Spree is a self-hostable, open-source commerce platform for building online stores, B2B systems, and multi-vendor marketplaces. It provides a commerce backend with a REST API, TypeScript SDK, administration interface, and Next.js storefront. The catalogue add-ons teach coding agents how to customize, operate, and upgrade Spree projects.
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.
npx skills add spree/spree --skill prototypegit clone --depth 1 https://github.com/spree/spreeWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/spree/spree/prototype)<a href="https://agentmods.dev/skills/spree/spree/prototype"><img src="https://agentmods.dev/badge/skills/spree/spree/prototype/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/spree/spree/prototype"><img src="https://agentmods.dev/badge/skills/spree/spree/prototype.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00048 | $0.01634 |
| Opus 5 | $0.00024 | $0.00817 |
| Sonnet 5 | $0.00010 | $0.00327 |
| Haiku 4.5 | $0.00005 | $0.00163 |
Grade A, and why
prototype 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 12d 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.
This is a copy
100% identical to prototype — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 91 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Prototyping Variants
A divergence skill. It does ONE thing: take a described piece of UI ("a toast", "the pricing card", "a hold-to-delete button"), build several genuinely different versions of it, and put them behind a visual picker so the user can flip through them live and choose a winner. It does not review existing UI (that's review-animations), plan fixes for it (that's improve-animations), or choose dependencies (that's pick-ui-library).
Operating Posture
You are a senior design engineer running a design exploration. The entire value of this skill is divergence: three tints of the same idea waste the picker — the user learns nothing by flipping between them. Each variant must be a direction you could defend shipping on its own, exploring a genuinely different answer to the same brief.
Divergence is not an excuse to drop the craft bar. Every variant individually meets Emil Kowalski's standards — right easing (ease-out on entrances, never ease-in), sub-300ms UI motion, correct transform-origin, transform/opacity only, reduced-motion handled. A sloppy variant doesn't widen the exploration; it just loses on execution and teaches nothing about the direction it represents.
Hard Rules
- Never touch production code during exploration. Everything lives in an isolated prototype surface (see Phase 4). Integration happens only in Phase 6, only for the variant the user picked.
- Variants diverge on a named axis — layout, density, personality, motion, interaction model. Before building, you must be able to state each variant's axis in a phrase. Sharing the project's tokens is not convergence; variants should feel native to the product.
- Every variant fully works. Real interactions, real motion, realistic content — actual product-shaped copy, plausible names and numbers. No lorem ipsum, no dead buttons, no "imagine this part".
- The picker is chrome, not a contestant. Its exact markup, styles, and behavior are specified in PICKER.md — copy them verbatim. Its look is not a design decision and never adapts to the project.
- Clean up after the choice. When a winner is promoted, delete the prototype surface unless the user asks to keep it.
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 12d ago First seen · 91 lines · 48 tokens per session scan A 2ad8401c4dea
prototype is a skill published in the GitHub repository spree/spree (15,688 stars, last pushed today), licensed BSD-3-Clause. It adds 48 tokens to every session and 1,634 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to prototype, differing in 0 lines, and is treated as a copy.
Other skills, from other repositories
design-tokens-transformer
A converter for design tokens, which are named values for colors, fonts, spacing, borders, shadows, and motion. It translates one shared token source into CSS variables and Tailwind or shadcn-style theme files, and can convert them back for checking.
design-brand-system
A visual design-system guide for branded web projects. It defines reusable choices such as colors, typography, spacing, components, and design tokens, while checking contrast and other accessibility requirements.
design-landing-motion
A workflow for building animated landing pages, including page concepts, visual assets, and scroll-based effects such as parallax or 3D motion.
design-gui-guide
A practical guide to using common interface parts such as buttons, forms, menus, links, dialogs, alerts, tabs, and search.
design-workflow
A workflow for bringing design handoff files, design tokens, and project design briefs into a code project. It validates the tokens and loads research, system, and specification notes before interface implementation.
doc-design-library
A pointer to a library of 75 brand design systems, each defining choices such as colors, typefaces, spacing, corner shapes, and interface components. It applies those design rules to single-file HTML reports and slide decks.