Seven weekly Cursor rules for senior .NET engineers using AI-assisted coding

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The Agentic Architect blog published seven daily coding rules during the week ending September 20, 2026, targeting senior C#/.NET developers who use the Cursor AI editor. The rules cover best practices such as using MapGroup over bloated Controllers, enforcing FluentValidation on every MediatR request, and adopting structured logging templates instead of string interpolation. Other guidance includes isolating database logic in the Infrastructure layer, using Result objects instead of nulls for flow control, and manually adding OpenTelemetry activity spans since Cursor does not generate them automatically. The series also warns against treating ValueTask as a drop-in replacement for Task without verifying that a method is predominantly synchronous. A free sample Cursor rule file, arch-core-lite.mdc, is available on GitHub, with a full paid kit offered for a one-time fee of £9.00.

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