app-builder

An application-building coordinator that turns a natural-language request into a full-stack application. It identifies the project type, chooses technologies, plans the structure, and coordinates other agents.

In plain words
What is it for?
Use it to start a new application, choose a suitable technology stack, scaffold a project from a template, or add features to an existing project.
Why use it?
It provides a starting point for building an application without manually deciding every project setup and implementation step. Full-stack means the application includes both its user interface and server-side parts.

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

Made for: Claude Code, Codex.

Per session 29 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 757 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 83% 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 $0.00029 $0.00757
Opus 5 $0.00015 $0.00378
Sonnet 5 $0.00006 $0.00151
Haiku 4.5 $0.00003 $0.00076

Measured yesterday against content hash c23b2491d71a, 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 yesterday.

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

83% identical to app-builder — 8 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.

.opencode/skills/app-builder/SKILL.md · 75 lines

How it starts

The opening of the file, as written. The whole thing — 75 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 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 · 75 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. yesterday First seen · 75 lines · 29 tokens per session scan A c23b2491d71a

Subscribe to this mod's changes

app-builder is a skill published in the GitHub repository felipeslo/opencode-kit (2 stars, last pushed 5mo ago), licensed MIT. It adds 29 tokens to every session and 757 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 83% identical to app-builder, differing in 8 lines, and is treated as a copy.

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