AG Kit is a toolkit that gives Google Antigravity coding agents a structured workspace with rules, skills, specialist agents, workflows, persistent memory, orchestration, MCP guidance, and a safety hook. It is for building and operating agent workflows in Antigravity, and its catalogue entries provide parts of that workspace contract.
Borrowing it
Nothing to install: this file belongs to vudovn/ag-kit. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/vudovn/ag-kit/main/.agents/skills/app-builder/SKILL.mdgit clone --depth 1 https://github.com/vudovn/ag-kitWrote 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.
[](https://agentmods.dev/skills/vudovn/ag-kit/app-builder)<a href="https://agentmods.dev/skills/vudovn/ag-kit/app-builder"><img src="https://agentmods.dev/badge/skills/vudovn/ag-kit/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.
<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="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00029 | $0.00843 |
| Opus 5.5 | $0.00012 | $0.00337 |
| Sonnet 5.5 | $0.00006 | $0.00169 |
| Haiku 4.5 | $0.00003 | $0.00084 |
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 1mo 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.
This is a copy
83% identical to app-builder — 23 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.
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 |
What ships with it
19 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.
- agent-coordination.md 6.7 KB
- feature-building.md 1.3 KB
- project-detection.md 2.4 KB
- scaffolding.md 3.9 KB
- tech-stack.md 1.7 KB
- templates/astro-static/TEMPLATE.md 2.1 KB
- templates/chrome-extension/TEMPLATE.md 2.7 KB
- templates/cli-tool/TEMPLATE.md 2.4 KB
- templates/electron-desktop/TEMPLATE.md 2.7 KB
- templates/express-api/TEMPLATE.md 2.4 KB
- templates/flutter-app/TEMPLATE.md 2.1 KB
- templates/monorepo-turborepo/TEMPLATE.md 2.6 KB
- templates/nextjs-fullstack/TEMPLATE.md 4.3 KB
- templates/nextjs-saas/TEMPLATE.md 3.6 KB
- templates/nextjs-static/TEMPLATE.md 5.7 KB
- templates/nuxt-app/TEMPLATE.md 3.9 KB
- templates/python-fastapi/TEMPLATE.md 2.7 KB
- templates/react-native-app/TEMPLATE.md 4.6 KB
- templates/SKILL.md 1.6 KB
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.
- 1mo ago Changed 1e720200afac
- 1mo ago First seen · 79 lines · 29 tokens per session scan A 567a69668c38
app-builder is a skill published in the GitHub repository vudovn/ag-kit (8,199 stars, last pushed 3d ago), licensed MIT. It adds 29 tokens to every session and 843 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 83% identical to app-builder, differing in 23 lines, and is treated as a copy.
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