Ensure the client does not busy loop
skipping IDLE if UIDNEXT of the mailbox is higher than
the last seen UID plus 1, e.g. if the message
with UID=UIDNEXT-1 was deleted before we fetched it.
We do not fallback to UIDNEXT=1 anymore
if the STATUS command cannot determine UIDNEXT.
There are no known IMAP servers with broken STATUS so far.
This allows to guarantee that select_with_uidvalidity()
sets UIDNEXT for the mailbox and use it in fetch_new_messages()
to ensure that UIDNEXT always advances even
when there are no messages to fetch.
Before, it was shown by UI when the chat is empty, however, in case of
verified groups, this is never the case any longer as the 'e2ee now
guaranteed' is always added.
Green checkmark in the contact profile
should only be displayed in the title
if the same checkmark is displayed in the title of 1:1 chat.
If 1:1 chat does not exist,
the checkmark should not be displayed in the title
of the contact profile.
Also add docs to is_protected
property of FullChat and BasicChat JSON objects.
This prevents accidentally going IDLE
when the last new message has arrived
while the folder was closed.
For example, this happened in some tests:
1. INBOX is selected to fetch, move and delete messages.
2. One of the messages is deleted.
3. INBOX is closed to expunge the message.
4. A new message arrives.
5. INBOX is selected with (CONDSTORE) to sync flags.
6. Delta Chat goes into IDLE without downloading the new message.
To determine that a new message has arrived
we need to notice that UIDNEXT has advanced when selecting the folder.
However, some servers such as Winmail Pro Mail Server 5.1.0616
do not return UIDNEXT in response to SELECT command.
To avoid interdependencies with the code
SELECTing the folder and having to implement
STATUS fallback after each SELECT even when we
may not want to go IDLE due to interrupt or unsolicited EXISTS,
we simply call STATUS unconditionally before IDLE.
Sync messages are only sent on explicit user actions and only one per action, so it's safe to send
them right away not worrying about the rate limit on the server.
This may happen if autocrypt key is changed after verification.
UI should still display who introduced the contact,
especially if the contact is still a member of some verified group.
If the contact is at the same time not verified,
i.e. its autocrypt key does not match verified key,
UI may display a crossed out checkmark instead of green checkmark.
Result::Err is reserved for local errors,
such as database failures.
Not found peerstate in the database is a protocol failure,
so just return Ok(false) in mark_peer_as_verified().
This allows to handle more errors with `?`.
