[SergeyMenshykh]

Motivation

Update the .NET integration to the latest published A2A SDK, 1.0.0-preview4.

Description

• Update A2A, A2A.AspNetCore, and A2A.Grpc from 1.0.0-preview3 to 1.0.0-preview4.
• Raise only the shared dependency versions required by the new SDK and its transitive dependencies.
• Pass the explicit request-context argument in direct server calls.
• Use RequestContext.IncomingMessage to preserve support for requests without an incoming message.

AI assistance: Copilot assisted with the dependency update, compatibility changes, and PR description.

Related Issue

N/A - dependency upgrade with the compatibility changes required by the new SDK.

[Copilot]

🟢 Approval recommended

No active review issues are reported for the .NET A2A SDK compatibility update.

No open issues 🎉

What changed in this PR

Updates the .NET A2A integration to SDK 1.0.0-preview4, with compatibility changes that preserve handling of requests without an incoming message.

Changes:

• Upgrade the three A2A packages and required shared dependencies.
• Use RequestContext.IncomingMessage for nullable message access.
• Pass explicit request-context arguments in direct server calls in unit tests.

File	Description
dotnet/​tests/​Microsoft.Agents.AI.Hosting.A2A.UnitTests/​A2AServerServiceCollectionExtensionsTests.cs	Adapt server calls to the updated SDK signatures.
dotnet/​src/​Microsoft.Agents.AI.Hosting.A2A/​A2AAgentHandler.cs	Use nullable incoming-message access for validation and conversion.
dotnet/​Directory.Packages.props	Upgrade A2A packages and supporting dependency versions.

_{Review effort: Balanced}

[github-actions]

MAF Automated Review — Iteration 1

Result: No findings
Scope: full PR (1 commit(s)): a67e7db1e4f1
Model: gpt-5.6-sol

Overview

This PR upgrades the A2A SDK packages and their required shared dependencies together, adapts direct server calls to the new request-context parameter, and uses IncomingMessage where preview4 permits proactive execution without an inbound message. The preview4 package contract supports that migration, central package pinning keeps the dependency graph aligned, and the relevant client and hosting test suites passed across the exercised target frameworks. No publishable Critical, High, or Medium defect was established.

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.