# react-selective-hydration

Guides your coding agent in setting up selective hydration and streaming SSR in React 18+. It makes interactive parts responsive before the entire JavaScript bundle downloads.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 943 installs · ★ 257
- Author: patterns.dev
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/PatternsDev/skills/tree/HEAD/react/react-selective-hydration/SKILL.md
- Updated: 2026-04-15
- HTML: https://affpapa.org/en/nevibecode/skills/react-selective-hydration

## What it does

Standard React SSR with `renderToString` halts tree transmission until every server component resolves. The client then stays inert until all JavaScript downloads. This skill directs the agent to replace synchronous rendering with React 18 streaming architecture.

Under the hood, the skill provides specific rules for server renderers: `renderToPipeableStream` for Node and `renderToReadableStream` for Web Stream edge runtimes. It specifies placing data-heavy blocks inside `Suspense` boundaries so initial HTML streams without delay. Interactive sibling components hydrate right away.

The pattern requires React 18+ with `hydrateRoot`. Putting critical interactive components inside long-lived loading fallbacks breaks the user experience, defeating the purpose of selective hydration.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add PatternsDev/skills --skill react-selective-hydration -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/react-selective-hydration/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/react-selective-hydration/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add PatternsDev/skills --skill react-selective-hydration -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/react-selective-hydration/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add PatternsDev/skills --skill react-selective-hydration -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/react-selective-hydration/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install PatternsDev/skills react-selective-hydration
```

2. **Manually: put the files in place**
- File: `.github/skills/react-selective-hydration/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add PatternsDev/skills --skill react-selective-hydration -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/PatternsDev/skills --path react/react-selective-hydration
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/react-selective-hydration/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add PatternsDev/skills --skill react-selective-hydration -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/PatternsDev/skills/tree/HEAD/react/react-selective-hydration/SKILL.md

## When to use it
- migrate from `renderToString` to streaming SSR with `renderToPipeableStream` or `renderToReadableStream`
- isolate slow data-fetching components behind `Suspense` boundaries
- hydrate critical interactive components before all page scripts finish downloading
- configure `hydrateRoot` for phased client-side hydration in React 18+

## Example prompts
- Migrate our SSR setup from `renderToString` to `renderToPipeableStream` with selective hydration
- Wrap the comments widget in `Suspense` so slow API requests do not block hydration elsewhere
- Check `entry.server.tsx` and implement streaming SSR for our Node runtime

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 2df2ab1aa20375b8.

BEGIN THIRD-PARTY FILE 2df2ab1aa20375b8
```text
---
name: react-selective-hydration
description: Teaches selective hydration combined with streaming SSR in React 18+. Use when you need to prioritize hydrating interactive components while streaming the rest of the page.
paths:
  - "**/*.tsx"
  - "**/*.jsx"
license: MIT
metadata:
  author: patterns.dev
  version: "1.1"
related_skills:
  - "hooks-pattern"
  - "hoc-pattern"
---

# Selective Hydration

In previous articles, we covered how SSR with hydration can improve user experience. React is able to (quickly) generate a tree on the server using the `renderToString` method that the `react-dom/server` library provides, which gets sent to the client after the entire tree has been generated. The rendered HTML is non interactive, until the JavaScript bundle has been fetched and loaded, after which React walks down the tree to hydrate and attaches the handlers.

However, this approach can lead to some performance issues due to some limitations with the current implementation.

## When to Use

- Use this when you want to make parts of your SSR page interactive before all JavaScript has loaded
- This is helpful when slow components (e.g., data-fetching components) are blocking the entire page's hydration

## Instructions

- Use `Suspense` boundaries to delineate independently hydratable chunks of UI
- Use `renderToPipeableStream` (Node) or `renderToReadableStream` (edge) for streaming SSR
- Place heavy data-fetching components inside `Suspense` so they don't delay sibling hydration
- Ensure critical interactive components are not inside long-lived loading fallbacks
- Use `hydrateRoot` (React 18+) to benefit from selective hydration

## Details

Before the server-rendered HTML tree is able to get sent to the client, all components need to be ready. This means that components that may rely on an external API call or any process that could cause some delays, might end up blocking smaller components from being rendered quickly.

Besides a slower tree generation, another issue is the fact that React only hydrates the tree once. This means that before React is able to hydrate any of the components, it needs to have fetched the JavaScript for all of the components before it's able to hydrate any of them. This means that smaller components (with smaller bundles) have to wait for the larger components's code to be fetched and loaded, until React is able to hydrate anything on your website. During this time, the website remained non-interactive.

React 18 solves these problems by allowing us to combine streaming server-side rendering with a new approach to hydration: Selective Hydration!
```
END THIRD-PARTY FILE 2df2ab1aa20375b8

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