Lab 3.5: AI Peer Review

Module: 3.5 - Multi-Claude Workflows | ← SlidesDuration: 30 minutes Sample Project: hackathon-starter

Learning Objectives

By the end of this lab, you will be able to:

• Run multiple Claude Code sessions simultaneously
• Use one Claude to write code, another to review
• Work on parallel tasks in different terminals
• Leverage multiple perspectives for better code quality

Prerequisites

• Completed previous Day 3 labs
• Ability to open multiple terminal windows
• Familiarity with the hackathon-starter project

Why Multiple Claude Sessions?

Single Claude limitations:

• One context, one perspective
• Can't review its own work objectively
• Sequential task execution

Multi-Claude benefits:

• Fresh perspective for code review
• Parallel task execution
• Specialized roles (writer vs. reviewer)
• Cross-checking for errors

Setup

# Navigate to the sample project
cd sample-projects/hackathon-starter

# You'll need TWO terminal windows for this lab

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Task 1: Writer-Reviewer Pattern

Time: 15 minutes

Use one Claude to write code, another to review it.

Terminal 1 - The Writer:

claude

Give the Writer a task:

Create a new utility function in a file called utils/stringHelpers.js that:
1. Truncates a string to a max length with ellipsis
2. Converts a string to title case
3. Generates a URL-safe slug from a string

Include JSDoc comments for each function.

Wait for the Writer to complete.

Terminal 2 - The Reviewer:

claude

Give the Reviewer a task:

Act as a senior developer performing a code review.

Review the file utils/stringHelpers.js and check for:
1. Edge cases that aren't handled
2. Performance issues
3. Naming clarity
4. Missing error handling
5. Test coverage suggestions

Be constructive but thorough. Rate the code 1-10 and explain.

Compare perspectives:

• Did the Reviewer catch issues the Writer missed?
• Were the suggestions actionable?

Success criteria:

• [ ] Writer created the utility file
• [ ] Reviewer provided meaningful feedback
• [ ] At least one improvement identified

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Task 2: Implement Review Feedback

Time: 10 minutes

Have the Writer fix issues found by the Reviewer.

Terminal 1 - Back to the Writer:

The code review found these issues:
[Paste the Reviewer's feedback here]

Please address each issue and update the file.

Terminal 2 - Re-review:

Re-review utils/stringHelpers.js after the fixes.
Did the developer address all the feedback?
What's the new rating?

Success criteria:

• [ ] Writer addressed feedback
• [ ] Reviewer confirmed improvements
• [ ] Code quality improved measurably

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Task 3: Parallel Task Execution

Time: 5 minutes

Work on two independent tasks simultaneously.

Terminal 1:

Add input validation to the user registration endpoint in controllers/user.js.
Validate email format and password strength.

Terminal 2:

Write unit tests for the existing user profile update functionality.
Focus on edge cases.

Both tasks run in parallel, saving time.

Success criteria:

• [ ] Both tasks completed
• [ ] No conflicts between changes
• [ ] Time saved vs. sequential execution

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Workflow Patterns

Pattern 1: Writer-Reviewer

Claude A (Writer) → Creates code
Claude B (Reviewer) → Reviews code
Claude A (Writer) → Fixes issues

Pattern 2: Parallel Workers

Claude A → Task 1 (e.g., frontend)
Claude B → Task 2 (e.g., backend)

Pattern 3: Devil's Advocate

Claude A → Proposes solution
Claude B → Challenges assumptions, finds flaws
Claude A → Defends or improves

Pattern 4: Specialist Teams

Claude A → Security-focused review
Claude B → Performance-focused review
Claude C → Readability-focused review

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Tips for Success

1. Name your sessions - Use /rename to track which Claude is which
2. Clear context - Each Claude starts fresh, won't know what the other did
3. Copy outputs - Manually share relevant info between sessions
4. Use git worktrees - For larger parallel tasks, use separate worktrees

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Git Worktrees for Parallel Work

For larger parallel efforts:

# Create a worktree for the second Claude
git worktree add ../hackathon-feature-b feature-branch-b

# Terminal 1 works in main directory
# Terminal 2 works in ../hackathon-feature-b

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Troubleshooting

Sessions conflicting:

• Work on different files
• Or use git worktrees for isolation

Context confusion:

• Each session is independent
• Explicitly share relevant context via copy-paste

Too many sessions:

• Start with 2, add more only if needed
• More isn't always better

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When to Use Multi-Claude

Scenario	Recommendation
Quick code review	Yes - fresh perspective helps
Large refactoring	Maybe - coordinate carefully
Parallel independent features	Yes - saves time
Debugging a single issue	No - one focused session better
Security audit	Yes - multiple reviewers catch more

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Stretch Goals

If you finish early:

1. Try the Devil's Advocate pattern on an architecture decision
2. Set up git worktrees and work on two feature branches
3. Create a "review checklist" command for the Reviewer Claude

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Deliverables

At the end of this lab, you should have:

1. Experience running parallel Claude sessions
2. Code reviewed and improved by a second Claude
3. Understanding of when multi-Claude helps
4. Workflow patterns for your team

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Next Steps

After completing this lab, move on to Lab 3.6: CI/CD & Headless Mode.