Phase S FB1 (r11): Sample-view recomposition — knob deck + elastic full-width hero + curve popup w/ right-click delete + post-mixer master gain (ComponentState v8)

src/vst/reasampler_processor.h

@@ -210,6 +210,17 @@ public:
     MonoTrigger monoTrigger();
     void setMonoTrigger(MonoTrigger trigger);
 
+    // --- FB1 post-mixer master gain (per-instance, persisted in component state v8) ---------
+    // LINEAR gain in [0, masterGainMaxLinear()] (0.0 = -inf/true silence, 1.0 = unity, cap =
+    // +24 dB; the pure master_gain module owns the dB knob taper). Held in an atomic so the
+    // audio thread applies it with ONE relaxed load per block as a post-sum multiply over the
+    // rendered output (engine + drain + preview) — no lock, no rebuild, no per-voice cost.
+    // Written by the editor's Gain knob (UI thread) and setState; read by getState + process().
+    double masterGainLinear() const {
+        return static_cast<double>(masterGain_.load(std::memory_order_relaxed));
+    }
+    void setMasterGainLinear(double linear);  // clamped to [0, masterGainMaxLinear()]
+
     // Fire a one-shot PREVIEW note-on / note-off through the live instrument's PREVIEW CARD
     // (S-VIEW-4; Phase S isolation) — a dedicated single voice structurally OUTSIDE the MIDI
     // pool, so a full pool never drops a preview and a preview never steals a playing voice.
@@ -355,6 +366,11 @@ private:
     VoiceMode voiceMode_ = VoiceMode::Poly;
     MonoTrigger monoTrigger_ = MonoTrigger::Retrigger;
 
+    // FB1 post-mixer master gain (LINEAR; persisted in component state v8). A lock-free
+    // atomic — the ONE voice-param the audio thread reads directly (a single relaxed load
+    // per block, applied as a post-sum multiply). Default unity = pre-FB1 output.
+    std::atomic<float> masterGain_{1.0f};
+
     // --- S-VIEW-4 preview-trigger mailbox (off-thread -> audio thread, lock-free) ---------
     // The editor's preview-trigger button posts a note-on/off request from the UI thread; process()
     // drains it at block start and drives the live instrument's PREVIEW CARD (Phase S — never the