From a72ff4f6e6b1e224d4973bee99913e6ee09408df Mon Sep 17 00:00:00 2001
From: Lambda <csgl@xiretza.xyz>
Date: Sun, 10 Aug 2025 19:32:12 +0000
Subject: [PATCH] MSC3575: avoid double-processing rooms in case of overlapping
 ranges

---
 src/api/client_server/sync/msc3575.rs | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/src/api/client_server/sync/msc3575.rs b/src/api/client_server/sync/msc3575.rs
index 8a98cd92..918d9f27 100644
--- a/src/api/client_server/sync/msc3575.rs
+++ b/src/api/client_server/sync/msc3575.rs
@@ -331,7 +331,7 @@ pub(crate) async fn sync_events_v4_route(
             continue;
         }
 
-        let mut new_known_rooms = BTreeSet::new();
+        let mut list_room_ids = BTreeSet::new();
 
         let mut ops = Vec::new();
         for (mut from, mut to) in list.ranges {
@@ -348,15 +348,7 @@ pub(crate) async fn sync_events_v4_route(
                     ..=to.try_into().unwrap_or(usize::MAX)]
                     .to_vec();
 
-            new_known_rooms.extend(room_ids.iter().cloned());
-            for room_id in &room_ids {
-                todo_rooms.entry(room_id.clone()).or_default().update(
-                    list.room_details.required_state.clone(),
-                    list.room_details.timeline_limit.unwrap_or(uint!(10)),
-                    known_rooms.get(&list_id),
-                    room_id,
-                );
-            }
+            list_room_ids.extend(room_ids.iter().cloned());
             ops.push(sync_events::v4::SyncOp {
                 op: SlidingOp::Sync,
                 range: Some((from, to)),
@@ -366,6 +358,15 @@ pub(crate) async fn sync_events_v4_route(
             });
         }
 
+        for room_id in &list_room_ids {
+            todo_rooms.entry(room_id.clone()).or_default().update(
+                list.room_details.required_state.clone(),
+                list.room_details.timeline_limit.unwrap_or(uint!(10)),
+                known_rooms.get(&list_id),
+                room_id,
+            );
+        }
+
         lists.insert(
             list_id.clone(),
             sync_events::v4::SyncList {
@@ -378,7 +379,7 @@ pub(crate) async fn sync_events_v4_route(
         services().users.update_sync_known_rooms(
             connection_key.clone(),
             list_id,
-            new_known_rooms,
+            list_room_ids,
             globalsince,
         );
     }