One event in, one Busy block in every other calendar
Caltsu reads each event, takes its start and end time, and writes a block at the same time in your other calendars. This page covers what happens when events change, repeat or disappear.
- Personalaino@gmail.comDentist, Dr. Salo08:30-09:15
- Client Aa.lehtinen@kestrel.comBusy08:30-09:15
- Client Baino@northwind.fiBusy08:30-09:15
When the source event changes
Caltsu keeps a record linking each event to the block it created, so every change lands on the same block.
| In the source calendar | In the other calendars | What Caltsu does |
|---|---|---|
| New eventDentist, Tue 08:30-09:15 | Busy08:30-09:15 | A block is created at the same time. |
| Time changedMoved to 10:00-10:45 | Busy10:00-10:45 | The existing block moves. No duplicate is created. |
| Title or notes editedRenamed to Dentist, follow-up | No visible change | The block keeps its title. Only times are copied. |
| Cancelled or deletedRemoved from the calendar | Block deleted | Caltsu deletes the block it created. |
| Block deleted by handSomeone removes the block in a client calendar | Busy10:00-10:45 | Caltsu recreates the block on the next sync, as long as the source event exists. |
Recurring events
Caltsu asks Google and Microsoft for each occurrence of a series inside your sync window, and creates one block per occurrence. The other calendar never receives the series rule itself.
If you move or cancel a single occurrence, only that block moves or disappears. Caltsu adds occurrences beyond the window on a later sync, once they come within range.
- Tue 7 OctBusy15:00-15:45
- Tue 14 OctBusy15:00-15:45
- Tue 21 OctBusy15:00-15:45
- Tue 28 OctOutside the 30-day window, added later
Why blocks are never copied back
With two-way sync, a block in calendar B could look like a new event. Caltsu would copy it back to calendar A, then again to B, forever. Two checks stop this.
Every block carries a hidden marker. Caltsu writes it into the event's private metadata, an extended property in Google and in Microsoft Graph. When Caltsu reads a calendar, anything with the marker is skipped. In Microsoft calendars, Caltsu also recognises a block by its note.
Every block is on record. Caltsu stores which source event each block belongs to. A second sync finds the existing block and updates it instead of adding another.
Scope and timing
| Which calendars | The primary calendar of each connected Google account and the default calendar of each connected Microsoft account. |
|---|---|
| Direction | Every calendar in your sync group sends and receives blocks. An event in any of them blocks the same time in all the others. |
| How far ahead | 30 days by default. You can set anything from 1 to 365 days in Settings. |
| What starts a sync | Google push notifications and Microsoft Graph change notifications tell Caltsu when a calendar changes. Caltsu renews these subscriptions on a schedule so they do not lapse. |
| All-day events | Become all-day blocks. |
| Stopping | Removing sync deletes every block Caltsu created. Your own events are never touched. |
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