Webview API

Inside a webview document, Drawdy injects a global acquireDrawdyApi(). Acquire it once; messages you post reach the owning driver as subscription:webview:message events.

type DrawdyWebviewApi = {
    postMessage(message: unknown, transfer?: Transferable[]): void;
    onMessage(listener: (message: unknown) => void): () => void;
};

postMessage sends a driver-defined message. It is buffered until the host connects, so it is safe to call immediately. Large payloads (ArrayBuffer, ImageBitmap, …) referenced inside message can be listed in transfer to move rather than copy them; they are re-transferred at every relay hop.
onMessage listens for messages the driver sends via command:webview:post-message. It returns a dispose function.

Guide

Protocol reference

Webview API