The component exposed the internal HostBridge to hosts as-is, which
carried the host's requests as rxjs observables. That made rxjs part of
the public API of a package that bundles its own copy of it, so a host
would build bridges with a different rxjs than the one Element Call
consumed them with — and asked every host to learn rxjs to change the
theme.
A component host now implements plain async callbacks for what Element
Call tells it (`ElementCallHostBridge`, all optional), and makes its own
requests through an imperative handle on the component's `ref`
(`ElementCallHandle`: setTheme, join, hangUp, setDeviceMute), each
resolving once Element Call has acted and rejecting when nothing in
Element Call can. `component/host.ts` adapts that to the HostBridge the
rest of Element Call still speaks, with a bridge whose identity never
changes, so a host re-creating its callbacks on render restarts nothing.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
