feat(lib): chat-room protocol (list, join, leave, say) with events

Implement the Soulseek chat-room server messages against soulfind's
wire format:
- MessageFactory builders: room-list request (64), join (14),
  leave (15), say (13).
- Handlers parsing the server side: RoomList (64) names+counts,
  JoinRoom (14) membership, SayChatroom (13), UserJoinedRoom (16),
  UserLeftRoom (17), LeaveRoom (15).
- Surface everything to the client as a drained RoomEvent stream plus
  a room-list snapshot; new Client API: request_room_list, join_room,
  leave_room, say_in_room, room_list, take_room_events.

Unit tests cover each builder and handler; server-gated e2e tests
exercise message delivery and room listing against soulfind.

soulseek-rs-lib/src/actor/server_actor.rs

@@ -5,6 +5,8 @@ use crate::message::server::ConnectToPeerHandler;
 use crate::message::server::ExcludedSearchPhrasesHandler;
 use crate::message::server::FileSearchHandler;
 use crate::message::server::GetPeerAddressHandler;
+use crate::message::server::JoinRoomHandler;
+use crate::message::server::LeaveRoomHandler;
 use crate::message::server::LoginHandler;
 use crate::message::server::MessageFactory;
 use crate::message::server::MessageUser;
@@ -12,11 +14,15 @@ use crate::message::server::ParentMinSpeedHandler;
 use crate::message::server::ParentSpeedRatioHandler;
 use crate::message::server::PrivilegedUsersHandler;
 use crate::message::server::RoomListHandler;
+use crate::message::server::SayChatroomHandler;
+use crate::message::server::UserJoinedRoomHandler;
+use crate::message::server::UserLeftRoomHandler;
 use crate::message::server::WishListIntervalHandler;
 use crate::message::{Handlers, MessageType};
 use crate::message::{Message, MessageReader};
 use crate::peer::ConnectionType;
 use crate::peer::Peer;
+use crate::types::{RoomEvent, RoomInfo};
 use crate::utils::lock::RwLockExt;
 
 use std::io::{self, Error, Write};
@@ -168,6 +174,27 @@ pub enum ServerMessage {
         obfuscated_port: u16,
     },
     PrivateMessageReceived(UserMessage),
+    RoomListReceived(Vec<RoomInfo>),
+    RoomJoined {
+        room: String,
+        users: Vec<String>,
+    },
+    RoomLeft {
+        room: String,
+    },
+    RoomMessageReceived {
+        room: String,
+        username: String,
+        message: String,
+    },
+    RoomUserJoined {
+        room: String,
+        username: String,
+    },
+    RoomUserLeft {
+        room: String,
+        username: String,
+    },
 }
 
 pub struct ServerActor {
@@ -327,6 +354,11 @@ impl ServerActor {
 
         handlers.register_handler(LoginHandler);
         handlers.register_handler(RoomListHandler);
+        handlers.register_handler(JoinRoomHandler);
+        handlers.register_handler(LeaveRoomHandler);
+        handlers.register_handler(SayChatroomHandler);
+        handlers.register_handler(UserJoinedRoomHandler);
+        handlers.register_handler(UserLeftRoomHandler);
         handlers.register_handler(ExcludedSearchPhrasesHandler);
         handlers.register_handler(PrivilegedUsersHandler);
         handlers.register_handler(MessageUser);
@@ -468,6 +500,35 @@ impl ServerActor {
                     );
                 }
             }
+            ServerMessage::RoomListReceived(rooms) => {
+                self.forward_room_event(RoomEvent::List(rooms));
+            }
+            ServerMessage::RoomJoined { room, users } => {
+                self.forward_room_event(RoomEvent::Joined { room, users });
+            }
+            ServerMessage::RoomLeft { room } => {
+                self.forward_room_event(RoomEvent::Left { room });
+            }
+            ServerMessage::RoomMessageReceived {
+                room,
+                username,
+                message,
+            } => {
+                self.forward_room_event(RoomEvent::Message {
+                    room,
+                    username,
+                    message,
+                });
+            }
+            ServerMessage::RoomUserJoined { room, username } => {
+                self.forward_room_event(RoomEvent::UserJoined {
+                    room,
+                    username,
+                });
+            }
+            ServerMessage::RoomUserLeft { room, username } => {
+                self.forward_room_event(RoomEvent::UserLeft { room, username });
+            }
             ServerMessage::ProcessRead => {
                 self.process_read();
             }
@@ -602,6 +663,15 @@ impl ServerActor {
         self.process_dispatcher_messages();
     }
 
+    /// Forward a chat-room event to the client operations loop.
+    fn forward_room_event(&self, event: RoomEvent) {
+        if let Err(e) =
+            self.client_channel.send(ClientOperation::RoomEvent(event))
+        {
+            error!("[server] Error forwarding room event to client: {}", e);
+        }
+    }
+
     fn queue_message(&mut self, message: Message) {
         if let Some(sender) = &self.dispatcher_sender {
             match sender.send(ServerMessage::SendMessage(message)) {

soulseek-rs-lib/src/client.rs

@@ -3,7 +3,7 @@ use crate::actor::server_actor::{
     PeerAddress, ServerActor, ServerMessage, UserMessage,
 };
 use crate::download_store::{DownloadStore, collect_failed_tokens};
-use crate::types::{DownloadMetadata, DownloadStatus};
+use crate::types::{DownloadMetadata, DownloadStatus, RoomEvent, RoomInfo};
 use crate::utils::logger;
 use crate::{
     Transfer,
@@ -186,6 +186,9 @@ pub enum ClientOperation {
     /// established — the peer is likely firewalled, so fall back to asking the
     /// server to broker the connection. Carries the reporting actor's id.
     PeerConnectFailed(u64, String),
+    /// Something happened in the chat-room subsystem (list refreshed, a room
+    /// joined/left, a message said, a member joined/left).
+    RoomEvent(RoomEvent),
 }
 pub struct ClientContext {
     pub peer_registry: Option<PeerRegistry>,
@@ -209,6 +212,10 @@ pub struct ClientContext {
     pending_serves: HashMap<String, Vec<u32>>,
     /// Shared-file listings received from peers we browsed.
     browse_results: HashMap<String, Vec<SharedDirectory>>,
+    /// Latest snapshot of the public chat-room list (from `RoomList`, code 64).
+    room_list: Vec<RoomInfo>,
+    /// Chat-room events awaiting consumption by the client/UI.
+    room_events: Vec<RoomEvent>,
     actor_system: Arc<ActorSystem>,
 }
 impl Default for ClientContext {
@@ -499,11 +506,34 @@ impl ClientContext {
             uploads: HashMap::new(),
             pending_serves: HashMap::new(),
             browse_results: HashMap::new(),
+            room_list: Vec::new(),
+            room_events: Vec::new(),
             downloads: DownloadStore::new(),
             actor_system,
         }
     }
 
+    /// Apply a chat-room event: keep the room-list snapshot current and queue
+    /// the event for the client/UI to drain.
+    pub fn apply_room_event(&mut self, event: RoomEvent) {
+        if let RoomEvent::List(rooms) = &event {
+            self.room_list.clone_from(rooms);
+        }
+        self.room_events.push(event);
+    }
+
+    /// The latest snapshot of the public chat-room list.
+    #[must_use]
+    pub fn room_list(&self) -> Vec<RoomInfo> {
+        self.room_list.clone()
+    }
+
+    /// Remove and return all chat-room events received since the last call.
+    #[must_use]
+    pub fn take_room_events(&mut self) -> Vec<RoomEvent> {
+        std::mem::take(&mut self.room_events)
+    }
+
     /// Cache a peer's listen address learned from a GetPeerAddress response.
     pub fn cache_peer_address(
         &mut self,
@@ -746,6 +776,93 @@ impl Client {
         Ok(())
     }
 
+    /// Send a raw server message via the server actor, mapping a dead channel
+    /// to [`SoulseekRs::NotConnected`].
+    fn send_server_message(
+        &self,
+        message: crate::message::Message,
+    ) -> Result<()> {
+        self.server_handle
+            .as_ref()
+            .ok_or(SoulseekRs::NotConnected)?
+            .send(ServerMessage::SendMessage(message))
+            .map_err(|_| SoulseekRs::NotConnected)?;
+        Ok(())
+    }
+
+    /// Ask the server for the list of public chat rooms. The response arrives
+    /// asynchronously; read it with [`Client::room_list`] or by draining
+    /// [`Client::take_room_events`] for a [`RoomEvent::List`].
+    ///
+    /// # Errors
+    /// Returns [`SoulseekRs::NotConnected`] if the client is not connected.
+    pub fn request_room_list(&self) -> Result<()> {
+        self.send_server_message(
+            crate::message::server::MessageFactory::build_room_list_request(),
+        )
+    }
+
+    /// Join a public chat room. The membership list and subsequent messages
+    /// arrive via [`Client::take_room_events`].
+    ///
+    /// # Errors
+    /// Returns [`SoulseekRs::NotConnected`] if the client is not connected.
+    pub fn join_room(&self, room: &str) -> Result<()> {
+        self.send_server_message(
+            crate::message::server::MessageFactory::build_join_room(
+                room, false,
+            ),
+        )
+    }
+
+    /// Leave a chat room previously joined with [`Client::join_room`].
+    ///
+    /// # Errors
+    /// Returns [`SoulseekRs::NotConnected`] if the client is not connected.
+    pub fn leave_room(&self, room: &str) -> Result<()> {
+        self.send_server_message(
+            crate::message::server::MessageFactory::build_leave_room(room),
+        )
+    }
+
+    /// Say `message` in chat room `room`. The server echoes it back as a
+    /// [`RoomEvent::Message`], so the UI should render from that echo rather
+    /// than optimistically.
+    ///
+    /// # Errors
+    /// Returns [`SoulseekRs::NotConnected`] if the client is not connected.
+    pub fn say_in_room(&self, room: &str, message: &str) -> Result<()> {
+        self.send_server_message(
+            crate::message::server::MessageFactory::build_say_chatroom(
+                room, message,
+            ),
+        )
+    }
+
+    /// The latest snapshot of the public chat-room list.
+    #[must_use]
+    pub fn room_list(&self) -> Vec<RoomInfo> {
+        match self.context.read_safe() {
+            Ok(ctx) => ctx.room_list(),
+            Err(e) => {
+                error!("[client] room_list: {}", e);
+                Vec::new()
+            }
+        }
+    }
+
+    /// Remove and return all chat-room events received since the last call.
+    #[must_use]
+    pub fn take_room_events(&self) -> Vec<RoomEvent> {
+        match self.context.write_safe() {
+            Ok(mut ctx) => ctx.take_room_events(),
+            Err(e) => {
+                error!("[client] take_room_events: {}", e);
+                Vec::new()
+            }
+        }
+    }
+
     /// Request a peer's shared-file listing. When it arrives it can be
     /// retrieved with [`Client::take_browse_result`].
     ///
@@ -1654,6 +1771,15 @@ impl Client {
                                     e
                                 ),
                             },
+                            ClientOperation::RoomEvent(event) => {
+                                match client_context.write_safe() {
+                                    Ok(mut ctx) => ctx.apply_room_event(event),
+                                    Err(e) => error!(
+                                        "[client] RoomEvent write: {}",
+                                        e
+                                    ),
+                                }
+                            }
                             ClientOperation::PeerConnected(username) => {
                                 // An outbound control connection just handshook.
                                 // Flush any downloads that were queued for this

soulseek-rs-lib/src/message/server/join_room.rs

@@ -0,0 +1,52 @@
+use crate::{
+    actor::server_actor::ServerMessage,
+    message::{Message, MessageHandler},
+};
+use std::sync::mpsc::Sender;
+
+pub struct JoinRoomHandler;
+
+impl MessageHandler<ServerMessage> for JoinRoomHandler {
+    fn get_code(&self) -> u8 {
+        14
+    }
+
+    fn handle(&self, message: &mut Message, sender: Sender<ServerMessage>) {
+        // JoinRoom (code 14): room name, then a vector of member usernames.
+        // Per-user stat vectors follow but are not needed here, so we stop
+        // after reading the names.
+        let room = message.read_string();
+        let user_count = message.read_int32();
+        let mut users = Vec::new();
+        for _ in 0..user_count {
+            users.push(message.read_string());
+        }
+        let _ = sender.send(ServerMessage::RoomJoined { room, users });
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn forwards_room_and_member_list() {
+        let (tx, rx) = std::sync::mpsc::channel();
+        let mut message = Message::new();
+        message.write_raw_bytes(vec![0u8; 8]);
+        message.write_string("nicotine");
+        message.write_int32(2);
+        message.write_string("alice");
+        message.write_string("bob");
+        message.set_pointer(8);
+
+        JoinRoomHandler.handle(&mut message, tx);
+        match rx.try_recv() {
+            Ok(ServerMessage::RoomJoined { room, users }) => {
+                assert_eq!(room, "nicotine");
+                assert_eq!(users, vec!["alice", "bob"]);
+            }
+            other => panic!("unexpected: {other:?}"),
+        }
+    }
+}

soulseek-rs-lib/src/message/server/leave_room.rs

@@ -0,0 +1,38 @@
+use crate::{
+    actor::server_actor::ServerMessage,
+    message::{Message, MessageHandler},
+};
+use std::sync::mpsc::Sender;
+
+pub struct LeaveRoomHandler;
+
+impl MessageHandler<ServerMessage> for LeaveRoomHandler {
+    fn get_code(&self) -> u8 {
+        15
+    }
+
+    fn handle(&self, message: &mut Message, sender: Sender<ServerMessage>) {
+        let room = message.read_string();
+        let _ = sender.send(ServerMessage::RoomLeft { room });
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn forwards_left_room() {
+        let (tx, rx) = std::sync::mpsc::channel();
+        let mut message = Message::new();
+        message.write_raw_bytes(vec![0u8; 8]);
+        message.write_string("jazz");
+        message.set_pointer(8);
+
+        LeaveRoomHandler.handle(&mut message, tx);
+        match rx.try_recv() {
+            Ok(ServerMessage::RoomLeft { room }) => assert_eq!(room, "jazz"),
+            other => panic!("unexpected: {other:?}"),
+        }
+    }
+}

soulseek-rs-lib/src/message/server/message_factory.rs

@@ -122,6 +122,38 @@ impl MessageFactory {
             .clone()
     }
 
+    /// Ask the server (code 64) for the list of public chat rooms.
+    #[must_use]
+    pub fn build_room_list_request() -> Message {
+        Message::new().write_int32(64).clone()
+    }
+
+    /// Join a chat room (server code 14). `private` requests a private room.
+    #[must_use]
+    pub fn build_join_room(room: &str, private: bool) -> Message {
+        Message::new()
+            .write_int32(14)
+            .write_string(room)
+            .write_int32(u32::from(private))
+            .clone()
+    }
+
+    /// Leave a chat room (server code 15).
+    #[must_use]
+    pub fn build_leave_room(room: &str) -> Message {
+        Message::new().write_int32(15).write_string(room).clone()
+    }
+
+    /// Say `message` in chat room `room` (server code 13).
+    #[must_use]
+    pub fn build_say_chatroom(room: &str, message: &str) -> Message {
+        Message::new()
+            .write_int32(13)
+            .write_string(room)
+            .write_string(message)
+            .clone()
+    }
+
     /// Ask a peer for their shared-file listing (peer code 4, no body).
     #[must_use]
     pub fn build_get_share_file_list() -> Message {
@@ -272,6 +304,47 @@ fn test_build_message_acked() {
     assert_eq!(expect, message.get_data());
 }
 
+#[test]
+fn test_build_join_room() {
+    let message = MessageFactory::build_join_room("nicotine", false);
+    let expect: Vec<u8> = [
+        14, 0, 0, 0, // code
+        8, 0, 0, 0, 110, 105, 99, 111, 116, 105, 110, 101, // "nicotine"
+        0, 0, 0, 0, // private = 0
+    ]
+    .to_vec();
+    assert_eq!(expect, message.get_data());
+}
+
+#[test]
+fn test_build_leave_room() {
+    let message = MessageFactory::build_leave_room("nicotine");
+    let expect: Vec<u8> = [
+        15, 0, 0, 0, // code
+        8, 0, 0, 0, 110, 105, 99, 111, 116, 105, 110, 101, // "nicotine"
+    ]
+    .to_vec();
+    assert_eq!(expect, message.get_data());
+}
+
+#[test]
+fn test_build_say_chatroom() {
+    let message = MessageFactory::build_say_chatroom("room", "hi");
+    let expect: Vec<u8> = [
+        13, 0, 0, 0, // code
+        4, 0, 0, 0, 114, 111, 111, 109, // "room"
+        2, 0, 0, 0, 104, 105, // "hi"
+    ]
+    .to_vec();
+    assert_eq!(expect, message.get_data());
+}
+
+#[test]
+fn test_build_room_list_request() {
+    let message = MessageFactory::build_room_list_request();
+    assert_eq!(vec![64, 0, 0, 0], message.get_data());
+}
+
 #[test]
 fn test_build_file_search_message() {
     let message = MessageFactory::build_file_search_message(12, "trance wax");

soulseek-rs-lib/src/message/server/mod.rs

@@ -2,6 +2,8 @@ mod connect_to_peer;
 mod excluded_search_phrases;
 mod file_search;
 mod get_peer_address;
+mod join_room;
+mod leave_room;
 mod login;
 mod message_factory;
 mod message_user;
@@ -9,12 +11,17 @@ mod parent_min_speed;
 mod parent_speed_ratio;
 mod privileged_users;
 mod room_list;
+mod say_chatroom;
+mod user_joined_room;
+mod user_left_room;
 mod wish_list_interval;
 
 pub use connect_to_peer::ConnectToPeerHandler;
 pub use excluded_search_phrases::ExcludedSearchPhrasesHandler;
 pub use file_search::FileSearchHandler;
 pub use get_peer_address::GetPeerAddressHandler;
+pub use join_room::JoinRoomHandler;
+pub use leave_room::LeaveRoomHandler;
 pub use login::LoginHandler;
 pub use message_factory::MessageFactory;
 pub use message_user::MessageUser;
@@ -22,4 +29,7 @@ pub use parent_min_speed::ParentMinSpeedHandler;
 pub use parent_speed_ratio::ParentSpeedRatioHandler;
 pub use privileged_users::PrivilegedUsersHandler;
 pub use room_list::RoomListHandler;
+pub use say_chatroom::SayChatroomHandler;
+pub use user_joined_room::UserJoinedRoomHandler;
+pub use user_left_room::UserLeftRoomHandler;
 pub use wish_list_interval::WishListIntervalHandler;

soulseek-rs-lib/src/message/server/room_list.rs

@@ -1,6 +1,7 @@
 use crate::{
     actor::server_actor::ServerMessage,
     message::{Message, MessageHandler},
+    types::RoomInfo,
 };
 use std::sync::mpsc::Sender;
 
@@ -11,8 +12,101 @@ impl MessageHandler<ServerMessage> for RoomListHandler {
         64
     }
 
-    fn handle(&self, _message: &mut Message, _sender: Sender<ServerMessage>) {
-        // Room listing is not yet exposed to the client; this handler exists
-        // so the dispatcher can ack code 64 without logging an unknown message.
+    fn handle(&self, message: &mut Message, sender: Sender<ServerMessage>) {
+        let rooms = parse_room_list(message);
+        let _ = sender.send(ServerMessage::RoomListReceived(rooms));
+    }
+}
+
+/// Parse the public rooms out of a `RoomList` (code 64) message: a vector of
+/// room names followed by a vector of user counts. The remaining private-room
+/// sections are ignored. `message` must be positioned at the payload (the
+/// dispatcher sets pointer 8).
+#[must_use]
+pub fn parse_room_list(message: &mut Message) -> Vec<RoomInfo> {
+    let name_count = message.read_int32();
+    let mut names = Vec::new();
+    for _ in 0..name_count {
+        names.push(message.read_string());
+    }
+    let count_count = message.read_int32();
+    let mut counts = Vec::new();
+    for _ in 0..count_count {
+        counts.push(message.read_int32());
+    }
+    names
+        .into_iter()
+        .zip(counts)
+        .map(|(name, user_count)| RoomInfo { name, user_count })
+        .collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    /// Build a received message (8-byte header + payload) and position it the
+    /// way the dispatcher would.
+    fn framed(build: impl FnOnce(&mut Message)) -> Message {
+        let mut message = Message::new();
+        message.write_raw_bytes(vec![0u8; 8]);
+        build(&mut message);
+        message.set_pointer(8);
+        message
+    }
+
+    #[test]
+    fn parses_names_zipped_with_counts() {
+        let mut message = framed(|m| {
+            m.write_int32(2);
+            m.write_string("nicotine");
+            m.write_string("jazz");
+            m.write_int32(2);
+            m.write_int32(42);
+            m.write_int32(7);
+        });
+        let rooms = parse_room_list(&mut message);
+        assert_eq!(
+            rooms,
+            vec![
+                RoomInfo {
+                    name: "nicotine".to_string(),
+                    user_count: 42
+                },
+                RoomInfo {
+                    name: "jazz".to_string(),
+                    user_count: 7
+                },
+            ]
+        );
+    }
+
+    #[test]
+    fn empty_room_list_parses_to_empty() {
+        let mut message = framed(|m| {
+            m.write_int32(0);
+            m.write_int32(0);
+        });
+        assert!(parse_room_list(&mut message).is_empty());
+    }
+
+    #[test]
+    fn handler_forwards_parsed_rooms() {
+        let (tx, rx) = std::sync::mpsc::channel();
+        let mut message = framed(|m| {
+            m.write_int32(1);
+            m.write_string("room");
+            m.write_int32(1);
+            m.write_int32(5);
+        });
+        RoomListHandler.handle(&mut message, tx);
+        match rx.try_recv() {
+            Ok(ServerMessage::RoomListReceived(rooms)) => {
+                assert_eq!(rooms.len(), 1);
+                assert_eq!(rooms[0].name, "room");
+                assert_eq!(rooms[0].user_count, 5);
+            }
+            other => panic!("unexpected: {other:?}"),
+        }
     }
 }

soulseek-rs-lib/src/message/server/say_chatroom.rs

@@ -0,0 +1,54 @@
+use crate::{
+    actor::server_actor::ServerMessage,
+    message::{Message, MessageHandler},
+};
+use std::sync::mpsc::Sender;
+
+pub struct SayChatroomHandler;
+
+impl MessageHandler<ServerMessage> for SayChatroomHandler {
+    fn get_code(&self) -> u8 {
+        13
+    }
+
+    fn handle(&self, message: &mut Message, sender: Sender<ServerMessage>) {
+        let room = message.read_string();
+        let username = message.read_string();
+        let message_text = message.read_string();
+        let _ = sender.send(ServerMessage::RoomMessageReceived {
+            room,
+            username,
+            message: message_text,
+        });
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn forwards_room_message() {
+        let (tx, rx) = std::sync::mpsc::channel();
+        let mut message = Message::new();
+        message.write_raw_bytes(vec![0u8; 8]);
+        message.write_string("jazz");
+        message.write_string("alice");
+        message.write_string("hello everyone");
+        message.set_pointer(8);
+
+        SayChatroomHandler.handle(&mut message, tx);
+        match rx.try_recv() {
+            Ok(ServerMessage::RoomMessageReceived {
+                room,
+                username,
+                message,
+            }) => {
+                assert_eq!(room, "jazz");
+                assert_eq!(username, "alice");
+                assert_eq!(message, "hello everyone");
+            }
+            other => panic!("unexpected: {other:?}"),
+        }
+    }
+}

soulseek-rs-lib/src/message/server/user_joined_room.rs

@@ -0,0 +1,45 @@
+use crate::{
+    actor::server_actor::ServerMessage,
+    message::{Message, MessageHandler},
+};
+use std::sync::mpsc::Sender;
+
+pub struct UserJoinedRoomHandler;
+
+impl MessageHandler<ServerMessage> for UserJoinedRoomHandler {
+    fn get_code(&self) -> u8 {
+        16
+    }
+
+    fn handle(&self, message: &mut Message, sender: Sender<ServerMessage>) {
+        // UserJoinedRoom (code 16): room, username, then that user's stats,
+        // which we don't need. Reading the first two fields is enough.
+        let room = message.read_string();
+        let username = message.read_string();
+        let _ = sender.send(ServerMessage::RoomUserJoined { room, username });
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn forwards_user_joined() {
+        let (tx, rx) = std::sync::mpsc::channel();
+        let mut message = Message::new();
+        message.write_raw_bytes(vec![0u8; 8]);
+        message.write_string("jazz");
+        message.write_string("carol");
+        message.set_pointer(8);
+
+        UserJoinedRoomHandler.handle(&mut message, tx);
+        match rx.try_recv() {
+            Ok(ServerMessage::RoomUserJoined { room, username }) => {
+                assert_eq!(room, "jazz");
+                assert_eq!(username, "carol");
+            }
+            other => panic!("unexpected: {other:?}"),
+        }
+    }
+}

soulseek-rs-lib/src/message/server/user_left_room.rs

@@ -0,0 +1,43 @@
+use crate::{
+    actor::server_actor::ServerMessage,
+    message::{Message, MessageHandler},
+};
+use std::sync::mpsc::Sender;
+
+pub struct UserLeftRoomHandler;
+
+impl MessageHandler<ServerMessage> for UserLeftRoomHandler {
+    fn get_code(&self) -> u8 {
+        17
+    }
+
+    fn handle(&self, message: &mut Message, sender: Sender<ServerMessage>) {
+        let room = message.read_string();
+        let username = message.read_string();
+        let _ = sender.send(ServerMessage::RoomUserLeft { room, username });
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn forwards_user_left() {
+        let (tx, rx) = std::sync::mpsc::channel();
+        let mut message = Message::new();
+        message.write_raw_bytes(vec![0u8; 8]);
+        message.write_string("jazz");
+        message.write_string("carol");
+        message.set_pointer(8);
+
+        UserLeftRoomHandler.handle(&mut message, tx);
+        match rx.try_recv() {
+            Ok(ServerMessage::RoomUserLeft { room, username }) => {
+                assert_eq!(room, "jazz");
+                assert_eq!(username, "carol");
+            }
+            other => panic!("unexpected: {other:?}"),
+        }
+    }
+}

soulseek-rs-lib/src/types.rs

@@ -163,6 +163,36 @@ pub enum DownloadStatus {
     Failed(Option<String>),
     TimedOut,
 }
+
+/// A public chat room advertised by the server (`RoomList`, code 64).
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct RoomInfo {
+    pub name: String,
+    pub user_count: u32,
+}
+
+/// Something that happened in the chat-room subsystem, surfaced to the client
+/// so a UI can react to it. Drained via `Client::take_room_events`.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum RoomEvent {
+    /// The full list of public rooms (supersedes any previous snapshot).
+    List(Vec<RoomInfo>),
+    /// We successfully joined `room`; carries the current member list.
+    Joined { room: String, users: Vec<String> },
+    /// We left `room`.
+    Left { room: String },
+    /// `username` said `message` in `room`.
+    Message {
+        room: String,
+        username: String,
+        message: String,
+    },
+    /// `username` joined `room`.
+    UserJoined { room: String, username: String },
+    /// `username` left `room`.
+    UserLeft { room: String, username: String },
+}
+
 impl Transfer {
     pub fn new_from_message(message: &mut Message) -> Self {
         let direction = message.read_int32();