When a listener joins a Nest before the speaker starts publishing,
moq-rs FINs the SUBSCRIBE bidi immediately without sending
SubscribeOk or SubscribeDrop. MoqLiteSession.subscribe surfaces that
as a MoqLiteSubscribeException("subscribe stream FIN before reply"),
which the listener wrapper translated to MoqProtocolException via
MoqLiteNestsListener.wrapSubscription.
The reconnecting wrapper's inner re-issue loop then did:
val handle = try { opener(listener) } catch (...) { null } ?: break
— breaking out of the loop forever. The outer collectLatest only
re-runs on listener swap (session reconnect), so once the first
SUBSCRIBE failed the audio path stayed dead until the user manually
disconnected and reconnected. With the typical join-order being
"listener taps Join before speaker taps Start", this hit nearly
every nest.
The kdoc on pumpAnnounceWatch claims "moq-lite supports subscribe-
before-announce, so a subscribe issued during the gap … attaches
cleanly when the new publisher comes up" — true for some publisher-
cycle gaps mid-broadcast, but verifiably false for the cold-start
case where the publisher hasn't existed yet on the relay's view of
the namespace. Production trace (commit 283e776):
14:23:29.556 subscribe id=0 track='audio/data': SUBSCRIBE bytes flushed
14:23:29.597 subscribe id=0: bidi closed BEFORE any response parsed
14:23:29.617 ReconnectingHandle.opener threw MoqProtocolException — pump breaks
14:23:33.604 announce update status=Active suffix=… (4 s later)
14:23:34.218 publish suffix=… (speaker starts publishing)
Fix: instead of `break`, treat opener-throw as a transient failure
and retry after SUBSCRIBE_RETRY_BACKOFF_MS (1 s). The outer
collectLatest still cancels the inner loop on listener swap, and
unsubscribeAction.cancel() still tears the pump down on consumer
release, so the retry loop is bounded by both the session and the
caller. 1 s is well over moq-rs's typical announce-propagation
window (< 200 ms in traces) and short enough that the listener
attaches within a second of the speaker actually publishing.
https://claude.ai/code/session_01PYYez8a6sjiakyjAxsfCEQ
Claude
9f542a6ff4