fix(voice): Trigger legato keys on held-stack depth, CC123 allNotesOff clears mono stack, voice-param edits rebuild from decoded PCM (no re-decode), mono sizes 1 shifter ring

src/vst/reasampler_processor.h

@@ -200,8 +200,9 @@ public:
     // --- Phase S voice-system parameters (per-instance, persisted in component state v7) ---
     // Read/written on the UI thread (the editor's voice deck) and by getState/setState; guarded
     // by voiceParamsMutex_. NOT read on the audio thread — each setter rebuilds the VoiceEngine
-    // OFF-thread through reloadFromBank's drain-slot swap, so changing polyphony / mode / the
-    // retrigger toggle never cuts a ringing tail (the same path FA1 added for curve edits).
+    // OFF-thread via rebuildVoiceEngine (a LIGHT rebuild around the already-decoded keymap; no
+    // bridge read, no WAV re-decode) published through the same tail-preserving drain-slot swap,
+    // so changing polyphony / mode / the retrigger toggle never cuts a ringing tail.
     int voiceCount();
     void setVoiceCount(int count);        // clamped to kMinVoiceCount..kMaxVoiceCount
     VoiceMode voiceMode();
@@ -240,6 +241,24 @@ private:
     // proof (see below) covers the free.
     void retireIdleDrain();
 
+    // Phase S voice-param LIGHT rebuild (voice-review Major #3): rebuild the engine + preview
+    // card around a COPY of the LIVE instrument's already-decoded Keymap — no bridge read, no
+    // filesystem, no WAV re-decode — and publish through the same tail-preserving drain-slot
+    // swap as a full reload. A polyphony/mode/trigger change touches no audio data, so the
+    // full reloadFromBank (which re-decodes every zone WAV from disk on the UI thread) was
+    // pure waste — a visible UI stall on a many-zone instrument. Copying the keymap is safe:
+    // it is immutable after construction and, under reloadMutex_, the live instrument can
+    // neither be swapped nor freed while we read it. When nothing is loaded this is a no-op —
+    // the new params bake into the next real reload. Off the audio thread only.
+    void rebuildVoiceEngine();
+
+    // Publish `built` (null = install silence) into live_: prune the graveyard by the last
+    // process()-published generation, swap `built` into live_, displace the previous live into
+    // the drain slot, and park the drain-evicted instrument in the graveyard. REQUIRES
+    // reloadMutex_ held — factored out so reloadFromBank and rebuildVoiceEngine share the ONE
+    // safety-critical swap dance (see the handoff proof below).
+    void publishBuiltLocked(std::unique_ptr<LoadedInstrument> built);
+
     ReaperBridge bridge_;
 
     // --- The audio-thread handoff (S4 real-time discipline, FA1 drain slot) --