Plan Mode and Extended Thinking

Plan Mode activates Claude's Extended Thinking capability, allowing it to reason through complex problems before taking action.

What is Extended Thinking?

Extended Thinking gives Claude more "thinking time" to:

• Analyze complex requirements
• Consider multiple approaches
• Plan multi-step implementations
• Identify potential issues upfront

Activating Extended Thinking

Use these magic words in your prompts:

Example:

> think hard about how to refactor our authentication
> system to support OAuth2 and SAML

The Planning Process

When you activate Plan Mode, Claude will:

1. Analyze the current state
2. Identify requirements and constraints
3. Design an implementation strategy
4. Create a step-by-step plan
5. Present the plan for your approval
6. Execute upon confirmation

When to Use Plan Mode

Complex Refactors

> ultrathink about migrating from REST to GraphQL

Architecture Decisions

> think hard about the best way to implement
> real-time notifications in our app

Debugging Complex Issues

> think about why our memory usage keeps increasing
> after processing large files

Multi-service Changes

> ultrathink about adding a new payment provider
> that needs changes to frontend, backend, and database

Best Practices

Provide Context

Extended Thinking works best with context:

> We have a Next.js app with Prisma ORM and Redis cache.
> think hard about implementing a new caching strategy
> for user profiles that invalidates properly.

Review the Plan

Always review the plan before execution:

Claude: Here's my plan:
1. Create new cache invalidation service
2. Update user profile queries
3. Add Redis pub/sub for real-time invalidation
4. Update tests

> Approve? (y/n/e)

Iterate on Plans

You can refine the plan:

> Good plan, but also consider backwards compatibility
> with the mobile app v1.x

Next Steps

In the next module, you'll learn about CLAUDE.md and memory systems for persistent context.