diff --git a/src/Adapter.cc b/src/Adapter.cc
index 347aaed..1bb6c59 100644
--- a/src/Adapter.cc
+++ b/src/Adapter.cc
@@ -15,66 +15,10 @@ thread_local pEp::Adapter::Session pEp::Adapter::session{};
 
 namespace pEp {
     namespace Adapter {
-        std::thread _sync_thread;
-        ::utility::locked_queue<SYNC_EVENT, ::free_Sync_event> sync_evt_q;
-        std::mutex mut;
-
-        // private
-        std::thread::id sync_thread_id()
-        {
-            return _sync_thread.get_id();
-        }
-
-        // private
-        int _process_sync_event(::SYNC_EVENT ev, void *management)
-        {
-            if (ev != nullptr) {
-                ::do_sync_protocol_step(session(), nullptr, ev);
-            }
-            return 0;
-        }
-
-        // public (json adapter needs it, but should use Session mgmt from libpEpAdapter eventually)
-        int _inject_sync_event(::SYNC_EVENT ev, void *management)
-        {
-            try {
-                if (ev == nullptr) {
-                    sync_evt_q.clear();
-                    sync_evt_q.push_back(ev);
-                } else {
-                    sync_evt_q.push_front(ev);
-                }
-            } catch (exception &) {
-                return 1;
-            }
-            return 0;
-        }
-
-        // private
-        PEP_STATUS _ensure_passphrase(::PEP_SESSION session, const char *fpr)
-        {
-            return passphrase_cache.ensure_passphrase(session, fpr);
-        }
-
-        // public
-        ::SYNC_EVENT _retrieve_next_sync_event(void *management, unsigned threshold)
-        {
-            ::SYNC_EVENT syncEvent = nullptr;
-            const bool success = sync_evt_q.try_pop_front(syncEvent, std::chrono::seconds(threshold));
-
-            if (!success) {
-                return ::new_sync_timeout_event();
-            }
-
-            return syncEvent;
-        }
-
-        // public
-        bool on_sync_thread()
-        {
-            return _sync_thread.get_id() == this_thread::get_id();
-        }
+        ::SYNC_EVENT _cb_dequeue_next_sync_event(void *management, unsigned threshold);
 
+        // ---------------------------------------------------------------------------------------
+        // SESSION
         // ---------------------------------------------------------------------------------------
         Session::Session() :
             _sync_mode{ SyncModes::Async }, _messageToSend{ nullptr }, _notifyHandshake{ nullptr },
@@ -167,6 +111,62 @@ namespace pEp {
             return _session.get();
         }
 
+        // ---------------------------------------------------------------------------------------
+        // SYNC
+        // ---------------------------------------------------------------------------------------
+        std::thread _sync_thread{};
+        ::utility::locked_queue<SYNC_EVENT, ::free_Sync_event> sync_evt_q{};
+
+        // private
+        std::thread::id sync_thread_id()
+        {
+            return _sync_thread.get_id();
+        }
+
+        // private
+        int _cb_pass_sync_event_to_engine(::SYNC_EVENT ev, void *management)
+        {
+            if (ev != nullptr) {
+                ::do_sync_protocol_step(session(), nullptr, ev);
+            }
+            return 0;
+        }
+
+        // public (json adapter needs it, but should use Session mgmt from libpEpAdapter eventually)
+        int _cb_enqueue_sync_event(::SYNC_EVENT ev, void *management)
+        {
+            try {
+                if (ev == nullptr) {
+                    sync_evt_q.clear();
+                    sync_evt_q.push_back(ev);
+                } else {
+                    sync_evt_q.push_front(ev);
+                }
+            } catch (...) {
+                return 1;
+            }
+            return 0;
+        }
+
+        // public
+        ::SYNC_EVENT _cb_dequeue_next_sync_event(void *management, unsigned threshold)
+        {
+            ::SYNC_EVENT syncEvent = nullptr;
+            const bool success = sync_evt_q.try_pop_front(syncEvent, std::chrono::seconds(threshold));
+
+            if (!success) {
+                return ::new_sync_timeout_event();
+            }
+
+            return syncEvent;
+        }
+
+        // public
+        bool on_sync_thread()
+        {
+            return _sync_thread.get_id() == this_thread::get_id();
+        }
+
         // public
         void inject_sync_shutdown()
         {
@@ -214,6 +214,12 @@ namespace pEp {
             }
             return !ev;
         }
+
+        PEP_STATUS _ensure_passphrase(::PEP_SESSION session, const char *fpr)
+        {
+            return passphrase_cache.ensure_passphrase(session, fpr);
+        }
+
     } // namespace Adapter
 
     void throw_status(::PEP_STATUS status)
diff --git a/src/Adapter.hh b/src/Adapter.hh
index ba07308..312a145 100644
--- a/src/Adapter.hh
+++ b/src/Adapter.hh
@@ -20,26 +20,6 @@ namespace pEp {
             Async
         };
 
-        int _inject_sync_event(::SYNC_EVENT ev, void *management);
-        int _process_sync_event(::SYNC_EVENT ev, void *management);
-
-        ::PEP_STATUS _ensure_passphrase(::PEP_SESSION session, const char *fpr);
-
-        void start_sync();
-
-        template<class T = void>
-        void startup(
-            T *obj = nullptr,
-            std::function<void(T *)> _startup = nullptr,
-            std::function<void(T *)> _shutdown = nullptr);
-
-        // returns 'true' when called from the "sync" thread, 'false' otherwise.
-        bool on_sync_thread();
-
-        // returns the thread id of the sync thread
-        std::thread::id sync_thread_id();
-
-
         // The thread-local pEp-session
         // CAVEAT: there is a default constructor Sesssion(),
         // BUT
@@ -129,6 +109,26 @@ namespace pEp {
 
         extern thread_local Session session;
 
+        // ---------------------------------------------------------------------------------------
+        // SYNC
+        // ---------------------------------------------------------------------------------------
+        int _cb_enqueue_sync_event(::SYNC_EVENT ev, void *management);
+        int _cb_pass_sync_event_to_engine(::SYNC_EVENT ev, void *management);
+
+        void start_sync();
+
+        template<class T = void>
+        void startup(
+            T *obj = nullptr,
+            std::function<void(T *)> _startup = nullptr,
+            std::function<void(T *)> _shutdown = nullptr);
+
+        // returns 'true' when called from the "sync" thread, 'false' otherwise.
+        bool on_sync_thread();
+
+        // returns the thread id of the sync thread
+        std::thread::id sync_thread_id();
+
         // only injects a NULL event into sync_event_queue
         // Use this if adapter_manages_sync_thread
         // Inject first, then join your thread.
@@ -140,6 +140,8 @@ namespace pEp {
 
         bool is_sync_running();
         bool in_shutdown();
+
+        ::PEP_STATUS _ensure_passphrase(::PEP_SESSION session, const char *fpr);
     } // namespace Adapter
 
     // throws std::bad_alloc if status==PEP_OUT_OF_MEMORY,