# Szymon P. Peplinski × Opus 4.7

- **Event:** [Built with Opus 4.7: a Claude Code hackathon](https://cerebralvalley.ai/e/built-with-4-7-hackathon)
- **When:** Apr 21 at 12:00 PM – Apr 27 at 2:00 AM (EDT)
- **Where:** Online
- **Team:** [Szymon Peplinski](https://cerebralvalley.ai/u/simm)
- **GitHub:** https://github.com/speplinski/hackathon-opus-47
- **Demo video:** https://youtu.be/i9PORz--Aws
- **Gallery:** https://cerebralvalley.ai/e/built-with-4-7-hackathon/hackathon/gallery
- **Page:** https://cerebralvalley.ai/e/built-with-4-7-hackathon/hackathon/gallery/60

Feedback enters the product process as evidence. It leaves as opinion. Auditable Design keeps the reasoning intact.

The system reads a public Duolingo review corpus, clusters recurring friction, audits it through six canonical design lenses (Norman, WCAG, Kahneman, Osterwalder, Cooper, Garrett), grounds findings in the actual product interface, proposes a direction, and re-audits before handoff.

The output is a single markdown brief: measured pain, priority reasoning, validated direction, and full provenance (SHA-256) for every input.

The brief is implementation-ready: the demo shows the brief and the corrected mockup side by side.

The key contribution of Opus 4.7 appears at the verification stage.

During real-product inspection, Opus 4.7 surfaced a pricing inconsistency no upstream layer identified: Super costs 500 gems on one screen and 450 on another — same product, same session.

This was not present in user feedback. It was not defined in the heuristic baseline. It required comparing pixels across separate screens.

Under identical conditions, Sonnet 4.6 confirmed all baseline heuristics but surfaced no additional findings. Opus 4.6 produced adjacent observations. Only Opus 4.7 produced a new, independent observation.

The difference is not accuracy. It is the ability to name what is missing.

Cost per cluster: around $1. A qualitative study: tens of thousands.

Not louder recommendations — better accountability.

Built with Claude Opus 4.7 and Claude Code.

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