feat(clients): persist input settings, add mic input gain, fix iOS chat + VoiceOver

Input mode (VAD/PTT/Always-On), VAD threshold, and the new mic gain were
applied to the core + UI but never saved, so every relaunch reset to VAD
defaults. Each client now persists them and re-applies on connect:
  - iOS: UserDefaults (SessionState.loadAndApplyVoiceSettings + setter writes)
  - macOS: UserDefaults via MainWindowController didSet + loadPersistedAudioSettings
    (settings window also restores the VAD slider from the stored threshold)
  - Windows: new Models/VoiceSettings.cs (JSON at %AppData%\VoiceCat\voice.json,
    mirrors FeedbackSettings) loaded/applied in MainForm

Add global send-side mic gain API vc_set_input_gain (applied to MIC PCM in
on_capture_frame before the VAD gate, clamped to int16) + Swift/C# bindings,
and a 0-300% (default 100%) mic-volume slider on all three clients.

Fix iOS chat: ChatView called sendText(scope:.channel) with no targetId (0),
so channel messages went nowhere; now passes session.currentChannelId.

Fix iOS per-user tuning for VoiceOver: the tuning sheet was long-press
.contextMenu only (invisible to VoiceOver); UserRow now also exposes the same
buttons via .accessibilityActions (no visual change).

Verified: core builds clean; ctest 24/27 (3 pre-existing teardown crashes,
reproduced with changes stashed); VoiceCatMac + VoiceCatiOS (arm64 sim) build
SUCCEEDED; VoiceCat.Interop dotnet build succeeded. Windows App not built
(WinForms can't build on macOS) — follows existing patterns.

clients/apple/Sources/VoiceCatCore/VoiceCatClient.swift

@@ -409,6 +409,14 @@ public final class VoiceCatClient {
         VoiceCatResult(vc_set_output_volume(handle, gain < 0 ? 0 : gain))
     }
 
+    /// Send-side microphone input gain. Applied to captured MIC PCM before the VAD/PTT gate and
+    /// Opus encode (so boosting a quiet mic also helps it cross the VAD threshold). gain 0.0 =
+    /// silent, 1.0 = unity (default), >1.0 amplifies (clamped to int16). Always LOCAL.
+    @discardableResult
+    public func setInputGain(_ gain: Float) -> VoiceCatResult {
+        VoiceCatResult(vc_set_input_gain(handle, gain < 0 ? 0 : gain))
+    }
+
     // MARK: - AVAudioSession interruption hooks (iOS)
 
     /// Pause miniaudio device I/O. Call when AVAudioSession interruption begins.

clients/apple/iOS/VoiceCatiOS/SessionState.swift

@@ -26,6 +26,7 @@ struct VoiceState {
     var serverDeafened = false
     var inputMode: VoiceCatInputMode = .voiceActivation
     var vadThreshold: Float = 0.025
+    var inputGain: Float = 1.0
     var level: Float = 0.0
     var currentDeviceId: String?
     var localStreamId: UInt32 = 0
@@ -59,6 +60,7 @@ final class SessionState {
         self.client = client
         self.selfUserId = selfUserId
         self.permissions = permissions
+        loadAndApplyVoiceSettings()
         refreshChannels()
         refreshUsers()
         syncSelfChannel()
@@ -336,11 +338,46 @@ final class SessionState {
     func setInputMode(_ mode: VoiceCatInputMode) {
         client.setInputMode(mode)
         voiceState.inputMode = mode
+        UserDefaults.standard.set(Int(mode.rawValue), forKey: DefaultsKey.inputMode)
     }
 
     func setVadThreshold(_ threshold: Float) {
         client.setVadThreshold(threshold)
         voiceState.vadThreshold = threshold
+        UserDefaults.standard.set(threshold, forKey: DefaultsKey.vadThreshold)
+    }
+
+    func setInputGain(_ gain: Float) {
+        client.setInputGain(gain)
+        voiceState.inputGain = gain
+        UserDefaults.standard.set(gain, forKey: DefaultsKey.inputGain)
+    }
+
+    // MARK: - Persisted input settings
+
+    private enum DefaultsKey {
+        static let inputMode    = "voice.inputMode"
+        static let vadThreshold = "voice.vadThreshold"
+        static let inputGain    = "voice.inputGain"
+    }
+
+    /// Restore the saved input mode / VAD threshold / mic gain and push them into the core so a
+    /// relaunch keeps the user's transmission settings instead of resetting to VAD defaults.
+    private func loadAndApplyVoiceSettings() {
+        let d = UserDefaults.standard
+        if d.object(forKey: DefaultsKey.inputMode) != nil {
+            let raw = UInt32(d.integer(forKey: DefaultsKey.inputMode))
+            voiceState.inputMode = VoiceCatInputMode(rawValue: raw) ?? .voiceActivation
+        }
+        if d.object(forKey: DefaultsKey.vadThreshold) != nil {
+            voiceState.vadThreshold = d.float(forKey: DefaultsKey.vadThreshold)
+        }
+        if d.object(forKey: DefaultsKey.inputGain) != nil {
+            voiceState.inputGain = d.float(forKey: DefaultsKey.inputGain)
+        }
+        client.setInputMode(voiceState.inputMode)
+        client.setVadThreshold(voiceState.vadThreshold)
+        client.setInputGain(voiceState.inputGain)
     }
 
     private var pttEngaged = false

clients/apple/iOS/VoiceCatiOS/Views/ChatView.swift

@@ -91,7 +91,7 @@ struct ChatView: View {
     private func sendMessage() {
         let text = composeText.trimmingCharacters(in: .whitespacesAndNewlines)
         guard !text.isEmpty else { return }
-        session.sendText(text, scope: .channel)
+        session.sendText(text, scope: .channel, targetId: session.currentChannelId)
         composeText = ""
     }
 }

clients/apple/iOS/VoiceCatiOS/Views/SettingsView.swift

@@ -237,6 +237,20 @@ struct SettingsView: View {
                             .accessibilityLabel("Voice activation threshold")
                         }
                     }
+
+                    VStack(alignment: .leading, spacing: 4) {
+                        Text("Mic Volume: \(Int((session.voiceState.inputGain * 100).rounded()))%")
+                            .font(.caption)
+                        Slider(
+                            value: Binding(
+                                get: { Double(session.voiceState.inputGain) },
+                                set: { session.setInputGain(Float($0)) }
+                            ),
+                            in: 0...3, step: 0.05
+                        )
+                        .accessibilityLabel("Microphone volume")
+                        .accessibilityValue("\(Int((session.voiceState.inputGain * 100).rounded())) percent")
+                    }
                 }
 
                 // MARK: - Notifications

clients/apple/iOS/VoiceCatiOS/Views/UserRow.swift

@@ -18,6 +18,10 @@ struct UserRow: View {
     var body: some View {
         UserRowView(user: user, isSelf: user.id == session.selfUserId)
             .contextMenu { contextMenu }
+            // The context menu is long-press only, which VoiceOver doesn't surface — mirror the
+            // same buttons as accessibility actions so VoiceOver users can reach per-user tuning
+            // (and the admin actions) via the actions rotor on the focused row.
+            .accessibilityActions { contextMenu }
             .sheet(item: $activeSheet) { sheet in
                 switch sheet {
                 case .tuning:      PerUserTuningView(user: user, session: session)

clients/apple/macOS/VoiceCatMac/Windows/MainWindowController.swift

@@ -33,7 +33,9 @@ final class MainWindowController: NSWindowController, NSWindowDelegate {
     private var screenCapture: ScreenAudioCapture?
     // Last app/exclusion choice from the share picker; reused as the default next time.
     private var screenAudioSelection: ScreenAudioSelection = .default
-    internal var pttKeyCode: UInt16 = 0x60  // F8
+    internal var pttKeyCode: UInt16 = 0x60 {  // F8
+        didSet { UserDefaults.standard.set(Int(pttKeyCode), forKey: AudioDefaults.pttKeyCode) }
+    }
     private var pttMonitor: Any?
     private var pttEngaged = false  // guards the PTT cue against key-repeat
     private var serverMuted = false
@@ -49,9 +51,26 @@ final class MainWindowController: NSWindowController, NSWindowDelegate {
     private var settingsWindowController: SettingsWindowController?
 
     // MARK: - Audio settings state (source of truth — read/written by SettingsWindowController)
+    // The input mode / VAD threshold / mic gain / PTT key persist via UserDefaults (didSet below)
+    // so they survive relaunch; loadPersistedAudioSettings() restores them at startup and they are
+    // pushed into the core when the mic stream starts (micToggleClicked).
 
-    internal var selectedInputMode: VoiceCatInputMode = .voiceActivation
-    internal var vadThresholdValue: Float = 0.05
+    enum AudioDefaults {
+        static let inputMode    = "voice.inputMode"
+        static let vadThreshold = "voice.vadThreshold"
+        static let inputGain    = "voice.inputGain"
+        static let pttKeyCode   = "voice.pttKeyCode"
+    }
+
+    internal var selectedInputMode: VoiceCatInputMode = .voiceActivation {
+        didSet { UserDefaults.standard.set(Int(selectedInputMode.rawValue), forKey: AudioDefaults.inputMode) }
+    }
+    internal var vadThresholdValue: Float = 0.05 {
+        didSet { UserDefaults.standard.set(vadThresholdValue, forKey: AudioDefaults.vadThreshold) }
+    }
+    internal var inputGain: Float = 1.0 {
+        didSet { UserDefaults.standard.set(inputGain, forKey: AudioDefaults.inputGain) }
+    }
     internal var selectedInputDeviceId: String?
 
     // MARK: - UI components
@@ -97,12 +116,32 @@ final class MainWindowController: NSWindowController, NSWindowDelegate {
         super.init(window: window)
         window.delegate = self
 
+        loadPersistedAudioSettings()
         buildUI()
         buildToolbar()
         wireEvents()
         bootstrap()
     }
 
+    /// Restore the saved input mode / VAD threshold / mic gain / PTT key from UserDefaults so a
+    /// relaunch keeps the user's transmission settings instead of resetting to VAD defaults.
+    private func loadPersistedAudioSettings() {
+        let d = UserDefaults.standard
+        if d.object(forKey: AudioDefaults.inputMode) != nil {
+            let raw = UInt32(d.integer(forKey: AudioDefaults.inputMode))
+            selectedInputMode = VoiceCatInputMode(rawValue: raw) ?? .voiceActivation
+        }
+        if d.object(forKey: AudioDefaults.vadThreshold) != nil {
+            vadThresholdValue = d.float(forKey: AudioDefaults.vadThreshold)
+        }
+        if d.object(forKey: AudioDefaults.inputGain) != nil {
+            inputGain = d.float(forKey: AudioDefaults.inputGain)
+        }
+        if d.object(forKey: AudioDefaults.pttKeyCode) != nil {
+            pttKeyCode = UInt16(d.integer(forKey: AudioDefaults.pttKeyCode))
+        }
+    }
+
     required init?(coder: NSCoder) { fatalError() }
 
     deinit {
@@ -712,6 +751,7 @@ final class MainWindowController: NSWindowController, NSWindowDelegate {
                 if selectedInputMode == .voiceActivation {
                     client.setVadThreshold(vadThresholdValue)
                 }
+                client.setInputGain(inputGain)
                 setVoiceJoinedState(true)
                 addActivity("Joined voice — microphone active")
                 EventFeedback.shared.play(.voiceOn)

clients/apple/macOS/VoiceCatMac/Windows/SettingsWindowController.swift

@@ -50,6 +50,14 @@ final class SettingsWindowController: NSWindowController, NSWindowDelegate {
     // Cached VAD slider position so we can restore it when the window reopens.
     private var vadSliderValue: Double = 50
 
+    // Mic input gain: 0–300 % (100 = unity). Persisted via MainWindowController.inputGain.
+    private let inputGainSlider: NSSlider = {
+        let s = NSSlider(value: 100, minValue: 0, maxValue: 300, target: nil, action: nil)
+        s.numberOfTickMarks = 0
+        return s
+    }()
+    private let inputGainValueLabel = NSTextField(labelWithString: "100%")
+
     // Notification feedback controls. Read/write UserDefaults with the same keys VoiceCatCore's
     // FeedbackSettings reads, so EventFeedback honours these immediately.
     private let soundsCheckbox = NSButton(checkboxWithTitle: "Event sounds", target: nil, action: nil)
@@ -135,6 +143,14 @@ final class SettingsWindowController: NSWindowController, NSWindowDelegate {
         levelMeter.setAccessibilityLabel("Microphone input level")
         levelMeter.setAccessibilityHelp("Shows current microphone volume level")
 
+        let inputGainLabel = NSTextField(labelWithString: "Mic volume:")
+        inputGainLabel.setAccessibilityLabel("Microphone volume")
+        inputGainSlider.target = self
+        inputGainSlider.action = #selector(inputGainChanged)
+        inputGainSlider.setAccessibilityLabel("Microphone volume")
+        inputGainSlider.setAccessibilityHelp("Boost a quiet microphone. 100% is unity.")
+        inputGainValueLabel.setAccessibilityLabel("Microphone volume value")
+
         let inputModeRow = NSStackView(views: [inputModeLabel, inputModeControl])
         inputModeRow.orientation = .horizontal
         inputModeRow.spacing = 8
@@ -155,6 +171,10 @@ final class SettingsWindowController: NSWindowController, NSWindowDelegate {
         levelRow.orientation = .horizontal
         levelRow.spacing = 8
 
+        let inputGainRow = NSStackView(views: [inputGainLabel, inputGainSlider, inputGainValueLabel])
+        inputGainRow.orientation = .horizontal
+        inputGainRow.spacing = 8
+
         // Notifications
         let notificationsHeader = NSTextField(labelWithString: "Notifications")
         notificationsHeader.font = .boldSystemFont(ofSize: NSFont.systemFontSize)
@@ -177,8 +197,8 @@ final class SettingsWindowController: NSWindowController, NSWindowDelegate {
         volumeRow.orientation = .horizontal
         volumeRow.spacing = 8
 
-        let stack = NSStackView(views: [inputModeRow, vadRow, pttRow, deviceRow, levelRow,
-                                        notificationsHeader, soundsCheckbox, volumeRow,
+        let stack = NSStackView(views: [inputModeRow, vadRow, inputGainRow, pttRow, deviceRow,
+                                        levelRow, notificationsHeader, soundsCheckbox, volumeRow,
                                         speechCheckbox, selfTalkCheckbox, pttSoundCheckbox])
         stack.orientation = .vertical
         stack.spacing = 12
@@ -194,6 +214,7 @@ final class SettingsWindowController: NSWindowController, NSWindowDelegate {
             stack.bottomAnchor.constraint(equalTo: contentView.bottomAnchor),
 
             vadSlider.widthAnchor.constraint(greaterThanOrEqualToConstant: 200),
+            inputGainSlider.widthAnchor.constraint(greaterThanOrEqualToConstant: 180),
             levelMeter.widthAnchor.constraint(equalToConstant: 200),
             devicePicker.widthAnchor.constraint(greaterThanOrEqualToConstant: 180),
             soundsVolumeSlider.widthAnchor.constraint(greaterThanOrEqualToConstant: 200),
@@ -235,9 +256,15 @@ final class SettingsWindowController: NSWindowController, NSWindowDelegate {
         case .alwaysOn:        inputModeControl.selectedSegment = 2
         }
 
+        // Restore the slider from the persisted threshold (invert vadThresholdFromSlider) so a
+        // relaunch shows the saved sensitivity, not the default mid-point.
+        vadSliderValue = vadSliderFromThreshold(mc.vadThresholdValue)
         vadSlider.doubleValue = vadSliderValue
         pttKeyLabel.stringValue = "(\(keyCodeName(mc.pttKeyCode)))"
 
+        inputGainSlider.doubleValue = Double(mc.inputGain * 100)
+        updateInputGainLabel()
+
         updateConditionalControls()
     }
 
@@ -275,6 +302,21 @@ final class SettingsWindowController: NSWindowController, NSWindowDelegate {
         }
     }
 
+    @objc private func inputGainChanged() {
+        let gain = Float(inputGainSlider.doubleValue) / 100.0
+        mainController?.inputGain = gain
+        updateInputGainLabel()
+        if let mc = mainController, mc.micStreamId != 0 {
+            client.setInputGain(gain)
+        }
+    }
+
+    private func updateInputGainLabel() {
+        let pct = Int(inputGainSlider.doubleValue.rounded())
+        inputGainValueLabel.stringValue = "\(pct)%"
+        inputGainSlider.setAccessibilityValue("\(pct) percent")
+    }
+
     @objc private func changePttClicked() {
         guard let mc = mainController else { return }
         let sheet = PttKeyCaptureSheet(currentKeyCode: mc.pttKeyCode)
@@ -346,6 +388,12 @@ final class SettingsWindowController: NSWindowController, NSWindowDelegate {
         0.1 * (1.0 - Float(vadSlider.doubleValue - 1.0) / 99.0)
     }
 
+    /// Inverse of vadThresholdFromSlider: map a stored threshold back to a 1…100 slider position.
+    private func vadSliderFromThreshold(_ threshold: Float) -> Double {
+        let clamped = min(max(threshold, 0.0), 0.1)
+        return Double(1.0 + (1.0 - clamped / 0.1) * 99.0)
+    }
+
     private func presentSheet(_ vc: NSViewController) {
         if let cvc = window?.contentViewController {
             cvc.presentAsSheet(vc)

clients/windows/VoiceCat.App/Forms/MainForm.Designer.cs

@@ -51,6 +51,8 @@ partial class MainForm
     private ProgressBar pbLevel = null!;
     private Label lblVadThreshold = null!;
     private TrackBar trkVadThreshold = null!;
+    private Label lblMicGain = null!;
+    private TrackBar trkMicGain = null!;
 
     protected override void Dispose(bool disposing)
     {
@@ -94,6 +96,8 @@ partial class MainForm
         pbLevel = new ProgressBar();
         lblVadThreshold = new Label();
         trkVadThreshold = new TrackBar();
+        lblMicGain = new Label();
+        trkMicGain = new TrackBar();
         menuStrip = new MenuStrip();
         toolStrip = new ToolStrip();
         tsbJoinVoice = new ToolStripButton();
@@ -336,6 +340,23 @@ partial class MainForm
         trkVadThreshold.TabIndex = 9;
         trkVadThreshold.Visible = true;
 
+        lblMicGain.Text = "Mic volume:";
+        lblMicGain.AutoSize = true;
+        lblMicGain.Margin = new Padding(12, 5, 4, 0);
+
+        trkMicGain.AccessibleName = "Microphone volume";
+        trkMicGain.AccessibleDescription =
+            "Boost a quiet microphone. 100 is unity; range 0–300 percent.";
+        trkMicGain.Minimum = 0;
+        trkMicGain.Maximum = 300;
+        trkMicGain.Value = 100;
+        trkMicGain.TickFrequency = 25;
+        trkMicGain.SmallChange = 5;
+        trkMicGain.LargeChange = 25;
+        trkMicGain.Width = 120;
+        trkMicGain.Margin = new Padding(0, 2, 0, 0);
+        trkMicGain.TabIndex = 10;
+
         flpVoiceBottom.Dock = DockStyle.Fill;
         flpVoiceBottom.Padding = new Padding(4, 0, 4, 2);
         flpVoiceBottom.Controls.Add(lblInputDevice);
@@ -345,6 +366,8 @@ partial class MainForm
         flpVoiceBottom.Controls.Add(pbLevel);
         flpVoiceBottom.Controls.Add(lblVadThreshold);
         flpVoiceBottom.Controls.Add(trkVadThreshold);
+        flpVoiceBottom.Controls.Add(lblMicGain);
+        flpVoiceBottom.Controls.Add(trkMicGain);
 
         pnlVoice.Dock = DockStyle.Bottom;
         pnlVoice.Height = 68;

clients/windows/VoiceCat.App/Forms/MainForm.cs

@@ -1,4 +1,5 @@
 using VoiceCat.App.Audio;
+using VoiceCat.App.Models;
 using VoiceCat.App.Notifications;
 using VoiceCat.Interop;
 
@@ -14,6 +15,7 @@ public partial class MainForm : Form
     private readonly string _nickname;
     private readonly System.Windows.Forms.Timer _pumpTimer = new() { Interval = 30 };
     private readonly EventFeedback _feedback = new(FeedbackSettings.Load());
+    private readonly VoiceSettings _voiceSettings = VoiceSettings.Load();
 
     // Channel / user state
     private uint _currentChannelId;
@@ -85,6 +87,7 @@ public partial class MainForm : Form
         radioPtt.CheckedChanged += RadioPtt_CheckedChanged;
         radioAlwaysOn.CheckedChanged += RadioAlwaysOn_CheckedChanged;
         trkVadThreshold.Scroll += TrkVadThreshold_Scroll;
+        trkMicGain.Scroll += TrkMicGain_Scroll;
         btnChangePtt.Click += BtnChangePtt_Click;
         btnRefreshDevices.Click += (_, _) => LoadInputDevices();
         cboInputDevice.SelectedIndexChanged += CboInputDevice_SelectedIndexChanged;
@@ -98,9 +101,33 @@ public partial class MainForm : Form
             if (_micStreamId != 0) _client.SetPushToTalk(false);
         };
 
+        ApplyPersistedVoiceSettings();
         BootstrapFromServer();
     }
 
+    /// <summary>
+    /// Restore the saved transmission mode / VAD sensitivity / mic gain / PTT key into the UI so a
+    /// relaunch keeps the user's input settings instead of resetting to the designer defaults. The
+    /// values are pushed into the core when the mic stream starts (<see cref="BtnMicToggle_Click"/>).
+    /// Setting the radio fires CheckedChanged, which only adjusts visibility while the mic is idle.
+    /// </summary>
+    private void ApplyPersistedVoiceSettings()
+    {
+        _pttKey = (Keys)_voiceSettings.PttKey;
+
+        trkVadThreshold.Value = Math.Clamp(_voiceSettings.VadThresholdSlider,
+                                           trkVadThreshold.Minimum, trkVadThreshold.Maximum);
+        trkMicGain.Value = Math.Clamp(_voiceSettings.MicGain,
+                                      trkMicGain.Minimum, trkMicGain.Maximum);
+
+        switch ((VcInputMode)_voiceSettings.InputMode)
+        {
+            case VcInputMode.PushToTalk: radioPtt.Checked = true; break;
+            case VcInputMode.AlwaysOn:   radioAlwaysOn.Checked = true; break;
+            default:                     radioVad.Checked = true; break;
+        }
+    }
+
     // ── Startup ──────────────────────────────────────────────────────────────
 
     private void BootstrapFromServer()
@@ -661,6 +688,7 @@ public partial class MainForm : Form
                     _client.SetInputDevice(streamId, dev.Id);
                 _client.SetInputMode(CurrentInputMode());
                 if (radioVad.Checked) _client.SetVadThreshold(VadThresholdFromSlider());
+                _client.SetInputGain(trkMicGain.Value / 100f);
                 SetVoiceJoinedState(true);
                 AddActivity("Joined voice — microphone active");
                 _feedback.PlaySound(SoundEvent.VoiceOn);
@@ -779,6 +807,7 @@ public partial class MainForm : Form
         btnChangePtt.Visible = false;
         lblVadThreshold.Visible = true;
         trkVadThreshold.Visible = true;
+        SaveInputMode(VcInputMode.VoiceActivation);
         if (_micStreamId != 0)
         {
             _client.SetInputMode(VcInputMode.VoiceActivation);
@@ -794,6 +823,7 @@ public partial class MainForm : Form
         btnChangePtt.Visible = true;
         lblVadThreshold.Visible = false;
         trkVadThreshold.Visible = false;
+        SaveInputMode(VcInputMode.PushToTalk);
         if (_micStreamId != 0)
         {
             _client.SetInputMode(VcInputMode.PushToTalk);
@@ -808,15 +838,31 @@ public partial class MainForm : Form
         btnChangePtt.Visible = false;
         lblVadThreshold.Visible = false;
         trkVadThreshold.Visible = false;
+        SaveInputMode(VcInputMode.AlwaysOn);
         if (_micStreamId != 0) _client.SetInputMode(VcInputMode.AlwaysOn);
     }
 
     private void TrkVadThreshold_Scroll(object? sender, EventArgs e)
     {
+        _voiceSettings.VadThresholdSlider = trkVadThreshold.Value;
+        _voiceSettings.Save();
         if (_micStreamId != 0 && radioVad.Checked)
             _client.SetVadThreshold(VadThresholdFromSlider());
     }
 
+    private void TrkMicGain_Scroll(object? sender, EventArgs e)
+    {
+        _voiceSettings.MicGain = trkMicGain.Value;
+        _voiceSettings.Save();
+        if (_micStreamId != 0) _client.SetInputGain(trkMicGain.Value / 100f);
+    }
+
+    private void SaveInputMode(VcInputMode mode)
+    {
+        _voiceSettings.InputMode = (int)mode;
+        _voiceSettings.Save();
+    }
+
     private float VadThresholdFromSlider() =>
         0.1f * (1f - (trkVadThreshold.Value - 1f) / 99f);
 
@@ -832,6 +878,8 @@ public partial class MainForm : Form
         {
             _pttKey = dlg.CapturedKey;
             lblPttKey.Text = $"({_pttKey})";
+            _voiceSettings.PttKey = (int)_pttKey;
+            _voiceSettings.Save();
         }
     }
 

clients/windows/VoiceCat.App/Models/VoiceSettings.cs

@@ -0,0 +1,53 @@
+using System.Text.Json;
+
+namespace VoiceCat.App.Models;
+
+/// <summary>
+/// User's send-side voice input preferences — transmission mode, VAD sensitivity, mic input
+/// gain, and the push-to-talk key. Persisted to %AppData%\VoiceCat\voice.json, same pattern as
+/// <see cref="ServerListStore"/> and FeedbackSettings: a missing or corrupt file yields defaults
+/// rather than throwing. Slider-position values are stored as-is so MainForm can restore the
+/// TrackBars directly.
+/// </summary>
+public sealed class VoiceSettings
+{
+    /// <summary>Transmission mode: 0 = voice activation, 1 = push-to-talk, 2 = always on
+    /// (matches Interop's VcInputMode).</summary>
+    public int InputMode { get; set; } = 0;
+
+    /// <summary>VAD sensitivity slider position, 1–100 (default mirrors the designer's 76).</summary>
+    public int VadThresholdSlider { get; set; } = 76;
+
+    /// <summary>Microphone input gain slider position, 0–300 percent (100 = unity).</summary>
+    public int MicGain { get; set; } = 100;
+
+    /// <summary>Push-to-talk key, stored as the integer value of System.Windows.Forms.Keys.</summary>
+    public int PttKey { get; set; } = (int)Keys.F8;
+
+    private static readonly JsonSerializerOptions JsonOptions = new() { WriteIndented = true };
+
+    private static string AppDataDir => Path.Combine(
+        Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "VoiceCat");
+
+    private static string FilePath => Path.Combine(AppDataDir, "voice.json");
+
+    public static VoiceSettings Load()
+    {
+        try
+        {
+            if (!File.Exists(FilePath)) return new VoiceSettings();
+            string json = File.ReadAllText(FilePath);
+            return JsonSerializer.Deserialize<VoiceSettings>(json) ?? new VoiceSettings();
+        }
+        catch
+        {
+            return new VoiceSettings();
+        }
+    }
+
+    public void Save()
+    {
+        Directory.CreateDirectory(AppDataDir);
+        File.WriteAllText(FilePath, JsonSerializer.Serialize(this, JsonOptions));
+    }
+}

clients/windows/VoiceCat.Interop/NativeMethods.cs

@@ -80,6 +80,9 @@ internal static partial class NativeMethods
     [LibraryImport(LibName)]
     internal static partial VcResult vc_set_output_volume(nint c, float gain);
 
+    [LibraryImport(LibName)]
+    internal static partial VcResult vc_set_input_gain(nint c, float gain);
+
     [LibraryImport(LibName)]
     internal static partial VcResult vc_set_remote_stream(nint c, uint userId, uint streamId,
         float gain, int muted, int noiseReduction);

clients/windows/VoiceCat.Interop/VoiceCatClient.cs

@@ -227,6 +227,11 @@ public sealed class VoiceCatClient : IDisposable
     public VcResult SetOutputVolume(float gain) =>
         NativeMethods.vc_set_output_volume(_handle.DangerousGetHandle(), gain < 0f ? 0f : gain);
 
+    /// <summary>Send-side microphone input gain, applied to captured MIC PCM before VAD/encode.
+    /// 0.0 = silent, 1.0 = unity (default), &gt;1.0 amplifies (clamped to int16). LOCAL only.</summary>
+    public VcResult SetInputGain(float gain) =>
+        NativeMethods.vc_set_input_gain(_handle.DangerousGetHandle(), gain < 0f ? 0f : gain);
+
     public VcResult SetRemoteStream(uint userId, uint streamId, float gain, bool muted, bool noiseReduction) =>
         NativeMethods.vc_set_remote_stream(_handle.DangerousGetHandle(), userId, streamId, gain,
             muted ? 1 : 0, noiseReduction ? 1 : 0);