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.
7 daily senior rules
Rule 12: IOptionsSnapshot Over Raw Config
Sun 27 Sep
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.
Rule 11: Rethrow, Don't throw ex
Sat 26 Sep
throw ex resets the stack trace. throw preserves it. Cursor gets this wrong about 40 percent of the time when generating catch blocks. Rewrite any naked throw ex to throw unless the exception has been explicitly wrapped.
Rule 10: AsNoTracking for Reads
Fri 25 Sep
Every read-only EF Core query should call AsNoTracking. Add a rule that recognises query methods returning DTOs (not entities) and inserts the call. Cursor never does this by default and your read perf degrades silently across releases.
Rule 9: Scoped Capture in Singleton
Thu 24 Sep
The single most expensive .NET runtime bug: a Singleton holding a Scoped service. Cursor cheerfully writes this without warning. Audit constructor parameters of any class registered as Singleton — if any are typically Scoped (DbContext, repositories, MediatR sender), flag it before merge.
Rule 8: CancellationToken Propagation
Wed 23 Sep
Every async method in your codebase should accept and forward a CancellationToken. Make it a rule that any new async signature without one is flagged. Stops the AI from quietly losing cancellation half-way down a call chain.
Rule 7: IHttpClientFactory Discipline
Tue 22 Sep
Refuse new HttpClient() in any generated code. Force Cursor to inject IHttpClientFactory or a typed client. The classic socket-exhaustion bug is exactly the kind of footgun an AI hands you without realising.
Rule 6: TimeProvider Injection
Mon 21 Sep
Never let Cursor hardcode DateTime.Now or DateTime.UtcNow in business logic. Inject TimeProvider (or your own IClock) instead. This makes time deterministic for tests and stops the AI reaching for static APIs whenever it generates time-aware code.
Try one rule before you trust the whole kit
The free arch-core-lite.mdc 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 £9.00.
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Free sample:
arch-core-lite.mdcon GitHub - Full kit (£9.00, one-time): Agentic Architect Kit
- Daily rules feed: https://agentic-architect.dev/blog/
Canonical home for everything in this digest: https://agentic-architect.dev/blog/.
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