Core Commands

Commands You’ll Use Daily

Claude Code has many commands. Most sessions use the same handful. Let’s nail those first.

File Context Commands

/add

Adds files to Claude’s context. This is probably the command you’ll use most.

Basic usage:

/add src/auth.js

Multiple files:

/add src/auth.js src/user.js src/session.js

Glob patterns:

/add src/components/**/*.tsx    # All TSX files in components
/add tests/*.test.js           # All test files
/add **/*.md                   # All markdown files

When to use:

• Before asking questions about specific code
• Before requesting changes to files
• When Claude needs to understand how files work together

Pro tip: Add files BEFORE asking questions. Claude gives better answers when it has seen the actual code.

/ls

Lists files in context.

/ls

Shows what Claude currently knows about. Use this to verify your /add commands worked or to see what’s accumulated in context.

Conversation Management

/clear

Wipes conversation history completely.

/clear

When to use:

• Starting a completely new task
• Context has become cluttered with irrelevant history
• Claude is confused or giving inconsistent responses
• You want a fresh start without restarting Claude Code

Warning: This is irreversible. Everything from the current session is gone.

/compact

Summarizes context to reduce size while keeping key information.

/compact

When to use:

• Context is getting large but you want to keep working
• Claude mentions approaching context limits
• Responses are slowing down

Difference from /clear: Compact preserves the essence of what you’ve discussed. Clear erases everything.

/undo

Reverts Claude’s last action.

/undo

When to use:

• Claude made a change you don’t want
• You want to try a different approach
• Something went wrong

Faster than manually reverting changes.

Help and Discovery

/help

Shows available commands.

/help

Commands change with updates. /help always shows what’s currently available.

/status

Shows current session state.

/status

Displays context usage, active files, and other session info.

Practical Patterns

Starting a New Task

/clear
/add src/feature-im-working-on/*
> Let's add caching to the data fetching layer

Clear slate. Relevant files. Specific task.

Midway Context Refresh

/compact
/add src/new-file-i-need.js
> Continue with the caching implementation. Now integrate with this new file.

Quick check: Before moving on, can you recall the key concept we just covered? Try to explain it in your own words before continuing.

Compact keeps history. Add new context. Continue where you left off.

Exploring an Unfamiliar Codebase

/add README.md package.json
> What does this project do and what's the tech stack?

/add src/index.js src/app.js
> Walk me through the main entry points

Start broad, then narrow in.

Reviewing Before Committing

/add $(git diff --name-only)
> Review these changes. Any bugs or issues?

Add only changed files. Focused review.

Common Mistakes

Adding too much:

/add src/**/*

Don’t add your entire codebase. Context has limits. Be selective.

Not adding enough:

> Why isn't this function working?

Claude can’t see the function. Add the file first.

Forgetting what’s in context:

# After many /add commands...
> Why are you referencing that old file?

Use /ls to see what’s actually in context. Use /clear if it’s cluttered.

Using /clear when /compact would work:

/clear
# Now I have to re-add everything and re-explain the task

If you want to keep session context but reduce size, use /compact instead.

Command Quick Reference

Exercise

Open Claude Code in a project and practice:

1. Add a few source files with /add
2. Use /ls to verify they’re in context
3. Ask a question about the code
4. Use /compact to see how it summarizes
5. Use /clear and notice the difference

Get comfortable with these before moving on. They’re the foundation for everything else.

Key Takeaways

• /add is your most important command—give Claude the right files
• /clear for fresh starts, /compact to reduce size while keeping context
• Check what’s in context with /ls when confused
• /undo is faster than manual reverting
• Less is more: selective context beats dumping everything

Next: how to manage context strategically for better results.

Up next: In the next lesson, we’ll dive into Context Management.