replace screenshot, fix arpeggiator reset

Source/DSP/Arpeggiator.h

@@ -68,6 +68,12 @@ public:
         bool wasIdle = heldNotes.empty();
         heldNotes.push_back(note);
         velocities[note] = velocity;
+        // The held set changed, so the pitch pool changed too. Restart the
+        // sequence from the top so the pattern always starts from a known
+        // note instead of continuing at stepIndex % newPoolSize.
+        stepIndex = 0;
+        randomOncePool.clear();
+        randomOnceOrder.clear();
         // A fresh key press should sound immediately instead of waiting for
         // the next host-synced tick.
         if (wasIdle)
@@ -76,8 +82,12 @@ public:
 
     void noteOff(int note) {
         auto it = std::find(heldNotes.begin(), heldNotes.end(), note);
-        if (it != heldNotes.end())
+        if (it != heldNotes.end()) {
             heldNotes.erase(it);
+            stepIndex = 0;
+            randomOncePool.clear();
+            randomOnceOrder.clear();
+        }
     }
 
     bool hasHeldNotes() const { return !heldNotes.empty(); }
@@ -97,6 +107,8 @@ public:
         heldNotes.clear();
         stepIndex = 0;
         needsImmediateStep = false;
+        randomOncePool.clear();
+        randomOnceOrder.clear();
     }
 
     // Advances one step. Notes that should stop go into `notesToStop`