web-app-builder

web-app-builder is a skill for Claude Code, Codex from archimedes-run/omniHarness. It costs 42 tokens per session (1,679 once invoked), scanned C, original, MIT.

A tool for building previewable websites, web applications, dashboards, and other browser-based projects as managed artifacts. It separates the source project from the exported preview and records how the artifact should be opened.

In plain words
What is it for?
Use it to create a website, dashboard, landing page, frontend prototype, or browser app with source files, preview output, and an artifact manifest.
Why use it?
It provides a consistent project layout and metadata so the result can be previewed and handed off. It supports both static files and running applications.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to create a website, dashboard, landing page, frontend prototype, or browser app with source files, preview output, and an artifact manifest.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/archimedes-run/omniharness/web-app-builder
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.

Any agent
npx skills add archimedes-run/omniHarness --skill web-app-builder
Clone the repo
git clone --depth 1 https://github.com/archimedes-run/omniHarness

Made for: Claude Code, Codex.

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 web-app-builder

README.md
[![agentmods](https://agentmods.dev/badge/skills/archimedes-run/omniharness/web-app-builder.svg)](https://agentmods.dev/skills/archimedes-run/omniharness/web-app-builder)
Your own site
<a href="https://agentmods.dev/skills/archimedes-run/omniharness/web-app-builder"><img src="https://agentmods.dev/badge/skills/archimedes-run/omniharness/web-app-builder.svg" alt="Measured on agentmods" height="20"></a>
Per session 42 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,679 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 1 finding. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00042 $0.01679
Opus 5 $0.00021 $0.00839
Sonnet 5 $0.00008 $0.00336
Haiku 4.5 $0.00004 $0.00168

Measured 7d ago against content hash 41f432765bdc, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade C, and why

web-app-builder scanned grade C 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 7d 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.

Recursive force deletehighDestructive command

rm -rf with a variable or a broad path is one typo away from removing the wrong tree.

rm -rf /mnt/user-data/outputs/my-vite-app
skills/public/web-app-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.

Web App Builder

Use this skill when the user asks to create a website, web app, dashboard, landing page, frontend prototype, or browser-based artifact that should be previewable in OmniHarness.

Artifact Layout

Always separate source code from exported artifacts:

  • Source projects go under /mnt/user-data/workspace/<artifact_id>.
  • Static preview outputs go under /mnt/user-data/outputs/<artifact_id>.
  • Dynamic project manifests still live under /mnt/user-data/outputs/<artifact_id>/artifact_manifest.json even when the running app stays in workspace.
  • Every website, dashboard, or app artifact must include /mnt/user-data/outputs/<artifact_id>/artifact_manifest.json.

Use a stable, lowercase artifact_id such as sales-dashboard, omniharness-next-site, or research-portal.

Required Manifest

Create this file in the output root for static sites:

{
  "id": "artifact-id",
  "title": "Human Friendly Project Title",
  "type": "static_site",
  "entrypoint": "index.html",
  "root": ".",
  "source_path": "/mnt/user-data/workspace/artifact-id",
  "preview": {
    "mode": "static"
  },
  "created_by": "agent"
}

Field reference — use exactly these key names:

Field Required Notes
id yes Lowercase kebab-case. Must match the output folder name.
title yes Human-readable display name. NOT name — use title.
type yes "static_site" or "web_app".
root yes Relative path to the served root. Use "." for the output folder itself.
entrypoint static only Path to index.html relative to root. Required for static_site.
source_path web_app only Absolute workspace path of the project. Top-level field, NOT inside preview.
preview.mode yes "static" for static sites, "dev_server" for dynamic apps.
preview.command web_app only Dev-server start command, e.g. "npm run dev -- --hostname 0.0.0.0".
preview.port web_app only Port the dev server binds on, e.g. 3000.
created_by no Set to "agent".

Read the full file on GitHub · 171 lines

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. 7d ago First seen · 171 lines · 42 tokens per session scan C 41f432765bdc

Subscribe to this mod's changes

web-app-builder is a skill published in the GitHub repository archimedes-run/omniHarness (7 stars, last pushed 12d ago), licensed MIT. It adds 42 tokens to every session and 1,679 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it C with 1 finding (recursive force delete). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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