Claude Code Course 2026

A four-session hands-on course on building with Claude. Each week you’ll extend devlens — a small AI coding assistant that reads your project files and answers questions about your codebase.

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What you’ll need

Accounts

• GitHub account — to fork this repo and submit your work
• Anthropic API key — your instructor will provide one. Get it from console.anthropic.com if you need your own.

Software to install

Node.js (v18 or later)

• Download from nodejs.org — install the LTS version

Claude Code (the CLI)

npm install -g @anthropic-ai/claude-code

VS Code (recommended editor)

• Download from code.visualstudio.com
• Install the Claude Code extension from the VS Code marketplace

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Getting started

1. Fork this repo Click “Fork” in the top right on GitHub. This gives you your own copy to push changes to.

2. Clone your fork

git clone https://github.com/YOUR_USERNAME/claude-code-course-2026.git
cd claude-code-course-2026

3. Install dependencies

npm install

4. Add your API key

cp .env.example .env

Open .env and replace your-api-key-here with the key your instructor gave you.

Never commit your .env file. The repo already includes a .gitignore that blocks it, but double-check before pushing: run git status and make sure .env does not appear in the list.

5. Run devlens

node index.js

Open http://localhost:3000 in your browser.

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Using Claude Code with your API key

Claude Code can run using your course API key instead of a Claude.ai subscription:

export ANTHROPIC_API_KEY=your-api-key-here
claude

To make this persist across terminal sessions, add the export line to your ~/.zshrc or ~/.bashrc, then restart your terminal.

Note: Your API key has a usage budget. It covers in-class work on this project — avoid using it for unrelated projects.

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Week 1 assignment

This week is about understanding how Claude actually works under the hood — specifically the messages array that drives every AI conversation.

What to submit

Push two commits to your fork:

Commit 1 — commented api.js (without CLAUDE.md)

• Open api.js in your editor
• Use Claude Code to ask questions: “What does this file do?”, “Walk me through the agent loop”, “What is the messages array?”
• Add comments to api.js in your own words explaining what you learned
• Commit: git commit -m "feat: add api.js comments"

Commit 2 — CLAUDE.md + rewritten comments

• Write CLAUDE.md by hand — your background, how you learn best, how you like Claude to talk to you
• Ask Claude the same questions again — notice how the answers change
• Rewrite your comments based on the better explanations
• Commit: git commit -m "feat: add CLAUDE.md and rewrite comments"