The .NET Insider – Issue 26

.NET 11 Preview 6 delivers updates across the runtime, SDK, libraries, C#, ASP.NET Core, .NET MAUI, EF Core, F#, and container images. Highlights include extension indexers, built-in union support types, System.Text.Json support for C# unions, async validation, OpenAPI 3.2 by default, CSRF protection, SignalR improvements, enhanced testing tools, and faster Native AOT interface dispatch.

Agent Skills for .NET has graduated from experimental preview and now provides a stable API for production use with Microsoft Agent Framework. Developers can package reusable instructions, documents, and scripts as file-based, class-based, or code-defined skills. The release also includes human approval controls, skill filtering, caching, extensible sources, and support for controlled script execution helping teams distribute specialized agent capabilities without filling the context window unnecessarily.

With .NET 11 Preview 6, CoreCLR is now the only runtime offered for .NET MAUI applications targeting Android, iOS, and Mac Catalyst. The runtime transition is functionally complete, bringing mobile applications onto the same runtime used by ASP.NET Core, cloud services, and desktop .NET. Developers also gain improved debugging, Hot Reload progress, on-device diagnostics, and early foundations for NativeAOT on Android. Blazor WebAssembly remains on Mono.

Microsoft’s July servicing releases include important security and reliability fixes for supported .NET and .NET Framework versions. The update addresses multiple vulnerabilities affecting .NET 8, .NET 9, and .NET 10, alongside additional non-security improvements. The latest releases are .NET 10.0.10, .NET 9.0.18, and .NET 8.0.29. Teams running supported production workloads should review the release notes and update their environments promptly.

The GitHub Copilot app now provides an interactive upgrade canvas for modernizing .NET applications. The upgrade agent assesses the application, evaluates dependencies, creates a structured plan, generates implementation tasks, applies changes, and tracks build failures and results in one view. The same modernization workflow is also available through Visual Studio, Visual Studio Code, and the GitHub Copilot CLI.

Standard MCP tool calls work well for quick operations but can encounter client timeouts when workflows take minutes or involve several stages. This article demonstrates how Durable Functions can support long-running MCP tools through stateful execution, checkpointing, recovery, and automatic scaling. It provides a practical architecture for moving MCP servers beyond simple request-response tools and toward durable, asynchronous agent workflows.

Evaluating API-powered agent skills against production services can create costs, mutate live data, and produce inconsistent results. Waldek Mastykarz presents a lighter approach using Dev Proxy to intercept requests and return realistic, locally managed responses while the skill continues using its original production URLs. This creates repeatable evaluation scenarios without maintaining a complete mock server or changing the skill being tested.

Version 1.44 of the MSSQL extension improves SQL development inside Visual Studio Code. The release introduces preview support for centralized shortcut configuration, reusable quick queries, and customizable SQL commands. It also delivers a redesigned results grid with better performance, stronger state management, and additional column controls, including the ability to freeze, hide, and display columns.

Microsoft engineers explain how query decomposition can improve semantic search when users combine structured metadata with natural-language descriptions. The proposed approach extracts fields such as episode, scene, and shot into strict filters while sending the cleaned descriptive query to vector search. This hybrid retrieval strategy reduces false positives, prevents metadata from weakening embeddings, and produces more accurate results across large media-asset collections.

Eligible Visual Studio subscribers can access discounted Azure pricing for development and testing workloads. The benefit can help individuals and teams create realistic non-production environments for architecture experiments, performance testing, deployment validation, and AI or cloud-service exploration. The article explains how the offer can reduce the cost barrier associated with building and frequently recreating Azure development environments.