feat: add plugin configuration API

src/SharpFM.Plugin.Sample/ClipInspectorPanel.axaml

@@ -19,12 +19,12 @@
                 <TextBlock Classes="Fluent2Body" Text="{Binding ClipType}" />
             </StackPanel>
 
-            <StackPanel Spacing="2">
+            <StackPanel Spacing="2" IsVisible="{Binding ShowElementCount}">
                 <TextBlock Classes="Fluent2Caption" Opacity="0.7" Text="XML Elements" />
                 <TextBlock Classes="Fluent2Body" Text="{Binding ElementCount}" />
             </StackPanel>
 
-            <StackPanel Spacing="2">
+            <StackPanel Spacing="2" IsVisible="{Binding ShowXmlSize}">
                 <TextBlock Classes="Fluent2Caption" Opacity="0.7" Text="Approx. Size" />
                 <TextBlock Classes="Fluent2Body" Text="{Binding XmlSize}" />
             </StackPanel>

src/SharpFM.Plugin.Sample/ClipInspectorPlugin.cs

@@ -17,8 +17,37 @@ public class ClipInspectorPlugin : IPanelPlugin
     public IReadOnlyList<PluginKeyBinding> KeyBindings => [];
     public IReadOnlyList<PluginMenuAction> MenuActions => [];
 
+    public PluginConfigSchema ConfigSchema { get; } = new(new[]
+    {
+        new PluginConfigField(
+            Key: "ShowElementCount",
+            Label: "Show XML element count",
+            Type: PluginConfigFieldType.Bool,
+            DefaultValue: true,
+            Description: "Display the number of XML elements in the selected clip."),
+        new PluginConfigField(
+            Key: "ShowXmlSize",
+            Label: "Show approximate size",
+            Type: PluginConfigFieldType.Bool,
+            DefaultValue: true,
+            Description: "Display the approximate byte size of the clip's XML."),
+    });
+
+    public void OnConfigChanged(IReadOnlyDictionary<string, object?> values)
+    {
+        _showElementCount = values.TryGetValue("ShowElementCount", out var a) && a is bool ba ? ba : true;
+        _showXmlSize = values.TryGetValue("ShowXmlSize", out var b) && b is bool bb ? bb : true;
+        if (_viewModel is not null)
+        {
+            _viewModel.ShowElementCount = _showElementCount;
+            _viewModel.ShowXmlSize = _showXmlSize;
+        }
+    }
+
     private IPluginHost? _host;
     private ClipInspectorViewModel? _viewModel;
+    private bool _showElementCount = true;
+    private bool _showXmlSize = true;
 
     public void Initialize(IPluginHost host)
     {
@@ -29,7 +58,11 @@ public void Initialize(IPluginHost host)
 
     public Control CreatePanel()
     {
-        _viewModel = new ClipInspectorViewModel();
+        _viewModel = new ClipInspectorViewModel
+        {
+            ShowElementCount = _showElementCount,
+            ShowXmlSize = _showXmlSize,
+        };
         _viewModel.Update(_host?.SelectedClip);
         return new ClipInspectorPanel { DataContext = _viewModel };
     }

src/SharpFM.Plugin.Sample/ClipInspectorViewModel.cs

@@ -30,6 +30,12 @@ private void Notify([CallerMemberName] string name = "")
     private bool _hasClip;
     public bool HasClip { get => _hasClip; private set { _hasClip = value; Notify(); } }
 
+    private bool _showElementCount = true;
+    public bool ShowElementCount { get => _showElementCount; set { _showElementCount = value; Notify(); } }
+
+    private bool _showXmlSize = true;
+    public bool ShowXmlSize { get => _showXmlSize; set { _showXmlSize = value; Notify(); } }
+
     public void Update(ClipData? clip)
     {
         if (clip is null)

src/SharpFM.Plugin.XmlViewer/XmlViewerPlugin.cs

@@ -22,6 +22,8 @@ public class XmlViewerPlugin : IPanelPlugin
         [new PluginKeyBinding("Ctrl+Shift+X", "Toggle XML Viewer", () => { })];
 
     public IReadOnlyList<PluginMenuAction> MenuActions => [];
+    public PluginConfigSchema ConfigSchema => PluginConfigSchema.Empty;
+    public void OnConfigChanged(IReadOnlyDictionary<string, object?> values) { }
 
     public void Initialize(IPluginHost host)
     {

src/SharpFM.Plugin/IPlugin.cs

@@ -46,4 +46,20 @@ public interface IPlugin : IDisposable
     /// as a submenu with "Toggle Panel" plus these custom actions.
     /// </summary>
     IReadOnlyList<PluginMenuAction> MenuActions { get; }
+
+    /// <summary>
+    /// Schema for user-tunable configuration values. The host persists these on the
+    /// plugin's behalf and renders a generic settings UI from the schema. Return
+    /// <see cref="PluginConfigSchema.Empty"/> if the plugin has no configuration.
+    /// </summary>
+    PluginConfigSchema ConfigSchema { get; }
+
+    /// <summary>
+    /// Called by the host with the current values for fields declared in
+    /// <see cref="ConfigSchema"/>: once after <see cref="Initialize"/> with the
+    /// persisted (or default) values, and again whenever the user saves edits in the
+    /// Plugin Manager. Keys match <see cref="PluginConfigField.Key"/>; values are
+    /// coerced to the CLR type implied by <see cref="PluginConfigField.Type"/>.
+    /// </summary>
+    void OnConfigChanged(IReadOnlyDictionary<string, object?> values);
 }

src/SharpFM.Plugin/PluginConfigSchema.cs

@@ -0,0 +1,48 @@
+using System;
+using System.Collections.Generic;
+
+namespace SharpFM.Plugin;
+
+/// <summary>
+/// Supported field types for a plugin configuration schema. The host renders a
+/// different control per type and coerces persisted values to the matching CLR type.
+/// </summary>
+public enum PluginConfigFieldType
+{
+    String,
+    MultilineString,
+    Bool,
+    Int,
+    Double,
+    Enum
+}
+
+/// <summary>
+/// A single configurable value declared by a plugin.
+/// </summary>
+/// <param name="Key">Dictionary key used when values are passed back to the plugin.</param>
+/// <param name="Label">Human-readable label shown in the settings UI.</param>
+/// <param name="Type">Field type — determines the rendered control and value coercion.</param>
+/// <param name="DefaultValue">
+/// Value returned when the field has never been set or the persisted value is invalid.
+/// Must be assignable to the CLR type implied by <paramref name="Type"/>.
+/// </param>
+/// <param name="Description">Optional caption shown beneath the control.</param>
+/// <param name="EnumValues">Allowed values when <paramref name="Type"/> is <see cref="PluginConfigFieldType.Enum"/>.</param>
+public sealed record PluginConfigField(
+    string Key,
+    string Label,
+    PluginConfigFieldType Type,
+    object? DefaultValue = null,
+    string? Description = null,
+    IReadOnlyList<string>? EnumValues = null);
+
+/// <summary>
+/// Describes a plugin's user-tunable configuration. The host uses this to
+/// persist values, generate a settings UI, and push the current values into the plugin.
+/// </summary>
+public sealed record PluginConfigSchema(IReadOnlyList<PluginConfigField> Fields)
+{
+    /// <summary>Schema for plugins with no configuration.</summary>
+    public static PluginConfigSchema Empty { get; } = new(Array.Empty<PluginConfigField>());
+}

src/SharpFM/App.axaml.cs

@@ -49,7 +49,8 @@ public override void OnFrameworkInitializationCompleted()
             // Load plugins
             var pluginHost = new PluginHost(viewModel, loggerFactory);
             var pluginUIHost = new PluginUIHost(pluginHost);
-            var pluginService = new PluginService(logger);
+            var pluginConfigService = new PluginConfigService(logger);
+            var pluginService = new PluginService(logger, pluginConfigService);
             pluginService.LoadPlugins(pluginUIHost);
 
             viewModel.AllPlugins = pluginService.AllPlugins;
@@ -62,7 +63,7 @@ public override void OnFrameworkInitializationCompleted()
 
             // Give the window access to plugin services for the manager dialog
             if (desktop.MainWindow is MainWindow mainWindow)
-                mainWindow.SetPluginServices(pluginService, pluginUIHost);
+                mainWindow.SetPluginServices(pluginService, pluginUIHost, pluginConfigService);
 
             desktop.MainWindow.DataContext = viewModel;
 

src/SharpFM/MainWindow.axaml.cs

@@ -26,6 +26,7 @@ public partial class MainWindow : Window
     private TextMate.Installation? _scriptTextMateInstallation;
     private PluginService? _pluginService;
     private PluginUIHost? _pluginHost;
+    private PluginConfigService? _pluginConfigService;
 
     public MainWindow()
     {
@@ -58,10 +59,11 @@ public MainWindow()
         DataContextChanged += OnDataContextChanged;
     }
 
-    public void SetPluginServices(PluginService pluginService, PluginUIHost pluginHost)
+    public void SetPluginServices(PluginService pluginService, PluginUIHost pluginHost, PluginConfigService pluginConfigService)
     {
         _pluginService = pluginService;
         _pluginHost = pluginHost;
+        _pluginConfigService = pluginConfigService;
     }
 
     private void OnDataContextChanged(object? sender, EventArgs e)
@@ -229,11 +231,11 @@ private void UpdatePluginPanelContent()
 
     private void ShowPluginManager()
     {
-        if (_pluginService is null || _pluginHost is null) return;
+        if (_pluginService is null || _pluginHost is null || _pluginConfigService is null) return;
         if (DataContext is not MainWindowViewModel vm) return;
 
         var window = new PluginManagerWindow();
-        window.Configure(_pluginService, _pluginHost, vm);
+        window.Configure(_pluginService, _pluginHost, vm, _pluginConfigService);
         window.ShowDialog(this);
     }
 

src/SharpFM/PluginManager/PluginConfigDialog.axaml

@@ -0,0 +1,33 @@
+<Window
+    xmlns="https://github.com/avaloniaui"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    x:Class="SharpFM.PluginManager.PluginConfigDialog"
+    Width="500"
+    Height="520"
+    CanResize="True"
+    WindowStartupLocation="CenterOwner">
+
+    <Grid Margin="16" RowDefinitions="Auto,*,Auto">
+        <TextBlock
+            Grid.Row="0"
+            x:Name="headerText"
+            Classes="Fluent2Subtitle"
+            Margin="0,0,0,12" />
+
+        <Border Grid.Row="1" Classes="Fluent2SurfaceElevated">
+            <ScrollViewer Padding="12">
+                <StackPanel x:Name="fieldsPanel" Spacing="12" />
+            </ScrollViewer>
+        </Border>
+
+        <StackPanel
+            Grid.Row="2"
+            Orientation="Horizontal"
+            HorizontalAlignment="Right"
+            Spacing="8"
+            Margin="0,12,0,0">
+            <Button x:Name="cancelButton" Classes="Fluent2" Content="Cancel" />
+            <Button x:Name="okButton" Classes="Fluent2Primary" Content="OK" />
+        </StackPanel>
+    </Grid>
+</Window>