README.md

@@ -1,6 +1,6 @@
 ## curltastic
 
-A 1v1 async multiplayer 2D curling game for mobile browser.
+A multiplayer 2D curling game for mobile browser. Any number of clients can join a room, pick Red or Yellow freely, and throw when it is that team's turn (solo pass-and-play or remote opponents).
 
 - **Backend** — Rust, Axum, WebSocket, Rapier2D physics (server-authoritative, 120 Hz).
 - **Frontend** — TypeScript, Vite, Canvas2D, portrait-first touch UI.
@@ -21,22 +21,24 @@ A 1v1 async multiplayer 2D curling game for mobile browser.
    npm run dev
    # opens on 0.0.0.0:5173 by default
    ```
-4. Open two browser tabs to the same room URL, e.g.:
+4. Open one or more browser tabs to the same room URL, e.g.:
    ```
    http://localhost:5173/?room=DEMO1
    ```
-   The first tab waits; the second starts the match. Use the *Copy share link* button to invite an opponent.
+   Use the team dropdown in the top-right to switch between Red and Yellow — this enables local pass-and-play on one device. Use the *Copy share link* button to invite an opponent on another device.
 
 ### Mobile devices
 
-The frontend binds to `0.0.0.0` via `--host`. Find your machine's LAN IP and open `http://<ip>:5173/?room=CODE` on the phone. Both devices must be on the same Wi-Fi and able to reach the backend on port `3000`.
+The frontend binds to `0.0.0.0` via `--host`. Find your machine's LAN IP and open `http://<ip>:5173/?room=CODE` on the phone. Both devices must be on the same Wi-Fi and able to reach the backend on port `3000`. The default view is zoomed in on the house; drag the sheet vertically to scroll up to the hog line.
 
 ### Controls
 
-- Drag inside the house to place the broom (aim point).
-- Tap a weight `1`–`10`.
-- Tap **THROW**.
-- The server runs the physics and streams the trajectory; the frontend interpolates the animation.
+- When it is your team's turn, drag on the sheet to place the broom (aim point) — aim is not limited to the house.
+- When it is not your turn, drag to pan the ice (default framing shows the house with sidelines; pan up toward the hog line).
+- Use the team dropdown to choose which team's stone you are throwing; switch any time (including mid-end for solo play).
+- Use the left/right curl buttons and the weight/friction controls; friction is a local scalar.
+- Tap **THROW**. Anyone identifying as the turn team may throw.
+- The server runs physics for every stone and streams multi-stone paths; the client animates them on one clock so collisions move together.
 
 ### Architecture
 
@@ -52,8 +54,12 @@ With the backend and frontend dev server running:
 ```bash
 cd e2e
 npm install -g ws   # or npm install ws locally in the project
-node e2e_test.cjs   # room lifecycle, throw, trajectory, out-of-play removal
-node e2e_score.cjs  # stones remain in play and alternate turns
+node e2e_test.cjs              # room lifecycle, throw, trajectory
+node e2e_score.cjs             # alternate turns / stones in play
+node e2e_persistence.cjs       # multi-throw stone persistence
+node e2e_multi_client.cjs      # 3 clients share state (no room-full)
+node e2e_end_score.cjs         # full end → end_scored + next end
+node collision_trajectory_qa.cjs  # multi-stone trajectory on collision
 ```
 
 ### Limitations / known simplifications

backend/src/game.rs

@@ -12,8 +12,6 @@ pub enum GamePhase {
 }
 
 pub struct Game {
-    red: Option<Player>,
-    yellow: Option<Player>,
     phase: GamePhase,
     end: u8,
     scores: [i32; 2],
@@ -24,14 +22,18 @@ pub struct Game {
     stones_red: u8,
     stones_yellow: u8,
     last_end_scored: Option<(u8, i32, Option<Team>)>,
-    pub room_tx: Option<tokio::sync::broadcast::Sender<ServerMessage>>,
+}
+
+pub struct ThrowOutcome {
+    pub trajectory: Vec<StoneTrajectory>,
+    pub end_scored: Option<ServerMessage>,
+    pub state_message: ServerMessage,
+    pub game_over: Option<ServerMessage>,
 }
 
 impl Game {
     pub fn new() -> Self {
         Self {
-            red: None,
-            yellow: None,
             phase: GamePhase::Waiting,
             end: 1,
             scores: [0, 0],
@@ -42,81 +44,10 @@ impl Game {
             stones_red: STONES_PER_TEAM,
             stones_yellow: STONES_PER_TEAM,
             last_end_scored: None,
-            room_tx: None,
         }
     }
 
-    pub fn add_player(&mut self, id: String, preferred: Option<Team>) -> Option<Team> {
-        let team = match preferred {
-            Some(Team::Red) if self.red.is_none() => Some(Team::Red),
-            Some(Team::Yellow) if self.yellow.is_none() => Some(Team::Yellow),
-            Some(_) => {
-                // Preferred is taken; fall back to the other free team.
-                if self.red.is_none() {
-                    Some(Team::Red)
-                } else if self.yellow.is_none() {
-                    Some(Team::Yellow)
-                } else {
-                    None
-                }
-            }
-            None => {
-                // Legacy first-free logic.
-                if self.red.is_none() {
-                    Some(Team::Red)
-                } else if self.yellow.is_none() {
-                    Some(Team::Yellow)
-                } else {
-                    None
-                }
-            }
-        };
-
-        if let Some(t) = team {
-            let player = Player { id, team: t, connected: true };
-            match t {
-                Team::Red => self.red = Some(player),
-                Team::Yellow => self.yellow = Some(player),
-            }
-            Some(t)
-        } else {
-            None
-        }
-    }
-
-    pub fn remove_player(&mut self, id: &str) -> Option<Team> {
-        if let Some(ref p) = self.red {
-            if p.id == id {
-                self.red = None;
-                return Some(Team::Red);
-            }
-        }
-        if let Some(ref p) = self.yellow {
-            if p.id == id {
-                self.yellow = None;
-                return Some(Team::Yellow);
-            }
-        }
-        None
-    }
-
-    pub fn set_player_connected(&mut self, id: &str, connected: bool) {
-        if let Some(p) = self.red.as_mut().filter(|p| p.id == id) {
-            p.connected = connected;
-        }
-        if let Some(p) = self.yellow.as_mut().filter(|p| p.id == id) {
-            p.connected = connected;
-        }
-    }
-
-    pub fn can_start(&self) -> bool {
-        self.red.is_some() && self.yellow.is_some()
-    }
-
     pub fn start(&mut self) {
-        if !self.can_start() {
-            return;
-        }
         self.hammer = if rand::random() { Team::Red } else { Team::Yellow };
         self.turn_team = self.hammer.other();
         self.phase = GamePhase::Playing;
@@ -129,37 +60,24 @@ impl Game {
         self.active_stones.clear();
     }
 
-    pub fn current_player_id(&self) -> Option<&str> {
-        let p = match self.turn_team {
-            Team::Red => self.red.as_ref()?,
-            Team::Yellow => self.yellow.as_ref()?,
-        };
-        Some(&p.id)
-    }
-
-    pub fn current_team_for_player(&self, player_id: &str) -> Option<Team> {
-        if let Some(p) = self.red.as_ref() { if p.id == player_id { return Some(Team::Red); } }
-        if let Some(p) = self.yellow.as_ref() { if p.id == player_id { return Some(Team::Yellow); } }
-        None
-    }
-
-    pub fn handle_throw(&mut self, player_id: &str, broom_x: f32, broom_y: f32, weight: u8, curl: i8, friction: f32) -> Result<Vec<(f32, f32, f32)>, String> {
-        let current_id = self.current_player_id().ok_or("No current player")?;
-        if current_id != player_id {
+    pub fn handle_throw(
+        &mut self,
+        team: Team,
+        broom_x: f32,
+        broom_y: f32,
+        weight: u8,
+        curl: i8,
+        friction: f32,
+    ) -> Result<Vec<StoneTrajectory>, String> {
+        if self.turn_team != team {
             return Err("Not your turn".to_string());
         }
         if self.phase != GamePhase::Playing {
             return Err("Cannot throw now".to_string());
         }
-        let dx = broom_x - HOUSE_CENTER.0;
-        let dy = broom_y - HOUSE_CENTER.1;
-        let dist = (dx * dx + dy * dy).sqrt();
-        if dist > HOUSE_RADIUS {
-            return Err("Broom must be in the house".to_string());
-        }
 
         self.active_stones.clear();
-        let path = self.physics.throw(self.turn_team, broom_x, broom_y, weight, curl, friction)?;
+        let trajectory = self.physics.throw(self.turn_team, broom_x, broom_y, weight, curl, friction)?;
         self.active_stones = self.physics.current_stones();
         self.phase = GamePhase::Simulating;
 
@@ -168,7 +86,35 @@ impl Game {
             Team::Yellow => self.stones_yellow = self.stones_yellow.saturating_sub(1),
         }
 
-        Ok(path)
+        Ok(trajectory)
+    }
+
+    pub fn process_throw(
+        &mut self,
+        team: Team,
+        broom_x: f32,
+        broom_y: f32,
+        weight: u8,
+        curl: i8,
+        friction: f32,
+    ) -> Result<ThrowOutcome, String> {
+        let trajectory = self.handle_throw(team, broom_x, broom_y, weight, curl, friction)?;
+        self.finish_simulation();
+
+        let end_scored = self.take_last_end_scored();
+        let state_message = self.game_state_message();
+        let game_over = if self.phase == GamePhase::GameComplete {
+            Some(self.game_over_message())
+        } else {
+            None
+        };
+
+        Ok(ThrowOutcome {
+            trajectory,
+            end_scored,
+            state_message,
+            game_over,
+        })
     }
 
     pub fn finish_simulation(&mut self) {
@@ -179,10 +125,6 @@ impl Game {
         self.score_end_internal(false);
     }
 
-    pub fn score_end(&mut self) {
-        self.score_end_internal(true);
-    }
-
     fn score_end_internal(&mut self, force: bool) {
         let end_done = force || (self.stones_red == 0 && self.stones_yellow == 0);
         if !end_done {
@@ -220,7 +162,7 @@ impl Game {
                     Team::Red => 0,
                     Team::Yellow => 1,
                 };
-                self.scores[team_idx] += points as i32;
+                self.scores[team_idx] += points;
                 self.hammer = team.other();
             } else {
                 points = 0;
@@ -229,10 +171,10 @@ impl Game {
 
         self.last_end_scored = Some((self.end, points, scoring_team));
         self.phase = GamePhase::EndComplete;
-        self.end_ends_or_continue(points, scoring_team);
+        self.advance_end_or_finish();
     }
 
-    fn end_ends_or_continue(&mut self, _points: i32, _scoring_team: Option<Team>) {
+    fn advance_end_or_finish(&mut self) {
         let tied = self.scores[0] == self.scores[1];
         let after_regulation = self.end >= ENDS;
 
@@ -241,10 +183,6 @@ impl Game {
             return;
         }
 
-        if after_regulation && tied {
-            // Extra end
-        }
-
         self.end += 1;
         self.stones_red = STONES_PER_TEAM;
         self.stones_yellow = STONES_PER_TEAM;
@@ -255,10 +193,6 @@ impl Game {
         self.phase = GamePhase::Playing;
     }
 
-    pub fn phase(&self) -> GamePhase {
-        self.phase
-    }
-
     pub fn take_last_end_scored(&mut self) -> Option<ServerMessage> {
         let msg = self.last_end_scored.map(|(end, points, scoring_team)| {
             ServerMessage::EndScored { end, points, scoring_team }
@@ -300,24 +234,18 @@ impl Game {
     }
 }
 
-pub type RoomId = String;
-
 pub struct Room {
-    pub id: RoomId,
     pub game: Game,
     pub tx: tokio::sync::broadcast::Sender<ServerMessage>,
 }
 
 impl Room {
-    pub fn new(id: &str) -> Self {
+    pub fn new(_id: &str) -> Self {
         let (tx, _) = tokio::sync::broadcast::channel(256);
-        let mut room = Self {
-            id: id.to_string(),
+        Self {
             game: Game::new(),
             tx,
-        };
-        room.game.room_tx = Some(room.tx.clone());
-        room
+        }
     }
 }
 
@@ -326,29 +254,46 @@ mod tests {
     use super::*;
 
     #[test]
-    fn prefers_red_when_requested_and_free() {
-        let mut game = Game::new();
-        assert_eq!(game.add_player("p1".into(), Some(Team::Red)), Some(Team::Red));
+    fn starts_in_waiting_phase() {
+        let game = Game::new();
+        assert!(matches!(game.phase, GamePhase::Waiting));
     }
 
     #[test]
-    fn prefers_yellow_when_requested_and_free() {
+    fn starts_when_called() {
         let mut game = Game::new();
-        assert_eq!(game.add_player("p1".into(), Some(Team::Yellow)), Some(Team::Yellow));
+        game.start();
+        assert!(matches!(game.phase, GamePhase::Playing));
+        assert_eq!(game.end, 1);
+        assert_eq!(game.scores, [0, 0]);
     }
 
     #[test]
-    fn falls_back_when_preferred_taken() {
+    fn rejects_throw_for_wrong_team() {
         let mut game = Game::new();
-        assert_eq!(game.add_player("p1".into(), Some(Team::Red)), Some(Team::Red));
-        assert_eq!(game.add_player("p2".into(), Some(Team::Red)), Some(Team::Yellow));
+        game.start();
+        let turn = game.turn_team;
+        let wrong = turn.other();
+        let result = game.handle_throw(wrong, 0.5, 38.7, 7, 1, 1.0);
+        assert!(result.is_err());
     }
 
     #[test]
-    fn legacy_order_without_preference() {
+    fn accepts_throw_for_turn_team() {
         let mut game = Game::new();
-        assert_eq!(game.add_player("p1".into(), None), Some(Team::Red));
-        assert_eq!(game.add_player("p2".into(), None), Some(Team::Yellow));
-        assert_eq!(game.add_player("p3".into(), None), None);
+        game.start();
+        let turn = game.turn_team;
+        let result = game.handle_throw(turn, 0.5, 38.7, 7, 1, 1.0);
+        assert!(result.is_ok());
+    }
+
+    #[test]
+    fn accepts_broom_outside_house() {
+        let mut game = Game::new();
+        game.start();
+        let turn = game.turn_team;
+        // (0.0, 30.0) is well outside HOUSE_RADIUS of HOUSE_CENTER
+        let result = game.handle_throw(turn, 0.0, 30.0, 7, 1, 1.0);
+        assert!(result.is_ok(), "broom outside house should be allowed: {:?}", result.err());
     }
 }

backend/src/main.rs

@@ -13,30 +13,35 @@ use axum::extract::ws::{Message, Utf8Bytes, WebSocket};
 use futures_util::{sink::SinkExt, stream::StreamExt};
 use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
-use std::sync::{Arc, Mutex};
-use tokio::sync::Mutex as TokioMutex;
+use std::sync::Arc;
+use tokio::sync::Mutex;
 use tracing::{info, warn};
 use uuid::Uuid;
 
-use crate::game::{GamePhase, Room};
+use crate::game::{Room, ThrowOutcome};
 use crate::protocol::*;
 
+type WsSender = futures_util::stream::SplitSink<WebSocket, Message>;
+type WsReceiver = futures_util::stream::SplitStream<WebSocket>;
+
 #[derive(Clone)]
 struct AppState {
-    rooms: Arc<Mutex<HashMap<String, Arc<TokioMutex<Room>>>>>,
+    rooms: Arc<Mutex<HashMap<String, Arc<Mutex<Room>>>>>,
 }
 
 impl AppState {
     fn new() -> Self {
-        Self { rooms: Arc::new(Mutex::new(HashMap::new())) }
+        Self {
+            rooms: Arc::new(Mutex::new(HashMap::new())),
+        }
     }
 
-    fn get_or_create_room(&self, room_id: &str) -> Arc<TokioMutex<Room>> {
-        let mut rooms = self.rooms.lock().unwrap();
+    async fn get_or_create_room(&self, room_id: &str) -> Arc<Mutex<Room>> {
+        let mut rooms = self.rooms.lock().await;
         if let Some(room) = rooms.get(room_id).cloned() {
             return room;
         }
-        let room = Arc::new(TokioMutex::new(Room::new(room_id)));
+        let room = Arc::new(Mutex::new(Room::new(room_id)));
         rooms.insert(room_id.to_string(), room.clone());
         room
     }
@@ -45,7 +50,6 @@ impl AppState {
 #[derive(Deserialize)]
 struct RoomQuery {
     room: String,
-    team: Option<Team>,
 }
 
 #[derive(Serialize)]
@@ -81,7 +85,7 @@ async fn health() -> impl IntoResponse {
 
 async fn new_room(State(state): State<Arc<AppState>>) -> impl IntoResponse {
     let room_id = generate_room_code();
-    state.get_or_create_room(&room_id);
+    state.get_or_create_room(&room_id).await;
     (StatusCode::OK, axum::Json(NewRoomResponse { room: room_id }))
 }
 
@@ -90,53 +94,50 @@ async fn ws_handler(
     Query(query): Query<RoomQuery>,
     State(state): State<Arc<AppState>>,
 ) -> impl IntoResponse {
-    ws.on_upgrade(move |socket| handle_socket(socket, state, query.room, query.team))
+    ws.on_upgrade(move |socket| handle_socket(socket, state, query.room))
 }
 
-async fn handle_socket(socket: WebSocket, state: Arc<AppState>, room_id: String, preferred_team: Option<Team>) {
-    let room_arc = state.get_or_create_room(&room_id);
-    let player_id = Uuid::new_v4().to_string();
-    let player_id_for_recv = player_id.clone();
+async fn handle_socket(
+    socket: WebSocket,
+    state: Arc<AppState>,
+    room_id: String,
+) {
+    let room = state.get_or_create_room(&room_id).await;
+    let (mut sender, receiver) = socket.split();
 
-    let (mut sender, mut receiver) = socket.split();
-
-    // Reject room-full before subscribing so the error goes only to the joining socket.
     {
-        let room = room_arc.lock().await;
-        if room.game.can_start() {
-            let err = serde_json::to_string(&ServerMessage::Error {
-                message: "Room is full".to_string(),
-            }).unwrap();
-            let _ = sender.send(Message::Text(Utf8Bytes::from(err))).await;
+        let mut room_guard = room.lock().await;
+        if matches!(room_guard.game.game_state_message(), ServerMessage::GameState { phase: Phase::Waiting, .. }) {
+            room_guard.game.start();
+        }
+    }
+
+    let joined = serde_json::to_string(&ServerMessage::Joined {
+        room: room_id.clone(),
+    })
+    .unwrap();
+    if sender.send(Message::Text(Utf8Bytes::from(joined))).await.is_err() {
         return;
     }
+
+    let tx = { room.lock().await.tx.clone() };
+
+    let send_task = spawn_forwarder(sender, tx.subscribe());
+    broadcast_room_state(&room, &tx).await;
+
+    let recv_task = spawn_message_handler(room.clone(), tx, receiver);
+
+    tokio::select! {
+        _ = send_task => {}
+        _ = recv_task => {}
+    }
 }
 
-    // Add the player to the room and tell only this socket its assigned team.
-    let team = {
-        let mut room = room_arc.lock().await;
-        let team = room.game.add_player(player_id.clone(), preferred_team)
-            .unwrap_or(Team::Red);
-        if room.game.can_start() {
-            room.game.start();
-        }
-        team
-    };
-
-    let joined_msg = serde_json::to_string(&ServerMessage::Joined {
-        room: room_id.clone(),
-        team,
-    }).unwrap();
-    let _ = sender.send(Message::Text(Utf8Bytes::from(joined_msg))).await;
-
-    // Subscribe to broadcast and spawn the forwarding task.
-    let tx = {
-        let room = room_arc.lock().await;
-        room.tx.clone()
-    };
-    let mut rx = tx.subscribe();
-
-    let send_task = tokio::spawn(async move {
+fn spawn_forwarder(
+    mut sender: WsSender,
+    mut rx: tokio::sync::broadcast::Receiver<ServerMessage>,
+) -> tokio::task::JoinHandle<()> {
+    tokio::spawn(async move {
         loop {
             match rx.recv().await {
                 Ok(msg) => {
@@ -151,49 +152,51 @@ async fn handle_socket(socket: WebSocket, state: Arc<AppState>, room_id: String,
                 Err(_) => break,
             }
         }
-    });
-
-    // Broadcast waiting/game state to everyone in the room.
-    {
-        let room = room_arc.lock().await;
-        if room.game.can_start() {
-            let state_msg = room.game.game_state_message();
-            let _ = room.tx.send(state_msg);
-        } else {
-            let _ = room.tx.send(ServerMessage::Waiting { message: "Waiting for other player".to_string() });
-        }
+    })
 }
 
-    let recv_room = room_arc.clone();
-    let recv_id = player_id_for_recv;
-    let recv_task = tokio::spawn(async move {
+async fn broadcast_room_state(
+    room: &Arc<Mutex<Room>>,
+    tx: &tokio::sync::broadcast::Sender<ServerMessage>,
+) {
+    let room_guard = room.lock().await;
+    let _ = tx.send(room_guard.game.game_state_message());
+}
+
+fn spawn_message_handler(
+    room: Arc<Mutex<Room>>,
+    tx: tokio::sync::broadcast::Sender<ServerMessage>,
+    mut receiver: WsReceiver,
+) -> tokio::task::JoinHandle<()> {
+    tokio::spawn(async move {
         while let Some(Ok(msg)) = receiver.next().await {
-            let Message::Text(text) = msg else { continue; };
+            let Message::Text(text) = msg else { continue };
             let text_ref = text.as_str();
             let parsed: Result<ClientMessage, _> = serde_json::from_str(text_ref);
             match parsed {
-                Ok(ClientMessage::Throw { broom_x, broom_y, weight, curl, friction }) => {
-                    let room = recv_room.clone();
-                    let mut room = room.lock().await;
-                    if room.game.current_team_for_player(&recv_id) != Some(team) {
-                        let _ = room.tx.send(ServerMessage::Error { message: "Not your turn".to_string() });
-                        continue;
+                Ok(ClientMessage::Throw { team, broom_x, broom_y, weight, curl, friction }) => {
+                    let mut room_guard = room.lock().await;
+                    match room_guard
+                        .game
+                        .process_throw(team, broom_x, broom_y, weight, curl, friction)
+                    {
+                        Ok(ThrowOutcome {
+                            trajectory,
+                            end_scored,
+                            state_message,
+                            game_over,
+                        }) => {
+                            let _ = tx.send(ServerMessage::Trajectory { paths: trajectory });
+                            if let Some(scored) = end_scored {
+                                let _ = tx.send(scored);
                             }
-                    match room.game.handle_throw(&recv_id, broom_x, broom_y, weight, curl, friction) {
-                        Ok(path) => {
-                            room.tx.send(ServerMessage::Trajectory { path }).ok();
-                            room.game.finish_simulation();
-                            if let Some(scored) = room.game.take_last_end_scored() {
-                                room.tx.send(scored).ok();
-                            }
-                            let after = room.game.game_state_message();
-                            room.tx.send(after).ok();
-                            if room.game.phase() == GamePhase::GameComplete {
-                                room.tx.send(room.game.game_over_message()).ok();
+                            let _ = tx.send(state_message);
+                            if let Some(over) = game_over {
+                                let _ = tx.send(over);
                             }
                         }
                         Err(e) => {
-                            room.tx.send(ServerMessage::Error { message: e }).ok();
+                            let _ = tx.send(ServerMessage::Error { message: e });
                         }
                     }
                 }
@@ -202,16 +205,5 @@ async fn handle_socket(socket: WebSocket, state: Arc<AppState>, room_id: String,
                 }
             }
         }
-    });
-
-    tokio::select! {
-        _ = send_task => {}
-        _ = recv_task => {}
-    }
-
-    // On disconnect, free the team slot so refreshes and new tabs can rejoin.
-    {
-        let mut room = room_arc.lock().await;
-        let _ = room.game.remove_player(&player_id);
-    }
+    })
 }

backend/src/physics.rs

@@ -107,7 +107,7 @@ impl PhysicsWorld {
         weight: u8,
         curl: i8,
         friction: f32,
-    ) -> Result<Vec<(f32, f32, f32)>, String> {
+    ) -> Result<Vec<StoneTrajectory>, String> {
         let weight = weight.clamp(1, 10) as f32;
         let t = (weight - 1.0) / 9.0;
         let speed = MIN_SPEED + t * (MAX_SPEED - MIN_SPEED);
@@ -132,7 +132,7 @@ impl PhysicsWorld {
         vy: f32,
         curl_sign: i8,
         damping_mult: f32,
-    ) -> Result<Vec<(f32, f32, f32)>, String> {
+    ) -> Result<Vec<StoneTrajectory>, String> {
         let id = self.next_stone_id;
         self.next_stone_id += 1;
 
@@ -161,15 +161,31 @@ impl PhysicsWorld {
         self.simulate_until_rest(id)
     }
 
-    fn simulate_until_rest(&mut self, thrown_id: u32) -> Result<Vec<(f32, f32, f32)>, String> {
-        let mut path: Vec<(f32, f32, f32)> = Vec::new();
+    fn simulate_until_rest(&mut self, thrown_id: u32) -> Result<Vec<StoneTrajectory>, String> {
+        // All paths share the thrown stone's release instant as t=0. This keeps the
+        // frontend's existing trajectory helpers (which expect the thrown stone to
+        // start at x=0, y=HACK_Y with t=0) working unchanged while also giving every
+        // other stone a consistent timeline.
         let sample_step = 1.0 / SAMPLE_RATE_HZ as f32;
         let mut sample_accum: f32 = 0.0;
         let mut time: f32 = 0.0;
 
-        if let Some((_, h, _, _)) = self.stone_handles.iter().find(|(id, _, _, _)| *id == thrown_id) {
-            let body = &self.bodies[*h];
-            path.push((body.translation().x, body.translation().y, time));
+        // Pre-allocate a path buffer for every stone currently in the world.
+        let mut paths: Vec<(u32, RigidBodyHandle, Vec<(f32, f32, f32)>)> = self
+            .stone_handles
+            .iter()
+            .map(|(id, handle, _, _)| (*id, *handle, Vec::new()))
+            .collect();
+
+        // Record the initial sample at t=0 for every stone.
+        for (id, handle, path) in &mut paths {
+            if let Some(body) = self.bodies.get(*handle) {
+                let pos = body.translation();
+                path.push((pos.x, pos.y, time));
+            } else {
+                // Body missing for an tracked stone; this should not happen.
+                return Err(format!("stone {} has no rigid body", id));
+            }
         }
 
         loop {
@@ -180,9 +196,11 @@ impl PhysicsWorld {
 
             if sample_accum >= sample_step {
                 sample_accum -= sample_step;
-                if let Some((_, h, _, _)) = self.stone_handles.iter().find(|(id, _, _, _)| *id == thrown_id) {
-                    let body = &self.bodies[*h];
-                    path.push((body.translation().x, body.translation().y, time));
+                for (_, handle, path) in &mut paths {
+                    if let Some(body) = self.bodies.get(*handle) {
+                        let pos = body.translation();
+                        path.push((pos.x, pos.y, time));
+                    }
                 }
             }
 
@@ -193,7 +211,27 @@ impl PhysicsWorld {
 
         self.prune_out_of_play();
 
-        Ok(path)
+        // The thrown stone is released at (0.0, HACK_Y). Shift every path in time so
+        // that t=0 corresponds to that release instant. Because we already started
+        // sampling at the release instant, the first sample time is 0.0 and no shift
+        // is required; this comment documents the invariant.
+        let thrown_first_t = paths
+            .iter()
+            .find(|(id, _, _)| *id == thrown_id)
+            .and_then(|(_, _, path)| path.first().map(|(_, _, t)| *t))
+            .unwrap_or(0.0);
+
+        Ok(paths
+            .into_iter()
+            .map(|(id, _, mut path)| {
+                if thrown_first_t != 0.0 {
+                    for (_, _, t) in &mut path {
+                        *t -= thrown_first_t;
+                    }
+                }
+                StoneTrajectory { stone_id: id, path }
+            })
+            .collect())
     }
 
     // Rotate each stone's velocity slightly based on its selected curl direction.
@@ -377,4 +415,70 @@ mod tests {
         let stones = world.current_stones();
         assert!(stones.is_empty(), "stones short of the hog line should be pruned");
     }
+
+    #[test]
+    fn collision_records_trajectories_for_both_stones() {
+        // Place a stationary stone on the center line and throw a second stone
+        // straight at it so they collide. Both stones must have sampled paths.
+        let mut world = PhysicsWorld::new();
+
+        // First stone: place it far enough up-sheet to stay in play after impact.
+        world
+            .throw(Team::Red, 0.0, HOUSE_CENTER.1, 7, 0, 1.0)
+            .unwrap();
+        let first_id = world.next_stone_id - 1;
+
+        // Second stone: aimed directly at the first stone's final position.
+        let target_y = final_y(&world, first_id);
+        let target_x = final_x(&world, first_id);
+        world
+            .throw(Team::Yellow, target_x, target_y, 10, 0, 1.0)
+            .unwrap();
+        let second_id = world.next_stone_id - 1;
+
+        // Re-run the collision throw and capture trajectories.
+        let mut world = PhysicsWorld::new();
+        world
+            .throw(Team::Red, 0.0, HOUSE_CENTER.1, 7, 0, 1.0)
+            .unwrap();
+        let first_id = world.next_stone_id - 1;
+        let target_y = final_y(&world, first_id);
+        let target_x = final_x(&world, first_id);
+        let trajectories = world
+            .throw(Team::Yellow, target_x, target_y, 10, 0, 1.0)
+            .unwrap();
+
+        let by_id: std::collections::HashMap<u32, Vec<(f32, f32, f32)>> = trajectories
+            .into_iter()
+            .map(|st| (st.stone_id, st.path))
+            .collect();
+
+        assert!(
+            by_id.contains_key(&first_id),
+            "trajectories should contain the first stone (id={})",
+            first_id
+        );
+        assert!(
+            by_id.contains_key(&second_id),
+            "trajectories should contain the thrown stone (id={})",
+            second_id
+        );
+
+        let first_path = by_id.get(&first_id).unwrap();
+        let second_path = by_id.get(&second_id).unwrap();
+        assert!(
+            first_path.len() > 1,
+            "first stone path should have multiple samples, got {}",
+            first_path.len()
+        );
+        assert!(
+            second_path.len() > 1,
+            "thrown stone path should have multiple samples, got {}",
+            second_path.len()
+        );
+
+        // Both paths should share the same t=0 reference (the thrown stone's release).
+        assert_eq!(first_path[0].2, 0.0, "first stone path should start at t=0");
+        assert_eq!(second_path[0].2, 0.0, "thrown stone path should start at t=0");
+    }
 }

backend/src/protocol.rs

@@ -4,6 +4,7 @@ use std::fmt;
 pub const TICK_RATE_HZ: u16 = 120;
 pub const SAMPLE_RATE_HZ: u16 = 40;
 pub const PHYSICS_DT: f32 = 1.0 / TICK_RATE_HZ as f32;
+pub const FEET_TO_METERS: f32 = 0.3048;
 
 pub const STONES_PER_TEAM: u8 = 8;
 pub const ENDS: u8 = 10;
@@ -12,11 +13,7 @@ pub const ENDS: u8 = 10;
 pub const SHEET_WIDTH: f32 = 5.0;
 pub const SHEET_LENGTH: f32 = 45.0;
 pub const HOUSE_CENTER: (f32, f32) = (0.0, 38.5);
-pub const HOUSE_RADIUS: f32 = 1.83; // 12 ft
-pub const BUTTON_RADIUS: f32 = 0.1524; // 0.5 ft
-pub const FOUR_FT_RADIUS: f32 = 0.6096;
-pub const EIGHT_FT_RADIUS: f32 = 1.2192;
-pub const TWELVE_FT_RADIUS: f32 = 1.8288;
+pub const HOUSE_RADIUS: f32 = 6.0 * FEET_TO_METERS; // 12 ft diameter → 6 ft radius
 pub const HOG_LINE_Y: f32 = 21.0;
 pub const BACK_LINE_Y: f32 = 42.0;
 pub const HACK_Y: f32 = 2.0;
@@ -59,6 +56,7 @@ impl fmt::Display for Team {
 #[serde(tag = "type", rename_all = "snake_case")]
 pub enum ClientMessage {
     Throw {
+        team: Team,
         broom_x: f32,
         broom_y: f32,
         weight: u8,
@@ -75,7 +73,7 @@ fn default_friction() -> f32 { 1.0 }
 #[derive(Debug, Clone, Serialize, Deserialize)]
 #[serde(tag = "type", rename_all = "snake_case")]
 pub enum ServerMessage {
-    Joined { room: String, team: Team },
+    Joined { room: String },
     Waiting { message: String },
     GameState {
         end: u8,
@@ -86,7 +84,7 @@ pub enum ServerMessage {
         phase: Phase,
     },
     Trajectory {
-        path: Vec<(f32, f32, f32)>,
+        paths: Vec<StoneTrajectory>,
     },
     EndScored { end: u8, points: i32, scoring_team: Option<Team> },
     GameOver {
@@ -108,6 +106,12 @@ pub enum Phase {
     GameComplete,
 }
 
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct StoneTrajectory {
+    pub stone_id: u32,
+    pub path: Vec<(f32, f32, f32)>,
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct StoneState {
     pub id: u32,
@@ -117,10 +121,3 @@ pub struct StoneState {
     pub rotation: f32,
     pub active: bool,
 }
-
-#[derive(Debug, Clone, Default, Serialize, Deserialize)]
-pub struct Player {
-    pub id: String,
-    pub team: Team,
-    pub connected: bool,
-}

e2e/collision_trajectory_qa.cjs

@@ -0,0 +1,72 @@
+const WebSocket = require('ws')
+const room = 'COLQA' + Math.floor(Math.random() * 1000)
+const url = 'ws://127.0.0.1:3000/ws?room=' + room
+
+function connect() {
+  return new Promise((resolve, reject) => {
+    const ws = new WebSocket(url)
+    const messages = []
+    ws.on('open', () => resolve({ ws, messages }))
+    ws.on('message', (data) => messages.push(JSON.parse(data.toString())))
+    ws.on('error', reject)
+  })
+}
+
+function waitFor(messages, pred, timeout = 10000) {
+  const start = Date.now()
+  return new Promise((resolve, reject) => {
+    const check = () => {
+      if (pred()) return resolve(undefined)
+      if (Date.now() - start > timeout) return reject(new Error('timeout'))
+      setTimeout(check, 50)
+    }
+    check()
+  })
+}
+
+;(async () => {
+  const c = await connect()
+  await waitFor(c.messages, () => {
+    const last = c.messages[c.messages.length - 1]
+    return last && last.type === 'game_state' && last.phase === 'playing'
+  })
+
+  // First throw: weight 7 so it stays in house.
+  let state = c.messages[c.messages.length - 1]
+  c.ws.send(JSON.stringify({ type: 'throw', team: state.turn_team, broom_x: 0.0, broom_y: 38.5, weight: 7, curl: 0, friction: 1.0 }))
+  await waitFor(c.messages, () => c.messages.filter(m => m.type === 'game_state').length > 1)
+  state = c.messages[c.messages.length - 1]
+  console.log('After first throw stones:', state.stones.map(s => ({ id: s.id, x: s.x, y: s.y })))
+  if (state.stones.length !== 1) throw new Error('expected first stone in play')
+
+  const trajCountBefore = c.messages.filter(m => m.type === 'trajectory').length
+  console.log('trajectory count before second throw:', trajCountBefore)
+
+  // Second throw aimed slightly off-center so it hits the first stone.
+  c.ws.send(JSON.stringify({ type: 'throw', team: state.turn_team, broom_x: 0.25, broom_y: 38.5, weight: 7, curl: 0, friction: 1.0 }))
+  await waitFor(c.messages, () => c.messages.filter(m => m.type === 'trajectory').length > trajCountBefore)
+
+  const traj = c.messages.filter(m => m.type === 'trajectory').pop()
+  console.log('Trajectory paths count:', traj.paths.length)
+  for (const p of traj.paths) {
+    console.log('stone_id', p.stone_id, 'path length', p.path.length, 'first', p.path[0], 'last', p.path[p.path.length - 1])
+  }
+
+  const ids = traj.paths.map(p => p.stone_id).sort((a, b) => a - b)
+  if (ids.length !== 2 || ids[0] !== 1 || ids[1] !== 2) throw new Error('expected both stone ids in trajectory, got ' + JSON.stringify(ids))
+  for (const p of traj.paths) {
+    if (p.path.length < 5) throw new Error('path too short for stone ' + p.stone_id)
+  }
+
+  // Verify the first stone actually moved because of collision.
+  const stone1Path = traj.paths.find(p => p.stone_id === 1).path
+  const first = stone1Path[0]
+  const last = stone1Path[stone1Path.length - 1]
+  const dist = Math.sqrt((last[0]-first[0])**2 + (last[1]-first[1])**2)
+  console.log('stone1 moved', dist, 'm')
+  if (dist < 0.05) throw new Error('expected first stone to move after collision')
+
+  console.log('COLLISION TRAJECTORY QA PASSED')
+  c.ws.close()
+  process.exit(0)
+})().catch(e => { console.error(e); process.exit(1) })

e2e/e2e_end_score.cjs

@@ -9,7 +9,7 @@ function connect(name, room) {
     ws.on('message', (data) => {
       const msg = JSON.parse(data.toString())
       messages.push(msg)
-      if (msg.type === 'joined') resolve({ ws, messages, team: msg.team })
+      if (msg.type === 'joined') resolve({ ws, messages })
     })
     ws.on('error', reject)
   })
@@ -47,9 +47,8 @@ function waitFor(messages, pred, timeout = 30000) {
     }, 5000)
     const turn = getTurn()
     if (!turn) throw new Error('no turn')
-    const thrower = turn === p1.team ? p1 : p2
     const broomX = (Math.random() - 0.5) * 0.6
-    thrower.ws.send(JSON.stringify({ type: 'throw', broom_x: broomX, broom_y: 38.7, weight: 9, curl: 1, friction: 1.0 }))
+    p1.ws.send(JSON.stringify({ type: 'throw', team: turn, broom_x: broomX, broom_y: 38.7, weight: 9, curl: 1, friction: 1.0 }))
     const prevStateCount = p1.messages.filter(m => m.type === 'game_state').length
     await waitFor(p1.messages, () => p1.messages.filter(m => m.type === 'game_state').length > prevStateCount, 15000)
   }

e2e/e2e_multi_client.cjs

@@ -0,0 +1,75 @@
+const WebSocket = require('ws')
+
+const room = 'MULTI' + Math.floor(Math.random() * 1000)
+const base = 'ws://127.0.0.1:3000/ws?room=' + room
+
+function connect(name) {
+  return new Promise((resolve, reject) => {
+    const ws = new WebSocket(base)
+    const messages = []
+    ws.on('message', (data) => {
+      const msg = JSON.parse(data.toString())
+      messages.push(msg)
+      console.log(`[${name}]`, msg.type)
+      if (msg.type === 'joined') {
+        resolve({ ws, messages })
+      }
+    })
+    ws.on('open', () => console.log(`[${name}] open`))
+    ws.on('error', (e) => { console.error(`[${name}] error`, e.message); reject(e) })
+    ws.on('close', (code) => console.log(`[${name}] close`, code))
+  })
+}
+
+function waitFor(client, pred, timeout = 10000) {
+  const start = Date.now()
+  return new Promise((resolve, reject) => {
+    const check = () => {
+      if (pred(client.messages)) return resolve(undefined)
+      if (Date.now() - start > timeout) return reject(new Error('timeout'))
+      setTimeout(check, 50)
+    }
+    check()
+  })
+}
+
+;(async () => {
+  // 3 clients join the same room
+  const p1 = await connect('p1')
+  const p2 = await connect('p2')
+  const p3 = await connect('p3')
+
+  // All 3 receive game_state after join
+  await waitFor(p1, msgs => msgs.some(m => m.type === 'game_state'), 5000)
+  await waitFor(p2, msgs => msgs.some(m => m.type === 'game_state'), 5000)
+  await waitFor(p3, msgs => msgs.some(m => m.type === 'game_state'), 5000)
+  console.log('All 3 clients received game_state')
+
+  // p1 throws for the current turn_team
+  const state = p1.messages.find(m => m.type === 'game_state')
+  const turn = state.turn_team
+  console.log(`p1 throwing for team ${turn}`)
+  p1.ws.send(JSON.stringify({ type: 'throw', team: turn, broom_x: 0.5, broom_y: 39, weight: 7, curl: 1, friction: 1.0 }))
+
+  // All 3 clients eventually see trajectory or updated game_state
+  await waitFor(p1, msgs => msgs.some(m => m.type === 'trajectory'), 15000)
+  await waitFor(p2, msgs => msgs.some(m => m.type === 'trajectory'), 15000)
+  await waitFor(p3, msgs => msgs.some(m => m.type === 'trajectory'), 15000)
+  console.log('All 3 clients received trajectory')
+
+  // All 3 see an updated game_state after the throw
+  const lastIdx = p1.messages.length - 1
+  await waitFor(p1, msgs => msgs.slice(-1)[0]?.type === 'game_state', 15000)
+  await waitFor(p2, msgs => msgs.slice(-1)[0]?.type === 'game_state', 15000)
+  await waitFor(p3, msgs => msgs.slice(-1)[0]?.type === 'game_state', 15000)
+  console.log('All 3 clients received updated game_state after throw')
+
+  console.log('Multi-client observer test passed')
+  p1.ws.close()
+  p2.ws.close()
+  p3.ws.close()
+  process.exit(0)
+})().catch(err => {
+  console.error(err)
+  process.exit(1)
+})

e2e/e2e_persistence.cjs

@@ -12,7 +12,7 @@ function connect(name) {
       messages.push(msg)
       console.log(`[${name}]`, msg.type, msg.type === 'game_state' ? ` turn=${msg.turn_team} stones=${msg.stones.length}` : '')
       if (msg.type === 'joined') {
-        resolve({ ws, messages, team: msg.team })
+        resolve({ ws, messages })
       }
     })
     ws.on('open', () => console.log(`[${name}] open`))
@@ -38,27 +38,23 @@ function latestState(messages) {
 
 ;(async () => {
   const p1 = await connect('p1')
-  await waitFor(() => p1.messages.some(m => m.type === 'waiting'))
-  const p2 = await connect('p2')
-  await waitFor(() => p2.messages.some(m => m.type === 'game_state'))
+  await waitFor(() => p1.messages.some(m => m.type === 'game_state'))
 
   // Determine the current player and throw two stones in the same end.
   let state = latestState(p1.messages)
   console.log('Initial state', state)
 
-  // First throw: yellow aims slightly left of center.
+  // First throw: current turn team.
   let turn = state.turn_team
-  let turnPlayer = turn === p1.team ? p1 : p2
-  turnPlayer.ws.send(JSON.stringify({ type: 'throw', broom_x: -0.3, broom_y: 39, weight: 7, curl: 1, friction: 1.0 }))
+  p1.ws.send(JSON.stringify({ type: 'throw', team: turn, broom_x: -0.3, broom_y: 39, weight: 7, curl: 1, friction: 1.0 }))
   await waitFor(() => latestState(p1.messages)?.stones?.length === 1, 15000)
 
   state = latestState(p1.messages)
   console.log('After first throw:', state)
 
-  // Second throw: red aims slightly right of center.
+  // Second throw: other team.
   turn = state.turn_team
-  turnPlayer = turn === p1.team ? p1 : p2
-  turnPlayer.ws.send(JSON.stringify({ type: 'throw', broom_x: 0.3, broom_y: 39, weight: 7, curl: -1, friction: 1.0 }))
+  p1.ws.send(JSON.stringify({ type: 'throw', team: turn, broom_x: 0.3, broom_y: 39, weight: 7, curl: -1, friction: 1.0 }))
   await waitFor(() => latestState(p1.messages)?.stones?.length === 2, 15000)
 
   state = latestState(p1.messages)
@@ -77,7 +73,6 @@ function latestState(messages) {
 
   console.log('PERSISTENCE E2E PASSED')
   p1.ws.close()
-  p2.ws.close()
   process.exit(0)
 })().catch(err => {
   console.error(err)

e2e/e2e_room_full.cjs

@@ -1,47 +0,0 @@
-const WebSocket = require('ws')
-
-const base = (room) => `ws://127.0.0.1:3000/ws?room=${room}`
-
-function connect(name, room) {
-  return new Promise((resolve, reject) => {
-    const ws = new WebSocket(base(room))
-    const messages = []
-    ws.on('open', () => resolve({ ws, messages }))
-    ws.on('message', (data) => messages.push(JSON.parse(data.toString())))
-    ws.on('error', reject)
-  })
-}
-
-function waitFor(messages, pred, timeout = 10000) {
-  const start = Date.now()
-  return new Promise((resolve, reject) => {
-    const check = () => {
-      if (pred()) return resolve(undefined)
-      if (Date.now() - start > timeout) return reject(new Error('timeout'))
-      setTimeout(check, 50)
-    }
-    check()
-  })
-}
-
-;(async () => {
-  const room = 'ROOMFULL' + Math.floor(Math.random() * 1000)
-  const p1 = await connect('p1', room)
-  const p2 = await connect('p2', room)
-  await waitFor(p1.messages, () => p1.messages.some(m => m.type === 'game_state'), 5000)
-  const p3 = await connect('p3', room)
-  await waitFor(p3.messages, () => p3.messages.some(m => m.type === 'error'), 2000)
-  const p3error = p3.messages.some(m => m.type === 'error' && m.message.includes('Room is full'))
-  const p1error = p1.messages.some(m => m.type === 'error' && m.message.includes('Room is full'))
-  const p2error = p2.messages.some(m => m.type === 'error' && m.message.includes('Room is full'))
-  console.log({ p3error, p1error, p2error })
-  if (!p3error) throw new Error('p3 should get room full error')
-  if (p1error || p2error) throw new Error('existing players should not see room-full error')
-  p1.ws.close()
-  p2.ws.close()
-  p3.ws.close()
-  process.exit(0)
-})().catch((e) => {
-  console.error(e)
-  process.exit(1)
-})

e2e/e2e_score.cjs

@@ -9,7 +9,7 @@ function connect(name) {
     ws.on('message', (data) => {
       const msg = JSON.parse(data.toString())
       messages.push(msg)
-      if (msg.type === 'joined') resolve({ ws, messages, team: msg.team })
+      if (msg.type === 'joined') resolve({ ws, messages })
     })
     ws.on('error', reject)
   })
@@ -29,26 +29,24 @@ function waitFor(condFn, timeout = 5000) {
 
 ;(async () => {
   const p1 = await connect('p1')
-  const p2 = await connect('p2')
   await waitFor(() => p1.messages.some(m => m.type === 'game_state'))
   let state = p1.messages.find(m => m.type === 'game_state')
   console.log('start turn', state.turn_team, 'hammer', state.hammer)
 
-  const thrower1 = state.turn_team === p1.team ? p1 : p2
-  thrower1.ws.send(JSON.stringify({ type: 'throw', broom_x: 0.2, broom_y: 38.7, weight: 9, curl: 1, friction: 1.0 }))
+  const thrower1 = state.turn_team
+  p1.ws.send(JSON.stringify({ type: 'throw', team: thrower1, broom_x: 0.2, broom_y: 38.7, weight: 9, curl: 1, friction: 1.0 }))
   await waitFor(() => p1.messages.some(m => m.type === 'trajectory'), 15000)
   await waitFor(() => p1.messages.slice(-1)[0]?.type === 'game_state', 15000)
   await new Promise(r => setTimeout(r, 500))
   state = p1.messages.slice(-1)[0]
   console.log('After first throw:', state)
-  const thrower2 = state.turn_team === p1.team ? p1 : p2
-  thrower2.ws.send(JSON.stringify({ type: 'throw', broom_x: -0.1, broom_y: 38.8, weight: 9, curl: 1, friction: 1.0 }))
+  const thrower2 = state.turn_team
+  p1.ws.send(JSON.stringify({ type: 'throw', team: thrower2, broom_x: -0.1, broom_y: 38.8, weight: 9, curl: 1, friction: 1.0 }))
   await waitFor(() => p1.messages.filter(m => m.type === 'trajectory').length >= 2, 15000)
   await waitFor(() => p1.messages.slice(-1)[0]?.type === 'game_state', 15000)
   await new Promise(r => setTimeout(r, 500))
   console.log('Final stones', p1.messages.slice(-1)[0].stones)
   p1.ws.close()
-  p2.ws.close()
   process.exit(0)
 })().catch(e => {
   console.error(e)

e2e/e2e_test.cjs

@@ -12,7 +12,7 @@ function connect(name) {
       messages.push(msg)
       console.log(`[${name}]`, msg.type, msg.type === 'game_state' ? ` turn=${msg.turn_team}` : '')
       if (msg.type === 'joined') {
-        resolve({ ws, messages, team: msg.team })
+        resolve({ ws, messages })
       }
     })
     ws.on('open', () => console.log(`[${name}] open`))
@@ -21,31 +21,30 @@ function connect(name) {
   })
 }
 
-async function waitFor(condFn, timeout = 5000) {
+function waitFor(condFn, timeout = 5000) {
   const start = Date.now()
-  while (!condFn()) {
-    if (Date.now() - start > timeout) throw new Error('Timeout waiting')
-    await new Promise(r => setTimeout(r, 50))
+  return new Promise((resolve, reject) => {
+    const check = () => {
+      if (condFn()) return resolve(undefined)
+      if (Date.now() - start > timeout) return reject(new Error('Timeout waiting'))
+      setTimeout(check, 50)
     }
+    check()
+  })
 }
 
 ;(async () => {
   const p1 = await connect('p1')
-  await waitFor(() => p1.messages.some(m => m.type === 'waiting'))
-  const p2 = await connect('p2')
-  await waitFor(() => p2.messages.some(m => m.type === 'joined'))
   await waitFor(() => p1.messages.some(m => m.type === 'game_state'))
   const state = p1.messages.find(m => m.type === 'game_state')
   console.log('Game state', state)
 
   const turn = state.turn_team
-  const turnPlayer = turn === p1.team ? p1 : p2
-  turnPlayer.ws.send(JSON.stringify({ type: 'throw', broom_x: 0.5, broom_y: 39, weight: 7, curl: 1, friction: 1.0 }))
+  p1.ws.send(JSON.stringify({ type: 'throw', team: turn, broom_x: 0.5, broom_y: 39, weight: 7, curl: 1, friction: 1.0 }))
   await waitFor(() => p1.messages.some(m => m.type === 'trajectory'), 15000)
   await waitFor(() => p1.messages.slice(-1)[0]?.type === 'game_state', 15000)
   console.log('Final state after throw:', p1.messages.slice(-1)[0])
   p1.ws.close()
-  p2.ws.close()
   process.exit(0)
 })().catch(err => {
   console.error(err)

frontend/src/game-model.test.ts

@@ -0,0 +1,104 @@
+import { describe, expect, it } from 'vitest'
+import { GameModel } from './game-model'
+import type { ServerStoneTrajectory, StoneState } from './protocol'
+
+function stone(partial: Partial<StoneState> & Pick<StoneState, 'id' | 'team'>): StoneState {
+  return {
+    x: 0,
+    y: 30,
+    rotation: 0,
+    active: true,
+    ...partial,
+  }
+}
+
+describe('GameModel multi-path trajectory animation', () => {
+  it('returns two DrawableStones in parallel mid-trajectory', () => {
+    const model = new GameModel()
+    model.state.stones = [stone({ id: 1, team: 'red' }), stone({ id: 2, team: 'yellow' })]
+    model.state.turnTeam = 'red'
+
+    const paths: ServerStoneTrajectory[] = [
+      {
+        stone_id: 1,
+        path: [
+          [0, 10, 0],
+          [0, 11, 0.5],
+          [0, 12, 1.0],
+        ],
+      },
+      {
+        stone_id: 2,
+        path: [
+          [1, 10, 0],
+          [1, 11, 0.5],
+          [1, 12, 1.0],
+        ],
+      },
+    ]
+
+    model.startTrajectory(paths)
+    expect(model.state.animating).toBe(true)
+
+    const mid = performance.now() + 500
+    const drawn = model.tick(mid)
+
+    expect(drawn).toHaveLength(2)
+    expect(drawn.map((d) => d.team).sort()).toEqual(['red', 'yellow'])
+    // Mid-sample y ≈ 11 for both paths (y never reaches hog line → no trim shift)
+    for (const d of drawn) {
+      expect(d.y).toBeCloseTo(11, 0)
+    }
+  })
+
+  it('clears animating when elapsed reaches maxTotal on a short path', () => {
+    const model = new GameModel()
+    model.state.stones = [stone({ id: 1, team: 'red' })]
+    model.state.turnTeam = 'red'
+
+    model.startTrajectory([
+      {
+        stone_id: 1,
+        path: [
+          [0, 10, 0],
+          [0, 10.5, 0.2],
+          [0, 11, 0.4],
+        ],
+      },
+    ])
+    expect(model.state.animating).toBe(true)
+
+    const afterEnd = performance.now() + 500
+    const drawn = model.tick(afterEnd)
+
+    expect(drawn).toEqual([])
+    expect(model.state.animating).toBe(false)
+  })
+
+  it('trims thrown stone path to hog line when id is not in existing stones', () => {
+    const model = new GameModel()
+    // Only stone 1 is already on the sheet; stone 2 is the newly thrown rock.
+    model.state.stones = [stone({ id: 1, team: 'yellow', x: 0.5, y: 35 })]
+    model.state.turnTeam = 'red'
+
+    const thrownPath: [number, number, number][] = [
+      [0, 2, 0],
+      [0, 20, 1],
+      [0, 21.5, 2],
+      [0, 30, 3],
+    ]
+
+    model.startTrajectory([{ stone_id: 2, path: thrownPath }])
+    expect(model.state.animating).toBe(true)
+
+    // Immediately after start: hog-trimmed path begins at y=20 (sample before hog), t=0
+    const atStart = performance.now()
+    const drawn = model.tick(atStart)
+
+    expect(drawn).toHaveLength(1)
+    expect(drawn[0].team).toBe('red') // turnTeam fallback for unknown id
+    expect(drawn[0].y).toBeCloseTo(20, 0)
+    // Must not still be at the hack (y=2)
+    expect(drawn[0].y).toBeGreaterThan(15)
+  })
+})

frontend/src/game-model.ts

@@ -0,0 +1,182 @@
+import { HOG_LINE_Y, HOUSE_CENTER, type DrawableStone, type Phase, type ServerGameStateMessage, type ServerStoneTrajectory, type StoneState, type Team } from './protocol'
+import { trimPathToStartAtHogLine } from './game-helpers'
+
+export interface GameModelState {
+  end: number
+  scores: number[]
+  hammer: Team
+  turnTeam: Team
+  myTeam: Team | null
+  phase: Phase
+  stones: StoneState[]
+  animating: boolean
+}
+
+export class GameModel {
+  state: GameModelState = {
+    end: 1,
+    scores: [0, 0],
+    hammer: 'red',
+    turnTeam: 'red',
+    myTeam: null,
+    phase: 'waiting',
+    stones: [],
+    animating: false,
+  }
+
+  pendingStones: StoneState[] = []
+  broom: { x: number; y: number } = { x: 0, y: HOUSE_CENTER.y }
+  isDragging = false
+  isPanning = false
+
+  private activePaths = new Map<number, [number, number, number][]>()
+  private animationStartTime = 0
+
+  setMyTeam(team: Team): void {
+    this.state.myTeam = team
+  }
+
+  setWaiting(): void {
+    this.state.phase = 'waiting'
+  }
+
+  updateGameState(msg: ServerGameStateMessage): void {
+    const reset = msg.phase === 'waiting' || msg.end !== this.state.end
+    if (reset) {
+      this.state.stones = []
+      this.pendingStones = []
+    }
+
+    if (this.state.animating) {
+      this.pendingStones = msg.stones
+    } else {
+      this.state.stones = msg.stones
+    }
+
+    this.state = {
+      ...this.state,
+      end: msg.end,
+      scores: msg.scores,
+      hammer: msg.hammer,
+      turnTeam: msg.turn_team,
+      phase: msg.phase,
+    }
+  }
+
+  startTrajectory(paths: ServerStoneTrajectory[]): void {
+    const existingIds = new Set(this.state.stones.map((s) => s.id))
+
+    let thrownId: number | null = null
+    for (const { stone_id } of paths) {
+      if (!existingIds.has(stone_id)) {
+        thrownId = stone_id
+        break
+      }
+    }
+    if (thrownId === null && paths.length > 0) {
+      thrownId = paths[0].stone_id
+    }
+
+    let tRef = 0
+    if (thrownId !== null) {
+      const thrownPath = paths.find((p) => p.stone_id === thrownId)?.path ?? []
+      if (thrownPath.length >= 2) {
+        const idx = thrownPath.findIndex(([, y]) => y >= HOG_LINE_Y)
+        if (idx >= 0) {
+          const start = Math.max(0, idx - 1)
+          tRef = thrownPath[start][2]
+        }
+      }
+    }
+
+    const pathMap = new Map<number, [number, number, number][]>()
+    for (const { stone_id, path } of paths) {
+      if (stone_id === thrownId) {
+        pathMap.set(stone_id, trimPathToStartAtHogLine(path))
+      } else {
+        const shifted = path
+          .map(([x, y, t]) => [x, y, t - tRef] as [number, number, number])
+          .filter(([, , t]) => t >= 0)
+        pathMap.set(stone_id, shifted)
+      }
+    }
+
+    this.activePaths = pathMap
+    this.state.animating = Array.from(pathMap.values()).some((p) => p.length > 1)
+    this.animationStartTime = performance.now()
+    this.pendingStones = []
+  }
+
+  tick(now: number): DrawableStone[] {
+    if (!this.state.animating) {
+      return []
+    }
+
+    const elapsed = (now - this.animationStartTime) / 1000
+    const maxTotal = Math.max(
+      0,
+      ...Array.from(this.activePaths.values()).map((p) => (p.length > 0 ? p[p.length - 1][2] : 0)),
+    )
+
+    if (elapsed >= maxTotal) {
+      this.state.animating = false
+      if (this.pendingStones.length > 0) {
+        this.state.stones = this.pendingStones
+        this.pendingStones = []
+      }
+      return []
+    }
+
+    const result: DrawableStone[] = []
+    for (const [stoneId, path] of this.activePaths) {
+      const pos = this.interpolatePath(path, elapsed)
+      if (!pos) continue
+      const team = this.state.stones.find((s) => s.id === stoneId)?.team ?? this.state.turnTeam
+      result.push({ ...pos, team })
+    }
+    return result
+  }
+
+  private interpolatePath(
+    path: [number, number, number][],
+    elapsed: number,
+  ): { x: number; y: number; rotation: number } | null {
+    if (path.length === 0) return null
+    if (path.length === 1) {
+      const [x, y] = path[0]
+      return { x, y, rotation: 0 }
+    }
+
+    if (elapsed >= path[path.length - 1][2]) {
+      const last = path[path.length - 1]
+      const prev = path[path.length - 2]
+      const dx = last[0] - prev[0]
+      const dy = last[1] - prev[1]
+      return { x: last[0], y: last[1], rotation: Math.atan2(dy, dx) * 2 }
+    }
+
+    let i = 0
+    while (i + 1 < path.length && path[i + 1][2] < elapsed) i++
+    const p0 = path[i]
+    const p1 = path[i + 1] ?? p0
+    const t0 = path[Math.max(i - 1, 0)]
+    const t2 = path[Math.min(i + 2, path.length - 1)]
+    const dt = p1[2] - p0[2]
+    const t = dt > 0 ? (elapsed - p0[2]) / dt : 0
+    const x = p0[0] + (p1[0] - p0[0]) * t
+    const y = p0[1] + (p1[1] - p0[1]) * t
+    const dx = t2[0] - t0[0]
+    const dy = t2[1] - t0[1]
+    const rotation = Math.atan2(dy, dx) * 2
+    return { x, y, rotation }
+  }
+
+  get isMyTurn(): boolean {
+    return Boolean(
+      this.state.myTeam &&
+        this.state.turnTeam === this.state.myTeam &&
+        this.state.phase === 'playing' &&
+        !this.state.animating,
+    )
+  }
+}

frontend/src/game.ts

@@ -1,19 +1,8 @@
 import { connect, sendThrow, type NetCallbacks } from './net'
 import { createRenderer } from './renderer'
 import { createHud, createVelocitySelector, createCurlSelector, createFrictionSlider } from './hud'
-import { HOUSE_CENTER, HOUSE_RADIUS, type Phase, type StoneState, type Team } from './protocol'
-import { trimPathToStartAtHogLine } from './game-helpers'
-
-interface GameState {
-  end: number
-  scores: number[]
-  hammer: Team
-  turnTeam: Team
-  myTeam: Team | null
-  phase: Phase
-  stones: StoneState[]
-  animating: boolean
-}
+import { type Team } from './protocol'
+import { GameModel } from './game-model'
 
 export function startGame(): void {
   const app = document.querySelector<HTMLDivElement>('#app')!
@@ -24,6 +13,10 @@ export function startGame(): void {
   const hud = createHud()
   app.appendChild(hud.root)
 
+  if (import.meta.env.DEV) {
+    ;(window as unknown as { __renderer: typeof renderer }).__renderer = renderer
+  }
+
   const velocityContainer = hud.velocityControl
   const curlContainer = hud.curlSelector
   const frictionContainer = hud.frictionControl
@@ -42,141 +35,65 @@ export function startGame(): void {
   const shareLink = `${window.location.origin}/?room=${room}`
   hud.setShareLink(shareLink)
 
-  const picker = document.createElement('div')
-  picker.id = 'team-picker'
-  picker.innerHTML = `
-    <div class="team-picker-box">
-      <h2>Choose your team</h2>
-      <div class="team-picker-buttons">
-        <button class="team-btn team-red" data-team="red">Play as Red</button>
-        <button class="team-btn team-yellow" data-team="yellow">Play as Yellow</button>
-      </div>
-    </div>
-  `
-  app.appendChild(picker)
+  const model = new GameModel()
 
-  picker.querySelectorAll<HTMLButtonElement>('.team-btn').forEach((btn) => {
-    btn.addEventListener('click', () => {
-      const team = btn.dataset.team as Team
-      picker.remove()
-      connect(room, team, callbacks)
-    })
-  })
+  const initialTeam: Team = localStorage.getItem('curltastic-team') === 'yellow' ? 'yellow' : 'red'
+  model.setMyTeam(initialTeam)
+  hud.setTeam(initialTeam)
 
-  let gameState: GameState = {
-    end: 1,
-    scores: [0, 0],
-    hammer: 'red',
-    turnTeam: 'red',
-    myTeam: null,
-    phase: 'waiting',
-    stones: [],
-    animating: false,
-  }
-  let pendingStones: StoneState[] = []
-
-  let broom: { x: number; y: number } = { x: 0, y: HOUSE_CENTER.y }
-  let isDragging = false
-  let activePath: [number, number, number][] = []
-  let animationStartTime = 0
-  let animationTeam: Team = 'red'
+  // connect() is invoked after callbacks is defined below.
 
   const updateControls = () => {
-    const myTurn = Boolean(
-      gameState.myTeam && gameState.turnTeam === gameState.myTeam && gameState.phase === 'playing',
-    )
-    velocity.setEnabled(myTurn && !gameState.animating)
-    curls.setEnabled(myTurn && !gameState.animating)
-    friction.setEnabled(myTurn && !gameState.animating)
-    throwBtn.disabled = !myTurn || gameState.animating
-    if (gameState.phase === 'simulating' || gameState.animating) {
-      velocity.setEnabled(false)
-      curls.setEnabled(false)
-      friction.setEnabled(false)
-    }
-    hud.update(gameState)
+    const activeTeam = hud.teamSelect.value as Team
+    model.setMyTeam(activeTeam)
+    const myTurn = model.isMyTurn
+    velocity.setEnabled(myTurn)
+    curls.setEnabled(myTurn)
+    friction.setEnabled(myTurn)
+    throwBtn.disabled = !myTurn
+    hud.update(model.state)
   }
 
-  const render = () => {
-    let activeStonePos: { x: number; y: number; rotation: number; team: Team } | null = null
-    if (gameState.animating && activePath.length > 1) {
-      const elapsed = (performance.now() - animationStartTime) / 1000
-      const total = activePath[activePath.length - 1][2]
-      if (elapsed >= total) {
-        gameState.animating = false
-        if (pendingStones.length > 0) {
-          gameState.stones = pendingStones
-          pendingStones = []
-        }
+  hud.teamSelect.addEventListener('change', () => {
+    localStorage.setItem('curltastic-team', hud.teamSelect.value)
+    updateControls()
+  })
+
+  const render = () => {
+    const wasAnimating = model.state.animating
+    const activeStonePos = model.tick(performance.now())
+    if (wasAnimating && !model.state.animating) {
       updateControls()
-      } else {
-        let i = 0
-        while (i + 1 < activePath.length && activePath[i + 1][2] < elapsed) i++
-        const p0 = activePath[i]
-        const p1 = activePath[i + 1] ?? p0
-        const t0 = activePath[Math.max(i - 1, 0)]
-        const t2 = activePath[Math.min(i + 2, activePath.length - 1)]
-        const dt = p1[2] - p0[2]
-        const t = dt > 0 ? (elapsed - p0[2]) / dt : 0
-        const x = p0[0] + (p1[0] - p0[0]) * t
-        const y = p0[1] + (p1[1] - p0[1]) * t
-        const dx = t2[0] - t0[0]
-        const dy = t2[1] - t0[1]
-        const rotation = Math.atan2(dy, dx) * 2
-        activeStonePos = { x, y, rotation, team: animationTeam }
-      }
     }
 
     renderer.draw({
-      stones: gameState.stones,
+      stones: model.state.stones,
       broom:
-        gameState.phase === 'playing' && !gameState.animating && gameState.myTeam === gameState.turnTeam
-          ? broom
+        model.state.phase === 'playing' &&
+        !model.state.animating &&
+        model.state.myTeam === model.state.turnTeam
+          ? model.broom
           : null,
-      animating: gameState.animating,
+      animating: model.state.animating,
       activeStonePos,
     })
     requestAnimationFrame(render)
   }
 
   const callbacks: NetCallbacks = {
-    onJoined: (_roomId, team) => {
-      gameState.myTeam = team
+    onJoined: () => {
       updateControls()
     },
     onWaiting: () => {
-      gameState.phase = 'waiting'
+      model.setWaiting()
       updateControls()
     },
     onGameState: (msg) => {
-      const reset = msg.phase === 'waiting' || msg.end !== gameState.end
-      if (reset) {
-        gameState.stones = []
-        pendingStones = []
-      }
-
-      if (gameState.animating) {
-        pendingStones = msg.stones
-      } else {
-        gameState.stones = msg.stones
-      }
-
-      gameState = {
-        ...gameState,
-        end: msg.end,
-        scores: msg.scores,
-        hammer: msg.hammer,
-        turnTeam: msg.turn_team,
-        phase: msg.phase,
-      }
+      model.updateGameState(msg)
       updateControls()
     },
-    onTrajectory: (path) => {
-      activePath = trimPathToStartAtHogLine(path)
-      gameState.animating = activePath.length > 1
-      animationStartTime = performance.now()
-      animationTeam = gameState.turnTeam
-      pendingStones = []
+    onTrajectory: (paths) => {
+      model.startTrajectory(paths)
       updateControls()
     },
     onEndScored: (end, points, scoringTeam) => {
@@ -206,45 +123,45 @@ export function startGame(): void {
     return { x: e.clientX, y: e.clientY }
   }
 
-  const constrainBroom = (world: { x: number; y: number }) => {
-    const dx = world.x - HOUSE_CENTER.x
-    const dy = world.y - HOUSE_CENTER.y
-    const dist = Math.sqrt(dx * dx + dy * dy)
-    if (dist > HOUSE_RADIUS) {
-      const ratio = HOUSE_RADIUS / dist
-      return {
-        x: HOUSE_CENTER.x + dx * ratio,
-        y: HOUSE_CENTER.y + dy * ratio,
-      }
-    }
-    return world
-  }
+  let lastPanScreenY = 0
 
   const handleStart = (e: Event) => {
-    if (!isMyDragTurn()) return
-    isDragging = true
     const pos = getPos(e as TouchEvent)
-    broom = constrainBroom(renderer.screenToWorld(pos.x, pos.y))
+    const world = renderer.screenToWorld(pos.x, pos.y)
+
+    if (model.isMyTurn) {
+      model.isDragging = true
+      model.broom = world
+    } else {
+      model.isPanning = true
+      lastPanScreenY = pos.y
+    }
   }
 
   const handleMove = (e: Event) => {
-    if (!isDragging || !isMyDragTurn()) return
+    if (model.isDragging && model.isMyTurn) {
       e.preventDefault()
       const pos = getPos(e as TouchEvent)
-    broom = constrainBroom(renderer.screenToWorld(pos.x, pos.y))
+      model.broom = renderer.screenToWorld(pos.x, pos.y)
+      return
+    }
+
+    if (model.isPanning) {
+      e.preventDefault()
+      const pos = getPos(e as TouchEvent)
+      const prevWorld = renderer.screenToWorld(pos.x, lastPanScreenY)
+      const nowWorld = renderer.screenToWorld(pos.x, pos.y)
+      // Direct-manipulation pan: dragging the sheet down reveals the hog line above.
+      const deltaY = nowWorld.y - prevWorld.y
+      const sensitivity = 1.5
+      renderer.setViewYOffset(renderer.clampViewYOffset() + deltaY * sensitivity)
+      lastPanScreenY = pos.y
+    }
   }
 
   const handleEnd = () => {
-    isDragging = false
-  }
-
-  const isMyDragTurn = () => {
-    return (
-      gameState.myTeam !== null &&
-      gameState.turnTeam === gameState.myTeam &&
-      gameState.phase === 'playing' &&
-      !gameState.animating
-    )
+    model.isDragging = false
+    model.isPanning = false
   }
 
   canvas.addEventListener('touchstart', handleStart, { passive: false })
@@ -256,10 +173,18 @@ export function startGame(): void {
   canvas.addEventListener('mouseleave', handleEnd)
 
   throwBtn.addEventListener('click', () => {
-    if (gameState.myTeam !== gameState.turnTeam || gameState.animating || gameState.phase !== 'playing') return
-    sendThrow(broom.x, broom.y, velocity.getWeight(), curls.getSelected(), friction.getFriction())
+    if (!model.isMyTurn) return
+    sendThrow(
+      hud.teamSelect.value as Team,
+      model.broom.x,
+      model.broom.y,
+      velocity.getWeight(),
+      curls.getSelected(),
+      friction.getFriction(),
+    )
   })
 
+  connect(room, callbacks)
   updateControls()
   render()
 }

frontend/src/hud.ts

@@ -3,17 +3,18 @@ import { velocityToWeight, weightToVelocity } from './game-helpers'
 
 export interface Hud {
   root: HTMLDivElement
+  teamSelect: HTMLSelectElement
   velocityControl: HTMLDivElement
   curlSelector: HTMLDivElement
   frictionControl: HTMLDivElement
   throwButton: HTMLButtonElement
+  setTeam: (team: Team) => void
   update: (state: {
     phase: Phase
     end: number
     scores: number[]
     hammer: Team
     turnTeam: Team
-    myTeam: Team | null
     animating: boolean
   }) => void
   showToast: (message: string) => void
@@ -48,12 +49,20 @@ export function createHud(): Hud {
   const root = document.createElement('div')
   root.id = 'hud'
   root.innerHTML = `
+    <div id="hud-top-group">
+      <div class="hud-row" id="share-row">
+        <div id="share"><button>Copy share link</button></div>
+      </div>
       <div class="hud-row">
         <div id="score">Red 0 - Yellow 0</div>
         <div id="end-info">End 1 · Waiting</div>
-      <div id="team">You: -</div>
+        <select id="team-select" aria-label="Team">
+          <option value="red">Red</option>
+          <option value="yellow">Yellow</option>
+        </select>
         <div id="hammer">Hammer: -</div>
       </div>
+    </div>
     <div class="hud-row" style="align-items:flex-end;">
       <div id="velocity-control"></div>
       <div id="curl-selector"></div>
@@ -66,34 +75,32 @@ export function createHud(): Hud {
         <button id="throw-btn" disabled>THROW</button>
       </div>
     </div>
-    <div id="waiting">Waiting for other player</div>
-    <div id="share"><button>Copy share link</button></div>
+    <div id="waiting">Waiting</div>
   `
 
   const scoreEl = root.querySelector<HTMLDivElement>('#score')!
   const endInfoEl = root.querySelector<HTMLDivElement>('#end-info')!
-  const teamEl = root.querySelector<HTMLDivElement>('#team')!
+  const teamSelect = root.querySelector<HTMLSelectElement>('#team-select')!
   const hammerEl = root.querySelector<HTMLDivElement>('#hammer')!
   const waitingEl = root.querySelector<HTMLDivElement>('#waiting')!
 
   return {
     root,
+    teamSelect,
     velocityControl: root.querySelector<HTMLDivElement>('#velocity-control')!,
     curlSelector: root.querySelector<HTMLDivElement>('#curl-selector')!,
     frictionControl: root.querySelector<HTMLDivElement>('#friction-control')!,
     throwButton: root.querySelector<HTMLButtonElement>('#throw-btn')!,
+    setTeam: (team) => {
+      teamSelect.value = team
+    },
     update: (state) => {
       scoreEl.textContent = `Red ${state.scores[0] ?? 0} - Yellow ${state.scores[1] ?? 0}`
       const teamNames: Record<Team, string> = { red: 'Red', yellow: 'Yellow' }
       const phaseText = state.phase === 'playing' ? `${teamNames[state.turnTeam]}'s turn` : state.phase.replace(/_/g, ' ')
       endInfoEl.textContent = `End ${state.end} · ${phaseText}`
-      teamEl.textContent = state.myTeam ? `You: ${teamNames[state.myTeam]}` : 'You: -'
       hammerEl.textContent = `Hammer: ${teamNames[state.hammer]}`
-      const waiting =
-        state.phase === 'waiting' ||
-        (state.phase === 'playing' && state.myTeam !== null && state.turnTeam !== state.myTeam) ||
-        state.animating
-      waitingEl.classList.toggle('visible', state.phase !== 'game_complete' && waiting)
+      waitingEl.classList.toggle('visible', state.phase !== 'game_complete' && state.animating)
     },
     showToast: (message: string) => {
       const toast = document.createElement('div')
@@ -179,14 +186,15 @@ export function createCurlSelector(
 ): { getSelected: () => number; setEnabled: (enabled: boolean) => void } {
   const state = { selected: 1, enabled: true }
   const options = [
-    { value: -1, label: '↶ Left' },
-    { value: 1, label: 'Right ↷' },
+    { value: -1, label: '↷', ariaLabel: 'Left curl' },
+    { value: 1, label: '↶', ariaLabel: 'Right curl' },
   ]
   container.innerHTML = ''
   for (const opt of options) {
     const btn = document.createElement('button')
     btn.className = 'curl-btn'
     btn.textContent = opt.label
+    btn.ariaLabel = opt.ariaLabel
     btn.dataset.curl = String(opt.value)
     btn.addEventListener('click', () => {
       if (!state.enabled) return

frontend/src/net.ts

@@ -1,5 +1,6 @@
 import type {
   ServerGameStateMessage,
+  ServerStoneTrajectory,
   ServerMessageTyped as ServerMessage,
   Team,
 } from './protocol'
@@ -13,10 +14,10 @@ function resolveWsUrl(): string {
 }
 
 export interface NetCallbacks {
-  onJoined: (room: string, team: Team) => void
+  onJoined: (room: string) => void
   onWaiting: (message: string) => void
   onGameState: (msg: ServerGameStateMessage) => void
-  onTrajectory: (path: [number, number, number][]) => void
+  onTrajectory: (paths: ServerStoneTrajectory[]) => void
   onEndScored: (end: number, points: number, scoringTeam: Team | null) => void
   onGameOver: (scores: number[], winner: Team | null) => void
   onError: (message: string) => void
@@ -25,10 +26,9 @@ export interface NetCallbacks {
 
 let socket: WebSocket | null = null
 
-export function connect(room: string, team: Team | null, callbacks: NetCallbacks): void {
+export function connect(room: string, callbacks: NetCallbacks): void {
   if (socket) return
-  const teamParam = team ? `&team=${encodeURIComponent(team)}` : ''
-  const url = `${resolveWsUrl()}?room=${encodeURIComponent(room)}${teamParam}`
+  const url = `${resolveWsUrl()}?room=${encodeURIComponent(room)}`
   const ws = new WebSocket(url)
 
   ws.onopen = () => {
@@ -42,7 +42,7 @@ export function connect(room: string, team: Team | null, callbacks: NetCallbacks
 
       switch (msg.type) {
         case 'joined':
-          callbacks.onJoined(msg.room, msg.team)
+          callbacks.onJoined(msg.room)
           break
         case 'waiting':
           callbacks.onWaiting(msg.message)
@@ -51,7 +51,7 @@ export function connect(room: string, team: Team | null, callbacks: NetCallbacks
           callbacks.onGameState(msg)
           break
         case 'trajectory':
-          callbacks.onTrajectory(msg.path)
+          callbacks.onTrajectory(msg.paths)
           break
         case 'end_scored':
           callbacks.onEndScored(msg.end, msg.points, msg.scoring_team ?? null)
@@ -76,7 +76,24 @@ export function connect(room: string, team: Team | null, callbacks: NetCallbacks
   ws.onerror = () => {}
 }
 
-export function sendThrow(broomX: number, broomY: number, weight: number, curl: number, friction: number): void {
+export function sendThrow(
+  team: Team,
+  broomX: number,
+  broomY: number,
+  weight: number,
+  curl: number,
+  friction: number,
+): void {
   if (!socket || socket.readyState !== WebSocket.OPEN) return
-  socket.send(JSON.stringify({ type: 'throw', broom_x: broomX, broom_y: broomY, weight, curl, friction }))
+  socket.send(
+    JSON.stringify({
+      type: 'throw',
+      team,
+      broom_x: broomX,
+      broom_y: broomY,
+      weight,
+      curl,
+      friction,
+    }),
+  )
 }

frontend/src/protocol.ts

@@ -4,12 +4,13 @@ export const STONES_PER_TEAM = 8
 export const ENDS = 10
 export const SHEET_WIDTH = 5.0
 export const SHEET_LENGTH = 45.0
+export const FEET_TO_METERS = 0.3048
 export const HOUSE_CENTER = { x: 0, y: 38.5 }
-export const HOUSE_RADIUS = 1.83
-export const BUTTON_RADIUS = 0.1524
-export const FOUR_FT_RADIUS = 0.6096
-export const EIGHT_FT_RADIUS = 1.2192
-export const TWELVE_FT_RADIUS = 1.8288
+export const HOUSE_RADIUS = 6 * FEET_TO_METERS
+export const BUTTON_RADIUS = 0.5 * FEET_TO_METERS
+export const FOUR_FT_RADIUS = 2 * FEET_TO_METERS
+export const EIGHT_FT_RADIUS = 4 * FEET_TO_METERS
+export const TWELVE_FT_RADIUS = 6 * FEET_TO_METERS
 export const HOG_LINE_Y = 21.0
 export const BACK_LINE_Y = 42.0
 export const HACK_Y = 2.0
@@ -26,8 +27,16 @@ export interface StoneState {
   active: boolean
 }
 
+export interface DrawableStone {
+  x: number
+  y: number
+  rotation: number
+  team: Team
+}
+
 export interface ClientThrowMessage {
   type: 'throw'
+  team: Team
   broom_x: number
   broom_y: number
   weight: number
@@ -38,7 +47,6 @@ export interface ClientThrowMessage {
 export interface ServerJoinedMessage {
   type: 'joined'
   room: string
-  team: Team
 }
 
 export interface ServerWaitingMessage {
@@ -56,9 +64,14 @@ export interface ServerGameStateMessage {
   phase: Phase
 }
 
+export interface ServerStoneTrajectory {
+  stone_id: number
+  path: [number, number, number][]
+}
+
 export interface ServerTrajectoryMessage {
   type: 'trajectory'
-  path: [number, number, number][]
+  paths: ServerStoneTrajectory[]
 }
 
 export interface ServerEndScoredMessage {

frontend/src/renderer.ts

@@ -9,8 +9,8 @@ import {
   STONE_RADIUS,
   TWELVE_FT_RADIUS,
   HOUSE_CENTER,
+  type DrawableStone,
   type StoneState,
-  type Team,
 } from './protocol'
 
 export interface Renderer {
@@ -19,19 +19,31 @@ export interface Renderer {
   setSize: () => void
   worldToScreen: (x: number, y: number) => { x: number; y: number }
   screenToWorld: (sx: number, sy: number) => { x: number; y: number }
+  setViewYOffset: (y: number) => void
+  clampViewYOffset: () => number
   draw: (state: {
     stones: StoneState[]
     broom: { x: number; y: number } | null
     animating: boolean
-    activeStonePos: { x: number; y: number; rotation: number; team: Team } | null
+    activeStonePos: DrawableStone[]
   }) => void
 }
 
 export function createRenderer(canvas: HTMLCanvasElement): Renderer {
   const ctx = canvas.getContext('2d')!
-  // Show the area from the hog line (top) to the back line (bottom).
-  const viewportHeight = BACK_LINE_Y - HOG_LINE_Y
-  const viewportCenter = { x: 0, y: (HOG_LINE_Y + BACK_LINE_Y) / 2 }
+  // Fit full sheet width (5 m) with a little side padding so both sidelines show.
+  // Scale is primarily width-based, but also capped so house + backline fit above the HUD.
+  const SIDE_PADDING_M = 0.25
+  const viewportWidth = SHEET_WIDTH + SIDE_PADDING_M * 2
+  // Min world height: top of 12ft ring through backline + small pad.
+  const MIN_VIEW_HEIGHT_M =
+    BACK_LINE_Y - (HOUSE_CENTER.y - TWELVE_FT_RADIUS) + SIDE_PADDING_M
+  // Throw button (80) + hud padding (12×2) + small gap above controls.
+  const BOTTOM_UI_PX = 120
+  const viewportCenter = { x: 0, y: HOUSE_CENTER.y }
+  // Prefer backline at the bottom of the usable ice area (just above HUD).
+  // First setSize()/setViewYOffset clamps this to the valid minOffset.
+  let viewportYOffset = -(BACK_LINE_Y - HOUSE_CENTER.y)
 
   const setSize = () => {
     const dpr = window.devicePixelRatio || 1
@@ -42,33 +54,75 @@ export function createRenderer(canvas: HTMLCanvasElement): Renderer {
     canvas.style.width = `${width}px`
     canvas.style.height = `${height}px`
     ctx.setTransform(dpr, 0, 0, dpr, 0, 0)
+    // Re-clamp so default framing keeps the backline just above the HUD.
+    setViewYOffset(viewportYOffset)
+  }
+
+  /** Screen height available for ice (above bottom controls). */
+  const usableHeightPx = (): number => {
+    return Math.max(1, window.innerHeight - BOTTOM_UI_PX)
   }
 
   const scale = (): number => {
-    const height = window.innerHeight
-    return height / viewportHeight
+    const byWidth = window.innerWidth / viewportWidth
+    const byHeight = usableHeightPx() / MIN_VIEW_HEIGHT_M
+    // Width fit for sidelines; height cap so house/backline stay on-screen on wide displays.
+    return Math.min(byWidth, byHeight)
   }
 
+  const viewportHeight = (): number => {
+    return usableHeightPx() / scale()
+  }
+
+  /** Vertical center of the usable ice area (not the full window). */
+  const viewCenterY = (): number => {
+    return usableHeightPx() / 2
+  }
+
+  const effectiveViewportCenter = () => ({
+    x: viewportCenter.x,
+    y: viewportCenter.y - viewportYOffset,
+  })
+
   const worldToScreen = (x: number, y: number) => {
     const s = scale()
     const cx = window.innerWidth / 2
-    const cy = window.innerHeight / 2
+    const cy = viewCenterY()
+    const center = effectiveViewportCenter()
     return {
-      x: cx + (x - viewportCenter.x) * s,
-      y: cy + (y - viewportCenter.y) * s,
+      x: cx + (x - center.x) * s,
+      y: cy + (y - center.y) * s,
     }
   }
 
   const screenToWorld = (sx: number, sy: number) => {
     const s = scale()
     const cx = window.innerWidth / 2
-    const cy = window.innerHeight / 2
+    const cy = viewCenterY()
+    const center = effectiveViewportCenter()
     return {
-      x: (sx - cx) / s + viewportCenter.x,
-      y: viewportCenter.y + (sy - cy) / s,
+      x: (sx - cx) / s + center.x,
+      y: center.y + (sy - cy) / s,
     }
   }
 
+  const clampViewYOffset = (): number => {
+    // Positive offset pans the view upward (toward the hog line).
+    // When the usable viewport is tall enough, minOffset pins BACK_LINE_Y to the
+    // bottom of the usable area (just above the HUD), not under the controls.
+    const halfHeight = viewportHeight() / 2
+    const maxOffset = HOUSE_CENTER.y - halfHeight - HOG_LINE_Y
+    const minOffset = -(BACK_LINE_Y - (HOUSE_CENTER.y + halfHeight))
+    return Math.max(minOffset, Math.min(maxOffset, viewportYOffset))
+  }
+
+  const setViewYOffset = (y: number) => {
+    const halfHeight = viewportHeight() / 2
+    const maxOffset = HOUSE_CENTER.y - halfHeight - HOG_LINE_Y
+    const minOffset = -(BACK_LINE_Y - (HOUSE_CENTER.y + halfHeight))
+    viewportYOffset = Math.max(minOffset, Math.min(maxOffset, y))
+  }
+
   const drawLine = (
     x1: number,
     y1: number,
@@ -102,7 +156,7 @@ export function createRenderer(canvas: HTMLCanvasElement): Renderer {
     }
   }
 
-  const drawStone = (stone: StoneState | { x: number; y: number; rotation: number; team: Team }) => {
+  const drawStone = (stone: DrawableStone) => {
     const c = worldToScreen(stone.x, stone.y)
     const r = STONE_RADIUS * scale()
     const color = stone.team === 'red' ? '#d93025' : '#f9ab00'
@@ -129,7 +183,7 @@ export function createRenderer(canvas: HTMLCanvasElement): Renderer {
     stones: StoneState[]
     broom: { x: number; y: number } | null
     animating: boolean
-    activeStonePos: { x: number; y: number; rotation: number; team: Team } | null
+    activeStonePos: DrawableStone[]
   }) => {
     ctx.clearRect(0, 0, window.innerWidth, window.innerHeight)
 
@@ -149,12 +203,14 @@ export function createRenderer(canvas: HTMLCanvasElement): Renderer {
     drawCircle(HOUSE_CENTER.x, HOUSE_CENTER.y, FOUR_FT_RADIUS, 'rgba(255,255,255,0.12)', 'rgba(255,255,255,0.35)')
     drawCircle(HOUSE_CENTER.x, HOUSE_CENTER.y, BUTTON_RADIUS, '#e8e8e8', '#fff')
 
+    if (state.animating) {
+      for (const stone of state.activeStonePos) {
+        drawStone(stone)
+      }
+    } else {
       for (const stone of state.stones) {
         drawStone(stone)
       }
-
-    if (state.activeStonePos) {
-      drawStone(state.activeStonePos)
     }
 
     if (state.broom) {
@@ -170,5 +226,5 @@ export function createRenderer(canvas: HTMLCanvasElement): Renderer {
   setSize()
   window.addEventListener('resize', setSize)
 
-  return { canvas, ctx, setSize, worldToScreen, screenToWorld, draw }
+  return { canvas, ctx, setSize, worldToScreen, screenToWorld, setViewYOffset, clampViewYOffset, draw }
 }

frontend/src/style.css

@@ -84,30 +84,57 @@ html, body {
   z-index: 10;
 }
 
+#hud-top-group {
+  display: flex;
+  flex-direction: column;
+  gap: 4px;
+}
+
 #share {
-  position: absolute;
-  bottom: 12px;
-  left: 50%;
-  transform: translateX(-50%);
-  text-align: center;
+  display: flex;
+  justify-content: center;
+  width: 100%;
+}
+
+#share-row {
+  justify-content: center;
+  margin-bottom: 4px;
+}
+
+#share-row #share {
+  position: static;
+  transform: none;
 }
 
 #share button {
   background: rgba(255, 255, 255, 0.15);
   border: 1px solid rgba(255, 255, 255, 0.3);
   color: white;
-  padding: 8px 14px;
+  padding: 6px 12px;
   border-radius: 12px;
-  font-size: 13px;
+  font-size: 12px;
   pointer-events: auto;
 }
 
 #team {
+  display: none;
+}
+
+#team-select {
   font-size: 13px;
   font-weight: 600;
   padding: 4px 8px;
   border-radius: 10px;
-  background: rgba(255, 255, 255, 0.1);
+  background: rgba(255, 255, 255, 0.15);
+  color: white;
+  border: 1px solid rgba(255, 255, 255, 0.3);
+  pointer-events: auto;
+  min-width: 80px;
+}
+
+#team-select option {
+  background: #0b1f3a;
+  color: white;
 }
 
 #velocity-control {
@@ -205,67 +232,6 @@ html, body {
   text-align: center;
 }
 
-#team-picker {
-  position: absolute;
-  top: 0;
-  left: 0;
-  right: 0;
-  bottom: 0;
-  background: rgba(0, 0, 0, 0.75);
-  display: flex;
-  align-items: center;
-  justify-content: center;
-  z-index: 20;
-  pointer-events: auto;
-}
-
-.team-picker-box {
-  background: #0b1f3a;
-  border: 1px solid rgba(255, 255, 255, 0.2);
-  border-radius: 16px;
-  padding: 24px;
-  text-align: center;
-  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.4);
-}
-
-.team-picker-box h2 {
-  margin: 0 0 16px 0;
-  font-size: 18px;
-}
-
-.team-picker-buttons {
-  display: flex;
-  gap: 16px;
-  justify-content: center;
-  flex-wrap: wrap;
-}
-
-.team-btn {
-  width: 120px;
-  height: 120px;
-  border-radius: 16px;
-  border: 2px solid rgba(255, 255, 255, 0.4);
-  color: white;
-  font-weight: 700;
-  font-size: 16px;
-  cursor: pointer;
-  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.3);
-}
-
-.team-btn.team-red {
-  background: #cc3333;
-}
-.team-btn.team-red:hover {
-  background: #e04444;
-}
-
-.team-btn.team-yellow {
-  background: #ccaa00;
-}
-.team-btn.team-yellow:hover {
-  background: #e0be00;
-}
-
 #throw-btn {
   width: 80px;
   height: 80px;
@@ -283,3 +249,53 @@ html, body {
   background: #557766;
   color: rgba(255, 255, 255, 0.5);
 }
+
+@media (max-width: 480px) {
+  #hud {
+    padding: 8px;
+  }
+
+  .hud-row {
+    gap: 6px;
+  }
+
+  #velocity-control {
+    min-width: 0;
+    flex: 1 1 auto;
+    padding: 2px;
+  }
+
+  .velocity-readout {
+    min-width: 0;
+    font-size: 10px;
+  }
+
+  .curl-btn {
+    min-width: 44px;
+    width: 44px;
+    height: 36px;
+    font-size: 18px;
+    border-color: rgba(255, 255, 255, 0.6);
+    background: rgba(0, 0, 0, 0.5);
+  }
+
+  #friction-control {
+    min-width: 0;
+    flex: 0 1 auto;
+    padding: 2px;
+  }
+
+  #friction-slider {
+    width: 60px;
+  }
+
+  #friction-value {
+    font-size: 10px;
+  }
+
+  #throw-btn {
+    width: 56px;
+    height: 56px;
+    font-size: 12px;
+  }
+}