app-builder

app-builder is a skill for Claude Code, Codex from vudovn/ag-kit. It costs 29 tokens per session (843 once invoked), scanned A, original, MIT.

A planning and coordination guide for creating full-stack applications from plain-language requests. Full-stack means the application’s user interface and its server-side code are built together.

In plain words
What is it for?
Starting applications, selecting a project template, creating the initial structure, choosing technologies, and adding features to an existing project.
Why use it?
It helps decide what kind of project is being requested, choose a technology stack, organize the files, and coordinate the work needed to build features.

Skill for Claude CodeCodex

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/vudovn/ag-kit/app-builder
Any agent
npx skills add vudovn/ag-kit --skill app-builder
Clone the repo
git clone --depth 1 https://github.com/vudovn/ag-kit

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 app-builder

README.md
[![agentmods](https://agentmods.dev/badge/skills/vudovn/ag-kit/app-builder.svg)](https://agentmods.dev/skills/vudovn/ag-kit/app-builder)
Your own site
<a href="https://agentmods.dev/skills/vudovn/ag-kit/app-builder"><img src="https://agentmods.dev/badge/skills/vudovn/ag-kit/app-builder.svg" alt="Measured on agentmods" 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 843 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 $0.00029 $0.00843
Opus 5 $0.00015 $0.00421
Sonnet 5 $0.00006 $0.00169
Haiku 4.5 $0.00003 $0.00084

Measured 3d ago against content hash 1e720200afac, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, 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 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.

Origin

Copies of this mod

8 near-identical copies found in the catalogue:

.agents/skills/app-builder/SKILL.md · 79 lines

How it starts

The opening of the file, as written. The whole thing — 79 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 2026 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 4 + 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
astro-static Astro + MDX Blog / Documentation

Read the full file on GitHub · 79 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. 3d ago Changed 1e720200afac
  2. 4d ago First seen · 79 lines · 29 tokens per session scan A 567a69668c38

Subscribe to this mod's changes

app-builder is a skill published in the GitHub repository vudovn/ag-kit (8,168 stars, last pushed 4d ago), licensed MIT. It adds 29 tokens to every session and 843 once invoked, about $0.0001 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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