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Run npx skillmds@latest add fusengine/solid-csharp in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

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Is Solid Csharp free to use?

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Who published Solid Csharp?

fusengine (@fusengine) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Solid Csharp by fusengine — Agent Skill

Name: Solid Csharp
Rating: 4.666666666666667 (3 reviews)
Author: fusengine

File contents

Before writing any new code it requires a DRY check -- grep the codebase and Core/Services/Core/Contracts for existing logic to reuse before creating something new. See principles.md for the 5 SOLID principles and patterns.md for directory layout, testing, and record usage.

SOLID C# - Modular Architecture

Agent Workflow (MANDATORY)

Before ANY implementation, spawn 3 agents in parallel, one Agent call each with a name:

fuse-ai-pilot:explore-codebase - Analyze existing architecture
fuse-ai-pilot:research-expert - Verify .NET docs via Context7
fuse-ai-pilot:sniper - Post-implementation validation

DRY - Reuse Before Creating (MANDATORY)

Before writing ANY new code:

Grep the codebase for similar interfaces, services, or logic
Check shared locations: Core/Services/, Core/Contracts/
If similar code exists -> extend/reuse instead of duplicate
If code will be used by 2+ features -> create it in Core/

Architecture (Modules MANDATORY)

Layer	Location	Max Lines
Controllers	`Modules/[Feature]/Controllers/`	50
Services	`Modules/[Feature]/Services/`	100
Repositories	`Modules/[Feature]/Repositories/`	100
Contracts	`Modules/[Feature]/Contracts/`	30
Models	`Modules/[Feature]/Models/`	50
Shared	`Core/{Services,Contracts,Models}/`	-

NEVER use flat structure - always Modules/[Feature]/

Critical Rules (MANDATORY)

Rule	Value
File limit	100 lines (split at 90)
Controllers	< 50 lines, delegate to services
Interfaces	`Contracts/` directory ONLY
XML docs	Every public member documented
DI	Use `Microsoft.Extensions.DependencyInjection`
Small interfaces	1-3 members max
Records	Prefer `record` for DTOs and value objects

Reference Guide

Topic	Reference	When to consult
SOLID Principles	principles.md	Quick reference for all 5 principles
Patterns & Structure	patterns.md	Directory layout, testing, records

Forbidden

Anti-Pattern	Fix
Files > 100 lines	Split at 90
Interfaces in impl files	Move to `Contracts/` directory
Fat interfaces (4+ members)	Split into focused interfaces
Flat project structure	Use `Modules/[Feature]/`
`new` for dependencies	Use constructor injection + DI
Service Locator pattern	Use constructor injection

---name: solid-csharpdescription: Use when writing or refactoring C#/.NET code, structuring Modules/[Feature]/ layers, or defining Contracts/ interfaces (SOLID, files < 100 lines).---<objective>SOLID C# enforces a modular architecture for C# 12/.NET 9 projects: every feature lives under `Modules/[Feature]/` (Controllers, Services, Repositories, Contracts, Models) with shared code centralized in `Core/`, contracts are mandatory and live only in `Contracts/` directories, and interfaces stay small (1-3 members). File limits are strict (100 lines, split at 90; controllers under 50).Before writing any new code it requires a DRY check -- grep the codebase and `Core/Services`/`Core/Contracts` for existing logic to reuse before creating something new. See `principles.md` for the 5 SOLID principles and `patterns.md` for directory layout, testing, and record usage.</objective># SOLID C# - Modular Architecture## Agent Workflow (MANDATORY)Before ANY implementation, spawn 3 agents in parallel, one `Agent` call each with a `name`:1. **fuse-ai-pilot:explore-codebase** - Analyze existing architecture2. **fuse-ai-pilot:research-expert** - Verify .NET docs via Context73. **fuse-ai-pilot:sniper** - Post-implementation validation---## DRY - Reuse Before Creating (MANDATORY)**Before writing ANY new code:**1. **Grep the codebase** for similar interfaces, services, or logic2. Check shared locations: `Core/Services/`, `Core/Contracts/`3. If similar code exists -> extend/reuse instead of duplicate4. If code will be used by 2+ features -> create it in `Core/`---## Architecture (Modules MANDATORY)| Layer | Location | Max Lines ||-------|----------|-----------|| Controllers | `Modules/[Feature]/Controllers/` | 50 || Services | `Modules/[Feature]/Services/` | 100 || Repositories | `Modules/[Feature]/Repositories/` | 100 || Contracts | `Modules/[Feature]/Contracts/` | 30 || Models | `Modules/[Feature]/Models/` | 50 || Shared | `Core/{Services,Contracts,Models}/` | - |**NEVER use flat structure - always `Modules/[Feature]/`**---## Critical Rules (MANDATORY)| Rule | Value ||------|-------|| File limit | 100 lines (split at 90) || Controllers | < 50 lines, delegate to services || Interfaces | `Contracts/` directory ONLY || XML docs | Every public member documented || DI | Use `Microsoft.Extensions.DependencyInjection` || Small interfaces | 1-3 members max || Records | Prefer `record` for DTOs and value objects |---## Reference Guide| Topic | Reference | When to consult ||-------|-----------|-----------------|| **SOLID Principles** | [principles.md](references/principles.md) | Quick reference for all 5 principles || **Patterns & Structure** | [patterns.md](references/patterns.md) | Directory layout, testing, records |---## Forbidden| Anti-Pattern | Fix ||--------------|-----|| Files > 100 lines | Split at 90 || Interfaces in impl files | Move to `Contracts/` directory || Fat interfaces (4+ members) | Split into focused interfaces || Flat project structure | Use `Modules/[Feature]/` || `new` for dependencies | Use constructor injection + DI || Service Locator pattern | Use constructor injection |

Frequently asked questions

Solid Csharp