fix: do not sort prefetched messages by INTERNALDATE

Messages are iterated over in fetch_new_msg_batch()
and largest_uid_fetched variable is updated there
assuming that messages come in the order of increasing UID.
If UIDs are not increasing, it is possible
that largest_uid_fetched will be updated
even though smaller UID is not fetched yet
and the message will be lost.

INTERNALDATE sorting was introduced to
deal with email providers such as Gmail
that keep INTERNALDATE but not the UID
order when moving the messages.
Since we don't move the messages anymore
after commit 04c0e7d,
there is no need for ordering by INTERNALDATE.

Author: link2xt

deltachat-rpc-client/tests/test_folders.py

@@ -1,59 +1,8 @@
-import logging
 import re
-import time
 
 from imap_tools import AND, U
 
-from deltachat_rpc_client import Contact, EventType, Message
-
-
-def test_reactions_for_a_reordering_move(acfactory, direct_imap):
-    """When a batch of messages is moved from Inbox to another folder with a single MOVE command,
-    their UIDs may be reordered (e.g. Gmail is known for that) which led to that messages were
-    processed by receive_imf in the wrong order, and, particularly, reactions were processed before
-    messages they refer to and thus dropped.
-    """
-    (ac1,) = acfactory.get_online_accounts(1)
-
-    addr, password = acfactory.get_credentials()
-    ac2 = acfactory.get_unconfigured_account()
-    ac2.add_or_update_transport({"addr": addr, "password": password})
-    assert ac2.is_configured()
-
-    ac2.bring_online()
-    chat1 = acfactory.get_accepted_chat(ac1, ac2)
-    ac2.stop_io()
-
-    logging.info("sending message + reaction from ac1 to ac2")
-    msg1 = chat1.send_text("hi")
-    msg1.wait_until_delivered()
-    # It's is sad, but messages must differ in their INTERNALDATEs to be processed in the correct
-    # order by DC, and most (if not all) mail servers provide only seconds precision.
-    time.sleep(1.1)
-    react_str = "\N{THUMBS UP SIGN}"
-    msg1.send_reaction(react_str).wait_until_delivered()
-
-    logging.info("moving messages to ac2's movebox folder in the reverse order")
-    ac2_direct_imap = direct_imap(ac2)
-    ac2_direct_imap.create_folder("Movebox")
-    ac2_direct_imap.connect()
-    for uid in sorted([m.uid for m in ac2_direct_imap.get_all_messages()], reverse=True):
-        ac2_direct_imap.conn.move(uid, "Movebox")
-
-    logging.info("moving messages back")
-    ac2_direct_imap.select_folder("Movebox")
-    for uid in sorted([m.uid for m in ac2_direct_imap.get_all_messages()]):
-        ac2_direct_imap.conn.move(uid, "INBOX")
-
-    logging.info("receiving messages by ac2")
-    ac2.start_io()
-    msg2 = Message(ac2, ac2.wait_for_reactions_changed().msg_id)
-    assert msg2.get_snapshot().text == msg1.get_snapshot().text
-    reactions = msg2.get_reactions()
-    contacts = [Contact(ac2, int(i)) for i in reactions.reactions_by_contact]
-    assert len(contacts) == 1
-    assert contacts[0].get_snapshot().address == ac1.get_config("addr")
-    assert list(reactions.reactions_by_contact.values())[0] == [react_str]
+from deltachat_rpc_client import EventType
 
 
 def test_moved_markseen(acfactory, direct_imap, log):

src/imap/session.rs

@@ -16,7 +16,7 @@ use crate::net::session::SessionStream;
 /// - Autocrypt-Setup-Message to check if a message is an autocrypt setup message,
 ///   not necessarily sent by Delta Chat.
 /// - Chat-Is-Post-Message to skip it in background fetch or when it is > `DownloadLimit`.
-const PREFETCH_FLAGS: &str = "(UID INTERNALDATE RFC822.SIZE BODY.PEEK[HEADER.FIELDS (\
+const PREFETCH_FLAGS: &str = "(UID RFC822.SIZE BODY.PEEK[HEADER.FIELDS (\
                               MESSAGE-ID \
                               DATE \
                               X-MICROSOFT-ORIGINAL-MESSAGE-ID \
@@ -124,7 +124,7 @@ impl Session {
     }
 
     /// Prefetch `n_uids` messages starting from `uid_next`. Returns a list of fetch results in the
-    /// order of ascending delivery time to the server (INTERNALDATE).
+    /// order of ascending UIDs.
     #[expect(clippy::arithmetic_side_effects)]
     pub(crate) async fn prefetch(
         &mut self,
@@ -142,10 +142,10 @@ impl Session {
         let mut msgs = BTreeMap::new();
         while let Some(msg) = list.try_next().await? {
             if let Some(msg_uid) = msg.uid {
-                msgs.insert((msg.internal_date(), msg_uid), msg);
+                msgs.insert(msg_uid, msg);
             }
         }
 
-        Ok(msgs.into_iter().map(|((_, uid), msg)| (uid, msg)).collect())
+        Ok(Vec::from_iter(msgs))
     }
 }