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plan then act
The model writes the steps. You approve. Then it may touch files. Not the other way around.
What is plan then act?
Plan-then-act is a two-phase agent loop: a plan with no side effects, a human gate, then execution. ReAct mixes thought and tools in one stream; plan-then-act splits them on purpose.
Why does plan then act matter when vibe coding?
Agents that “just start” will refactor while exploring. The plan is cheap. The diff is not. Make the plan the first artifact you accept.
How do you do plan then act?
Every non-trivial turn starts with “plan only.” Reject plans that touch more than the slice. Then a second turn: execute this plan, nothing else.
How do you ask a model for plan then act?
Plan only. No file edits, no commands that write. Numbered steps, files you would touch, tests you would run. Wait for OK.
What goes wrong with plan then act?
Approving a plan that says “and clean up nearby.” Nearby is how a slice becomes a rewrite.