Bake window: derive it from the rate the voice actually reads at, so a dialled Rate or downward Pitch no longer truncates the file

src/core/instrument/engine/envelopes.h

@@ -421,7 +421,12 @@ public:
     // Peer of AdsrEnvelope::snapLive (see it for why the two paths cannot share code): a voice
     // that has rendered nothing takes the new shape and depth outright. `enabled` is a discrete
     // toggle travelling by reload, so the caller's copy of it is deliberately ignored.
-    void snapLive(const PitchEnvParams& params) {
+    //
+    // Both live entry points re-take `spanFrames` rather than keeping configure()'s: the span is
+    // an OUTPUT-frame duration the caller converts from the read rate, and that rate carries a
+    // live control (voice.h's pitchEnvSpanFrames). Passing the span back unchanged is exact.
+    void snapLive(std::int64_t spanFrames, const PitchEnvParams& params) {
+        span_ = spanFrames > 0 ? spanFrames : 0;
         params_.peakSemitones = params.peakSemitones;
         params_.shape = params.shape;
         fit_ = fitAhd(span_, params_.shape);
@@ -430,9 +435,11 @@ public:
 
     // Live parameter delivery, same rule as AdsrEnvelope::applyLive: hold the normalized
     // position within whichever leg the envelope is in, and absorb the depth step (peak is a
-    // level, not a duration).
-    void applyLive(const PitchEnvParams& params) {
+    // level, not a duration). A moved span re-fits under the same rule, so a live Pitch move
+    // reshapes this envelope continuously instead of leaving it on the note-on read rate.
+    void applyLive(std::int64_t spanFrames, const PitchEnvParams& params) {
         const double before = offsetAt();
+        span_ = spanFrames > 0 ? spanFrames : 0;
         const AhdSpan next = fitAhd(span_, params.shape);
         pos_ = holdPhase(fit_, next);
         params_.peakSemitones = params.peakSemitones;