An absent impl is invisible in the source, and this one keeps being
proposed. Closing on each clone's drop would end a live session the
moment a losing race future is dropped; closing on the last clone is
circular, since the cache entry is itself a clone and is removed by the
state handler a close fires. Ownership is carried by `OffererGuard` and
`Stream::WebRTC` instead, so say so where someone adding another holder
will look.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019UzcMTdYTEv2QbMHcTSUy3