NaturalLanguageScheduler ignored the requested weekday and time
entirely, always returning the reference instant plus 24 hours, and
never errored on unrecognised phrasing. Every input produced a
plausible-looking event at the wrong time, which a user only discovers
by missing the meeting.
Replace it with a small, exactly-specified grammar:
<summary> today|tomorrow|YYYY-MM-DD at <time> for <duration>
Everything outside that grammar returns an error. Weekday phrasings
("next Tuesday") are refused as genuinely ambiguous rather than
resolved, since the two common readings differ by a week. A time of
day and a duration are both mandatory, so neither is defaulted.
Resolution now requires an explicit IANA time zone; a bare Unix
timestamp cannot anchor "3pm". Wall-clock times go through the zone's
DST rules and both anomalies are reported: times inside a
spring-forward gap and times inside a fall-back overlap are refused
rather than silently shifted or disambiguated. Durations are added as
elapsed time, so events spanning a transition keep their real length.
parse now returns ParsedSchedulingIntent instead of a CalendarEvent
with invented "default" account and calendar ids. There are no
in-tree callers, so no behaviour visible to a client changes.
Refs #258
james.maes