Replace the synchronous non-cancellable _stream.ReadByte() for the kind byte in FrameReader.ReadFrameAsync with an async ReadExactAsync(new byte[1], ct) call so the full frame read honours the EffectiveCallTimeout-linked token and cannot wedge the call gate when the sidecar stalls mid-frame. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>