▸ Agent Skills
2 min read

Version: 2.0.0

Get a SpacetimeDB Astro app running in under 5 minutes.

Prerequisites

Install the SpacetimeDB CLI tool

Create your project

Run the spacetime dev command to create a new project with a SpacetimeDB module and Astro client.

This will start the local SpacetimeDB server, publish your module, generate TypeScript bindings, and start the Astro development server.

spacetime dev --template astro-ts

Open your app

Navigate to http://localhost:4321 to see your app running.

The Astro app reads SPACETIMEDB_* variables on the server and PUBLIC_SPACETIMEDB_* variables in the client, so .env.local can configure both sides of the app.

Explore the project structure

Your project contains both server and client code using Astro SSR and a live React island for real-time updates.

Edit spacetimedb/src/index.ts to add tables and reducers. Edit src/pages/index.astro and src/components/PersonList.tsx to build your UI.

my-astro-app/
├── spacetimedb/              # Your SpacetimeDB module
│   └── src/
│       └── index.ts          # SpacetimeDB module logic
├── src/
│   ├── components/
│   │   ├── PersonList.tsx
│   │   ├── SpacetimeApp.tsx
│   │   └── DeferredPeopleSnapshot.astro
│   ├── lib/
│   │   └── spacetimedb-server.ts
│   ├── module_bindings/      # Auto-generated types
│   ├── layouts/
│   │   └── Layout.astro
│   ├── pages/
│   │   └── index.astro
│   └── styles/
│       └── global.css
└── package.json

Understand tables and reducers

Open spacetimedb/src/index.ts to see the module code. The template includes a person table and two reducers: add to insert a person, and sayHello to greet everyone.

Tables store your data. Reducers are functions that modify data and are the only way to write to the database.

import { schema, table, t } from 'spacetimedb/server';

const spacetimedb = schema({
  person: table(
    { public: true },
    {
      name: t.string(),
    }
  ),
});
export default spacetimedb;

export const add = spacetimedb.reducer(
  { name: t.string() },
  (ctx, { name }) => {
    ctx.db.person.insert({ name });
  }
);

export const sayHello = spacetimedb.reducer(ctx => {
  for (const person of ctx.db.person.iter()) {
    console.info(`Hello, ${person.name}!`);
  }
  console.info('Hello, World!');
});

Test with the CLI

Open a new terminal and navigate to your project directory. Then use the SpacetimeDB CLI to call reducers and query your data directly.

cd my-spacetime-app

# Call the add reducer to insert a person
spacetime call add Alice

# Query the person table
spacetime sql "SELECT * FROM person"
 name
---------
 "Alice"

# Call sayHello to greet everyone
spacetime call say_hello

# View the module logs
spacetime logs
2025-01-13T12:00:00.000000Z  INFO: Hello, Alice!
2025-01-13T12:00:00.000000Z  INFO: Hello, World!

Understand Astro SSR and real-time hydration

The SpacetimeDB SDK works both server-side and client-side. The template uses a hybrid approach:

  • Astro page (src/pages/index.astro): Fetches initial data on the server for a fast first render
  • React island (src/components/SpacetimeApp.tsx): Hydrates on the client and provides the SpacetimeDB connection
  • Live table UI (src/components/PersonList.tsx): Uses useTable() and useReducer() for real-time updates
---
import Layout from '../layouts/Layout.astro';
import SpacetimeApp from '../components/SpacetimeApp';
import { fetchPeople } from '../lib/spacetimedb-server';

const initialPeople = await fetchPeople();
---

<Layout title="astro-ts">
  <h1>astro-ts</h1>
  <SpacetimeApp client:load initialPeople={initialPeople} />
</Layout>

Understand Astro server islands

The template also includes a deferred Astro-only section to demonstrate server:defer.

src/components/DeferredPeopleSnapshot.astro fetches its own server-rendered snapshot, and src/pages/index.astro renders it as a server island without changing the main real-time client flow.

<DeferredPeopleSnapshot server:defer>
  <div slot="fallback">Loading deferred people snapshot…</div>
</DeferredPeopleSnapshot>

Last updated Oct 08, 2026