Two minutes in plan mode.
An hour you don’t unpick.

What’s inside

• The 5-second test — the one question that decides whether you plan or just prompt, before you type anything.
• The four planning surfaces — plan mode, the writing-plans skill, CLAUDE.md and a one-line decision log. When to use which.
• The plan-first workflow — goal → context → constraints → plan → accept → execute. The 90-second sequence.
• Anatomy of a good plan — acceptance criteria, file map, dependencies, rollback, open questions. Everything else is fluff.
• Plan vs prompt vs skill — the 2× rule for deciding when something becomes a skill (and how plan mode helps you write it cleanly).
• The empty-plan trap — and a worked example of planning a medium project the right way, step by step.