csharp

Tiered compilation lets the .NET JIT compile every method twice: once fast and unoptimized to get your app running, then again with full optimizations once the runtime knows a method is hot. Here is how tier 0, tier 1, on-stack replacement, and Dynamic PGO fit together, and how to observe and tune them.

IHostedService is the two-method interface (StartAsync/StopAsync) the .NET generic host calls on startup and graceful shutdown. Here is exactly what the contract promises, when to implement it directly, and the .NET 10 and 11 behavior changes that catch people out.

Trim-safe code is code the .NET trimmer can statically prove is reachable, so it survives when unused code is removed from a self-contained app. This is the practical guide: turn on the analyzer, drive every IL2xxx warning to zero, annotate reflection with DynamicallyAccessedMembers, propagate RequiresUnreferencedCode to public APIs, and replace unanalyzable patterns with source generators.

A step-by-step checklist for moving an existing Semantic Kernel 1.77 .NET app to Microsoft Agent Framework 1.13. Covers the Kernel-to-AIAgent rewrite, plugins-to-tools, thread-to-session, the KernelFunction compatibility bridge, DI changes, and the gotchas that bite mid-cutover.

CS9035 means a member marked required was not assigned. Set it in the object initializer, or add a constructor annotated with [SetsRequiredMembers] that assigns every required member.

Call AddProblemDetails with a CustomizeProblemDetails callback to reshape the 400 that built-in minimal API validation returns in ASP.NET Core 11: add a traceId, rewrite the title, switch 400 to 422, or take full control with a custom IProblemDetailsWriter.

A complete, working setup for JWT bearer authentication in an ASP.NET Core 11 minimal API: install the package, wire up AddAuthentication().AddJwtBearer(), issue a token, protect endpoints with RequireAuthorization, add role and claim policies, and test the whole thing with dotnet user-jwts.

Apply two independent global query filters to the same entity in EF Core 11: a soft-delete filter and a tenant filter, each named so you can disable one without the other via IgnoreQueryFilters.

A complete guide to IAsyncDisposable in C#: when to use await using, how to write DisposeAsync and DisposeAsyncCore correctly, and the stacking and ConfigureAwait gotchas that leak resources.

Thread a CancellationToken cleanly through every layer of an async call chain in .NET 11: last-parameter convention, default values, linked tokens, ASP.NET Core RequestAborted, and the CA2016 analyzer that catches the ones you drop.