Parsing goes through icalendar's low-level parser, which keeps properties
in order and keeps repeated ones. Writing is ours: that crate's writer
escapes a whole property value as text, so CATEGORIES:Work,Personal would
go out as one category named "Work,Personal" to every other client.
Anything the model does not interpret is carried rather than dropped --
X-MOZ-LASTACK, X-EVOLUTION-ALARM-UID, ACKNOWLEDGED, the X-MICROSOFT-CDO
set, unrecognised ATTENDEE parameters, and whole VTODO/VJOURNAL
components. A calendar has several clients writing to it and this one is
not the authority on which properties matter.
VTIMEZONE is modelled properly, and TZID is stored exactly as written:
Exchange names its zones "Pacific Standard Time", which no IANA lookup
resolves, and normalising at parse time would make the document
unrepresentable. Mapping to a real zone belongs at the point of use.
Tested against a golden corpus captured from the live Baikal (seven
producing clients over five years) and a published Outlook feed, scrubbed
of private content with the structure left byte-for-byte. Eight
hand-written fixtures cover what neither server had: DURATION, floating
times, RDATE, DST boundaries, leap day, and the full escape set.
The contract is that parse -> write -> parse is stable, plus a check that
no property name loses occurrences across the trip, since a parser that
dropped ATTENDEE entirely would round-trip perfectly and still be wrong.
VEvent and friends, transcribed from the previous calendar-models crate
and tightened so that the states which caused its timezone and recurrence
bugs cannot be represented.
The substantive changes from v1:
CalendarDateTime is an enum over the four forms RFC 5545 actually admits
(date, floating, UTC, zoned) instead of a NaiveDateTime plus a loose
Option<String> zone plus an all_day flag that could all disagree. A zoned
value carries an IANA identifier, never a UTC offset -- an offset cannot
tell standard time from daylight time, which is why recurring events
drifted an hour across DST.
EventEnd is an enum, because DTEND and DURATION are mutually exclusive.
Priority validates 0-9 on construction and on deserialisation. EditScope
replaces dispatch on strings like "this_and_future", which appeared 53
times and turned typos into silent fallthrough.
CalendarObject models a CalDAV resource as it really is: one UID, one
master, N RECURRENCE-ID overrides. v1 flattened this to a bare event list,
which made overrides look like duplicates and motivated ~500 lines of
title-matching heuristics that silently discarded events.
Dropped VJournal, VFreeBusy, VTimeZone, TodoStatus, FreeBusyType and
Period: defined but never used.
28 tests cover serde round-trips, the exact JSON shape (the model is the
wire format, so changing it should be deliberate), duration fallbacks,
validation boundaries and master/override separation.
uuid needs an explicit entropy source on wasm; without it the frontend
cannot compile the shared model. Verified that the default feature set
pulls in neither icalendar, rrule, chrono-tz, quick-xml nor reqwest.
connor