Plan mode
Plan mode makes an AI coding tool propose an approach before it edits anything. You see the intended sequence of changes, approve or correct it, and only then does the agent execute. It exists to catch bad architecture at the point where fixing it costs one message.
The economics are the whole argument. Correcting a plan costs a sentence. Correcting the result of that plan costs reviewing and reverting a pile of diffs, and often a second attempt that inherits assumptions from the first.
It is most valuable exactly where agents are most useful and most risky: multi-file work where you cannot see the shape of the change until it is done.
What this means in practice
Where a tool has no explicit plan mode you can ask for the behaviour: end the prompt with "propose a plan and wait for my approval before editing." That single clause is one of the highest-value habits in agentic coding, and it works in every tool we cover.
The plan-first clause, portable to any tool
[your task description] Before editing anything: propose a plan — the files you will touch, in what order, and what could break. Wait for my approval. When I reply, I will either say "go" or correct the plan. A corrected plan replaces the old one; do not merge old and new steps.
Works verbatim in tools with no explicit plan mode; the last line prevents the half-old-half-new plan that causes most post-approval surprises.
Prompts for the tools this applies to
Related terms
- Agent mode
Agent mode is the setting in an AI coding tool where the model can act rather than only answer: creating and editing files, running terminal commands, and iterating on the result.
- Ask mode
Ask mode is the read-only setting in an AI coding tool: the model answers questions about your code and explains what it finds, but does not edit files or run commands.
- Spec-driven development
Spec-driven development means writing a precise specification before generating any code, then using that spec as the prompt.
- PRD for AI
A PRD for AI is a product requirements document written to be consumed by an AI coding tool rather than by a team.