Robius Matrix Integration

Robius Matrix SDK Integration Skill

Selective Reading Rule

Start with:

• references/senior-master-standard.md
• references/usage-routing.md
• references/quality-checklist.md

Then load only the inherited docs, scripts, assets, or examples that match the user's actual task.

Best practices for integrating external APIs with Makepad applications based on Robrix and Moly codebases.

Source codebases:

• Robrix: Matrix SDK integration - sliding sync, timeline subscriptions, real-time updates
• Moly: OpenAI/LLM API integration - SSE streaming, MCP protocol, multi-provider support

When to Use

Use this skill when:

• Integrating Matrix SDK with Makepad
• Building a Matrix client with Makepad
• Implementing Matrix features (rooms, timelines, messages)
• Handling Matrix SDK async operations in UI
• Keywords: matrix-sdk, matrix client, robrix, matrix timeline, matrix room, sliding sync

Overview

Robrix uses the matrix-sdk and matrix-sdk-ui crates to connect to Matrix homeservers. The key architectural decisions:

1. Sliding Sync: Uses native sliding sync for efficient room list updates
2. Separate Runtime: Tokio runtime runs Matrix operations, Makepad handles UI
3. Request/Response Pattern: UI sends requests, receives actions/updates back
4. Per-Room Background Tasks: Each room has dedicated timeline subscriber task

MatrixRequest Pattern

Request Enum Definition

/// All async requests that can be made to the Matrix worker task
pub enum MatrixRequest {
    /// Login requests
    Login(LoginRequest),
    Logout { is_desktop: bool },

    /// Timeline operations
    PaginateRoomTimeline {
        room_id: OwnedRoomId,
        num_events: u16,
        direction: PaginationDirection,
    },
    SendMessage {
        room_id: OwnedRoomId,
        message: RoomMessageEventContent,
        replied_to: Option<Reply>,
    },
    EditMessage {
        room_id: OwnedRoomId,
        timeline_event_item_id: TimelineEventItemId,
        edited_content: EditedContent,
    },
    RedactMessage {
        room_id: OwnedRoomId,
        timeline_event_id: TimelineEventItemId,
        reason: Option<String>,
    },

    /// Room operations
    JoinRoom { room_id: OwnedRoomId },
    LeaveRoom { room_id: OwnedRoomId },
    GetRoomMembers {
        room_id: OwnedRoomId,
        memberships: RoomMemberships,
        local_only: bool,
    },

    /// User operations
    GetUserProfile {
        user_id: OwnedUserId,
        room_id: Option<OwnedRoomId>,
        local_only: bool,
    },
    IgnoreUser {
        ignore: bool,
        room_member: RoomMember,
        room_id: OwnedRoomId,
    },

    /// Media operations
    FetchAvatar {
        mxc_uri: OwnedMxcUri,
        on_fetched: fn(AvatarUpdate),
    },
    FetchMedia {
        media_request: MediaRequestParameters,
        on_fetched: OnMediaFetchedFn,
        destination: MediaCacheEntryRef,
        update_sender: Option<crossbeam_channel::Sender<TimelineUpdate>>,
    },

    /// Typing/read indicators
    SendTypingNotice { room_id: OwnedRoomId, typing: bool },
    ReadReceipt { room_id: OwnedRoomId, event_id: OwnedEventId },
    FullyReadReceipt { room_id: OwnedRoomId, event_id: OwnedEventId },

    /// Reactions
    ToggleReaction {
        room_id: OwnedRoomId,
        timeline_event_id: TimelineEventItemId,
        reaction: String,
    },

    /// Subscriptions
    SubscribeToTypingNotices { room_id: OwnedRoomId, subscribe: bool },
    SubscribeToPinnedEvents { room_id: OwnedRoomId, subscribe: bool },
}

Submit Pattern

static REQUEST_SENDER: Mutex<Option<UnboundedSender<MatrixRequest>>> = Mutex::new(None);

/// Submit request from UI thread to async runtime
pub fn submit_async_request(req: MatrixRequest) {
    if let Some(sender) = REQUEST_SENDER.lock().unwrap().as_ref() {
        sender.send(req).expect("BUG: matrix worker task receiver died!");
    }
}

// Usage in UI
submit_async_request(MatrixRequest::SendMessage {
    room_id: room_id.clone(),
    message: RoomMessageEventContent::text_plain(&text),
    replied_to: self.reply_to.take(),
});

Worker Task Handler

async fn matrix_worker_task(
    mut request_receiver: UnboundedReceiver<MatrixRequest>,
    login_sender: Sender<LoginRequest>,
) -> Result<()> {
    while let Some(request) = request_receiver.recv().await {
        match request {
            MatrixRequest::PaginateRoomTimeline { room_id, num_events, direction } => {
                let (timeline, sender) = {
                    let rooms = ALL_JOINED_ROOMS.lock().unwrap();
                    let Some(room_info) = rooms.get(&room_id) else {
                        continue;  // Room not ready yet
                    };
                    (room_info.timeline.clone(), room_info.update_sender.clone())
                };

                // Spawn dedicated task for this operation
                Handle::current().spawn(async move {
                    // Notify UI pagination is starting
                    sender.send(TimelineUpdate::PaginationRunning(direction)).unwrap();
                    SignalToUI::set_ui_signal();

                    // Perform pagination
                    let res = if direction == PaginationDirection::Forwards {
                        timeline.paginate_forwards(num_events).await
                    } else {
                        timeline.paginate_backwards(num_events).await
                    };

                    // Send result to UI
                    match res {
                        Ok(fully_paginated) => {
                            sender.send(TimelineUpdate::PaginationIdle {
                                fully_paginated,
                                direction,
                            }).unwrap();
                        }
                        Err(error) => {
                            sender.send(TimelineUpdate::PaginationError {
                                error,
                                direction,
                            }).unwrap();
                        }
                    }
                    SignalToUI::set_ui_signal();
                });
            }

            MatrixRequest::JoinRoom { room_id } => {
                let Some(client) = get_client() else { continue };

                Handle::current().spawn(async move {
                    let result_action = if let Some(room) = client.get_room(&room_id) {
                        match room.join().await {
                            Ok(()) => JoinRoomResultAction::Joined { room_id },
                            Err(e) => JoinRoomResultAction::Failed { room_id, error: e },
                        }
                    } else {
                        match client.join_room_by_id(&room_id).await {
                            Ok(_) => JoinRoomResultAction::Joined { room_id },
                            Err(e) => JoinRoomResultAction::Failed { room_id, error: e },
                        }
                    };
                    Cx::post_action(result_action);
                });
            }
            // ... handle other requests
        }
    }
    Ok(())
}

Timeline Updates

TimelineUpdate Enum

pub enum TimelineUpdate {
    /// New items added to timeline
    NewItems {
        new_items: Vector<Arc<TimelineItem>>,
        changed_indices: BTreeSet<usize>,
        is_append: bool,
    },
    /// Pagination state changes
    PaginationRunning(PaginationDirection),
    PaginationIdle {
        fully_paginated: bool,
        direction: PaginationDirection,
    },
    PaginationError {
        error: Error,
        direction: PaginationDirection,
    },
    /// Message edit result
    MessageEdited {
        timeline_event_id: TimelineEventItemId,
        result: Result<(), Error>,
    },
    /// Room members fetched
    RoomMembersListFetched {
        members: Vec<RoomMember>,
        sort: PrecomputedMemberSort,
        is_local_fetch: bool,
    },
    /// Unread count updated
    NewUnreadMessagesCount(UnreadMessageCount),
    /// User power levels fetched
    UserPowerLevels(UserPowerLevels),
}

Per-Room Update Flow

struct JoinedRoomDetails {
    room_id: OwnedRoomId,
    timeline: Arc<Timeline>,
    timeline_update_sender: crossbeam_channel::Sender<TimelineUpdate>,
    timeline_subscriber_handler_task: JoinHandle<()>,
    typing_notice_subscriber: Option<EventHandlerDropGuard>,
}

impl Drop for JoinedRoomDetails {
    fn drop(&mut self) {
        // Cleanup background tasks when room closes
        self.timeline_subscriber_handler_task.abort();
        drop(self.typing_notice_subscriber.take());
    }
}

// Spawn subscriber for a room
async fn spawn_timeline_subscriber(
    room_id: OwnedRoomId,
    timeline: Arc<Timeline>,
    sender: crossbeam_channel::Sender<TimelineUpdate>,
) -> JoinHandle<()> {
    tokio::spawn(async move {
        let (items, mut stream) = timeline.subscribe().await;

        // Send initial items
        sender.send(TimelineUpdate::NewItems {
            new_items: items,
            changed_indices: BTreeSet::new(),
            is_append: false,
        }).unwrap();
        SignalToUI::set_ui_signal();

        // Listen for updates
        while let Some(diff) = stream.next().await {
            let update = process_timeline_diff(diff);
            sender.send(update).unwrap();
            SignalToUI::set_ui_signal();
        }
    })
}

Handling Updates in UI

impl Widget for RoomScreen {
    fn handle_event(&mut self, cx: &mut Cx, event: &Event, scope: &mut Scope) {
        // Poll timeline updates on Signal events
        if let Event::Signal = event {
            while let Ok(update) = self.timeline_state.update_receiver.try_recv() {
                match update {
                    TimelineUpdate::NewItems { new_items, changed_indices, is_append } => {
                        self.apply_new_items(cx, new_items, changed_indices, is_append);
                    }
                    TimelineUpdate::PaginationIdle { fully_paginated, direction } => {
                        self.set_pagination_idle(cx, direction, fully_paginated);
                    }
                    TimelineUpdate::PaginationError { error, direction } => {
                        self.show_pagination_error(cx, direction, &error);
                    }
                    // ... handle other updates
                }
            }
        }

        self.view.handle_event(cx, event, scope);
    }
}

Room List Updates

RoomsListUpdate Enum

pub enum RoomsListUpdate {
    NotLoaded,
    LoadedRooms { max_rooms: Option<u32> },
    AddInvitedRoom(InvitedRoomInfo),
    AddJoinedRoom(JoinedRoomInfo),
    ClearRooms,
    UpdateLatestEvent {
        room_id: OwnedRoomId,
        timestamp: MilliSecondsSinceUnixEpoch,
        latest_message_text: String,
    },
    UpdateNumUnreadMessages {
        room_id: OwnedRoomId,
        unread_messages: UnreadMessageCount,
        unread_mentions: u64,
    },
    UpdateRoomName { new_room_name: RoomNameId },
    UpdateRoomAvatar { room_id: OwnedRoomId, avatar: FetchedRoomAvatar },
    RemoveRoom { room_id: OwnedRoomId, new_state: RoomState },
    Status { status: String },
    ScrollToRoom(OwnedRoomId),
}

static PENDING_ROOM_UPDATES: SegQueue<RoomsListUpdate> = SegQueue::new();

pub fn enqueue_rooms_list_update(update: RoomsListUpdate) {
    PENDING_ROOM_UPDATES.push(update);
    SignalToUI::set_ui_signal();
}

Client Build Pattern

async fn build_client(
    homeserver_url: &str,
    data_dir: &Path,
) -> Result<(Client, ClientSessionPersisted)> {
    // Generate unique subfolder for this session
    let db_subfolder = format!("db_{}", chrono::Local::now().format("%F_%H_%M_%S_%f"));
    let db_path = data_dir.join(db_subfolder);

    // Generate random passphrase for encryption
    let passphrase: String = {
        use rand::{Rng, thread_rng};
        thread_rng()
            .sample_iter(rand::distributions::Alphanumeric)
            .take(32)
            .map(char::from)
            .collect()
    };

    let client = Client::builder()
        .server_name_or_homeserver_url(homeserver_url)
        .sqlite_store(&db_path, Some(&passphrase))
        .sliding_sync_version_builder(VersionBuilder::DiscoverNative)
        .with_decryption_settings(DecryptionSettings {
            sender_device_trust_requirement: TrustRequirement::Untrusted,
        })
        .with_encryption_settings(EncryptionSettings {
            auto_enable_cross_signing: true,
            backup_download_strategy: BackupDownloadStrategy::OneShot,
            auto_enable_backups: true,
        })
        .request_config(
            RequestConfig::new().timeout(Duration::from_secs(60))
        )
        .build()
        .await?;

    Ok((client, ClientSessionPersisted { homeserver: homeserver_url.to_string(), db_path, passphrase }))
}

Best Practices

1. Always spawn tasks: Don't block the worker task receiver loop
2. Use crossbeam channels for per-room updates: More efficient than global queue
3. Always call SignalToUI::set_ui_signal(): After enqueueing any update
4. Handle room not ready: Skip requests for rooms not yet in ALL_JOINED_ROOMS
5. Cleanup on drop: Abort background tasks when rooms are closed
6. Use Cx::post_action for results: Posted actions are handled in App::handle_actions
7. Use SegQueue for high-frequency updates: Lock-free for room list updates

Reference Files

• references/matrix-client.md - Matrix client setup and login patterns (Robrix)
• references/timeline-handling.md - Matrix timeline subscription patterns (Robrix)
• references/moly-api-integration.md - Moly API integration patterns
  • OpenAI client with SSE streaming
  • Platform-agnostic async streams
  • MCP (Model Context Protocol) integration
  • Tool approval flow
  • MolyClient for local server
  • BotContext for multi-provider support

Limitations

• Use this skill only when the task clearly matches the scope described above.
• Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
• Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.