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Found 507 Skills
Provides guidance on new System.Text.Json APIs introduced in .NET 11. It covers typed JsonTypeInfo access via GetTypeInfo<T> and TryGetTypeInfo<T> on JsonSerializerOptions, and the new JsonNamingPolicy.PascalCase static property. Use when serializing or deserializing JSON in .NET 11 applications and needing typed metadata access or PascalCase property naming.
Symbolicate .NET runtime frames in Apple platform .ips crash logs (iOS, tvOS, Mac Catalyst, macOS). Extracts UUIDs and addresses from the native backtrace, locates dSYM debug symbols, and runs atos to produce function names with source file and line numbers. Automatically downloads .dwarf symbols from the Microsoft symbol server using Mach-O UUIDs. USE FOR triaging a .NET MAUI or Mono app crash from an .ips file on any Apple platform, resolving native backtrace frames in libcoreclr or libmonosgen-2.0 to .NET runtime source code, retrieving .ips crash logs from a connected iOS device or iPhone, or investigating EXC_CRASH, EXC_BAD_ACCESS, SIGABRT, or SIGSEGV originating from the .NET runtime. DO NOT USE FOR pure Swift/Objective-C crashes with no .NET components, or Android tombstone files. INVOKES Symbolicate-Crash.ps1 script, atos, dwarfdump, idevicecrashreport.
Analyzes the variety and depth of assertions across .NET test suites. Use when the user asks to evaluate assertion quality, find shallow testing, identify assertion-free tests (no assertions or only trivial ones like Assert.IsNotNull), flag self-referential or tautological assertions (output equals input on identity/round-trip operations), measure assertion coverage diversity, or audit whether tests verify different facets of correctness. Produces metrics and actionable recommendations. Works with MSTest, xUnit, NUnit, TUnit. DO NOT USE FOR: writing new tests (use writing-mstest-tests), other anti-patterns like flakiness or duplication (use test-anti-patterns), or fixing assertions.
Performs pseudo-mutation analysis on .NET production code to find gaps in existing test suites. Use when the user asks to find weak tests, discover untested edge cases, check if tests would catch a bug, or evaluate test effectiveness through mutation-style reasoning. Analyzes production code for mutation points (boundary conditions, boolean flips, null returns, exception removal, arithmetic changes) and checks whether existing tests would detect each mutation. Works with MSTest, xUnit, NUnit, and TUnit. DO NOT USE FOR: writing new tests (use writing-mstest-tests), detecting test anti-patterns (use test-anti-patterns), measuring assertion diversity (use assertion-quality), or running actual mutation testing tools.
Guidance for implementing CollectionView in .NET MAUI apps — data display, layouts (list & grid), selection, grouping, scrolling, empty views, templates, incremental loading, swipe actions, and pull-to-refresh. USE FOR: "CollectionView", "list view", "grid layout", "data template", "item template", "grouping", "pull to refresh", "incremental loading", "swipe actions", "empty view", "selection mode", "scroll to item", displaying scrollable data, replacing ListView. DO NOT USE FOR: simple static layouts without scrollable data (use Grid or StackLayout), map pin lists (use Microsoft.Maui.Controls.Maps), table-based data entry forms, or non-MAUI list controls.
Guide for modernizing and migrating MSBuild project files to SDK-style format. Only activate in MSBuild/.NET build context. Use when encountering legacy .csproj/.vbproj files with verbose XML, packages.config, or AssemblyInfo.cs patterns. Covers legacy-to-SDK migration, removing boilerplate, PackageReference migration, and Directory.Build consolidation. Invoke when asked to modernize, migrate, or clean up project files.
Build .NET applications with WolverineFX for messaging, HTTP services, and event sourcing. Use when implementing command handlers, message handlers, HTTP endpoints with WolverineFx.HTTP, transactional outbox patterns, event sourcing with Marten, CQRS architectures, cascading messages, batch message processing, or configuring transports like RabbitMQ, Azure Service Bus, or Amazon SQS.
Diagnoses .NET Framework CLR activation issues using CLR activation logs (CLRLoad logs) produced by mscoree.dll. Use when: the shim picks the wrong runtime, fails to load any runtime, shows unexpected .NET 3.5 Feature-on-Demand (FOD) dialogs, unexpectedly does NOT show FOD dialogs, loads both v2 and v4 into the same process causing failures, or any time someone is wondering "what is happening with .NET Framework activation?"
Guidance for configuring dependency injection in .NET MAUI apps — service registration in MauiProgram.cs, lifetime selection (Singleton / Transient / Scoped), constructor injection, Shell navigation auto-resolution, platform-specific registrations, and testability patterns. USE FOR: "dependency injection", "DI setup", "AddSingleton", "AddTransient", "AddScoped", "service registration", "constructor injection", "IServiceProvider", "MauiProgram DI", "register services", "BindingContext injection". DO NOT USE FOR: data binding (use maui-data-binding), Shell route configuration (use maui-shell-navigation), unit-test mocking frameworks (use standard xUnit and NSubstitute patterns).
Guide for diagnosing and improving MSBuild project evaluation performance. Only activate in MSBuild/.NET build context. Use when builds are slow before any compilation starts, when evaluation time is high in binlog analysis, or when dealing with expensive glob patterns and deep import chains. Covers evaluation phases, glob optimization, import chain analysis, and /pp preprocessing.
Test C# MCP servers at multiple levels: unit tests for individual tools and integration tests using the MCP client SDK. USE FOR: unit testing MCP tool methods, integration testing with in-memory MCP client/server, end-to-end testing via MCP protocol, testing HTTP MCP servers with WebApplicationFactory, mocking dependencies in tool tests, creating evaluations for MCP servers, writing eval questions, measuring tool quality. DO NOT USE FOR: testing MCP clients (this is server testing only), load or performance testing, testing non-.NET MCP servers, debugging server issues (use mcp-csharp-debug).
Guide for theming .NET MAUI apps — light/dark mode via AppThemeBinding, ResourceDictionary theme switching, DynamicResource bindings, system theme detection, and user theme preferences. Use when: "dark mode", "light mode", "theming", "AppThemeBinding", "theme switching", "ResourceDictionary theme", "dynamic resources", "system theme detection", "color scheme", "app theme", "DynamicResource". Do not use for: localization or language switching (see .NET MAUI localization documentation), accessibility visual adjustments (see .NET MAUI accessibility documentation), app icons or splash screens (see .NET MAUI app icons documentation), or Bootstrap-style class theming (see Plugin.Maui.BootstrapTheme NuGet package).