isExternalHttpUrl treated any http(s):// URL as external, so an absolute link
back to the app's own host (e.g. https://self/p/{uuid}, /settings/members)
emitted by the assistant stayed clickable on the anonymous share, leaking
internal UUIDs/structure and pointing at auth-gated routes. Classify a link as
external only when its host differs from window.location.host; unparseable URLs
are treated as internal (fail-closed). Tests cover own-origin absolute (flag
on -> inert), external host (kept with safe rel/target), dangerous schemes, and
no behavior change for the internal chat (flag off).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>