Γ-W1-T2: the master bus — a true-peak limiter whose ceiling is a theorem, the meter's published half, and the plugin's first PDC report

src/shell/instrument/processor_state.cpp

@@ -12,6 +12,7 @@
 #include <vector>
 
 #include "pluginterfaces/base/ibstream.h"
+#include "pluginterfaces/vst/ivsteditcontroller.h"  // RestartFlags::kLatencyChanged
 
 #include "core/instrument/engine/master_gain.h"      // masterGainMaxLinear (post-mixer gain clamp)
 #include "core/instrument/map/component_state_io.h"  // the ComponentState codec
@@ -148,8 +149,46 @@ InstrumentParams ReaSamplerProcessor::instrumentParams() {
 }
 
 void ReaSamplerProcessor::setInstrumentParams(const InstrumentParams& params) {
-    std::lock_guard<std::mutex> lock(paramsMutex_);
-    params_ = params;
+    {
+        std::lock_guard<std::mutex> lock(paramsMutex_);
+        params_ = params;
+    }
+    // Every writer of the parameter set — setState, the editor's commits, the bake's adopt —
+    // funnels through here, so mirroring the limiter flag at this one point is what keeps the
+    // audio thread's copy and the latency report from ever lagging what is persisted.
+    publishLimiterEnabled(params.limiterEnabled);
+}
+
+void ReaSamplerProcessor::publishLimiterEnabled(bool on) {
+    limiterEnabled_.store(on, std::memory_order_relaxed);
+    limiter_.setEnabled(on);
+}
+
+void ReaSamplerProcessor::setLimiterEnabled(bool on) {
+    {
+        std::lock_guard<std::mutex> lock(paramsMutex_);
+        if (params_.limiterEnabled == on) return;  // no change: no restart to request
+        params_.limiterEnabled = on;
+    }
+    publishLimiterEnabled(on);
+    // The SDK requires this on the UI thread and answers getLatencySamples only after the host's
+    // own deactivate/reactivate — so the flag above is already committed by the time the host
+    // asks. This is a kLatencyChanged restart with the bus untouched, NOT the retired per-mode
+    // kIoChanged bus renegotiation (see initialize()); do not conflate the two.
+    if (componentHandler) componentHandler->restartComponent(kLatencyChanged);
+}
+
+MasterBusMeter ReaSamplerProcessor::masterBusMeter() const {
+    MasterBusMeter m;
+    m.peakL = meterPeakL_.load(std::memory_order_relaxed);
+    m.peakR = meterPeakR_.load(std::memory_order_relaxed);
+    m.minGain = meterMinGain_.load(std::memory_order_relaxed);
+    m.clip = meterClip_.load(std::memory_order_relaxed);
+    return m;
+}
+
+void ReaSamplerProcessor::clearMasterBusClip() {
+    meterClip_.store(false, std::memory_order_relaxed);
 }
 
 void ReaSamplerProcessor::publishLiveParams() {