refactor: move shutdown logic out of signal handler into main loop

engine/src/looper.c

@@ -79,15 +79,19 @@ static void looper_cleanup(jack_client_t *client) {
     }
 }
 
-/* Signal handler: deactivate and cleanup before exit */
+void looper_shutdown(jack_client_t *client) {
+    jack_deactivate(client);
+    looper_cleanup(client);
+    jack_client_close(client);
+    log_close();
+}
+
+volatile int looper_quit = 0;
+
+/* Signal handler: set quit flag only */
 static void signal_handler(int sig) {
     (void)sig;
-    if (global_client) {
+    looper_quit = 1;
-        looper_cleanup(global_client);
-        jack_client_close(global_client);
-    }
-    log_close();
-    exit(0);
 }
 
 static void looper_write_status(void) {

engine/src/looper.h

@@ -16,4 +16,10 @@ void jack_shutdown_cb(void *arg);
 /* Main‑loop command processing (add/remove channels) */
 void looper_process_commands(jack_client_t *client);
 
+/* Shutdown (must be called from the main thread after looper_quit is set) */
+void looper_shutdown(jack_client_t *client);
+
+/* Flag set by signal handler – main loop should check this */
+extern volatile int looper_quit;
+
 #endif

engine/src/main.c

@@ -49,7 +49,7 @@ int main(int argc, char *argv[]) {
 
   log_msg("looper running (client name '%s')", client_name);
 
-  while (1) {
+  while (!looper_quit) {
     looper_process_commands(client);
     {
       struct timespec ts = {.tv_sec = 0, .tv_nsec = 10000000};
@@ -57,7 +57,6 @@ int main(int argc, char *argv[]) {
     }
   }
 
-  jack_client_close(client);
+  looper_shutdown(client);
-  log_close();
   return 0;
 }