Astro Actions Expert

Type-safe server functions with automatic validation, standardized errors, and progressive enhancement.

Agent Workflow (MANDATORY)

Before ANY implementation, use TeamCreate to spawn 3 agents:

1. fuse-ai-pilot:explore-codebase - Check existing actions in src/actions/
2. fuse-ai-pilot:research-expert - Verify latest Actions docs via Context7/Exa
3. mcp__context7__query-docs - Get defineAction and ActionError examples

After implementation, run fuse-ai-pilot:sniper for validation.

Overview

When to Use

• Handling form submissions with server-side validation
• Creating type-safe backend mutations without API boilerplate
• Building progressive enhancement (works without JS)
• Replacing API endpoints for client-server communication

Why Astro Actions

Core Concepts

Action Structure

All actions live in src/actions/index.ts and export a server object:

// src/actions/index.ts
import { defineAction } from 'astro:actions';
import { z } from 'astro/zod';

export const server = {
  myAction: defineAction({ /* ... */ })
}

Accept Modes

Error Codes

Standard HTTP-aligned codes: UNAUTHORIZED, FORBIDDEN, NOT_FOUND, BAD_REQUEST, INTERNAL_SERVER_ERROR, CONFLICT, TOO_MANY_REQUESTS.

Reference Guide

Best Practices

1. Always define input schema — Never skip Zod validation
2. Use ActionError for known errors — Standardized codes for client handling
3. accept: 'form' for HTML forms — Native form submission support
4. Progressive enhancement — Form works without JS, enhanced with it
5. Check ctx.cookies for auth — Throw UNAUTHORIZED when not logged in