design-it-twice

Design It Twice

When invoked with $ARGUMENTS, treat the argument as the design problem to explore. Do not assume a solution. Start from the problem statement and generate at least two fundamentally different approaches independently. If a design already exists in the conversation or codebase, dispatch the clean-room-alternative agent (see Isolation Mode below) rather than trying to produce a second attempt yourself — a design already sitting in your context contaminates anything you write next, no matter how deliberately you try to ignore it. Then compare all approaches on concrete criteria.

This skill has two modes. Before a design exists, use it to generate and compare alternatives directly. After a design exists, dispatch the isolated agent described below to produce an independent second attempt that isn't anchored to the first. Either way, the first idea is unlikely to produce the best design, not because the designer isn't smart, but because the problems are genuinely hard.

When to Apply

• Before committing to a class, module, or API design
• When choosing between architectural approaches
• When an interface feels awkward but "good enough"
• When writing a design document or RFC
• When you catch yourself thinking "this is obviously the right way"

When NOT to Apply

• Trivial decisions with negligible consequences
• Well-established patterns where the design space is explored
• Bug fixes that don't change the interface
• Cost of the exercise should be proportional to cost of getting the design wrong

The Procedure

1. Generate at least two fundamentally different approaches, not variations on one idea. If both share an interface shape, they're variations. Push until the second makes you uncomfortable.

2. Compare the designs on concrete criteria:

   • Caller ease-of-use: Which requires less work from higher-level code? (primary criterion)
   • Interface simplicity: Which is easier to learn and use?
   • Generality: Which handles more use cases without special-casing?
   • Implementation complexity: Which is easier to get right?
   • Performance characteristics: Are there meaningful performance differences?