Plan mode

What plan mode does

In plan mode, Claude reads and proposes. Edits stay blocked until you approve the plan. Enter it with Shift+Tab, with --permission-mode plan, or with /plan [description], which can take the task as its argument.

The mechanism is small but the effect is large: the first thing you review is the approach, not a diff. Changing a plan costs you a sentence. Changing a finished implementation costs you the work.

When the plan arrives, Ctrl+G opens it in your editor so you can edit it directly. When you accept it, the session gets a generated title, and the showClearContextOnPlanAccept setting adds a choice to clear the context before implementation starts.

Three phases

Think of the work as three phases: explore, plan, implement.

The first two phases are where plan mode lives. Exploring is cheap and safe, because nothing changes. The plan is the artifact you can argue with. Only then do you leave plan mode and let edits happen.

One cost detail from the docs fits here: the opusplan model alias uses Opus while planning and Sonnet while executing. The thinking-heavy phase gets the stronger model, and the mechanical phase gets the cheaper one.

When planning pays

Plan first when the approach is the risk. Good signals:

• The change touches several files or modules, and a wrong first choice spreads.
• You are not sure how the existing code works, and the plan will show you what Claude understood.
• There is more than one reasonable design and you want to choose.
• The work is long, so you want an agreed script before it runs unattended.

For that last case there is also the interview pattern from the guide: ask Claude to interview you until it could write a spec, write SPEC.md, then build in a fresh session. The new session starts with the spec and nothing else.

When planning is a waste

Skip it when the diff fits in one sentence. Fixing a typo, renaming a variable, or adding one log line does not need a proposal and an approval. You would spend more effort reviewing the plan than reviewing the change.

A plan is also not a guarantee. In an interactive terminal where bypass is available, the edit block of plan mode is not enforced: Claude is told not to edit, but edits would run. If you need a hard read-only session, do not rely on plan mode with bypass enabled.