Standard CalDAV/CardDAV clients (Thunderbird, DAVx5, Apple
Calendar/Contacts) failed to connect, mounted collections read-only, or
could not discover address books, even though curl worked. Three
protocol-compliance gaps caused this:
1. Missing Basic-auth challenge on /caldav and /carddav.
The 401 returned for these surfaces carried no `WWW-Authenticate`
header (only /webdav did). Spec-compliant clients never send
credentials preemptively the way `curl -u` does — they wait for the
challenge — so Thunderbird never authenticated and failed with
"discovery failed" / 401. Extend the challenge to all DAV surfaces via
shared `is_dav_path` / `dav_basic_auth_challenge` helpers.
2. Calendars always advertised read-only.
The `current-user-privilege-set` write gate compared `owner_id`
against the literal string "current_user_id", which never matched a
real UUID, so `<D:write/>` was never emitted and clients mounted every
calendar read-only. Thread the caller's id through the CalDAV adapter
and grant write when the caller owns the calendar.
3. CardDAV discovery was incomplete.
There was no `/.well-known/carddav` route and the root PROPFIND
exposed neither `current-user-principal` nor `addressbook-home-set`,
so clients could not locate address books. Add the well-known redirect
and root/principal discovery responses mirroring the CalDAV adapter.
Adds unit tests for the auth challenge predicate, the calendar
owner/non-owner privilege split, and the CardDAV root/principal discovery
responses.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016cVV9nRQjP6G6a8zbNUWMw
Claude
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