cache-components

Files (4)

• PATTERNS.md
• REFERENCE.md
• SKILL.md
• TROUBLESHOOTING.md

SKILL.md (first lines)

# Next.js Cache Components

> **Auto-activation**: This skill activates automatically in projects with `cacheComponents: true` in next.config.

## Project Detection

When starting work in a Next.js project, check if Cache Components are enabled:

```bash
# Check next.config.ts or next.config.js for cacheComponents
grep -r "cacheComponents" next.config.* 2>/dev/null
```

If `cacheComponents: true` is found, apply this skill's patterns proactively when:

- Writing React Server Components
- Implementing data fetching
- Creating Server Actions with mutations
- Optimizing page performance
- Reviewing existing component code

Cache Components enable **Partial Prerendering (PPR)** - mixing static HTML shells with dynamic streaming content for optimal performance.

## Philosophy: Code Over Configuration

Cache Components represents a shift from **segment configuration** to **compositional code**:

| Before (Deprecated)                     | After (Cache Components)                  |
| --------------------------------------- | ----------------------------------------- |
| `export const revalidate = 3600`        | `cacheLife('hours')` inside `'use cache'` |
| `export const dynamic = 'force-static'` | Use `'use cache'` and Suspense boundaries |
| All-or-nothing static/dynamic           | Granular: static shell + cached + dynamic |

**Key Principle**: Components co-locate their caching, not just their data. Next.js provides build-time feedback to guide you toward optimal patterns.

## Core Concept

```
┌─────────────────────────────────────────────────────┐
│                   Static Shell                       │
│  (Sent immediately to browser)                       │
│                                                      │
│  ┌─────────────┐  ┌─────────────┐  ┌─────────────┐  │
│  │   Header    │  │  Cached     │  │  Suspense   │  │
│  │  (static)   │  │  Content    │  │  Fallback   │  │
│  └─────────────┘  └─────────────┘  └──────┬──────┘  │
│                                           │         │
│                                    ┌──────▼──────┐  │
│                                    │  Dynamic    │  │
│                                    │  (streams)  │  │
│                                    └─────────────┘  │
└─────────────────────────────────────────────────────┘
```

## Mental Model: The Caching Decision Tree

When writing a React Server Component, ask these questions in order:

```
┌─────────────────────────────────────────────────────────┐
│ Does this component fetch data or perform I/O?          │
└─────────────────────┬───────────────────────────────────┘
                      │
           ┌──────────▼──────────┐
           │   YES               │ NO → Pure component, no action needed
           └──────────┬──────────┘
                      │
    ┌─────────────────▼─────────────────┐
    │ Does it depend on request context? │
    │ (cookies, headers, searchParams)   │
    └─────────────────┬─────────────────┘
                      │
         ┌────────────┴────────────┐
         │                         │
    ┌────▼────┐              ┌─────▼─────┐
    │   YES   │              │    NO     │
    └────┬────┘              └─────┬─────┘
         │                         │
         │                   ┌─────▼─────────────────┐
         │                   │ Can this be cached?   │
         │                   │ (same for all users?) │
         │                   └─────┬─────────────────┘
         │                         │
         │              ┌──────────┴──────────┐
         │              │                     │
         │         ┌────▼────┐          ┌─────▼─────┐
         │         │   YES   │          │    NO     │
         │         └────┬────┘          └─────┬─────┘
         │              │                     │
         │              ▼                     │
         │         'use cache'                │
         │         + cacheTag()               │
         │         + cacheLife()              │
         │                                    │
         └──────────────┬─────────────────────┘
                        │
                        ▼
              Wrap in <Suspense>
              (dynamic streaming)
```

**Key insight**: The `'use cache'` directive is for data that's the _same across users_. User-specific data stays dynamic with Suspense.

## Quick Start

### Enable Cache Components

```typescript
// next.config.ts
import type { NextConfig } from 'next'

const nextConfig: NextConfig = {
  cacheComponents: true,
}

export default nextConfig
```

### Basic Usage

From evgeshniyzik-dev/nextjs, MIT.

More from evgeshniyzik-dev/nextjs