originHeader

sent as this request's Origin header when non-null, for a backend that allow-lists origins as a lightweight check on a public, keyless chat endpoint. Native engines (OkHttp/Darwin/CIO) send whatever is set here; a real browser (wasmJs) refuses to let a script override Origin — it's a forbidden header per the Fetch spec — so this is a no-op there and the browser's own Origin goes out instead.