Draft: rfc9002

Commentary: Addresses comments 2 , 4 , 7 , 8 , 9 , and 11 . 
 one tiny suggestion , but lgtm -- thanks for doing this !
Paragraph (version A):
QUIC uses a probe timeout (PTO; see pto), with a timer based on TCP's
RTO computation; see RFC6297.  QUIC's PTO includes the peer's maximum
expected acknowledgment delay instead of using a fixed minimum
timeout.
Paragraph (version B):
QUIC uses a probe timeout (PTO; see pto), with a timer based on TCP's
retransmission timeout (RTO) computation; see RFC6298.  QUIC's PTO
includes the peer's maximum expected acknowledgment delay instead of
using a fixed minimum timeout.
Paragraph (version A):
Spuriously declaring packets as lost leads to unnecessary
retransmissions and may result in degraded performance due to the
actions of the congestion controller upon detecting loss.
Implementations can detect spurious retransmissions and increase the
reordering threshold in packets or time to reduce future spurious
retransmissions and loss events.  Implementations with adaptive time
thresholds MAY choose to start with smaller initial reordering
thresholds to minimize recovery latency.
Paragraph (version B):
Spuriously declaring packets as lost leads to unnecessary
retransmissions and may result in degraded performance due to the
actions of the congestion controller upon detecting loss.
Implementations can detect spurious retransmissions and increase the
packet or time reordering threshold to reduce future spurious
retransmissions and loss events.  Implementations with adaptive time
thresholds MAY choose to start with smaller initial reordering
thresholds to minimize recovery latency.
Paragraph (version A):
Initial packets and Handshake packets could be never acknowledged,
but they are removed from bytes in flight when the Initial and
Handshake keys are discarded, as described below in discarding-
packets.  When Initial or Handshake keys are discarded, the PTO and
loss detection timers MUST be reset, because discarding keys
indicates forward progress and the loss detection timer might have
been set for a now discarded packet number space.
Paragraph (version B):
When the Initial keys and Handshake keys are discarded (discarding-
packets), any Initial packets and Handshake packets can no longer be
acknowledged, so they are removed from bytes in flight.  When Initial
or Handshake keys are discarded, the PTO and loss detection timers
MUST be reset, because discarding keys indicates forward progress and
the loss detection timer might have been set for a now discarded
packet number space.
Paragraph (version A):
Since the server could be blocked until more datagrams are received
from the client, it is the client's responsibility to send packets to
unblock the server until it is certain that the server has finished
its address validation (see Section 8 of QUIC-TRANSPORT).  That is,
the client MUST set the probe timer if the client has not received an
acknowledgment for any of its Handshake packets and the handshake is
not confirmed (see Section 4.1.2 of QUIC-TLS), even if there are no
packets in flight.  When the PTO fires, the client MUST send a
Handshake packet if it has Handshake keys, otherwise it MUST send an
Initial packet in a UDP datagram with a payload of at least 1200
bytes.
Paragraph (version B):
Since the server could be blocked until more datagrams are received
from the client, it is the client's responsibility to send packets to
unblock the server until it is certain that the server has finished
its address validation (see Section 8 of QUIC-TRANSPORT).  That is,
the client MUST set the PTO timer if the client has not received an
acknowledgment for any of its Handshake packets and the handshake is
not confirmed (see Section 4.1.2 of QUIC-TLS), even if there are no
packets in flight.  When the PTO fires, the client MUST send a
Handshake packet if it has Handshake keys, otherwise it MUST send an
Initial packet in a UDP datagram with a payload of at least 1200
bytes.
Paragraph (version A):
It is expected that keys are discarded after packets encrypted with
them would be acknowledged or declared lost.  However, Initial and
Handshake secrets are discarded as soon as handshake and 1-RTT keys
are proven to be available to both client and server; see
Section 4.9.1 of QUIC-TLS.
Paragraph (version B):
It is expected that keys are discarded at some time after the packets
encrypted with them are either acknowledged or declared lost.
However, Initial and Handshake secrets are discarded as soon as
handshake and 1-RTT keys are proven to be available to both client
and server; see Section 4.9.1 of QUIC-TLS.
Paragraph (version A):
When bytes in flight is smaller than the congestion window and
sending is not pacing limited, the congestion window is under-
utilized.  When this occurs, the congestion window SHOULD NOT be
increased in either slow start or congestion avoidance.  This can
happen due to insufficient application data or flow control limits.
Paragraph (version B):
When bytes in flight is smaller than the congestion window and
sending is not pacing limited, the congestion window is under-
utilized.  This can happen due to insufficient application data or
flow control limits.  When this occurs, the congestion window SHOULD
NOT be increased in either slow start or congestion avoidance.