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aspnet-core

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Build and review ASP.NET Core apps using current official .NET guidance.

What it does

Pick the right ASP.NET Core app model and assemble the host and request pipeline the way Microsoft documents today. Loads only the references the task needs: stack selection, Program.cs and middleware, one UI/API reference, plus cross-cutting topics like data, security, SignalR/gRPC, testing, and upgrades. Targets the latest stable ASP.NET Core and prefers WebApplicationBuilder, built-in DI, ProblemDetails, OpenAPI, health checks, and rate limiting over third-party alternatives.

When to use it

  • Starting a new ASP.NET Core app and choosing between Blazor, Razor Pages, MVC, or Minimal APIs
  • Reviewing or refactoring Program.cs, middleware, and DI setup
  • Adding cross-cutting concerns like auth, EF Core, SignalR, or testing
  • Migrating or upgrading between ASP.NET Core major versions

The skill document

ASP.NET Core

Overview

Choose the right ASP.NET Core application model, compose the host and request pipeline correctly, and implement features in the framework style Microsoft documents today.

Load the smallest set of references that fits the task. Do not load every reference by default.

Workflow

  1. Confirm the target framework, SDK, and current app model.
  2. Open references/stack-selection.md first for new apps or major refactors.
  3. Open references/program-and-pipeline.md next for Program.cs, DI, configuration, middleware, routing, logging, and static assets.
  4. Open exactly one primary app-model reference:
    • references/ui-blazor.md
    • references/ui-razor-pages.md
    • references/ui-mvc.md
    • references/apis-minimal-and-controllers.md
  5. Add cross-cutting references only as needed:
    • references/data-state-and-services.md
    • references/security-and-identity.md
    • references/realtime-grpc-and-background-work.md
    • references/testing-performance-and-operations.md
  6. Open references/versioning-and-upgrades.md before introducing new platform APIs into an older solution or when migrating between major versions.
  7. Use references/source-map.md when you need the Microsoft Learn section that corresponds to a task not already covered by the focused references.

Default Operating Assumptions

  • Prefer the latest stable ASP.NET Core and .NET unless the repository or user request pins an older target.
  • As of March 2026, prefer .NET 10 / ASP.NET Core 10 for new production work. Treat ASP.NET Core 11 as preview unless the user explicitly asks for preview features.
  • Prefer WebApplicationBuilder and WebApplication. Avoid older Startup and WebHost patterns unless the codebase already uses them or the task is migration.
  • Prefer built-in DI, options/configuration, logging, ProblemDetails, OpenAPI, health checks, rate limiting, output caching, and Identity before adding third-party infrastructure.
  • Keep feature slices cohesive so the page, component, endpoint, controller, validation, service, data access, and tests are easy to trace.
  • Respect the existing app model. Do not rewrite Razor Pages to MVC or controllers to Minimal APIs without a clear reason.

Reference Guide

  • references/_sections.md: Quick index and reading order.
  • references/stack-selection.md: Choose the right ASP.NET Core application model and template.
  • references/program-and-pipeline.md: Structure Program.cs, services, middleware, routing, configuration, logging, and static assets.
  • references/ui-blazor.md: Build Blazor Web Apps, choose render modes, and use components, forms, and JS interop correctly.
  • references/ui-razor-pages.md: Build page-focused server-rendered apps with handlers, model binding, and conventions.
  • references/ui-mvc.md: Build controller/view applications with clear separation of concerns.
  • references/apis-minimal-and-controllers.md: Build HTTP APIs with Minimal APIs or controllers, including validation and response patterns.
  • references/data-state-and-services.md: Use EF Core, DbContext, options, IHttpClientFactory, session, temp data, and app state responsibly.
  • references/security-and-identity.md: Apply authentication, authorization, Identity, secrets, data protection, CORS, CSRF, and HTTPS guidance.
  • references/realtime-grpc-and-background-work.md: Use SignalR, gRPC, and hosted services.
  • references/testing-performance-and-operations.md: Add integration tests, browser tests, caching, compression, health checks, rate limits, and deployment concerns.
  • references/versioning-and-upgrades.md: Handle target frameworks, breaking changes, obsolete APIs, and migrations.
  • references/source-map.md: Map the official ASP.NET Core documentation tree to the references in this skill.

Execution Notes

  • When generating new code, start from the correct dotnet new template and keep the generated structure recognizable.
  • When editing an existing solution, follow the solution's conventions first and use these references to avoid framework misuse or outdated patterns.
  • When a task mentions "latest", verify the feature on Microsoft Learn or the ASP.NET Core docs repo before relying on memory.

Questions people ask

Which ASP.NET Core version does this target?
The skill assumes the latest stable ASP.NET Core and prefers .NET 10 / ASP.NET Core 10 for new production work as of March 2026, treating ASP.NET Core 11 as preview unless the user asks for it.
Does it rewrite my existing app model?
No. The skill respects the existing app model and will not rewrite Razor Pages to MVC or controllers to Minimal APIs without a clear reason.
How does it handle older solutions?
For older solutions it opens the versioning and upgrades reference before introducing new platform APIs, and avoids newer patterns like WebApplicationBuilder when the codebase still uses Startup or WebHost unless the task is migration.

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