NotePlan Mirror

NotePlan Mirror answers one question when looking at a calendar in Fantastical: did I take notes on this meeting? NotePlan links a note to a calendar event, but Fantastical has no way to show that. The tool runs in the background every ten minutes, finds every event that has a NotePlan note, and creates a twin event with the same title, start, and end on a private iCloud calendar named NotePlan. With Fantastical’s Combine Identical Events setting on, the twin merges into the real event and tints it a second color, and the twin’s URL is a noteplan:// link that opens the note.

Each run is idempotent. It parses the event links in the NotePlan notes folder, enumerates the real events in a rolling window (seven days back, one day forward by default), resolves each note to the live occurrence including the right instance of a recurring series, then creates missing twins, updates twins whose title or time drifted, and deletes twins whose note or event is gone. A run with nothing changed does nothing. A hard guard refuses to modify any event outside the mirror calendar, so Google and Exchange events are never touched and nothing goes out to attendees.

The binary is a Swift package wrapped in a minimal signed app bundle, because a bare command-line tool cannot get a Calendar permission grant when launched by launchd. Flags and a JSON config cover the notes root, calendar and source names, the window size, location matching, the calendar color, a dry-run mode, a parse-only mode, and a limit for testing the first merge. Pushover can send a notification on save errors only.