CLAUDE.md for C# and .NET: 13 Rules That Make AI Write Modern, Idiomatic Production Code

Ask Claude Code to "add an endpoint that returns paged orders for a customer" and the output compiles. It also ignores nullable warnings, hides an async void , blocks the thread pool with .Result , wraps everything in try/catch (Exception) , reaches for a static DbContext , and sprinkles IConfiguration["..."] strings like glitter. It runs fine on your laptop. It deadlocks in staging. C# in 2026 is not the C# the model was trained on. NRTs, records, pattern matching, minimal APIs, file-scoped nam