Google

Crate: adapter-google · Capabilities: calendars, tasks, contacts

Talks to the Google Calendar, Tasks, and People (Contacts) REST APIs.

Authentication

OAuth2. The host runs the OAuth flow and threads the resulting access/ refresh token to the adapter; token refresh is handled host-side. The adapter just sends a Bearer token.

Reading data

• Events: events.list with singleEvents=false, so recurring masters come through with their recurrence (RRULE/EXDATE) intact — the frontend expands occurrences. Incremental updates use a syncToken (no time bound); a 410 Gone means the token expired → full resync.
• Tasks: the Tasks API per task list.
• Contacts: the People API, including Other Contacts via its own syncToken.

Colours: Google calendars expose a backgroundColor hex, taken directly.

Quirks

• singleEvents=false + timeMin/timeMax. The full read is range bounded. Whether Google returns a recurring master whose DTSTART predates timeMin (but which recurs into the window) is Google-specific behaviour worth verifying against a real account; if a long-running series ever fails to show, this is the first suspect (drop/relax timeMin on the full read).

• 410 → resync. Treat an invalid syncToken as “start over with a full list”, then resume delta from the new token.

• One occurrence is found by its slot. Google keeps a changed or cancelled occurrence as an instance with an id of its own, and it rejects an instance id a client builds itself (HTTP 400). Updating an override, deleting one, and skipping an occurrence all look the instance up with events/{master}/instances?originalStart=…&showDeleted=true, which returns the instance in that slot however far it was moved. The adapter then writes to the id Google returned. The slot is an RFC 3339 instant, or a date for an all-day series, and the answer is compared as a parsed instant, because Google replies in the event’s own zone. An empty slot is an error: nothing is cancelled or written, and a neighbouring occurrence is never touched.

• The organizer is flagged among the attendees. Google marks the organizer’s row with organizer: true; the adapter drops it by that flag, which also holds when the address is spelled otherwise (gmail.com and googlemail.com). organizer.self says whether the calendar’s own account organizes the event, and that answer counts even without an organizer address; when it says no, the event is organized_elsewhere and only the organizer notifies. An event without an organizer is the account’s own. A PATCH replaces the whole attendees array, so an update whose invitees did not change (keep_attendees) leaves the array out, and Google’s list, the organizer’s row included, stays as it is. One that removed every invitee (clear_attendees) sends an empty array; an empty list alone leaves the array out.

• Deletions come in several spellings. Google itself deletes an occurrence as a cancelled instance, never as an EXDATE line, but other apps write EXDATE lines into the master’s recurrence, and Google returns them as written. The adapter reads every spelling seen:

  • a wall clock in a zone, EXDATE;TZID=Europe/Berlin:20260601T090000 (Google’s own export form), and without TZID, a wall clock in the series’ start.timeZone;
  • a UTC instant, EXDATE:…Z or EXDATE;VALUE=DATE-TIME:…Z. On a series of days, UTC midnight is its date: the form Aperio wrote a date in before, and no local midnight of another date falls on it;
  • a date, EXDATE;VALUE=DATE:20260601, which on a series of days names that day (its local midnight). Google ignores a date on a timed series, and so does the adapter.

  Several values on one line, any line order, names in any case and a rule with parameters (RRULE;X-…:FREQ=…) are read too. A wall clock a clock change repeats is its first reading; one it skips takes the offset from before the change, where the views place the occurrence. A zone tzdata does not know, named by TZID or by the series’ start.timeZone, costs only a wall clock on a timed series. A line the adapter does not keep (RDATE, EXRULE, an earlier of two rules, an unknown zone’s wall clock) is logged as a warning once per run.

• Deletions are written as Google spells them. The wall clock in the series’ zone with TZID, a date (VALUE=DATE) on a series of days (the only form Google’s documentation allows there), and the UTC instant on a series without a zone or for the second pass of an hour the clock shows twice. One value per line.

• A kept start, end and repeat stay out of the PATCH, together. A PATCH replaces the whole recurrence array, so an update that kept the start, the end, the all-day flag and the repeat (keep_fields) leaves all four out, and lines the adapter does not read stay on Google. They go together: Google expands the lines from the start, and a kept field may be another device’s newer change, which this device’s start must not be paired with. Before, every save, a rename included, wrote the array anew and erased deletions other apps had written.

• Zone data. Wall clocks are read and written with chrono-tz’s tzdata (2025b, the newest chrono-tz release). For a zone whose rules changed since (Casablanca and El Aaiún from 2026-09-20; Vancouver, Edmonton and Inuvik from 2026-11-01; Chișinău’s transition times), a wall clock can sit an hour from Google’s occurrence. That holds for a timed deletion written there that was not read as a wall clock in the series’ own zone — a UTC one another app wrote, say, or a wall clock in another zone: both are written as a wall clock in the series’ zone. A wall clock read in the series’ own zone and written again keeps its digits, since both directions use the same data — except one that data skips: it goes back as the reading after the change (02:30 as 03:30), the same instant in Aperio’s data. Where Google’s data has no gap there, or another one (Casablanca and El Aaiún after each Ramadan from 2027; Vancouver, Edmonton and Inuvik each March from 2027; Chișinău’s spring hour), Google reads it an hour later, and the deletion meets no occurrence.

Testing

mockito with canned Calendar/Tasks/People JSON. Tests cover the full-list vs. incremental (syncToken) paths, the 410 → full resync fallback, and the recurrence/colour mapping. A live check needs a Google account and an OAuth client configured for the Calendar/Tasks/People scopes.