diff --git a/.changeset/data-packet-sender-identity.md b/.changeset/data-packet-sender-identity.md
new file mode 100644
index 000000000..1a719425d
--- /dev/null
+++ b/.changeset/data-packet-sender-identity.md
@@ -0,0 +1,6 @@
+---
+"github.com/livekit/protocol": patch
+"@livekit/protocol": patch
+---
+
+Add a `sender` oneof (`sender_identity` / `sender_hidden`) to `DataPacket`, which the SFU sets to the real sender when an agent sends a packet on behalf of another participant
diff --git a/livekit/livekit_models.pb.go b/livekit/livekit_models.pb.go
index 8c5ffd328..6a50cea3e 100644
--- a/livekit/livekit_models.pb.go
+++ b/livekit/livekit_models.pb.go
@@ -3493,8 +3493,18 @@ type DataPacket struct {
 	Sequence uint32 `protobuf:"varint,16,opt,name=sequence,proto3" json:"sequence,omitempty"`
 	// sid of the user that sent the message
 	ParticipantSid string `protobuf:"bytes,17,opt,name=participant_sid,json=participantSid,proto3" json:"participant_sid,omitempty"`
-	unknownFields  protoimpl.UnknownFields
-	sizeCache      protoimpl.SizeCache
+	// The participant that actually sent this packet, when `participant_identity` names a different
+	// participant (an agent sending a text stream or chat message on behalf of another participant).
+	// Set only by the SFU, which clears any value a client sends; unset when `participant_identity` is
+	// the real sender. Available from server protocol 20.
+	//
+	// Types that are valid to be assigned to Sender:
+	//
+	//	*DataPacket_SenderIdentity
+	//	*DataPacket_SenderHidden
+	Sender        isDataPacket_Sender `protobuf_oneof:"sender"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
 }
 
 func (x *DataPacket) Reset() {
@@ -3688,6 +3698,31 @@ func (x *DataPacket) GetParticipantSid() string {
 	return ""
 }
 
+func (x *DataPacket) GetSender() isDataPacket_Sender {
+	if x != nil {
+		return x.Sender
+	}
+	return nil
+}
+
+func (x *DataPacket) GetSenderIdentity() string {
+	if x != nil {
+		if x, ok := x.Sender.(*DataPacket_SenderIdentity); ok {
+			return x.SenderIdentity
+		}
+	}
+	return ""
+}
+
+func (x *DataPacket) GetSenderHidden() bool {
+	if x != nil {
+		if x, ok := x.Sender.(*DataPacket_SenderHidden); ok {
+			return x.SenderHidden
+		}
+	}
+	return false
+}
+
 type isDataPacket_Value interface {
 	isDataPacket_Value()
 }
@@ -3771,6 +3806,25 @@ func (*DataPacket_StreamTrailer) isDataPacket_Value() {}
 
 func (*DataPacket_EncryptedPacket) isDataPacket_Value() {}
 
+type isDataPacket_Sender interface {
+	isDataPacket_Sender()
+}
+
+type DataPacket_SenderIdentity struct {
+	// identity of the participant that actually sent this packet
+	SenderIdentity string `protobuf:"bytes,19,opt,name=sender_identity,json=senderIdentity,proto3,oneof"`
+}
+
+type DataPacket_SenderHidden struct {
+	// the participant that actually sent this packet is hidden, so its identity is withheld; only
+	// ever true
+	SenderHidden bool `protobuf:"varint,20,opt,name=sender_hidden,json=senderHidden,proto3,oneof"`
+}
+
+func (*DataPacket_SenderIdentity) isDataPacket_Sender() {}
+
+func (*DataPacket_SenderHidden) isDataPacket_Sender() {}
+
 type EncryptedPacket struct {
 	state          protoimpl.MessageState `protogen:"open.v1"`
 	EncryptionType Encryption_Type        `protobuf:"varint,1,opt,name=encryption_type,json=encryptionType,proto3,enum=livekit.Encryption_Type" json:"encryption_type,omitempty"`
@@ -7182,7 +7236,7 @@ const file_livekit_models_proto_rawDesc = "" +
 	"\vMODE_UNUSED\x10\x00\x12 \n" +
 	"\x1cONE_SPATIAL_LAYER_PER_STREAM\x10\x01\x12&\n" +
 	"\"MULTIPLE_SPATIAL_LAYERS_PER_STREAM\x10\x02\x123\n" +
-	"/ONE_SPATIAL_LAYER_PER_STREAM_INCOMPLETE_RTCP_SR\x10\x03\"\x8c\b\n" +
+	"/ONE_SPATIAL_LAYER_PER_STREAM_INCOMPLETE_RTCP_SR\x10\x03\"\xe8\b\n" +
 	"\n" +
 	"DataPacket\x120\n" +
 	"\x04kind\x18\x01 \x01(\x0e2\x18.livekit.DataPacket.KindB\x02\x18\x01R\x04kind\x121\n" +
@@ -7204,11 +7258,14 @@ const file_livekit_models_proto_rawDesc = "" +
 	"\x0estream_trailer\x18\x0f \x01(\v2\x1b.livekit.DataStream.TrailerH\x00R\rstreamTrailer\x12E\n" +
 	"\x10encrypted_packet\x18\x12 \x01(\v2\x18.livekit.EncryptedPacketH\x00R\x0fencryptedPacket\x12\x1a\n" +
 	"\bsequence\x18\x10 \x01(\rR\bsequence\x12'\n" +
-	"\x0fparticipant_sid\x18\x11 \x01(\tR\x0eparticipantSid\"\x1f\n" +
+	"\x0fparticipant_sid\x18\x11 \x01(\tR\x0eparticipantSid\x12)\n" +
+	"\x0fsender_identity\x18\x13 \x01(\tH\x01R\x0esenderIdentity\x12%\n" +
+	"\rsender_hidden\x18\x14 \x01(\bH\x01R\fsenderHidden\"\x1f\n" +
 	"\x04Kind\x12\f\n" +
 	"\bRELIABLE\x10\x00\x12\t\n" +
 	"\x05LOSSY\x10\x01B\a\n" +
-	"\x05value\"\xaa\x01\n" +
+	"\x05valueB\b\n" +
+	"\x06sender\"\xaa\x01\n" +
 	"\x0fEncryptedPacket\x12A\n" +
 	"\x0fencryption_type\x18\x01 \x01(\x0e2\x18.livekit.Encryption.TypeR\x0eencryptionType\x12\x0e\n" +
 	"\x02iv\x18\x02 \x01(\fR\x02iv\x12\x1b\n" +
@@ -7917,6 +7974,8 @@ func file_livekit_models_proto_init() {
 		(*DataPacket_StreamChunk)(nil),
 		(*DataPacket_StreamTrailer)(nil),
 		(*DataPacket_EncryptedPacket)(nil),
+		(*DataPacket_SenderIdentity)(nil),
+		(*DataPacket_SenderHidden)(nil),
 	}
 	file_livekit_models_proto_msgTypes[22].OneofWrappers = []any{
 		(*EncryptedPacketPayload_User)(nil),
diff --git a/protobufs/livekit_models.proto b/protobufs/livekit_models.proto
index 1e681696b..eb554041b 100644
--- a/protobufs/livekit_models.proto
+++ b/protobufs/livekit_models.proto
@@ -471,7 +471,19 @@ message DataPacket {
   // sid of the user that sent the message
   string participant_sid = 17;
 
-  // NEXT_ID: 19
+  // The participant that actually sent this packet, when `participant_identity` names a different
+  // participant (an agent sending a text stream or chat message on behalf of another participant).
+  // Set only by the SFU, which clears any value a client sends; unset when `participant_identity` is
+  // the real sender. Available from server protocol 20.
+  oneof sender {
+    // identity of the participant that actually sent this packet
+    string sender_identity = 19;
+    // the participant that actually sent this packet is hidden, so its identity is withheld; only
+    // ever true
+    bool sender_hidden = 20;
+  }
+
+  // NEXT_ID: 21
 }
 
 message EncryptedPacket {