Testing vs Design · both proven

systematic-debugging vs vercel-composition-patterns

Both skills were run through Claude twice: once on a fixed brief without the skill, once with it. The briefs differ because each is written for the job the skill claims to do, so compare each skill against its own baseline, then decide which difference matters for your work. They are in different categories, so this is a choice of job, not a head-to-head on the same job.

systematic-debugging

Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes

Category: Testing
Source: obra/superpowers
License: MIT
Proof model: claude-opus-5-5
Brief: “A Node.js API returns 500 for about 1 in 200 requests to POST /orders. Logs show 'TypeError: Cannot read properties of undefined (reading "id")' at orders.js:48, which reads req.user.id. The route is behind an auth middleware. The failures started after a deploy that added a 30-second cache on the session lookup. Present your diagnosis and fix as a single HTML page: what you checked, in order, the root cause, the code change, and how you would confirm it is fixed.”
Skill commit: bb92a77

Without the skillWith systematic-debugging

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Without, runWith systematic-debugging, run3 independent runs per side, none selected by hand.

Download the with-skill page

vercel-composition-patterns

React composition patterns that scale. Use when refactoring components with boolean prop proliferation, building flexible component libraries, or designing reusable APIs. Triggers on tasks involving compound components, render props, context providers, or component architecture. Includes React 19 API changes.

Category: Design
Source: vercel-labs/agent-skills
License: Not stated
Proof model: claude-opus-5-5
Brief: “Refactor this React Modal component. It currently takes fourteen props, including isConfirm, isDanger, showFooter, footerAlign, hideClose, title, subtitle, icon, primaryLabel, secondaryLabel, onPrimary, onSecondary, size and children, and a dozen screens pass different combinations of them. Present the refactor as a single HTML page with the new API, the implementation, three call sites rewritten before and after, and a short note on why the new shape scales.”
Skill commit: 063bee9

Without the skillWith vercel-composition-patterns

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Without, runWith vercel-composition-patterns, run3 independent runs per side, none selected by hand.

Download the with-skill page

We don’t pick a winner for you: the pages are the evidence. Both proofs can be repeated with the brief, model and commit shown above. See alternatives to systematic-debugging or alternatives to vercel-composition-patterns.