How to Build Your Own AI for Vibe Coding in .NET

Introduction

You’ve probably used GitHub Copilot, ChatGPT, or Cursor for vibe coding—where you type your intent and AI writes the code. But what if you could build your own AI developer that vibes with your coding style, project conventions, and business logic?

In this article, we’ll walk through how to build a custom AI assistant tailored for vibe coding using:

• Azure OpenAI or OpenAI Assistants API
• Your own .NET tooling
• Prompts trained on your own codebase
• Agent memory and context for iterative development

Yes—you’re about to build an AI that codes the way YOU code.

What Is a Vibe Coding AI?

A Vibe Coding AI is a lightweight agent that:

• Understands your prompts like “build an API for orders”
• Knows your stack (e.g., ASP.NET Core, EF Core, Clean Architecture)
• Writes production-grade code instantly
• Refines it as you iterate or correct
• Optionally integrates into your IDE or CLI

You’re not just calling GPT—you’re creating a personal coding partner.

Tech Stack

• .NET 8 or 10
• OpenAI GPT-4-turbo (via Assistants API or Azure OpenAI)
• Custom tools or plugins (optional)
• A knowledge base (your code, doc, style guides)

Step 1: Define the Assistant

var assistant = new OpenAIAssistant("vibe-coder", "gpt-4");
assistant.SetInstructions("""
You are an expert .NET developer. 
Follow Clean Architecture principles. 
Use ASP.NET Core 10 and C#. Use camelCase naming. 
""");

Add some starter memory:

assistant.AddMemory("""
- Our domain layer uses 'IRepository'
- We use FluentValidation for model validation
- We log via Serilog
""");

Step 2: Define Prompt Flow

Send a simple vibe prompt:

var prompt = "Create a POST endpoint to create a new Customer and validate name + email";
var response = await assistant.GenerateCodeAsync(prompt);
Console.WriteLine(response);

Expected response:

[HttpPost]
public IActionResult Create(CustomerDto dto)
{
    var validator = new CustomerValidator();
    var result = validator.Validate(dto);

    if (!result.IsValid)
        return BadRequest(result.Errors);

    var customer = _mapper.Map<Customer>(dto);
    _repo.Add(customer);
    return Ok(customer);
}

Step 3: Extend with Custom Tools (Optional)

Define custom tools if you want the assistant to read your code, scaffold tests, or publish documentation:

assistant.RegisterTool(new ReadFileTool("Controllers/CustomerController.cs"));
assistant.RegisterTool(new GenerateUnitTestTool());
assistant.RegisterTool(new MarkdownDocTool());

Now you can prompt:

“Generate unit tests for the Customer controller using xUnit”

And it will do just that.

🔄 Step 4: Continuous Refinement
You can add multi-turn conversations:

await assistant.SendMessageAsync("Use record types for DTOs instead of classes.");
await assistant.SendMessageAsync("Add async to repository method.");
await assistant.SendMessageAsync("Now write integration test for the API.");

The assistant remembers your preferences and adjusts output accordingly.

Ideas for Integration

• Vibe Coding CLI
  dotnet vibe "Generate CRUD for Product"
• In-IDE plugin (Visual Studio Code / Rider)
  Right-click > “Generate with VibeAI”
• Code Review Bot
  Let the assistant suggest PR improvements based on team conventions

Benefits

• Speeds up repetitive scaffolding
• Follows your exact structure and patterns
• Offers explainable and tweakable code
• Gives your team a consistent starting point

Limitations

• Still needs human review
• Context limits (be selective in what memory you feed it)
• No understanding of complex runtime behavior (yet)

Bonus: Feed Your AI Your Codebase

Train your vibe assistant on:

• Domain layer
• Common patterns
• Naming conventions
• Typical validation rules
• Sample PRs with comments

This way, your AI starts writing exactly like your team from day one.

Conclusion

You don’t need to wait for the next AI product to drop — you can build your own vibe coding AI now.

With .NET, GPT-4, and your team’s coding knowledge, you can:

• Scaffold faster
• Code cleaner
• Write like yourself, but turbocharged

Start small. Add memory. Plug in tools. And soon, you’ll wonder how you ever coded without your vibe partner.