fix: Don't ignore post-messages that we have seen referenced by pre-message before

deltachat-rpc-client/tests/test_something.py

@@ -10,7 +10,7 @@
 import pytest
 
 from deltachat_rpc_client import EventType, events
-from deltachat_rpc_client.const import MessageState, DownloadState
+from deltachat_rpc_client.const import MessageState
 from deltachat_rpc_client.pytestplugin import E2EE_INFO_MSGS
 from deltachat_rpc_client.rpc import JsonRpcError
 
@@ -979,5 +979,7 @@ def test_large_message(acfactory) -> None:
     )
 
     msg = bob.wait_for_incoming_msg()
+    msgs_changed_event = bob.wait_for_msgs_changed_event()
+    assert msg.id == msgs_changed_event.msg_id
     snapshot = msg.get_snapshot()
     assert snapshot.text == "Hello World, this message is bigger than 5 bytes"

src/imap.rs

@@ -2284,11 +2284,7 @@ pub(crate) async fn prefetch_should_download(
     message_id: &str,
     mut flags: impl Iterator<Item = Flag<'_>>,
 ) -> Result<bool> {
-    if message::rfc724_mid_exists(context, message_id)
-        .await?
-        .is_some()
-    {
-        markseen_on_imap_table(context, message_id).await?;
+    if message::rfc724_mid_download_tried(context, message_id).await? {
         return Ok(false);
     }
 

src/message.rs

@@ -2176,6 +2176,32 @@ pub(crate) async fn rfc724_mid_exists_ex(
     Ok(res)
 }
 
+/// Returns `true` iff there is a message
+/// with the given `rfc724_mid`
+/// and a download state other than `DownloadState::Available`
+/// (i.e. a download state where it was already tried to download the message).
+pub(crate) async fn rfc724_mid_download_tried(context: &Context, rfc724_mid: &str) -> Result<bool> {
+    let rfc724_mid = rfc724_mid.trim_start_matches('<').trim_end_matches('>');
+    if rfc724_mid.is_empty() {
+        warn!(
+            context,
+            "Empty rfc724_mid passed to rfc724_mid_download_tried"
+        );
+        return Ok(false);
+    }
+
+    let res = context
+        .sql
+        .exists(
+            "SELECT COUNT(*) FROM msgs
+             WHERE rfc724_mid=? AND download_state<>?",
+            (rfc724_mid, DownloadState::Available),
+        )
+        .await?;
+
+    Ok(res)
+}
+
 /// Given a list of Message-IDs, returns the most relevant message found in the database.
 ///
 /// Relevance here is `(download_state == Done, index)`, where `index` is an index of Message-ID in