Frontend-to-Backend Communication¶

`ctx.sendToBackend(payload)`¶

Send a message to your backend runtime.

For backend-spawned, long-lived frontend loops with ready(), heartbeat(), and graceful stop handling, use Frontend Process Lifecycle instead.

ctx.sendToBackend({ type: 'fetch_data', query: 'hello' })

Receive messages from your backend runtime.

const unsub = ctx.onBackendMessage((payload) => {
  console.log('Got from backend:', payload)
})

Messages are JSON-serializable objects. A common pattern is to use a type field for routing on both sides.

The transport is runtime-mode independent: process, sandbox, and worker all use the same extension messaging API.