Next.js: Server Actions и мутации — ментальная модель

Question

Accepted Answer

Server Action — `async` + `'use server'`, runs only server, callable from client; Next compiles в **public POST endpoint** с stable ID. Mutation half of RSC: forms без JS, без hand-written API route.

## Разбор

Server Components solved *reading*. Server Actions solve *writing*. Вместо `fetch('/api/todos', { method: 'POST' })` — function + `'use server'` + call; Next wires transport.

Mental model for safety: **не «trusted server call», а public HTTP endpoint с funny name.** Anyone POST generated ID с any payload. **Authenticate и validate как raw route handler.**

Bound to `<form>` → **progressive enhancement**: submit и mutate до/без JS hydration.

## Итог

Ergonomic sugar не убирает network boundary — auth, validate, revalidate обязательны на каждой action.