developer guide

Runtime API

How extensions execute inside Rext.

The sandbox

Extensions run in an isolated runtime with no direct filesystem or device access. All I/O goes through capability-checked APIs: network requests are restricted to hosts declared in the manifest, and storage is scoped per extension.

Handling requests

Rext invokes your extension with typed requests — a search query, a metadata lookup, a playback resolution — and expects typed responses. Long-running work should report progress so the UI stays responsive.

Errors

Throw structured errors with a user-presentable message. Rext surfaces them inline and never crashes the host app because of an extension failure.