Initial release — InstaGrain granular synthesizer v1.0

8-voice polyphonic granular synth (VST3/AU/LV2) with:
- 128 grain pool per voice, Hann windowing, linear interpolation
- Root note selector, sample rate correction, sustain pedal (CC64)
- Scatter controls, direction modes (Fwd/Rev/PingPong), freeze
- ADSR envelope, global filter (LP/HP/BP), reverb
- Waveform display with grain visualization
- Drag & drop sample loading, full state save/restore
- CI/CD for Windows/macOS/Linux

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Source/GrainCloud.h

@@ -0,0 +1,52 @@
+#pragma once
+#include <JuceHeader.h>
+#include "Grain.h"
+
+class GrainCloud
+{
+public:
+    static constexpr int maxGrains = 128;
+
+    enum class Direction { Forward, Reverse, PingPong };
+
+    GrainCloud();
+
+    void prepare (double sampleRate);
+    void processBlock (juce::AudioBuffer<float>& output, int numSamples,
+                       const juce::AudioBuffer<float>& sourceBuffer);
+    void reset();
+
+    // Parameters (atomic — GUI writes, audio reads)
+    std::atomic<float> position     { 0.5f };     // 0-1
+    std::atomic<float> grainSizeMs  { 100.0f };   // 10-500
+    std::atomic<float> density      { 10.0f };     // 1-100 grains/sec
+    std::atomic<float> pitchSemitones { 0.0f };   // -24..+24
+    std::atomic<float> pan          { 0.0f };      // -1..+1
+    std::atomic<float> posScatter   { 0.0f };     // 0-1
+    std::atomic<float> sizeScatter  { 0.0f };     // 0-1
+    std::atomic<float> pitchScatter { 0.0f };     // 0-1
+    std::atomic<float> panScatter   { 0.0f };     // 0-1
+    std::atomic<int>   direction    { 0 };         // 0=Fwd, 1=Rev, 2=PingPong
+    std::atomic<bool>  freeze       { false };
+
+    // Extra pitch offset from MIDI note
+    float midiPitchOffset = 0.0f;
+
+    // Sample rate correction: sourceSampleRate / dawSampleRate
+    float sampleRateRatio = 1.0f;
+
+    // For visualization — snapshot of active grains
+    struct GrainInfo { int startSample; int lengthSamples; float progress; };
+    std::array<GrainInfo, maxGrains> getActiveGrainInfo() const;
+    int getActiveGrainCount() const;
+
+private:
+    double currentSampleRate = 44100.0;
+    std::array<Grain, maxGrains> grains;
+    GrainWindow window;
+    int samplesUntilNextGrain = 0;
+    juce::Random rng;
+
+    void spawnGrain (const juce::AudioBuffer<float>& sourceBuffer);
+    float readSampleInterpolated (const juce::AudioBuffer<float>& buffer, double position) const;
+};