Daily notes on .NET, C#, EF Core, MAUI, Blazor, and Flutter - for developers who ship.

.NET 11.0.0 and SDK 11.0.100 shipped on November 10, 2026 as an STS release supported until November 14, 2028. The retarget steps, what C# 15 turns on by default, what is still preview, and the CPU baseline check to do first.

CS8620 on a params member inside a C# 14 extension block is a Roslyn bug in the .NET SDK 10.0.1xx band. Move to SDK 10.0.200+ or 11.0.100, or pass an array until you can.

flutter test never runs the Dart plugin registrant, so getTemporaryDirectory() hits the MethodChannel default and throws MissingPluginException. On a macOS, Windows or Linux host you can register the host implementation (PathProviderFoundation 2.6.0+ is FFI, not a channel), use a temp-dir PathProviderPlatform fake, or run integration_test on desktop. Checked on Flutter 3.44.8 with path_provider 2.1.6.

The Anthropic Python and TypeScript SDKs now emit OpenTelemetry spans on their own: register a tracer provider before the first call and every messages.create becomes an anthropic.messages.create CLIENT span with gen_ai.* token, model and stop-reason attributes. Content mode, conversation IDs, user.id baggage, linking to the Claude Platform's server-side spans, streaming and tool runner behavior, and the env-var override trap, checked against anthropic 2.8.0.

Microsoft Agent Framework for .NET 1.28.0 removes A2AServerRegistrationOptions.AgentRunMode, so hosted A2A agents always answer with a message, and replaces the id/name/description overloads on A2AAgent and AsAIAgent with A2AAgentOptions. Here is what breaks and how to migrate.

Kestrel on .NET 10 only speaks h2c on an endpoint set to HttpProtocols.Http2, and only to clients that use prior knowledge. Http1AndHttp2 without TLS silently falls back to HTTP/1.1, Upgrade: h2c is ignored, and nginx needs proxy_http_version 2 (1.29.4+, stable 1.30) or grpc_pass to talk HTTP/2 upstream. Checked with curl and HttpClient on ASP.NET Core 10.0.10.

Send diagnostics.previous_message_id on every Messages API call and Claude tells you which part of the prompt broke the cache: model_changed, system_changed, tools_changed or messages_changed, plus an estimate of the tokens you paid to rewrite. Request and response shapes, the pending and not-found states, streaming, a logging helper for anthropic 2.7.0, and the limits.

Give each singleton a memoized InitializeAsync that awaits its own dependencies, then await them all from IHostedLifecycleService.StartingAsync. Registration order stops mattering, Kestrel does not accept requests until init finishes, and a failure stops the host. Compared against init before app.Run, IHostedService.StartAsync, and a BackgroundService with a readiness check on ASP.NET Core 10.0.10.

Blazor has no nextTick(), but you can build one: a TaskCompletionSource completed in OnAfterRenderAsync. Here is why the @ref is null or stale right after you flip an @if, which common workarounds fail, and a NextRenderAsync helper verified on .NET 10 in both InteractiveServer and InteractiveWebAssembly.

Stop editing the tools array between turns. Append a role: system message with tool_addition and tool_removal blocks (beta inline-tools-2026-09-15) so a Claude agent gains, loses or re-versions tools while the cached prefix and preserved thinking stay valid. Placement rules, defer_loading, schema changes, error codes and model support.