Add WebRTC support and remove deviceId from apis

server/internal/control/race.go

@@ -47,6 +47,7 @@ type Car struct {
 	ID         string
 	DriverID   string // session id
 	DriverName string
+	DeviceID   *int   // internal mapping to physical ESP32 device ID
 	X, Y       float64
 	Heading    float64 // radians
 	Speed      float64 // m/s
@@ -169,7 +170,7 @@ func (e *Engine) SetPhase(p RacePhase) { e.phase.Store(int32(p)) }
 
 // AddCar registers a car and returns it. Returns an error if the driver
 // already has a car or the max car count is reached.
-func (e *Engine) AddCar(driverID, driverName string, slot int) (*Car, error) {
+func (e *Engine) AddCar(driverID, driverName string, slot int, deviceID *int) (*Car, error) {
 	e.mu.Lock()
 	defer e.mu.Unlock()
 
@@ -185,6 +186,7 @@ func (e *Engine) AddCar(driverID, driverName string, slot int) (*Car, error) {
 		ID:         id,
 		DriverID:   driverID,
 		DriverName: driverName,
+		DeviceID:   deviceID,
 		// Spread cars along start grid (x = 0, y = slot * 0.4 m).
 		Y: float64(slot) * 0.4,
 	}

server/internal/lobby/types.go

@@ -65,7 +65,7 @@ type DriverMeta struct {
 	LastSeenMs  int64        `json:"last_seen_ms"`
 	Country     string       `json:"country,omitempty"` // optional, for UI
 	AvatarHue   int          `json:"avatar_hue,omitempty"` // 0..360, deterministic per id
-	DeviceID    *int         `json:"device_id,omitempty"`
+	DeviceID    *int         `json:"-"`
 }
 
 // Snapshot is the immutable view broadcast to clients.

server/internal/transport/codec.go

@@ -239,6 +239,19 @@ type VersionResponse struct {
 	Version string `json:"version" example:"0.1.0-poc"`
 }
 
+// WebRTCConnectRequest is the body of the WebRTC connection API.
+type WebRTCConnectRequest struct {
+	SDP      string `json:"sdp"`
+	Type     string `json:"type" example:"offer"`
+	DriverID string `json:"driver_id" example:"driver-alice"`
+}
+
+// WebRTCConnectResponse is the response to WebRTCConnectRequest.
+type WebRTCConnectResponse struct {
+	SDP  string `json:"sdp"`
+	Type string `json:"type" example:"answer"`
+}
+
 // LobbyDriver is the wire form of lobby.DriverMeta.
 type LobbyDriver struct {
 	ID          string `json:"id"`
@@ -249,7 +262,6 @@ type LobbyDriver struct {
 	LastSeenMs  int64  `json:"last_seen_ms"`
 	Country     string `json:"country,omitempty"`
 	AvatarHue   int    `json:"avatar_hue,omitempty"`
-	DeviceID    *int   `json:"device_id,omitempty"`
 }
 
 // LobbySnapshot is the full lobby state, broadcast on change.