feat(client): implement server-initiated mode with WebSocket support

third_party/sendspin-go/pkg/sendspin/player.go

@@ -14,6 +14,7 @@ import (
 	"github.com/Sendspin/sendspin-go/pkg/audio/output"
 	"github.com/Sendspin/sendspin-go/pkg/protocol"
 	"github.com/Sendspin/sendspin-go/pkg/sync"
+	"github.com/gorilla/websocket"
 )
 
 // ReconnectConfig controls automatic reconnect behavior after the protocol
@@ -216,6 +217,55 @@ func (p *Player) Connect() error {
 	return nil
 }
 
+// Accept drives the player over a server-initiated WebSocket connection
+// (the server discovered this player via mDNS and dialed it). It builds a
+// receiver over the accepted conn, starts audio consumption, and BLOCKS
+// until the connection drops or the player is closed — so callers running a
+// listener can serialize one session at a time and re-accept on return.
+//
+// Unlike Connect, Accept does not start the dial-based reconnect loop: in
+// server-initiated mode the server redials, so reconnection is the listener's
+// responsibility, not the player's. The caller transfers ownership of conn.
+func (p *Player) Accept(conn *websocket.Conn) error {
+	recv, err := p.buildReceiver("server-initiated")
+	if err != nil {
+		return err
+	}
+	if err := recv.AcceptConn(conn); err != nil {
+		return err
+	}
+
+	p.receiver = recv
+	p.state.Connected = true
+	p.notifyStateChange()
+
+	go p.consumeAudio(recv)
+
+	// Block for the lifetime of this connection so the caller's accept loop
+	// serializes sessions (one server connection at a time).
+	select {
+	case <-recv.Done():
+	case <-p.ctx.Done():
+	}
+
+	recv.Close()
+	p.state.Connected = false
+	p.state.State = "idle"
+	p.notifyStateChange()
+
+	return nil
+}
+
+// CloseConnection drops the currently active receiver, if any, without
+// tearing down the Player or its audio output. In server-initiated mode a
+// listener calls this to evict a stale/superseded session before accepting
+// a newer connection; the blocked Accept for the old session then returns.
+func (p *Player) CloseConnection() {
+	if p.receiver != nil {
+		p.receiver.Close()
+	}
+}
+
 func (p *Player) buildReceiver(addr string) (*Receiver, error) {
 	p.ensureCapsResolved()
 	return NewReceiver(ReceiverConfig{