From abea874db8b93efe415f9b6b037b78b903e22fd7 Mon Sep 17 00:00:00 2001
From: Robert McRackan <rmcrackan@metabolon.com>
Date: Sat, 25 Jul 2026 21:32:42 -0400
Subject: [PATCH] Add Important settings UI for encrypted token storage

---
 .../Controls/Settings/Important.axaml         |  41 +++-
 .../Dialogs/SettingsDialog.axaml.cs           |  12 +
 .../Settings/ImportantSettingsVM.cs           |  99 +++++++++
 .../Configuration.PersistentSettings.cs       |   2 +-
 .../LibationUiBase/TokenStorageSettingsUi.cs  | 210 ++++++++++++++++++
 .../Dialogs/SettingsDialog.Designer.cs        |  85 ++++++-
 .../Dialogs/SettingsDialog.Important.cs       |  75 ++++++-
 .../Dialogs/SettingsDialog.cs                 |   5 +-
 .../TokenStorageSettingsUiTests.cs            |  56 +++++
 9 files changed, 569 insertions(+), 16 deletions(-)
 create mode 100644 Source/LibationUiBase/TokenStorageSettingsUi.cs
 create mode 100644 Source/_Tests/LibationUiBase.Tests/TokenStorageSettingsUiTests.cs

diff --git a/Source/LibationAvalonia/Controls/Settings/Important.axaml b/Source/LibationAvalonia/Controls/Settings/Important.axaml
index 809aa5c6..4a968693 100644
--- a/Source/LibationAvalonia/Controls/Settings/Important.axaml
+++ b/Source/LibationAvalonia/Controls/Settings/Important.axaml
@@ -8,7 +8,7 @@
 			 x:DataType="vm:ImportantSettingsVM"
              x:Class="LibationAvalonia.Controls.Settings.Important">
 
-	<Grid RowDefinitions="Auto,Auto,Auto,Auto,*">
+	<Grid RowDefinitions="Auto,Auto,Auto,Auto,Auto,*">
 		<controls:GroupBox
 			Grid.Row="0"
 			Margin="5"
@@ -85,8 +85,41 @@
 			</StackPanel>
 		</CheckBox>
 
+		<controls:GroupBox
+			Grid.Row="2"
+			Margin="5"
+			Label="Authentication tokens">
+			<StackPanel>
+				<CheckBox
+					IsEnabled="{Binding CanEditEncryptTokens}"
+					IsChecked="{Binding EncryptTokens, Mode=TwoWay}">
+					<TextBlock Text="{Binding EncryptTokensText}" TextWrapping="Wrap" />
+				</CheckBox>
+				<TextBlock
+					Margin="24,4,0,0"
+					Foreground="DarkRed"
+					IsVisible="{Binding PlaintextWarningVisible}"
+					Text="{Binding PlaintextWarningText}"
+					TextWrapping="Wrap" />
+				<TextBlock
+					Margin="24,4,0,0"
+					Foreground="DarkRed"
+					IsVisible="{Binding OsStoreUnavailableVisible}"
+					Text="{Binding OsStoreUnavailableMessage}"
+					TextWrapping="Wrap" />
+				<Button
+					Margin="0,10,0,0"
+					HorizontalAlignment="Right"
+					Padding="20,0"
+					Content="{Binding ConvertButtonText}"
+					ToolTip.Tip="{Binding ConvertButtonToolTip}"
+					IsEnabled="{Binding ConvertButtonEnabled}"
+					Command="{Binding ConvertExistingTokensCommand}" />
+			</StackPanel>
+		</controls:GroupBox>
+
 		<StackPanel
-			Grid.Row="2" Margin="5"
+			Grid.Row="3" Margin="5"
 			Orientation="Horizontal">
 
 			<TextBlock
@@ -111,7 +144,7 @@
 		</StackPanel>
 
 		<controls:GroupBox
-			Grid.Row="3"
+			Grid.Row="4"
 			Margin="5"
 			Label="Display Settings">
 			<Grid
@@ -166,7 +199,7 @@
 		</controls:GroupBox>
 
 		<Grid
-			Grid.Row="4"
+			Grid.Row="5"
 			ColumnDefinitions="Auto,Auto,*"
 			Margin="10"
 			VerticalAlignment="Bottom">
diff --git a/Source/LibationAvalonia/Dialogs/SettingsDialog.axaml.cs b/Source/LibationAvalonia/Dialogs/SettingsDialog.axaml.cs
index 5fae97a2..de76205b 100644
--- a/Source/LibationAvalonia/Dialogs/SettingsDialog.axaml.cs
+++ b/Source/LibationAvalonia/Dialogs/SettingsDialog.axaml.cs
@@ -2,6 +2,7 @@ using Avalonia.Controls;
 using FileManager;
 using LibationAvalonia.ViewModels.Settings;
 using LibationFileManager;
+using LibationUiBase;
 using LibationUiBase.Forms;
 using System;
 using System.Threading.Tasks;
@@ -32,8 +33,19 @@ public partial class SettingsDialog : DialogWindow
 
 		#endregion
 
+		var tokenDecision = await settingsDisp.ImportantSettings.PromptOnSaveAsync(this);
+		if (tokenDecision == TokenStorageSaveDecision.Abort)
+			return;
+
 		settingsDisp.SaveSettings(config);
 
+		if (tokenDecision == TokenStorageSaveDecision.SavePreferenceAndConvert)
+		{
+			var converted = await settingsDisp.ImportantSettings.ConvertAfterSaveAsync(this);
+			if (!converted)
+				return;
+		}
+
 		await MessageBox.VerboseLoggingWarning_ShowIfTrue();
 		await base.SaveAndCloseAsync();
 	}
diff --git a/Source/LibationAvalonia/ViewModels/Settings/ImportantSettingsVM.cs b/Source/LibationAvalonia/ViewModels/Settings/ImportantSettingsVM.cs
index 07b1d380..bd8c8300 100644
--- a/Source/LibationAvalonia/ViewModels/Settings/ImportantSettingsVM.cs
+++ b/Source/LibationAvalonia/ViewModels/Settings/ImportantSettingsVM.cs
@@ -1,3 +1,5 @@
+using AudibleApi.Authorization;
+using AudibleUtilities;
 using Dinah.Core;
 using FileManager;
 using LibationFileManager;
@@ -6,6 +8,8 @@ using ReactiveUI;
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Threading.Tasks;
+using System.Windows.Input;
 
 namespace LibationAvalonia.ViewModels.Settings;
 
@@ -13,6 +17,13 @@ public class ImportantSettingsVM : ViewModelBase
 {
 	private EnumDisplay<Configuration.Theme> themeVariant;
 	private readonly Configuration config;
+	private bool encryptTokens;
+	private bool plaintextWarningVisible;
+	private bool convertButtonEnabled;
+	private bool osStoreUnavailableVisible;
+	private string osStoreUnavailableMessage = "";
+	private TokenStorageMethod initialTokenStorageMethod;
+	private bool osSecretStoreAvailable;
 
 	public ImportantSettingsVM(Configuration config)
 	{
@@ -29,8 +40,33 @@ public class ImportantSettingsVM : ViewModelBase
 		GridFontScaleFactor = scaleFactorToLinearRange(config.GridFontScaleFactor);
 
 		themeVariant = Themes.Single(v => v.Value == config.ThemeVariant);
+
+		initialTokenStorageMethod = config.TokenStorageMethod;
+		osSecretStoreAvailable = IdentityTokenStorageWiring.IsOsSecretStoreAvailable(out var unavailableReason);
+		if (!osSecretStoreAvailable)
+		{
+			OsStoreUnavailableVisible = true;
+			OsStoreUnavailableMessage = TokenStorageSettingsUi.OsStoreUnavailableMessage(unavailableReason);
+			encryptTokens = false;
+			CanEditEncryptTokens = false;
+		}
+		else
+		{
+			OsStoreUnavailableVisible = false;
+			encryptTokens = TokenStorageSettingsUi.CheckboxFromMethod(config.TokenStorageMethod);
+			CanEditEncryptTokens = true;
+		}
+
+		RefreshTokenStorageUiState();
+		ConvertExistingTokensCommand = ReactiveCommand.CreateFromTask(ConvertExistingTokensAsync);
 	}
 
+	public async Task<TokenStorageSaveDecision> PromptOnSaveAsync(object? owner)
+		=> await TokenStorageSettingsUi.PromptOnPreferenceSaveAsync(owner, initialTokenStorageMethod, SelectedTokenStorageMethod);
+
+	public async Task<bool> ConvertAfterSaveAsync(object? owner)
+		=> await TokenStorageSettingsUi.RunConversionAsync(owner, SelectedTokenStorageMethod);
+
 	public void SaveSettings(Configuration config)
 	{
 		config.Books = GetBooksDirectory();
@@ -40,6 +76,9 @@ public class ImportantSettingsVM : ViewModelBase
 		config.LastWriteTime = LastWriteTime.Value;
 		config.UseWebView = UseWebView;
 		config.LogLevel = LoggingLevel;
+		config.TokenStorageMethod = SelectedTokenStorageMethod;
+		initialTokenStorageMethod = SelectedTokenStorageMethod;
+		RefreshTokenStorageUiState();
 	}
 
 	public LongPath GetBooksDirectory()
@@ -63,6 +102,24 @@ public class ImportantSettingsVM : ViewModelBase
 			Go.To.Folder(Configuration.Instance.LibationFiles.Location.ShortPathName);
 	}
 
+	private async Task ConvertExistingTokensAsync()
+	{
+		var converted = await TokenStorageSettingsUi.ConfirmAndConvertAsync(null, SelectedTokenStorageMethod);
+		if (converted)
+			RefreshTokenStorageUiState();
+	}
+
+	private void RefreshTokenStorageUiState()
+	{
+		var method = SelectedTokenStorageMethod;
+		PlaintextWarningVisible = osSecretStoreAvailable && method == TokenStorageMethod.Plaintext;
+		var alignment = AccountTokenStorage.GetAccountsAlignment(method);
+		ConvertButtonEnabled = TokenStorageSettingsUi.IsConvertButtonEnabled(alignment);
+	}
+
+	private TokenStorageMethod SelectedTokenStorageMethod
+		=> TokenStorageSettingsUi.MethodFromCheckbox(EncryptTokens);
+
 	public List<Configuration.KnownDirectories> KnownDirectories { get; } = new()
 	{
 		Configuration.KnownDirectories.LibationFiles,
@@ -95,6 +152,12 @@ public class ImportantSettingsVM : ViewModelBase
 		.Select(v => new EnumDisplay<Configuration.Theme>(v))
 		.ToArray();
 
+	public string EncryptTokensText { get; } = TokenStorageSettingsUi.CheckboxText;
+	public string PlaintextWarningText { get; } = TokenStorageSettingsUi.PlaintextWarningText;
+	public string ConvertButtonText { get; } = TokenStorageSettingsUi.ConvertButtonText;
+	public string ConvertButtonToolTip { get; } = TokenStorageSettingsUi.ConvertButtonToolTip;
+	public bool CanEditEncryptTokens { get; }
+
 	public string BooksDirectory { get; set; }
 	public bool SavePodcastsToParentFolder { get; set; }
 	public bool OverwriteExisting { get; set; }
@@ -105,6 +168,42 @@ public class ImportantSettingsVM : ViewModelBase
 	public bool UseWebView { get; set; }
 	public Serilog.Events.LogEventLevel LoggingLevel { get; set; }
 
+	public bool EncryptTokens
+	{
+		get => encryptTokens;
+		set
+		{
+			this.RaiseAndSetIfChanged(ref encryptTokens, value);
+			RefreshTokenStorageUiState();
+		}
+	}
+
+	public bool PlaintextWarningVisible
+	{
+		get => plaintextWarningVisible;
+		private set => this.RaiseAndSetIfChanged(ref plaintextWarningVisible, value);
+	}
+
+	public bool ConvertButtonEnabled
+	{
+		get => convertButtonEnabled;
+		private set => this.RaiseAndSetIfChanged(ref convertButtonEnabled, value);
+	}
+
+	public bool OsStoreUnavailableVisible
+	{
+		get => osStoreUnavailableVisible;
+		private set => this.RaiseAndSetIfChanged(ref osStoreUnavailableVisible, value);
+	}
+
+	public string OsStoreUnavailableMessage
+	{
+		get => osStoreUnavailableMessage;
+		private set => this.RaiseAndSetIfChanged(ref osStoreUnavailableMessage, value);
+	}
+
+	public ICommand ConvertExistingTokensCommand { get; }
+
 	public EnumDisplay<Configuration.Theme> ThemeVariant
 	{
 		get => themeVariant;
diff --git a/Source/LibationFileManager/Configuration.PersistentSettings.cs b/Source/LibationFileManager/Configuration.PersistentSettings.cs
index 1e995260..a88538d6 100644
--- a/Source/LibationFileManager/Configuration.PersistentSettings.cs
+++ b/Source/LibationFileManager/Configuration.PersistentSettings.cs
@@ -302,7 +302,7 @@ public partial class Configuration
 		AC_4
 	}
 
-	[Description("Store authentication tokens encrypted using the OS secret store.\r\nUnchecking stores tokens in plaintext in AccountsSettings.json.\r\nChanging this setting does not convert existing tokens until you choose to convert them.")]
+	[Description("Store authentication tokens encrypted. Unchecking this option stores tokens in plaintext.")]
 	public TokenStorageMethod TokenStorageMethod
 	{
 		get => GetNonString(defaultValue: TokenStorageMethod.Encrypted);
diff --git a/Source/LibationUiBase/TokenStorageSettingsUi.cs b/Source/LibationUiBase/TokenStorageSettingsUi.cs
new file mode 100644
index 00000000..ee127a28
--- /dev/null
+++ b/Source/LibationUiBase/TokenStorageSettingsUi.cs
@@ -0,0 +1,210 @@
+using AudibleApi.Authorization;
+using AudibleUtilities;
+using LibationUiBase.Forms;
+using System.Threading.Tasks;
+
+namespace LibationUiBase;
+
+/// <summary>
+/// Shared copy and workflows for Important settings token-storage controls.
+/// </summary>
+public static class TokenStorageSettingsUi
+{
+	public const string CheckboxText
+		= "Store authentication tokens encrypted. Unchecking this option stores tokens in plaintext.";
+
+	public const string PlaintextWarningText
+		= "Authentication tokens will be stored as readable plaintext in AccountsSettings.json.";
+
+	public const string ConvertButtonText = "Update existing stored tokens";
+
+	public const string ConvertButtonToolTip
+		= "Convert existing tokens in AccountsSettings.json to match the currently selected storage method.";
+
+	public const string SavePromptCaption = "Convert existing tokens?";
+	public const string ConvertConfirmCaption = "Confirm token conversion";
+	public const string ConversionFailedCaption = "Token conversion failed";
+	public const string ConversionSucceededCaption = "Tokens updated";
+	public const string OsStoreUnavailableCaption = "Encrypted token storage unavailable";
+
+	public const string SavePromptEncrypted
+		= "New and refreshed authentication tokens will now be stored encrypted. Would you also like to encrypt and re-save existing plaintext tokens?";
+
+	public const string SavePromptPlaintext
+		= "New and refreshed authentication tokens will now be stored in plaintext. Would you also like to decrypt and re-save existing encrypted tokens? This will make those token values readable in the account settings file.";
+
+	public const string StandaloneConfirmEncrypted
+		= "Encrypt and re-save existing plaintext authentication tokens so they match the current setting?";
+
+	public const string StandaloneConfirmPlaintext
+		= "Decrypt and re-save existing encrypted authentication tokens as plaintext? This will make those token values readable in the account settings file.";
+
+	public const string ConversionSucceededMessage
+		= "Existing authentication tokens were updated to match the selected storage method.";
+
+	public static TokenStorageMethod MethodFromCheckbox(bool storeEncrypted)
+		=> storeEncrypted ? TokenStorageMethod.Encrypted : TokenStorageMethod.Plaintext;
+
+	public static bool CheckboxFromMethod(TokenStorageMethod method)
+		=> method == TokenStorageMethod.Encrypted;
+
+	/// <summary>
+	/// Convert is offered for mismatches and indeterminate state.
+	/// Matching / no-token states keep the button disabled.
+	/// </summary>
+	public static bool IsConvertButtonEnabled(TokenStorageAlignment alignment)
+		=> alignment is TokenStorageAlignment.SomeMismatch or TokenStorageAlignment.Indeterminate;
+
+	public static string SavePromptBody(TokenStorageMethod method)
+		=> method == TokenStorageMethod.Encrypted ? SavePromptEncrypted : SavePromptPlaintext;
+
+	public static string StandaloneConfirmBody(TokenStorageMethod method)
+		=> method == TokenStorageMethod.Encrypted ? StandaloneConfirmEncrypted : StandaloneConfirmPlaintext;
+
+	public static string OsStoreUnavailableMessage(string? unavailableReason)
+		=> string.IsNullOrWhiteSpace(unavailableReason)
+			? "Encrypted token storage requires an OS secret store, which is not available. Tokens cannot be stored encrypted."
+			: $"Encrypted token storage requires an OS secret store, which is not available: {unavailableReason}";
+
+	public static string FormatConversionError(IdentityTokenConversionResult result)
+	{
+		var error = string.IsNullOrWhiteSpace(result.Error)
+			? "Token conversion failed."
+			: result.Error!;
+
+		if (result.FailedCategories.Count == 0)
+			return error;
+
+		return $"{error}\r\n\r\nFailed categories: {string.Join(", ", result.FailedCategories)}";
+	}
+
+	/// <summary>
+	/// Decide whether saving a changed preference should also convert existing tokens.
+	/// Cancel / dismiss must never be treated as approval.
+	/// </summary>
+	public static async Task<TokenStorageSaveDecision> PromptOnPreferenceSaveAsync(
+		object? owner,
+		TokenStorageMethod originalMethod,
+		TokenStorageMethod selectedMethod)
+	{
+		if (originalMethod == selectedMethod)
+			return TokenStorageSaveDecision.SavePreferenceOnly;
+
+		if (selectedMethod == TokenStorageMethod.Encrypted
+			&& !IdentityTokenStorageWiring.IsOsSecretStoreAvailable(out var unavailableReason))
+		{
+			await MessageBoxBase.Show(
+				owner,
+				OsStoreUnavailableMessage(unavailableReason),
+				OsStoreUnavailableCaption,
+				MessageBoxButtons.OK,
+				MessageBoxIcon.Error);
+			return TokenStorageSaveDecision.Abort;
+		}
+
+		var alignment = AccountTokenStorage.GetAccountsAlignment(selectedMethod);
+		if (alignment is TokenStorageAlignment.AllMatch or TokenStorageAlignment.NoApplicableTokens)
+			return TokenStorageSaveDecision.SavePreferenceOnly;
+
+		var result = await MessageBoxBase.Show(
+			owner,
+			SavePromptBody(selectedMethod),
+			SavePromptCaption,
+			MessageBoxButtons.YesNoCancel,
+			MessageBoxIcon.Warning,
+			defaultButton: selectedMethod == TokenStorageMethod.Plaintext
+				? MessageBoxDefaultButton.Button2
+				: MessageBoxDefaultButton.Button1);
+
+		return result switch
+		{
+			DialogResult.Yes => TokenStorageSaveDecision.SavePreferenceAndConvert,
+			DialogResult.No => TokenStorageSaveDecision.SavePreferenceOnly,
+			_ => TokenStorageSaveDecision.Abort
+		};
+	}
+
+	public static async Task<bool> ConfirmAndConvertAsync(object? owner, TokenStorageMethod method)
+	{
+		if (method == TokenStorageMethod.Encrypted
+			&& !IdentityTokenStorageWiring.IsOsSecretStoreAvailable(out var unavailableReason))
+		{
+			await MessageBoxBase.Show(
+				owner,
+				OsStoreUnavailableMessage(unavailableReason),
+				OsStoreUnavailableCaption,
+				MessageBoxButtons.OK,
+				MessageBoxIcon.Error);
+			return false;
+		}
+
+		var alignment = AccountTokenStorage.GetAccountsAlignment(method);
+		if (!IsConvertButtonEnabled(alignment))
+			return false;
+
+		var confirm = await MessageBoxBase.Show(
+			owner,
+			StandaloneConfirmBody(method),
+			ConvertConfirmCaption,
+			MessageBoxButtons.YesNo,
+			MessageBoxIcon.Warning,
+			defaultButton: method == TokenStorageMethod.Plaintext
+				? MessageBoxDefaultButton.Button2
+				: MessageBoxDefaultButton.Button1);
+
+		if (confirm != DialogResult.Yes)
+			return false;
+
+		return await RunConversionAsync(owner, method);
+	}
+
+	public static async Task<bool> RunConversionAsync(object? owner, TokenStorageMethod method)
+	{
+		IdentityTokenConversionResult result;
+		try
+		{
+			result = AccountTokenStorage.ConvertAllAccounts(method);
+		}
+		catch (System.Exception ex)
+		{
+			Serilog.Log.Logger.Warning(ex, "Token conversion failed");
+			await MessageBoxBase.Show(
+				owner,
+				"Token conversion failed. The original AccountsSettings.json file was left unchanged.",
+				ConversionFailedCaption,
+				MessageBoxButtons.OK,
+				MessageBoxIcon.Error);
+			return false;
+		}
+
+		if (!result.Succeeded)
+		{
+			await MessageBoxBase.Show(
+				owner,
+				FormatConversionError(result),
+				ConversionFailedCaption,
+				MessageBoxButtons.OK,
+				MessageBoxIcon.Error);
+			return false;
+		}
+
+		if (result.Changed)
+		{
+			await MessageBoxBase.Show(
+				owner,
+				ConversionSucceededMessage,
+				ConversionSucceededCaption,
+				MessageBoxButtons.OK,
+				MessageBoxIcon.Information);
+		}
+
+		return true;
+	}
+}
+
+public enum TokenStorageSaveDecision
+{
+	Abort,
+	SavePreferenceOnly,
+	SavePreferenceAndConvert
+}
diff --git a/Source/LibationWinForms/Dialogs/SettingsDialog.Designer.cs b/Source/LibationWinForms/Dialogs/SettingsDialog.Designer.cs
index f2a6ed4d..36d9d262 100644
--- a/Source/LibationWinForms/Dialogs/SettingsDialog.Designer.cs
+++ b/Source/LibationWinForms/Dialogs/SettingsDialog.Designer.cs
@@ -58,6 +58,11 @@
 			gridScaleFactorTbar = new System.Windows.Forms.TrackBar();
 			gridFontScaleFactorLbl = new System.Windows.Forms.Label();
 			gridFontScaleFactorTbar = new System.Windows.Forms.TrackBar();
+			tokenStorageGb = new System.Windows.Forms.GroupBox();
+			encryptTokensCbox = new System.Windows.Forms.CheckBox();
+			plaintextTokenWarningLbl = new System.Windows.Forms.Label();
+			osSecretStoreUnavailableLbl = new System.Windows.Forms.Label();
+			updateExistingTokensBtn = new System.Windows.Forms.Button();
 			booksGb = new System.Windows.Forms.GroupBox();
 			booksSelectControl = new DirectoryOrCustomSelectControl();
 			lastWriteTimeCb = new System.Windows.Forms.ComboBox();
@@ -148,6 +153,7 @@
 			groupBox1.SuspendLayout();
 			((System.ComponentModel.ISupportInitialize)gridScaleFactorTbar).BeginInit();
 			((System.ComponentModel.ISupportInitialize)gridFontScaleFactorTbar).BeginInit();
+			tokenStorageGb.SuspendLayout();
 			booksGb.SuspendLayout();
 			tab2ImportLibrary.SuspendLayout();
 			tab3DownloadDecrypt.SuspendLayout();
@@ -349,7 +355,7 @@
 			// 
 			// logsBtn
 			// 
-			logsBtn.Location = new System.Drawing.Point(256, 424);
+			logsBtn.Location = new System.Drawing.Point(256, 534);
 			logsBtn.Name = "logsBtn";
 			logsBtn.Size = new System.Drawing.Size(132, 23);
 			logsBtn.TabIndex = 5;
@@ -360,7 +366,7 @@
 			// loggingLevelLbl
 			// 
 			loggingLevelLbl.AutoSize = true;
-			loggingLevelLbl.Location = new System.Drawing.Point(6, 427);
+			loggingLevelLbl.Location = new System.Drawing.Point(6, 537);
 			loggingLevelLbl.Name = "loggingLevelLbl";
 			loggingLevelLbl.Size = new System.Drawing.Size(78, 15);
 			loggingLevelLbl.TabIndex = 3;
@@ -370,7 +376,7 @@
 			// 
 			loggingLevelCb.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList;
 			loggingLevelCb.FormattingEnabled = true;
-			loggingLevelCb.Location = new System.Drawing.Point(90, 424);
+			loggingLevelCb.Location = new System.Drawing.Point(90, 534);
 			loggingLevelCb.Name = "loggingLevelCb";
 			loggingLevelCb.Size = new System.Drawing.Size(129, 23);
 			loggingLevelCb.TabIndex = 4;
@@ -396,6 +402,7 @@
 			tab1ImportantSettings.Controls.Add(themeCb);
 			tab1ImportantSettings.Controls.Add(label22);
 			tab1ImportantSettings.Controls.Add(groupBox1);
+			tab1ImportantSettings.Controls.Add(tokenStorageGb);
 			tab1ImportantSettings.Controls.Add(booksGb);
 			tab1ImportantSettings.Controls.Add(logsBtn);
 			tab1ImportantSettings.Controls.Add(loggingLevelCb);
@@ -410,7 +417,7 @@
 			// themeLbl
 			// 
 			themeLbl.AutoSize = true;
-			themeLbl.Location = new System.Drawing.Point(190, 393);
+			themeLbl.Location = new System.Drawing.Point(190, 503);
 			themeLbl.Name = "themeLbl";
 			themeLbl.Size = new System.Drawing.Size(296, 15);
 			themeLbl.TabIndex = 12;
@@ -420,7 +427,7 @@
 			// 
 			themeCb.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList;
 			themeCb.FormattingEnabled = true;
-			themeCb.Location = new System.Drawing.Point(63, 390);
+			themeCb.Location = new System.Drawing.Point(63, 500);
 			themeCb.Name = "themeCb";
 			themeCb.Size = new System.Drawing.Size(121, 23);
 			themeCb.TabIndex = 11;
@@ -429,7 +436,7 @@
 			// label22
 			// 
 			label22.AutoSize = true;
-			label22.Location = new System.Drawing.Point(4, 393);
+			label22.Location = new System.Drawing.Point(4, 503);
 			label22.Name = "label22";
 			label22.Size = new System.Drawing.Size(44, 15);
 			label22.TabIndex = 10;
@@ -443,7 +450,7 @@
 			groupBox1.Controls.Add(gridScaleFactorTbar);
 			groupBox1.Controls.Add(gridFontScaleFactorLbl);
 			groupBox1.Controls.Add(gridFontScaleFactorTbar);
-			groupBox1.Location = new System.Drawing.Point(6, 277);
+			groupBox1.Location = new System.Drawing.Point(6, 387);
 			groupBox1.Name = "groupBox1";
 			groupBox1.Size = new System.Drawing.Size(844, 83);
 			groupBox1.TabIndex = 9;
@@ -503,6 +510,63 @@
 			gridFontScaleFactorTbar.TabIndex = 7;
 			gridFontScaleFactorTbar.TickFrequency = 25;
 			// 
+			// tokenStorageGb
+			// 
+			tokenStorageGb.Anchor = System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Left | System.Windows.Forms.AnchorStyles.Right;
+			tokenStorageGb.Controls.Add(updateExistingTokensBtn);
+			tokenStorageGb.Controls.Add(osSecretStoreUnavailableLbl);
+			tokenStorageGb.Controls.Add(plaintextTokenWarningLbl);
+			tokenStorageGb.Controls.Add(encryptTokensCbox);
+			tokenStorageGb.Location = new System.Drawing.Point(6, 277);
+			tokenStorageGb.Name = "tokenStorageGb";
+			tokenStorageGb.Size = new System.Drawing.Size(844, 104);
+			tokenStorageGb.TabIndex = 8;
+			tokenStorageGb.TabStop = false;
+			tokenStorageGb.Text = "Authentication tokens";
+			// 
+			// encryptTokensCbox
+			// 
+			encryptTokensCbox.AutoSize = true;
+			encryptTokensCbox.Location = new System.Drawing.Point(8, 22);
+			encryptTokensCbox.Name = "encryptTokensCbox";
+			encryptTokensCbox.Size = new System.Drawing.Size(520, 19);
+			encryptTokensCbox.TabIndex = 0;
+			encryptTokensCbox.Text = "Store authentication tokens encrypted. Unchecking this option stores tokens in plaintext.";
+			encryptTokensCbox.UseVisualStyleBackColor = true;
+			encryptTokensCbox.CheckedChanged += encryptTokensCbox_CheckedChanged;
+			// 
+			// plaintextTokenWarningLbl
+			// 
+			plaintextTokenWarningLbl.AutoSize = true;
+			plaintextTokenWarningLbl.ForeColor = System.Drawing.Color.DarkRed;
+			plaintextTokenWarningLbl.Location = new System.Drawing.Point(27, 44);
+			plaintextTokenWarningLbl.Name = "plaintextTokenWarningLbl";
+			plaintextTokenWarningLbl.Size = new System.Drawing.Size(480, 15);
+			plaintextTokenWarningLbl.TabIndex = 1;
+			plaintextTokenWarningLbl.Text = "Authentication tokens will be stored as readable plaintext in AccountsSettings.json.";
+			// 
+			// osSecretStoreUnavailableLbl
+			// 
+			osSecretStoreUnavailableLbl.AutoSize = true;
+			osSecretStoreUnavailableLbl.ForeColor = System.Drawing.Color.DarkRed;
+			osSecretStoreUnavailableLbl.Location = new System.Drawing.Point(27, 44);
+			osSecretStoreUnavailableLbl.Name = "osSecretStoreUnavailableLbl";
+			osSecretStoreUnavailableLbl.Size = new System.Drawing.Size(250, 15);
+			osSecretStoreUnavailableLbl.TabIndex = 2;
+			osSecretStoreUnavailableLbl.Text = "[OS secret store unavailable]";
+			osSecretStoreUnavailableLbl.Visible = false;
+			// 
+			// updateExistingTokensBtn
+			// 
+			updateExistingTokensBtn.Anchor = System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Right;
+			updateExistingTokensBtn.Location = new System.Drawing.Point(628, 68);
+			updateExistingTokensBtn.Name = "updateExistingTokensBtn";
+			updateExistingTokensBtn.Size = new System.Drawing.Size(200, 27);
+			updateExistingTokensBtn.TabIndex = 3;
+			updateExistingTokensBtn.Text = "Update existing stored tokens";
+			updateExistingTokensBtn.UseVisualStyleBackColor = true;
+			updateExistingTokensBtn.Click += updateExistingTokensBtn_Click;
+			// 
 			// booksGb
 			// 
 			booksGb.Anchor = System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Left | System.Windows.Forms.AnchorStyles.Right;
@@ -1493,6 +1557,8 @@
 			groupBox1.PerformLayout();
 			((System.ComponentModel.ISupportInitialize)gridScaleFactorTbar).EndInit();
 			((System.ComponentModel.ISupportInitialize)gridFontScaleFactorTbar).EndInit();
+			tokenStorageGb.ResumeLayout(false);
+			tokenStorageGb.PerformLayout();
 			booksGb.ResumeLayout(false);
 			booksGb.PerformLayout();
 			tab2ImportLibrary.ResumeLayout(false);
@@ -1544,6 +1610,11 @@
 		private System.Windows.Forms.CheckBox splitFilesByChapterCbox;
 		public System.Windows.Forms.TabControl tabControl;
 		private System.Windows.Forms.TabPage tab1ImportantSettings;
+		private System.Windows.Forms.GroupBox tokenStorageGb;
+		private System.Windows.Forms.CheckBox encryptTokensCbox;
+		private System.Windows.Forms.Label plaintextTokenWarningLbl;
+		private System.Windows.Forms.Label osSecretStoreUnavailableLbl;
+		private System.Windows.Forms.Button updateExistingTokensBtn;
 		private System.Windows.Forms.GroupBox booksGb;
 		private System.Windows.Forms.TabPage tab2ImportLibrary;
 		private System.Windows.Forms.TabPage tab3DownloadDecrypt;
diff --git a/Source/LibationWinForms/Dialogs/SettingsDialog.Important.cs b/Source/LibationWinForms/Dialogs/SettingsDialog.Important.cs
index 24c023b7..6b7bf9db 100644
--- a/Source/LibationWinForms/Dialogs/SettingsDialog.Important.cs
+++ b/Source/LibationWinForms/Dialogs/SettingsDialog.Important.cs
@@ -1,10 +1,13 @@
-using Dinah.Core;
+using AudibleApi.Authorization;
+using AudibleUtilities;
+using Dinah.Core;
 using FileManager;
 using LibationFileManager;
 using LibationUiBase;
 using System;
 using System.IO;
 using System.Linq;
+using System.Threading.Tasks;
 using System.Windows.Forms;
 
 namespace LibationWinForms.Dialogs;
@@ -20,6 +23,8 @@ public partial class SettingsDialog
 	}
 	private Configuration.Theme themeVariant;
 	private Configuration.Theme initialThemeVariant;
+	private TokenStorageMethod initialTokenStorageMethod;
+	private bool osSecretStoreAvailable;
 
 	private void Load_Important(Configuration config)
 	{
@@ -67,9 +72,60 @@ public partial class SettingsDialog
 		overwriteExistingCbox.Checked = config.OverwriteExisting;
 		gridScaleFactorTbar.Value = scaleFactorToLinearRange(config.GridScaleFactor);
 		gridFontScaleFactorTbar.Value = scaleFactorToLinearRange(config.GridFontScaleFactor);
+
+		Load_TokenStorage(config);
 	}
 
-	private bool Save_Important(Configuration config)
+	private void Load_TokenStorage(Configuration config)
+	{
+		initialTokenStorageMethod = config.TokenStorageMethod;
+		osSecretStoreAvailable = IdentityTokenStorageWiring.IsOsSecretStoreAvailable(out var unavailableReason);
+
+		encryptTokensCbox.Text = TokenStorageSettingsUi.CheckboxText;
+		plaintextTokenWarningLbl.Text = TokenStorageSettingsUi.PlaintextWarningText;
+		updateExistingTokensBtn.Text = TokenStorageSettingsUi.ConvertButtonText;
+		toolTip.SetToolTip(updateExistingTokensBtn, TokenStorageSettingsUi.ConvertButtonToolTip);
+
+		if (!osSecretStoreAvailable)
+		{
+			osSecretStoreUnavailableLbl.Text = TokenStorageSettingsUi.OsStoreUnavailableMessage(unavailableReason);
+			osSecretStoreUnavailableLbl.Visible = true;
+			encryptTokensCbox.Checked = false;
+			encryptTokensCbox.Enabled = false;
+		}
+		else
+		{
+			osSecretStoreUnavailableLbl.Visible = false;
+			encryptTokensCbox.Enabled = true;
+			encryptTokensCbox.Checked = TokenStorageSettingsUi.CheckboxFromMethod(config.TokenStorageMethod);
+		}
+
+		RefreshTokenStorageUiState();
+	}
+
+	private TokenStorageMethod SelectedTokenStorageMethod
+		=> TokenStorageSettingsUi.MethodFromCheckbox(encryptTokensCbox.Checked);
+
+	private void RefreshTokenStorageUiState()
+	{
+		var method = SelectedTokenStorageMethod;
+		plaintextTokenWarningLbl.Visible = osSecretStoreAvailable && method == TokenStorageMethod.Plaintext;
+
+		var alignment = AccountTokenStorage.GetAccountsAlignment(method);
+		updateExistingTokensBtn.Enabled = TokenStorageSettingsUi.IsConvertButtonEnabled(alignment);
+	}
+
+	private void encryptTokensCbox_CheckedChanged(object? sender, EventArgs e)
+		=> RefreshTokenStorageUiState();
+
+	private async void updateExistingTokensBtn_Click(object? sender, EventArgs e)
+	{
+		var converted = await TokenStorageSettingsUi.ConfirmAndConvertAsync(this, SelectedTokenStorageMethod);
+		if (converted)
+			RefreshTokenStorageUiState();
+	}
+
+	private async Task<bool> Save_Important(Configuration config)
 	{
 		var newBooks = booksSelectControl.SelectedDirectory;
 
@@ -96,6 +152,10 @@ public partial class SettingsDialog
 		}
 		#endregion
 
+		var selectedTokenMethod = SelectedTokenStorageMethod;
+		var tokenDecision = await TokenStorageSettingsUi.PromptOnPreferenceSaveAsync(this, initialTokenStorageMethod, selectedTokenMethod);
+		if (tokenDecision == TokenStorageSaveDecision.Abort)
+			return false;
 
 		config.Books = newBooks;
 
@@ -116,6 +176,17 @@ public partial class SettingsDialog
 		config.CreationTime = (creationTimeCb.SelectedItem as EnumDisplay<Configuration.DateTimeSource>)?.Value ?? Configuration.DateTimeSource.File;
 		config.LastWriteTime = (lastWriteTimeCb.SelectedItem as EnumDisplay<Configuration.DateTimeSource>)?.Value ?? Configuration.DateTimeSource.File;
 		config.ThemeVariant = (themeCb.SelectedItem as EnumDisplay<Configuration.Theme>)?.Value ?? Configuration.Theme.System;
+		config.TokenStorageMethod = selectedTokenMethod;
+
+		if (tokenDecision == TokenStorageSaveDecision.SavePreferenceAndConvert)
+		{
+			var converted = await TokenStorageSettingsUi.RunConversionAsync(this, selectedTokenMethod);
+			if (!converted)
+				return false;
+		}
+
+		initialTokenStorageMethod = selectedTokenMethod;
+		RefreshTokenStorageUiState();
 		return true;
 	}
 
diff --git a/Source/LibationWinForms/Dialogs/SettingsDialog.cs b/Source/LibationWinForms/Dialogs/SettingsDialog.cs
index 8e1d762a..f3801e15 100644
--- a/Source/LibationWinForms/Dialogs/SettingsDialog.cs
+++ b/Source/LibationWinForms/Dialogs/SettingsDialog.cs
@@ -1,6 +1,7 @@
 using LibationFileManager;
 using LibationFileManager.Templates;
 using System;
+using System.Threading.Tasks;
 using System.Windows.Forms;
 
 namespace LibationWinForms.Dialogs;
@@ -40,9 +41,9 @@ public partial class SettingsDialog : Form
 			textBox.Text = template.EditingTemplate.TemplateText;
 	}
 
-	private void saveBtn_Click(object sender, EventArgs e)
+	private async void saveBtn_Click(object sender, EventArgs e)
 	{
-		if (!Save_Important(config)) return;
+		if (!await Save_Important(config)) return;
 		Save_ImportLibrary(config);
 		Save_DownloadDecrypt(config);
 		Save_AudioSettings(config);
diff --git a/Source/_Tests/LibationUiBase.Tests/TokenStorageSettingsUiTests.cs b/Source/_Tests/LibationUiBase.Tests/TokenStorageSettingsUiTests.cs
new file mode 100644
index 00000000..663e7b09
--- /dev/null
+++ b/Source/_Tests/LibationUiBase.Tests/TokenStorageSettingsUiTests.cs
@@ -0,0 +1,56 @@
+using AudibleApi.Authorization;
+using LibationUiBase;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace TokenStorageSettingsUiTests;
+
+[TestClass]
+public class TokenStorageSettingsUiTests
+{
+	[TestMethod]
+	public void Checkbox_maps_to_enum_values()
+	{
+		Assert.AreEqual(TokenStorageMethod.Encrypted, TokenStorageSettingsUi.MethodFromCheckbox(true));
+		Assert.AreEqual(TokenStorageMethod.Plaintext, TokenStorageSettingsUi.MethodFromCheckbox(false));
+		Assert.IsTrue(TokenStorageSettingsUi.CheckboxFromMethod(TokenStorageMethod.Encrypted));
+		Assert.IsFalse(TokenStorageSettingsUi.CheckboxFromMethod(TokenStorageMethod.Plaintext));
+	}
+
+	[TestMethod]
+	public void Convert_button_enabled_only_for_mismatch_or_indeterminate()
+	{
+		Assert.IsTrue(TokenStorageSettingsUi.IsConvertButtonEnabled(TokenStorageAlignment.SomeMismatch));
+		Assert.IsTrue(TokenStorageSettingsUi.IsConvertButtonEnabled(TokenStorageAlignment.Indeterminate));
+		Assert.IsFalse(TokenStorageSettingsUi.IsConvertButtonEnabled(TokenStorageAlignment.AllMatch));
+		Assert.IsFalse(TokenStorageSettingsUi.IsConvertButtonEnabled(TokenStorageAlignment.NoApplicableTokens));
+	}
+
+	[TestMethod]
+	public void Prompt_bodies_warn_clearly()
+	{
+		Assert.AreEqual(
+			TokenStorageSettingsUi.SavePromptEncrypted,
+			TokenStorageSettingsUi.SavePromptBody(TokenStorageMethod.Encrypted));
+		Assert.AreEqual(
+			TokenStorageSettingsUi.SavePromptPlaintext,
+			TokenStorageSettingsUi.SavePromptBody(TokenStorageMethod.Plaintext));
+
+		StringAssert.Contains(TokenStorageSettingsUi.SavePromptPlaintext, "readable");
+		StringAssert.Contains(TokenStorageSettingsUi.StandaloneConfirmPlaintext, "readable");
+	}
+
+	[TestMethod]
+	public void FormatConversionError_includes_categories_without_secret_values()
+	{
+		var result = IdentityTokenConversionResult.Failure(
+			TokenStorageAlignment.SomeMismatch,
+			"Conversion failed.",
+			"RefreshToken",
+			"AccessToken");
+
+		var message = TokenStorageSettingsUi.FormatConversionError(result);
+		StringAssert.Contains(message, "RefreshToken");
+		StringAssert.Contains(message, "AccessToken");
+		Assert.IsFalse(message.Contains("Atna|"));
+	}
+}