# lean-ux

Turns interface work into declared assumptions, testable hypotheses and the cheapest experiment that answers the question. Useful when specs grow faster than evidence.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 5500 installs · ★ 2508
- Author: wondelai
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/wondelai/skills/tree/HEAD/lean-ux/SKILL.md
- Updated: 2026-09-10
- HTML: https://affpapa.org/en/nevibecode/skills/lean-ux

## What it does

The skill switches the agent into Lean UX mode. It pulls the user and business assumptions out of a task, ranks them by risk and uncertainty, then rewrites the shakiest ones as hypotheses with a fixed shape: persona, action, measurable signal. From there it picks the lowest-fidelity experiment that can actually settle the argument, whether that is a paper prototype, a clickable mockup or a landing page collecting early-access signups.

It also carries an eight-row diagnostic of your process. The agent scores each row, roughly 1.25 points per yes, names the rows that failed and gives a fix for each one. Two reference files go deeper: `references/hypothesis-canvas.md` holds the risk/uncertainty matrix and fillable templates, and `references/outcome-metrics.md` covers outcome versus output metrics.

The ethics section is blunt. If leadership has already committed to a direction, the skill says to admit the constraint instead of staging a fake falsification. Proto-personas are allowed in place of full research, with the caveat that they must be validated later. That caveat is the reason to skip this skill on a team where design decisions arrive as orders.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add wondelai/skills --skill lean-ux -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/lean-ux/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/lean-ux/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add wondelai/skills --skill lean-ux -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/lean-ux/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add wondelai/skills --skill lean-ux -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/lean-ux/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install wondelai/skills lean-ux
```

2. **Manually: put the files in place**
- File: `.github/skills/lean-ux/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add wondelai/skills --skill lean-ux -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/wondelai/skills --path lean-ux
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/lean-ux/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add wondelai/skills --skill lean-ux -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/wondelai/skills/tree/HEAD/lean-ux/SKILL.md

## When to use it
- surface user assumptions before anyone opens a design tool
- write a hypothesis with a pre-committed success criterion
- match experiment fidelity to the risk of an assumption
- score a design process against the eight-row diagnostic
- get designers and engineers sketching in the same session

## Example prompts
- Run an assumption map on our checkout redesign using Lean UX.
- Write a hypothesis for the onboarding wizard and pick the lowest-fidelity experiment that could kill it.
- Score our design workflow with the Lean UX diagnostic and list the failing rows.

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 2100ed5e32553f78.

BEGIN THIRD-PARTY FILE 2100ed5e32553f78
```text
---
name: lean-ux
description: 'Apply lean thinking to UX: hypothesis-driven design, collaborative sketching, and rapid experiments instead of heavy deliverables. Use when the user mentions "Lean UX", "design hypothesis", "outcome over output", "design studio method", "assumption mapping", "lightweight research", "too much design documentation", or "get the team designing together". Also trigger when reducing design-documentation overhead, getting cross-functional teams to co-design, or running fast usability experiments. Covers hypothesis statements, MVPs for UX, and cross-functional collaboration. For Build-Measure-Learn, see lean-startup. For usability audits, see ux-heuristics.'
license: MIT
metadata:
  author: wondelai
  version: "1.4.0"
---

# Lean UX Framework

A practice-driven approach to UX that replaces heavy deliverables with rapid experimentation, cross-functional collaboration, and continuous learning. Lean UX shifts the question from "What should we design?" to "What do we need to learn?"

## Core Principle

**Outcomes over outputs.** The value of a design is measured not by the fidelity of the deliverable but by the change in user behavior it produces.

**The foundation:** Traditional UX waterfalls requirements into wireframes, mockups, specs, and code—losing context and hiding untested assumptions at every handoff. Lean UX compresses the distance between idea and evidence: declare assumptions, form hypotheses, run the smallest possible experiment, and let real user behavior settle the argument. Shared understanding replaces documentation; learning velocity replaces pixel perfection.

## Scoring

**Goal: 10/10.** Score a UX process, design plan, or team workflow by the eight-row Quick Diagnostic below: award ~1.25 points per row answered "yes" (8 yeses = 10). Bands:

- **9-10** — assumptions declared, hypotheses with pre-committed success criteria, lowest-fidelity experiments, whole-team design, weekly research, outcome (not output) metrics, dual-track agile, and a recently invalidated hypothesis on the books.
- **5-6** — hypotheses exist but criteria are vague or fidelity is over-invested; design and research still partly siloed.
- **<=3** — heavy deliverables, untested assumptions, output-counting, no experiment log.

Always state the current score, the diagnostic rows that failed, and the specific fix for each.

## Framework

### 1. Declaring Assumptions

**Core concept:** Every design starts with assumptions. Lean UX makes them explicit so they can be prioritized and tested, rather than baked invisibly into specifications.
```
END THIRD-PARTY FILE 2100ed5e32553f78

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