Merge branch 'fix/channel-cache-miss' into 'master'

fix(backend): Return cached Channel from channel_from_uuid_or_group

See merge request schmiddi-on-mobile/flare!214

src/backend/manager.rs

@@ -490,6 +490,16 @@ impl Manager {
             Thread::Contact(uuid)
         };
 
+        // Fast path: if we already know this thread, return the cached
+        // `Channel` so callers see notify-signals (e.g. `is-typing`) on the
+        // same GObject instance the UI is bound to. Without this, the
+        // incoming `TypingMessage` handler would toggle `is-typing` on a
+        // freshly-built orphan `Channel` and the typing indicator would
+        // silently never light up for known contacts.
+        if let Some(cached) = self.imp().channels.borrow().get(&thread).cloned() {
+            return cached;
+        }
+
         let contact = Contact::from_service_address(&uuid, self).await;
         let channel = Channel::from_contact_or_group(contact, group, self).await;
         channel.initialize_avatar().await;
@@ -977,3 +987,49 @@ mod imp {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use libsignal_service::prelude::Uuid;
+    use libsignal_service::protocol::ServiceId;
+
+    /// Regression test for the channel-cache miss in
+    /// [`Manager::channel_from_uuid_or_group`].
+    ///
+    /// The function previously always built and returned a fresh
+    /// `Channel` GObject, even when one for the same thread already
+    /// lived in the cache. Property notifications (e.g. `is-typing`
+    /// for incoming `TypingMessage`s) were therefore emitted on an
+    /// orphan instance the UI was not bound to, and indicators
+    /// silently never reflected the change. This test asserts the
+    /// invariant that a cached thread short-circuits to the cached
+    /// `Channel` instance.
+    #[test]
+    fn cached_thread_returns_cached_channel() {
+        gtk::init().expect("gtk to initialize");
+        let manager: Manager = glib::Object::new();
+        let cached: Channel = glib::Object::new();
+        let uuid = Uuid::from_u128(0x1);
+        let thread = Thread::Contact(ServiceId::Aci(uuid.into()));
+
+        manager
+            .imp()
+            .channels
+            .borrow_mut()
+            .insert(thread, cached.clone());
+
+        let runtime = tokio::runtime::Builder::new_current_thread()
+            .enable_all()
+            .build()
+            .expect("tokio current-thread runtime to build");
+        let result = runtime
+            .block_on(manager.channel_from_uuid_or_group(ServiceId::Aci(uuid.into()), &None));
+
+        assert!(
+            cached.eq(&result),
+            "channel_from_uuid_or_group must return the cached `Channel` instance \
+             so notify-signals reach widgets bound to it"
+        );
+    }
+}