chore: import upstream snapshot with attribution

dotnet/samples/02-agents/A2A/A2AAgent_ProtocolSelection/Program.cs

@@ -0,0 +1,36 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+// This sample demonstrates how to select the A2A protocol binding (HTTP+JSON vs JSON-RPC) when
+// creating an AIAgent from an A2A agent card using A2AClientOptions.PreferredBindings.
+
+using A2A;
+using Microsoft.Agents.AI;
+
+var a2aAgentHost = Environment.GetEnvironmentVariable("A2A_AGENT_HOST") ?? throw new InvalidOperationException("A2A_AGENT_HOST is not set.");
+
+// Initialize an A2ACardResolver to get an A2A agent card.
+A2ACardResolver agentCardResolver = new(new Uri(a2aAgentHost));
+
+// Get the agent card
+AgentCard agentCard = await agentCardResolver.GetAgentCardAsync();
+
+// Use A2AClientOptions to explicitly select the HTTP+JSON protocol binding.
+// This tells the A2A client factory to prefer the HTTP+JSON interface when the agent card
+// advertises multiple supported interfaces.
+A2AClientOptions options = new()
+{
+    PreferredBindings = [ProtocolBindingNames.HttpJson]
+};
+
+// To prefer JSON-RPC instead, use:
+// A2AClientOptions options = new()
+// {
+//     PreferredBindings = [ProtocolBindingNames.JsonRpc]
+// };
+
+// Create an instance of the AIAgent for an existing A2A agent, using the specified protocol binding.
+AIAgent agent = agentCard.AsAIAgent(options: options);
+
+// Invoke the agent and output the text result.
+AgentResponse response = await agent.RunAsync("Tell me a joke about a pirate.");
+Console.WriteLine(response);