change_attendee_status() not completely async safe

[tobixen]

change_attendee_status() without an explicit attendee doesn't work for async clients

[tobixen]

⚠️ This comment is AI-generated (Claude Sonnet 4.6 via Claude Code) on behalf of tobixen ⚠️

Root cause: change_attendee_status() at calendarobjectresource.py:1238 calls self.client.principal() synchronously to auto-detect the current user's attendee line. For async clients, self.client.principal() returns a coroutine instead of a Principal object. The subsequent isinstance(attendee, Principal) check is False, so the code falls through to an email-address string comparison — but comparing against the coroutine's string representation never matches any ATTENDEE line, raising NotFoundError("Participant not found in attendee list").

Fix: add is_async_client dispatch in change_attendee_status() — if not attendee and self.is_async_client, return a coroutine that awaits self.client.principal() and then proceeds.

Workaround: always pass the attendee email explicitly:
event.change_attendee_status(attendee="user@example.com", partstat="ACCEPTED")

Discovered while making the async test suite symmetric with the sync suite (GitHub issue #667, commit c2f8dca). The async test_issue_399_change_attendee_status test works around this by passing the email explicitly.

⚠️ This comment is AI-generated (Claude Sonnet 4.6 via Claude Code) on behalf of tobixen ⚠️