# This week in Cursor + .NET — 6 rules + 3 essays (week ending May 31, 2026) > Source: > Published: 2026-05-31 11:51:26+00:00 *Every weekday a single, opinionated rule for senior C#/.NET engineers using Cursor. Here's the full week in one read — canonical posts live on the Agentic Architect blog.* *Sat 30 May · .NET tooling* Cursor forgets your DI patterns, boundaries, and conventions every session. Here's a 4-rule framework that locks your architecture into the AI's long-term memory. *Sat 30 May · .NET tooling* Cursor AI generates N+1 queries, eager-loads entire databases, and skips AsNoTracking. Here's a rule-based guardrail system that catches 90% of EF Core mistakes before production. *Tue 26 May · .NET tooling* Senior .NET teams aren't picking - they're paying for both. The honest comparison, the pricing math, and the config that lets the two tools share state. *Sun 31 May* In-memory EF Core providers lie. Use WebApplicationFactory with Testcontainers (SQL Server, Postgres) for real integration coverage. Cursor defaults to UseInMemoryDatabase — it passes locally and ships the bug to production. Flag the in-memory provider in test projects. *Sat 30 May* Library code (non-ASP.NET) should ConfigureAwait false on every awaited Task. ASP.NET Core code should not. Cursor mixes the two contexts in the same solution. Detect the project type and enforce the right default. *Fri 29 May* async void is a deadlock and unhandled-exception trap everywhere except UI event handlers. The AI uses it routinely for "fire and forget" — wrong answer every time. Flag it on sight. *Thu 28 May* Value objects (Money, Address, Coordinates) should be records. Entities with identity (Order, Customer) should be classes with an Id. Cursor mixes these constantly. A rule that classifies based on the presence or absence of an identity property keeps the distinction honest. *Wed 27 May* Mark every class sealed unless inheritance is explicitly planned. Stops Cursor inventing accidental inheritance hierarchies "for flexibility." Small but measurable virtual-call perf wins too. *Mon 25 May* Business code should never call IConfiguration directly. Strongly-typed IOptions or IOptionsSnapshot bindings only. The AI loves to "just grab the config value" — refuse it and force a settings class with validation attributes. The free is one drop-in Cursor rule that ends the morning re-explanation ritual. Install in 60 seconds, see whether Cursor actually remembers your DI lifetimes, and decide for yourself whether the full kit is worth £19.99. `arch-core-lite.mdc` `arch-core-lite.mdc` on GitHubCanonical home for everything in this digest: [https://agenticstandardcontact-byte.github.io/agentic-architect/blog/](https://agenticstandardcontact-byte.github.io/agentic-architect/blog/).