fix: backfill issue

Author: zxch3n

packages/loro-websocket/src/client/index.ts

@@ -534,7 +534,7 @@ export class LoroWebsocketClient {
           active.handler.handleDocUpdate(msg.updates);
         } else {
           const pending = this.pendingRooms.get(roomId);
-          if (pending && pending.adaptor.crdtType === CrdtType.Elo) {
+          if (pending) {
             const buf = this.preJoinUpdates.get(roomId) ?? [];
             buf.push(...msg.updates);
             this.preJoinUpdates.set(roomId, buf);
@@ -651,7 +651,7 @@ export class LoroWebsocketClient {
         active.handler.handleDocUpdate([reassembledData]);
       } else {
         const pending = this.pendingRooms.get(id);
-        if (pending && pending.adaptor.crdtType === CrdtType.Elo) {
+        if (pending) {
           const buf = this.preJoinUpdates.get(id) ?? [];
           buf.push(reassembledData);
           this.preJoinUpdates.set(id, buf);
@@ -672,7 +672,7 @@ export class LoroWebsocketClient {
     this.roomAdaptors.set(id, adaptor);
     this.roomIds.set(id, roomId);
 
-    // Flush buffered %ELO updates if any
+    // Flush buffered updates if any
     const buf = this.preJoinUpdates.get(id);
     if (buf && buf.length) {
       try {

packages/loro-websocket/src/server/crdt-doc.ts

@@ -27,7 +27,7 @@ const defaultDescriptors: ServerAdaptorDescriptor[] = [
   {
     adaptor: new LoroServerAdaptor(),
     shouldPersist: true,
-    allowBackfillWhenNoOtherClients: false,
+    allowBackfillWhenNoOtherClients: true,
   },
   {
     adaptor: new LoroEphemeralServerAdaptor(),

packages/loro-websocket/src/server/simple-server.ts

@@ -330,14 +330,12 @@ export class SimpleServer {
         joinResult.updates.length;
 
       if (shouldBackfill && joinResult.updates) {
-        for (const u of joinResult.updates) {
-          this.sendMessage(client.ws, {
-            type: MessageType.DocUpdate,
-            crdt: message.crdt,
-            roomId: message.roomId,
-            updates: [u],
-          });
-        }
+        this.sendMessage(client.ws, {
+          type: MessageType.DocUpdate,
+          crdt: message.crdt,
+          roomId: message.roomId,
+          updates: joinResult.updates
+        });
       }
     } catch (error) {
       this.sendJoinError(