claude-code-agent-loop/exercises/02-control-the-loop.md

Exercise 02: Control the Loop

Concept: The Agent Loop (CC-001) Level: Intermediate Time: ~15 minutes

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Objective

Learn to steer the agent loop instead of just watching it. You will use Plan Mode to preview what Claude intends to do before it acts, and use /rewind to undo a wrong turn.

Exercise 01 showed the loop running freely. This exercise shows you the controls.

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Before You Start

Confirm you have:

• Completed Exercise 01 (or understand the basic loop concept)
• Claude Code open in this directory

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Part A: Plan Mode

Step 1: Press Shift+Tab until the mode indicator shows plan.

You should see the permission mode change in the bottom bar. In Plan Mode, Claude will describe what it plans to do instead of doing it.

Step 2: Paste this prompt:

Create a project structure for a simple blog:
- A folder called blog/ with index.html, style.css, and posts/
- An about.html page
- A README.md explaining the structure

Step 3: Read Claude's plan.

Claude will describe the files it would create, the structure, and the content. It will NOT create anything yet. This is the plan.

Step 4: If the plan looks good, type:

Go ahead, execute this plan.

Or press Shift+Tab back to a normal mode and re-send the prompt.

Claude now executes, creating the actual files.

Why this matters: For complex tasks where a wrong start wastes time, Plan Mode lets you course-correct before any files are written.

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Part B: Using /rewind

Step 1: Give Claude an intentionally vague prompt:

Improve the blog project.

Claude will likely make some changes you did not expect or want. That is the point of this exercise.

Step 2: After Claude finishes, review what it changed. If the changes are not what you wanted, type:

/rewind

This restores your context to the state before Claude's last action. The files are unchanged (Claude did write them), but the conversation context is rewound so you can try a different approach.

Step 3: Now give a more specific prompt:

Add a navigation bar to index.html that links to about.html.
Do not change anything else.

Notice how specificity gives the loop better direction.

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Part C: Stopping a Runaway Loop

Step 1: Give Claude a deliberately open-ended task:

Make this blog production-ready.

Step 2: As Claude starts working (adding frameworks, build tools, etc.), press Escape to interrupt.

Claude stops mid-execution. You can then redirect:

Stop. I just want the HTML and CSS to be clean and valid.
No frameworks, no build tools.

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Expected Output

After completing all three parts:

• A blog/ directory with index.html, style.css, posts/, about.html, README.md
• You experienced Plan Mode (preview before execution)
• You used /rewind to undo a vague prompt
• You interrupted a runaway loop with Escape

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What You Learned

• Plan Mode previews: Shift+Tab toggles Plan Mode, where Claude describes its plan before acting
• /rewind undoes context: It rolls back the conversation so you can try a different approach
• Escape interrupts: Press Escape to stop Claude mid-loop when it is going in the wrong direction
• Specificity guides the loop: Vague prompts produce unpredictable results. Specific prompts keep the loop on track.

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Clean Up

rm -rf blog/ about.html

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Next

Ready to design prompts that work with the loop? Move to Exercise 03: Design for the Loop.