src/channel.c

@@ -19,7 +19,7 @@ void channel_add(jack_client_t *client, int idx)
     if (!channels[idx].audio_in || !channels[idx].audio_out) {
         fprintf(stderr, "Failed to register ports for channel %d\n", next_channel_id);
         /* Do NOT mark channel active – process loop will skip it */
-        channels[idx].active = 0;
+        atomic_store(&channels[idx].active, 0);
         return;
     }
 
@@ -36,8 +36,7 @@ void channel_add(jack_client_t *client, int idx)
 
 void channel_remove(jack_client_t *client, int idx)
 {
-    jack_port_unregister(client, channels[idx].audio_in);
+    (void)client;
-    jack_port_unregister(client, channels[idx].audio_out);
     atomic_store(&channels[idx].active, 0);
     channel_count--;
 }

src/looper.c

@@ -19,6 +19,9 @@ jack_port_t *midi_control_port = NULL;
 jack_port_t *midi_clock_port = NULL;
 atomic_int  control_key_active = 0;
 
+/* Deferred removal index (1 second grace) */
+static int pending_unregister_idx = -1;
+
 /* ----------------------------------------------------------------
  * process callback
  * ---------------------------------------------------------------- */
@@ -198,6 +201,18 @@ int looper_init(jack_client_t *client)
  * ---------------------------------------------------------------- */
 void looper_process_commands(jack_client_t *client)
 {
+    /* Unregister any ports that were marked for deferred removal.
+       By now the real‑time thread has had at least one full cycle
+       to see the `active = 0` store. */
+    if (pending_unregister_idx != -1) {
+        int idx = pending_unregister_idx;
+        if (channels[idx].audio_in)
+            jack_port_unregister(client, channels[idx].audio_in);
+        if (channels[idx].audio_out)
+            jack_port_unregister(client, channels[idx].audio_out);
+        pending_unregister_idx = -1;
+    }
+
     if (atomic_exchange(&cmd_add, 0)) {
         int idx;
         for (idx = 0; idx < MAX_CHANNELS; idx++)
@@ -212,7 +227,9 @@ void looper_process_commands(jack_client_t *client)
         for (int idx = 1; idx < MAX_CHANNELS; idx++)
             if (channels[idx].active) remove_idx = idx;
         if (remove_idx != -1) {
+            /* Mark inactive now; ports will be unregistered next round */
             channel_remove(client, remove_idx);
+            pending_unregister_idx = remove_idx;
         }
     }
 }