Calendar

Tachyon speaks CalDAV. It is a calendar client, not a calendar server: events live on your CalDAV server and Tachyon shows and edits them.

Added in 4.0.

Turning it on

The calendar is off until an administrator enables it. In the Admin Panel under Config, or directly in application.ini:

[calendar]
enable = On
allow_sync = On

allow_sync is what lets users connect their own server from their settings. Every option is described in the admin manual.

Once enabled, a calendar entry appears in the menu at the top right, beside Contacts.

Connecting a server

Settings, Calendar. Fill in the URL, user and passphrase, then press Test.

The URL is the CalDAV endpoint, not a single calendar. Tachyon discovers the calendars from it, so one address gives you all of them. For a few common servers:

Server	URL
Nextcloud	https://example.com/nextcloud/remote.php/dav
ownCloud	https://example.com/owncloud/remote.php/dav
Radicale	https://example.com/radicale/
Baïkal	https://example.com/dav.php

Discovery follows .well-known/caldav, then the current user principal, then the calendar home set, and collects every calendar collection it finds. If your server does not advertise those, point the URL straight at the calendar home, for example https://example.com/nextcloud/remote.php/dav/calendars/username/.

Test reports what actually happened. Some messages worth recognising:

Message	Meaning
Connection succeeded	Tachyon reached the server, authenticated, and found at least one calendar.
No calendars found at this address	It connected and authenticated, but nothing at that address is a calendar collection. Usually the URL points somewhere above or below the calendars.
No DAV client	The URL, user or passphrase is incomplete.
An HTTP status or TLS error	Passed through from the server. A 404 from a server behind a reverse proxy often means the credentials were rejected rather than the address being wrong.

Using it

The calendar list on the left toggles which calendars are shown. A calendar the server marks read-only is labelled with a lock, and Tachyon will not offer to write to it.

• New event on the toolbar, or drag across empty space in the grid
• Drag an event to move it, or drag its edge to change the length
• Click an event to edit it
• Month, week, day and list views, with the arrows and Today to navigate
• The sync button pulls changes from the server

Times follow the hour format in Settings, General. If you see AM and PM and would rather not, set it to 00:00 (24 hour) there; it applies everywhere, including the calendar.

What is not supported yet

• Repeating events are read only. They display and expand correctly, including across daylight saving changes, but the editor will not save changes to them. Saving rebuilds an event from the fields in the form, which carry no recurrence rule, so writing one back would quietly turn a series into a single event. Real series editing needs this instance / this and future / all semantics, which is a feature of its own.
• Task lists. A calendar holding VTODO items synchronises without complaint and simply shows nothing from them.
• Invitations. Meeting requests are not sent or answered.
• Local calendars. Every calendar comes from a server. A calendar stored only in Tachyon would be invisible to every other client, which needs Tachyon to speak CalDAV as a server rather than a client.
• Reminders are not implemented. When they are, they will only fire while a Tachyon tab is open.

Notes for administrators

The calendar stores what it syncs in its own tables, separate from contacts, and creates them on first use. It keeps each event's original iCalendar body as the source of truth, with extracted columns used only for querying, so a round trip back to the server preserves anything Tachyon does not itself understand.

calendar.min.js is around 129 KB, and is fetched only when a user first opens the calendar. Installations that leave the feature off never download it.