fix chatgui: db_sync_stub + chat_sync_init for invite link join

- db_sync_stub.c: complete rewrite — proper structs, all API functions
  (db_sync_instance_add, insert_signed, set_insert_cb, select)
  Fixes db_sync_instance_add returning NULL (inst->db_sync was NULL)
- libutun/CMakeLists.txt: remove src/db_sync.c, stub replaces it
- chatgui/CMakeLists.txt: add transport/db_sync_stub.c
- utun_node.cpp: remove redundant db_sync_init/destroy,
  add chat_sync_init/destroy — server now registers svc_id=48
  Fixes 'no handler for svc_id=48' on incoming CHANNEL_INFO_REQ

tools/chatgui/CMakeLists.txt

@@ -76,6 +76,7 @@ add_executable(chatgui
     transport/chat_sync.c
     transport/member_sync.c
     transport/merkle_sync.c
+    transport/db_sync_stub.c
     db/db_manager.cpp
     ../../lib/sqlite3.c
     resources/chatgui.qrc
@@ -83,7 +84,7 @@ add_executable(chatgui
 
 target_include_directories(chatgui PRIVATE ${CMAKE_SOURCE_DIR}/../../lib ${CMAKE_SOURCE_DIR}/../../src ${CMAKE_SOURCE_DIR}/db)
 target_compile_definitions(chatgui PRIVATE SQLITE_THREADSAFE=1 USE_SQLITE)
-set_source_files_properties(../../lib/sqlite3.c transport/chat_core.c transport/chat_sync.c transport/member_sync.c transport/merkle_sync.c PROPERTIES LANGUAGE C)
+set_source_files_properties(../../lib/sqlite3.c transport/chat_core.c transport/chat_sync.c transport/member_sync.c transport/merkle_sync.c transport/db_sync_stub.c PROPERTIES LANGUAGE C)
 if(WIN32)
     target_link_libraries(chatgui PRIVATE ${QT_LIBS} rlottie::rlottie ZLIB::ZLIB OpenSSL::Crypto ZXing::ZXing utun pthread)
 else()

tools/chatgui/libutun/CMakeLists.txt

@@ -62,7 +62,7 @@ set(UTUN_COMMON_SOURCES
     ${SRC_DIR}/topo_node.c
     ${SRC_DIR}/topo_node_sqlite.c
     ${SRC_DIR}/route_connectivity.c
-    ${SRC_DIR}/db_sync.c
+    # db_sync.c replaced by db_sync_stub.c (no P2P sync in chatgui)
     ${SRC_DIR}/conn_mgr.c
     ${TRANSPORT_DIR}/chat_sync.c
     ${TRANSPORT_DIR}/merkle_sync.c

tools/chatgui/transport/db_sync_stub.c

@@ -1,31 +1,154 @@
+// db_sync_stub.c — Minimal db_sync replacement for chatgui (no P2P sync, local only)
+//
+// Назначение: заменяет полноценный db_sync.c когда синхронизация через ETCP не нужна.
+// Сохраняет API-совместимость: chat_core.c использует db_sync_instance_add / db_sync_set_insert_cb /
+// db_sync_insert_signed — стаб обрабатывает их локально, без сетевого обмена.
+//
+// utun_instance.c вызывает db_sync_init/db_sync_destroy — стаб создаёт минимальную инфраструктуру
+// без SQLite и без регистрации ETCP-сервисов.
+
 #include "db_sync.h"
 #include "utun_instance.h"
-#include "../lib/u_async.h"
-#include "../lib/debug_config.h"
 #include "../lib/mem.h"
+#include "../lib/debug_config.h"
+#include <string.h>
+#include <stdlib.h>
+
+#define DEBUG_CATEGORY_DB_SYNC DEBUG_CATEGORY_DEBUG
+
+/* ── Internal structs (match db_sync.h opaque types) ── */
+
+struct DB_SYNC_INSTANCE {
+    struct DB_SYNC* db_sync;
+    uint8_t         enabled;
+    db_sync_insert_cb on_insert;
+    void*           on_insert_arg;
+};
+
+struct DB_SYNC {
+    struct UTUN_INSTANCE*      inst;
+    struct DB_SYNC_INSTANCE*   instances;
+    int                        instance_count, instance_capacity;
+    uint8_t                    enabled;
+};
+
+/* ── Init / Destroy ── */
 
 int db_sync_init(struct UTUN_INSTANCE* inst) {
-    (void)inst;
+    if (!inst) {
-    DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "db_sync: stub (disabled for chatgui)");
+        DEBUG_ERROR(DEBUG_CATEGORY_DB_SYNC, "db_sync stub: NULL instance");
+        return -1;
+    }
+    if (inst->db_sync) {
+        DEBUG_INFO(DEBUG_CATEGORY_DB_SYNC, "db_sync stub: already initialized");
+        return 0;
+    }
+    struct DB_SYNC* db = u_calloc(1, sizeof(struct DB_SYNC));
+    if (!db) {
+        DEBUG_ERROR(DEBUG_CATEGORY_DB_SYNC, "db_sync stub: u_calloc failed");
+        return -1;
+    }
+    db->inst = inst;
+    db->enabled = 1;
+    db->instance_count = 0;
+    db->instance_capacity = 0;
+    db->instances = NULL;
+    inst->db_sync = db;
+    DEBUG_INFO(DEBUG_CATEGORY_DB_SYNC, "db_sync: stub initialized (local-only, no P2P sync)");
     return 0;
 }
 
 void db_sync_destroy(struct UTUN_INSTANCE* inst) {
-    (void)inst;
+    if (!inst || !inst->db_sync) return;
-    DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "db_sync: stub destroyed");
+    struct DB_SYNC* db = inst->db_sync;
+    inst->db_sync = NULL;
+    for (int i = 0; i < db->instance_count; i++) {
+        struct DB_SYNC_INSTANCE* si = &db->instances[i];
+        if (si->on_insert_arg) u_free(si->on_insert_arg);
+    }
+    if (db->instances) u_free(db->instances);
+    u_free(db);
+    DEBUG_INFO(DEBUG_CATEGORY_DB_SYNC, "db_sync: stub destroyed");
+}
+
+/* ── Instance management ── */
+
+struct DB_SYNC_INSTANCE* db_sync_instance_add(struct UTUN_INSTANCE* inst,
+                                               const char* name, uint64_t id) {
+    if (!inst || !inst->db_sync || !name || !name[0]) {
+        DEBUG_ERROR(DEBUG_CATEGORY_DB_SYNC, "db_sync stub: instance_add invalid args");
+        return NULL;
+    }
+    struct DB_SYNC* db = inst->db_sync;
+
+    if (db->instance_count >= db->instance_capacity) {
+        int nc = db->instance_capacity ? db->instance_capacity * 2 : 4;
+        struct DB_SYNC_INSTANCE* np = u_realloc(db->instances, nc * sizeof(*db->instances));
+        if (!np) return NULL;
+        db->instances = np;
+        db->instance_capacity = nc;
+    }
+    struct DB_SYNC_INSTANCE* si = &db->instances[db->instance_count++];
+    memset(si, 0, sizeof(*si));
+    si->db_sync = db;
+    si->enabled = 1;
+    DEBUG_INFO(DEBUG_CATEGORY_DB_SYNC, "db_sync stub: instance added name=%s id=0x%016llx idx=%d",
+               name, (unsigned long long)id, db->instance_count - 1);
+    return si;
+}
+
+void db_sync_instance_remove(struct DB_SYNC_INSTANCE* si) {
+    if (!si) return;
+    struct DB_SYNC* db = si->db_sync;
+    si->enabled = 0;
+    if (si->on_insert_arg) { u_free(si->on_insert_arg); si->on_insert_arg = NULL; }
+    int idx = (int)(si - db->instances);
+    if (idx >= 0 && idx < db->instance_count) {
+        memmove(&db->instances[idx], &db->instances[idx + 1],
+                (db->instance_count - idx - 1) * sizeof(*db->instances));
+        db->instance_count--;
+    }
+    DEBUG_INFO(DEBUG_CATEGORY_DB_SYNC, "db_sync stub: instance removed idx=%d", idx);
 }
 
-int db_sync_insert_len(struct UTUN_INSTANCE* inst, const char* json_data, size_t len) {
+/* ── Insert ── */
-    (void)inst; (void)json_data; (void)len;
+
+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;
+    if (si->on_insert)
+        si->on_insert(si, json_data, len, si->db_sync->inst->node_id, si->on_insert_arg);
     return 0;
 }
 
-int db_sync_insert(struct UTUN_INSTANCE* inst, const char* json_data) {
+int db_sync_insert_len(struct DB_SYNC_INSTANCE* si, const char* json_data, size_t len) {
-    (void)inst; (void)json_data;
+    return db_sync_insert_signed(si, json_data, len, NULL, 0);
+}
+
+int db_sync_insert(struct DB_SYNC_INSTANCE* si, const char* json_data) {
+    if (!json_data) return -1;
+    return db_sync_insert_len(si, json_data, strlen(json_data));
+}
+
+/* ── Count / Select ── */
+
+uint32_t db_sync_count(struct DB_SYNC_INSTANCE* si) {
+    (void)si;
     return 0;
 }
 
-uint32_t db_sync_count(struct UTUN_INSTANCE* inst) {
+int db_sync_select(struct DB_SYNC_INSTANCE* si, uint32_t offset, uint32_t limit,
-    (void)inst;
+                    db_sync_select_cb cb, void* arg) {
+    (void)si; (void)offset; (void)limit; (void)cb; (void)arg;
     return 0;
 }
+
+/* ── Callbacks ── */
+
+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;
+    if (si->on_insert_arg) u_free(si->on_insert_arg);
+    si->on_insert_arg = arg;
+}

tools/chatgui/transport/utun_node.cpp

@@ -238,10 +238,10 @@ void UtunNode::runLoop() {
 
     etcp_router_bind(m_instance, ETCP_RT_ID_CHAT, recvCallback);
 
-    /* Initialize chat_core (DB) and db_sync (message sync) */
+    /* Initialize chat_core (DB) and chat_sync (channel/message P2P sync) */
     chat_core_init(m_instance, m_dbPath.toUtf8().constData());
-    db_sync_init(m_instance);
+    chat_sync_init(m_instance, nullptr);
-    DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "chat_core + db_sync initialized");
+    DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "chat_core + chat_sync initialized");
     DEBUG_INFO(DEBUG_CATEGORY_DEBUG, "utun_node: entering poll loop");
 
     while (!m_stop) {
@@ -249,7 +249,7 @@ void UtunNode::runLoop() {
     }
 
     etcp_router_bind(m_instance, ETCP_RT_ID_CHAT, nullptr);
-    db_sync_destroy(m_instance);
+    chat_sync_destroy(m_instance);
     chat_core_destroy(m_instance);
     utun_instance_destroy(m_instance);
     m_instance = nullptr;