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 georgekhananaev/claude-skills-vault --skill react-best-practicesgit clone --depth 1 https://github.com/georgekhananaev/claude-skills-vaultWrote 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/georgekhananaev/claude-skills-vault/react-best-practices)<a href="https://agentmods.dev/skills/georgekhananaev/claude-skills-vault/react-best-practices"><img src="https://agentmods.dev/badge/skills/georgekhananaev/claude-skills-vault/react-best-practices/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/georgekhananaev/claude-skills-vault/react-best-practices"><img src="https://agentmods.dev/badge/skills/georgekhananaev/claude-skills-vault/react-best-practices.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00065 | $0.01762 |
| Opus 5.5 | $0.00026 | $0.00705 |
| Sonnet 5.5 | $0.00013 | $0.00352 |
| Haiku 4.5 | $0.00006 | $0.00176 |
Grade A, and why
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 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
97% identical to react-performance — 5 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 — 150 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. Contains 70 rules across 8 categories, prioritized by impact to guide automated refactoring and code generation.
When to Apply
Reference these guidelines when:
- Writing new React components or Next.js pages
- Implementing data fetching (client or server-side)
- Reviewing code for performance issues
- Refactoring existing React/Next.js code
- Optimizing bundle size or load times
Rule Categories by Priority
| Priority | Category | Impact | Prefix |
|---|---|---|---|
| 1 | Eliminating Waterfalls | CRITICAL | async- |
| 2 | Bundle Size Optimization | CRITICAL | bundle- |
| 3 | Server-Side Performance | HIGH | server- |
| 4 | Client-Side Data Fetching | MEDIUM-HIGH | client- |
| 5 | Re-render Optimization | MEDIUM | rerender- |
| 6 | Rendering Performance | MEDIUM | rendering- |
| 7 | JavaScript Performance | LOW-MEDIUM | js- |
| 8 | Advanced Patterns | LOW | advanced- |
Quick Reference
1. Eliminating Waterfalls (CRITICAL)
async-cheap-condition-before-await- Check cheap sync conditions before awaiting flags or remote valuesasync-defer-await- Move await into branches where actually usedasync-parallel- Use Promise.all() for independent operationsasync-dependencies- Use better-all for partial dependenciesasync-api-routes- Start promises early, await late in API routesasync-suspense-boundaries- Use Suspense to stream content
2. Bundle Size Optimization (CRITICAL)
bundle-barrel-imports- Import directly, avoid barrel filesbundle-analyzable-paths- Prefer statically analyzable import and file-system paths to avoid broad bundles and tracesbundle-dynamic-imports- Use next/dynamic for heavy componentsbundle-defer-third-party- Load analytics/logging after hydrationbundle-conditional- Load modules only when feature is activatedbundle-preload- Preload on hover/focus for perceived speed
What ships with it
60 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.
- AGENTS.md 66 KB
- rules/_sections.md 1.6 KB
- rules/_template.md 659 B
- rules/advanced-effect-event-deps.md 1.8 KB
- rules/advanced-event-handler-refs.md 1.5 KB
- rules/advanced-init-once.md 958 B
- rules/advanced-use-latest.md 1.2 KB
- rules/async-api-routes.md 1.1 KB
- rules/async-cheap-condition-before-await.md 1.2 KB
- rules/async-defer-await.md 2.1 KB
- rules/async-dependencies.md 978 B
- rules/async-parallel.md 682 B
- rules/async-suspense-boundaries.md 2.5 KB
- rules/bundle-analyzable-paths.md 2.3 KB
- rules/bundle-barrel-imports.md 2.4 KB
- rules/bundle-conditional.md 980 B
- rules/bundle-defer-third-party.md 969 B
- rules/bundle-dynamic-imports.md 826 B
- rules/bundle-preload.md 1.2 KB
- rules/client-event-listeners.md 2.0 KB
- rules/client-localstorage-schema.md 2.0 KB
- rules/client-passive-event-listeners.md 1.7 KB
- rules/client-swr-dedup.md 1.2 KB
- rules/js-batch-dom-css.md 1.6 KB
- rules/js-cache-function-results.md 2.0 KB
- rules/js-cache-property-access.md 560 B
- rules/js-cache-storage.md 1.7 KB
- rules/js-combine-iterations.md 785 B
- rules/js-early-exit.md 1.2 KB
- rules/js-flatmap-filter.md 1.4 KB
- rules/js-hoist-regexp.md 1.0 KB
- rules/js-index-maps.md 874 B
- rules/js-length-check-first.md 1.8 KB
- rules/js-min-max-loop.md 2.3 KB
- rules/js-request-idle-callback.md 2.6 KB
- rules/js-set-map-lookups.md 556 B
- rules/js-tosorted-immutable.md 1.8 KB
- rules/rendering-activity.md 590 B
- rules/rendering-animate-svg-wrapper.md 1.2 KB
- rules/rendering-conditional-render.md 1020 B
- rules/rendering-content-visibility.md 853 B
- rules/rendering-hoist-jsx.md 1.1 KB
- rules/rendering-hydration-no-flicker.md 2.3 KB
- rules/rendering-hydration-suppress-warning.md 872 B
- rules/rendering-resource-hints.md 2.5 KB
- rules/rendering-script-defer-async.md 1.8 KB
- rules/rendering-svg-precision.md 616 B
- rules/rendering-usetransition-loading.md 2.0 KB
- rules/rerender-defer-reads.md 1012 B
- rules/rerender-dependencies.md 869 B
- rules/rerender-derived-state-no-effect.md 1.2 KB
- rules/rerender-derived-state.md 757 B
- rules/rerender-functional-setstate.md 3.0 KB
- rules/rerender-lazy-state-init.md 2.0 KB
- rules/rerender-memo-with-default-value.md 1.1 KB
- rules/rerender-memo.md 1.2 KB
- rules/rerender-move-effect-to-event.md 1.2 KB
- rules/rerender-no-inline-components.md 2.1 KB
- rules/rerender-simple-expression-in-memo.md 1018 B
- rules/rerender-split-combined-hooks.md 1.8 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 First seen · 150 lines · 65 tokens per session scan A 74e45648634f
react-best-practices is a skill published in the GitHub repository georgekhananaev/claude-skills-vault (30 stars, last pushed 2mo ago), licensed MIT. It adds 65 tokens to every session and 1,762 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 97% identical to react-performance, differing in 5 lines, and is treated as a copy.
Other skills, from other repositories
design-loop
Autonomous multi-page site builder using a baton-passing loop. Each iteration reads a task from .design/next-prompt.md, generates a page in HTML/Tailwind, integrates it into the site, verifies visually, then writes the next task to keep the loop alive. Use whenever the user asks to build an entire site autonomously…
google-apps-script
Build Google Apps Script automation for Sheets and Workspace. Custom menus, triggers (onEdit / time-driven / form submit), dialogs, sidebars, email batches, PDF export, external API. Use whenever the user wants to automate a Google Sheet, build a Sheets menu / sidebar / dialog, hit a Sheets row from email or a…
cloudflare-api
Hit the Cloudflare REST API directly for operations that wrangler and MCP can't handle well. Bulk DNS, custom hostnames, email routing, cache purge, WAF rules, redirect rules, zone settings, Worker routes, D1 cross-database queries, R2 bulk operations, KV bulk read/write, Vectorize queries, Queues, and fleet-wide…
deep-research
Deep research and discovery before building something new. Explores local projects for reusable code, researches competitors, reads forums and reviews, analyses plugin ecosystems, investigates technical options, and produces a comprehensive research brief. Three depths: focused (30 min), wide (1-2 hours), deep (3-6…
elevenlabs-agents
Build conversational AI voice agents on the ElevenLabs platform. Configure agent + tools + knowledge base, integrate SDK (React / React Native / Swift / JS / server-side), test, deploy. Use whenever the user mentions ElevenLabs, building a voice agent, an AI phone system, an AI receptionist, conversational AI, or…
frontend
Builds, styles, and polishes anything drawn with HTML, CSS, or SVG: web UI, pages, components, HTML reports rendered to PDF or print, figures, PNG/SVG diagrams, slides, and images for Notion or Slack. Use for any styling, layout, animation, or visual-quality task, or when asked to make something look or feel a certain…