Refactor A2A client API and migrate to AIAgent integration

.vscode/settings.json

@@ -0,0 +1,3 @@
+{
+    "aspire.enableSettingsFileCreationPromptOnStartup": false
+}

Directory.Packages.props

@@ -3,7 +3,8 @@
     <ManagePackageVersionsCentrally>true</ManagePackageVersionsCentrally>
   </PropertyGroup>
   <ItemGroup>
-    <PackageVersion Include="A2A" Version="0.3.3-preview" />
+    <PackageVersion Include="A2A" Version="1.0.0-preview2" />
+    <PackageVersion Include="Microsoft.Agents.AI.A2A" Version="1.3.0-preview.260423.1" />
     <PackageVersion Include="CsvHelper" Version="33.1.0" />
     <PackageVersion Include="FuzzySharp" Version="2.0.2" />
     <PackageVersion Include="Google_GenerativeAI" Version="3.6.3" />

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

@@ -12,6 +12,7 @@
 
   <ItemGroup>
     <PackageReference Include="A2A" />
+    <PackageReference Include="Microsoft.Agents.AI.A2A" />
   </ItemGroup>
 
   <ItemGroup>

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

@@ -25,11 +25,12 @@ public A2ADelegationFn(IA2AService a2aService, A2ASettings settings, IConversati
 
     public async Task<bool> Execute(RoleDialogModel message)
     {
-        var args = JsonSerializer.Deserialize<JsonElement>(message.FunctionArgs);
+        var rawArgs = string.IsNullOrWhiteSpace(message.FunctionArgs) ? "{}" : message.FunctionArgs;
+        var args = JsonSerializer.Deserialize<JsonElement>(rawArgs);
         string queryText = string.Empty;
         if (args.TryGetProperty("user_query", out var queryProp))
         {
-            queryText = queryProp.GetString();
+            queryText = queryProp.GetString() ?? string.Empty;
         }
 
         var agentId = message.CurrentAgentId;
@@ -43,6 +44,12 @@ public async Task<bool> Execute(RoleDialogModel message)
         }
 
         var conversationId = _stateService.GetConversationId();
+        if (string.IsNullOrWhiteSpace(conversationId))
+        {
+            message.Content = "System Error: Conversation context is unavailable for A2A session continuation.";
+            message.StopCompletion = true;
+            return false;
+        }
 
         try
         {
@@ -54,6 +61,7 @@ public async Task<bool> Execute(RoleDialogModel message)
             );
 
             message.Content = responseText; 
+            message.StopCompletion = true;
             return true;
         }
         catch (Exception ex)

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

@@ -1,10 +1,12 @@
+using A2A;
 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 Microsoft.Extensions.Logging;
 using System.Text.Json;
 
 namespace BotSharp.Core.A2A.Hooks;
@@ -15,12 +17,14 @@ public class A2AAgentHook : AgentHookBase
 
     private readonly A2ASettings _a2aSettings;
     private readonly IA2AService _a2aService;
+    private readonly ILogger<A2AAgentHook> _logger;
 
-    public A2AAgentHook(IServiceProvider services, IA2AService a2aService, A2ASettings a2aSettings, AgentSettings agentSettings)
+    public A2AAgentHook(IServiceProvider services, IA2AService a2aService, A2ASettings a2aSettings, AgentSettings agentSettings, ILogger<A2AAgentHook> logger)
         : base(services, agentSettings)
     {
         _a2aService = a2aService;
         _a2aSettings = a2aSettings;
+        _logger = logger;
     }
 
     public override async Task<string?> OnAgentLoading(string id)
@@ -45,7 +49,16 @@ public override async Task OnAgentLoaded(Agent agent)
         var remoteConfig = _a2aSettings.Agents?.FirstOrDefault(x => x.Id == agent.Id);
         if (remoteConfig != null)
         {
-            var agentCard = await _a2aService.GetCapabilitiesAsync(remoteConfig.Endpoint);
+            AgentCard? agentCard = null;
+            try
+            {
+                agentCard = await _a2aService.GetCapabilitiesAsync(remoteConfig.Endpoint);
+            }
+            catch (Exception ex)
+            {
+                _logger.LogWarning(ex, "Failed to resolve A2A agent card for endpoint {AgentEndpoint}. Using configured metadata.", remoteConfig.Endpoint);
+            }
+
             if (agentCard != null)
             {
                 agent.Name = agentCard.Name;
@@ -54,34 +67,34 @@ public override async Task OnAgentLoaded(Agent agent)
                                     $"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>
+            var properties = new Dictionary<string, object>
+            {
                 {
+                    "user_query",
+                    new
                     {
-                        "user_query",
-                        new
-                        {
-                            type = "string",
-                            description = "The exact user request or task description to be forwarded."
-                        }
+                        type = "string",
+                        description = "The exact user request or task description to be forwarded."
                     }
-                };
+                }
+            };
 
-                var propertiesJson = JsonSerializer.Serialize(properties);
-                var propertiesDocument = JsonDocument.Parse(propertiesJson);
+            var propertiesJson = JsonSerializer.Serialize(properties);
+            var propertiesDocument = JsonDocument.Parse(propertiesJson);
 
-                agent.Functions.Add(new FunctionDef
+            agent.Functions.Add(new FunctionDef
+            {
+                Name = "delegate_to_a2a",
+                Description = $"Delegates the task to the external {remoteConfig.Name} via A2A protocol.",
+                Parameters = new FunctionParametersDef()
                 {
-                    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" }
-                    }
-                });
-            }
+                    Type = "object",
+                    Properties = propertiesDocument,
+                    Required = new List<string> { "user_query" }
+                }
+            });
         }
         await base.OnAgentLoaded(agent);
     }