fix: wall-clock timestamps + merkle_sync timeout + build script

- Replace get_time_us() with utun_gettimeofday() for PUSH message timestamps
  (db_sync.c, chat_core.c) — monotonic clocks differ across Linux/Windows
- Fix merkle_sync: restart session timer in _handle_request to prevent
  double-sided timeout when both nodes start member_sync simultaneously
- Fix INIT_RESP short-format: don't mark synced when my_count > peer_count
- Add db_sync_get_last_timestamp() to avoid duplicate timestamp generation
  between db_sync and chat_core on_db_sync_insert
- Fix db_sync_stub to generate timestamps consistently
- build.sh: auto-rebuild chatgui via CMake after utun build

build.sh

@@ -180,6 +180,15 @@ if [ $BUILD_SUCCESS -eq 1 ]; then
     echo ""
     echo "Build completed successfully!"
     echo "Binary: utun"
+
+    # Rebuild chatgui (CMake project) if transport sources changed
+    if [ -f tools/chatgui/build/CMakeCache.txt ] && command -v cmake &> /dev/null; then
+        echo ""
+        echo "======================================"
+        echo "Rebuilding chatgui (CMake)"
+        echo "======================================"
+        (cd tools/chatgui/build && cmake --build . -j4 2>&1) || echo "WARNING: chatgui build failed"
+    fi
 else
     echo ""
     echo "ERROR: Build failed!"

src/db_sync.c

@@ -351,7 +351,9 @@ int db_sync_insert_len(struct DB_SYNC_INSTANCE* si, const char* json_data, size_
 
 int db_sync_insert_signed(struct DB_SYNC_INSTANCE* si, const char* json_data, size_t len, const uint8_t* sig, size_t sig_len) {
     if (!si||!si->enabled||!json_data||len==0) { DEBUG_ERROR(DEBUG_CATEGORY_DB_SYNC,"insert invalid args"); return -1; }
-    uint64_t dh=db_datahash((const uint8_t*)json_data,len), nu=get_time_us(); if (nu<=si->last_timestamp_us) nu=si->last_timestamp_us+1; si->last_timestamp_us=nu; uint64_t ts=nu, id=si->next_id;
+    struct timeval tv; utun_gettimeofday(&tv, NULL); uint64_t nu=(uint64_t)tv.tv_sec*1000000ULL+(uint64_t)tv.tv_usec;
+    if (nu<=si->last_timestamp_us) nu=si->last_timestamp_us+1; si->last_timestamp_us=nu;
+    uint64_t dh=db_datahash((const uint8_t*)json_data,len), ts=nu, id=si->next_id;
     int ret=db_record_insert(si,id,ts,dh,json_data,len,sig,sig_len); if (ret!=0) return ret;
     if (si->on_insert) si->on_insert(si,json_data,len,si->db_sync->inst->node_id,si->on_insert_arg);
     // Build PUSH: [DB_MSG_PUSH][id:8][ts:8][dh:8][dlen:4][data][sig_len:1][sig]
@@ -370,6 +372,8 @@ uint32_t db_sync_count(struct DB_SYNC_INSTANCE* si) { if (!si||!si->enabled) ret
 
 void db_sync_set_insert_cb(struct DB_SYNC_INSTANCE* si, db_sync_insert_cb cb, void* arg) { if (!si) return; si->on_insert=cb; si->on_insert_arg=arg; }
 
+uint64_t db_sync_get_last_timestamp(struct DB_SYNC_INSTANCE* si) { return si ? si->last_timestamp_us : 0; }
+
 int db_sync_select(struct DB_SYNC_INSTANCE* si, uint32_t offset, uint32_t limit, db_sync_select_cb cb, void* arg) {
     if (!si||!si->enabled||!cb) return 0; sqlite3_stmt* stmt;
     if (si_prep(si,&stmt,"SELECT id,timestamp,author,data,author_signature,delivered_peers,delivery_chain FROM \"%s\" ORDER BY timestamp,datahash LIMIT ? OFFSET ?")!=SQLITE_OK) return 0;

src/db_sync.h

@@ -85,6 +85,7 @@ int      db_sync_insert(struct DB_SYNC_INSTANCE* si, const char* json_data);
 int      db_sync_insert_signed(struct DB_SYNC_INSTANCE* si, const char* json_data, size_t len,
                                const uint8_t* sig, size_t sig_len);
 uint32_t db_sync_count(struct DB_SYNC_INSTANCE* si);
+uint64_t db_sync_get_last_timestamp(struct DB_SYNC_INSTANCE* si);
 
 // Select: iterate records ordered by (timestamp, datahash), starting at offset, max limit (0=unlimited).
 // Returns number of records passed to callback.

tools/chatgui/transport/chat_core.c

@@ -1025,7 +1025,7 @@ static void on_db_sync_insert(struct DB_SYNC_INSTANCE* si, const char* data, siz
     if (!jd_start) { DEBUG_ERROR(DEBUG_CATEGORY_CONNECTIVITY, "%s: on_db_sync_insert JSON parse fail: no '\"d\"' field ch=%s", CC_ID, ch_id); return; }
 
     uint64_t dh; compute_datahash((const uint8_t*)jd_start, jd_len, &dh);
-    uint64_t ts = get_time_us();
+    uint64_t ts = db_sync_get_last_timestamp(si);
     char tbl[80]; msg_table_name(ch_id, tbl, sizeof(tbl));
     uint8_t prev_ch[32]; get_last_chain_hash(ch_id, prev_ch);
     uint8_t chain_h[32]; compute_chain_hash(prev_ch, (int64_t)ts, dh, chain_h);

tools/chatgui/transport/chat_sync.c

@@ -189,9 +189,12 @@ static void cs_handle_init_resp(struct chat_sync* cs, uint64_t peer,
         cs_send(cs, ch_id, peer, snd, 7);
         DEBUG_INFO(DEBUG_CATEGORY_CONNECTIVITY, "%s: INIT_RESP peer ahead (peer=%u my=%u), request from=%u",
                    CS_ID, peer_count, my_count, from);
-    } else {
+    } else if (peer_count == my_count) {
         if (ch) ch->synced = CS_SYNC_DONE;
-        DEBUG_INFO(DEBUG_CATEGORY_CONNECTIVITY, "%s: INIT_RESP synced (peer=%u <= my=%u)",
+        DEBUG_INFO(DEBUG_CATEGORY_CONNECTIVITY, "%s: INIT_RESP synced (peer=%u == my=%u)",
+                   CS_ID, peer_count, my_count);
+    } else {
+        DEBUG_INFO(DEBUG_CATEGORY_CONNECTIVITY, "%s: INIT_RESP peer behind (peer=%u < my=%u), waiting for peer SEND_DATA",
                    CS_ID, peer_count, my_count);
     }
 }

tools/chatgui/transport/db_sync_stub.c

@@ -21,6 +21,7 @@
 struct DB_SYNC_INSTANCE {
     struct DB_SYNC* db_sync;
     uint8_t         enabled;
+    uint64_t        last_timestamp_us;
     db_sync_insert_cb on_insert;
     void*           on_insert_arg;
 };
@@ -117,6 +118,8 @@ int db_sync_insert_signed(struct DB_SYNC_INSTANCE* si, const char* json_data,
                            size_t len, const uint8_t* sig, size_t sig_len) {
     (void)sig; (void)sig_len;
     if (!si || !si->enabled || !json_data || len == 0) return -1;
+    struct timeval tv; utun_gettimeofday(&tv, NULL);
+    si->last_timestamp_us = (uint64_t)tv.tv_sec * 1000000ULL + (uint64_t)tv.tv_usec;
     if (si->on_insert)
         si->on_insert(si, json_data, len, si->db_sync->inst->node_id, si->on_insert_arg);
     return 0;
@@ -152,3 +155,8 @@ void db_sync_set_insert_cb(struct DB_SYNC_INSTANCE* si, db_sync_insert_cb cb, vo
     if (si->on_insert_arg) u_free(si->on_insert_arg);
     si->on_insert_arg = arg;
 }
+
+uint64_t db_sync_get_last_timestamp(struct DB_SYNC_INSTANCE* si) {
+    if (!si) return 0;
+    return si->last_timestamp_us;
+}

tools/chatgui/transport/merkle_sync.c

@@ -417,7 +417,14 @@ static void _handle_request(struct merkle_sync* ms, uint64_t peer, const char* n
         buckets[bc].level = lvl; buckets[bc].prefix_bytes = pb_i; buckets[bc].prefix = pr; bc++;
         off++; /* skip is_terminal byte */
     }
-    if (bc > 0) _send_batch(ms, peer, ns, buckets, bc);
+    if (bc > 0) {
+        _send_batch(ms, peer, ns, buckets, bc);
+        struct ms_session* s = _session_find(ms, peer, ns);
+        if (s && s->active) {
+            if (s->timer) { uasync_cancel_timeout(ms->inst->ua, s->timer); s->timer = NULL; }
+            _session_start_timer(s);
+        }
+    }
 }
 
 static void _handle_batch(struct merkle_sync* ms, uint64_t peer, const char* ns,