| name | async-hygiene |
| description | Find and fix async/await anti-patterns in C# code — blocking calls, async void, missing cancellation, fire-and-forget. Use when reviewing async code, diagnosing deadlocks or thread-pool starvation, or when the user asks about async correctness. |
Async/Await Hygiene Sweep
Scan the target scope (default: whole solution) for each anti-pattern, in this order, and fix with the standard remedy:
| Anti-pattern | Find | Fix |
|---|
| Sync-over-async | .Result, .Wait(), .GetAwaiter().GetResult() | Make the caller async and await |
async void | any non-event-handler | Return Task |
| Missing CancellationToken | async public methods without a token parameter | Add CancellationToken cancellationToken = default and thread it through |
| Fire-and-forget | unawaited Task-returning calls | Await, or route through a background service with error handling |
Task.Run in ASP.NET request path | Task.Run( in Api project | Remove — the request is already on a thread-pool thread |
| Async lambda passed to sync delegate | async lambda to Action<> | Change delegate type or restructure |
Unnecessary async/await wrapper | method whose only await is the final return | Return the Task directly (unless in a using/try) |
| Blocking I/O in async method | File.ReadAllText, Thread.Sleep inside async | Use async equivalents (ReadAllTextAsync, Task.Delay) |
Process: grep for each pattern → read the surrounding code (some hits are legitimate, e.g. Main, console tools) → fix true positives → dotnet build → report a table of what changed and any hits deliberately left alone with reasoning.
