process unread messages on restart by registering handlers before initial sync

src/main.rs

@@ -114,7 +114,12 @@ async fn sync(
     session_file: &std::path::Path,
     state: Arc<Mutex<DaemonState>>,
 ) -> anyhow::Result<()> {
-    tracing::info!("initial sync (ignoring past messages)");
+    let has_token = initial_sync_token.is_some();
+    if has_token {
+        tracing::info!("restoring with persisted token, will process unread messages");
+    } else {
+        tracing::info!("first start, ignoring historical messages");
+    }
 
     let filter = FilterDefinition::with_lazy_loading();
     let mut sync_settings = SyncSettings::default().filter(filter.into());
@@ -123,6 +128,13 @@ async fn sync(
         sync_settings = sync_settings.token(token);
     }
 
+    // Register handlers BEFORE sync_once iff we have a token, so messages
+    // received while we were down trigger the queue. On first start we skip
+    // this to avoid backlogging every historical message.
+    if has_token {
+        register_event_handlers(&client, state.clone());
+    }
+
     loop {
         match client.sync_once(sync_settings.clone()).await {
             Ok(response) => {
@@ -136,8 +148,18 @@ async fn sync(
         }
     }
 
+    if !has_token {
+        register_event_handlers(&client, state.clone());
+    }
+
     tracing::info!("synced, listening for messages");
 
+    client.sync(sync_settings).await?;
+
+    bail!("sync loop exited unexpectedly")
+}
+
+fn register_event_handlers(client: &Client, state: Arc<Mutex<DaemonState>>) {
     let msg_state = state.clone();
     client.add_event_handler(
         move |event: matrix_sdk::ruma::events::room::message::OriginalSyncRoomMessageEvent,
@@ -160,10 +182,6 @@ async fn sync(
     );
 
     client.add_event_handler(handlers::on_stripped_state_member);
-
-    client.sync(sync_settings).await?;
-
-    bail!("sync loop exited unexpectedly")
 }
 
 async fn process_loop(state: Arc<Mutex<DaemonState>>, client: Client, socket_path: &PathBuf) {