prototype-lab

A design exercise that creates three clearly different HTML, CSS, and JavaScript website prototypes from the same product research and sample data. After one is chosen, it records the approved design direction for the product.

In plain words
What is it for?
Exploring three design directions, reviewing the same core flows in each, choosing one, and saving its visual and brand decisions in the product documentation.
Why use it?
It lets people compare brand, layout, wording, and user-flow ideas before writing the product plan. Using the same sample data keeps the comparison focused on design rather than changing content.

Skill for Claude CodeCodex

Part of the ai-dev-operating-system plugin — 28 skills, 11 commands, 12 agents, 1 hook shipped together

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/lglucas/ai-dev-operating-system/prototype-lab
Any agent
npx skills add lglucas/ai-dev-operating-system --skill prototype-lab
Clone the repo
git clone --depth 1 https://github.com/lglucas/ai-dev-operating-system

Made for: Claude Code, Codex.

Or install ai-dev-operating-system, the plugin that ships this one along with the rest of its 28 skills, 11 commands, 12 agents, 1 hook.

Per session 114 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 432 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00114 $0.00432
Opus 5 $0.00057 $0.00216
Sonnet 5 $0.00023 $0.00086
Haiku 4.5 $0.00011 $0.00043

Measured 3d ago against content hash 989ce6089df0, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

prototype-lab scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/skills/prototype-lab/SKILL.md · 29 lines

What it actually says

Prototype Lab Skill

Create three distinct HTML/CSS/JS prototype directions using the same mock data.

Runs at Phase 3 of WIZARD.md — before the Product Brief and the Technical Plan, not after.

Inputs

All prototypes must reflect BP v0.0.2 (personas, positioning, MVP scope, primary flow) and the research in knowledge-base/.

The Product Brief is NOT an input. It does not exist yet — Phase 4 derives it from the direction approved here. If you find yourself needing the Product Brief, the thing you actually need is missing from BP v0.0.2; go add it there.

Rules

  • Three directions, genuinely distinct — not three shades of one idea.
  • All three read the same file: prototype-lab/shared/mock-data.js. Not "equivalent data" — the same file. Phase 4.2 derives the Technical Plan's entities from it, so it needs one guaranteed shared source.
  • Same core flows across all three, so the comparison is about design and not content.
  • Each direction carries an explicit brand hypothesis: palette, typography, density, tone.
  • Do not contaminate the production app with prototype code.

Output

After the user picks a direction, write docs/product/DESIGN-DIRECTION.md — tokens, typography scale, spacing, component inventory, screens, the flow as actually clicked, and what was rejected. That file is what Phase 4 reads.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago First seen · 29 lines · 114 tokens per session scan A 989ce6089df0

Subscribe to this mod's changes

prototype-lab is a skill published in the GitHub repository lglucas/ai-dev-operating-system (11 stars, last pushed 24d ago), licensed MIT. It adds 114 tokens to every session and 432 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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