Fix spline-drag rollback, bake contour leak, held-note live miss, amp clamp

Editor close mid-drag now rolls back published contours like capture-loss does; bake detaches liveContours so a printed capture can't observe a live drag; a held note now receives a live publish that lands in the same block as a note-on; amp spline read clamped to [0,1].

tests/test_live_delivery.cpp

@@ -1167,6 +1167,38 @@ static void testVelocityGainSurvivesAHostilePublishThatReallyLands() {
     CHECK(proportional);
 }
 
+// A note-on that lands in the same block boundary as a publish must not let the already-
+// sounding voice miss it: startVoice used to call refreshLive() bare, which consumes the
+// generation stamp without applying it to the voices already active — a held note that shared
+// a block with a note-on then never saw the publish at all (not merely delayed a block).
+static void testHeldVoiceReceivesALivePublishThatCoincidesWithANoteOn() {
+    SampleData s;
+    s.frames.assign(200000, 1.0f);  // DC: the envelope alone shapes the output
+    s.sampleRate = kRate;
+    s.rootNote = 60;
+    s.play.adsr.attackFrames = 0;
+    s.play.adsr.sustainLevel = 1.0;
+    s.play.adsr.releaseFrames = 480000;  // long enough that release never intrudes
+
+    LiveParams block;
+    s.live = █
+    VoiceEngine engine(2, s);
+    engine.noteOn(60, 100);  // voice A, sustaining at the dialed 1.0
+
+    LiveValues quieter = foldLive(s.play, s.keyTrack);
+    quieter.adsr.sustainLevel = 0.2;
+    block.publish(quieter);
+
+    engine.noteOn(61, 100);  // voice B starts in the SAME generation as the publish
+
+    std::vector<AudioSample> out;
+    for (int i = 0; i < 20; ++i) engine.render(out, 512);  // let voice A's glide settle
+
+    // Both voices settle at 0.2 — a held voice that missed the publish would still sit at 1.0,
+    // for a combined 1.2 rather than 0.4.
+    CHECK(std::fabs(static_cast<double>(out.back()) - 0.4) < 0.01);
+}
+
 int main() {
     testStageDurationChangeHoldsPhase();
     testShortenedStageStillLandsContinuously();
@@ -1189,6 +1221,7 @@ int main() {
     testAPublishedPitchOffsetRefitsThePitchEnvelopeSpan();
     testPitchRatioAndVelocityGainStayLatched();
     testVelocityGainSurvivesAHostilePublishThatReallyLands();
+    testHeldVoiceReceivesALivePublishThatCoincidesWithANoteOn();
     if (g_fail == 0) std::printf("live_delivery tests passed\n");
     return g_fail == 0 ? 0 : 1;
 }