feat: a2a support

BotSharp.sln

@@ -153,7 +153,7 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "BotSharp.Plugin.MMPEmbeddin
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "BotSharp.Plugin.Membase", "src\Plugins\BotSharp.Plugin.Membase\BotSharp.Plugin.Membase.csproj", "{13223C71-9EAC-9835-28ED-5A4833E6F915}"
 EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "MultiTenancy", "MultiTenancy", "{7C64208C-8D11-4E17-A3E9-14D7910763EB}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "BotSharp.Core.A2A", "src\Infrastructure\BotSharp.Core.A2A\BotSharp.Core.A2A.csproj", "{E8D01281-D52A-BFF4-33DB-E35D91754272}"
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "BotSharp.Plugin.MultiTenancy", "src\Plugins\BotSharp.Plugin.MultiTenancy\BotSharp.Plugin.MultiTenancy.csproj", "{9BC8DF43-88D1-4C57-A678-AC0153BDF4EB}"
 EndProject
@@ -653,6 +653,14 @@ Global
 		{13223C71-9EAC-9835-28ED-5A4833E6F915}.Release|Any CPU.Build.0 = Release|Any CPU
 		{13223C71-9EAC-9835-28ED-5A4833E6F915}.Release|x64.ActiveCfg = Release|Any CPU
 		{13223C71-9EAC-9835-28ED-5A4833E6F915}.Release|x64.Build.0 = Release|Any CPU
+		{E8D01281-D52A-BFF4-33DB-E35D91754272}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{E8D01281-D52A-BFF4-33DB-E35D91754272}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{E8D01281-D52A-BFF4-33DB-E35D91754272}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{E8D01281-D52A-BFF4-33DB-E35D91754272}.Debug|x64.Build.0 = Debug|Any CPU
+		{E8D01281-D52A-BFF4-33DB-E35D91754272}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{E8D01281-D52A-BFF4-33DB-E35D91754272}.Release|Any CPU.Build.0 = Release|Any CPU
+		{E8D01281-D52A-BFF4-33DB-E35D91754272}.Release|x64.ActiveCfg = Release|Any CPU
+		{E8D01281-D52A-BFF4-33DB-E35D91754272}.Release|x64.Build.0 = Release|Any CPU
 		{9BC8DF43-88D1-4C57-A678-AC0153BDF4EB}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{9BC8DF43-88D1-4C57-A678-AC0153BDF4EB}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{9BC8DF43-88D1-4C57-A678-AC0153BDF4EB}.Debug|x64.ActiveCfg = Debug|Any CPU
@@ -735,7 +743,7 @@ Global
 		{E7C243B9-E751-B3B4-8F16-95C76CA90D31} = {51AFE054-AE99-497D-A593-69BAEFB5106F}
 		{394B858B-9C26-B977-A2DA-8CC7BE5914CB} = {4F346DCE-087F-4368-AF88-EE9C720D0E69}
 		{13223C71-9EAC-9835-28ED-5A4833E6F915} = {53E7CD86-0D19-40D9-A0FA-AB4613837E89}
-		{7C64208C-8D11-4E17-A3E9-14D7910763EB} = {2635EC9B-2E5F-4313-AC21-0B847F31F36C}
+		{E8D01281-D52A-BFF4-33DB-E35D91754272} = {E29DC6C4-5E57-48C5-BCB0-6B8F84782749}
 		{9BC8DF43-88D1-4C57-A678-AC0153BDF4EB} = {7C64208C-8D11-4E17-A3E9-14D7910763EB}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution

Directory.Packages.props

@@ -3,6 +3,7 @@
     <ManagePackageVersionsCentrally>true</ManagePackageVersionsCentrally>
   </PropertyGroup>
   <ItemGroup>
+    <PackageVersion Include="A2A" Version="0.3.3-preview" />
     <PackageVersion Include="CsvHelper" Version="33.1.0" />
     <PackageVersion Include="FuzzySharp" Version="2.0.2" />
     <PackageVersion Include="Google_GenerativeAI" Version="3.4.1" />

src/Infrastructure/BotSharp.Abstraction/Agents/Enums/AgentType.cs

@@ -23,5 +23,10 @@ public static class AgentType
     /// Agent that cannot use external tools
     /// </summary>
     public const string Static = "static";
+
+    /// <summary>
+    /// A2A remote agent for Microsoft Agent Framework integration
+    /// </summary>
+    public const string A2ARemote = "a2a-remote";
 }
 

src/Infrastructure/BotSharp.Core.A2A/A2APlugin.cs

@@ -0,0 +1,36 @@
+using BotSharp.Abstraction.Agents;
+using BotSharp.Abstraction.Conversations;
+using BotSharp.Abstraction.Functions;
+using BotSharp.Abstraction.Plugins;
+using BotSharp.Abstraction.Settings;
+using BotSharp.Core.A2A.Functions;
+using BotSharp.Core.A2A.Hooks;
+using BotSharp.Core.A2A.Services;
+using BotSharp.Core.A2A.Settings;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace BotSharp.Core.A2A;
+
+public class A2APlugin : IBotSharpPlugin
+{
+
+    public string Id => "058cdf87-fcf3-eda9-915a-565c04bc9f56";
+
+    public string Name => "A2A Protocol Integration";
+
+    public string Description => "Enables seamless integration with external agents via the Agent-to-Agent (A2A) protocol.";
+
+    public void RegisterDI(IServiceCollection services, IConfiguration config)
+    { 
+        services.AddScoped(provider =>
+        {
+            var settingService = provider.GetRequiredService<ISettingService>();
+            return settingService.Bind<A2ASettings>("A2AIntegration");
+        });
+
+        services.AddScoped<IA2AService, A2AService>();
+        services.AddScoped<IAgentHook, A2AAgentHook>(); 
+        services.AddScoped<IFunctionCallback, A2ADelegationFn>();
+    }
+}

src/Infrastructure/BotSharp.Core.A2A/BotSharp.Core.A2A.csproj

@@ -0,0 +1,21 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>$(TargetFramework)</TargetFramework>
+    <LangVersion>$(LangVersion)</LangVersion>
+    <VersionPrefix>$(BotSharpVersion)</VersionPrefix>
+    <GeneratePackageOnBuild>$(GeneratePackageOnBuild)</GeneratePackageOnBuild>
+    <OutputPath>$(SolutionDir)packages</OutputPath>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="A2A" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\Infrastructure\BotSharp.Abstraction\BotSharp.Abstraction.csproj" />
+  </ItemGroup>
+
+</Project>

src/Infrastructure/BotSharp.Core.A2A/Functions/A2ADelegationFn.cs

@@ -0,0 +1,65 @@
+using BotSharp.Abstraction.Conversations;
+using BotSharp.Abstraction.Conversations.Models;
+using BotSharp.Abstraction.Functions;
+using BotSharp.Core.A2A.Services;
+using BotSharp.Core.A2A.Settings;
+using System.Text.Json;
+
+namespace BotSharp.Core.A2A.Functions;
+
+public class A2ADelegationFn : IFunctionCallback
+{
+    public string Name => "delegate_to_a2a";
+    public string Indication => "Connecting to external agent network..."; 
+
+    private readonly IA2AService _a2aService;
+    private readonly A2ASettings _settings;
+    private readonly IConversationStateService _stateService;
+
+    public A2ADelegationFn(IA2AService a2aService, A2ASettings settings, IConversationStateService stateService)
+    {
+        _a2aService = a2aService;
+        _settings = settings;
+        _stateService = stateService;
+    }
+
+    public async Task<bool> Execute(RoleDialogModel message)
+    {
+        var args = JsonSerializer.Deserialize<JsonElement>(message.FunctionArgs);
+        string queryText = string.Empty;
+        if (args.TryGetProperty("user_query", out var queryProp))
+        {
+            queryText = queryProp.GetString();
+        }
+
+        var agentId = message.CurrentAgentId;
+        var agentConfig = _settings.Agents.FirstOrDefault(x => x.Id == agentId);
+
+        if (agentConfig == null)
+        {
+            message.Content = "System Error: Remote agent configuration not found.";
+            message.StopCompletion = true;  
+            return false;
+        }
+
+        var conversationId = _stateService.GetConversationId();
+
+        try
+        {
+            var responseText = await _a2aService.SendMessageAsync(
+                agentConfig.Endpoint,
+                queryText,
+                conversationId,
+                CancellationToken.None
+            );
+
+            message.Content = responseText; 
+            return true;
+        }
+        catch (Exception ex)
+        {            
+            message.Content = $"Communication failure with external agent: {ex.Message}";
+            return false;
+        }
+    }
+}

src/Infrastructure/BotSharp.Core.A2A/Hooks/A2AAgentHook.cs

@@ -0,0 +1,85 @@
+using BotSharp.Abstraction.Agents;
+using BotSharp.Abstraction.Agents.Enums;
+using BotSharp.Abstraction.Agents.Models;
+using BotSharp.Abstraction.Agents.Settings;
+using BotSharp.Abstraction.Functions.Models;
+using BotSharp.Core.A2A.Services;
+using BotSharp.Core.A2A.Settings;
+using System.Text.Json;
+
+namespace BotSharp.Core.A2A.Hooks;
+
+public class A2AAgentHook : AgentHookBase
+{
+    public override string SelfId => string.Empty;
+
+    private readonly A2ASettings _settings;
+    private readonly IA2AService _iA2AService;
+
+    public A2AAgentHook(IServiceProvider services, IA2AService a2AService, A2ASettings settings)
+        : base(services, new AgentSettings())
+    {
+        _iA2AService = a2AService;
+        _settings = settings;
+    }
+
+    public override bool OnAgentLoading(ref string id)
+    {
+        var agentId = id;
+        var remoteConfig = _settings.Agents.FirstOrDefault(x => x.Id == agentId);
+        if (remoteConfig != null)
+        {
+            return true;
+        }
+        return base.OnAgentLoading(ref id);
+    }
+
+    public override void OnAgentLoaded(Agent agent)
+    {
+        // Check if this is an A2A remote agent
+        if (agent.Type != AgentType.A2ARemote)
+        {
+            return;
+        }
+
+        var remoteConfig = _settings.Agents.FirstOrDefault(x => x.Id == agent.Id);
+        if (remoteConfig != null)
+        {
+            var agentCard = _iA2AService.GetCapabilitiesAsync(remoteConfig.Endpoint).GetAwaiter().GetResult();
+            agent.Name = agentCard.Name;
+            agent.Description = agentCard.Description;
+            agent.Instruction = $"You are a proxy interface for an external intelligent service named '{agentCard.Name}'. " +
+                                $"Your ONLY goal is to forward the user's request verbatim to the external service. " +
+                                $"You must use the function 'delegate_to_a2a' to communicate with it. " +
+                                $"Do not attempt to answer the question yourself.";
+
+            var properties = new Dictionary<string, object>
+            {
+                {
+                    "user_query",
+                    new
+                    {
+                        type = "string",
+                        description = "The exact user request or task description to be forwarded."
+                    }
+                }
+            };
+
+            var propertiesJson = JsonSerializer.Serialize(properties);
+            var propertiesDocument = JsonDocument.Parse(propertiesJson);
+
+            agent.Functions.Add(new FunctionDef
+            {
+                Name = "delegate_to_a2a",
+                Description = $"Delegates the task to the external {remoteConfig.Name} via A2A protocol.",
+                Parameters = new FunctionParametersDef()
+                {
+                    Type = "object",
+                    Properties = propertiesDocument,
+                    Required = new List<string> { "user_query" }
+                }
+            });
+        }
+        base.OnAgentLoaded(agent);
+    }
+}