EShop — Git skill for Claude Code

Speaking Copilot's Language

**Understand an unfamiliar codebase, verify what you learn, and give GitHub Copilot reusable context for the next investigation.**

This is Tim Warner's teaching fork of [dotnet/eShop](https://github.com/dotnet/eShop), a .NET application with multiple services. It gives us a real system to investigate: commands, domain events, database operations, and messages crossing service boundaries. You do not need to understand all of eShop before you begin.

The lesson follows one loop: **explore → verify → preserve → reuse**. Copilot helps you find and explain code. You check its explanation against the source, then record the useful knowledge in instructions, prompts, and skills that travel with the repository.

**Start here:** [Use the repository map](docs/repo-map.md) · [Try the investigation](#try-the-investigation) · [Five prompts to try](docs/try-these-prompts.md) · [Read the HTML leave-behind](docs/copilot-context-engineering.html) · [See the context files](#the-context-layer) · [Run eShop](docs/eshop-application.md)

What you will learn

By the end, you should be able to:

• Trace one business flow through an unfamiliar application using file and method references.
• Distinguish evidence from inference, including existing warnings, assumptions, and unanswered questions.
• Choose where knowledge belongs: repository instructions, path-scoped instructions, a reusable prompt, or an agent skill.
• Preserve both a verified fact and a reasoning rule so the next investigation benefits from what you learned.
• Improve the next investigation without making every request carry an entire architecture manual.

The examples use C#, but the method applies to any language. Familiarity with functions, services, and database writes is enough to follow the investigation.

Why context matters

Copilot builds an answer from the context available to it. In VS Code, an agent can search by meaning, search for exact text, follow symbo