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

Subclass ThemeExtension, register one instance per ThemeData through the extensions list, read it with Theme.of(context).extension<T>(), and write a real lerp so MaterialApp's AnimatedTheme interpolates your tokens during a light/dark switch. Covers colors, radii, shadows, text styles and booleans, the missing-extension crash, the copyWith trap that drops every other extension, and why you need == and hashCode, all verified with widget tests on Flutter 3.44.8.

Since Claude Code v2.1.295, a command or HTTP hook can set onFailure to "block" so a guard that crashes, times out, cannot start or prints invalid JSON stops the tool call instead of waving it through. Here is the config, what counts as a failure, the events where it does nothing, and the exit-0 trap no setting can catch.

AnimatedSwitcher only transitions when Widget.canUpdate says the new child is a different widget, so Text to Text with no key just updates in place. Here is the one-line fix, where the key has to sit, why UniqueKey is a trap, the slide-direction bug caused by a static transitionBuilder, and the layout jump from the default Stack, all verified with widget tests on Flutter 3.44.8.

Android kills backgrounded Flutter apps to reclaim memory, and when the user comes back every StatefulWidget starts from scratch. Here is how to opt in with restorationScopeId, RestorationMixin and Restorable properties, restore text fields, scroll offsets and pushed routes, write a custom RestorableValue, and test it all with restartAndRestore and adb, verified on Flutter 3.44.8 and an Android 16 emulator.

OpenTelemetry .NET 1.20.0, released on October 15, 2026, adds TracerProviderBuilder.ConfigureSampler. A library can now wrap the sampler the SDK resolved from SetSampler, OTEL_TRACES_SAMPLER, or the default, instead of silently overwriting it.

FlutterError.onError only sees errors thrown inside framework callbacks. Unawaited futures, timers, streams, and code after an await go somewhere else. Here is which handler catches which error, measured on Flutter 3.44.8, and the main() setup that catches all of them, including on web.

Use the en-IN culture or set NumberFormatInfo.NumberGroupSizes to [3, 2] to print 12,34,56,789 instead of 123,456,789 in C#. Measured on .NET 10 and .NET 11 RC1: how the array works, why CurrencyGroupSizes is separate, the invariant-globalization trap that silently prints Western grouping, and a lakh/crore words helper.

Claude Code v2.1.296 lets a subagent auto-compact earlier than the main conversation. Set autoCompactWindow in the subagent's frontmatter or --agents JSON as a plain integer from 100000 to 1000000, and watch out for the 200k parsing trap, the CLAUDE_CODE_AUTO_COMPACT_WINDOW override, and the --agent session mode where the field does nothing.

A broadcast StreamController drops every event that fired before you subscribed. Here is a dependency-free BehaviorSubject replacement built on Stream.multi, a replayLatest() extension for existing streams, the async* shortcut that silently loses events, and the StreamBuilder initialData detail, all verified on Dart 3.12.2.

Refit 16.4.0 adds an opt-in HttpRetryHandler that retries idempotent requests, honors Retry-After and provider-specific headers like x-ratelimit-reset and x-ms-retry-after-ms, and needs no Polly or resilience package.