Plan Mode
Research First, Implement Second
Video Lesson Coming Soon
A video walkthrough for this module is in production. For now, dive into the written content below.
What You'll Learn
- ✓ The problem Plan Mode solves
- ✓ Activating Plan Mode
- ✓ The research-then-implement workflow
- ✓ A real Plan Mode example
- ✓ When to use Plan Mode vs direct execution
- ✓ Extended thinking and deeper reasoning
In this module 6 sections
The Problem Plan Mode Solves
Without Plan Mode, you say "fix the authentication bug" and Claude Code starts editing files immediately. Sometimes this works perfectly — for simple, well-understood tasks, direct execution is the fastest path.
But for complex tasks — a bug in unfamiliar code, a refactor touching ten files, a feature that needs architecture decisions — you want Claude Code to investigate first. Read the code. Understand the problem. Propose a solution. Wait for your approval.
That is exactly what Plan Mode does. It puts Claude Code into read-only mode. It can read any file, search the codebase, trace code paths, and reason about the problem. But it cannot edit files, run commands, or change anything. It thinks first, then acts.
Activating Plan Mode
# Method 1: Keyboard shortcut
# Press Shift+Tab twice to toggle Plan Mode on/off
# Method 2: Slash command
/plan
# Method 3: Start a session in Plan Mode
claude --permission-mode plan
# You will see an indicator in your prompt showing
# that Plan Mode is active. The prompt changes to:
# [Plan Mode] >The Research-Then-Implement Workflow
Press Shift+Tab twice or type /plan. The prompt indicator changes to show you are in Plan Mode.
Tell Claude Code what you want to accomplish. Be specific about the goal but let it figure out the approach.
Claude Code reads relevant files, traces code paths, checks dependencies, and builds understanding of the problem. It might read 10, 20, or 50 files to fully understand the situation.
Claude Code presents its findings and proposes a plan: what it found, what it thinks the problem is, and what changes it recommends. You review and adjust.
When you are happy with the plan, press Shift+Tab twice to exit Plan Mode. Claude Code now has full context and implements the plan efficiently.
A Real Plan Mode Example
[Plan Mode] > The login form sometimes shows a blank
screen after submitting. Find the bug.
--- Claude Code's analysis ---
I've investigated the login flow. Here's what I found:
Files examined:
- src/pages/login.tsx (the login form component)
- src/lib/auth.ts (authentication logic)
- src/hooks/useSession.ts (session management)
Root cause:
In auth.ts line 47, the redirectAfterLogin() function
is called before the session token is saved to storage.
This creates a race condition where the redirect happens
but the session check on the destination page fails,
showing a blank screen.
Proposed fix:
1. Move the redirect call after the token save (auth.ts)
2. Add a loading state while session initializes (login.tsx)
3. Add a test for the login redirect flow (auth.test.ts)
Shall I implement this?When to Use Plan Mode
| Scenario | Use Plan Mode? | Why |
|---|---|---|
| Bug in unfamiliar code | Yes | Needs investigation before fixing |
| Add a simple test | No | Straightforward — direct execution is faster |
| Refactor across 10+ files | Yes | Needs coordination and a clear plan |
| Fix a typo | No | Trivial — no planning needed |
| Add a new feature | Yes | Needs architecture decisions |
| Update a dependency | Maybe | Depends on whether there are breaking changes |
| Explore unfamiliar code | Yes | Read-only exploration is exactly what Plan Mode does |
Extended Thinking
For the hardest problems, Claude Code uses extended thinking — a deeper reasoning mode that works through complex logic step by step. In Plan Mode, this happens naturally. Claude Code takes longer to respond, but its analysis is more thorough and its plans are more reliable.
You do not need to activate extended thinking manually. Claude Code uses it automatically when the problem requires it.
Key Takeaways
Plan Mode (Shift+Tab twice) puts Claude Code in read-only mode — it investigates but does not change anything
The research-then-implement workflow prevents the most common mistake: changing code before understanding the problem
Use Plan Mode for complex bugs, multi-file refactors, new features, and unfamiliar code exploration
Extended thinking gives Claude Code deeper reasoning for the hardest architectural problems