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Visual Studio 2026 18.5.0 lets GitHub Copilot load Agent Skills from .github/skills, .claude/skills, and ~/.copilot/skills. Reusable SKILL.md instruction packs travel with your repo.

.NET 11 Preview 3 teaches RyuJIT to eliminate redundant bounds checks on consecutive index-from-end access and on i + constant < length patterns, cutting branch pressure in tight loops.

.NET 11 Preview 3 adds RegexOptions.AnyNewLine so ^, $, \Z, and . recognize every Unicode newline sequence, including \r\n, NEL, LS, and PS, with \r\n treated as one atomic break.

Aspire 13.2 ships an --isolated flag that gives each aspire run its own random ports and secrets store. It unblocks multi-checkout work, agent worktrees, and integration tests that need a live AppHost.

dotnet run -e in .NET 11 Preview 3 passes environment variables straight from the CLI and surfaces them as MSBuild RuntimeEnvironmentVariable items.

.NET 11 Preview 3 teaches dotnet sln to create, add, remove, and list projects in .slnf solution filters, so large mono-repos can load a subset without opening Visual Studio.

dotnet watch gains Aspire app host integration, automatic relaunch after crashes, and fixed Ctrl+C handling for Windows desktop apps in .NET 11 Preview 3.

EF Core 11 Preview 3 removes redundant to-one joins from split queries and drops unneeded ORDER BY keys. One reported scenario got 29% faster, another 22%. Here is what the SQL now looks like.

.NET 11 Preview 3 finishes the naming-policy story in System.Text.Json: JsonNamingPolicy.PascalCase, a member-level [JsonNamingPolicy] attribute, and a type-level [JsonIgnore] default for cleaner DTOs.

ASP.NET Core in .NET 11 Preview 3 teaches the Virtualize component to measure items at runtime, fixing the spacing and scroll jitter that uniform-height assumptions caused.