[SergeyMenshykh]

Motivation & Context

The A2A .NET SDK provides a gRPC client that already works with A2AAgent through IA2AClient. The existing sample and documentation do not show how to use it.

Description & Review Guide

• Add gRPC selection to the protocol-selection sample, with explicit SDK registration and client disposal.
• Reference A2A.Grpc only from the sample; keep the base package's dependencies, public APIs, and hosting unchanged.
• Document direct and discovery-based gRPC setup. Review the binding selection, registration, and client lifetime examples.

AI Assistance

• No material AI assistance was used.
• This is an AI-assisted contribution. I reviewed, understood, and verified all submitted content and accept responsibility for it.

AI assistance details: Copilot helped update the sample, revise the documentation, and prepare this PR description.

Contribution Checklist

• The code builds clean without any errors or warnings
• All unit tests pass, and I have added new tests where possible
• The PR follows the Contribution Guidelines
• This PR links to an agreed issue with no competing open PR, or the Related Issue section documents a trivial-change or repository-automation exception.
• This is not a breaking change. If it is a breaking change, add the breaking change label (or add "[BREAKING]" to the title prefix, before or after any language prefix) — a workflow keeps the label and title prefix in sync automatically.

[Copilot]

🟢 Approval recommended

The scoped sample and documentation changes match the existing integration and pinned SDK behavior, with no blocking issues identified.

No open issues 🎉

What changed in this PR

Adds gRPC selection to the .NET A2A sample using the existing client abstraction, without changing framework behavior or public APIs.

Changes:

• Adds configurable protocol selection, explicit gRPC registration, and client disposal.
• Adds a sample-only gRPC dependency.
• Documents discovery-based and direct gRPC connections.

File	Description
dotnet/​src/​Microsoft.Agents.AI.A2A/​Extensions/​A2ACardResolverExtensions.cs	Documents gRPC discovery setup.
dotnet/​src/​Microsoft.Agents.AI.A2A/​Extensions/​A2AAgentCardExtensions.cs	Documents registration and client ownership.
dotnet/​src/​Microsoft.Agents.AI.A2A/​A2AAgent.cs	Updates supported-response and direct-client documentation.
dotnet/​samples/​02-agents/​A2A/​README.md	Adds gRPC to the sample listing.
dotnet/​samples/​02-agents/​A2A/​A2AAgent_ProtocolSelection/​README.md	Explains protocol selection and gRPC setup.
dotnet/​samples/​02-agents/​A2A/​A2AAgent_ProtocolSelection/​Program.cs	Implements binding selection, registration, and disposal.
dotnet/​samples/​02-agents/​A2A/​A2AAgent_ProtocolSelection/​A2AAgent_ProtocolSelection.csproj	References the gRPC SDK package.
dotnet/​Directory.Packages.props	Pins the gRPC SDK package version.

_{Review effort: Balanced}

[github-actions]

MAF Automated Review — Iteration 1

Result: No findings
Scope: full PR (1 commit(s)): b43d25322df5
Model: gpt-5.6-sol

Overview

The change adds optional gRPC selection to the existing A2A protocol sample while keeping the framework package isolated from gRPC dependencies. Explicit startup registration, strict single-binding selection, caller-owned client disposal, existing protocol-selection tests, and the pinned SDK's case-insensitive factory behavior prevent a publishable correctness, architectural, or security concern.

Reviewed the supplied pull-request change set across correctness, security/reliability, architecture, and failure behavior.
No publishable findings remained after source verification for this scope.