feat: add VideoTrack capability to provider and carrier interfaces

internal/carrier/bytestream.go

@@ -19,13 +19,20 @@ type ByteStream interface {
 	CanSend() bool
 }
 
+// VideoTrack is a carrier capability for publishing a local video track.
+type VideoTrack interface {
+	AddTrack(track *webrtc.TrackLocalStaticRTP) (*webrtc.RTPSender, error)
+}
+
 type legacySession struct {
 	provider provider.Provider
 }
 
 // Capabilities reports the transport primitives supported by the legacy carrier.
 func (s *legacySession) Capabilities() Capabilities {
-	return Capabilities{ByteStream: true}
+	caps := Capabilities{ByteStream: true}
+	_, caps.VideoTrack = s.provider.(provider.VideoTrackCapable)
+	return caps
 }
 
 // OpenByteStream adapts the legacy provider to a generic byte stream capability.
@@ -33,6 +40,15 @@ func (s *legacySession) OpenByteStream() (ByteStream, error) {
 	return &legacyByteStream{provider: s.provider}, nil
 }
 
+// OpenVideoTrack adapts a legacy provider to the generic video track capability.
+func (s *legacySession) OpenVideoTrack() (VideoTrack, error) {
+	publisher, ok := s.provider.(provider.VideoTrackCapable)
+	if !ok {
+		return nil, ErrVideoTrackUnsupported
+	}
+	return &legacyVideoTrack{provider: publisher}, nil
+}
+
 type legacyByteStream struct {
 	provider provider.Provider
 }
@@ -55,3 +71,11 @@ func (p *legacyByteStream) WatchConnection(ctx context.Context) {
 	p.provider.WatchConnection(ctx)
 }
 func (p *legacyByteStream) CanSend() bool { return p.provider.CanSend() }
+
+type legacyVideoTrack struct {
+	provider provider.VideoTrackCapable
+}
+
+func (v *legacyVideoTrack) AddTrack(track *webrtc.TrackLocalStaticRTP) (*webrtc.RTPSender, error) {
+	return v.provider.AddVideoTrack(track)
+}

internal/carrier/carrier.go

@@ -13,11 +13,14 @@ var (
 	ErrCarrierNotFound = errors.New("carrier not found")
 	// ErrByteStreamUnsupported is returned when a carrier cannot provide a byte stream.
 	ErrByteStreamUnsupported = errors.New("carrier does not support byte stream")
+	// ErrVideoTrackUnsupported is returned when a carrier cannot publish video tracks.
+	ErrVideoTrackUnsupported = errors.New("carrier does not support video tracks")
 )
 
 // Capabilities describes the transport primitives a carrier can expose.
 type Capabilities struct {
 	ByteStream bool
+	VideoTrack bool
 }
 
 // Session is the carrier-level runtime handle.
@@ -30,6 +33,11 @@ type ByteStreamCapable interface {
 	OpenByteStream() (ByteStream, error)
 }
 
+// VideoTrackCapable is implemented by carriers that can publish video tracks.
+type VideoTrackCapable interface {
+	OpenVideoTrack() (VideoTrack, error)
+}
+
 // Config holds carrier configuration.
 type Config struct {
 	RoomURL   string

internal/provider/provider.go

@@ -35,8 +35,10 @@ type Provider interface {
 	CanSend() bool
 	GetSendQueue() chan []byte
 	GetBufferedAmount() uint64
+}
 
-	// AddVideoTrack adds a video track to the connection.
+// VideoTrackCapable is implemented by providers that can publish video tracks.
+type VideoTrackCapable interface {
 	AddVideoTrack(track *webrtc.TrackLocalStaticRTP) (*webrtc.RTPSender, error)
 }