flowControlSnapshot dump from sweep_frames_200 against nostrnests.com proved
the speaker side was perfectly healthy (~5 EB conn-credit unused, 10 000-stream
peer cap unused, 0 bytes stuck in send buffers, all 200 streams opened) yet
the listener cliffed at frame 99. The constraint was on the listener's
receive side: our :quic was advertising initial_max_streams_uni = 100 at
handshake and never extending it, so the relay could only open 100 uni
streams to us *for the lifetime of the connection*. Each Opus frame the
relay forwards is a fresh peer-initiated uni stream, so any broadcast
longer than ~100 frames silently truncated at the audience.
QuicConnection:
- peerInitiatedUniCount / peerInitiatedBidiCount counters (incremented
in getOrCreatePeerStreamLocked).
- advertisedMaxStreamsUni / advertisedMaxStreamsBidi tracking, starting
at config.initialMaxStreams* and raised by the writer.
QuicConnectionWriter.appendFlowControlUpdates:
- When peerInitiatedUniCount + cfg.initialMaxStreamsUni / 2 >=
advertisedMaxStreamsUni, emit MaxStreamsFrame(bidi=false, newCap)
where newCap = peerInitiatedUniCount + cfg.initialMaxStreamsUni.
Same pattern the existing MaxDataFrame / MaxStreamDataFrame
extension uses; same half-window threshold so we don't spam the
peer.
- Symmetric branch for bidi.
PeerStreamCreditExtensionTest:
- Writer DOES emit MAX_STREAMS_UNI when peer's lifetime uni-stream count
crosses the half-window threshold; advertisedMaxStreamsUni updates.
- Writer DOES NOT emit MAX_STREAMS_UNI below the threshold;
advertisedMaxStreamsUni stays at the initial cap.
Updated nestsClient/plans/2026-05-01-quic-stream-cliff-investigation.md
with the fc-snapshot dump that proved the cause and the fix that
addresses it. The framesPerGroup=5 mitigation in NestMoqLiteBroadcaster
can be reverted to 1 once the prod sweep confirms the cliff is gone.
All :quic and :nestsClient JVM tests pass.
Claude
d391ae1db9