Plan mode: think before editing

What you’ll be able to do

Use plan mode to get an approach you agree with before any code changes, then carry it out with confidence.

Explore → Plan → Code → Commit

For anything non-trivial, the most reliable workflow is:

1. Explore. Have Claude read the relevant code. No edits.
2. Plan. Have it propose an approach. Push back and refine.
3. Code. Carry out the plan, verifying as you go.
4. Commit. Review the diff and commit with a good message.

Plan mode enforces steps 1–2.

Entering plan mode

Press Shift+Tab to cycle permission modes until the status line shows ⏸ plan mode on. You can also start in it:

claude --permission-mode plan

In plan mode Claude reads files and runs read-only commands, but edits stay blocked. When it’s ready, it presents a plan and asks whether to proceed. When you approve, you choose which mode carries out the plan, for example auto mode for an unattended run, or accept edits.

Exercise: plan a real feature

In a project of your own (or the loop-practice repo):

1. Enter plan mode.

2. Ask for something meaningful that spans several files, for example:

   I want to add rate limiting to all API routes: 100 req/min per IP, with a
   429 JSON response. Investigate how routes are registered and propose a plan.

3. Critique the plan. Ask at least one probing question:

   • “Where does the limit state live? What happens with multiple server instances?”
   • “Which routes should be excluded, like health checks?”
   • “How will we test it?”

4. Once you’re happy, approve the plan and let Claude carry it out.

5. Review the result against the plan. Did it do what was agreed?

Make Claude think harder

For tricky problems, raise the reasoning effort:

• For one prompt: include the keyword ultrathink, e.g. “ultrathink: what could go wrong with this migration plan?”
• For the session: /effort opens a slider (low → medium → high → xhigh → max)
• Plan with a big model, build with a fast one: /model opusplan uses Opus in plan mode and Sonnet for execution

More effort costs more tokens, so save it for the decisions that deserve it.

Save plans for big work

For multi-session work, ask Claude to write the plan to a file:

Write this plan to docs/plans/rate-limiting.md as a checklist.

Later, in a fresh session: “Continue with @docs/plans/rate-limiting.md. Pick up the next unchecked item.” The plan survives /clear and works as shared memory. In Module 8 you’ll use /goal to have Claude work through a checklist like this until it’s done.

Verify it worked

• You entered plan mode with Shift+Tab
• You changed the plan with at least one question before approving it
• The finished change matched the agreed plan
• (Optional) You saved a plan to a file and resumed from it after /clear