diff --git a/src/member_files/transfer.c b/src/member_files/transfer.c
index 08bc64f6..337328bd 100644
--- a/src/member_files/transfer.c
+++ b/src/member_files/transfer.c
@@ -63,6 +63,8 @@ static void transfer_finish(struct mf_transfer* t, int status) {
 
 static void transfer_work(void* arg) {
     struct mf_transfer* t = arg;
+    DEBUG_TRACE(DEBUG_CATEGORY_DEBUG, "member_files: local I/O start transfer=%llu work=%d fd=%d offset=%llu bytes=%u",
+        (unsigned long long)t->request.id, t->work, t->fd, (unsigned long long)t->offset, t->bytes);
     t->work_status = MF_OK;
     if (t->work == TRANSFER_PREPARE) {
         if (t->request.upload) {
@@ -113,6 +115,8 @@ static void transfer_release(struct mf_transfer* t) {
 
 static void transfer_done(void* arg, int error) {
     struct mf_transfer* t = arg; t->busy = 0;
+    DEBUG_DEBUG(DEBUG_CATEGORY_DEBUG, "member_files: local I/O done transfer=%llu work=%d status=%s error=%d cancelled=%d",
+        (unsigned long long)t->request.id, t->work, mf_status_text(t->work_status), error, t->cancelled);
     int status = error ? MF_CANCELLED : t->work_status;
     if (t->work == TRANSFER_FINISH) {
         /* При destroy work могла быть завершена, а completion отменён. fd уже закрыт. */
@@ -143,6 +147,9 @@ static void transfer_submit(struct mf_transfer* t, enum transfer_work work) {
 
 static void transfer_response(void* arg, const struct mf_message* r) {
     struct mf_transfer* t = arg; t->pending = NULL;
+    DEBUG_DEBUG(DEBUG_CATEGORY_DEBUG, "member_files: transfer response transfer=%llu request=%llu cmd=%s status=%s offset=%llu bytes=%u",
+        (unsigned long long)t->request.id, (unsigned long long)r->request_id, mf_command_text(r->command), mf_status_text(r->status),
+        (unsigned long long)r->offset, r->data_len);
     if (t->cancelled || t->files->closing || r->status) { transfer_finish(t, r->status ? r->status : MF_CANCELLED); return; }
     if (r->command == MF_STAT) {
         if (r->type != MF_FILE || r->size > INT64_MAX || mf_zero(r->version, 16)) { transfer_finish(t, MF_INVALID_RANGE); return; }
@@ -180,7 +187,7 @@ static void transfer_send(struct mf_transfer* t, uint8_t command) {
 static void transfer_connected(struct CONN_MGR_HANDLE* h, uint64_t peer, uint64_t group, enum conn_mgr_event event, void* arg) {
     (void)h; (void)peer; (void)group;
     struct mf_transfer* t = arg;
-    DEBUG_DEBUG(DEBUG_CATEGORY_MEDIA, "member_files: transfer CM id=%llu event=%d", (unsigned long long)t->request.id, event);
+    DEBUG_DEBUG(DEBUG_CATEGORY_DEBUG, "member_files: transfer CM id=%llu event=%d", (unsigned long long)t->request.id, event);
 }
 
 void member_files_gui_transfer(void* arg) {
@@ -215,6 +222,8 @@ void member_files_gui_transfer(void* arg) {
 static void transfer_cancel(struct mf_transfer* t) {
     if (t->cancelled || t->work == TRANSFER_FINISH) return;
     t->cancelled = 1; t->status = MF_CANCELLED;
+    DEBUG_DEBUG(DEBUG_CATEGORY_DEBUG, "member_files: transfer cancel id=%llu busy=%d pending=%p work=%d",
+                (unsigned long long)t->request.id, t->busy, (void*)t->pending, t->work);
     if (t->pending) member_files_cancel(t->pending);
     else if (!t->busy) transfer_finish(t, MF_CANCELLED);
 }
diff --git a/src/utun.c b/src/utun.c
index 2b42ecc7..871eab22 100644
--- a/src/utun.c
+++ b/src/utun.c
@@ -415,6 +415,8 @@ int main(int argc, char *argv[]) {
         uasync_destroy(ua, 0); main_ua = NULL;
         return 1;
     }
+    DEBUG_DEBUG(DEBUG_CATEGORY_DEBUG, "member_files startup: core initialized pid=%ld foreground=%d ua=%p files=%p",
+                (long)getpid(), args.foreground, (void*)ua, (void*)instance->member_files);
     
     // Note: TUN socket is registered in tun_init(), ETCP sockets in init_connections()
     
diff --git a/tools/chatgui/src/member_files/browser.cpp b/tools/chatgui/src/member_files/browser.cpp
index 7926f6c8..a84256e6 100644
--- a/tools/chatgui/src/member_files/browser.cpp
+++ b/tools/chatgui/src/member_files/browser.cpp
@@ -140,11 +140,18 @@ void MemberFileBrowser::updateActions() {
 }
 
 bool MemberFileBrowser::post(mf_message& message) {
-    if (!m_group || !server() || !gui_bridge_is_uasync_ready()) return false;
+    if (!m_group || !server() || !gui_bridge_is_uasync_ready()) {
+        DEBUG_DEBUG(DEBUG_CATEGORY_DEBUG, "member_files: GUI post rejected cmd=%s group=%llx server=%llx ready=%d",
+                    mf_command_text(message.command), (unsigned long long)m_group, (unsigned long long)server(), gui_bridge_is_uasync_ready());
+        return false;
+    }
     auto* q = (mf_gui_request*)u_calloc(1, sizeof(mf_gui_request));
     if (!q) { DEBUG_ERROR(DEBUG_CATEGORY_MEDIA, "file browser: request allocation failed"); return false; }
     message.request_id = requestId(); message.kind = MF_REQUEST;
     q->inst = gui_bridge_get_inst(); q->group = m_group; q->server = server(); q->message = message;
+    DEBUG_DEBUG(DEBUG_CATEGORY_DEBUG, "member_files: GUI post id=%llu cmd=%s group=%llx server=%llx owner=%llx path=%s",
+        (unsigned long long)message.request_id, mf_command_text(message.command), (unsigned long long)m_group,
+        (unsigned long long)server(), (unsigned long long)message.owner, message.path);
     gui_bridge_post_uasync_fn(member_files_gui_request, q); return true;
 }
 
@@ -156,6 +163,8 @@ void MemberFileBrowser::cancelRequest(quint64 id) {
 }
 
 void MemberFileBrowser::refresh() {
+    DEBUG_DEBUG(DEBUG_CATEGORY_DEBUG, "member_files: GUI refresh old_id=%llu group=%llx server=%llx owner=%llx path=%s",
+        (unsigned long long)m_listId, (unsigned long long)m_group, (unsigned long long)server(), (unsigned long long)owner(), qPrintable(m_path));
     cancelRequest(m_listId); m_listId = 0; m_entries->clear(); m_location->setText(m_path); updateActions();
     if (!server()) { m_status->setText(text("No media server in this group")); return; }
     mf_message q{}; q.command = MF_LIST; q.owner = owner();
@@ -180,8 +189,17 @@ void MemberFileBrowser::enter(QTreeWidgetItem* item) {
 }
 
 void MemberFileBrowser::onResponse(const uint8_t* data, int length) {
-    if (length < 16 || mf_get64(data) != m_group || mf_get64(data + 8) != server()) return;
+    if (!data || length < 16) { DEBUG_DEBUG(DEBUG_CATEGORY_DEBUG, "member_files: GUI short response bytes=%d", length); return; }
+    if (mf_get64(data) != m_group || mf_get64(data + 8) != server()) {
+        DEBUG_DEBUG(DEBUG_CATEGORY_DEBUG, "member_files: GUI response ignored context group=%llx/%llx server=%llx/%llx",
+            (unsigned long long)mf_get64(data), (unsigned long long)m_group,
+            (unsigned long long)mf_get64(data + 8), (unsigned long long)server());
+        return;
+    }
     mf_message r{}; if (mf_decode(data + 16, (size_t)length - 16, &r)) return;
+    DEBUG_DEBUG(DEBUG_CATEGORY_DEBUG, "member_files: GUI response id=%llu list_id=%llu cmd=%s status=%s bytes=%u owner=%llx/%llx path=%s",
+        (unsigned long long)r.request_id, (unsigned long long)m_listId, mf_command_text(r.command), mf_status_text(r.status), r.data_len,
+        (unsigned long long)r.owner, (unsigned long long)owner(), r.path);
     if (r.request_id == m_listId && r.owner == owner() && QString::fromUtf8(r.path) == m_path) {
         if (r.status) {
             m_listId = 0;
@@ -211,10 +229,16 @@ void MemberFileBrowser::onResponse(const uint8_t* data, int length) {
         } else {
             m_listId = 0; m_entries->setSortingEnabled(true); m_entries->sortItems(0, Qt::AscendingOrder);
             m_status->setText(text("%1 entries").arg(m_entries->topLevelItemCount())); updateActions();
+            DEBUG_DEBUG(DEBUG_CATEGORY_DEBUG, "member_files: GUI directory ready id=%llu entries=%d",
+                        (unsigned long long)r.request_id, m_entries->topLevelItemCount());
         }
         return;
     }
-    if (!m_actions.contains(r.request_id)) return;
+    if (!m_actions.contains(r.request_id)) {
+        DEBUG_DEBUG(DEBUG_CATEGORY_DEBUG, "member_files: GUI response ignored stale id=%llu cmd=%s",
+                    (unsigned long long)r.request_id, mf_command_text(r.command));
+        return;
+    }
     uint8_t command = m_actions.take(r.request_id);
     if (r.status && r.status != MF_CANCELLED) { QMessageBox::warning(this, text("Group files"), QString::fromUtf8(mf_status_text(r.status))); return; }
     if (command == MF_STAT && !r.status) {