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lean-ux skill

by wondelai·wondelai/skills·2.3k stars·MIT

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.

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Install the lean-ux skill

A skill is a folder. Copy it into your agent's skills folder and the agent loads it when the task matches its description. 

git clone --depth 1 https://github.com/wondelai/skills.git /tmp/skills
mkdir -p ~/.claude/skills
cp -r /tmp/skills/lean-ux ~/.claude/skills/lean-ux
available in every project

In the Claude apps, zip the folder and upload it from the Skills settings. The folder on GitHub

The instructions your agent would load

SKILL.md as published, without the frontmatter. Read it on GitHub

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.

Why it works: Unspoken assumptions mean teams build on shaky ground and discover problems only after launch; surfacing them early focuses energy on the riskiest ones and reduces the cost of being wrong.

Key insights:

  • Business assumptions define what must be true for the business (revenue model, market size, willingness to pay); user assumptions define who users are and how they behave
  • Prioritize on two axes: risk (how damaging if wrong) and uncertainty (how little we know)
  • Test high-risk, high-uncertainty assumptions first
  • Write assumptions collaboratively as a team, not in isolation

Product applications:

Ethical boundary: Assumptions must be honest assessments, not post-hoc justifications—if leadership has already committed to a direction, acknowledge the constraint rather than pretending it's open to falsification.

See references/hypothesis-canvas.md when running an assumption workshop or writing a hypothesis — the risk/uncertainty prioritization matrix, business-vs-user assumption split, and fillable hypothesis and sub-hypothesis templates.

2. Hypothesis Statements

Core concept: A hypothesis translates an assumption into a testable prediction, linking a proposed change to a measurable outcome for a specific user segment.

Why it works: Hypotheses force precision—instead of "make onboarding better," the team commits to a prediction that can be proven or disproven, which prevents scope creep and makes the learn step unambiguous.

Key insights:

  • Standard format: "We believe [outcome] will happen if [persona] achieves [action] with [feature]"
  • Every hypothesis specifies persona, action, outcome, and measurable signal
  • Sub-hypotheses break a large bet into independently testable parts
  • Agree on what "validated" and "invalidated" look like before running the experiment

Product applications:

Ethical boundary: Never cherry-pick metrics after the fact to declare a hypothesis validated—pre-commit to success criteria.

See references/outcome-metrics.md when picking the measurable signal for a hypothesis or defining team success — outcomes-vs-outputs, leading-vs-lagging indicator pairs, UX OKRs, and the vanity metrics to avoid.

3. MVPs and Experiments

Core concept: An MVP in Lean UX is the smallest design artifact that can test a hypothesis with real users—a learning tool, not a product launch.

Why it works: A paper prototype tested with five users in a hallway can invalidate a hypothesis that would otherwise consume a full engineering sprint; matching experiment fidelity to assumption risk maximizes learning per unit of effort.

Key insights:

  • Experiments range from low fidelity (paper prototypes, concierge tests) to high fidelity (coded A/B tests, Wizard of Oz)
  • Choose the lowest-fidelity experiment that can answer the question
  • A good experiment has a clear hypothesis, defined audience, measurable signal, and time box
  • Proto-personas can stand in for full research when speed matters, but must be validated later

Product applications:

Ethical boundary: Smoke tests and fake doors must not mislead users into believing a product exists—disclose test status and offer an opt-out.

See references/experiment-patterns.md when choosing or designing an experiment — the full catalog of experiment types with when/when-NOT-to-run notes, the experiment selection matrix and fidelity ladder, and a design template.

4. Collaborative Design

Core concept: Design is a team sport. Lean UX replaces the solitary designer-then-handoff model with cross-functional sessions where developers, PMs, and designers sketch solutions together.

Why it works: Developers who helped sketch the solution don't need a 40-page spec to build it—shared understanding replaces documentation, diverse perspectives generate more creative solutions, and handoff waste drops dramatically.

Key insights:

  • Design Studio method: diverge (individual sketching), present, critique, converge (refined sketch), iterate
  • The goal is informed commitment, not consensus: the team agrees on what to test, not what is "right"
  • Cross-functional means engineers, QA, data analysts, and stakeholders sketch too
  • Style guides and pattern libraries are living documents; reduce deliverables to the minimum needed for shared understanding (often a whiteboard photo)

Product applications:

Ethical boundary: Collaboration must not become design by committee—a designated designer synthesizes input; the team does not vote on pixels.

See references/collaborative-design.md when facilitating a Design Studio — the step-by-step workshop protocol (timings, materials, remote variants) and how to keep style guides as living documents.

5. Feedback and Research

Core concept: Continuous, lightweight research replaces big-bang usability studies—small research activities embedded in every sprint instead of quarterly reports.

Why it works: Findings only change a decision while it is still cheap to reverse, so research value decays with every sprint between learning and the decision it informs; small weekly studies keep that gap near zero, which a quarterly report never can.

Key insights:

  • Research types: usability tests, customer interviews, A/B tests, analytics review, surveys, diary studies
  • Five users uncover approximately 85% of usability problems (Nielsen)
  • Continuous cadence: recruit weekly, test weekly, synthesize weekly
  • The whole team should observe at least some sessions to build empathy
  • Proto-personas are refined and eventually replaced by evidence-based personas

Product applications:

Ethical boundary: Conduct research with informed consent—participants should understand how their data is used and be free to withdraw.

6. Integration with Agile

Core concept: Lean UX works inside Agile via dual-track development: discovery (learning what to build) and delivery (building it) run in parallel.

Why it works: Design work doesn't fit neatly into a delivery sprint; running discovery one sprint ahead means validated designs are ready when the delivery sprint begins, instead of design forever catching up.

Key insights:

  • The discovery track (research + design) feeds the delivery track (engineering + QA), staggered one sprint ahead
  • User stories gain a hypothesis and success metric alongside acceptance criteria
  • "Definition of Done" for UX includes validated learning, not just shipped pixels
  • Backlog items from invalidated hypotheses are removed, not deferred

Product applications:

Ethical boundary: Never use Lean UX as an excuse to skip accessibility, security, or compliance—these are non-negotiable quality standards, not assumptions to test.

See references/agile-integration.md when fitting discovery into a delivery cadence — the staggered dual-track sprint mechanics, how stories carry a hypothesis, and a UX Definition of Done.

See references/case-studies.md when you want a worked end-to-end example to model an engagement on — four composite scenarios (enterprise, startup, agency, internal tools) showing assumptions, experiments, and before/after outcome metrics.

Common Mistakes

Quick Diagnostic

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