diff --git a/.changeset/participant-update-full-snapshot.md b/.changeset/participant-update-full-snapshot.md
new file mode 100644
index 000000000..67cf0cdda
--- /dev/null
+++ b/.changeset/participant-update-full-snapshot.md
@@ -0,0 +1,5 @@
+---
+"@livekit/protocol": patch
+---
+
+Add `full_snapshot` to `ParticipantUpdate`, set when the message lists every visible participant so clients can drop remote participants that are missing from it
diff --git a/livekit/livekit_rtc.pb.go b/livekit/livekit_rtc.pb.go
index e5f3228f1..b54c824d3 100644
--- a/livekit/livekit_rtc.pb.go
+++ b/livekit/livekit_rtc.pb.go
@@ -2420,8 +2420,12 @@ func (x *SessionDescription) GetMidToTrackId() map[string]string {
 }
 
 type ParticipantUpdate struct {
-	state         protoimpl.MessageState `protogen:"open.v1"`
-	Participants  []*ParticipantInfo     `protobuf:"bytes,1,rep,name=participants,proto3" json:"participants,omitempty"`
+	state        protoimpl.MessageState `protogen:"open.v1"`
+	Participants []*ParticipantInfo     `protobuf:"bytes,1,rep,name=participants,proto3" json:"participants,omitempty"`
+	// when set, `participants` holds every participant visible to the receiver (the receiver itself
+	// included, hidden participants excluded) at the time the server built the message: the receiver
+	// drops any remote participant that is not listed. Unset for incremental updates.
+	FullSnapshot  bool `protobuf:"varint,2,opt,name=full_snapshot,json=fullSnapshot,proto3" json:"full_snapshot,omitempty"`
 	unknownFields protoimpl.UnknownFields
 	sizeCache     protoimpl.SizeCache
 }
@@ -2463,6 +2467,13 @@ func (x *ParticipantUpdate) GetParticipants() []*ParticipantInfo {
 	return nil
 }
 
+func (x *ParticipantUpdate) GetFullSnapshot() bool {
+	if x != nil {
+		return x.FullSnapshot
+	}
+	return false
+}
+
 type UpdateSubscription struct {
 	state             protoimpl.MessageState `protogen:"open.v1"`
 	TrackSids         []string               `protobuf:"bytes,1,rep,name=track_sids,json=trackSids,proto3" json:"track_sids,omitempty"`
@@ -5550,9 +5561,10 @@ const file_livekit_rtc_proto_rawDesc = "" +
 	"\x0fmid_to_track_id\x18\x04 \x03(\v2-.livekit.SessionDescription.MidToTrackIdEntryB\x0f\xbaP\fmidToTrackIDR\fmidToTrackId\x1a?\n" +
 	"\x11MidToTrackIdEntry\x12\x10\n" +
 	"\x03key\x18\x01 \x01(\tR\x03key\x12\x14\n" +
-	"\x05value\x18\x02 \x01(\tR\x05value:\x028\x01\"Q\n" +
+	"\x05value\x18\x02 \x01(\tR\x05value:\x028\x01\"v\n" +
 	"\x11ParticipantUpdate\x12<\n" +
-	"\fparticipants\x18\x01 \x03(\v2\x18.livekit.ParticipantInfoR\fparticipants\"\x9c\x01\n" +
+	"\fparticipants\x18\x01 \x03(\v2\x18.livekit.ParticipantInfoR\fparticipants\x12#\n" +
+	"\rfull_snapshot\x18\x02 \x01(\bR\ffullSnapshot\"\x9c\x01\n" +
 	"\x12UpdateSubscription\x12\x1d\n" +
 	"\n" +
 	"track_sids\x18\x01 \x03(\tR\ttrackSids\x12\x1c\n" +
diff --git a/protobufs/livekit_rtc.proto b/protobufs/livekit_rtc.proto
index cdcaf1955..a7302ca93 100644
--- a/protobufs/livekit_rtc.proto
+++ b/protobufs/livekit_rtc.proto
@@ -293,6 +293,10 @@ message SessionDescription {
 
 message ParticipantUpdate {
   repeated ParticipantInfo participants = 1;
+  // when set, `participants` holds every participant visible to the receiver (the receiver itself
+  // included, hidden participants excluded) at the time the server built the message: the receiver
+  // drops any remote participant that is not listed. Unset for incremental updates.
+  bool full_snapshot = 2;
 }
 
 message UpdateSubscription {