Dates are interpreted in the calendar's configured zone. Returns one entry per
occurrence (recurring instances are expanded), sorted by start.

`start`/`end` are ISO 8601 (see parameter docs for zone + default-duration
details — read those before writing). `rrule` is a raw RRULE body,
e.g. "FREQ=WEEKLY;COUNT=12". `calendar` is required in practice — there
is no default calendar. Pick deliberately; events are not validated
against calendar type.

Preserves the UID and any single-occurrence exclusions/overrides. If you move
`start` without giving `end`, the duration is kept. Moving `start` re-anchors
the whole series — occurrences before the new start stop being generated (this
retimes an entire series; it does not split one at a date).

`occurrence=None` marks the whole event / series; otherwise marks only that
occurrence (via a RECURRENCE-ID override). Idempotent: re-marking replaces
the prior timestamp. The response includes `series_remaining` and
`overrides` for parity with move_occurrence / exclude_occurrence.

`occurrence` is the instance's current start exactly as returned by
`list_events`, including the UTC offset (e.g. `2026-06-18T09:00:00+12:00`).
Bare local times may not match. The response includes `series_remaining`
(occurrences left in the series) and `overrides` (RECURRENCE-ID overrides
on the series) so the rest-of-series-unchanged claim is observable.

`occurrence` is the instance's current start exactly as returned by
`list_events`, including the UTC offset (e.g. `2026-06-18T09:00:00+12:00`).
Bare local times may not match. `new_start`/`new_end` are where it moves to.
Omit `new_end` to keep the occurrence's existing duration. The rest of the
series is unchanged. The response includes `series_remaining` (occurrences
left in the series) and `overrides` (RECURRENCE-ID overrides on the series)
so the rest-of-series-unchanged claim is observable.