app-builder

app-builder is a skill for Claude Code from Ghosteken/agent-harness. It costs 29 tokens per session (857 once invoked), scanned A, a copy of app-builder, MIT.

An application-building coordinator that turns a natural-language request into a planned full-stack application, meaning an app with both its user interface and server-side parts.

In plain words
What is it for?
It helps create new applications, select a suitable technology stack, scaffold project files, and coordinate work across development tasks.
Why use it?
It helps organize technology choices, project structure, templates, and development tasks when starting or extending an application.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the agent-harness plugin — 173 skills, 11 commands, 12 agents shipped together

Good fit It helps create new applications, select a suitable technology stack, scaffold project files, and coordinate work across development tasks.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/ghosteken/agent-harness/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 Ghosteken/agent-harness --skill app-builder
Clone the repo
git clone --depth 1 https://github.com/Ghosteken/agent-harness

Made for: Claude Code.

Or install agent-harness, the plugin that ships this one along with the rest of its 173 skills, 11 commands, 12 agents.

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 app-builder

README.md
[![agentmods](https://agentmods.dev/badge/skills/ghosteken/agent-harness/app-builder/github.svg)](https://agentmods.dev/skills/ghosteken/agent-harness/app-builder)
Your own site
<a href="https://agentmods.dev/skills/ghosteken/agent-harness/app-builder"><img src="https://agentmods.dev/badge/skills/ghosteken/agent-harness/app-builder/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.

agentmods 80×15 button for app-builder

Your own site · 80×15
<a href="https://agentmods.dev/skills/ghosteken/agent-harness/app-builder"><img src="https://agentmods.dev/badge/skills/ghosteken/agent-harness/app-builder.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 29 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 857 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 94% copy Near-identical to another mod 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 $0.00029 $0.00857
Opus 5 $0.00015 $0.00428
Sonnet 5 $0.00006 $0.00171
Haiku 4.5 $0.00003 $0.00086

Measured 6d ago against content hash 094248078172, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

app-builder 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 6d 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.

Origin

This is a copy

94% identical to app-builder — 2 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.

archive/skills-community/app-builder/SKILL.md · 86 lines

How it starts

The opening of the file, as written. The whole thing — 86 lines — stays where its author put it; the contents beside it link to each section on GitHub.

App Builder - Application Building Orchestrator

Analyzes user's requests, determines tech stack, plans structure, and coordinates agents.

🎯 Selective Reading Rule

Read ONLY files relevant to the request! Check the content map, find what you need.

File Description When to Read
project-detection.md Keyword matrix, project type detection Starting new project
tech-stack.md 2025 default stack, alternatives Choosing technologies
agent-coordination.md Agent pipeline, execution order Coordinating multi-agent work
scaffolding.md Directory structure, core files Creating project structure
feature-building.md Feature analysis, error handling Adding features to existing project
templates/SKILL.md Project templates Scaffolding new project

📦 Templates (13)

Quick-start scaffolding for new projects. Read the matching template only!

Template Tech Stack When to Use
nextjs-fullstack Next.js + Prisma Full-stack web app
nextjs-saas Next.js + Stripe SaaS product
nextjs-static Next.js + Framer Landing page
nuxt-app Nuxt 3 + Pinia Vue full-stack app
express-api Express + JWT REST API
python-fastapi FastAPI Python API
react-native-app Expo + Zustand Mobile app
flutter-app Flutter + Riverpod Cross-platform mobile
electron-desktop Electron + React Desktop app
chrome-extension Chrome MV3 Browser extension
cli-tool Node.js + Commander CLI app
monorepo-turborepo Turborepo + pnpm Monorepo

Read the full file on GitHub · 86 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. 6d ago First seen · 86 lines · 29 tokens per session scan A 094248078172

Subscribe to this mod's changes

app-builder is a skill published in the GitHub repository Ghosteken/agent-harness (2 stars, last pushed 5d ago), licensed MIT. It adds 29 tokens to every session and 857 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 94% identical to app-builder, differing in 2 lines, and is treated as a copy.