Google Calendar Integration
You can connect your Focus account to Google Calendar and keep events synchronized. This page explains how it works.
Connecting to Google Calendar
You can find the action to connect your personal cloud to a Google Calendar in user settings behind the three dots menu. You will be asked to allow Focus access to your calendar. Focus will only link to your "primary" calendar within Google Calendar, not any secondary ones.
Multiple clouds and calendars
If you have multiple Google accounts you can connect to them, too. However, you can only connect one cloud to one calendar. Clouds also have a "Link with Google Calendar" action, so to link to another account's calendar navigate to an appropriate cloud and link from there. Create a new cloud if necessary.
Creating events
Events created in Google Calendar will appear in Focus as appointment activities in the cloud that was linked (normally your personal cloud). Appointments and other activities created in Focus will not be sent over to Google Calendar.
Updating events and activities
The connection is one-way from Google Calendar to Focus. This is because the integration does not allow sending updated invitations to other people, for example.

The Focus activity counterpart of an event created in Google Calendar is updated when the name, dates or description are changed in Google Calendar.

Changes made in Focus do not update the Google Calendar event, but you can add content to the feed and change Focus-only fields such as attachments and tags.

An activity can be moved to a different cloud without losing its connection to the event. You can also change the activity type.
Deleting events
To delete an event, delete it from Google Calendar. An activity may be shared with others so this will only remove you as an actor from the activity in Focus. After deleting an event in Google Calendar you can also delete its Focus counterpart activity. If you only delete the Focus activity the Google Calendar event will remain.
Sharing events and activities with others
You can share events with others in Google Calendar and activities with others in Focus and this leads to some quirks if you do both. Here is an example:

Alice and Bob use both Google Calendar and Focus and have linked their personal clouds with their calendars. Alice creates an event and shares it with Bob (in Google Calendar). Two different Focus activities are created, one in Alice's personal cloud and one in Bob's. Alice moves her activity into a cloud that they both share. Bob now has two activities for the same event. Bob can resolve the situation by deleting the personal activity in Focus only. His corresponding Google Calendar event will remain synchronized via Alice's account.

To avoid the duplicate Alice can create the event in Google Calendar without sharing it with Bob at first. Then she can share it with Bob in Focus and after that share in Google Calendar, too. This way Bob already has access to the shared activity in Focus when the event appears in Google Calendar and they can be synchronized.
Recurring events
Only the first occurrence of a recurring event is synchronized to Focus. It is a best practice to move the same activity to when it happens next in Focus instead of marking it as finished because this way the activity feed has continuity.
The event location is currently not synchronized, because the storage format is incompatible. Google Calendar stores the location as an address while Focus stores it as a geographical location.