genui-builder

genui-builder is a skill for Claude Code, Codex from mindverse-ltd/macaron-artifacts. It costs 91 tokens per session (2,043 once invoked), scanned A, original, Apache-2.0.

A skill for creating web interfaces in TSX or HTML that update as model output streams in. TSX is a format for writing user-interface components with TypeScript and JSX, and the results are designed for Macaron previews.

In plain words
What is it for?
Use it to create streaming user interfaces, standalone HTML from TSX, visual previews, and browser runtimes that display model-generated UI as it arrives.
Why use it?
It helps avoid waiting for a complete interface before showing it, so you can see incremental updates during generation.

Skill for Claude CodeCodex

Part of the macaron plugin — 5 skills, 1 command 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/mindverse-ltd/macaron-artifacts/genui-builder
Any agent
npx skills add mindverse-ltd/macaron-artifacts --skill genui-builder
Clone the repo
git clone --depth 1 https://github.com/mindverse-ltd/macaron-artifacts

Made for: Claude Code, Codex.

Or install macaron, the plugin that ships this one along with the rest of its 5 skills, 1 command.

Wrote 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.

agentmods badge for genui-builder

README.md
[![agentmods](https://agentmods.dev/badge/skills/mindverse-ltd/macaron-artifacts/genui-builder.svg)](https://agentmods.dev/skills/mindverse-ltd/macaron-artifacts/genui-builder)
Your own site
<a href="https://agentmods.dev/skills/mindverse-ltd/macaron-artifacts/genui-builder"><img src="https://agentmods.dev/badge/skills/mindverse-ltd/macaron-artifacts/genui-builder.svg" alt="Measured on agentmods" height="20"></a>
Per session 91 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,043 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. 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 $0.00091 $0.02043
Opus 5 $0.00046 $0.01022
Sonnet 5 $0.00018 $0.00409
Haiku 4.5 $0.00009 $0.00204

Measured 4d ago against content hash 0ca268d864f5, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

genui-builder scanned grade A with 1 finding 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 4d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

If the `mcp__macaron.render_ui` tool is exposed to you, call it directly with the complete TSX module in its `code` field — the host mounts the component inline in the conversation. The tool's own description already car
skills/genui-builder/SKILL.md · 171 lines

How it starts

The opening of the file, as written. The whole thing — 171 lines — stays where its author put it; the contents beside it link to each section on GitHub.

GenUI Builder

Use this skill to produce streaming GenUI App.tsx/HTML artifacts. Default to streaming model output and incremental preview refresh; do not build one-shot "wait for full TSX, then render" experiences unless the user explicitly asks for non-streaming output.

Preferred path: render_ui MCP tool

If the mcp__macaron.render_ui tool is exposed to you, call it directly with the complete TSX module in its code field — the host mounts the component inline in the conversation. The tool's own description already carries the authoring rules for $macaron/ui, streaming write order, and quality constraints. Do NOT curl anything or emit markdown TSX fences when this tool is available.

Local authoring rules (fallback)

If render_ui is not exposed (older host or a bare CLI), fall back to writing a self-contained TSX module and use the CLI below to validate or render it. Detailed constraints and common fixes are in references/tsx-output.md.

Optionally, if the runtime allows network egress, you MAY fetch the canonical live authoring prompt for cross-check — but only if you already have a specific ambiguity to resolve. Do NOT fetch it prophylactically before every render:

curl -fsSL https://genui.macaron.im/api/system-prompt

If that command errors (DNS blocked, no network, non-2xx), silently proceed with the local rules — do not surface the failure to the user.

CLI

The CLI is optional. Prefer direct streaming runtimes when the user wants an HTML harness or GenUI capability inside a page. Use the CLI for validation, standalone one-shot export, or when the user explicitly asks for the CLI.

Use this exact pinned command unless the user provides a newer one:

bunx genui@https://pkg.pr.new/MindLab-Research/macaron-genui-demo/@genui/cli@00b6767

The CLI supports:

bunx genui@https://pkg.pr.new/MindLab-Research/macaron-genui-demo/@genui/cli@00b6767 lint App.tsx
bunx genui@https://pkg.pr.new/MindLab-Research/macaron-genui-demo/@genui/cli@00b6767 check App.tsx
bunx genui@https://pkg.pr.new/MindLab-Research/macaron-genui-demo/@genui/cli@00b6767 build App.tsx -o index.html
bunx genui@https://pkg.pr.new/MindLab-Research/macaron-genui-demo/@genui/cli@00b6767 dev App.tsx -p 4173 --host 127.0.0.1

Read the full file on GitHub · 171 lines

Files

What ships with it

2 files 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.

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. 4d ago First seen · 171 lines · 91 tokens per session scan A 0ca268d864f5

Subscribe to this mod's changes

genui-builder is a skill published in the GitHub repository mindverse-ltd/macaron-artifacts (10 stars, last pushed 12d ago), licensed Apache-2.0. It adds 91 tokens to every session and 2,043 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Related

Other skills, from other repositories