.NET solution and project structure conventions. Covers .slnx format, Directory.Build.props, Directory.Packages.props for central package management, global usings, and naming conventions. Load this skill when setting up a new solution, adding projects, configuring build properties, or when the user

Project Structure Core Principles 1. Central package management — Use Directory.Packages.props to manage NuGet package versions in one place. No version numbers in individual .csproj files. 2. Shared build properties — Use Directory.Build.props for common settings (target framework, nullable, implicit usings). Don't repeat in every project. 3. .slnx for solutions — The new XML based solution format is cleaner and more merge friendly than the legacy .sln format. 4. src/tests separation — Source projects in src/ , test projects in tests/ . Clear boundary. Patterns Solution Layout Directory.Build.props Directory.Packages.props (Central Package Management) Project File (.csproj) with Central Package Management global.json (SDK Pinning) .slnx Solution Format Naming Conventions Element Convention Example Solution CompanyName.AppName or AppName MyApp.slnx Project AppName.Layer MyApp.Api , MyApp.Domain Namespace Matches folder path MyApp.Api.Features.Orders Feature folder PascalCase, plural Features/Orders/ Test project ProjectName.Tests MyApp.Api.Tests Anti patterns Don't Scatter Package Versions Don't Repeat Build Properties Don't Mix Source and Test Projects Decision Guide Scenario Recommendation New solution .slnx format Package version management Directory.Packages.props (central) Shared build settings Directory.Build.props SDK version pinning global.json Common using directives Global usings in Directory.Build.props Small API (1 2 devs) Single project ( MyApp.Api ) Medium API (3 5 devs) 2 3 projects ( Api , Domain , Infrastructure ) Large / modular app Module per project with shared Contracts

project-structure