Add custom exception-to-status-code mapping to GlobalErrorHandlingMiddleware

[perkops]

Summary

Add the ability to map custom exception types to specific HTTP status codes in GlobalErrorHandlingMiddleware. This enables domain-specific exceptions to be automatically translated to appropriate HTTP responses.

Changes

New Feature: Custom Exception Mapping

• Add MapException<T>(HttpStatusCode) fluent API to GlobalErrorHandlingOptions
• Add ExceptionMappingResolver for immutable, thread-safe status code resolution
• Support inheritance: derived exception types inherit base type mappings
• Custom mappings take precedence over built-in defaults
• Type-safe API using HttpStatusCode enum

Usage Example

app.UseGlobalErrorHandler(options =>
{
    options.MapException<OrderNotFoundException>(HttpStatusCode.NotFound);
    options.MapException<DuplicateResourceException>(HttpStatusCode.Conflict);

    // For exotic status codes not in HttpStatusCode enum
    options.MapException<TeapotException>((HttpStatusCode)StatusCodes.Status418ImATeapot);
});

Sample & Documentation

- Add GET /api/test/teapot endpoint demonstrating HTTP 418 response
- Add TeapotException as example custom exception
- Update README with custom exception mapping documentation

[Copilot]

Pull request overview

This PR adds a custom exception-to-status-code mapping feature to GlobalErrorHandlingMiddleware, enabling domain-specific exceptions to be automatically translated to appropriate HTTP responses. The implementation includes a fluent API, thread-safe resolver, and inheritance support.

• Introduces MapException<T> fluent API for custom exception mappings
• Implements ExceptionMappingResolver for immutable, thread-safe status code resolution
• Adds comprehensive test coverage and sample/documentation demonstrating HTTP 418 "I'm a teapot" response

Reviewed changes

Copilot reviewed 25 out of 25 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
test/Directory.Build.props	Updated test dependency package versions
test/Atc.Rest.MinimalApi.Tests/Middleware/GlobalErrorHandlingMiddlewareTests.cs	Added test cases for custom exception mapping, inheritance, precedence, and method chaining
test/Atc.Rest.MinimalApi.Tests/GlobalUsings.cs	Added System.Net and test exceptions namespace imports
test/Atc.Rest.MinimalApi.Tests/Exceptions/TeapotTestException.cs	Created test exception for demonstrating custom mapping
test/.editorconfig	Disabled CA1515 analyzer rule
src/Atc.Rest.MinimalApi/Options/GlobalErrorHandlingOptions.cs	Added MapException methods and BuildResolver for custom exception mappings
src/Atc.Rest.MinimalApi/Options/ExceptionMappingResolver.cs	Implemented immutable resolver with inheritance support for exception-to-status-code mapping
src/Atc.Rest.MinimalApi/Middleware/GlobalErrorHandlingMiddleware.cs	Refactored to use ExceptionMappingResolver instead of switch-based mapping
src/Atc.Rest.MinimalApi/GlobalUsings.cs	Added System.Collections.Frozen namespace
src/Atc.Rest.MinimalApi/Atc.Rest.MinimalApi.csproj	Updated package dependency versions
sample/test/Directory.Build.props	Updated sample test dependency package versions
sample/src/Demo.Web/Demo.Web.csproj	Updated sample web dependency package versions
sample/src/Demo.Domain/Demo.Domain.csproj	Updated sample domain dependency package versions
sample/src/Demo.AppHost/Demo.AppHost.csproj	Updated Aspire SDK version
sample/src/Demo.Api/GlobalUsings.cs	Added System.Net and exceptions namespace imports
sample/src/Demo.Api/Extensions/WebApplicationExtensions.cs	Demonstrated TeapotException custom mapping to HTTP 418
sample/src/Demo.Api/Demo.Api.csproj	Updated sample API dependency package versions
sample/src/Demo.Api.Contracts/GlobalUsings.cs	Added exceptions namespace import
sample/src/Demo.Api.Contracts/Exceptions/TeapotException.cs	Created sample exception for HTTP 418 demonstration
sample/src/Demo.Api.Contracts/EndpointDefinitions/TestEndpointDefinition.cs	Added /api/test/teapot endpoint demonstrating custom exception mapping
sample/src/Demo.Api.Contracts/EndpointDefinitions/SwaggerGroupNames.cs	Added Test group constant for Swagger organization
sample/src/Demo.Api.Contracts/Demo.Api.Contracts.csproj	Updated sample contracts dependency package versions
sample/Directory.Build.props	Updated sample code analyzer package versions
README.md	Added custom exception mapping documentation with usage examples and default mappings table
Directory.Build.props	Updated code analyzer package versions

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.