Browse All .NET Content (237)

Dmitrii Korolev explains how C# 15 union types and closed class hierarchies behave in ASP.NET Core when serialized with System.Text.Json, including what works in Minimal APIs, MVC, SignalR, Blazor, and OpenAPI, plus the trade-offs around discriminator-free JSON and ambiguous payloads.

Visual Studio Code announces a new “VS Code pet” coding companion that you can trigger from GitHub Copilot Chat in VS Code using the /vscode-pet command, and invites the community to submit name ideas during a one-week window.

Authorised Territory demonstrates how to build domain-specific AI agent evaluators in .NET using Microsoft Agent Framework connected to a local Ollama model, then run automated checks against the agent’s responses to validate both content and output structure.

Allison announces CodeQL 2.27.0, highlighting native Linux ARM64 support, improvements to GitHub code scanning default setup, and multiple query and framework-modeling updates that improve vulnerability detection across C#, Java/Kotlin, C/C++, and Rust projects.

Jon Galloway, Daniel Roth, Mads Torgersen, Chet Husk, and Drew Noakes host a .NET Unboxed release party focused on .NET 11 Release Candidate 1, highlighting favorite features and what developers should pay attention to as .NET 11 approaches release.

.NET Team announces .NET 11 Release Candidate 1, highlighting runtime, SDK, MSBuild, NuGet, and language updates, plus ASP.NET Core, .NET MAUI, and Windows Forms improvements. The post links to detailed release notes and includes download and tooling guidance for trying RC1 in production.

Javier Lozano, Chris Sfanos, and Jon Galloway announce that the call for presenters is open for .NET Conf 2026 Community Days, with session proposals accepted from September 8 through October 6, 2026, and a separate volunteer opportunity for helping run the event.

Rahul Bhandari and Tara Overfield recap the September 2026 servicing releases for .NET and .NET Framework, highlighting security and non-security fixes, the list of addressed CVEs, and where to find release notes, installers, container images, Linux packages, and known issues for supported versions.

Justin Yoo walks through a practical profiling workflow for distributed .NET apps, showing how to identify which process owns a slow user interaction, use Visual Studio CPU profiling to rule out CPU-bound work, and then measure hidden async waiting that doesn’t show up in CPU samples.

Visual Studio Code highlights how to get a new set of file icons in VS Code quickly, pointing viewers to the Catppuccin icon theme link for a fast editor refresh.

Maddy Montaquila explains how a “Aspire-ified” .NET app can give a coding agent more context and control, including a single command to start containers, processes, and the debugger, plus the ability to manage resources and view logs from one place.

This week's .NET roundup connects two practical threads: testing under real deployment constraints and building agent-style workflows you can run in production. MSTest 4.4 brings Native AOT test publishing so you can catch trimming and reflection issues earlier, while new .NET agent building blocks (Copilot SDK, lightweight harnesses, and MCP servers on Azure Functions) push tool calling and orchestration toward repeatable, auditable runs. On the day-to-day side, Visual Studio 2026 and VS Code updates focus on reducing context mistakes (scoped settings, worktrees, clearer Copilot context), and ecosystem updates like CodeQL 2.26.4 and Azure SDK releases highlight where CI and dependencies can shift under your feet.

Authorised Territory demonstrates how to build an AI agent with the .NET Microsoft Agent Framework using a local Ollama model, then evaluate the agent locally with built-in checks to confirm response quality and that required tools were actually invoked.

Justin Bettencourt’s August 2026 Azure SDK roundup highlights new and updated client libraries across .NET, Java, JavaScript/TypeScript, Python, Go, and more, including Document Translation 2.0.0, Azure Storage Blobs 12.30.0-beta.1, and the first stable release of Azure AI Discovery.

James Montemagno and Matt Soucoup run a beginner-friendly livestream on the GitHub Copilot SDK for .NET, focusing on how to embed Copilot’s agent runtime into your own apps for multi-turn conversations, tool calling, streaming responses, and MCP-based extensibility.

Amaury Levé explains how MSTest 4.4 uses source generation to make test projects publishable and runnable as Native AOT executables, so your tests exercise the same trimming and reflection constraints as the app you deploy.

Allison summarizes what’s new in CodeQL 2.26.4 for GitHub code scanning, including language support updates and query accuracy improvements that affect security detections across C#, Java/Kotlin, and GitHub Actions workflows.

dotnet demonstrates how to stand up an agent “harness” in C# using a single AsHarnessAgent call, then incrementally add tool calling, web search, and planning so a vague request becomes a tracked, step-by-step execution loop.

Visual Studio Code shows how to use the Command Palette to navigate faster in VS Code, including opening recent files, jumping to symbols in the current file, grouping symbols by type, and searching for symbols across the entire workspace.

The Visual Studio Code Team shares Insiders updates for VS Code 1.137, focusing on Copilot-related workflow improvements such as clearer model token limits, better context handling when pasting GitHub issue/PR links, and updated new-session composer controls.

Mads Kristensen shows how to give each Visual Studio solution its own color theme so multiple IDE instances are easier to tell apart. He also explains the new scoped settings model in Visual Studio 2026, where solution-level settings are stored in a JSON file you can optionally commit to source control for consistent team setup.

Jonah Andersson explains how to take AI agents from prototype to production by building MCP servers on Azure Functions, using .NET to expose tools that agents can discover and invoke at runtime. The session uses a DevOps CI/CD scenario where agents detect deployment issues, diagnose failures, and create rollback PRs in Azure DevOps.

Aaron Powell walks through reviewing GitHub pull requests directly inside Visual Studio, from opening the PR list and navigating diffs to leaving inline comments, approving, and merging. He also shows how to bring GitHub Copilot into the review by adding a PR as chat context using the UI or the #pullrequest: command.

Visual Studio Code shares a trailer for “The Story of VS Code,” a documentary-style look at how VS Code evolved from early web editor experiments into a widely used open-source editor and extension ecosystem, and how the team is adapting as AI changes what a code editor can be.

Andrew Lock digs into .NET 11 preview 7’s new union types and closed class hierarchies, focusing on where System.Text.Json serialization and deserialization fall over. He shows the default behavior, the exceptions you’ll hit with inferred polymorphism, and the workarounds using JsonDerivedType and custom union type classifiers.

Authorised Territory shows how to use Git worktrees in the Visual Studio 2026 August update to pause half-finished work without stashing, by creating a separate working directory tied to a new branch while keeping current changes intact.

Microsoft Developer shares a quick developer news roundup covering Bring Your Own Model entering preview in Visual Studio, updates to the model router in Microsoft Foundry Models (including region expansion and refreshed model pool), and the announced date for .NET Conf 2026.

This week in .NET, the tooling story centered on agentic workflows becoming a first-class part of everyday development, with Visual Studio 2026 expanding Copilot into configurable, team-managed agents and adding practical Git upgrades like worktrees and deeper submodule support. Model choice and tool connectivity also tightened up as Bring Your Own Model (BYOM), Model Context Protocol (MCP), and the Microsoft Agent Framework converged into a clearer path from prototype agents to production hosts with observability and governance. On the platform side, C# 15 preview discussions focused on union types (plus closed hierarchies and safety-related changes), while debugging and testing workflows in both Visual Studio and VS Code moved toward tighter loops for reproducing, fixing, and validating failures.

Amanda Silver reflects on major technical shifts behind Visual Studio and Visual Studio Code, focusing on VS Code’s open-source architecture and extension ecosystem, and how GitHub Copilot and AI-assisted coding changed what developers expect from an editor and its connected cloud services.

Amanda Silver reflects on how Visual Studio Code grew from an open source editor into a platform shaped by its extension ecosystem, and how GitHub Copilot changed expectations for developer tools by bringing AI-powered coding assistance into everyday workflows.

Allison summarizes the August 2026 update for GitHub Copilot in Visual Studio, including organization-level custom agents, usage visibility, model selection and “thinking effort” controls, and a Git agent that can review uncommitted changes or commits before opening a pull request.

Allison summarizes the August 24 weekly GitHub Copilot updates, covering shared agent sessions in Slack and Microsoft Teams, the Copilot app’s new Customize experience (including MCP servers and plugins), Copilot CLI session and permission defaults, and IDE improvements across VS Code, JetBrains, and Visual Studio.

Visual Studio Code shares a quick tip focused on staying in the editor flow by creating new files quickly while you work.

Learn Microsoft AI explains how edges in Microsoft Agent Framework workflows control message routing between executors, including conditional paths for dynamic branching based on message content or execution results.

Sam Basu explains how Uno Platform built two MCP servers in C#—one for documentation grounding and one for driving a live app—so AI agents can look up accurate APIs, run and inspect a cross-platform .NET UI, and validate changes instead of just generating code.

Mads Torgersen introduces union types coming in C# 15, showing how they let you model a closed set of unrelated types, create union values, and switch over them with full strong typing. He also points to a preview compiler you can try in Visual Studio and VS Code.

Mads Torgersen introduces union types coming in C# 15, showing how they let you model a closed set of unrelated types, create union values, and switch over them with full strong typing, with notes on trying the feature today via preview tooling in Visual Studio and VS Code.

Wes Steyn shows how to take a Microsoft Agent Framework “claw” from a working local prototype to something you can actually run for other people: one shared agent factory feeding multiple hosts, with OpenTelemetry observability, Purview governance, Foundry hosting, and repeatable evals for quality and regression checks.

James Rempt recaps VSLive! @ Microsoft HQ 2026 with the main themes developers discussed—AI across the workflow, GitHub Copilot inside Visual Studio, and practical .NET modernization—and links to recorded sessions on performance, ASP.NET Core/Blazor, C#, and an MCP-based SQL agent scenario.

Visual Studio Code shares a quick tip on adjusting editor and terminal font sizes independently, so you can make text larger or smaller without zooming the entire VS Code interface.