diff --git a/app/build.gradle.kts b/app/build.gradle.kts
index 766d19c..4ed85b7 100644
--- a/app/build.gradle.kts
+++ b/app/build.gradle.kts
@@ -22,8 +22,8 @@ android {
         // (android.media.midi) and AAudio low-latency audio we rely on.
         minSdk = 26
         targetSdk = 34
-        versionCode = 47
-        versionName = "0.21.0"
+        versionCode = 48
+        versionName = "0.21.1"
 
         // We provide our own instrumentation runner if/when tests are added.
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
diff --git a/app/src/main/java/space/rcmd/android/sizzle/MainActivity.kt b/app/src/main/java/space/rcmd/android/sizzle/MainActivity.kt
index c93831d..e00ea40 100644
--- a/app/src/main/java/space/rcmd/android/sizzle/MainActivity.kt
+++ b/app/src/main/java/space/rcmd/android/sizzle/MainActivity.kt
@@ -75,10 +75,13 @@ class MainActivity : ComponentActivity() {
                 SizzleAppUi(viewModel)
             }
         }
-    }
 
-    override fun onStart() {
-        super.onStart()
+        // Start MIDI listening (USB + BLE) and the MIDI clock here — bound to the
+        // Activity's WHOLE lifetime (onCreate..onDestroy), not onStart/onStop — so a
+        // connected controller keeps driving the app while the screen is off. The
+        // audio engine already runs a continuous output stream via the started
+        // PlaybackService, which keeps the process alive to receive those events in
+        // the background; closing the ports on onStop was the only reason input died.
         midi.start()
         app.midiClock.start()
     }
@@ -93,11 +96,19 @@ class MainActivity : ComponentActivity() {
 
     override fun onStop() {
         // Autosave the project whenever we leave the foreground, so a later
-        // system-kill (or crash) resumes from here on next launch.
+        // system-kill (or crash) resumes from here on next launch. MIDI is
+        // deliberately NOT stopped here (see onCreate / onDestroy) so controllers
+        // keep working with the screen off or the app backgrounded.
         app.projectStore.save(app.project)
+        super.onStop()
+    }
+
+    override fun onDestroy() {
+        // Release MIDI only when the Activity is actually torn down (task removed or
+        // finishing), not merely backgrounded / screen-off.
         midi.stop()
         app.midiClock.stop()
-        super.onStop()
+        super.onDestroy()
     }
 
     // ---- Hardware input forwarding ----