T2.2: BandwidthEstimator with cwnd/REMB target_send_bps

crates/wzp-transport/src/quic.rs

@@ -26,7 +26,7 @@ pub struct QuinnPathSnapshot {
     /// Total congestion events observed by the QUIC stack.
     pub congestion_events: u64,
     /// Current congestion window in bytes.
-    pub cwnd: u64,
+    pub cwnd_bytes: u64,
     /// Total packets sent on this path.
     pub sent_packets: u64,
     /// Total packets lost on this path.
@@ -34,6 +34,8 @@ pub struct QuinnPathSnapshot {
     /// Current PMTUD-discovered maximum datagram payload size (bytes).
     /// Starts at `initial_mtu` (1200) and grows as PMTUD probes succeed.
     pub current_mtu: usize,
+    /// Bytes currently in flight (unacknowledged).
+    pub bytes_in_flight: u64,
 }
 
 /// QUIC-based transport implementing the `MediaTransport` trait.
@@ -107,10 +109,13 @@ impl QuinnTransport {
             rtt_ms,
             loss_pct,
             congestion_events: stats.path.congestion_events,
-            cwnd: stats.path.cwnd,
+            cwnd_bytes: stats.path.cwnd,
             sent_packets: stats.path.sent_packets,
             lost_packets: stats.path.lost_packets,
             current_mtu,
+            // quinn 0.11 does not expose bytes_in_flight on PathStats;
+            // reserved for when the underlying stat becomes available.
+            bytes_in_flight: 0,
         }
     }