# Plan a big change first (/how-to/plan-a-big-change)



## 1. Switch to Plan mode [#1-switch-to-plan-mode]

Press `shift+tab` until the line under the prompt shows `Plan`, or type:

```text
/mode plan
```

In Plan mode the agent reads and thinks, and changes nothing until you approve its plan. See
[Choose a permission mode](/permission-modes).

## 2. Describe the change [#2-describe-the-change]

Say what you want and what matters to you:

```text
move login from session cookies to OIDC with our Keycloak; keep the current sessions working until everyone has logged in again
```

The agent reads the code. When a choice is yours, such as which library to use, it asks, and you pick an answer in the
question panel.

## 3. Review the plan [#3-review-the-plan]

When the plan is ready, it shows in the conversation and the plan panel asks `Ready to start? The plan is above.`

To change it, pick **No, keep planning**, press `n` and say what should change. The agent writes the plan again.

## 4. Start the work [#4-start-the-work]

Pick how freely the agent goes on:

| Choice                     | Then                                                                                                                                                      |
| -------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Yes, and use auto mode     | A safety classifier lets routine actions run and stops risky ones; writes outside the project still ask, and commits too unless `/commit-approval` is off |
| Yes, and accept edits      | Edits files in the project without asking; asks before risky commands                                                                                     |
| Yes, and approve each edit | Asks before every edit and every command outside a safe list                                                                                              |

The mode you pick stays on after the plan, in this project. The agent works through the plan step by step, with its task list above the
prompt.

## 5. Review the result [#5-review-the-result]

Type `/diff` and use `left` and `right` to go through the change one turn at a time. See
[Review changes](/review-changes).

<Callout>
  For a change that takes a while, turn on [worktrees](/worktrees) first. The work happens on a branch of its own, and
  your checkout stays free for other work.
</Callout>