Solving Complex Problems

Working Code

Let's tackle a complex task with Plan mode. Press Shift+Tab to switch to Plan mode:

[Plan mode]
> Create a plan to migrate this Express app to NestJS.

Claude only presents a plan without changing any code:

Migration Plan:

Step 1: Set up NestJS project structure
  - Add @nestjs/core, @nestjs/common, etc.
  - Create module/controller/service directory structure

Step 2: Convert routes to controllers
  - GET /api/users → UsersController.findAll()
  - POST /api/users → UsersController.create()
  ...

Step 3: Convert middleware to Guards/Interceptors
  ...

If the plan looks good, switch back to normal mode (Shift+Tab):

> Execute step 1 of the plan above

Try It Yourself

Try Think mode. Include "think" in your prompt to make Claude reason more deeply:

> Analyze the performance bottleneck in this code. Think about it carefully (think).
> @src/api/search.ts

For stronger reasoning:

> Analyze the problems in this architecture and suggest improvements.
> Think about it very carefully (think hard).
> @src/

Compare the depth between a normal response and a Think mode response.

"Why?" — Think Before You Act

Jumping straight into execution on complex tasks can send things in the wrong direction. Plan mode is a safe space for planning without touching code.

Plan Mode vs Normal Mode

| Aspect | Plan Mode | Normal Mode | | ----------------- | ----------- | ----------------- | | File editing | Not allowed | Allowed | | Command execution | Not allowed | Allowed | | Analysis/planning | Optimized | Execution-focused | | How to switch | Shift+Tab | Shift+Tab |

Think Mode Intensity

| Prompt | Intensity | Use Case | | -------------- | --------- | ------------------------------------- | | "think" | Basic | General analysis | | "think hard" | Enhanced | Complex architecture decisions | | "think harder" | Maximum | Subtle bugs, performance optimization |

When to Use Plan Mode

• Architecture changes (framework migration, structural redesign)
• Uncertain direction (multiple possible approaches)
• Impact analysis before large-scale refactoring
• Tech stack selection (comparing pros and cons)

Deep Dive