0.5.19

插件系统V2

LanMountainDesktop.PluginSdk/IPlugin.cs

@@ -1,6 +1,9 @@
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+
 namespace LanMountainDesktop.PluginSdk;
 
 public interface IPlugin
 {
-    void Initialize(IPluginContext context);
+    void Initialize(HostBuilderContext context, IServiceCollection services);
 }

LanMountainDesktop.PluginSdk/IPluginContext.cs

@@ -1,27 +1,6 @@
-using System.Collections.Generic;
-
 namespace LanMountainDesktop.PluginSdk;
 
-public interface IPluginContext
+[Obsolete("Plugin API 2.0.0 uses IPluginRuntimeContext and IServiceCollection-based initialization.")]
+public interface IPluginContext : IPluginRuntimeContext
 {
-    PluginManifest Manifest { get; }
-
-    string PluginDirectory { get; }
-
-    string DataDirectory { get; }
-
-    IServiceProvider Services { get; }
-
-    IReadOnlyDictionary<string, object?> Properties { get; }
-
-    T? GetService<T>();
-
-    bool TryGetProperty<T>(string key, out T? value);
-
-    void RegisterService<TService>(TService service)
-        where TService : class;
-
-    void RegisterSettingsPage(PluginSettingsPageRegistration registration);
-
-    void RegisterDesktopComponent(PluginDesktopComponentRegistration registration);
 }

LanMountainDesktop.PluginSdk/IPluginExportRegistry.cs

@@ -0,0 +1,13 @@
+namespace LanMountainDesktop.PluginSdk;
+
+public interface IPluginExportRegistry
+{
+    IReadOnlyList<PluginServiceExportDescriptor> GetExports();
+
+    IReadOnlyList<PluginServiceExportDescriptor> GetExports(Type contractType);
+
+    PluginServiceExportDescriptor? GetExport(Type contractType, string providerPluginId);
+
+    TContract? GetExport<TContract>(string providerPluginId)
+        where TContract : class;
+}

LanMountainDesktop.PluginSdk/IPluginRuntimeContext.cs

@@ -0,0 +1,18 @@
+namespace LanMountainDesktop.PluginSdk;
+
+public interface IPluginRuntimeContext
+{
+    PluginManifest Manifest { get; }
+
+    string PluginDirectory { get; }
+
+    string DataDirectory { get; }
+
+    IServiceProvider Services { get; }
+
+    IReadOnlyDictionary<string, object?> Properties { get; }
+
+    T? GetService<T>();
+
+    bool TryGetProperty<T>(string key, out T? value);
+}

LanMountainDesktop.PluginSdk/LanMountainDesktop.PluginSdk.csproj

@@ -1,15 +1,17 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <TargetFramework>net10.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
-    <Version>1.0.0</Version>
+    <Version>2.0.0</Version>
   </PropertyGroup>
 
   <ItemGroup>
     <Compile Remove="_build_verify_*\**\*.cs" />
     <PackageReference Include="Avalonia" Version="11.3.12" />
+    <PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="10.0.0" />
+    <PackageReference Include="Microsoft.Extensions.Hosting.Abstractions" Version="10.0.0" />
   </ItemGroup>
 
 </Project>

LanMountainDesktop.PluginSdk/PluginBase.cs

@@ -1,8 +1,11 @@
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+
 namespace LanMountainDesktop.PluginSdk;
 
 public abstract class PluginBase : IPlugin
 {
-    public virtual void Initialize(IPluginContext context)
+    public virtual void Initialize(HostBuilderContext context, IServiceCollection services)
     {
     }
 }

LanMountainDesktop.PluginSdk/PluginDesktopComponentRegistration.cs

@@ -7,7 +7,7 @@ public sealed class PluginDesktopComponentRegistration
     public PluginDesktopComponentRegistration(
         string componentId,
         string displayName,
-        Func<PluginDesktopComponentContext, Control> controlFactory,
+        Func<IServiceProvider, PluginDesktopComponentContext, Control> controlFactory,
         string iconKey = "PuzzlePiece",
         string category = "Plugins",
         int minWidthCells = 2,
@@ -40,13 +40,42 @@ public sealed class PluginDesktopComponentRegistration
         CornerRadiusResolver = cornerRadiusResolver;
     }
 
+    public PluginDesktopComponentRegistration(
+        string componentId,
+        string displayName,
+        Func<PluginDesktopComponentContext, Control> controlFactory,
+        string iconKey = "PuzzlePiece",
+        string category = "Plugins",
+        int minWidthCells = 2,
+        int minHeightCells = 2,
+        bool allowDesktopPlacement = true,
+        bool allowStatusBarPlacement = false,
+        PluginDesktopComponentResizeMode resizeMode = PluginDesktopComponentResizeMode.Proportional,
+        string? displayNameLocalizationKey = null,
+        Func<double, double>? cornerRadiusResolver = null)
+        : this(
+            componentId,
+            displayName,
+            (_, context) => controlFactory(context),
+            iconKey,
+            category,
+            minWidthCells,
+            minHeightCells,
+            allowDesktopPlacement,
+            allowStatusBarPlacement,
+            resizeMode,
+            displayNameLocalizationKey,
+            cornerRadiusResolver)
+    {
+    }
+
     public string ComponentId { get; }
 
     public string DisplayName { get; }
 
     public string? DisplayNameLocalizationKey { get; }
 
-    public Func<PluginDesktopComponentContext, Control> ControlFactory { get; }
+    public Func<IServiceProvider, PluginDesktopComponentContext, Control> ControlFactory { get; }
 
     public string IconKey { get; }
 

LanMountainDesktop.PluginSdk/PluginLocalizer.cs

@@ -26,7 +26,7 @@ public sealed class PluginLocalizer
 
     public string LanguageCode { get; }
 
-    public static PluginLocalizer Create(IPluginContext context)
+    public static PluginLocalizer Create(IPluginRuntimeContext context)
     {
         ArgumentNullException.ThrowIfNull(context);
         return new PluginLocalizer(context.PluginDirectory, ResolveLanguageCode(context.Properties));

LanMountainDesktop.PluginSdk/PluginManifest.cs

@@ -9,7 +9,8 @@ public sealed record PluginManifest(
     string? Description = null,
     string? Author = null,
     string? Version = null,
-    string? ApiVersion = null)
+    string? ApiVersion = null,
+    IReadOnlyList<PluginSharedContractReference>? SharedContracts = null)
 {
     private static readonly JsonSerializerOptions SerializerOptions = new()
     {
@@ -57,6 +58,7 @@ public sealed record PluginManifest(
 
     private PluginManifest NormalizeAndValidate(string manifestPath)
     {
+        var normalizedSharedContracts = NormalizeSharedContracts(manifestPath, SharedContracts);
         var normalized = this with
         {
             Id = RequireValue(Id, nameof(Id), manifestPath),
@@ -65,7 +67,8 @@ public sealed record PluginManifest(
             Description = NormalizeOptionalValue(Description),
             Author = NormalizeOptionalValue(Author),
             Version = NormalizeOptionalValue(Version),
-            ApiVersion = NormalizeOptionalValue(ApiVersion) ?? PluginSdkInfo.ApiVersion
+            ApiVersion = NormalizeOptionalValue(ApiVersion) ?? PluginSdkInfo.ApiVersion,
+            SharedContracts = normalizedSharedContracts
         };
 
         if (!System.Version.TryParse(normalized.ApiVersion, out var requestedVersion))
@@ -82,7 +85,41 @@ public sealed record PluginManifest(
         if (requestedVersion.Major != currentVersion.Major)
         {
             throw new InvalidOperationException(
-                $"Plugin '{normalized.Id}' targets API version '{normalized.ApiVersion}', but the host provides '{PluginSdkInfo.ApiVersion}'.");
+                $"Plugin '{normalized.Id}' targets API version '{normalized.ApiVersion}', but the host provides '{PluginSdkInfo.ApiVersion}'. Upgrade the plugin to API {PluginSdkInfo.ApiVersion}.");
+        }
+
+        return normalized;
+    }
+
+    private static IReadOnlyList<PluginSharedContractReference> NormalizeSharedContracts(
+        string manifestPath,
+        IReadOnlyList<PluginSharedContractReference>? sharedContracts)
+    {
+        if (sharedContracts is null || sharedContracts.Count == 0)
+        {
+            return Array.Empty<PluginSharedContractReference>();
+        }
+
+        var normalized = new List<PluginSharedContractReference>(sharedContracts.Count);
+        var seenIds = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+
+        foreach (var contract in sharedContracts)
+        {
+            if (contract is null)
+            {
+                throw new InvalidOperationException(
+                    $"Plugin manifest '{manifestPath}' contains a null shared contract declaration.");
+            }
+
+            var normalizedContract = contract.NormalizeAndValidate(manifestPath);
+            var contractKey = $"{normalizedContract.Id}@{normalizedContract.Version}";
+            if (!seenIds.Add(contractKey))
+            {
+                throw new InvalidOperationException(
+                    $"Plugin manifest '{manifestPath}' declares duplicate shared contract '{contractKey}'.");
+            }
+
+            normalized.Add(normalizedContract);
         }
 
         return normalized;

LanMountainDesktop.PluginSdk/PluginSdkInfo.cs

@@ -2,7 +2,7 @@ namespace LanMountainDesktop.PluginSdk;
 
 public static class PluginSdkInfo
 {
-    public const string ApiVersion = "1.0.0";
+    public const string ApiVersion = "2.0.0";
     public const string ManifestFileName = "plugin.json";
     public const string PackageFileExtension = ".laapp";
     public const string DataDirectoryName = "Data";

LanMountainDesktop.PluginSdk/PluginServiceCollectionExtensions.cs

@@ -0,0 +1,95 @@
+using Avalonia.Controls;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace LanMountainDesktop.PluginSdk;
+
+public static class PluginServiceCollectionExtensions
+{
+    public static IServiceCollection AddPluginSettingsPage<TControl>(
+        this IServiceCollection services,
+        string id,
+        string title,
+        int sortOrder = 0)
+        where TControl : Control
+    {
+        ArgumentNullException.ThrowIfNull(services);
+
+        services.AddSingleton(new PluginSettingsPageRegistration(
+            id,
+            title,
+            provider => ActivatorUtilities.CreateInstance<TControl>(provider),
+            sortOrder));
+        return services;
+    }
+
+    public static IServiceCollection AddPluginDesktopComponent<TControl>(
+        this IServiceCollection services,
+        string componentId,
+        string displayName,
+        string iconKey = "PuzzlePiece",
+        string category = "Plugins",
+        int minWidthCells = 2,
+        int minHeightCells = 2,
+        bool allowDesktopPlacement = true,
+        bool allowStatusBarPlacement = false,
+        PluginDesktopComponentResizeMode resizeMode = PluginDesktopComponentResizeMode.Proportional,
+        string? displayNameLocalizationKey = null,
+        Func<double, double>? cornerRadiusResolver = null)
+        where TControl : Control
+    {
+        ArgumentNullException.ThrowIfNull(services);
+
+        services.AddSingleton(new PluginDesktopComponentRegistration(
+            componentId,
+            displayName,
+            (provider, context) => ActivatorUtilities.CreateInstance<TControl>(provider, context),
+            iconKey,
+            category,
+            minWidthCells,
+            minHeightCells,
+            allowDesktopPlacement,
+            allowStatusBarPlacement,
+            resizeMode,
+            displayNameLocalizationKey,
+            cornerRadiusResolver));
+        return services;
+    }
+
+    public static IServiceCollection AddPluginExport<TContract, TImplementation>(this IServiceCollection services)
+        where TContract : class
+        where TImplementation : class, TContract
+    {
+        ArgumentNullException.ThrowIfNull(services);
+
+        EnsureSingletonRegistration<TContract, TImplementation>(services);
+
+        if (!services.Any(descriptor =>
+                descriptor.ServiceType == typeof(PluginServiceExportRegistration) &&
+                descriptor.ImplementationInstance is PluginServiceExportRegistration existing &&
+                existing.ContractType == typeof(TContract) &&
+                existing.ImplementationType == typeof(TImplementation)))
+        {
+            services.AddSingleton(new PluginServiceExportRegistration(typeof(TContract), typeof(TImplementation)));
+        }
+
+        return services;
+    }
+
+    private static void EnsureSingletonRegistration<TContract, TImplementation>(IServiceCollection services)
+        where TContract : class
+        where TImplementation : class, TContract
+    {
+        var contractDescriptor = services.LastOrDefault(descriptor => descriptor.ServiceType == typeof(TContract));
+        if (contractDescriptor is null)
+        {
+            services.AddSingleton<TContract, TImplementation>();
+            return;
+        }
+
+        if (contractDescriptor.Lifetime != ServiceLifetime.Singleton)
+        {
+            throw new InvalidOperationException(
+                $"Exported contract '{typeof(TContract).FullName}' must be registered as Singleton.");
+        }
+    }
+}

LanMountainDesktop.PluginSdk/PluginServiceExportDescriptor.cs

@@ -0,0 +1,6 @@
+namespace LanMountainDesktop.PluginSdk;
+
+public sealed record PluginServiceExportDescriptor(
+    string ProviderPluginId,
+    Type ContractType,
+    object ServiceInstance);

LanMountainDesktop.PluginSdk/PluginServiceExportRegistration.cs

@@ -0,0 +1,17 @@
+namespace LanMountainDesktop.PluginSdk;
+
+public sealed class PluginServiceExportRegistration
+{
+    public PluginServiceExportRegistration(Type contractType, Type implementationType)
+    {
+        ArgumentNullException.ThrowIfNull(contractType);
+        ArgumentNullException.ThrowIfNull(implementationType);
+
+        ContractType = contractType;
+        ImplementationType = implementationType;
+    }
+
+    public Type ContractType { get; }
+
+    public Type ImplementationType { get; }
+}

LanMountainDesktop.PluginSdk/PluginSettingsPageRegistration.cs

@@ -7,7 +7,7 @@ public sealed class PluginSettingsPageRegistration
     public PluginSettingsPageRegistration(
         string id,
         string title,
-        Func<Control> contentFactory,
+        Func<IServiceProvider, Control> contentFactory,
         int sortOrder = 0)
     {
         ArgumentException.ThrowIfNullOrWhiteSpace(id);
@@ -20,11 +20,20 @@ public sealed class PluginSettingsPageRegistration
         SortOrder = sortOrder;
     }
 
+    public PluginSettingsPageRegistration(
+        string id,
+        string title,
+        Func<Control> contentFactory,
+        int sortOrder = 0)
+        : this(id, title, _ => contentFactory(), sortOrder)
+    {
+    }
+
     public string Id { get; }
 
     public string Title { get; }
 
     public int SortOrder { get; }
 
-    public Func<Control> ContentFactory { get; }
+    public Func<IServiceProvider, Control> ContentFactory { get; }
 }

LanMountainDesktop.PluginSdk/PluginSharedContractReference.cs

@@ -0,0 +1,47 @@
+using System.Text.Json.Serialization;
+
+namespace LanMountainDesktop.PluginSdk;
+
+public sealed record PluginSharedContractReference(
+    string Id,
+    string Version,
+    string AssemblyName)
+{
+    [JsonIgnore]
+    public string NormalizedId => Id.Trim();
+
+    [JsonIgnore]
+    public string NormalizedVersion => Version.Trim();
+
+    [JsonIgnore]
+    public string NormalizedAssemblyName => AssemblyName.Trim();
+
+    internal PluginSharedContractReference NormalizeAndValidate(string manifestPath)
+    {
+        var normalized = this with
+        {
+            Id = RequireValue(Id, nameof(Id), manifestPath),
+            Version = RequireValue(Version, nameof(Version), manifestPath),
+            AssemblyName = RequireValue(AssemblyName, nameof(AssemblyName), manifestPath)
+        };
+
+        if (!System.Version.TryParse(normalized.Version, out _))
+        {
+            throw new InvalidOperationException(
+                $"Plugin manifest '{manifestPath}' declares invalid shared contract version '{normalized.Version}' for '{normalized.Id}'.");
+        }
+
+        return normalized;
+    }
+
+    private static string RequireValue(string? value, string propertyName, string manifestPath)
+    {
+        if (string.IsNullOrWhiteSpace(value))
+        {
+            throw new InvalidOperationException(
+                $"Plugin manifest '{manifestPath}' is missing required shared contract property '{propertyName}'.");
+        }
+
+        return value.Trim();
+    }
+}

LanMountainDesktop/LanMountainDesktop.csproj

@@ -47,6 +47,8 @@
     <PackageReference Include="FluentIcons.Avalonia" Version="2.0.319" />
     <PackageReference Include="FluentIcons.Avalonia.Fluent" Version="2.0.319" />
     <PackageReference Include="Material.Icons.Avalonia" Version="2.4.1" />
+    <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="10.0.0" />
+    <PackageReference Include="Microsoft.Extensions.Hosting.Abstractions" Version="10.0.0" />
     <PackageReference Include="Microsoft.Data.Sqlite" Version="10.0.0" />
     <PackageReference Include="LibVLCSharp.Avalonia" Version="3.9.5" />
     <PackageReference Include="PortAudioSharp2" Version="1.0.6" />

LanMountainDesktop/Services/DesktopComponentRegistryFactory.cs

@@ -118,13 +118,13 @@ public static class DesktopComponentRegistryFactory
                 contribution.Plugin.Manifest,
                 contribution.Plugin.Context.PluginDirectory,
                 contribution.Plugin.Context.DataDirectory,
-                contribution.Plugin.Context.Services,
+                contribution.Plugin.Services,
                 contribution.Plugin.Context.Properties,
                 contribution.Registration.ComponentId,
                 context.PlacementId,
                 context.CellSize);
 
-            return contribution.Registration.ControlFactory(pluginContext);
+            return contribution.Registration.ControlFactory(contribution.Plugin.Services, pluginContext);
         }
         catch (Exception ex)
         {

LanMountainDesktop/plugins/LoadedPlugin.cs

@@ -5,6 +5,7 @@ using System.Threading;
 using System.Threading.Tasks;
 
 using LanMountainDesktop.PluginSdk;
+using Microsoft.Extensions.Hosting;
 
 namespace LanMountainDesktop.Plugins;
 
@@ -18,9 +19,12 @@ public sealed class LoadedPlugin : IDisposable, IAsyncDisposable
         string assemblyPath,
         Assembly assembly,
         IPlugin plugin,
-        IPluginContext context,
+        IPluginRuntimeContext runtimeContext,
+        IServiceProvider services,
         IReadOnlyList<PluginSettingsPageRegistration> settingsPages,
         IReadOnlyList<PluginDesktopComponentRegistration> desktopComponents,
+        IReadOnlyList<PluginServiceExportDescriptor> exportedServices,
+        IReadOnlyList<IHostedService> hostedServices,
         PluginLoadContext loadContext)
     {
         Manifest = manifest;
@@ -28,9 +32,12 @@ public sealed class LoadedPlugin : IDisposable, IAsyncDisposable
         AssemblyPath = assemblyPath;
         Assembly = assembly;
         Plugin = plugin;
-        Context = context;
+        RuntimeContext = runtimeContext;
+        Services = services;
         SettingsPages = settingsPages;
         DesktopComponents = desktopComponents;
+        ExportedServices = exportedServices;
+        HostedServices = hostedServices;
         LoadContext = loadContext;
     }
 
@@ -44,14 +51,22 @@ public sealed class LoadedPlugin : IDisposable, IAsyncDisposable
 
     public IPlugin Plugin { get; }
 
-    public IPluginContext Context { get; }
+    public IPluginRuntimeContext RuntimeContext { get; }
+
+    public IPluginRuntimeContext Context => RuntimeContext;
+
+    public IServiceProvider Services { get; }
 
     public IReadOnlyList<PluginSettingsPageRegistration> SettingsPages { get; }
 
     public IReadOnlyList<PluginDesktopComponentRegistration> DesktopComponents { get; }
 
+    public IReadOnlyList<PluginServiceExportDescriptor> ExportedServices { get; }
+
     public PluginLoadContext LoadContext { get; }
 
+    private IReadOnlyList<IHostedService> HostedServices { get; }
+
     public void Dispose()
     {
         DisposeAsync().AsTask().GetAwaiter().GetResult();
@@ -64,6 +79,18 @@ public sealed class LoadedPlugin : IDisposable, IAsyncDisposable
             return;
         }
 
+        for (var i = HostedServices.Count - 1; i >= 0; i--)
+        {
+            try
+            {
+                await HostedServices[i].StopAsync(CancellationToken.None);
+            }
+            catch
+            {
+                // Ignore plugin hosted service shutdown failures to allow unload cleanup.
+            }
+        }
+
         if (Plugin is IAsyncDisposable asyncDisposable)
         {
             await asyncDisposable.DisposeAsync();
@@ -73,11 +100,20 @@ public sealed class LoadedPlugin : IDisposable, IAsyncDisposable
             disposable.Dispose();
         }
 
-        if (Context is IAsyncDisposable asyncContext)
+        if (Services is IAsyncDisposable asyncServices)
+        {
+            await asyncServices.DisposeAsync();
+        }
+        else if (Services is IDisposable disposableServices)
+        {
+            disposableServices.Dispose();
+        }
+
+        if (RuntimeContext is IAsyncDisposable asyncContext)
         {
             await asyncContext.DisposeAsync();
         }
-        else if (Context is IDisposable disposableContext)
+        else if (RuntimeContext is IDisposable disposableContext)
         {
             disposableContext.Dispose();
         }

LanMountainDesktop/plugins/MainWindow.PluginSettingsHost.cs

@@ -85,7 +85,7 @@ public partial class MainWindow
         Control content;
         try
         {
-            content = contribution.Registration.ContentFactory();
+            content = contribution.Registration.ContentFactory(contribution.Plugin.Services);
         }
         catch (Exception ex)
         {

LanMountainDesktop/plugins/PluginExportRegistry.cs

@@ -0,0 +1,83 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using LanMountainDesktop.PluginSdk;
+
+namespace LanMountainDesktop.Plugins;
+
+internal sealed class PluginExportRegistry : IPluginExportRegistry
+{
+    private readonly object _gate = new();
+    private readonly List<PluginServiceExportDescriptor> _exports = [];
+
+    public IReadOnlyList<PluginServiceExportDescriptor> GetExports()
+    {
+        lock (_gate)
+        {
+            return _exports.ToArray();
+        }
+    }
+
+    public IReadOnlyList<PluginServiceExportDescriptor> GetExports(Type contractType)
+    {
+        ArgumentNullException.ThrowIfNull(contractType);
+
+        lock (_gate)
+        {
+            return _exports
+                .Where(descriptor => descriptor.ContractType == contractType)
+                .ToArray();
+        }
+    }
+
+    public PluginServiceExportDescriptor? GetExport(Type contractType, string providerPluginId)
+    {
+        ArgumentNullException.ThrowIfNull(contractType);
+        ArgumentException.ThrowIfNullOrWhiteSpace(providerPluginId);
+
+        lock (_gate)
+        {
+            return _exports.FirstOrDefault(descriptor =>
+                descriptor.ContractType == contractType &&
+                string.Equals(descriptor.ProviderPluginId, providerPluginId, StringComparison.OrdinalIgnoreCase));
+        }
+    }
+
+    public TContract? GetExport<TContract>(string providerPluginId)
+        where TContract : class
+    {
+        return GetExport(typeof(TContract), providerPluginId)?.ServiceInstance as TContract;
+    }
+
+    public void ReplaceExports(string pluginId, IEnumerable<PluginServiceExportDescriptor> descriptors)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(pluginId);
+        ArgumentNullException.ThrowIfNull(descriptors);
+
+        lock (_gate)
+        {
+            _exports.RemoveAll(descriptor =>
+                string.Equals(descriptor.ProviderPluginId, pluginId, StringComparison.OrdinalIgnoreCase));
+            _exports.AddRange(descriptors);
+        }
+    }
+
+    public void RemoveExports(string pluginId)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(pluginId);
+
+        lock (_gate)
+        {
+            _exports.RemoveAll(descriptor =>
+                string.Equals(descriptor.ProviderPluginId, pluginId, StringComparison.OrdinalIgnoreCase));
+        }
+    }
+
+    public void Clear()
+    {
+        lock (_gate)
+        {
+            _exports.Clear();
+        }
+    }
+}

LanMountainDesktop/plugins/PluginLoader.cs

@@ -12,6 +12,8 @@ using System.Threading.Tasks;
 
 using LanMountainDesktop.Services;
 using LanMountainDesktop.PluginSdk;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
 
 namespace LanMountainDesktop.Plugins;
 
@@ -135,19 +137,45 @@ public sealed class PluginLoader
     {
         PluginLoadContext? loadContext = null;
         IPlugin? plugin = null;
-        PluginContext? context = null;
+        PluginRuntimeContext? runtimeContext = null;
+        ServiceProvider? pluginServices = null;
+        IReadOnlyList<IHostedService> hostedServices = Array.Empty<IHostedService>();
 
         try
         {
+            Directory.CreateDirectory(dataDirectory);
+            ValidatePluginRuntimeAssets(manifest, assemblyPath, pluginDirectory);
+
             loadContext = new PluginLoadContext(assemblyPath, _options.SharedAssemblyNames);
             var assembly = loadContext.LoadFromAssemblyPath(assemblyPath);
             var pluginType = ResolvePluginType(assembly);
             plugin = CreatePluginInstance(pluginType);
-            context = CreateContext(manifest, pluginDirectory, dataDirectory, services, properties);
+            runtimeContext = CreateRuntimeContext(manifest, pluginDirectory, dataDirectory, properties);
+            var serviceCollection = CreateServiceCollection(runtimeContext, services);
+            var hostBuilderContext = CreateHostBuilderContext(runtimeContext);
 
-            plugin.Initialize(context);
+            plugin.Initialize(hostBuilderContext, serviceCollection);
-            var settingsPages = context.GetSettingsPagesSnapshot();
+
-            var desktopComponents = context.GetDesktopComponentsSnapshot();
+            pluginServices = serviceCollection.BuildServiceProvider(new ServiceProviderOptions
+            {
+                ValidateScopes = false,
+                ValidateOnBuild = true
+            });
+            runtimeContext.SetServices(pluginServices);
+
+            var settingsPages = pluginServices
+                .GetServices<PluginSettingsPageRegistration>()
+                .OrderBy(page => page.SortOrder)
+                .ThenBy(page => page.Title, StringComparer.OrdinalIgnoreCase)
+                .ToArray();
+            var desktopComponents = pluginServices
+                .GetServices<PluginDesktopComponentRegistration>()
+                .OrderBy(component => component.Category, StringComparer.OrdinalIgnoreCase)
+                .ThenBy(component => component.DisplayName, StringComparer.OrdinalIgnoreCase)
+                .ToArray();
+            var exportedServices = ResolveExports(manifest, pluginServices);
+            hostedServices = pluginServices.GetServices<IHostedService>().ToArray();
+            StartHostedServices(hostedServices);
 
             var loadedPlugin = new LoadedPlugin(
                 manifest,
@@ -155,17 +183,22 @@ public sealed class PluginLoader
                 assemblyPath,
                 assembly,
                 plugin,
-                context,
+                runtimeContext,
+                pluginServices,
                 settingsPages,
                 desktopComponents,
+                exportedServices,
+                hostedServices,
                 loadContext);
 
             return PluginLoadResult.Success(sourcePath, manifest, loadedPlugin);
         }
         catch (Exception ex)
         {
+            StopHostedServices(hostedServices);
+            DisposeInstance(pluginServices);
             DisposeInstance(plugin);
-            DisposeInstance(context);
+            DisposeInstance(runtimeContext);
             loadContext?.Unload();
             return PluginLoadResult.Failure(sourcePath, manifest, ex);
         }
@@ -243,23 +276,124 @@ public sealed class PluginLoader
         }
     }
 
-    private PluginContext CreateContext(
+    private PluginRuntimeContext CreateRuntimeContext(
         PluginManifest manifest,
         string pluginDirectory,
         string dataDirectory,
-        IServiceProvider? services,
         IReadOnlyDictionary<string, object?>? properties)
     {
-        Directory.CreateDirectory(dataDirectory);
+        return new PluginRuntimeContext(
-
-        return new PluginContext(
             manifest,
             pluginDirectory,
             dataDirectory,
-            services ?? NullServiceProvider.Instance,
             CreateReadOnlyProperties(properties));
     }
 
+    private ServiceCollection CreateServiceCollection(
+        PluginRuntimeContext runtimeContext,
+        IServiceProvider? hostServices)
+    {
+        var services = new ServiceCollection();
+        services.AddSingleton(runtimeContext);
+        services.AddSingleton<IPluginRuntimeContext>(runtimeContext);
+        services.AddSingleton(runtimeContext.Manifest);
+        services.AddSingleton<IReadOnlyDictionary<string, object?>>(runtimeContext.Properties);
+        services.AddSingleton<IPluginMessageBus, PluginMessageBus>();
+
+        RegisterHostService<IPluginPackageManager>(services, hostServices);
+        RegisterHostService<IHostApplicationLifecycle>(services, hostServices);
+        RegisterHostService<IPluginExportRegistry>(services, hostServices);
+
+        return services;
+    }
+
+    private static void RegisterHostService<TService>(IServiceCollection services, IServiceProvider? hostServices)
+        where TService : class
+    {
+        if (hostServices?.GetService(typeof(TService)) is TService service)
+        {
+            services.AddSingleton(service);
+        }
+    }
+
+    private static HostBuilderContext CreateHostBuilderContext(PluginRuntimeContext runtimeContext)
+    {
+        var hostBuilderContext = new HostBuilderContext(new Dictionary<object, object>());
+        hostBuilderContext.Properties["LanMountainDesktop.PluginManifest"] = runtimeContext.Manifest;
+        hostBuilderContext.Properties["LanMountainDesktop.PluginDirectory"] = runtimeContext.PluginDirectory;
+        hostBuilderContext.Properties["LanMountainDesktop.PluginDataDirectory"] = runtimeContext.DataDirectory;
+        hostBuilderContext.Properties["LanMountainDesktop.PluginRuntimeContext"] = runtimeContext;
+
+        foreach (var pair in runtimeContext.Properties)
+        {
+            if (pair.Value is not null)
+            {
+                hostBuilderContext.Properties[pair.Key] = pair.Value;
+            }
+        }
+
+        return hostBuilderContext;
+    }
+
+    private static IReadOnlyList<PluginServiceExportDescriptor> ResolveExports(
+        PluginManifest manifest,
+        IServiceProvider services)
+    {
+        return services
+            .GetServices<PluginServiceExportRegistration>()
+            .Select(registration =>
+            {
+                if (!IsSupportedExportContract(manifest, registration.ContractType))
+                {
+                    throw new InvalidOperationException(
+                        $"Plugin '{manifest.Id}' exported contract '{registration.ContractType.FullName}', but export contracts must come from LanMountainDesktop.PluginSdk or a manifest-declared shared contract assembly.");
+                }
+
+                return new PluginServiceExportDescriptor(
+                    manifest.Id,
+                    registration.ContractType,
+                    services.GetService(registration.ContractType)
+                        ?? throw new InvalidOperationException(
+                            $"Plugin '{manifest.Id}' exported contract '{registration.ContractType.FullName}', but no singleton service instance was registered."));
+            })
+            .ToArray();
+    }
+
+    private static bool IsSupportedExportContract(PluginManifest manifest, Type contractType)
+    {
+        if (contractType.Assembly == typeof(IPlugin).Assembly)
+        {
+            return true;
+        }
+
+        var assemblyFileName = contractType.Assembly.GetName().Name + ".dll";
+        return manifest.SharedContracts?.Any(contract =>
+            string.Equals(contract.AssemblyName, assemblyFileName, StringComparison.OrdinalIgnoreCase)) == true;
+    }
+
+    private static void StartHostedServices(IEnumerable<IHostedService> hostedServices)
+    {
+        foreach (var hostedService in hostedServices)
+        {
+            hostedService.StartAsync(CancellationToken.None).GetAwaiter().GetResult();
+        }
+    }
+
+    private static void StopHostedServices(IEnumerable<IHostedService> hostedServices)
+    {
+        foreach (var hostedService in hostedServices.Reverse())
+        {
+            try
+            {
+                hostedService.StopAsync(CancellationToken.None).GetAwaiter().GetResult();
+            }
+            catch
+            {
+                // Ignore best-effort shutdown during failed startup.
+            }
+        }
+    }
+
     private IReadOnlyList<PluginCandidate> DiscoverCandidates(
         string pluginsRootDirectory,
         List<PluginLoadResult> preparationFailures)
@@ -436,6 +570,27 @@ public sealed class PluginLoader
         return new ReadOnlyDictionary<string, object?>(map);
     }
 
+    private static void ValidatePluginRuntimeAssets(
+        PluginManifest manifest,
+        string assemblyPath,
+        string pluginDirectory)
+    {
+        var depsFilePath = Path.ChangeExtension(assemblyPath, ".deps.json");
+        if (!File.Exists(depsFilePath))
+        {
+            throw new InvalidOperationException(
+                $"Plugin '{manifest.Id}' targets API {PluginSdkInfo.ApiVersion} and must include '{Path.GetFileName(depsFilePath)}' next to its main assembly.");
+        }
+
+        var runtimesDirectory = Path.Combine(pluginDirectory, "runtimes");
+        if (Directory.Exists(runtimesDirectory) &&
+            !Directory.EnumerateFiles(runtimesDirectory, "*", SearchOption.AllDirectories).Any())
+        {
+            throw new InvalidOperationException(
+                $"Plugin '{manifest.Id}' contains an empty 'runtimes' directory. Native/runtime assets must be packaged together with the plugin.");
+        }
+    }
+
     private static Type ResolvePluginType(Assembly assembly)
     {
         var candidateTypes = GetLoadableTypes(assembly)
@@ -543,34 +698,19 @@ public sealed class PluginLoader
         }
     }
 
-    private sealed class PluginContext : IPluginContext, IDisposable, IAsyncDisposable
+    private sealed class PluginRuntimeContext : IPluginRuntimeContext
     {
-        private readonly Dictionary<string, PluginSettingsPageRegistration> _settingsPages =
+        public PluginRuntimeContext(
-            new(StringComparer.OrdinalIgnoreCase);
-        private readonly Dictionary<string, PluginDesktopComponentRegistration> _desktopComponents =
-            new(StringComparer.OrdinalIgnoreCase);
-        private readonly Dictionary<Type, object> _registeredServices = [];
-        private readonly List<object> _serviceRegistrationOrder = [];
-        private readonly object _serviceGate = new();
-        private readonly IServiceProvider _hostServices;
-        private int _disposed;
-
-        public PluginContext(
             PluginManifest manifest,
             string pluginDirectory,
             string dataDirectory,
-            IServiceProvider services,
             IReadOnlyDictionary<string, object?> properties)
         {
             Manifest = manifest;
             PluginDirectory = pluginDirectory;
             DataDirectory = dataDirectory;
-            _hostServices = services;
-            Services = new PluginCompositeServiceProvider(this);
             Properties = properties;
-
+            Services = NullServiceProvider.Instance;
-            RegisterBuiltInService<IPluginContext>(this);
-            RegisterBuiltInService<IPluginMessageBus>(new PluginMessageBus());
         }
 
         public PluginManifest Manifest { get; }
@@ -579,7 +719,7 @@ public sealed class PluginLoader
 
         public string DataDirectory { get; }
 
-        public IServiceProvider Services { get; }
+        public IServiceProvider Services { get; private set; }
 
         public IReadOnlyDictionary<string, object?> Properties { get; }
 
@@ -602,181 +742,9 @@ public sealed class PluginLoader
             return false;
         }
 
-        public void RegisterService<TService>(TService service)
+        public void SetServices(IServiceProvider services)
-            where TService : class
         {
-            RegisterServiceCore(typeof(TService), service, allowOverride: false);
+            Services = services ?? throw new ArgumentNullException(nameof(services));
-        }
-
-        public void RegisterSettingsPage(PluginSettingsPageRegistration registration)
-        {
-            ArgumentNullException.ThrowIfNull(registration);
-            ThrowIfDisposed();
-
-            if (!_settingsPages.TryAdd(registration.Id, registration))
-            {
-                throw new InvalidOperationException(
-                    $"Plugin '{Manifest.Id}' already registered a settings page with id '{registration.Id}'.");
-            }
-        }
-
-        public void RegisterDesktopComponent(PluginDesktopComponentRegistration registration)
-        {
-            ArgumentNullException.ThrowIfNull(registration);
-            ThrowIfDisposed();
-
-            if (!_desktopComponents.TryAdd(registration.ComponentId, registration))
-            {
-                throw new InvalidOperationException(
-                    $"Plugin '{Manifest.Id}' already registered a desktop component with id '{registration.ComponentId}'.");
-            }
-        }
-
-        public IReadOnlyList<PluginSettingsPageRegistration> GetSettingsPagesSnapshot()
-        {
-            ThrowIfDisposed();
-            return _settingsPages.Values
-                .OrderBy(page => page.SortOrder)
-                .ThenBy(page => page.Title, StringComparer.OrdinalIgnoreCase)
-                .ToArray();
-        }
-
-        public IReadOnlyList<PluginDesktopComponentRegistration> GetDesktopComponentsSnapshot()
-        {
-            ThrowIfDisposed();
-            return _desktopComponents.Values
-                .OrderBy(component => component.Category, StringComparer.OrdinalIgnoreCase)
-                .ThenBy(component => component.DisplayName, StringComparer.OrdinalIgnoreCase)
-                .ToArray();
-        }
-
-        internal object? ResolveService(Type serviceType)
-        {
-            if (Volatile.Read(ref _disposed) != 0)
-            {
-                return null;
-            }
-
-            if (serviceType == typeof(IServiceProvider))
-            {
-                return Services;
-            }
-
-            lock (_serviceGate)
-            {
-                if (_registeredServices.TryGetValue(serviceType, out var service))
-                {
-                    return service;
-                }
-
-                foreach (var registeredService in _registeredServices.Values)
-                {
-                    if (serviceType.IsInstanceOfType(registeredService))
-                    {
-                        return registeredService;
-                    }
-                }
-            }
-
-            return _hostServices.GetService(serviceType);
-        }
-
-        private void RegisterBuiltInService<TService>(TService service)
-            where TService : class
-        {
-            RegisterServiceCore(typeof(TService), service, allowOverride: true);
-        }
-
-        public void Dispose()
-        {
-            DisposeAsync().AsTask().GetAwaiter().GetResult();
-        }
-
-        public async ValueTask DisposeAsync()
-        {
-            if (Interlocked.Exchange(ref _disposed, 1) != 0)
-            {
-                return;
-            }
-
-            object[] services;
-            lock (_serviceGate)
-            {
-                services = _serviceRegistrationOrder.ToArray();
-                _registeredServices.Clear();
-                _serviceRegistrationOrder.Clear();
-            }
-
-            _settingsPages.Clear();
-            _desktopComponents.Clear();
-
-            var disposedServices = new HashSet<object>(ReferenceEqualityComparer.Instance);
-            for (var i = services.Length - 1; i >= 0; i--)
-            {
-                var service = services[i];
-                if (ReferenceEquals(service, this) || !disposedServices.Add(service))
-                {
-                    continue;
-                }
-
-                if (service is IAsyncDisposable asyncDisposable)
-                {
-                    await asyncDisposable.DisposeAsync();
-                }
-                else if (service is IDisposable disposable)
-                {
-                    disposable.Dispose();
-                }
-            }
-        }
-
-        private void RegisterServiceCore(Type serviceType, object service, bool allowOverride)
-        {
-            ArgumentNullException.ThrowIfNull(serviceType);
-            ArgumentNullException.ThrowIfNull(service);
-            ThrowIfDisposed();
-
-            if (!serviceType.IsInstanceOfType(service))
-            {
-                throw new InvalidOperationException(
-                    $"Service instance '{service.GetType().FullName}' is not assignable to '{serviceType.FullName}'.");
-            }
-
-            lock (_serviceGate)
-            {
-                if (!allowOverride && _registeredServices.ContainsKey(serviceType))
-                {
-                    throw new InvalidOperationException(
-                        $"Plugin '{Manifest.Id}' already registered a service for '{serviceType.FullName}'.");
-                }
-
-                _registeredServices[serviceType] = service;
-                _serviceRegistrationOrder.Add(service);
-            }
-        }
-
-        private void ThrowIfDisposed()
-        {
-            if (Volatile.Read(ref _disposed) != 0)
-            {
-                throw new ObjectDisposedException(nameof(PluginContext));
-            }
-        }
-    }
-
-    private sealed class PluginCompositeServiceProvider : IServiceProvider
-    {
-        private readonly PluginContext _context;
-
-        public PluginCompositeServiceProvider(PluginContext context)
-        {
-            _context = context;
-        }
-
-        public object? GetService(Type serviceType)
-        {
-            ArgumentNullException.ThrowIfNull(serviceType);
-            return _context.ResolveService(serviceType);
         }
     }
 

LanMountainDesktop/plugins/PluginMarketModels.cs

@@ -215,6 +215,8 @@ internal sealed class AirAppMarketIndexDocument
 
     public DateTimeOffset GeneratedAt { get; init; }
 
+    public List<AirAppMarketSharedContractEntry> Contracts { get; init; } = [];
+
     public List<AirAppMarketPluginEntry> Plugins { get; init; } = [];
 
     public static AirAppMarketIndexDocument Load(string json, string sourceName)
@@ -236,6 +238,23 @@ internal sealed class AirAppMarketIndexDocument
 
     private AirAppMarketIndexDocument ValidateAndNormalize(string sourceName)
     {
+        var contracts = Contracts ?? [];
+        var normalizedContracts = new List<AirAppMarketSharedContractEntry>(contracts.Count);
+        var seenContracts = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+
+        foreach (var contract in contracts)
+        {
+            var normalizedContract = contract.ValidateAndNormalize(sourceName);
+            var contractKey = $"{normalizedContract.Id}@{normalizedContract.Version}";
+            if (!seenContracts.Add(contractKey))
+            {
+                throw new InvalidOperationException(
+                    $"Market index '{sourceName}' contains duplicate shared contract '{contractKey}'.");
+            }
+
+            normalizedContracts.Add(normalizedContract);
+        }
+
         var plugins = Plugins ?? [];
         var normalizedPlugins = new List<AirAppMarketPluginEntry>(plugins.Count);
         var seenIds = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
@@ -260,6 +279,10 @@ internal sealed class AirAppMarketIndexDocument
             GeneratedAt = GeneratedAt == default
                 ? throw new InvalidOperationException($"Market index '{sourceName}' is missing a valid generatedAt timestamp.")
                 : GeneratedAt,
+            Contracts = normalizedContracts
+                .OrderBy(contract => contract.Id, StringComparer.OrdinalIgnoreCase)
+                .ThenBy(contract => contract.Version, StringComparer.OrdinalIgnoreCase)
+                .ToList(),
             Plugins = normalizedPlugins
                 .OrderBy(plugin => plugin.Name, StringComparer.OrdinalIgnoreCase)
                 .ToList()
@@ -373,6 +396,56 @@ internal sealed class AirAppMarketIndexDocument
     }
 }
 
+internal sealed class AirAppMarketSharedContractEntry
+{
+    public string Id { get; init; } = string.Empty;
+
+    public string Version { get; init; } = string.Empty;
+
+    public string AssemblyName { get; init; } = string.Empty;
+
+    public string DownloadUrl { get; init; } = string.Empty;
+
+    public string Sha256 { get; init; } = string.Empty;
+
+    public long PackageSizeBytes { get; init; }
+
+    public AirAppMarketSharedContractEntry ValidateAndNormalize(string sourceName)
+    {
+        var normalizedSha = AirAppMarketIndexDocument.NormalizeValue(Sha256)?.ToLowerInvariant()
+            ?? throw new InvalidOperationException(
+                $"Market index '{sourceName}' is missing required property '{nameof(Sha256)}' for a shared contract.");
+        if (normalizedSha.Length != 64 || normalizedSha.Any(ch => !Uri.IsHexDigit(ch)))
+        {
+            throw new InvalidOperationException(
+                $"Market index '{sourceName}' declares invalid SHA-256 '{normalizedSha}' for shared contract '{Id}'.");
+        }
+
+        var normalizedDownloadUrl = AirAppMarketIndexDocument.NormalizeValue(DownloadUrl)
+            ?? throw new InvalidOperationException(
+                $"Market index '{sourceName}' is missing required property '{nameof(DownloadUrl)}' for shared contract '{Id}'.");
+        AirAppMarketIndexDocument.EnsureUrl(normalizedDownloadUrl, nameof(DownloadUrl), sourceName);
+
+        if (PackageSizeBytes <= 0)
+        {
+            throw new InvalidOperationException(
+                $"Market index '{sourceName}' declares invalid packageSizeBytes '{PackageSizeBytes}' for shared contract '{Id}'.");
+        }
+
+        return new AirAppMarketSharedContractEntry
+        {
+            Id = AirAppMarketIndexDocument.NormalizeValue(Id)
+                ?? throw new InvalidOperationException($"Market index '{sourceName}' is missing a shared contract id."),
+            Version = AirAppMarketIndexDocument.NormalizeVersion(Version, nameof(Version), sourceName),
+            AssemblyName = AirAppMarketIndexDocument.NormalizeValue(AssemblyName)
+                ?? throw new InvalidOperationException($"Market index '{sourceName}' is missing assemblyName for shared contract '{Id}'."),
+            DownloadUrl = normalizedDownloadUrl,
+            Sha256 = normalizedSha,
+            PackageSizeBytes = PackageSizeBytes
+        };
+    }
+}
+
 internal sealed class AirAppMarketPluginEntry
 {
     public string Id { get; init; } = string.Empty;

LanMountainDesktop/plugins/PluginRuntimeService.cs

@@ -12,6 +12,8 @@ using Avalonia.Markup.Xaml;
 using LanMountainDesktop.Models;
 using LanMountainDesktop.Plugins;
 using LanMountainDesktop.PluginSdk;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
 
 namespace LanMountainDesktop.Services;
 
@@ -19,9 +21,12 @@ public sealed class PluginRuntimeService : IDisposable
 {
     private const string PendingDeletionFileName = ".pending-plugin-deletions.json";
 
+    private readonly PluginLoaderOptions _loaderOptions;
     private readonly PluginLoader _loader;
     private readonly AppSettingsService _appSettingsService = new();
     private readonly IHostApplicationLifecycle _applicationLifecycle = new HostApplicationLifecycleService();
+    private readonly PluginExportRegistry _exportRegistry = new();
+    private readonly PluginSharedContractManager _sharedContractManager;
     private readonly IServiceProvider _hostServices;
     private readonly IPluginPackageManager _packageManager;
     private readonly List<LoadedPlugin> _loadedPlugins = [];
@@ -34,9 +39,12 @@ public sealed class PluginRuntimeService : IDisposable
     public PluginRuntimeService()
     {
         PluginsDirectory = Path.Combine(AppContext.BaseDirectory, "Extensions", "Plugins");
+        _sharedContractManager = new PluginSharedContractManager(
+            Path.Combine(GetUserDataRootDirectory(), "PluginMarket"));
         _packageManager = new PluginRuntimePackageManager(this);
-        _hostServices = new PluginHostServiceProvider(_packageManager, _applicationLifecycle);
+        _hostServices = new PluginHostServiceProvider(_packageManager, _applicationLifecycle, _exportRegistry);
-        _loader = new PluginLoader(CreateOptions());
+        _loaderOptions = CreateOptions();
+        _loader = new PluginLoader(_loaderOptions);
     }
 
     public string PluginsDirectory { get; }
@@ -51,6 +59,8 @@ public sealed class PluginRuntimeService : IDisposable
 
     public IReadOnlyList<PluginDesktopComponentContribution> DesktopComponents => _desktopComponents;
 
+    public IPluginExportRegistry ExportRegistry => _exportRegistry;
+
     public void LoadInstalledPlugins()
     {
         Directory.CreateDirectory(PluginsDirectory);
@@ -101,6 +111,27 @@ public sealed class PluginRuntimeService : IDisposable
                 continue;
             }
 
+            try
+            {
+                RegisterSharedContractsForLoad(candidate.Manifest);
+            }
+            catch (Exception ex)
+            {
+                var dependencyFailure = PluginLoadResult.Failure(candidate.SourcePath, candidate.Manifest, ex);
+                _loadResults.Add(dependencyFailure);
+                _catalog.Add(new PluginCatalogEntry(
+                    candidate.Manifest,
+                    candidate.SourcePath,
+                    candidate.SourceKind == PluginCatalogSourceKind.Package,
+                    true,
+                    false,
+                    ex.Message,
+                    0,
+                    0));
+                Debug.WriteLine($"[PluginRuntime] Failed to prepare dependencies for '{candidate.Manifest.Id}': {ex}");
+                continue;
+            }
+
             var loadResult = candidate.SourceKind switch
             {
                 PluginCatalogSourceKind.Package => _loader.LoadFromPackage(
@@ -277,6 +308,7 @@ public sealed class PluginRuntimeService : IDisposable
         Directory.CreateDirectory(PluginsDirectory);
 
         var manifest = ReadManifestFromPackage(fullPackagePath);
+        _sharedContractManager.EnsureInstalled(manifest);
         AppLogger.Info(
             "PluginRuntime",
             $"Installing package. PluginId='{manifest.Id}'; Source='{fullPackagePath}'; PluginsDirectory='{PluginsDirectory}'.");
@@ -308,6 +340,7 @@ public sealed class PluginRuntimeService : IDisposable
         }
 
         var manifest = ReadManifestFromPackage(fullPackagePath);
+        _sharedContractManager.EnsureInstalled(manifest);
         AppLogger.Info(
             "PluginRuntime",
             $"Registering externally installed package. PluginId='{manifest.Id}'; Source='{fullPackagePath}'.");
@@ -319,16 +352,19 @@ public sealed class PluginRuntimeService : IDisposable
     public void Dispose()
     {
         UnloadInstalledPlugins();
+        _sharedContractManager.Dispose();
     }
 
     private void UnloadInstalledPlugins()
     {
         for (var i = _loadedPlugins.Count - 1; i >= 0; i--)
         {
+            _exportRegistry.RemoveExports(_loadedPlugins[i].Manifest.Id);
             _loadedPlugins[i].Dispose();
         }
 
         _loadedPlugins.Clear();
+        _exportRegistry.Clear();
         _loadResults.Clear();
         _catalog.Clear();
         _settingsPages.Clear();
@@ -483,10 +519,23 @@ public sealed class PluginRuntimeService : IDisposable
             : path + Path.DirectorySeparatorChar;
     }
 
+    private static string GetUserDataRootDirectory()
+    {
+        var localAppData = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);
+        if (string.IsNullOrWhiteSpace(localAppData))
+        {
+            return Path.Combine(AppContext.BaseDirectory, "Data");
+        }
+
+        return Path.Combine(localAppData, "LanMountainDesktop");
+    }
+
     private static PluginLoaderOptions CreateOptions()
     {
         var options = new PluginLoaderOptions();
         AddSharedAssembly(options, typeof(App).Assembly);
+        AddSharedAssembly(options, typeof(IServiceCollection).Assembly);
+        AddSharedAssembly(options, typeof(HostBuilderContext).Assembly);
 
         foreach (var assembly in AppDomain.CurrentDomain.GetAssemblies())
         {
@@ -517,6 +566,8 @@ public sealed class PluginRuntimeService : IDisposable
 
     private void CollectContributions(LoadedPlugin loadedPlugin)
     {
+        _exportRegistry.ReplaceExports(loadedPlugin.Manifest.Id, loadedPlugin.ExportedServices);
+
         foreach (var settingsPage in loadedPlugin.SettingsPages)
         {
             _settingsPages.Add(new PluginSettingsPageContribution(loadedPlugin, settingsPage));
@@ -528,6 +579,17 @@ public sealed class PluginRuntimeService : IDisposable
         }
     }
 
+    private void RegisterSharedContractsForLoad(PluginManifest manifest)
+    {
+        foreach (var assemblyName in _sharedContractManager.PrepareForLoad(manifest))
+        {
+            if (!string.IsNullOrWhiteSpace(assemblyName))
+            {
+                _loaderOptions.SharedAssemblyNames.Add(assemblyName);
+            }
+        }
+    }
+
     private void ApplyPendingPluginDeletions()
     {
         var pendingPaths = ReadPendingPluginDeletions();
@@ -681,13 +743,16 @@ public sealed class PluginRuntimeService : IDisposable
     {
         private readonly IPluginPackageManager _packageManager;
         private readonly IHostApplicationLifecycle _applicationLifecycle;
+        private readonly IPluginExportRegistry _exportRegistry;
 
         public PluginHostServiceProvider(
             IPluginPackageManager packageManager,
-            IHostApplicationLifecycle applicationLifecycle)
+            IHostApplicationLifecycle applicationLifecycle,
+            IPluginExportRegistry exportRegistry)
         {
             _packageManager = packageManager;
             _applicationLifecycle = applicationLifecycle;
+            _exportRegistry = exportRegistry;
         }
 
         public object? GetService(Type serviceType)
@@ -702,6 +767,11 @@ public sealed class PluginRuntimeService : IDisposable
                 return _applicationLifecycle;
             }
 
+            if (serviceType == typeof(IPluginExportRegistry))
+            {
+                return _exportRegistry;
+            }
+
             return null;
         }
     }

LanMountainDesktop/plugins/PluginSharedContractManager.cs

@@ -0,0 +1,272 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Net.Http;
+using System.Reflection;
+using System.Runtime.Loader;
+using System.Security.Cryptography;
+using System.Threading;
+using LanMountainDesktop.PluginSdk;
+using LanMountainDesktop.Views.SettingsPages;
+
+namespace LanMountainDesktop.Plugins;
+
+internal sealed class PluginSharedContractManager : IDisposable
+{
+    private readonly string _contractsDirectory;
+    private readonly AirAppMarketIndexService _indexService;
+    private readonly HttpClient _httpClient;
+    private readonly object _gate = new();
+    private readonly Dictionary<string, LoadedSharedContract> _loadedContracts =
+        new(StringComparer.OrdinalIgnoreCase);
+
+    public PluginSharedContractManager(string cacheDirectory)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(cacheDirectory);
+
+        _contractsDirectory = Path.Combine(
+            GetSharedContractRootDirectory(),
+            "SharedContracts");
+        _indexService = new AirAppMarketIndexService(new AirAppMarketCacheService(cacheDirectory));
+        _httpClient = new HttpClient
+        {
+            Timeout = TimeSpan.FromMinutes(2)
+        };
+        _httpClient.DefaultRequestHeaders.UserAgent.ParseAdd("LanMountainDesktop-SharedContracts/1.0");
+    }
+
+    public string ContractsDirectory => _contractsDirectory;
+
+    public void EnsureInstalled(PluginManifest manifest, CancellationToken cancellationToken = default)
+    {
+        ArgumentNullException.ThrowIfNull(manifest);
+
+        if (manifest.SharedContracts is not { Count: > 0 })
+        {
+            return;
+        }
+
+        var document = LoadIndex(cancellationToken);
+        foreach (var reference in manifest.SharedContracts)
+        {
+            EnsureInstalled(document, reference, cancellationToken);
+        }
+    }
+
+    public IReadOnlyList<string> PrepareForLoad(PluginManifest manifest, CancellationToken cancellationToken = default)
+    {
+        ArgumentNullException.ThrowIfNull(manifest);
+
+        if (manifest.SharedContracts is not { Count: > 0 })
+        {
+            return Array.Empty<string>();
+        }
+
+        var assemblyNames = new List<string>(manifest.SharedContracts.Count);
+        foreach (var reference in manifest.SharedContracts)
+        {
+            var assemblyPath = GetInstalledAssemblyPath(reference);
+            if (!File.Exists(assemblyPath))
+            {
+                throw new InvalidOperationException(
+                    $"Plugin '{manifest.Id}' requires shared contract '{reference.Id}' version '{reference.Version}', but '{assemblyPath}' is not installed. Install the dependency from the market first.");
+            }
+
+            var loaded = LoadSharedAssembly(reference, assemblyPath);
+            assemblyNames.Add(loaded.AssemblyName);
+        }
+
+        return assemblyNames;
+    }
+
+    public void Dispose()
+    {
+        _httpClient.Dispose();
+        _indexService.Dispose();
+    }
+
+    private void EnsureInstalled(
+        AirAppMarketIndexDocument document,
+        PluginSharedContractReference reference,
+        CancellationToken cancellationToken)
+    {
+        var entry = document.Contracts.FirstOrDefault(candidate =>
+            string.Equals(candidate.Id, reference.Id, StringComparison.OrdinalIgnoreCase) &&
+            string.Equals(candidate.Version, reference.Version, StringComparison.OrdinalIgnoreCase));
+        if (entry is null)
+        {
+            throw new InvalidOperationException(
+                $"Shared contract '{reference.Id}' version '{reference.Version}' is not published in the configured market index.");
+        }
+
+        if (!string.Equals(entry.AssemblyName, reference.AssemblyName, StringComparison.OrdinalIgnoreCase))
+        {
+            throw new InvalidOperationException(
+                $"Shared contract '{reference.Id}' version '{reference.Version}' expects assembly '{reference.AssemblyName}', but the market entry provides '{entry.AssemblyName}'.");
+        }
+
+        var destinationPath = GetInstalledAssemblyPath(reference);
+        if (IsInstalledAndMatches(destinationPath, entry))
+        {
+            return;
+        }
+
+        Directory.CreateDirectory(Path.GetDirectoryName(destinationPath)!);
+
+        var temporaryPath = destinationPath + ".download";
+        try
+        {
+            if (AirAppMarketDefaults.TryResolveWorkspaceFile(entry.DownloadUrl, out var localSourcePath))
+            {
+                File.Copy(localSourcePath, temporaryPath, overwrite: true);
+            }
+            else
+            {
+                using var response = _httpClient.GetAsync(entry.DownloadUrl, cancellationToken)
+                    .GetAwaiter()
+                    .GetResult();
+                response.EnsureSuccessStatusCode();
+                using var responseStream = response.Content.ReadAsStreamAsync(cancellationToken)
+                    .GetAwaiter()
+                    .GetResult();
+                using var fileStream = File.Create(temporaryPath);
+                responseStream.CopyTo(fileStream);
+            }
+
+            ValidateInstalledFile(temporaryPath, entry);
+            File.Move(temporaryPath, destinationPath, overwrite: true);
+        }
+        finally
+        {
+            TryDeleteFile(temporaryPath);
+        }
+    }
+
+    private AirAppMarketIndexDocument LoadIndex(CancellationToken cancellationToken)
+    {
+        var result = _indexService.LoadAsync(cancellationToken).GetAwaiter().GetResult();
+        if (!result.Success || result.Document is null)
+        {
+            throw new InvalidOperationException(
+                $"Failed to load market index for shared contract resolution: {result.ErrorMessage ?? "Unknown error"}");
+        }
+
+        return result.Document;
+    }
+
+    private LoadedSharedContract LoadSharedAssembly(
+        PluginSharedContractReference reference,
+        string assemblyPath)
+    {
+        var assemblyName = AssemblyLoadContext.GetAssemblyName(assemblyPath).Name
+            ?? throw new InvalidOperationException($"Failed to determine assembly name of '{assemblyPath}'.");
+
+        lock (_gate)
+        {
+            if (_loadedContracts.TryGetValue(assemblyName, out var existing))
+            {
+                if (!string.Equals(existing.ContractId, reference.Id, StringComparison.OrdinalIgnoreCase) ||
+                    !string.Equals(existing.ContractVersion, reference.Version, StringComparison.OrdinalIgnoreCase))
+                {
+                    throw new InvalidOperationException(
+                        $"Shared contract assembly '{assemblyName}' is already loaded as '{existing.ContractId}' version '{existing.ContractVersion}', so plugin dependency '{reference.Id}' version '{reference.Version}' cannot be activated in the same host process.");
+                }
+
+                return existing;
+            }
+
+            var assembly = AssemblyLoadContext.Default.Assemblies.FirstOrDefault(candidate =>
+                string.Equals(candidate.GetName().Name, assemblyName, StringComparison.OrdinalIgnoreCase))
+                ?? AssemblyLoadContext.Default.LoadFromAssemblyPath(assemblyPath);
+
+            var loaded = new LoadedSharedContract(reference.Id, reference.Version, assemblyName, assemblyPath, assembly);
+            _loadedContracts[assemblyName] = loaded;
+            return loaded;
+        }
+    }
+
+    private static bool IsInstalledAndMatches(string assemblyPath, AirAppMarketSharedContractEntry entry)
+    {
+        if (!File.Exists(assemblyPath))
+        {
+            return false;
+        }
+
+        try
+        {
+            ValidateInstalledFile(assemblyPath, entry);
+            return true;
+        }
+        catch
+        {
+            return false;
+        }
+    }
+
+    private static void ValidateInstalledFile(string assemblyPath, AirAppMarketSharedContractEntry entry)
+    {
+        var actualSize = new FileInfo(assemblyPath).Length;
+        if (actualSize != entry.PackageSizeBytes)
+        {
+            throw new InvalidOperationException(
+                $"Shared contract '{entry.Id}' version '{entry.Version}' size mismatch. Expected {entry.PackageSizeBytes}, actual {actualSize}.");
+        }
+
+        using var stream = File.OpenRead(assemblyPath);
+        var actualHash = Convert.ToHexString(SHA256.HashData(stream)).ToLowerInvariant();
+        if (!string.Equals(actualHash, entry.Sha256, StringComparison.OrdinalIgnoreCase))
+        {
+            throw new InvalidOperationException(
+                $"Shared contract '{entry.Id}' version '{entry.Version}' hash mismatch. Expected {entry.Sha256}, actual {actualHash}.");
+        }
+    }
+
+    private string GetInstalledAssemblyPath(PluginSharedContractReference reference)
+    {
+        return Path.Combine(
+            _contractsDirectory,
+            Sanitize(reference.Id),
+            Sanitize(reference.Version),
+            reference.AssemblyName);
+    }
+
+    private static string GetSharedContractRootDirectory()
+    {
+        var localAppData = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);
+        if (string.IsNullOrWhiteSpace(localAppData))
+        {
+            return Path.Combine(AppContext.BaseDirectory, "Data");
+        }
+
+        return Path.Combine(localAppData, "LanMountainDesktop");
+    }
+
+    private static string Sanitize(string value)
+    {
+        var invalidChars = Path.GetInvalidFileNameChars();
+        return new string(value.Select(ch => invalidChars.Contains(ch) ? '_' : ch).ToArray());
+    }
+
+    private static void TryDeleteFile(string path)
+    {
+        try
+        {
+            if (File.Exists(path))
+            {
+                File.Delete(path);
+            }
+        }
+        catch
+        {
+            // Ignore cleanup failures.
+        }
+    }
+
+    private sealed record LoadedSharedContract(
+        string ContractId,
+        string ContractVersion,
+        string AssemblyName,
+        string AssemblyPath,
+        Assembly Assembly);
+}

LanMountainDesktop/plugins/README.md

@@ -47,6 +47,9 @@ This directory contains the host-side plugin runtime for LanMountainDesktop.
 - load plugin assemblies
 - integrate plugin settings pages and desktop components
 - expose market and plugin management in the host UI
+- build a plugin-scoped `IServiceCollection`/`ServiceProvider` for API `2.0.0` plugins
+- resolve shared contract assemblies into a version-isolated cache before plugin activation
+- expose explicit cross-plugin exports through `IPluginExportRegistry`
 
 ### Market install order
 
@@ -55,3 +58,9 @@ This directory contains the host-side plugin runtime for LanMountainDesktop.
 3. If Release resolution fails, the host falls back to the repository root `.laapp` from `downloadUrl`.
 4. Plugin details always come from the repository root `README.md`.
 5. Market installs are staged and take effect after restart.
+
+### Dependency model
+
+- Plugin-private managed and native NuGet dependencies remain plugin-local and are resolved through `AssemblyDependencyResolver`.
+- Shared contract assemblies are downloaded from the official market index, cached under `LocalAppData/LanMountainDesktop/SharedContracts/<id>/<version>/`, and loaded into the default context so host and plugins share the same contract types.
+- Different contract versions are isolated on disk. If two active plugins request incompatible versions of the same shared assembly name in one process, the host fails the later activation with a clear error instead of loading an ambiguous contract.

LanMountainDesktop/plugins/SettingsWindow.PluginSettingsHost.cs

@@ -77,7 +77,7 @@ public partial class SettingsWindow
         Control content;
         try
         {
-            content = contribution.Registration.ContentFactory();
+            content = contribution.Registration.ContentFactory(contribution.Plugin.Services);
         }
         catch (Exception ex)
         {