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/nextjs-react-expert/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/nextjs-react-expert)<a href="https://agentmods.dev/skills/vudovn/ag-kit/nextjs-react-expert"><img src="https://agentmods.dev/badge/skills/vudovn/ag-kit/nextjs-react-expert/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/nextjs-react-expert"><img src="https://agentmods.dev/badge/skills/vudovn/ag-kit/nextjs-react-expert.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 | $0.00048 | $0.02445 |
| Opus 5.5 | $0.00019 | $0.00978 |
| Sonnet 5.5 | $0.00010 | $0.00489 |
| Haiku 4.5 | $0.00005 | $0.00245 |
Grade A, and why
nextjs-react-expert 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.
Copies of this mod
3 near-identical copies found in the catalogue:
- nextjs-react-expert — 91% identical, 78 lines differ
- react-best-practices — 91% identical, 23 lines differ
- nextjs-react-expert — 91% identical, 78 lines differ
How it starts
The opening of the file, as written. The whole thing — 294 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Next.js & React Performance Expert
From Vercel Engineering - 58 optimization rules prioritized by impact, plus Next.js 16 Cache Components Philosophy: Eliminate waterfalls first, optimize bundles second, then micro-optimize.
🎯 Selective Reading Rule (MANDATORY)
Read ONLY sections relevant to your task! Check the content map below and load what you need.
🔴 For performance reviews: Start with CRITICAL sections (1-2), then move to HIGH/MEDIUM.
📑 Content Map
| File | Impact | Rules | When to Read |
|---|---|---|---|
1-async-eliminating-waterfalls.md |
🔴 CRITICAL | 6 rules | Slow page loads, sequential API calls, data fetching waterfalls |
2-bundle-bundle-size-optimization.md |
🔴 CRITICAL | 5 rules | Large bundle size, slow Time to Interactive, First Load issues |
3-server-server-side-performance.md |
🟠 HIGH | 7 rules | Slow SSR, API route optimization, server-side waterfalls |
4-client-client-side-data-fetching.md |
🟡 MEDIUM-HIGH | 4 rules | Client data management, SWR patterns, deduplication |
5-rerender-re-render-optimization.md |
🟡 MEDIUM | 12 rules | Excessive re-renders, React performance, memoization |
6-rendering-rendering-performance.md |
🟡 MEDIUM | 9 rules | Rendering bottlenecks, virtualization, image optimization |
7-js-javascript-performance.md |
⚪ LOW-MEDIUM | 12 rules | Micro-optimizations, caching, loop performance |
8-advanced-advanced-patterns.md |
🔵 VARIABLE | 3 rules | Advanced React patterns, useLatest, init-once |
9-cache-components.md |
🔴 CRITICAL | 4 sections | Next.js 16+ Only: use cache, cacheLife, PPR, cacheTag |
What ships with it
11 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.
- 1-async-eliminating-waterfalls.md 8.6 KB
- 2-bundle-bundle-size-optimization.md 6.1 KB
- 3-server-server-side-performance.md 13 KB
- 4-client-client-side-data-fetching.md 6.7 KB
- 5-rerender-re-render-optimization.md 15 KB
- 6-rendering-rendering-performance.md 10 KB
- 7-js-javascript-performance.md 17 KB
- 8-advanced-advanced-patterns.md 3.6 KB
- 9-cache-components.md 2.8 KB
- scripts/convert_rules.py 6.5 KB runs code
- scripts/react_performance_checker.py 11 KB runs code
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 First seen · 294 lines · 48 tokens per session scan A 1db0736663af
nextjs-react-expert is a skill published in the GitHub repository vudovn/ag-kit (8,199 stars, last pushed 3d ago), licensed MIT. It adds 48 tokens to every session and 2,445 once invoked, about $0.0002 per session on Opus 5.5. 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.
Other skills, from other repositories
chakra-ui-builder
Build responsive, accessible UI components and layouts using Chakra UI v3, install or configure Chakra UI in new and existing projects, and design scalable themes using tokens, semantic tokens, recipes, and slot recipes. Use this skill whenever a user asks to build, create, or generate any UI component, page, form…
material-ui-tailwind
Integrates Material UI with Tailwind CSS v4 using cascade layers (enableCssLayer, @layer order) and documents Tailwind v3 interoperability (preflight, important, injectFirst, portals). Use when combining MUI with Tailwind utilities, slotProps className, or theme token bridges.
fuzzy-ranking
Rank fuzzy matches with rankItem, filter with RankingInfo.passed, compare saved ranking metadata with compareItems, and configure rankings, thresholds, accessors, min/max bounds, or diacritics. Load for @tanstack/match-sorter-utils itself or fuzzy Table filterMeta wiring.
r3f-best-practices
React Three Fiber (R3F) and Poimandres ecosystem best practices. Use when writing, reviewing, or optimizing R3F code. Triggers on tasks involving @react-three/fiber, @react-three/drei, zustand, @react-three/postprocessing, @react-three/rapier, or leva.
git-safety
Git safety rules. INVOKE WHEN: git push, force push, git reset, git clean, destructive git, push force, reset hard. NEVER force push or do destructive git operations.
onchainkit
Build onchain apps with Coinbase's OnchainKit React components - wallets, swaps, NFTs, payments.