legacy-aspnet
The legacy-aspnet skill provides guidance for maintaining and modernizing classic ASP.NET applications built on the .NET Framework, including Web Forms and older MVC versions. Use it when working directly with legacy ASP.NET codebases, reviewing IIS configuration and application lifecycle behavior, or planning incremental migration strategies toward ASP.NET Core while preserving business logic and system stability.
git clone --depth 1 https://github.com/managedcode/dotnet-skills /tmp/legacy-aspnet && cp -r /tmp/legacy-aspnet/catalog/Platform/Legacy-ASP.NET/skills/legacy-aspnet ~/.claude/skills/legacy-aspnetSKILL.md
# Legacy ASP.NET ## Trigger On - working in Web Forms, legacy MVC, or classic ASP.NET applications - reviewing old IIS-centric configuration and lifecycle behavior - planning migration toward ASP.NET Core without breaking core business flows ## Workflow 1. Treat classic ASP.NET as a distinct stack with different hosting, lifecycle, and configuration rules from ASP.NET Core. 2. Stabilize behavior first: routing, session, auth, server controls, configuration transforms, and deployment assumptions. 3. Plan modernization in seams: isolate domain and service logic, then move replaceable edges instead of rewriting the whole app at once. 4. Use `wcf` or `entity-framework6` when the legacy app depends on those subsystems rather than flattening them into generic web work. 5. Be careful with guidance copied from ASP.NET Core because middleware, DI, and hosting assumptions do not transfer directly. 6. Validate in an environment that resembles real IIS and configuration transforms. ## Deliver - practical maintenance guidance for classic ASP.NET - stabilized legacy behavior and modernization seams - a migration path that avoids unnecessary risk ## Validate - classic and Core guidance are not mixed - legacy runtime assumptions are preserved deliberately - migration steps are incremental and testable ## References - [Migration Paths](references/migration.md): strategies for migrating from ASP.NET to ASP.NET Core, including incremental migration, strangler fig pattern, and component-specific guidance - [Maintenance Patterns](references/patterns.md): stabilization and maintenance patterns for legacy ASP.NET code, including abstraction layers, testing seams, and deployment practices
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.