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.
npx skills add smicolon/ai-kit --skill vercel-react-best-practicesgit clone --depth 1 https://github.com/smicolon/ai-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/smicolon/ai-kit/vercel-react-best-practices)<a href="https://agentmods.dev/skills/smicolon/ai-kit/vercel-react-best-practices"><img src="https://agentmods.dev/badge/skills/smicolon/ai-kit/vercel-react-best-practices.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00053 | $0.01562 |
| Opus 5 | $0.00026 | $0.00781 |
| Sonnet 5 | $0.00011 | $0.00312 |
| Haiku 4.5 | $0.00005 | $0.00156 |
Grade A, and why
vercel-react-best-practices 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 2d 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.
How it starts
The opening of the file, as written. The whole thing — 181 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Vercel React Best Practices
Comprehensive performance optimization guide for React and Next.js applications, maintained by Vercel Engineering. Contains rules across 8 categories, prioritized by impact to guide automated refactoring and code generation.
Rule Categories by Priority
| Priority | Category | Impact | Prefix | Focus |
|---|---|---|---|---|
| 1 | Eliminating Waterfalls | CRITICAL | async- |
Parallel fetches, deferred awaits, Suspense streaming |
| 2 | Bundle Size Optimization | CRITICAL | bundle- |
Direct imports over barrel files, dynamic imports, conditional loading |
| 3 | Server-Side Performance | HIGH | server- |
React.cache(), non-blocking after(), data minimization |
| 4 | Client-Side Data Fetching | MEDIUM-HIGH | client- |
SWR / TanStack Query, optimistic UI, caching |
| 5 | Re-render Optimization | MEDIUM | rerender- |
Reference stability, context splitting, derived state |
| 6 | Rendering Performance | MEDIUM | rendering- |
Virtualization, content-visibility, memoization |
| 7 | JavaScript Performance | LOW-MEDIUM | js- |
Algorithmic efficiency, avoiding work in render |
| 8 | Advanced Patterns | LOW | advanced- |
Islands, partial hydration, micro-optimizations |
1. Eliminating Waterfalls (CRITICAL)
async-defer-await
Move await into the exact branches where the value is needed, not at the top of functions:
// ❌ WRONG: Blocks execution even if user branch is never hit
async function handleRequest(userId?: string) {
const user = userId ? await fetchUser(userId) : null
if (!user) return redirect('/login')
return renderProfile(user)
}
// ✅ CORRECT: Start early or await inside condition
async function handleRequest(userId?: string) {
if (!userId) return redirect('/login')
const user = await fetchUser(userId)
return renderProfile(user)
}
async-parallel
Use Promise.all() for independent asynchronous operations:
// ❌ WRONG: Sequential waterfall (takes T1 + T2)
const user = await fetchUser(id)
const posts = await fetchPosts(id)
// ✅ CORRECT: Concurrent fetches (takes max(T1, T2))
const [user, posts] = await Promise.all([
fetchUser(id),
fetchPosts(id),
])
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.
- 2d ago First seen · 181 lines · 53 tokens per session scan A 5bfea8e44455
vercel-react-best-practices is a skill published in the GitHub repository smicolon/ai-kit (6 stars, last pushed 3d ago), licensed MIT. It adds 53 tokens to every session and 1,562 once invoked, about $0.0003 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 2026-09-04.
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