instrument: spline EGs — hard points on the one shared spline, a drawn contour per envelope beside its staged state, payload v13

src/core/instrument/engine/voice.cpp

@@ -72,6 +72,26 @@ void Voice::start(int note, int velocity, const SampleData& sample, bool declick
     loop_ = instrument::engine::loop::resolveLoop(sample.loop, sample.loopCrossfadeFrames,
                                                   frameCount, playMode_ == PlayMode::Gate);
 
+    // Bind whichever EGs are drawn. Rebound on EVERY note-on rather than cached: a reload hands
+    // the engine a fresh SampleData, so a stale pointer into the previous one is the bug this
+    // avoids. A Staged EG clears its cursor, which is what keeps the per-sample path off the
+    // spline branch entirely.
+    splineScale_ = frameCount > 0 ? 1.0 / static_cast<double>(frameCount) : 0.0;
+    if (p.ampSpline.mode == EnvMode::Spline) ampSplineCur_.bind(p.ampSpline.contour);
+    else ampSplineCur_.clear();
+    if (p.pitchEnv.enabled && p.pitchSpline.mode == EnvMode::Spline) {
+        pitchSplineCur_.bind(p.pitchSpline.contour);
+        pitchSplineDepth_ = p.pitchEnv.peakSemitones;
+    } else {
+        pitchSplineCur_.clear();
+        pitchSplineDepth_ = 0.0;
+    }
+    if (p.filter.enabled && p.filterSpline.mode == EnvMode::Spline) {
+        filterSplineCur_.bind(p.filterSpline.contour);
+    } else {
+        filterSplineCur_.clear();
+    }
+
     // Amplitude envelope: Gate = AHDSR (all five fields read from play.adsr, resolved to
     // frames from stored seconds at load time); Trigger = the staged AHD over the % play span.
     const std::int64_t postStart = frameCount - start;  // >= 1 (start clamped < frameCount)