Support chat data messages.

Author: dennwc

data.go

@@ -1,6 +1,9 @@
 package lksdk
 
 import (
+	"time"
+
+	"github.com/livekit/protocol/utils/guid"
 	"google.golang.org/protobuf/proto"
 
 	"github.com/livekit/protocol/livekit"
@@ -15,7 +18,8 @@ type DataPacket interface {
 // Compile-time assertion for all supported data packet types.
 var (
 	_ DataPacket = (*UserDataPacket)(nil)
-	_ DataPacket = (*livekit.SipDTMF)(nil) // implemented in the protocol package
+	_ DataPacket = (*livekit.SipDTMF)(nil)     // implemented in the protocol package
+	_ DataPacket = (*livekit.ChatMessage)(nil) // implemented in the protocol package
 )
 
 // UserData is a custom user data that can be sent via WebRTC.
@@ -43,6 +47,18 @@ func (p *UserDataPacket) ToProto() *livekit.DataPacket {
 	}}
 }
 
+// ChatMessage creates a chat message that can be sent via WebRTC.
+func ChatMessage(ts time.Time, text string) *livekit.ChatMessage {
+	if ts.IsZero() {
+		ts = time.Now()
+	}
+	return &livekit.ChatMessage{
+		Id:        guid.New("MSG_"),
+		Timestamp: ts.UnixMilli(),
+		Message:   text,
+	}
+}
+
 // receiving
 
 type DataReceiveParams struct {

engine.go

@@ -30,6 +30,7 @@ import (
 	"github.com/livekit/protocol/livekit"
 	protoLogger "github.com/livekit/protocol/logger"
 	protosignalling "github.com/livekit/protocol/signalling"
+
 	"github.com/livekit/server-sdk-go/v2/signalling"
 )
 
@@ -598,6 +599,8 @@ func (e *RTCEngine) handleDataPacket(msg webrtc.DataChannelMessage) {
 		})
 	case *livekit.DataPacket_SipDtmf:
 		e.engineHandler.OnDataPacket(identity, msg.SipDtmf)
+	case *livekit.DataPacket_ChatMessage:
+		e.engineHandler.OnDataPacket(identity, msg.ChatMessage)
 	case *livekit.DataPacket_Transcription:
 		e.engineHandler.OnTranscription(msg.Transcription)
 	case *livekit.DataPacket_RpcRequest:

go.mod

@@ -10,7 +10,7 @@ require (
 	github.com/livekit/mageutil v0.0.0-20250511045019-0f1ff63f7731
 	github.com/livekit/media-sdk v0.0.0-20250518151703-b07af88637c5
 	github.com/livekit/mediatransportutil v0.0.0-20250519131108-fb90f5acfded
-	github.com/livekit/protocol v1.39.4-0.20250725083335-7313a8195a4b
+	github.com/livekit/protocol v1.39.4-0.20250729112356-c072a903cb08 // FIXME: replace when PR is merged
 	github.com/magefile/mage v1.15.0
 	github.com/pion/dtls/v3 v3.0.6
 	github.com/pion/interceptor v0.1.40

go.sum

@@ -99,8 +99,8 @@ github.com/livekit/media-sdk v0.0.0-20250518151703-b07af88637c5 h1:aFCwt/rticj5L
 github.com/livekit/media-sdk v0.0.0-20250518151703-b07af88637c5/go.mod h1:7ssWiG+U4xnbvLih9WiZbhQP6zIKMjgXdUtIE1bm/E8=
 github.com/livekit/mediatransportutil v0.0.0-20250519131108-fb90f5acfded h1:ylZPdnlX1RW9Z15SD4mp87vT2D2shsk0hpLJwSPcq3g=
 github.com/livekit/mediatransportutil v0.0.0-20250519131108-fb90f5acfded/go.mod h1:mSNtYzSf6iY9xM3UX42VEI+STHvMgHmrYzEHPcdhB8A=
-github.com/livekit/protocol v1.39.4-0.20250725083335-7313a8195a4b h1:uxvoeGd0vmGDIL0JyLLV9h2o97tpt3rR9s4ikuLVz/g=
-github.com/livekit/protocol v1.39.4-0.20250725083335-7313a8195a4b/go.mod h1:YlgUxAegtU8jZ0tVXoIV/4fHeHqqLvS+6JnPKDbpFPU=
+github.com/livekit/protocol v1.39.4-0.20250729112356-c072a903cb08 h1:A1g6uvZrEwKvaMpjIRkAdGry3PPPopM6kQniq7GlaRM=
+github.com/livekit/protocol v1.39.4-0.20250729112356-c072a903cb08/go.mod h1:YlgUxAegtU8jZ0tVXoIV/4fHeHqqLvS+6JnPKDbpFPU=
 github.com/livekit/psrpc v0.6.1-0.20250724161801-262a822e7cd7 h1:x50axcjXwfwnII7sMhJPyZ6f5LpPapZtsp75KJX8nIQ=
 github.com/livekit/psrpc v0.6.1-0.20250724161801-262a822e7cd7/go.mod h1:kmD+AZPkWu0MaXIMv57jhNlbiSZZ/Jx4bzlxBDVmJes=
 github.com/magefile/mage v1.15.0 h1:BvGheCMAsG3bWUDbZ8AyXXpCNwU9u5CB6sM+HNb9HYg=