add-endpoint

name	add-endpoint
description	Add a new Minimal API endpoint following this solution's conventions. Use when the user asks to add a route, endpoint, or new API operation (GET/POST/PUT/DELETE).
argument-hint	[HTTP-verb] [route] [short description]

Add a Minimal API Endpoint

Task: implement $ARGUMENTS end to end.

1. Read the neighborhood first. Open the existing endpoint group for this resource (or the closest one) and mirror its structure exactly: MapGroup usage, TypedResults unions, DTO records, DI parameters.
2. Define contracts. Request/response DTOs as record types. Never expose EF entities.
3. Wire the data path. If a needed repository/service method doesn't exist, add the interface method in Core, implement it in Data with async EF Core + CancellationToken, and register it if new.
4. Implement the endpoint with:
   • TypedResults union return type
   • Input validation before any database call, returning ValidationProblem on failure
   • Correct status codes (201 + Location on create via CreatedAtRoute/Created, 204 on delete, 404 on missing)
   • CancellationToken threaded through
   • Structured logging for failures only (don't log every request)
5. Write tests in the Tests project: at least one happy path and one failure path per endpoint, named MethodName_Scenario_ExpectedResult. Use WebApplicationFactory<Program> for integration coverage.
6. Verify. dotnet build --nologo then dotnet test --nologo --filter scoped to the new tests. Report results.
7. Summarize the new route, its status codes, and any follow-ups (auth, pagination, caching) you deliberately left out.