On rooms with the `trusted` access level, any authenticated user
connected to the meeting can now manage the lobby. Requested by
several organizations, and a step toward generalized lobby
management once hubs and groups land (same organization only).
Being authenticated is not enough to grant the capability: a
`trusted` room means "trusted to join", not "trusted to decide who
else joins from outside the call". The new `CanManageLobby`
permission therefore also requires the requester to be currently
connected to the meeting, verified against LiveKit and failing
closed, like `IsPresentInMeeting`. The access level itself is never
cached and always read fresh, so an owner switching the room back to
`restricted` revokes the capability on the very next request - the
one guarantee we did not want to trade for performance.
Performance is traded elsewhere: the waiting list is polled by every
lobby manager, and on a trusted room that audience grows from a few
admins to potentially the whole meeting. Hitting LiveKit once per
poll per participant would not survive that fan-out, so presence is
memoized in Redis (`PresenceCache`, `PRESENCE_CACHE_TIMEOUT`, 1h).
Entries are created lazily because only the minority of participants
who actually manage a lobby ever need one, and only positive answers
are cached because a sticky negative would lock out someone joining
right after a miss for the whole TTL. Eager invalidation on
`participant_left`, `room_finished` and admin kick keeps the cache
honest; the TTL is the safety net when an event is lost, and its
value bounds how long a departed participant could still act.
Trade-offs in this v0:
* `PRESENCE_CLEAR_ON_PARTICIPANT_LEFT` gates the eager invalidation
on `participant_left`: its cost is one Redis DELETE per departure,
for every departure, so we want to be able to measure it in
production and turn it off independently of the feature. When
disabled, invalidation relies on `room_finished` and the TTL only,
widening the stale window above.
* This can put non-trivial pressure on the cache at scale; the
rollout will need to be monitored closely.
* The `participant_left` webhook must be enabled in the LiveKit
deployment, otherwise eager invalidation silently degrades to the
TTL-only behavior.
Ensure the participant requesting a mute action is still present
in the room before processing the request.
This mitigates scenarios where a previously issued token could be
reused after the meeting has ended.
Current token lifetime is intentionally long-lived and will be
refactored in the future to better align with LiveKit session
constraints. In the meantime, add this extra validation step to
reduce the attack surface.
Avoid mapping all Twirp errors to generic 500 responses.
Explicitly handle the case where a participant is no longer in
the room, as this may indicate suspicious behavior or a client
state issue.
Improve error discrimination to provide more accurate responses.
Refactor client-side LiveKit API calls to server-side endpoints
following LiveKit documentation recommendations for participant
management operations.
Replaces hacky direct client calls with proper backend-mediated
requests, improving security and following official LiveKit
lebaudantoine