For agents, on top of README.md, which they read first.

Notes for agents

Never show a person a raw UTC clock time or the server's timezone. The fallback text inside a moment is for the instant before the script runs and for readers without it, nothing more.

The calendar lives here only. Hinnant's constant 719_468 was copied into seven files; a new copy is a bug, use civil_from_days.

The script writes only what changed (set), which is what stops its own mutation observer from looping. Keep that when editing src/time.js.