Bump version to 0.2.0

- Remove Music button, OnMusic/RunMusicAsync/StopMusic and all music fields
- MusicAnalyzer: remove Analyze, DecodeToMono, MusicPattern record;
  keep ExtractFeatures/MapPitchToPeriod/BuildWaveFrame/TickFeature (used by LiveCapture)
- Remove unused NAudio.Wave and System.Diagnostics imports from MainForm
- Fix LiveCapture overlap: sliding window with 50% overlap (was dropping every other frame)
- Buttons resized to 80px (Test/Live/Pattern/Stop All)

LiveCapture.cs

@@ -0,0 +1,165 @@
+using System.Numerics;
+using FftSharp;
+using NAudio.CoreAudioApi;
+using NAudio.Wave;
+
+namespace Substation;
+
+public class LiveCapture : IDisposable
+{
+    readonly State _state;
+    readonly MMDevice _device;
+    WasapiLoopbackCapture? _capture;
+    Thread? _processThread;
+    volatile bool _running;
+
+    readonly Queue<double> _sampleBuffer = new();
+    readonly object _bufferLock = new();
+
+    double[]? _prevRhythmMag;
+    double _liveMaxFlux;
+    double _liveMaxMelodyEnergy;
+    int _sampleRate;
+    int _fftsPerTick;
+    int _fftIndexInTick;
+
+    public event Action? Stopped;
+
+    public LiveCapture(State state, MMDevice device)
+    {
+        _state = state;
+        _device = device;
+    }
+
+    public void Start()
+    {
+        _running = true;
+        _capture = new WasapiLoopbackCapture(_device);
+        _sampleRate = _capture.WaveFormat.SampleRate;
+        _fftsPerTick = Math.Max(1, (int)Math.Round(MusicAnalyzer.TickDuration * _sampleRate / MusicAnalyzer.HopSize));
+
+        _capture.DataAvailable += OnDataAvailable;
+        _capture.RecordingStopped += OnRecordingStopped;
+
+        _processThread = new Thread(ProcessLoop) { IsBackground = true, Name = "LiveCapture-FFT" };
+        _processThread.Start();
+
+        _capture.StartRecording();
+        Console.WriteLine($"[live] capture started: {_device.FriendlyName} ({_sampleRate}Hz, {_capture.WaveFormat.Channels}ch)");
+    }
+
+    public void Stop()
+    {
+        _running = false;
+        try { _capture?.StopRecording(); } catch { }
+    }
+
+    void OnDataAvailable(object? sender, WaveInEventArgs e)
+    {
+        int channels = _capture!.WaveFormat.Channels;
+        int bytesPerSample = _capture.WaveFormat.BitsPerSample / 8;
+        int frameSize = channels * bytesPerSample;
+        int sampleCount = e.BytesRecorded / frameSize;
+
+        lock (_bufferLock)
+        {
+            for (int i = 0; i < sampleCount; i++)
+            {
+                int offset = i * frameSize;
+                float left = BitConverter.ToSingle(e.Buffer, offset);
+                float right = channels >= 2
+                    ? BitConverter.ToSingle(e.Buffer, offset + bytesPerSample)
+                    : left;
+                _sampleBuffer.Enqueue((left + right) * 0.5);
+            }
+
+            // Cap buffer size to prevent memory growth if processing falls behind
+            while (_sampleBuffer.Count > _sampleRate * 2)
+                _sampleBuffer.Dequeue();
+        }
+    }
+
+    void OnRecordingStopped(object? sender, StoppedEventArgs e)
+    {
+        _running = false;
+        Stopped?.Invoke();
+        Console.WriteLine("[live] capture stopped");
+    }
+
+    void ProcessLoop()
+    {
+        var window = new FftSharp.Windows.Hanning();
+        var buffer = new double[MusicAnalyzer.WindowSize];
+        var tf = new MusicAnalyzer.TickFeature();
+        double[]? overlap = null; // last HopSize samples from previous window
+
+        while (_running)
+        {
+            double[]? windowData = null;
+
+            lock (_bufferLock)
+            {
+                int needed = overlap != null ? MusicAnalyzer.HopSize : MusicAnalyzer.WindowSize;
+                if (_sampleBuffer.Count >= needed)
+                {
+                    if (overlap != null)
+                    {
+                        Array.Copy(overlap, 0, buffer, 0, MusicAnalyzer.HopSize);
+                        for (int i = 0; i < MusicAnalyzer.HopSize; i++)
+                            buffer[MusicAnalyzer.HopSize + i] = _sampleBuffer.Dequeue();
+                    }
+                    else
+                    {
+                        for (int i = 0; i < MusicAnalyzer.WindowSize; i++)
+                            buffer[i] = _sampleBuffer.Dequeue();
+                    }
+                    // Save last HopSize samples for next window's overlap
+                    overlap = new double[MusicAnalyzer.HopSize];
+                    Array.Copy(buffer, MusicAnalyzer.HopSize, overlap, 0, MusicAnalyzer.HopSize);
+                    windowData = buffer;
+                }
+            }
+
+            if (windowData == null)
+            {
+                Thread.Sleep(5);
+                continue;
+            }
+
+            window.ApplyInPlace(windowData);
+            var spectrum = FFT.Forward(windowData);
+            var mag = FFT.Magnitude(spectrum);
+
+            var (rhythmEnergy, rhythmFlux, melodyEnergy, melodyFreq) =
+                MusicAnalyzer.ExtractFeatures(mag, _prevRhythmMag, _sampleRate);
+
+            _prevRhythmMag = mag;
+
+            // Adaptive normalization: running max with slow decay
+            _liveMaxFlux = Math.Max(rhythmFlux, _liveMaxFlux * 0.999);
+            _liveMaxMelodyEnergy = Math.Max(melodyEnergy, _liveMaxMelodyEnergy * 0.999);
+
+            tf.RhythmFlux = Math.Max(tf.RhythmFlux, rhythmFlux);
+            tf.MelodyEnergy += melodyEnergy;
+            tf.MelodyFreqSamples.Add(melodyFreq);
+            tf.MelodyCount++;
+            _fftIndexInTick++;
+
+            if (_fftIndexInTick >= _fftsPerTick)
+            {
+                var (frameA, frameB) = MusicAnalyzer.BuildWaveFrame(tf, _liveMaxFlux, _liveMaxMelodyEnergy);
+                _state.EnqueueStream('A', new[] { frameA });
+                _state.EnqueueStream('B', new[] { frameB });
+
+                tf = new MusicAnalyzer.TickFeature();
+                _fftIndexInTick = 0;
+            }
+        }
+    }
+
+    public void Dispose()
+    {
+        _running = false;
+        try { _capture?.Dispose(); } catch { }
+    }
+}

MainForm.cs

@@ -1,7 +1,6 @@
 using System.ComponentModel;
 using System.Drawing.Drawing2D;
-using System.Diagnostics;
-using NAudio.Wave;
+using NAudio.CoreAudioApi;
 
 namespace Substation;
 
@@ -36,19 +35,25 @@ public class MainForm : Form
     readonly TrackBar _limitBarB;
     readonly Label _lblLimitA;
     readonly Label _lblLimitB;
+    readonly Label _lblLimitValA;
+    readonly Label _lblLimitValB;
     readonly CheckBox _chkScaleA;
     readonly CheckBox _chkScaleB;
+    readonly CheckBox _chkSwap;
 
     readonly Icon _iconNeutral;
     readonly Icon _iconActive;
     readonly Icon _iconHot;
     string _trayState = "";
 
-    readonly Button _btnMusic;
+    readonly Button _btnLive;
+    readonly Button _btnPattern;
     readonly Label _lblTrack;
-    bool _isMusicRunning;
-    WaveOutEvent? _audioOut;
-    Stopwatch? _musicStopwatch;
+    readonly Label _lblAudioDev;
+    readonly ComboBox _cboAudioDev;
+    bool _isLiveRunning;
+    bool _isPatternRunning;
+    LiveCapture? _liveCapture;
 
     public MainForm(CoyoteDevice device, State state, Server server)
     {
@@ -58,7 +63,7 @@ public class MainForm : Form
         _loopCts = new CancellationTokenSource();
 
         Text = $"Substation {typeof(MainForm).Assembly.GetName().Version}";
-        ClientSize = new Size(420, 410);
+        ClientSize = new Size(420, 450);
         FormBorderStyle = FormBorderStyle.FixedSingle;
         MaximizeBox = false;
         StartPosition = FormStartPosition.CenterScreen;
@@ -96,39 +101,70 @@ public class MainForm : Form
         _btnConnect = new Button
         {
             Text = "Connect",
-            Location = new Point(296, 64),
-            Size = new Size(108, 24)
+            Location = new Point(236, 64),
+            Size = new Size(80, 24)
         };
         _btnConnect.Click += OnConnect;
 
+        _chkSwap = new CheckBox
+        {
+            Text = "Swap",
+            Location = new Point(328, 66),
+            Size = new Size(56, 20),
+            Checked = false
+        };
+        _chkSwap.CheckedChanged += OnSwapChanged;
+
         _btnTest = new Button
         {
             Text = "Test",
             Location = new Point(16, 96),
-            Size = new Size(100, 32)
+            Size = new Size(80, 32)
         };
         _btnTest.Click += OnTest;
 
-        _btnMusic = new Button
+        _btnLive = new Button
         {
-            Text = "Music",
-            Location = new Point(130, 96),
-            Size = new Size(100, 32)
+            Text = "Live",
+            Location = new Point(104, 96),
+            Size = new Size(80, 32)
         };
-        _btnMusic.Click += OnMusic;
+        _btnLive.Click += OnLive;
+
+        _btnPattern = new Button
+        {
+            Text = "Pattern",
+            Location = new Point(192, 96),
+            Size = new Size(80, 32)
+        };
+        _btnPattern.Click += OnPattern;
 
         _btnStop = new Button
         {
             Text = "Stop All",
-            Location = new Point(244, 96),
-            Size = new Size(100, 32)
+            Location = new Point(280, 96),
+            Size = new Size(80, 32)
         };
         _btnStop.Click += OnStop;
 
+        _lblAudioDev = new Label
+        {
+            Text = "Audio:",
+            Location = new Point(16, 134),
+            Size = new Size(40, 20)
+        };
+        _cboAudioDev = new ComboBox
+        {
+            DropDownStyle = ComboBoxStyle.DropDownList,
+            Location = new Point(60, 132),
+            Size = new Size(344, 22)
+        };
+        PopulateAudioDevices();
+
         _lblTrack = new Label
         {
             Text = "",
-            Location = new Point(16, 134),
+            Location = new Point(16, 158),
             Size = new Size(388, 16),
             ForeColor = Color.DimGray
         };
@@ -136,37 +172,37 @@ public class MainForm : Form
         _lblSendA = new Label
         {
             Text = "Send A",
-            Location = new Point(16, 160),
+            Location = new Point(16, 184),
             Size = new Size(48, 20),
             Font = new Font(Font.FontFamily, 9, FontStyle.Bold)
         };
         _heatA = new HeatMap(60)
         {
-            Location = new Point(72, 158),
+            Location = new Point(72, 182),
             Size = new Size(332, 22)
         };
         _lblSendB = new Label
         {
             Text = "Send B",
-            Location = new Point(16, 188),
+            Location = new Point(16, 212),
             Size = new Size(48, 20),
             Font = new Font(Font.FontFamily, 9, FontStyle.Bold)
         };
         _heatB = new HeatMap(60)
         {
-            Location = new Point(72, 186),
+            Location = new Point(72, 210),
             Size = new Size(332, 22)
         };
         _lblRecvA = new Label
         {
             Text = "Recv A",
-            Location = new Point(16, 216),
+            Location = new Point(16, 240),
             Size = new Size(48, 20),
             Font = new Font(Font.FontFamily, 9, FontStyle.Bold)
         };
         _gaugeRecvA = new ProgressBar
         {
-            Location = new Point(72, 216),
+            Location = new Point(72, 240),
             Size = new Size(332, 20),
             Minimum = 0,
             Maximum = 200,
@@ -175,13 +211,13 @@ public class MainForm : Form
         _lblRecvB = new Label
         {
             Text = "Recv B",
-            Location = new Point(16, 242),
+            Location = new Point(16, 266),
             Size = new Size(48, 20),
             Font = new Font(Font.FontFamily, 9, FontStyle.Bold)
         };
         _gaugeRecvB = new ProgressBar
         {
-            Location = new Point(72, 242),
+            Location = new Point(72, 266),
             Size = new Size(332, 20),
             Minimum = 0,
             Maximum = 200,
@@ -190,25 +226,33 @@ public class MainForm : Form
 
         _lblLimitA = new Label
         {
-            Text = "Lim A: 30",
-            Location = new Point(16, 274),
-            Size = new Size(56, 20),
+            Text = "Lim A",
+            Location = new Point(16, 298),
+            Size = new Size(40, 20),
             Font = new Font(Font.FontFamily, 9, FontStyle.Bold)
         };
         _limitBarA = new TrackBar
         {
-            Location = new Point(72, 270),
-            Size = new Size(250, 45),
+            Location = new Point(60, 294),
+            Size = new Size(220, 45),
             Minimum = 0,
             Maximum = 200,
             TickFrequency = 50,
             Value = 30
         };
         _limitBarA.ValueChanged += OnLimitChanged;
+        FixTrackbarKeys(_limitBarA);
+        _lblLimitValA = new Label
+        {
+            Text = "30",
+            Location = new Point(286, 298),
+            Size = new Size(32, 20),
+            TextAlign = ContentAlignment.MiddleRight
+        };
         _chkScaleA = new CheckBox
         {
             Text = "Scale",
-            Location = new Point(328, 274),
+            Location = new Point(320, 298),
             Size = new Size(76, 24),
             Checked = false
         };
@@ -216,32 +260,40 @@ public class MainForm : Form
 
         _lblLimitB = new Label
         {
-            Text = "Lim B: 30",
-            Location = new Point(16, 312),
-            Size = new Size(56, 20),
+            Text = "Lim B",
+            Location = new Point(16, 346),
+            Size = new Size(40, 20),
             Font = new Font(Font.FontFamily, 9, FontStyle.Bold)
         };
         _limitBarB = new TrackBar
         {
-            Location = new Point(72, 308),
-            Size = new Size(250, 45),
+            Location = new Point(60, 342),
+            Size = new Size(220, 45),
             Minimum = 0,
             Maximum = 200,
             TickFrequency = 50,
             Value = 30
         };
         _limitBarB.ValueChanged += OnLimitChanged;
+        FixTrackbarKeys(_limitBarB);
+        _lblLimitValB = new Label
+        {
+            Text = "30",
+            Location = new Point(286, 346),
+            Size = new Size(32, 20),
+            TextAlign = ContentAlignment.MiddleRight
+        };
         _chkScaleB = new CheckBox
         {
             Text = "Scale",
-            Location = new Point(328, 312),
+            Location = new Point(320, 346),
             Size = new Size(76, 24),
             Checked = false
         };
         _chkScaleB.CheckedChanged += OnLimitChanged;
         OnLimitChanged(null, EventArgs.Empty);
 
-        Controls.AddRange(new Control[] { _lblBle, _lblWs, _lblDeviceName, _txtDeviceName, _btnConnect, _btnTest, _btnMusic, _btnStop, _lblTrack, _lblSendA, _heatA, _lblSendB, _heatB, _lblRecvA, _gaugeRecvA, _lblRecvB, _gaugeRecvB, _lblLimitA, _limitBarA, _chkScaleA, _lblLimitB, _limitBarB, _chkScaleB });
+        Controls.AddRange(new Control[] { _lblBle, _lblWs, _lblDeviceName, _txtDeviceName, _btnConnect, _chkSwap, _btnTest, _btnLive, _btnPattern, _btnStop, _lblAudioDev, _cboAudioDev, _lblTrack, _lblSendA, _heatA, _lblSendB, _heatB, _lblRecvA, _gaugeRecvA, _lblRecvB, _gaugeRecvB, _lblLimitA, _limitBarA, _lblLimitValA, _chkScaleA, _lblLimitB, _limitBarB, _lblLimitValB, _chkScaleB });
 
         // Tray icon — three cached variants: neutral=gray, active=gold, hot=red-orange
         _iconNeutral = CreateVoltageIcon(Color.Gray);
@@ -260,7 +312,7 @@ public class MainForm : Form
         _tray.ContextMenuStrip.Items.Add("Exit", null, (_, _) => ExitFromTray());
         _tray.DoubleClick += (_, _) => ShowFromTray();
 
-        _statusTimer = new System.Windows.Forms.Timer { Interval = 250 };
+        _statusTimer = new System.Windows.Forms.Timer { Interval = 1000 };
         _statusTimer.Tick += OnStatusTick;
         _statusTimer.Start();
 
@@ -269,6 +321,8 @@ public class MainForm : Form
         Resize += OnResize;
 
         _server.ClientChanged += OnWsClientChanged;
+        _device.ConnectionChanged += OnDeviceConnectionChanged;
+        _device.StrengthChanged += OnDeviceStrengthChanged;
     }
 
     async void OnLoad(object? sender, EventArgs e)
@@ -297,6 +351,14 @@ public class MainForm : Form
                     var frame = B0.Build(0, modeA, modeB, valA, valB, freqA, intA, freqB, intB);
                     await _device.SendB0(frame);
                 }
+                if (!IsDisposed)
+                {
+                    BeginInvoke(() =>
+                    {
+                        _heatA.AddTick(freqA, intA, _state.LastActiveA);
+                        _heatB.AddTick(freqB, intB, _state.LastActiveB);
+                    });
+                }
             }
             catch (Exception ex)
             {
@@ -368,36 +430,55 @@ public class MainForm : Form
         BeginInvoke(() =>
         {
             _lblWs.Text = connected ? "WS: client connected" : "WS: idle";
-            _btnTest.Enabled = !connected && !IsTestRunning;
-            _btnMusic.Enabled = !connected && !_isMusicRunning;
+            RefreshButtonStates();
             UpdateTrayIcon();
         });
     }
 
+    void OnDeviceConnectionChanged(bool connected)
+    {
+        if (IsDisposed) return;
+        BeginInvoke(() =>
+        {
+            _lblBle.Text = connected
+                ? $"BLE: connected ({_device.DeviceName})"
+                : "BLE: disconnected";
+            _btnConnect.Enabled = !connected;
+            RefreshButtonStates();
+        });
+    }
+
+    void OnDeviceStrengthChanged(int a, int b)
+    {
+        if (IsDisposed) return;
+        BeginInvoke(() =>
+        {
+            if (_state.SwapChannels) (a, b) = (b, a);
+            _gaugeRecvA.Value = Math.Clamp(a, 0, 200);
+            _gaugeRecvB.Value = Math.Clamp(b, 0, 200);
+        });
+    }
+
+    void RefreshButtonStates()
+    {
+        bool busy = IsTestRunning || _isLiveRunning || _isPatternRunning;
+        _btnTest.Enabled = !_server.HasClient && !busy;
+        _btnLive.Enabled = !_server.HasClient && !busy;
+        _btnPattern.Enabled = !_server.HasClient && !busy;
+        _btnStop.Enabled = true;
+    }
+
     void OnStatusTick(object? sender, EventArgs e)
     {
         if (IsDisposed) return;
-        _lblBle.Text = _device.IsConnected
-            ? $"BLE: connected ({_device.DeviceName})"
-            : "BLE: disconnected";
-        _heatA.AddTick(
-            _state.LastFreqA ?? Array.Empty<byte>(),
-            _state.LastIntA ?? Array.Empty<byte>(),
-            _state.LastActiveA);
-        _heatB.AddTick(
-            _state.LastFreqB ?? Array.Empty<byte>(),
-            _state.LastIntB ?? Array.Empty<byte>(),
-            _state.LastActiveB);
-        _gaugeRecvA.Value = Math.Clamp(_device.StrengthA, 0, 200);
-        _gaugeRecvB.Value = Math.Clamp(_device.StrengthB, 0, 200);
-        _btnTest.Enabled = !_server.HasClient && !IsTestRunning;
-        _btnMusic.Enabled = !_server.HasClient && !_isMusicRunning;
-        _btnStop.Enabled = true;
 
-        if (_isMusicRunning && _musicStopwatch != null)
+        if (_isLiveRunning)
         {
-            var elapsed = _musicStopwatch.Elapsed;
-            _lblTrack.Text = $"Playing  {elapsed:mm\\:ss} / {_musicTotalTime:mm\\:ss}  {Path.GetFileName(_musicFilePath)}";
+            _lblTrack.Text = "Live capture";
+        }
+        else if (_isPatternRunning)
+        {
+            _lblTrack.Text = $"Pattern: {_patternName}";
         }
 
         UpdateTrayIcon();
@@ -457,13 +538,14 @@ public class MainForm : Form
         BeginInvoke(() =>
         {
             IsTestRunning = false;
-            _btnTest.Enabled = !_server.HasClient;
+            RefreshButtonStates();
         });
     }
 
     void OnStop(object? sender, EventArgs e)
     {
-        StopMusic();
+        StopLive();
+        StopPattern();
         _state.SetStrength('A', 0);
         _state.SetStrength('B', 0);
         _state.Stop('A');
@@ -478,111 +560,170 @@ public class MainForm : Form
         var modeB = _chkScaleB.Checked ? LimitMode.Scale : LimitMode.Clamp;
         _state.SetLimitA(maxA, modeA);
         _state.SetLimitB(maxB, modeB);
-        _lblLimitA.Text = $"Lim A: {maxA}";
-        _lblLimitB.Text = $"Lim B: {maxB}";
+        _lblLimitValA.Text = $"{maxA}";
+        _lblLimitValB.Text = $"{maxB}";
     }
 
-    string _musicFilePath = "";
-    TimeSpan _musicTotalTime;
-
-    void OnMusic(object? sender, EventArgs e)
+    void OnSwapChanged(object? sender, EventArgs e)
     {
-        if (_isMusicRunning || _server.HasClient) return;
+        _state.SwapChannels = _chkSwap.Checked;
+    }
 
-        using var dlg = new OpenFileDialog
+    void PopulateAudioDevices()
+    {
+        using var enumerator = new MMDeviceEnumerator();
+        var defaultDev = enumerator.GetDefaultAudioEndpoint(DataFlow.Render, Role.Console);
+        var devices = enumerator.EnumerateAudioEndPoints(DataFlow.Render, DeviceState.Active);
+
+        _cboAudioDev.Items.Clear();
+        int defaultIdx = 0;
+        for (int i = 0; i < devices.Count; i++)
         {
-            Filter = "MP3 files (*.mp3)|*.mp3|All files (*.*)|*.*",
-            Title = "Select music to drive e-stim"
-        };
-        if (dlg.ShowDialog() != DialogResult.OK) return;
-
-        _musicFilePath = dlg.FileName;
-        _musicTotalTime = TimeSpan.Zero;
-        _isMusicRunning = true;
-        _btnMusic.Enabled = false;
-        _btnTest.Enabled = false;
-        _lblTrack.Text = $"Analyzing... {Path.GetFileName(_musicFilePath)}";
-
-        var filePath = _musicFilePath;
-        Task.Run(() => RunMusicAsync(filePath));
+            _cboAudioDev.Items.Add(devices[i]);
+            if (devices[i].ID == defaultDev.ID)
+                defaultIdx = i;
+        }
+        _cboAudioDev.SelectedIndex = defaultIdx;
     }
 
-    async Task RunMusicAsync(string filePath)
+    void OnLive(object? sender, EventArgs e)
     {
-        MusicPattern? pattern = null;
+        if (_isLiveRunning || _server.HasClient) return;
+        if (_cboAudioDev.SelectedItem is not MMDevice dev) return;
+
+        _isLiveRunning = true;
+        _btnLive.Enabled = false;
+        _lblTrack.Text = "Starting live capture...";
+
+        _state.SetStrength('A', 60);
+        _state.SetStrength('B', 60);
+        _state.Stop('A');
+        _state.Stop('B');
+
+        _liveCapture = new LiveCapture(_state, dev);
+        _liveCapture.Stopped += () => BeginInvoke(StopLive);
+        _liveCapture.Start();
+
+        _lblTrack.Text = "Live capture";
+        RefreshButtonStates();
+    }
+
+    void StopLive()
+    {
+        if (_liveCapture != null)
+        {
+            try { _liveCapture.Stop(); } catch { }
+            try { _liveCapture.Dispose(); } catch { }
+            _liveCapture = null;
+        }
+
+        if (_isLiveRunning)
+        {
+            _isLiveRunning = false;
+            if (!IsDisposed)
+            {
+                _lblTrack.Text = "";
+                RefreshButtonStates();
+            }
+        }
+    }
+
+    string _patternName = "";
+    CancellationTokenSource? _patternCts;
+
+    void OnPattern(object? sender, EventArgs e)
+    {
+        if (_isPatternRunning || _server.HasClient) return;
+
+        var url = ShowInputDialog("Paste xToys pattern URL:", "Pattern Import");
+        if (string.IsNullOrWhiteSpace(url)) return;
+
+        _isPatternRunning = true;
+        _btnPattern.Enabled = false;
+        _lblTrack.Text = "Loading pattern...";
+
+        _patternCts = new CancellationTokenSource();
+        Task.Run(() => RunPatternAsync(url, _patternCts.Token));
+    }
+
+    async Task RunPatternAsync(string url, CancellationToken ct)
+    {
+        XToysPattern? pattern = null;
         try
         {
-            var progress = new Progress<int>(pct =>
-            {
-                if (!IsDisposed)
-                    _lblTrack.Text = $"Analyzing... {pct}%  {Path.GetFileName(filePath)}";
-            });
-            pattern = await Task.Run(() => MusicAnalyzer.Analyze(filePath, (IProgress<int>)progress));
+            pattern = await XToysPatternImporter.ImportAsync(url);
         }
         catch (Exception ex)
         {
             BeginInvoke(() =>
             {
-                _lblTrack.Text = $"Analysis failed: {ex.Message}";
-                _isMusicRunning = false;
-                _btnMusic.Enabled = !_server.HasClient;
-                _btnTest.Enabled = !_server.HasClient && !IsTestRunning;
+                _lblTrack.Text = $"Pattern failed: {ex.Message?.Split('\n')[0]}";
+                _isPatternRunning = false;
+                RefreshButtonStates();
             });
             return;
         }
 
-        _musicTotalTime = pattern.Duration;
+        _patternName = pattern.Name;
 
-        // Set a moderate strength ceiling for music
         _state.SetStrength('A', 60);
         _state.SetStrength('B', 60);
-
-        // Clear any existing patterns and enqueue all music frames
         _state.Stop('A');
         _state.Stop('B');
-        _state.EnqueueStream('A', pattern.ChannelA);
-        _state.EnqueueStream('B', pattern.ChannelB);
 
-        // Start audio playback + stopwatch simultaneously
-        try
-        {
-            var reader = new AudioFileReader(filePath);
-            _audioOut = new WaveOutEvent();
-            _audioOut.Init(reader);
-            _audioOut.PlaybackStopped += (_, _) => BeginInvoke(StopMusic);
-            _musicStopwatch = Stopwatch.StartNew();
-            _audioOut.Play();
-        }
-        catch (Exception ex)
-        {
-            Console.Error.WriteLine($"[music] playback failed: {ex.Message}");
-            _musicStopwatch = Stopwatch.StartNew();
-        }
+        BeginInvoke(() => _lblTrack.Text = $"Pattern: {_patternName}");
 
-        BeginInvoke(() => _lblTrack.Text = $"Playing  00:00 / {_musicTotalTime:mm\\:ss}  {Path.GetFileName(filePath)}");
+        // Continuously enqueue pattern frames at 100ms per frame
+        int idx = 0;
+        while (!ct.IsCancellationRequested && _isPatternRunning)
+        {
+            var frameA = pattern.ChannelA[idx];
+            var frameB = pattern.ChannelB[idx];
+            _state.EnqueueStream('A', new[] { frameA });
+            _state.EnqueueStream('B', new[] { frameB });
+            idx = (idx + 1) % pattern.ChannelA.Count;
+
+            try { await Task.Delay(100, ct); } catch (OperationCanceledException) { break; }
+        }
     }
 
-    void StopMusic()
+    void StopPattern()
     {
-        if (_audioOut != null)
-        {
-            try { _audioOut.Stop(); } catch { }
-            try { _audioOut.Dispose(); } catch { }
-            _audioOut = null;
-        }
-        _musicStopwatch = null;
+        _patternCts?.Cancel();
+        _patternCts = null;
 
-        if (_isMusicRunning)
+        if (_isPatternRunning)
         {
-            _isMusicRunning = false;
+            _isPatternRunning = false;
             if (!IsDisposed)
             {
                 _lblTrack.Text = "";
-                _btnMusic.Enabled = !_server.HasClient;
+                RefreshButtonStates();
             }
         }
     }
 
+    string ShowInputDialog(string prompt, string title)
+    {
+        using var dlg = new Form
+        {
+            Text = title,
+            FormBorderStyle = FormBorderStyle.FixedDialog,
+            ClientSize = new Size(380, 100),
+            StartPosition = FormStartPosition.CenterParent,
+            MaximizeBox = false,
+            MinimizeBox = false
+        };
+        var lbl = new Label { Text = prompt, Location = new Point(12, 12), Size = new Size(356, 20) };
+        var txt = new TextBox { Location = new Point(12, 36), Size = new Size(356, 22) };
+        var ok = new Button { Text = "OK", DialogResult = DialogResult.OK, Location = new Point(200, 66), Size = new Size(80, 24) };
+        var cancel = new Button { Text = "Cancel", DialogResult = DialogResult.Cancel, Location = new Point(288, 66), Size = new Size(80, 24) };
+        dlg.Controls.AddRange(new Control[] { lbl, txt, ok, cancel });
+        dlg.AcceptButton = ok;
+        dlg.CancelButton = cancel;
+        return dlg.ShowDialog(this) == DialogResult.OK ? txt.Text.Trim() : "";
+    }
+
     void UpdateTrayIcon()
     {
         var newState = _state.IsSignaling ? "hot"
@@ -598,6 +739,23 @@ public class MainForm : Form
         };
     }
 
+    static void FixTrackbarKeys(TrackBar tb)
+    {
+        tb.KeyDown += (s, e) =>
+        {
+            if (s is not TrackBar t) return;
+            int step = e.KeyCode == Keys.Up || e.KeyCode == Keys.Down ? 1
+                     : e.KeyCode == Keys.PageUp || e.KeyCode == Keys.PageDown ? 10
+                     : 0;
+            if (step == 0) return;
+            if (e.KeyCode is Keys.Up or Keys.PageUp or Keys.Home)
+                t.Value = Math.Min(t.Maximum, t.Value + (e.KeyCode == Keys.Home ? t.Maximum : step));
+            else
+                t.Value = Math.Max(t.Minimum, t.Value - (e.KeyCode == Keys.End ? t.Maximum : step));
+            e.Handled = true;
+        };
+    }
+
     static Icon CreateVoltageIcon(Color boltColor)
     {
         const int sz = 32;

MusicAnalyzer.cs

@@ -1,135 +1,21 @@
 using System.Numerics;
 using FftSharp;
-using NAudio.Wave;
 
 namespace Substation;
 
-public record MusicPattern(List<WaveFrame> ChannelA, List<WaveFrame> ChannelB, TimeSpan Duration);
-
 public static class MusicAnalyzer
 {
-    const int SampleRate = 44100;
-    const int WindowSize = 2048;
-    const int HopSize = 1024;
-    const double TickDuration = 0.1; // 100ms per e-stim frame
+    public const int WindowSize = 2048;
+    public const int HopSize = 1024;
+    public const double TickDuration = 0.1;
 
-    // Frequency band boundaries (Hz)
     const double RhythmLow = 20, RhythmHigh = 250;
     const double MelodyLow = 300, MelodyHigh = 4000;
 
-    public static MusicPattern Analyze(string mp3Path, IProgress<int>? progress = null)
+    public static (double rhythmEnergy, double rhythmFlux, double melodyEnergy, double melodyFreq)
+        ExtractFeatures(double[] magnitude, double[]? prevRhythmMag, int sampleRate)
     {
-        var samples = DecodeToMono(mp3Path);
-        var duration = TimeSpan.FromSeconds((double)samples.Length / SampleRate);
-
-        var tickCount = (int)Math.Ceiling((double)samples.Length / SampleRate / TickDuration);
-        var channelA = new List<WaveFrame>(tickCount);
-        var channelB = new List<WaveFrame>(tickCount);
-
-        var window = new FftSharp.Windows.Hanning();
-        var buffer = new double[WindowSize];
-        int fftsPerTick = (int)Math.Round(TickDuration * SampleRate / HopSize);
-
-        double[]? prevRhythmMag = null;
-        double maxFlux = 0;
-        double maxMelodyEnergy = 0;
-
-        // First pass: collect per-tick features
-        var tickFeatures = new List<TickFeature>(tickCount);
-        int pos = 0;
-        int fftIndex = 0;
-
-        while (pos + WindowSize <= samples.Length)
-        {
-            for (int i = 0; i < WindowSize; i++)
-                buffer[i] = samples[pos + i];
-
-            window.ApplyInPlace(buffer);
-            var spectrum = FFT.Forward(buffer);
-            var mag = FFT.Magnitude(spectrum);
-
-            var (rhythmEnergy, rhythmFlux, melodyEnergy, melodyFreq) =
-                ExtractFeatures(mag, prevRhythmMag);
-
-            if (rhythmFlux > maxFlux) maxFlux = rhythmFlux;
-            if (melodyEnergy > maxMelodyEnergy) maxMelodyEnergy = melodyEnergy;
-
-            prevRhythmMag = mag;
-
-            int tickIdx = fftIndex / Math.Max(1, fftsPerTick);
-            while (tickFeatures.Count <= tickIdx)
-                tickFeatures.Add(new TickFeature());
-
-            var tf = tickFeatures[tickIdx];
-            tf.RhythmFlux = Math.Max(tf.RhythmFlux, rhythmFlux);
-            tf.MelodyEnergy += melodyEnergy;
-            tf.MelodyFreqSamples.Add(melodyFreq);
-            tf.MelodyCount++;
-
-            pos += HopSize;
-            fftIndex++;
-
-            if (progress != null && fftIndex % 50 == 0)
-            {
-                var pct = (int)((double)pos / samples.Length * 100);
-                progress.Report(pct);
-            }
-        }
-
-        progress?.Report(100);
-
-        // Second pass: normalize and build WaveFrames
-        const int rhythmFreqMs = 150; // ~7Hz deep pulse
-
-        foreach (var tf in tickFeatures)
-        {
-            // Channel A: rhythm onset
-            double normalizedFlux = maxFlux > 0 ? tf.RhythmFlux / maxFlux : 0;
-            int onsetIntensity = (int)Math.Round(normalizedFlux * 100);
-            // Sub-tick attack/decay shape
-            var intA = new[]
-            {
-                (byte)Math.Clamp(onsetIntensity, 0, 100),
-                (byte)Math.Clamp(onsetIntensity * 6 / 10, 0, 100),
-                (byte)Math.Clamp(onsetIntensity * 3 / 10, 0, 100),
-                (byte)0
-            };
-            var freqA = Freq.Compress4(new[] { rhythmFreqMs, rhythmFreqMs, rhythmFreqMs, rhythmFreqMs });
-            channelA.Add(new WaveFrame(freqA, intA));
-
-            // Channel B: melody
-            double avgEnergy = tf.MelodyCount > 0 ? tf.MelodyEnergy / tf.MelodyCount : 0;
-            double normalizedEnergy = maxMelodyEnergy > 0 ? avgEnergy / maxMelodyEnergy : 0;
-            int melodyIntensity = (int)Math.Round(normalizedEnergy * 80); // cap at 80 for comfort
-            melodyIntensity = Math.Clamp(melodyIntensity, 0, 100);
-
-            // Weighted average dominant frequency
-            double weightedFreq = 0;
-            double totalWeight = 0;
-            foreach (var f in tf.MelodyFreqSamples)
-            {
-                weightedFreq += f * f; // weight by energy (freq already squared mag)
-                totalWeight += f;
-            }
-            double avgMelodyHz = totalWeight > 0 ? weightedFreq / totalWeight : 500;
-            int estimsMs = MapPitchToPeriod(avgMelodyHz);
-
-            var intB = new[]
-            {
-                (byte)melodyIntensity, (byte)melodyIntensity,
-                (byte)melodyIntensity, (byte)melodyIntensity
-            };
-            var freqB = Freq.Compress4(new[] { estimsMs, estimsMs, estimsMs, estimsMs });
-            channelB.Add(new WaveFrame(freqB, intB));
-        }
-
-        return new MusicPattern(channelA, channelB, duration);
-    }
-
-    static (double rhythmEnergy, double rhythmFlux, double melodyEnergy, double melodyFreq) ExtractFeatures(
-        double[] magnitude, double[]? prevRhythmMag)
-    {
-        double binWidth = (double)SampleRate / WindowSize;
+        double binWidth = (double)sampleRate / WindowSize;
         int rhythmLoBin = (int)(RhythmLow / binWidth);
         int rhythmHiBin = (int)(RhythmHigh / binWidth);
         int melodyLoBin = (int)(MelodyLow / binWidth);
@@ -172,7 +58,7 @@ public static class MusicAnalyzer
         return (rhythmEnergy, rhythmFlux, melodyEnergy, melodyFreq);
     }
 
-    static int MapPitchToPeriod(double hz)
+    public static int MapPitchToPeriod(double hz)
     {
         // Map melody frequency (300-4000Hz) to e-stim period (10-1000ms)
         // Logarithmic mapping: low notes → deep, high notes → buzzy
@@ -185,36 +71,51 @@ public static class MusicAnalyzer
         return Math.Clamp(ms, 10, 1000);
     }
 
-    static double[] DecodeToMono(string mp3Path)
-    {
-        using var reader = new Mp3FileReader(mp3Path);
-        var format = new WaveFormat(SampleRate, 16, 1);
-        using var resampler = new MediaFoundationResampler(reader, format);
-        resampler.ResamplerQuality = 60;
-
-        var sampleList = new List<float>();
-        var buffer = new byte[SampleRate * 2]; // 1s worth of 16-bit mono
-        int read;
-        while ((read = resampler.Read(buffer, 0, buffer.Length)) > 0)
-        {
-            for (int i = 0; i < read; i += 2)
-            {
-                short sample = (short)(buffer[i] | (buffer[i + 1] << 8));
-                sampleList.Add(sample / 32768f);
-            }
-        }
-
-        var result = new double[sampleList.Count];
-        for (int i = 0; i < sampleList.Count; i++)
-            result[i] = sampleList[i];
-        return result;
-    }
-
-    class TickFeature
+    public class TickFeature
     {
         public double RhythmFlux;
         public double MelodyEnergy;
         public double MelodyCount;
         public readonly List<double> MelodyFreqSamples = new();
     }
+
+    public static (WaveFrame chA, WaveFrame chB) BuildWaveFrame(TickFeature tf, double maxFlux, double maxMelodyEnergy)
+    {
+        const int rhythmFreqMs = 150;
+
+        double normalizedFlux = maxFlux > 0 ? tf.RhythmFlux / maxFlux : 0;
+        int onsetIntensity = (int)Math.Round(normalizedFlux * 100);
+        var intA = new[]
+        {
+            (byte)Math.Clamp(onsetIntensity, 0, 100),
+            (byte)Math.Clamp(onsetIntensity * 6 / 10, 0, 100),
+            (byte)Math.Clamp(onsetIntensity * 3 / 10, 0, 100),
+            (byte)0
+        };
+        var freqA = Freq.Compress4(new[] { rhythmFreqMs, rhythmFreqMs, rhythmFreqMs, rhythmFreqMs });
+
+        double avgEnergy = tf.MelodyCount > 0 ? tf.MelodyEnergy / tf.MelodyCount : 0;
+        double normalizedEnergy = maxMelodyEnergy > 0 ? avgEnergy / maxMelodyEnergy : 0;
+        int melodyIntensity = (int)Math.Round(normalizedEnergy * 80);
+        melodyIntensity = Math.Clamp(melodyIntensity, 0, 100);
+
+        double weightedFreq = 0;
+        double totalWeight = 0;
+        foreach (var f in tf.MelodyFreqSamples)
+        {
+            weightedFreq += f * f;
+            totalWeight += f;
+        }
+        double avgMelodyHz = totalWeight > 0 ? weightedFreq / totalWeight : 500;
+        int estimsMs = MapPitchToPeriod(avgMelodyHz);
+
+        var intB = new[]
+        {
+            (byte)melodyIntensity, (byte)melodyIntensity,
+            (byte)melodyIntensity, (byte)melodyIntensity
+        };
+        var freqB = Freq.Compress4(new[] { estimsMs, estimsMs, estimsMs, estimsMs });
+
+        return (new WaveFrame(freqA, intA), new WaveFrame(freqB, intB));
+    }
 }

NOTES.md

@@ -129,3 +129,28 @@ web game / userscript  ──WS──>  Substation  ──BLE──>  Coyote 3.0
 ```
 
 Build: `dotnet run -c Release`
+
+## xToys pattern import
+
+Paste a URL like `https://xtoys.app/patterns/-OuhuHOuY1AlPPoCJlzc` into the Pattern dialog.
+The app fetches the pattern once from `https://xtoys.app/api/getPatternv2`, evaluates it
+locally, and plays it as a continuous loop. No ongoing API calls.
+
+### xToys script-v3 slider parameters
+
+From pattern analysis:
+
+- **A CH** (0.5–10): Divides the pattern between channels. If A=1 and B=2, then 2/3 of
+  the pattern goes to channel B. Controls the "hold" duration on channel A.
+- **B CH** (0.5–10): Same division for channel B. Controls the "pause" duration.
+- **Ramp** (0.5–5): Applies a smoothness filter to transitions. Higher = slower ramps.
+- **Min Freq** (0–100): Low cutoff on frequency values. No idea why.
+- **Min Level** (0–100): Low cutoff on intensity values. Floor that's held during "pause".
+
+### Frequency mapping
+
+xToys frequency is 0–100 (percentage). Mapped to e-stim period:
+- 0% = 1000ms (1Hz, deep thump)
+- 100% = 10ms (100Hz, buzzy)
+
+Formula: `period_ms = 1000 - 9.9 * freq_pct`

State.cs

@@ -25,6 +25,7 @@ public class State
     public int MaxB = 200;
     public LimitMode LimitModeA = LimitMode.Clamp;
     public LimitMode LimitModeB = LimitMode.Clamp;
+    public bool SwapChannels;
 
     public void SetLimitA(int max, LimitMode mode)
     {
@@ -129,6 +130,19 @@ public class State
             LastIntensityA = hasA ? (intA[0] + intA[1] + intA[2] + intA[3]) / 4 : 0;
             LastIntensityB = hasB ? (intB[0] + intB[1] + intB[2] + intB[3]) / 4 : 0;
 
+            if (SwapChannels)
+            {
+                (valA, valB) = (valB, valA);
+                (modeA, modeB) = (modeB, modeA);
+                (freqA, freqB) = (freqB, freqA);
+                (intA, intB) = (intB, intA);
+                (LastSentA, LastSentB) = (LastSentB, LastSentA);
+                (LastFreqA, LastFreqB) = (LastFreqB, LastFreqA);
+                (LastIntA, LastIntB) = (LastIntB, LastIntA);
+                (LastActiveA, LastActiveB) = (LastActiveB, LastActiveA);
+                (LastIntensityA, LastIntensityB) = (LastIntensityB, LastIntensityA);
+            }
+
             return (modeA, valA, modeB, valB, freqA, intA, freqB, intB);
         }
     }

Substation.csproj

@@ -11,9 +11,9 @@
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
     <AssemblyName>Substation</AssemblyName>
     <RootNamespace>Substation</RootNamespace>
-    <Version>0.1.6</Version>
-    <AssemblyVersion>0.1.6</AssemblyVersion>
-    <FileVersion>0.1.6</FileVersion>
+    <Version>0.2.0</Version>
+    <AssemblyVersion>0.2.0</AssemblyVersion>
+    <FileVersion>0.2.0</FileVersion>
   </PropertyGroup>
 
   <ItemGroup>

XToysPattern.cs

@@ -0,0 +1,162 @@
+using System.Net.Http;
+using System.Text;
+using System.Text.Json;
+using System.Text.RegularExpressions;
+
+namespace Substation;
+
+public record XToysPattern(string Name, List<WaveFrame> ChannelA, List<WaveFrame> ChannelB);
+
+public static class XToysPatternImporter
+{
+    static readonly HttpClient Http = new();
+
+    public static async Task<XToysPattern> ImportAsync(string url)
+    {
+        var patternId = ExtractPatternId(url);
+        if (patternId == null)
+            throw new ArgumentException("Could not extract pattern ID from URL. Expected format: https://xtoys.app/patterns/<ID>");
+
+        var body = JsonSerializer.Serialize(new { data = new { patternID = patternId } });
+        var content = new StringContent(body, Encoding.UTF8, "application/json");
+        var response = await Http.PostAsync("https://xtoys.app/api/getPatternv2", content);
+        response.EnsureSuccessStatusCode();
+
+        var json = await response.Content.ReadAsStringAsync();
+        return Parse(json);
+    }
+
+    static int FreqPctToMs(byte freqPct)
+    {
+        // xToys frequency: 0% = deep (1000ms), 100% = buzzy (10ms)
+        // freqPct is the raw 0-100 value from the pattern (already clamped in EvaluatePattern)
+        return (int)Math.Round(1000 - 9.9 * freqPct);
+    }
+
+    static string? ExtractPatternId(string url)
+    {
+        var match = Regex.Match(url, @"/patterns/([A-Za-z0-9_-]+)");
+        return match.Success ? match.Groups[1].Value : null;
+    }
+
+    static XToysPattern Parse(string json)
+    {
+        using var doc = JsonDocument.Parse(json);
+
+        var pattern = doc.RootElement.GetProperty("result").GetProperty("pattern");
+        var name = pattern.GetProperty("name").GetString() ?? "Unknown";
+        var patternData = pattern.GetProperty("patternData");
+
+        // Resolve slider defaults
+        var sliders = new Dictionary<string, double>();
+        if (patternData.TryGetProperty("ma", out var ma))
+        {
+            foreach (var slider in ma.EnumerateArray())
+            {
+                var key = slider.GetProperty("key").GetString()!;
+                var value = slider.GetProperty("value").GetDouble();
+                sliders[key] = value;
+            }
+        }
+
+        // Evaluate patterns to per-tick value arrays
+        var int1 = EvaluatePattern(patternData, "Int1", sliders);
+        var int2 = EvaluatePattern(patternData, "Int2", sliders);
+        var freq1 = EvaluatePattern(patternData, "Freq1", sliders);
+        var freq2 = EvaluatePattern(patternData, "Freq2", sliders);
+
+        // All patterns in a group should have the same total duration.
+        // Use the max length to be safe.
+        int tickCount = Math.Max(int1.Length, Math.Max(int2.Length, Math.Max(freq1.Length, freq2.Length)));
+
+        var channelA = new List<WaveFrame>(tickCount);
+        var channelB = new List<WaveFrame>(tickCount);
+
+        for (int i = 0; i < tickCount; i++)
+        {
+            byte intA = i < int1.Length ? int1[i] : (byte)0;
+            byte intB = i < int2.Length ? int2[i] : (byte)0;
+            // Freq patterns output 0-100 (percentage). Map: 0% = 1000ms deep, 100% = 10ms buzzy.
+            byte freqA = i < freq1.Length ? Freq.Compress(FreqPctToMs(freq1[i])) : Freq.Compress(10);
+            byte freqB = i < freq2.Length ? Freq.Compress(FreqPctToMs(freq2[i])) : Freq.Compress(10);
+
+            channelA.Add(new WaveFrame(
+                new[] { freqA, freqA, freqA, freqA },
+                new[] { intA, intA, intA, intA }));
+
+            channelB.Add(new WaveFrame(
+                new[] { freqB, freqB, freqB, freqB },
+                new[] { intB, intB, intB, intB }));
+        }
+
+        return new XToysPattern(name, channelA, channelB);
+    }
+
+    static byte[] EvaluatePattern(JsonElement patternData, string patternName, Dictionary<string, double> sliders)
+    {
+        if (!patternData.TryGetProperty("patterns", out var patterns))
+            return Array.Empty<byte>();
+        if (!patterns.TryGetProperty(patternName, out var patternArr))
+            return Array.Empty<byte>();
+
+        var values = new List<byte>();
+        double lastEnd = 0;
+
+        foreach (var loop in patternArr.EnumerateArray())
+        {
+            var steps = loop.GetProperty("steps");
+            foreach (var step in steps.EnumerateArray())
+            {
+                var type = step.GetProperty("type").GetString() ?? "straight";
+                var time = ResolveExpr(GetStepValue(step, "time"), sliders);
+                var startVal = step.TryGetProperty("start", out var s)
+                    ? (s.ValueKind == JsonValueKind.Null ? lastEnd : ResolveExpr(GetStepValue(step, "start"), sliders))
+                    : lastEnd;
+                var endVal = ResolveExpr(GetStepValue(step, "end"), sliders);
+
+                int ticks = Math.Max(1, (int)Math.Round(time / 0.1));
+
+                for (int t = 0; t < ticks; t++)
+                {
+                    double frac = (double)t / ticks;
+                    double v;
+                    if (type == "sine")
+                        v = startVal + (endVal - startVal) * (1 - Math.Cos(frac * Math.PI)) / 2;
+                    else
+                        v = startVal + (endVal - startVal) * frac;
+
+                    values.Add((byte)Math.Clamp((int)Math.Round(v), 0, 100));
+                }
+
+                lastEnd = endVal;
+            }
+        }
+
+        return values.ToArray();
+    }
+
+    static string GetStepValue(JsonElement step, string propName)
+    {
+        if (!step.TryGetProperty(propName, out var el))
+            return "0";
+        return el.ValueKind switch
+        {
+            JsonValueKind.String => el.GetString() ?? "0",
+            JsonValueKind.Number => el.GetDouble().ToString(),
+            _ => "0"
+        };
+    }
+
+    static double ResolveExpr(string expr, Dictionary<string, double> sliders)
+    {
+        // Replace {var} references, then evaluate simple expressions like "ramp/2"
+        var resolved = Regex.Replace(expr, @"\{(\w+)\}", m =>
+            sliders.TryGetValue(m.Groups[1].Value, out var val) ? val.ToString() : "0");
+
+        // Parse simple arithmetic: number, or number/number
+        var parts = resolved.Split('/');
+        if (parts.Length == 2 && double.TryParse(parts[0], out var a) && double.TryParse(parts[1], out var b))
+            return a / b;
+        return double.TryParse(resolved, out var result) ? result : 0;
+    }
+}