fix(timeline): Remove UTD items that have been decrypted into unsupported events

Author: poljar

crates/matrix-sdk-ui/CHANGELOG.md

@@ -37,6 +37,11 @@ All notable changes to this project will be documented in this file.
 - [**breaking**] The MSRV has been bumped to Rust 1.88.
   ([#5431](https://github.com/matrix-org/matrix-rust-sdk/pull/5431))
 
+### Bug Fixes
+
+- Correctly remove unable-to-decrypt items that have been decrypted but contain
+  unsupported event types.
+  ([#5463](https://github.com/matrix-org/matrix-rust-sdk/pull/5463))
 
 ## [0.13.0] - 2025-07-10
 

crates/matrix-sdk-ui/src/timeline/controller/state_transaction.rs

@@ -23,7 +23,7 @@ use ruma::{
     EventId, MilliSecondsSinceUnixEpoch, OwnedEventId, OwnedTransactionId, OwnedUserId, UserId,
     events::AnySyncTimelineEvent, push::Action, serde::Raw,
 };
-use tracing::{debug, instrument, warn};
+use tracing::{debug, instrument, trace, warn};
 
 use super::{
     super::{
@@ -684,7 +684,7 @@ impl<'a, P: RoomDataProvider> TimelineStateTransaction<'a, P> {
         .await;
 
         // Handle the event to create or update a timeline item.
-        if let Some(timeline_action) = timeline_action {
+        let item_added = if let Some(timeline_action) = timeline_action {
             let sender_profile = room_data_provider.profile_from_user_id(&sender).await;
 
             let ctx = TimelineEventContext {
@@ -715,9 +715,25 @@ impl<'a, P: RoomDataProvider> TimelineStateTransaction<'a, P> {
                 .handle_event(date_divider_adjuster, timeline_action)
                 .await
         } else {
-            // No item has been removed from the timeline.
+            // No item has been added to the timeline.
             false
+        };
+
+        let mut item_removed = false;
+
+        if !item_added {
+            trace!("No new item added");
+
+            if let TimelineItemPosition::UpdateAt { timeline_item_index } = position {
+                // If add was not called, that means the UTD event is one that
+                // wouldn't normally be visible. Remove it.
+                trace!("Removing UTD that was successfully retried");
+                self.items.remove(timeline_item_index);
+                item_removed = true;
+            }
         }
+
+        item_removed
     }
 
     /// Remove one timeline item by its `event_index`.

crates/matrix-sdk-ui/src/timeline/event_handler.rs

@@ -473,7 +473,14 @@ impl<'a, 'o> TimelineEventHandler<'a, 'o> {
 
     /// Handle an event.
     ///
-    /// Returns the number of timeline updates that were made.
+    /// Returns if an item was added to the timeline due to the new timeline
+    /// action. Items might not be added to the timeline for various reasons,
+    /// some common ones are if the item:
+    ///     - Contains an unsupported event type.
+    ///     - Is an edit or a redaction.
+    ///     - Contains a local echo turning into a remote echo.
+    ///     - Contains a message that is already in the timeline but was now
+    ///       decrypted.
     ///
     /// `raw_event` is only needed to determine the cause of any UTDs,
     /// so if we know this is not a UTD it can be None.
@@ -482,7 +489,7 @@ impl<'a, 'o> TimelineEventHandler<'a, 'o> {
         mut self,
         date_divider_adjuster: &mut DateDividerAdjuster,
         timeline_action: TimelineAction,
-    ) -> RemovedItem {
+    ) -> bool {
         let span = tracing::Span::current();
 
         date_divider_adjuster.mark_used();
@@ -541,25 +548,7 @@ impl<'a, 'o> TimelineEventHandler<'a, 'o> {
             },
         }
 
-        let mut removed_item = false;
-
-        if !added_item {
-            trace!("No new item added");
-
-            if let Flow::Remote {
-                position: TimelineItemPosition::UpdateAt { timeline_item_index },
-                ..
-            } = self.ctx.flow
-            {
-                // If add was not called, that means the UTD event is one that
-                // wouldn't normally be visible. Remove it.
-                trace!("Removing UTD that was successfully retried");
-                self.items.remove(timeline_item_index);
-                removed_item = true;
-            }
-        }
-
-        removed_item
+        added_item
     }
 
     #[instrument(skip(self, edit_kind))]