24 hours is not adding a day, the offset is often not a whole number of hours, and EST is a fixed -05:00 that never springs forward while CST is not. Five lanes over one schedule sheet: pick a time that survives the year, read what everyone's clock says, work out each difference as its runs, find the dates a job breaks, and decide what to change - plus a free browser-side engine that reads the full IANA database out of the runtime itself, with nothing fetched and nothing vendored. Derived from the dotnet-timezone skill in github/awesome-copilot (https://github.com/github/awesome-copilot). Not affiliated with or endorsed by GitHub or Microsoft.

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