diff --git a/tools/chatgui/transport/chat_core.c b/tools/chatgui/transport/chat_core.c
index a310e741..a71adec5 100644
--- a/tools/chatgui/transport/chat_core.c
+++ b/tools/chatgui/transport/chat_core.c
@@ -1047,7 +1047,7 @@ static void on_db_sync_insert(struct DB_SYNC_INSTANCE* si, const char* data, siz
     if (rc==SQLITE_DONE) {
         uint8_t evt[65]; uint8_t cl=(uint8_t)strlen(ch_id); evt[0]=cl; memcpy(evt+1,ch_id,cl);
         gui_bridge_post(GUI_EVT_MSG_RECEIVED, evt, 1+cl);
-        chat_sync_push(g_cc.inst, ch_id, jn, jct, (const uint8_t*)jd_start, (uint32_t)jd_len, ts, dh);
+        chat_sync_push(g_cc.inst, ch_id, jn, jct, (const uint8_t*)jd_start, (uint32_t)jd_len, ts, dh, chain_h);
     } else if (rc == SQLITE_CONSTRAINT) {
         DEBUG_WARN(DEBUG_CATEGORY_CONNECTIVITY, "%s: on_db_sync_insert duplicate ch=%s ts=%lld dh=0x%016llx",
                    CC_ID, ch_id, (long long)ts, (unsigned long long)dh);
diff --git a/tools/chatgui/transport/chat_sync.c b/tools/chatgui/transport/chat_sync.c
index 55401b90..edbc91e6 100644
--- a/tools/chatgui/transport/chat_sync.c
+++ b/tools/chatgui/transport/chat_sync.c
@@ -625,7 +625,8 @@ void chat_sync_destroy(struct UTUN_INSTANCE* inst) {
 int chat_sync_push(struct UTUN_INSTANCE* inst,
                     const char* ch_id, uint64_t node_id,
                     const char* content_type, const uint8_t* data, uint32_t data_len,
-                    uint64_t timestamp, uint64_t datahash) {
+                    uint64_t timestamp, uint64_t datahash,
+                    const uint8_t* chain_hash) {
     if (!g_cs || !g_cs->initialized) return -1;
     struct channel_cache* ch = cs_find(g_cs, ch_id);
 
@@ -652,7 +653,7 @@ int chat_sync_push(struct UTUN_INSTANCE* inst,
     uint32_t dlen = data_len;
     memcpy(p, &dlen, 4); p += 4;
     if (data_len) { memcpy(p, data, data_len); p += data_len; }
-    memset(p, 0, 32); p += 32;
+    memcpy(p, chain_hash ? chain_hash : (const uint8_t*)"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 32); p += 32;
 
     int sent = 0;
     uint64_t myid = g_cs->inst->node_id;
@@ -1012,6 +1013,11 @@ static void cs_handle_channel_join(struct chat_sync* cs, uint64_t peer,
     { uint8_t evt[65]; uint8_t cl=(uint8_t)strlen(ch_id); evt[0]=cl; memcpy(evt+1,ch_id,cl);
       gui_bridge_post(GUI_EVT_MEMBERS_CHANGED, evt, 1+cl); }
 
+    /* initiate member sync with the joiner (server side) */
+    member_sync_start(cs->inst, node_id, ch_id, NULL, NULL);
+    DEBUG_INFO(DEBUG_CATEGORY_CONNECTIVITY, "%s: JOIN starting member_sync with joiner node=0x%016llx ch=%s",
+               CS_ID, (unsigned long long)node_id, ch_id);
+
     DEBUG_INFO(DEBUG_CATEGORY_CONNECTIVITY, "%s: JOIN accepted node=0x%016llx ch=%s addrs=%d",
                CS_ID, (unsigned long long)node_id, ch_id, addr_cnt);
 }
@@ -1078,6 +1084,8 @@ static void cs_handle_welcome(struct chat_sync* cs, uint64_t peer,
             memcpy(msg + 1, &ch2->msg_count, 4);
             memcpy(msg + 5, ch2->last_chain_hash, 32);
             cs_send(cs, ch2->channel_id, peer, msg, 37);
+            DEBUG_INFO(DEBUG_CATEGORY_CONNECTIVITY, "%s: WELCOME starting member_sync with inviter node=0x%016llx ch=%s",
+                       CS_ID, (unsigned long long)peer, ch_id);
             member_sync_start(cs->inst, peer, ch2->channel_id, _on_member_sync_done, ch2);
         }
         break;
diff --git a/tools/chatgui/transport/chat_sync.h b/tools/chatgui/transport/chat_sync.h
index 077e520f..b31ff567 100644
--- a/tools/chatgui/transport/chat_sync.h
+++ b/tools/chatgui/transport/chat_sync.h
@@ -50,7 +50,8 @@ void chat_sync_destroy(struct UTUN_INSTANCE* inst);
 int  chat_sync_push(struct UTUN_INSTANCE* inst,
                     const char* channel_id, uint64_t node_id,
                     const char* content_type, const uint8_t* data, uint32_t data_len,
-                    uint64_t timestamp, uint64_t datahash);
+                    uint64_t timestamp, uint64_t datahash,
+                    const uint8_t* chain_hash);
 
 /* Прослойка conn_mgr: загрузить nodeinfo из БД и подключиться */
 void chat_sync_connect_node(struct UTUN_INSTANCE* inst, uint64_t node_id);