instrument: deliver continuous playback params live to sounding voices via a seqlock block, holding normalized stage position across time edits

src/shell/instrument/reasampler_processor.h

@@ -19,6 +19,7 @@
 #include "shell/instrument/reaper_bridge.h"
 #include "core/instrument/map/sample_map.h"     // InstrumentParams (the one parameter set)
 #include "core/instrument/map/component_state_io.h"  // ComponentState codec
+#include "core/instrument/engine/live_params.h"  // LiveParams (the live-parameter block)
 #include "core/instrument/engine/voice_engine.h"
 
 namespace reasampler::vst {
@@ -151,6 +152,15 @@ public:
     InstrumentParams instrumentParams();
     void setInstrumentParams(const InstrumentParams& params);
 
+    // Republishes the live-parameter block from the stored parameter set, resolved against the
+    // rate the loaded capture was built at so an unmoved value folds to exactly the frames the
+    // voices already latched. THE tier-3 commit: no bridge read, no WAV re-decode, no engine
+    // rebuild, no snapshot swap — the sounding note follows the knob. Persistence is
+    // unaffected: getState still serializes params_, so callers pair this with
+    // setInstrumentParams exactly as they paired it with reloadInstrument. No-op before
+    // anything has been decoded (the next reload bakes and publishes). UI thread.
+    void publishLiveParams();
+
     // Per-instance channel mode (mono | stereo), guarded by channelModeMutex_, never read
     // on the audio thread. Decode policy only (downmix vs L/R split) — the output bus is
     // fixed stereo, so a mode change never renegotiates host I/O.
@@ -225,6 +235,16 @@ private:
 
     ReaperBridge bridge_;
 
+    // The ONE live-parameter block for this instance, declared ahead of the instrument slots
+    // so it outlives every snapshot that points at it (members destruct in reverse order).
+    // Both live_ and draining_ observe this same block — a block owned by a snapshot would
+    // leave the drain's still-sounding voices deaf to the knob under them.
+    instrument::engine::LiveParams liveParams_;
+    // The rate the loaded capture was decoded/built at, so a live republish resolves the
+    // stored wall-clock seconds to exactly the frames the built SampleData carries. 0 = nothing
+    // built yet.
+    std::atomic<int> builtSampleRate_{0};
+
     // --- The audio-thread handoff (drain slot) ---
     // process() atomically loads live_ + draining_ at block start (two acquires, no lock).
     // reloadInstrument() (off-thread, serialized by reloadMutex_) swaps a new build into