rvsttd: increase fade-out to 25ms

This reverts commit 84474731e7.

Robovoice.App/MainForm.Designer.cs

@@ -9,21 +9,15 @@ partial class MainForm
     private TextBox txtPttKey = null!;
     private Label lblVoice = null!;
     private ComboBox cmbVoice = null!;
-    private Button btnTestVoice = null!;
     private Button btnManageVoices = null!;
     private Label lblOutput = null!;
     private ComboBox cmbOutput = null!;
-    private Label lblFile = null!;
-    private Button btnBrowseFile = null!;
-    private Label lblFileName = null!;
     private Label lblServer = null!;
     private TextBox txtSttEndpoint = null!;
-    private Label lblLineStatus = null!;
+    private Button btnLock = null!;
     private RichTextBox txtLog = null!;
     private CheckBox chkMinimizeToTray = null!;
     private Button btnClearLog = null!;
-    private Label lblTextInput = null!;
-    private TextBox txtTextInput = null!;
     private Label lblNoise = null!;
     private TrackBar trkNoise = null!;
     private Label lblNoiseVal = null!;
@@ -49,21 +43,15 @@ partial class MainForm
         txtPttKey = new TextBox();
         lblVoice = new Label();
         cmbVoice = new ComboBox();
-        btnTestVoice = new Button();
         btnManageVoices = new Button();
         lblOutput = new Label();
         cmbOutput = new ComboBox();
-        lblFile = new Label();
-        btnBrowseFile = new Button();
-        lblFileName = new Label();
         lblServer = new Label();
         txtSttEndpoint = new TextBox();
-        lblLineStatus = new Label();
+        btnLock = new Button();
         txtLog = new RichTextBox();
         chkMinimizeToTray = new CheckBox();
         btnClearLog = new Button();
-        lblTextInput = new Label();
-        txtTextInput = new TextBox();
         lblNoise = new Label();
         trkNoise = new TrackBar();
         lblNoiseVal = new Label();
@@ -100,64 +88,38 @@ partial class MainForm
         cmbVoice.Size = new Size(200, 23);
         cmbVoice.DropDownStyle = ComboBoxStyle.DropDownList;
 
-        // btnTestVoice
-        btnTestVoice.Text = "Test";
-        btnTestVoice.Location = new Point(423, 11);
-        btnTestVoice.Size = new Size(45, 25);
-        btnTestVoice.UseVisualStyleBackColor = true;
-
         // btnManageVoices
         btnManageVoices.Text = "Add/Remove...";
-        btnManageVoices.Location = new Point(474, 11);
+        btnManageVoices.Location = new Point(423, 11);
         btnManageVoices.Size = new Size(95, 25);
         btnManageVoices.UseVisualStyleBackColor = true;
 
         // lblOutput
         lblOutput.Text = "Output:";
-        lblOutput.Location = new Point(580, 15);
+        lblOutput.Location = new Point(530, 15);
         lblOutput.Size = new Size(50, 23);
         lblOutput.TextAlign = ContentAlignment.MiddleLeft;
 
         // cmbOutput
-        cmbOutput.Location = new Point(633, 12);
+        cmbOutput.Location = new Point(583, 12);
-        cmbOutput.Size = new Size(180, 23);
+        cmbOutput.Size = new Size(150, 23);
         cmbOutput.DropDownStyle = ComboBoxStyle.DropDownList;
 
-        // lblFile
-        lblFile.Text = "Text File:";
-        lblFile.Location = new Point(12, 48);
-        lblFile.Size = new Size(60, 23);
-        lblFile.TextAlign = ContentAlignment.MiddleLeft;
-
-        // btnBrowseFile
-        btnBrowseFile.Text = "Browse...";
-        btnBrowseFile.Location = new Point(75, 45);
-        btnBrowseFile.Size = new Size(75, 25);
-        btnBrowseFile.UseVisualStyleBackColor = true;
-
-        // lblFileName
-        lblFileName.Text = "(none)";
-        lblFileName.Location = new Point(155, 48);
-        lblFileName.Size = new Size(280, 23);
-        lblFileName.TextAlign = ContentAlignment.MiddleLeft;
-        lblFileName.ForeColor = Color.Gray;
-
         // lblServer
         lblServer.Text = "STT:";
-        lblServer.Location = new Point(440, 48);
+        lblServer.Location = new Point(12, 48);
         lblServer.Size = new Size(35, 23);
         lblServer.TextAlign = ContentAlignment.MiddleLeft;
 
         // txtSttEndpoint
-        txtSttEndpoint.Location = new Point(478, 45);
+        txtSttEndpoint.Location = new Point(50, 45);
-        txtSttEndpoint.Size = new Size(185, 23);
+        txtSttEndpoint.Size = new Size(200, 23);
 
-        // lblLineStatus
+        // btnLock
-        lblLineStatus.Text = "";
+        btnLock.Text = "Lock Model";
-        lblLineStatus.Location = new Point(645, 48);
+        btnLock.Location = new Point(260, 44);
-        lblLineStatus.Size = new Size(160, 23);
+        btnLock.Size = new Size(90, 25);
-        lblLineStatus.TextAlign = ContentAlignment.MiddleRight;
+        btnLock.UseVisualStyleBackColor = true;
-        lblLineStatus.ForeColor = Color.DarkBlue;
 
         // lblNoise
         lblNoise.Text = "Noise:";
@@ -165,7 +127,7 @@ partial class MainForm
         lblNoise.Size = new Size(40, 23);
         lblNoise.TextAlign = ContentAlignment.MiddleLeft;
 
-        // trkNoise (0-1000 → 0.0-1.0, default 667)
+        // trkNoise
         trkNoise.Location = new Point(52, 78);
         trkNoise.Size = new Size(120, 45);
         trkNoise.Minimum = 0;
@@ -186,7 +148,7 @@ partial class MainForm
         lblSpeed.Size = new Size(40, 23);
         lblSpeed.TextAlign = ContentAlignment.MiddleLeft;
 
-        // trkSpeed (50-300 → 0.5-3.0, default 100)
+        // trkSpeed
         trkSpeed.Location = new Point(260, 78);
         trkSpeed.Size = new Size(120, 45);
         trkSpeed.Minimum = 50;
@@ -207,7 +169,7 @@ partial class MainForm
         lblNoiseW.Size = new Size(45, 23);
         lblNoiseW.TextAlign = ContentAlignment.MiddleLeft;
 
-        // trkNoiseW (0-1000 → 0.0-1.0, default 800)
+        // trkNoiseW
         trkNoiseW.Location = new Point(475, 78);
         trkNoiseW.Size = new Size(120, 45);
         trkNoiseW.Minimum = 0;
@@ -223,19 +185,8 @@ partial class MainForm
         lblNoiseWVal.TextAlign = ContentAlignment.MiddleLeft;
 
         // txtLog
-        txtLog.Location = new Point(12, 149);
+        txtLog.Location = new Point(12, 121);
-        txtLog.Size = new Size(800, 310);
+        txtLog.Size = new Size(800, 338);
-
-        // lblTextInput
-        lblTextInput.Text = "Text:";
-        lblTextInput.Location = new Point(12, 121);
-        lblTextInput.Size = new Size(35, 23);
-        lblTextInput.TextAlign = ContentAlignment.MiddleLeft;
-
-        // txtTextInput
-        txtTextInput.Location = new Point(50, 118);
-        txtTextInput.Size = new Size(762, 23);
-
         txtLog.ReadOnly = true;
         txtLog.Font = new Font("Consolas", 9F);
         txtLog.BackColor = Color.FromArgb(30, 30, 30);
@@ -261,16 +212,12 @@ partial class MainForm
         Controls.Add(txtPttKey);
         Controls.Add(lblVoice);
         Controls.Add(cmbVoice);
-        Controls.Add(btnTestVoice);
         Controls.Add(btnManageVoices);
         Controls.Add(lblOutput);
         Controls.Add(cmbOutput);
-        Controls.Add(lblFile);
-        Controls.Add(btnBrowseFile);
-        Controls.Add(lblFileName);
         Controls.Add(lblServer);
         Controls.Add(txtSttEndpoint);
-        Controls.Add(lblLineStatus);
+        Controls.Add(btnLock);
         Controls.Add(lblNoise);
         Controls.Add(trkNoise);
         Controls.Add(lblNoiseVal);
@@ -280,8 +227,6 @@ partial class MainForm
         Controls.Add(lblNoiseW);
         Controls.Add(trkNoiseW);
         Controls.Add(lblNoiseWVal);
-        Controls.Add(lblTextInput);
-        Controls.Add(txtTextInput);
         Controls.Add(txtLog);
         Controls.Add(chkMinimizeToTray);
         Controls.Add(btnClearLog);

Robovoice.App/MainForm.cs

@@ -17,10 +17,11 @@ internal sealed partial class MainForm : Form
     private LibPiperTtsEngine? _tts;
     private AudioOutput? _audioOutput;
     private TcpSttSource? _sttSource;
-    private Orchestrator? _orchestrator;
+    private VoicePipeline? _pipeline;
     private PttHotkey? _pttHotkey;
     private NotifyIcon? _trayIcon;
     private bool _trayInit;
+    private bool _locked;
 
     public MainForm()
     {
@@ -65,14 +66,11 @@ internal sealed partial class MainForm : Form
             chkMinimizeToTray.Checked = _config.MinimizeToTray;
             txtSttEndpoint.Text = _config.SttEndpoint;
 
-            btnBrowseFile.Click += OnBrowseFile;
-            btnTestVoice.Click += OnTestVoice;
             btnManageVoices.Click += OnManageVoices;
             btnClearLog.Click += (_, _) => txtLog.Clear();
+            btnLock.Click += OnLockToggle;
             txtPttKey.Enter += OnPttKeyFocus;
             txtPttKey.KeyDown += OnPttKeyDown;
-            cmbOutput.SelectedIndexChanged += OnOutputChanged;
-            cmbVoice.SelectedIndexChanged += OnVoiceChanged;
             txtSttEndpoint.Leave += OnSttEndpointChanged;
 
             trkNoise.Scroll += OnSliderScroll;
@@ -90,10 +88,8 @@ internal sealed partial class MainForm : Form
         }
         catch (Exception ex)
         {
-            System.Diagnostics.Debug.WriteLine($"OnLoad failed: {ex}");
+            Debug.WriteLine($"OnLoad failed: {ex}");
         }
-
-        BeginInvoke(async () => await InitializeEngineAsync());
     }
 
     private Keys _pttKey = Keys.F8;
@@ -216,7 +212,21 @@ internal sealed partial class MainForm : Form
             cmbOutput.SelectedIndex = 0;
     }
 
-    private async Task InitializeEngineAsync()
+    // ─── Lock / Release ────────────────────────────────────────────────────
+
+    private async void OnLockToggle(object? sender, EventArgs e)
+    {
+        if (_locked)
+        {
+            ReleaseModel();
+        }
+        else
+        {
+            await LockModelAsync();
+        }
+    }
+
+    private async Task LockModelAsync()
     {
         if (cmbVoice.SelectedItem is not string voiceName)
         {
@@ -237,43 +247,97 @@ internal sealed partial class MainForm : Form
             return;
         }
 
+        btnLock.Enabled = false;
         Log($"Loading voice: {voiceName}...");
-        _audioOutput?.Dispose();
-        if (_tts is not null)
-            await _tts.DisposeAsync();
 
+        try
+        {
             _tts = new LibPiperTtsEngine(
                 modelPath,
                 _espeakDataPath,
                 noiseScale: trkNoise.Value / 1000.0f,
                 lengthScale: trkSpeed.Value / 100.0f,
                 noiseWScale: trkNoiseW.Value / 1000.0f);
+
+            await Task.Run(() => _tts.InitializeAsync());
+            Log($"TTS ready (sample rate: {_tts.SampleRate} Hz)");
+
             _audioOutput = new AudioOutput();
 
-        try
-        {
-            if (_sttSource is null)
-            {
             _sttSource = new TcpSttSource { Endpoint = txtSttEndpoint.Text, Log = Log };
+            _sttSource.TranscriptReceived += OnTranscript;
             await _sttSource.StartAsync();
-            }
 
-            if (_orchestrator is not null)
+            _pipeline = new VoicePipeline(_tts, _audioOutput, Log)
-                await _orchestrator.DisposeAsync();
-            _orchestrator = new Orchestrator(_tts, _audioOutput, _sttSource, Log)
             {
                 OutputDeviceName = cmbOutput.SelectedItem as string ?? string.Empty,
             };
+            _pipeline.Start();
+
+            _locked = true;
+            SetControlsLocked(true);
+            btnLock.Text = "Release Model";
+            btnLock.Enabled = true;
 
-            await _orchestrator.InitializeTtsAsync();
-            Log("Engine ready. Press PTT to send to STT server.");
             SetupHotkey();
+            Log("Model locked. Press PTT to talk.");
         }
         catch (Exception ex)
         {
-            Log($"Init failed: {ex.Message}");
+            Log($"Lock failed: {ex.Message}");
+            btnLock.Enabled = true;
+            _tts?.DisposeAsync().AsTask().Wait();
+            _tts = null;
+            _audioOutput?.Dispose();
+            _audioOutput = null;
+            if (_sttSource is not null)
+            {
+                _sttSource.TranscriptReceived -= OnTranscript;
+                _sttSource.DisposeAsync().AsTask().Wait();
+                _sttSource = null;
             }
         }
+    }
+
+    private void ReleaseModel()
+    {
+        if (!_locked) return;
+
+        _pttHotkey?.Dispose();
+        _pttHotkey = null;
+
+        if (_sttSource is not null)
+        {
+            _sttSource.TranscriptReceived -= OnTranscript;
+            _sttSource.DisposeAsync().AsTask().Wait();
+            _sttSource = null;
+        }
+
+        _pipeline?.Dispose();
+        _pipeline = null;
+
+        // VoicePipeline.Dispose calls _tts.DisposeAsync and _audioOutput.Dispose
+        _tts = null;
+        _audioOutput = null;
+
+        _locked = false;
+        SetControlsLocked(false);
+        btnLock.Text = "Lock Model";
+        Log("Model released.");
+    }
+
+    private void SetControlsLocked(bool locked)
+    {
+        cmbVoice.Enabled = !locked;
+        cmbOutput.Enabled = !locked;
+        trkNoise.Enabled = !locked;
+        trkSpeed.Enabled = !locked;
+        trkNoiseW.Enabled = !locked;
+        txtSttEndpoint.Enabled = !locked;
+        btnManageVoices.Enabled = !locked;
+    }
+
+    // ─── PTT ────────────────────────────────────────────────────────────────
 
     private void SetupHotkey()
     {
@@ -287,86 +351,56 @@ internal sealed partial class MainForm : Form
 
     private void OnPttPressed(object? sender, EventArgs e)
     {
-        Log("PTT pressed");
+        _pipeline?.OnPttPressed();
-        _orchestrator?.NotifyPttPressed();
-        try
-        {
         _sttSource?.SendOn();
     }
-        catch (Exception ex)
-        {
-            Log($"SendOn failed: {ex.Message}");
-        }
-    }
 
     private void OnPttReleased(object? sender, EventArgs e)
-    {
-        Log("PTT released");
-        try
     {
         _sttSource?.SendOff();
+        _pipeline?.OnPttReleased();
     }
-        catch (Exception ex)
+
+    // ─── STT transcript → pipeline ──────────────────────────────────────────
+
+    private void OnTranscript(object? sender, TranscriptEventArgs e)
     {
-            Log($"SendOff failed: {ex.Message}");
+        if (_pipeline is null || !_locked) return;
+
+        var msg = e.Message;
+        if (msg.Type == TranscriptType.Partial)
+        {
+            if (!string.IsNullOrWhiteSpace(msg.Text))
+            {
+                Log($"SEGMENT: \"{msg.Text}\"");
+                _pipeline.EnqueueSegment(msg.Text);
+            }
+        }
+        else
+        {
+            if (!string.IsNullOrWhiteSpace(msg.Text))
+            {
+                Log($"FINAL: \"{msg.Text}\"");
+                _pipeline.EnqueueFinal(msg.Text);
+            }
+            else
+            {
+                Log("FINAL: (empty)");
+                _pipeline.EnqueueFinal("");
+            }
         }
     }
 
-    private void OnBrowseFile(object? sender, EventArgs e)
+    // ─── Voice manager ─────────────────────────────────────────────────────
-    {
-        using var dlg = new OpenFileDialog
-        {
-            Filter = "Text files (*.txt)|*.txt|All files (*.*)|*.*",
-            Title = "Select a text file to speak",
-        };
-
-        if (dlg.ShowDialog() == DialogResult.OK)
-        {
-            string text = File.ReadAllText(dlg.FileName);
-            lblFileName.Text = Path.GetFileName(dlg.FileName);
-            lblFileName.ForeColor = Color.Black;
-            Log($"Loaded: {dlg.FileName} ({text.Length} chars)");
-            _ = _orchestrator?.SynthesizeAsync(text);
-        }
-    }
-
-    private void OnTestVoice(object? sender, EventArgs e)
-    {
-        if (_orchestrator is null)
-        {
-            Log("Engine not initialized.");
-            return;
-        }
-
-        if (cmbVoice.SelectedItem is not string voiceName)
-        {
-            Log("No voice selected.");
-            return;
-        }
-
-        if (!VoiceCatalogue.IsVoiceInstalled(_voicesDir, voiceName))
-        {
-            Log($"Voice '{voiceName}' is not installed. Use Add/Remove to download it.");
-            return;
-        }
-
-        string text = txtTextInput.Text.Trim();
-        if (string.IsNullOrEmpty(text))
-            text = "Hello, this is a voice test.";
-
-        btnTestVoice.Enabled = false;
-        try
-        {
-            _ = _orchestrator.SynthesizeAsync(text);
-        }
-        finally
-        {
-            btnTestVoice.Enabled = true;
-        }
-    }
 
     private void OnManageVoices(object? sender, EventArgs e)
     {
+        if (_locked)
+        {
+            Log("Release the model before managing voices.");
+            return;
+        }
+
         string currentVoice = cmbVoice.SelectedItem as string ?? string.Empty;
         using var dlg = new VoiceManagerForm(_voicesDir, currentVoice);
         dlg.ShowDialog(this);
@@ -384,31 +418,9 @@ internal sealed partial class MainForm : Form
         }
 
         SaveConfig();
-        _ = InitializeEngineAsync();
     }
 
-    private void OnVoiceChanged(object? sender, EventArgs e)
+    // ─── Slider / endpoint ─────────────────────────────────────────────────
-    {
-        btnTestVoice.Enabled = cmbVoice.SelectedItem is string voiceName
-            && VoiceCatalogue.IsVoiceInstalled(_voicesDir, voiceName);
-
-        if (cmbVoice.SelectedItem is string name)
-        {
-            SaveConfig();
-            _ = ReinitializeEngineAsync(name);
-        }
-    }
-
-    private async Task ReinitializeEngineAsync(string voiceName)
-    {
-        if (!VoiceCatalogue.IsVoiceInstalled(_voicesDir, voiceName))
-        {
-            btnTestVoice.Enabled = false;
-            return;
-        }
-
-        await InitializeEngineAsync();
-    }
 
     private void OnSliderScroll(object? sender, EventArgs e)
     {
@@ -420,32 +432,15 @@ internal sealed partial class MainForm : Form
     private void OnSliderReleased(object? sender, MouseEventArgs e)
     {
         SaveConfig();
-        if (cmbVoice.SelectedItem is string name && VoiceCatalogue.IsVoiceInstalled(_voicesDir, name))
-        {
-            _ = InitializeEngineAsync();
-        }
     }
 
-    private void OnOutputChanged(object? sender, EventArgs e)
+    private void OnSttEndpointChanged(object? sender, EventArgs e)
-    {
-        if (_orchestrator is not null)
-            _orchestrator.OutputDeviceName = cmbOutput.SelectedItem as string ?? string.Empty;
-        Log($"Output device: {_orchestrator?.OutputDeviceName}");
-        SaveConfig();
-    }
-
-    private async void OnSttEndpointChanged(object? sender, EventArgs e)
     {
         _config.SttEndpoint = txtSttEndpoint.Text;
         SaveConfig();
+    }
 
-        if (_sttSource is not null)
+    // ─── Tray ──────────────────────────────────────────────────────────────
-        {
-            await _sttSource.DisposeAsync();
-            _sttSource = null;
-            await InitializeEngineAsync();
-        }
-    }
 
     private void SetupTray()
     {
@@ -503,6 +498,8 @@ internal sealed partial class MainForm : Form
         Activate();
     }
 
+    // ─── Config ────────────────────────────────────────────────────────────
+
     private void SaveConfig()
     {
         _config.Voice = cmbVoice.SelectedItem as string ?? string.Empty;
@@ -516,6 +513,8 @@ internal sealed partial class MainForm : Form
         _config.Save();
     }
 
+    // ─── Logging ───────────────────────────────────────────────────────────
+
     private void Log(string message)
     {
         if (IsDisposed) return;
@@ -530,12 +529,13 @@ internal sealed partial class MainForm : Form
         txtLog.ScrollToCaret();
     }
 
+    // ─── Shutdown ──────────────────────────────────────────────────────────
+
     private void OnFormClosing(object? sender, FormClosingEventArgs e)
     {
         _pttHotkey?.Dispose();
         _trayIcon!.Visible = false;
-        _orchestrator?.DisposeAsync().AsTask().Wait(2000);
+        ReleaseModel();
-        _sttSource?.DisposeAsync().AsTask().Wait(2000);
         SaveConfig();
     }
 }

Robovoice.App/Orchestrator.cs

@@ -1,257 +0,0 @@
-using Robovoice.Core;
-using Robovoice.Tts.LibPiper;
-
-namespace Robovoice.App;
-
-internal sealed class Orchestrator : IAsyncDisposable
-{
-    private readonly LibPiperTtsEngine _tts;
-    private readonly AudioOutput _audioOutput;
-    private readonly ISttSource _sttSource;
-    private readonly Action<string> _log;
-    private CancellationTokenSource? _currentCts;
-    private bool _disposed;
-
-    private readonly object _stateLock = new();
-    private readonly Queue<string> _pendingTexts = new();
-    private readonly List<float[]> _audioBuffer = new();
-    private int _bufferSampleRate;
-    private bool _playing;
-    private Task? _synthTask;
-    private CancellationTokenSource? _synthCts;
-
-    public string OutputDeviceName { get; set; } = string.Empty;
-
-    public Orchestrator(
-        LibPiperTtsEngine tts,
-        AudioOutput audioOutput,
-        ISttSource sttSource,
-        Action<string> log)
-    {
-        _tts = tts;
-        _audioOutput = audioOutput;
-        _audioOutput.Log = log;
-        _sttSource = sttSource;
-        _log = log;
-        _sttSource.TranscriptReceived += OnTranscript;
-    }
-
-    private void OnTranscript(object? sender, TranscriptEventArgs e)
-    {
-        var msg = e.Message;
-
-        lock (_stateLock)
-        {
-            if (msg.Type == TranscriptType.Partial)
-            {
-                if (!string.IsNullOrWhiteSpace(msg.Text))
-                {
-                    _log($"SEGMENT: \"{msg.Text}\" ({msg.Text.Length} chars)");
-                    _pendingTexts.Enqueue(msg.Text);
-                    EnsureSynthTask();
-                }
-            }
-            else
-            {
-                if (!string.IsNullOrWhiteSpace(msg.Text))
-                {
-                    _log($"FINAL: \"{msg.Text}\" ({msg.Text.Length} chars)");
-                    _pendingTexts.Enqueue(msg.Text);
-                    EnsureSynthTask();
-                }
-                else
-                {
-                    _log("FINAL: (empty)");
-                }
-
-                TransitionToPlaying();
-            }
-        }
-    }
-
-    private void TransitionToPlaying()
-    {
-        if (_playing)
-            return;
-
-        if (_audioBuffer.Count == 0)
-        {
-            if (_synthTask is null || _synthTask.IsCompleted)
-            {
-                _log("TTS: nothing to play");
-            }
-            return;
-        }
-
-        _playing = true;
-
-        int sampleRate = _bufferSampleRate;
-        var chunks = _audioBuffer.ToList();
-        _audioBuffer.Clear();
-
-        _log($"TTS: playing {chunks.Count} buffered chunks ({sampleRate} Hz)");
-
-        _audioOutput.Start(sampleRate, OutputDeviceName);
-        foreach (var samples in chunks)
-        {
-            _audioOutput.WriteSamples(samples);
-        }
-    }
-
-    private void EnsureSynthTask()
-    {
-        if (_synthTask is not null && !_synthTask.IsCompleted)
-            return;
-
-        _synthCts?.Cancel();
-        _synthCts = new CancellationTokenSource();
-        _synthTask = SynthLoopAsync(_synthCts.Token);
-    }
-
-    private async Task SynthLoopAsync(CancellationToken ct)
-    {
-        while (true)
-        {
-            string text;
-            lock (_stateLock)
-            {
-                if (_pendingTexts.Count == 0)
-                    break;
-                text = _pendingTexts.Dequeue();
-            }
-
-            try
-            {
-                await foreach (var chunk in _tts.SynthesizeAsync(text, ct))
-                {
-                    lock (_stateLock)
-                    {
-                        if (_playing)
-                        {
-                            _audioOutput.WriteSamples(chunk.Samples);
-                        }
-                        else
-                        {
-                            _bufferSampleRate = chunk.SampleRate;
-                            _audioBuffer.Add(chunk.Samples);
-                        }
-                    }
-                }
-            }
-            catch (OperationCanceledException)
-            {
-                break;
-            }
-            catch (Exception ex)
-            {
-                _log($"TTS error: {ex.Message}");
-            }
-        }
-
-        lock (_stateLock)
-        {
-            if (_playing)
-            {
-                _audioOutput.Flush();
-                _log("TTS: synthesis complete, flushed");
-            }
-        }
-    }
-
-    public void NotifyPttPressed()
-    {
-        lock (_stateLock)
-        {
-            _synthCts?.Cancel();
-            _synthCts?.Dispose();
-            _synthTask = null;
-
-            if (_playing)
-            {
-                _audioOutput.Stop();
-                _playing = false;
-            }
-
-            _pendingTexts.Clear();
-            _audioBuffer.Clear();
-            _bufferSampleRate = 0;
-        }
-    }
-
-    public async Task InitializeTtsAsync()
-    {
-        _log("Initializing TTS engine...");
-        await Task.Run(() => _tts.InitializeAsync());
-        _log($"TTS ready (sample rate: {_tts.SampleRate} Hz)");
-    }
-
-    public async Task SynthesizeAsync(string text)
-    {
-        _currentCts?.Cancel();
-        _currentCts = new CancellationTokenSource();
-        var ct = _currentCts.Token;
-
-        var sw = System.Diagnostics.Stopwatch.StartNew();
-        _log($"Speak: \"{text}\" ({text.Length} chars)");
-
-        try
-        {
-            bool started = false;
-            int chunkCount = 0;
-            int totalSamples = 0;
-
-            await foreach (var chunk in _tts.SynthesizeAsync(text, ct))
-            {
-                if (!started)
-                {
-                    started = true;
-                    _audioOutput.Start(chunk.SampleRate, OutputDeviceName);
-                    _log($"TTS: first chunk ({sw.ElapsedMilliseconds}ms)");
-                }
-
-                _audioOutput.WriteSamples(chunk.Samples);
-                chunkCount++;
-                totalSamples += chunk.Samples.Length;
-            }
-
-            if (!started)
-            {
-                _log("TTS: no audio produced");
-            }
-            else
-            {
-                _audioOutput.Flush();
-                double durationSec = (double)totalSamples / _tts.SampleRate;
-                _log($"TTS: done ({chunkCount} chunks, {durationSec:F2}s audio, {sw.ElapsedMilliseconds}ms)");
-            }
-        }
-        catch (OperationCanceledException)
-        {
-            _log("TTS: cancelled");
-            _audioOutput.Stop();
-        }
-        catch (Exception ex)
-        {
-            _log($"TTS error: {ex.Message}");
-        }
-
-        sw.Stop();
-    }
-
-    public async ValueTask DisposeAsync()
-    {
-        if (_disposed) return;
-        _disposed = true;
-
-        try { _currentCts?.Cancel(); } catch { }
-        _currentCts?.Dispose();
-
-        try { _synthCts?.Cancel(); } catch { }
-        _synthCts?.Dispose();
-
-        _sttSource.TranscriptReceived -= OnTranscript;
-        await _sttSource.DisposeAsync();
-        await _tts.DisposeAsync();
-        _audioOutput.Dispose();
-    }
-}

Robovoice.App/VoicePipeline.cs

@@ -0,0 +1,187 @@
+using System.Collections.Concurrent;
+using Robovoice.Core;
+using Robovoice.Tts.LibPiper;
+
+namespace Robovoice.App;
+
+internal sealed record TextItem(uint Session, string Text);
+
+internal sealed record AudioItem(uint Session, float[]? Samples);
+
+internal sealed class VoicePipeline : IDisposable
+{
+    private readonly LibPiperTtsEngine _tts;
+    private readonly AudioOutput _audioOutput;
+    private readonly Action<string> _log;
+
+    private BlockingCollection<TextItem> _textQueue = new();
+    private BlockingCollection<AudioItem> _audioQueue = new();
+    private ManualResetEventSlim _gate = new(false);
+    private volatile uint _currentSession;
+    private volatile bool _running;
+
+    private Thread? _synthThread;
+    private Thread? _playerThread;
+    private bool _disposed;
+
+    public string OutputDeviceName { get; set; } = string.Empty;
+
+    public VoicePipeline(
+        LibPiperTtsEngine tts,
+        AudioOutput audioOutput,
+        Action<string> log)
+    {
+        _tts = tts;
+        _audioOutput = audioOutput;
+        _audioOutput.Log = log;
+        _log = log;
+    }
+
+    public void Start()
+    {
+        _running = true;
+        _synthThread = new Thread(SynthLoop) { IsBackground = true, Name = "VoicePipeline-Synth" };
+        _playerThread = new Thread(PlayerLoop) { IsBackground = true, Name = "VoicePipeline-Player" };
+        _synthThread.Start();
+        _playerThread.Start();
+    }
+
+    public void EnqueueSegment(string text)
+    {
+        if (!_running) return;
+        uint session = _currentSession;
+        _textQueue.Add(new TextItem(session, text));
+    }
+
+    public void EnqueueFinal(string text)
+    {
+        if (!_running) return;
+        uint session = _currentSession;
+        if (!string.IsNullOrEmpty(text))
+            _textQueue.Add(new TextItem(session, text));
+        _textQueue.Add(new TextItem(session, ""));
+        _gate.Reset();
+    }
+
+    public void OnPttPressed()
+    {
+        _currentSession++;
+        _gate.Reset();
+        _audioOutput.Stop();
+    }
+
+    public void OnPttReleased()
+    {
+        _gate.Set();
+    }
+
+    private void SynthLoop()
+    {
+        foreach (var item in _textQueue.GetConsumingEnumerable())
+        {
+            if (!_running) break;
+
+            if (item.Session != _currentSession)
+                continue;
+
+            if (item.Text.Length == 0)
+            {
+                // :F sentinel — signal end of utterance to player
+                _audioQueue.Add(new AudioItem(item.Session, null));
+                continue;
+            }
+
+            try
+            {
+                foreach (var chunk in _tts.SynthesizeSync(item.Text))
+                {
+                    if (item.Session != _currentSession)
+                    {
+                        // Session changed mid-synthesis — drain piper cleanly
+                        _tts.SynthesizeDrain();
+                        break;
+                    }
+
+                    _audioQueue.Add(new AudioItem(item.Session, chunk.Samples));
+                }
+            }
+            catch (Exception ex)
+            {
+                _log($"TTS error: {ex.Message}");
+            }
+        }
+    }
+
+    private void PlayerLoop()
+    {
+        while (_running)
+        {
+            _gate.Wait();
+            if (!_running) break;
+
+            // Drain stale items, then wait for real audio for current session
+            AudioItem firstItem = default!;
+            while (_running)
+            {
+                try { firstItem = _audioQueue.Take(); }
+                catch (InvalidOperationException) { return; }
+
+                if (firstItem.Session != _currentSession)
+                    continue;
+
+                break;
+            }
+
+            if (!_running) break;
+
+            if (firstItem.Samples == null)
+            {
+                // :F with no audio — nothing to play
+                _gate.Reset();
+                continue;
+            }
+
+            _audioOutput.Start(_tts.SampleRate, OutputDeviceName);
+            _audioOutput.WriteSamples(firstItem.Samples);
+            _log($"TTS: playback started (session {firstItem.Session})");
+
+            foreach (var item in _audioQueue.GetConsumingEnumerable())
+            {
+                if (!_running) break;
+
+                if (item.Session != _currentSession)
+                    break;
+
+                if (item.Samples == null)
+                    break;
+
+                _audioOutput.WriteSamples(item.Samples);
+            }
+
+            _audioOutput.Flush();
+            _log("TTS: playback finished");
+            _gate.Reset();
+        }
+    }
+
+    public void Dispose()
+    {
+        if (_disposed) return;
+        _disposed = true;
+        _running = false;
+
+        _gate.Set();
+        _textQueue.CompleteAdding();
+        _audioQueue.CompleteAdding();
+
+        _synthThread?.Join(5000);
+        _playerThread?.Join(5000);
+
+        _textQueue.Dispose();
+        _audioQueue.Dispose();
+        _gate.Dispose();
+
+        _tts.DisposeAsync().AsTask().Wait();
+        _audioOutput.Dispose();
+    }
+}

Robovoice.Stt.Tcp/TcpSttSource.cs

@@ -9,10 +9,9 @@ public sealed class TcpSttSource : ISttSource
 {
     private TcpClient? _tcp;
     private NetworkStream? _stream;
-    private StreamReader? _reader;
     private StreamWriter? _writer;
-    private CancellationTokenSource? _cts;
+    private Thread? _connectThread;
-    private Task? _runTask;
+    private volatile bool _running;
     private readonly object _sendLock = new();
     private uint _session;
     private bool _disposed;
@@ -26,107 +25,157 @@ public sealed class TcpSttSource : ISttSource
     public Task StartAsync(CancellationToken ct = default)
     {
         ObjectDisposedException.ThrowIf(_disposed, this);
-        if (_cts is not null)
+        if (_running)
             return Task.CompletedTask;
 
-        _cts = CancellationTokenSource.CreateLinkedTokenSource(ct);
+        _running = true;
-        _runTask = RunAsync(_cts.Token);
+        _connectThread = new Thread(ConnectLoop) { IsBackground = true, Name = "TcpSttSource-Connect" };
+        _connectThread.Start();
+
         return Task.CompletedTask;
     }
 
-    public async Task StopAsync(CancellationToken ct = default)
+    public Task StopAsync(CancellationToken ct = default)
     {
-        if (_cts is not null)
+        _running = false;
-            _cts.Cancel();
 
-        CleanupConnection();
+        lock (_sendLock)
-
-        if (_runTask is not null)
         {
-            try { await _runTask.WaitAsync(ct); }
+            _writer?.Dispose();
-            catch { }
+            _stream?.Dispose();
-            _runTask = null;
+            _tcp?.Close();
+            _writer = null;
+            _stream = null;
+            _tcp = null;
         }
 
-        _cts?.Dispose();
+        // Threads are background — they'll die when the process exits.
-        _cts = null;
+        // Closing the socket unblocks any pending Read.
+        _connectThread?.Join(1000);
+
+        return Task.CompletedTask;
     }
 
-    private async Task RunAsync(CancellationToken ct)
+    private void ConnectLoop()
     {
-        while (!ct.IsCancellationRequested)
+        while (_running)
         {
             IPEndPoint? endpoint = ParseEndpoint(Endpoint);
             if (endpoint is null)
             {
                 Log?.Invoke($"STT: invalid endpoint '{Endpoint}'");
-                try { await Task.Delay(3000, ct); } catch { break; }
+                SleepInterruptible(3000);
                 continue;
             }
 
             try
             {
-                _tcp = new TcpClient();
+                var tcp = new TcpClient();
-                using var connectCts = CancellationTokenSource.CreateLinkedTokenSource(ct);
+                tcp.Connect(endpoint.Address, endpoint.Port);
-                connectCts.CancelAfter(TimeSpan.FromSeconds(5));
+                tcp.NoDelay = true;
-                await _tcp.ConnectAsync(endpoint.Address, endpoint.Port, connectCts.Token);
 
-                _stream = _tcp.GetStream();
+                lock (_sendLock)
-                _reader = new StreamReader(_stream, Encoding.UTF8);
+                {
-                _writer = new StreamWriter(_stream, Encoding.UTF8) { AutoFlush = true };
+                    _tcp = tcp;
+                    _stream = tcp.GetStream();
+                    _writer = new StreamWriter(_stream, new UTF8Encoding(false)) { AutoFlush = true };
+                }
 
                 Log?.Invoke($"STT: connected to {Endpoint}");
 
-                await ReceiveLoopAsync(ct);
+                // Blocking receive loop — runs until disconnected or stopped.
-            }
+                ReceiveLoop();
-            catch (OperationCanceledException)
+
-            {
+                Log?.Invoke("STT: disconnected");
-                break;
             }
             catch (Exception ex)
             {
+                if (_running)
                     Log?.Invoke($"STT: connection failed ({ex.Message}), retrying...");
             }
             finally
             {
-                CleanupConnection();
+                lock (_sendLock)
-            }
-
-            if (!ct.IsCancellationRequested)
                 {
-                try { await Task.Delay(3000, ct); }
+                    _writer?.Dispose();
-                catch (OperationCanceledException) { break; }
+                    _stream?.Dispose();
-            }
+                    _tcp?.Close();
+                    _writer = null;
+                    _stream = null;
+                    _tcp = null;
                 }
             }
 
-    private async Task ReceiveLoopAsync(CancellationToken ct)
+            if (_running)
+                SleepInterruptible(3000);
+        }
+    }
+
+    private void ReceiveLoop()
     {
-        while (!ct.IsCancellationRequested && _reader is not null)
+        byte[] buffer = new byte[4096];
+        StringBuilder lineBuf = new();
+
+        while (_running)
         {
-            string? line;
+            NetworkStream? stream;
+            lock (_sendLock)
+            {
+                stream = _stream;
+            }
+
+            if (stream is null)
+                break;
+
+            int bytesRead;
             try
             {
-                line = await _reader.ReadLineAsync(ct);
+                bytesRead = stream.Read(buffer, 0, buffer.Length);
             }
             catch
             {
                 break;
             }
 
-            if (line is null)
+            if (bytesRead == 0)
                 break;
 
-            TranscriptMessage? message = ParseReply(line);
+            for (int i = 0; i < bytesRead; i++)
-            if (message is null)
+            {
-                continue;
+                byte b = buffer[i];
+                if (b == '\n')
+                {
+                    string line = lineBuf.ToString().TrimEnd('\r');
+                    lineBuf.Clear();
 
+                    TranscriptMessage? message = ParseReply(line);
+                    if (message is not null)
+                    {
                         TranscriptReceived?.Invoke(this, new TranscriptEventArgs
                         {
                             Message = message,
                         });
                     }
                 }
+                else
+                {
+                    lineBuf.Append((char)b);
+                }
+            }
+        }
+    }
+
+    private void SleepInterruptible(int ms)
+    {
+        int slice = 100;
+        int waited = 0;
+        while (_running && waited < ms)
+        {
+            int chunk = Math.Min(slice, ms - waited);
+            Thread.Sleep(chunk);
+            waited += chunk;
+        }
+    }
 
     public void SendOn()
     {
@@ -157,21 +206,6 @@ public sealed class TcpSttSource : ISttSource
         }
     }
 
-    private void CleanupConnection()
-    {
-        lock (_sendLock)
-        {
-            _writer?.Dispose();
-            _reader?.Dispose();
-            _stream?.Dispose();
-            _tcp?.Dispose();
-            _writer = null;
-            _reader = null;
-            _stream = null;
-            _tcp = null;
-        }
-    }
-
     private static IPEndPoint? ParseEndpoint(string endpoint)
     {
         int colon = endpoint.LastIndexOf(':');
@@ -224,33 +258,34 @@ public sealed class TcpSttSource : ISttSource
         {
             string rest = line["F ".Length..];
             int space = rest.IndexOf(' ');
+
             if (space < 0)
-                return null;
-
-            if (!uint.TryParse(rest[..space], out uint session))
-                return null;
-
-            if (session != _session)
             {
-                Log?.Invoke($"STT: dropping stale reply (session {session} != current {_session})");
+                if (uint.TryParse(rest, out uint session) && session == _session)
+                    return new TranscriptMessage(TranscriptType.Final, string.Empty);
+                return null;
+            }
+
+            if (!uint.TryParse(rest[..space], out uint ses))
+                return null;
+
+            if (ses != _session)
+            {
+                Log?.Invoke($"STT: dropping stale reply (session {ses} != current {_session})");
                 return null;
             }
 
             return new TranscriptMessage(TranscriptType.Final, rest[(space + 1)..]);
         }
 
-        if (line == "F")
-        {
-            return new TranscriptMessage(TranscriptType.Final, string.Empty);
-        }
-
         return null;
     }
 
-    public async ValueTask DisposeAsync()
+    public ValueTask DisposeAsync()
     {
-        if (_disposed) return;
+        if (_disposed) return ValueTask.CompletedTask;
-        await StopAsync();
         _disposed = true;
+        StopAsync();
+        return ValueTask.CompletedTask;
     }
 }

Robovoice.Tts.LibPiper/LibPiperTtsEngine.cs

@@ -120,6 +120,71 @@ public sealed class LibPiperTtsEngine : ITtsEngine
         }
     }
 
+    public IEnumerable<AudioChunk> SynthesizeSync(string text)
+    {
+        ObjectDisposedException.ThrowIf(_disposed, this);
+        if (!_initialized)
+            throw new InvalidOperationException("Engine not initialized.");
+
+        var options = new PiperSynthesizeOptions
+        {
+            SpeakerId = 0,
+            LengthScale = _lengthScale,
+            NoiseScale = _noiseScale,
+            NoiseWScale = _noiseWScale,
+        };
+
+        byte[] textBytes = System.Text.Encoding.UTF8.GetBytes(EnsureTerminator(text) + "\0");
+        GCHandle textPin = GCHandle.Alloc(textBytes, GCHandleType.Pinned);
+        try
+        {
+            int startResult = PiperNative.piper_synthesize_start(
+                _synth, textPin.AddrOfPinnedObject(), in options);
+            if (startResult != PiperNative.PiperOk)
+                throw new InvalidOperationException($"piper_synthesize_start failed: {startResult}");
+
+            while (true)
+            {
+                PiperAudioChunk chunk = default;
+                int result = PiperNative.piper_synthesize_next(_synth, out chunk);
+
+                if (chunk.NumSamples > 0 && chunk.Samples != IntPtr.Zero)
+                {
+                    int numSamples = (int)chunk.NumSamples;
+                    float[] samples = new float[numSamples];
+                    Marshal.Copy(chunk.Samples, samples, 0, numSamples);
+
+                    if (chunk.SampleRate > 0)
+                        _sampleRate = chunk.SampleRate;
+
+                    yield return new AudioChunk(samples, _sampleRate);
+                }
+
+                if (result == PiperNative.PiperDone || chunk.IsLast)
+                    break;
+
+                if (result < 0)
+                    throw new InvalidOperationException($"piper_synthesize_next failed: {result}");
+            }
+        }
+        finally
+        {
+            textPin.Free();
+        }
+    }
+
+    public void SynthesizeDrain()
+    {
+        if (!_initialized || _synth == IntPtr.Zero)
+            return;
+
+        PiperAudioChunk chunk;
+        while (PiperNative.piper_synthesize_next(_synth, out chunk) != PiperNative.PiperDone)
+        {
+            if (chunk.IsLast) break;
+        }
+    }
+
     private static string EnsureTerminator(string text)
     {
         string trimmed = text.TrimEnd();

rvsttd/src/main.rs

@@ -8,6 +8,7 @@ use std::io::{BufRead, BufReader, Write};
 use std::net::{TcpListener, TcpStream};
 use std::path::PathBuf;
 use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::mpsc;
 use std::sync::{Arc, Mutex};
 use std::thread;
 use std::time::{Duration, SystemTime, UNIX_EPOCH};
@@ -69,12 +70,112 @@ fn line_text(line: &transcript_line_t) -> String {
         .into_owned()
 }
 
+fn unix_now() -> u64 {
+    SystemTime::now()
+        .duration_since(UNIX_EPOCH)
+        .unwrap_or_default()
+        .as_secs()
+}
+
+// ─── debug session recorder ──────────────────────────────────────────────
+
+struct DebugRecorder {
+    dir: PathBuf,
+    audio: Vec<f32>,
+    log_lines: Vec<String>,
+}
+
+impl DebugRecorder {
+    fn new(base_dir: &PathBuf) -> Self {
+        let dir = base_dir.join(unix_now().to_string());
+        std::fs::create_dir_all(&dir).ok();
+        Self {
+            dir,
+            audio: Vec::new(),
+            log_lines: Vec::new(),
+        }
+    }
+
+    fn log_event(&mut self, event: &str) {
+        self.log_lines.push(format!("[{}] {}", ts(), event));
+    }
+
+    fn log_segment(&mut self, line: &transcript_line_t, prefix: &str) {
+        let text = line_text(line);
+        let event = format!(
+            "SEGMENT id={} prefix={} is_complete={} start={:.3}s duration={:.3}s text=\"{}\"",
+            line.id, prefix, line.is_complete, line.start_time, line.duration, text
+        );
+        self.log_event(&event);
+    }
+
+    fn add_audio(&mut self, samples: &[f32]) {
+        self.audio.extend_from_slice(samples);
+    }
+
+    fn save(self) {
+        // Write log
+        let log_path = self.dir.join("session.log");
+        match std::fs::File::create(&log_path) {
+            Ok(mut f) => {
+                for line in &self.log_lines {
+                    writeln!(f, "{}", line).ok();
+                }
+            }
+            Err(e) => log(&format!("debug: failed to write log: {}", e)),
+        }
+
+        // Write WAV
+        let wav_path = self.dir.join("audio.wav");
+        match write_wav(&wav_path, &self.audio, SAMPLE_RATE as u32) {
+            Ok(()) => {
+                let secs = self.audio.len() as f64 / SAMPLE_RATE as f64;
+                log(&format!("debug: saved {} ({:.1}s, {} samples)", self.dir.display(), secs, self.audio.len()));
+            }
+            Err(e) => log(&format!("debug: failed to write wav: {}", e)),
+        }
+    }
+}
+
+fn write_wav(path: &PathBuf, samples: &[f32], sample_rate: u32) -> Result<()> {
+    let num_samples = samples.len() as u32;
+    let data_size = num_samples * 4; // f32 = 4 bytes
+    let file_size = 44 + data_size;
+
+    let mut f = std::fs::File::create(path)?;
+    // RIFF header
+    f.write_all(b"RIFF")?;
+    f.write_all(&(file_size - 8).to_le_bytes())?;
+    f.write_all(b"WAVE")?;
+    // fmt chunk
+    f.write_all(b"fmt ")?;
+    f.write_all(&16u32.to_le_bytes())?;       // chunk size
+    f.write_all(&3u16.to_le_bytes())?;         // IEEE float
+    f.write_all(&1u16.to_le_bytes())?;         // mono
+    f.write_all(&sample_rate.to_le_bytes())?;
+    f.write_all(&(sample_rate * 4).to_le_bytes())?; // byte rate
+    f.write_all(&4u16.to_le_bytes())?;         // block align
+    f.write_all(&32u16.to_le_bytes())?;        // bits per sample
+    // data chunk
+    f.write_all(b"data")?;
+    f.write_all(&data_size.to_le_bytes())?;
+
+    // Convert f32 samples to little-endian bytes
+    let mut bytes = Vec::with_capacity(data_size as usize);
+    for &s in samples {
+        bytes.extend_from_slice(&s.to_le_bytes());
+    }
+    f.write_all(&bytes)?;
+    Ok(())
+}
+
 // ─── shared state ─────────────────────────────────────────────────────────
 
 struct Shared {
     writer: Mutex<TcpStream>,
     session_id: u64,
     transcriber_handle: i32,
+    debug_dir: Option<PathBuf>,
 }
 
 impl Shared {
@@ -100,23 +201,26 @@ struct Session {
     stop_signal: Arc<AtomicBool>,
     aborted: Arc<AtomicBool>,
     transcriber: thread::JoinHandle<()>,
-    cpal_stream: cpal::Stream,
+    cpal_stream: Option<cpal::Stream>,
     stream_handle: i32,
 }
 
 impl Session {
-    fn stop(self) {
+    fn stop(mut self) {
+        // Signal transcriber to exit main loop, then wait for it to drain
+        // trailing audio + final flush. cpal stream stays alive during drain.
         self.stop_signal.store(true, Ordering::SeqCst);
-        drop(self.cpal_stream);
         self.transcriber.join().ok();
+        // Now safe to kill ALSA — transcriber is done
+        self.cpal_stream.take();
         unsafe { moonshine_free_stream(self.shared.transcriber_handle, self.stream_handle) };
     }
 
-    fn abort(self) {
+    fn abort(mut self) {
-        self.stop_signal.store(true, Ordering::SeqCst);
         self.aborted.store(true, Ordering::SeqCst);
-        drop(self.cpal_stream);
+        self.stop_signal.store(true, Ordering::SeqCst);
         self.transcriber.join().ok();
+        self.cpal_stream.take();
         unsafe { moonshine_free_stream(self.shared.transcriber_handle, self.stream_handle) };
     }
 }
@@ -134,12 +238,12 @@ fn start_session(shared: Arc<Shared>) -> Option<Session> {
         return None;
     }
 
-    let audio_buf: Arc<Mutex<Vec<f32>>> = Arc::new(Mutex::new(Vec::new()));
+    let (tx, rx) = mpsc::channel::<Vec<f32>>();
     let stop_signal = Arc::new(AtomicBool::new(false));
     let aborted = Arc::new(AtomicBool::new(false));
 
-    let cpal_stream = match start_cpal(audio_buf.clone(), stop_signal.clone()) {
+    let cpal_stream = match start_cpal(tx) {
-        Ok(s) => s,
+        Ok(s) => Some(s),
         Err(e) => {
             log(&format!("cpal failed: {}", e));
             unsafe { moonshine_free_stream(shared.transcriber_handle, stream_handle) };
@@ -152,7 +256,7 @@ fn start_session(shared: Arc<Shared>) -> Option<Session> {
     let aborted_clone = aborted.clone();
 
     let transcriber = thread::spawn(move || {
-        transcriber_loop(shared_clone, audio_buf, stop_signal_clone, aborted_clone, stream_handle);
+        transcriber_loop(shared_clone, rx, stop_signal_clone, aborted_clone, stream_handle);
     });
 
     Some(Session {
@@ -167,7 +271,7 @@ fn start_session(shared: Arc<Shared>) -> Option<Session> {
 
 fn transcriber_loop(
     shared: Arc<Shared>,
-    audio_buf: Arc<Mutex<Vec<f32>>>,
+    rx: mpsc::Receiver<Vec<f32>>,
     stop_signal: Arc<AtomicBool>,
     aborted: Arc<AtomicBool>,
     stream_handle: i32,
@@ -175,16 +279,22 @@ fn transcriber_loop(
     let handle = shared.transcriber_handle;
     let mut sent_ids: HashSet<u64> = HashSet::new();
 
-    while !stop_signal.load(Ordering::SeqCst) {
+    // Debug recorder (if enabled)
-        let chunk = {
+    let mut recorder = shared.debug_dir.as_ref().map(|_| DebugRecorder::new(
-            let mut buf = audio_buf.lock().unwrap();
+        &shared.debug_dir.as_ref().unwrap().join(shared.session_id.to_string()),
-            if buf.is_empty() {
+    ));
-                drop(buf);
+
-                thread::sleep(Duration::from_millis(5));
+    if let Some(ref mut r) = recorder {
-                continue;
+        r.log_event(&format!("session {} started", shared.session_id));
+    }
+
+    // Main loop: process audio until stop_signal
+    while !stop_signal.load(Ordering::SeqCst) {
+        match rx.recv_timeout(Duration::from_millis(100)) {
+            Ok(chunk) => {
+                if let Some(ref mut r) = recorder {
+                    r.add_audio(&chunk);
                 }
-            std::mem::take(&mut *buf)
-        };
 
                 unsafe {
                     moonshine_transcribe_add_audio_to_stream(
@@ -200,31 +310,80 @@ fn transcriber_loop(
                     continue;
                 }
 
+                if let Some(ref mut r) = recorder {
+                    log_transcript_lines(r, t_ptr);
+                }
+
                 send_new_segments(&shared, t_ptr, &mut sent_ids, "P");
             }
+            Err(mpsc::RecvTimeoutError::Timeout) => continue,
+            Err(mpsc::RecvTimeoutError::Disconnected) => break,
+        }
+    }
+
+    // Drain trailing audio from ALSA buffer (cpal stream still alive).
+    // Fixed 100ms window — cpal delivers every ~50ms (800 samples @ 16kHz),
+    // so this captures 1-2 more callbacks worth of trailing audio.
+    // Hold one chunk back so we can apply a fade-out to the very last one.
+    let drain_deadline = std::time::Instant::now() + Duration::from_millis(100);
+    let mut held_chunk: Option<Vec<f32>> = None;
+    while std::time::Instant::now() < drain_deadline {
+        match rx.recv_timeout(drain_deadline - std::time::Instant::now()) {
+            Ok(chunk) => {
+                // Feed previously held chunk to Moonshine + recorder (no fade)
+                if let Some(prev) = held_chunk.take() {
+                    if let Some(ref mut r) = recorder {
+                        r.add_audio(&prev);
+                    }
+                    unsafe {
+                        moonshine_transcribe_add_audio_to_stream(
+                            handle, stream_handle,
+                            prev.as_ptr(), prev.len() as u64,
+                            SAMPLE_RATE, 0,
+                        );
+                    }
+                }
+                held_chunk = Some(chunk);
+            }
+            Err(mpsc::RecvTimeoutError::Timeout) => break,
+            Err(mpsc::RecvTimeoutError::Disconnected) => break,
+        }
+    }
+
+    // Apply 5ms fade-out to the last chunk, then feed to both Moonshine and recorder
+    if let Some(mut chunk) = held_chunk.take() {
+        let fade_samples = (SAMPLE_RATE as usize * 25) / 1000; // 25ms
+        if chunk.len() > fade_samples {
+            let start = chunk.len() - fade_samples;
+            for i in 0..fade_samples {
+                let t = 1.0 - (i as f32 / fade_samples as f32);
+                chunk[start + i] *= t;
+            }
+        }
+
+        if let Some(ref mut r) = recorder {
+            r.add_audio(&chunk);
+        }
+        unsafe {
+            moonshine_transcribe_add_audio_to_stream(
+                handle, stream_handle,
+                chunk.as_ptr(), chunk.len() as u64,
+                SAMPLE_RATE, 0,
+            );
+        }
+    }
 
     // If aborted (new session took over), skip final flush entirely
     if aborted.load(Ordering::SeqCst) {
         unsafe { moonshine_stop_stream(handle, stream_handle) };
         log(&format!("Session {} aborted, skipping final flush", shared.session_id));
+        if let Some(mut r) = recorder {
+            r.log_event("aborted (new session took over)");
+            r.save();
+        }
         return;
     }
 
-    // Drain remaining audio
-    let remaining = {
-        let mut buf = audio_buf.lock().unwrap();
-        std::mem::take(&mut *buf)
-    };
-    if !remaining.is_empty() {
-        unsafe {
-            moonshine_transcribe_add_audio_to_stream(
-                handle, stream_handle,
-                remaining.as_ptr(), remaining.len() as u64,
-                SAMPLE_RATE, 0,
-            );
-        }
-    }
-
     // Final flush
     unsafe { moonshine_stop_stream(handle, stream_handle) };
     let mut t_ptr: *mut transcript_t = std::ptr::null_mut();
@@ -234,6 +393,10 @@ fn transcriber_loop(
         let t = unsafe { &*t_ptr };
         let mut new_segments: Vec<String> = Vec::new();
 
+        if let Some(ref mut r) = recorder {
+            log_transcript_lines(r, t_ptr);
+        }
+
         for i in 0..t.line_count as usize {
             let line = unsafe { &*t.lines.add(i) };
             if line.text.is_null() || line.is_complete == 0 {
@@ -255,10 +418,32 @@ fn transcriber_loop(
             for (i, text) in new_segments.iter().enumerate() {
                 let prefix = if i == last { "F" } else { "P" };
                 shared.send_msg(prefix, text);
+                if let Some(ref mut r) = recorder {
+                    r.log_event(&format!("TX {} \"{}\"", prefix, text));
+                }
             }
         }
     } else {
         shared.send_msg("F", "");
+        if let Some(ref mut r) = recorder {
+            r.log_event("TX F (empty)");
+        }
+    }
+
+    if let Some(mut r) = recorder {
+        r.log_event("session ended");
+        r.save();
+    }
+}
+
+fn log_transcript_lines(recorder: &mut DebugRecorder, t_ptr: *const transcript_t) {
+    let t = unsafe { &*t_ptr };
+    for i in 0..t.line_count as usize {
+        let line = unsafe { &*t.lines.add(i) };
+        if line.text.is_null() {
+            continue;
+        }
+        recorder.log_segment(line, if line.is_complete != 0 { "complete" } else { "partial" });
     }
 }
 
@@ -289,8 +474,7 @@ fn send_new_segments(
 // ─── cpal ─────────────────────────────────────────────────────────────────
 
 fn start_cpal(
-    audio_buf: Arc<Mutex<Vec<f32>>>,
+    tx: mpsc::Sender<Vec<f32>>,
-    stop_signal: Arc<AtomicBool>,
 ) -> Result<cpal::Stream> {
     let host = cpal::default_host();
     let dev = host
@@ -314,6 +498,7 @@ fn start_cpal(
         config.channels = 1;
     }
     config.sample_rate = SampleRate(16000);
+    config.buffer_size = cpal::BufferSize::Fixed(800);
 
     let err_fn = |e: cpal::StreamError| log(&format!("cpal error: {}", e));
 
@@ -321,9 +506,7 @@ fn start_cpal(
         SampleFormat::F32 => dev.build_input_stream(
             &config,
             move |data: &[f32], _: &_| {
-                if !stop_signal.load(Ordering::Relaxed) {
+                let _ = tx.send(data.to_vec());
-                    audio_buf.lock().unwrap().extend_from_slice(data);
-                }
             },
             err_fn,
             None,
@@ -331,9 +514,7 @@ fn start_cpal(
         SampleFormat::I16 => dev.build_input_stream(
             &config,
             move |data: &[i16], _: &_| {
-                if !stop_signal.load(Ordering::Relaxed) {
+                let _ = tx.send(data.iter().map(|&x| x as f32 / 32768.0).collect());
-                    audio_buf.lock().unwrap().extend(data.iter().map(|&x| x as f32 / 32768.0));
-                }
             },
             err_fn,
             None,
@@ -341,9 +522,7 @@ fn start_cpal(
         SampleFormat::U8 => dev.build_input_stream(
             &config,
             move |data: &[u8], _: &_| {
-                if !stop_signal.load(Ordering::Relaxed) {
+                let _ = tx.send(data.iter().map(|&x| (x as f32 - 128.0) / 128.0).collect());
-                    audio_buf.lock().unwrap().extend(data.iter().map(|&x| (x as f32 - 128.0) / 128.0));
-                }
             },
             err_fn,
             None,
@@ -468,17 +647,22 @@ fn main() -> Result<()> {
 
     let mut args = first.into_iter().chain(args);
     let mut model_dir = default_model;
+    let mut debug = false;
 
     while let Some(a) = args.next() {
         match a.as_str() {
             "--model-dir" | "-m" => {
                 model_dir = args.next().unwrap_or(model_dir);
             }
+            "--debug" => {
+                debug = true;
+            }
             "--help" | "-h" => {
-                println!("Usage: rvsttd [--model-dir DIR]");
+                println!("Usage: rvsttd [--model-dir DIR] [--debug]");
                 println!("       rvsttd fetch [DIR]");
                 println!("Listens on TCP {}", BIND_ADDR);
                 println!("Model: medium-streaming (Moonshine)");
+                println!("--debug: save session audio + transcript log to ~/.rvsttd/debug/");
                 println!("'rvsttd fetch' downloads the English medium-streaming model");
                 return Ok(());
             }
@@ -486,6 +670,15 @@ fn main() -> Result<()> {
         }
     }
 
+    let debug_dir = if debug {
+        let d = PathBuf::from(&home).join(".rvsttd").join("debug");
+        std::fs::create_dir_all(&d).ok();
+        log(&format!("Debug mode enabled — sessions saved to {}", d.display()));
+        Some(d)
+    } else {
+        None
+    };
+
     let model_path = std::fs::canonicalize(&model_dir)
         .unwrap_or_else(|_| std::path::PathBuf::from(&model_dir));
 
@@ -547,6 +740,7 @@ fn main() -> Result<()> {
                     writer: Mutex::new(writer_stream.try_clone()?),
                     session_id: new_session_id,
                     transcriber_handle,
+                    debug_dir: debug_dir.clone(),
                 });
 
                 log(&format!("PTT on session {}", new_session_id));