architecture
This skill guides .NET architects and senior developers through structural decisions for new or evolving systems by evaluating business capability boundaries and change frequency before selecting patterns like clean architecture, vertical slices, DDD, CQRS, or microservices. Use it when establishing architecture for greenfield projects, reviewing existing layer and domain boundaries, or deciding whether to migrate from monolith to distributed systems, with validation that chosen patterns reduce complexity rather than add ceremony.
git clone --depth 1 https://github.com/managedcode/dotnet-skills /tmp/architecture && cp -r /tmp/architecture/catalog/Platform/Architecture/skills/architecture ~/.claude/skills/architectureSKILL.md
# .NET Architecture ## Trigger On - choosing architecture for a new or evolving .NET system - reviewing layer boundaries, domain boundaries, or service decomposition - deciding whether clean architecture, vertical slices, CQRS, or microservices are justified ## Workflow 1. Start from business capability boundaries and change frequency, not from a preferred diagram style. 2. Use simple modular monolith patterns by default, and move to microservices only when team autonomy, scale, or deployment boundaries justify the added operational cost. 3. Apply DDD and CQRS where business rules are genuinely complex; avoid forcing aggregates and command pipelines into CRUD-heavy code with no payoff. 4. Keep dependencies flowing inward when using clean architecture, but avoid creating extra projects that add ceremony without ownership clarity. 5. Make integration boundaries explicit: contracts, storage ownership, messaging, consistency model, and observability expectations. 6. Use `aspire` when local orchestration, service discovery, and developer observability are part of the architecture story. ## Deliver - an architecture direction that matches system complexity - clear project and dependency boundaries - migration notes or tradeoffs when changing an existing structure ## Validate - the proposed structure reduces rather than increases accidental complexity - data ownership and integration paths are explicit - the architecture is testable and operable, not just diagram-friendly ## References - [references/patterns.md](references/patterns.md) - detailed implementations of Clean Architecture, Vertical Slices, DDD, CQRS, Modular Monolith, and Microservices with C# 12+ examples - [references/anti-patterns.md](references/anti-patterns.md) - common architectural mistakes including over-abstraction, anemic domain models, premature microservices, and cargo cult patterns
Build, debug, modernize, or review ASP.NET Core applications with correct hosting, middleware, security, configuration, logging, and deployment patterns on current .NET. USE FOR: working on ASP.NET Core apps, services, or middleware; changing auth, routing, configuration, hosting, or deployment behavior; deciding between ASP.NET Core sub-stacks. DO NOT USE FOR: unrelated stacks; generic tasks that do not need this specific guidance. INVOKES: inspect the repository context, edit targeted files, and run relevant build, test, lint, or validation commands when changes are made.
Build, upgrade, and operate .NET Aspire 13.3.x application hosts with current CLI, AppHost, ServiceDefaults, integrations, dashboard, testing, and Azure deployment patterns for distributed apps. USE FOR: Aspire.AppHost.Sdk, Aspire.Hosting.*, DistributedApplication.CreateBuilder, WithReference, WaitFor, AddProject, AddRedis, AddPostgres, aspire run, aspire init, aspire. DO NOT USE FOR: unrelated stacks; generic tasks that do not need this specific guidance. INVOKES: inspect the repository context, edit targeted files, and run relevant build, test, lint, or validation commands when changes are made.
Build, review, or migrate Azure Functions in .NET with correct execution model, isolated worker setup, bindings, DI, and Durable Functions patterns. USE FOR: working on Azure Functions in .NET; migrating from the in-process model to the isolated worker model; adding Durable Functions, bindings, or host configuration. DO NOT USE FOR: unrelated stacks; generic tasks that do not need this specific guidance. INVOKES: inspect the repository context, edit targeted files, and run relevant build, test, lint, or validation commands when changes are made.
Build and review Blazor applications across server, WebAssembly, web app, and hybrid scenarios with correct component design, state flow, rendering, and hosting choices. USE FOR: building interactive web UIs with C# instead of JavaScript; choosing between Server, WebAssembly, or Auto render modes; designing component hierarchies and state. DO NOT USE FOR: unrelated stacks; generic tasks that do not need this specific guidance. INVOKES: inspect the repository context, edit targeted files, and run relevant build, test, lint, or validation commands when changes are made.
Maintain or migrate EF6-based applications with realistic guidance on what to keep, what to modernize, and when EF Core is or is not the right next step. USE FOR: EF6 codebases; runtime versus ORM migration decisions; EDMX, code-first, ObjectContext, and legacy data-access review. DO NOT USE FOR: unrelated stacks; generic tasks that do not need this specific guidance. INVOKES: inspect the repository context, edit targeted files, and run relevant build, test, lint, or validation commands when changes are made.
Design, tune, or review EF Core data access with proper modeling, migrations, query translation, performance, and lifetime management for modern .NET applications. USE FOR: DbContext, migrations, model configuration, EF queries, tracking, loading, performance, transactions, and EF6 migration decisions. DO NOT USE FOR: unrelated stacks; generic tasks that do not need this specific guidance. INVOKES: inspect the repository context, edit targeted files, and run relevant build, test, lint, or validation commands when changes are made.
Build, review, or migrate .NET MAUI applications across Android, iOS, macOS, and Windows with correct cross-platform UI, platform integration, and native packaging assumptions. USE FOR: working on cross-platform mobile or desktop UI in .NET MAUI; integrating device capabilities, navigation, or platform-specific code; migrating Xamarin.Forms or aligning. DO NOT USE FOR: unrelated stacks; generic tasks that do not need this specific guidance. INVOKES: inspect the repository context, edit targeted files, and run relevant build, test, lint, or validation commands when changes are made.
Use ML.NET to train, evaluate, or integrate machine-learning models into .NET applications with realistic data preparation, inference, and deployment expectations. USE FOR: ML.NET integration; local model training or retraining; inference pipelines, model loading, evaluation, and deployment review. DO NOT USE FOR: unrelated stacks; generic tasks that do not need this specific guidance. INVOKES: inspect the repository context, edit targeted files, and run relevant build, test, lint, or validation commands when changes are made.