The WIN reel calls this selection-and-refinement pattern the Darwin Loop: make three candidates, choose the strongest, and evolve that winner into three improved versions. This guide turns the idea into a small, inspectable exercise. The name is a label for the workflow in the reel, not an official Anthropic feature or a special command you need to install.
Start with one ordinary draft. Branch only when you can explain what needs to improve. A clear comparison and a stopping point matter more than the number of agents you run.
Start with a draft and a finish line
Use a Claude conversation for writing, planning or design alternatives. Use an existing Claude Code project when the result needs files, code execution or tests. The basic exercise does not require three simultaneous agents. Claude can propose three alternatives in one conversation; separate agents are an optional implementation with their own setup and usage costs.
If you are new to Claude Code, follow its current setup guide before adapting the coding example. Work in a project you can restore, and give Claude the checks that already belong to that project.
Create one modest baseline first. For example: a weekend-trip planner with a destination field, a three-day itinerary and a save action. This travel-app exercise is an illustrative example. It is not a claim that a production application was built and tested in a single prompt.
Copy the three-line loop
Replace the brackets with your actual task, existing draft and criteria. Keep the first round small enough that you can inspect all three candidates.
1. Starting from this draft: [paste or reference it], create three meaningfully different approaches to [task]. Preserve [constraints]. Keep each candidate to [size or scope]. 2. Compare the three candidates against [three concrete criteria]. Show evidence, tradeoffs and unresolved problems. Recommend a winner, then stop and let me choose. 3. After I choose, evolve the winner: preserve its strongest parts and create three improved variations, each addressing a different specific weakness. Show exactly what changed. Run only one evolution round, then stop for my review.
The third line is the useful constraint: the next generation inherits a selected baseline. It should not restart with three unrelated answers. This is an original prompt template, not an Anthropic-provided command or a benchmarked recipe.
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Unlocks: Choose with evidence, not a flattering score · A small app example you can adapt · Keep the token budget bounded · What Anthropic’s loop guidance supports
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