Expose VPN fabric smoke fanout

agents/rap-node-agent/cmd/mesh-live-smoke/main.go

@@ -42,6 +42,7 @@ type smokeReport struct {
 	FabricSessionRoundTrips int            `json:"fabric_session_round_trips"`
 	FabricVPNPacketAccepted bool           `json:"fabric_vpn_packet_accepted"`
 	FabricVPNPacketSharded  bool           `json:"fabric_vpn_packet_sharded"`
+	FabricVPNPacketFanout   int            `json:"fabric_vpn_packet_fanout"`
 	FabricQUICAccepted      bool           `json:"fabric_quic_accepted"`
 	FabricQUICEndpoint      string         `json:"fabric_quic_endpoint"`
 	FabricSessionLatencyMS  int64          `json:"fabric_session_latency_ms"`
@@ -140,7 +141,7 @@ func run(ctx context.Context) (smokeReport, error) {
 		string(firstFabricSessionResponse.Payload) == "mesh-live-smoke-fabric-session" &&
 		secondFabricSessionResponse.Type == fabricproto.FramePong &&
 		string(secondFabricSessionResponse.Payload) == "mesh-live-smoke-fabric-session-2"
-	fabricVPNPacketAccepted, fabricVPNPacketSharded, err := smokeFabricVPNPacketOverSession(ctx, fabricSession)
+	fabricVPNPacketAccepted, fabricVPNPacketSharded, fabricVPNPacketFanout, err := smokeFabricVPNPacketOverSession(ctx, fabricSession)
 	if err != nil {
 		return smokeReport{}, fmt.Errorf("fabric vpn packet session smoke: %w", err)
 	}
@@ -163,6 +164,7 @@ func run(ctx context.Context) (smokeReport, error) {
 		FabricSessionRoundTrips: 2,
 		FabricVPNPacketAccepted: fabricVPNPacketAccepted,
 		FabricVPNPacketSharded:  fabricVPNPacketSharded,
+		FabricVPNPacketFanout:   fabricVPNPacketFanout,
 		FabricQUICAccepted:      fabricQUICAccepted,
 		FabricQUICEndpoint:      fabricQUICEndpoint,
 		FabricSessionLatencyMS:  fabricSessionLatency.Milliseconds(),
@@ -243,7 +245,7 @@ func smokeQUICTLSConfig() *tls.Config {
 	}
 }
 
-func smokeFabricVPNPacketOverSession(ctx context.Context, fabricSession *mesh.FabricSessionClient) (bool, bool, error) {
+func smokeFabricVPNPacketOverSession(ctx context.Context, fabricSession *mesh.FabricSessionClient) (bool, bool, int, error) {
 	const interactiveStreamID uint64 = 4400
 	const bulkStreamID uint64 = 4401
 	pump := fabricSession.StartPump(ctx, mesh.FabricSessionPumpOptions{
@@ -257,7 +259,7 @@ func smokeFabricVPNPacketOverSession(ctx context.Context, fabricSession *mesh.Fa
 		{Type: fabricproto.FrameOpenStream, StreamID: bulkStreamID, TrafficClass: fabricproto.TrafficClassBulk},
 	} {
 		if err := pump.Send(ctx, frame); err != nil {
-			return false, false, err
+			return false, false, 0, err
 		}
 	}
 	transport := &vpnruntime.FabricSessionPacketTransport{
@@ -273,7 +275,7 @@ func smokeFabricVPNPacketOverSession(ctx context.Context, fabricSession *mesh.Fa
 	bulkPacket := smokeIPv4TCPPacket([4]byte{10, 77, 0, 2}, [4]byte{192, 168, 200, 95}, 51000, 443, 0)
 	controlPacket := smokeIPv4TCPPacket([4]byte{10, 77, 0, 2}, [4]byte{192, 168, 200, 95}, 51001, 3389, 0x02)
 	if err := transport.SendGatewayPacketBatch(ctx, [][]byte{bulkPacket, controlPacket}); err != nil {
-		return false, false, err
+		return false, false, 0, err
 	}
 	timer := time.NewTimer(3 * time.Second)
 	defer timer.Stop()
@@ -291,15 +293,16 @@ func smokeFabricVPNPacketOverSession(ctx context.Context, fabricSession *mesh.Fa
 						snapshot["sharding_active"] == true &&
 						snapshot["send_class_count"] == 2 &&
 						snapshot["send_stream_count"] == 2
-					return true, sharded, nil
+					fanout, _ := snapshot["last_batch_frame_count"].(uint64)
+					return true, sharded, int(fanout), nil
 				}
 			}
 		case err := <-pump.Errors():
-			return false, false, err
+			return false, false, 0, err
 		case <-timer.C:
-			return false, false, fmt.Errorf("timed out waiting for fabric vpn packet ack")
+			return false, false, 0, fmt.Errorf("timed out waiting for fabric vpn packet ack")
 		case <-ctx.Done():
-			return false, false, ctx.Err()
+			return false, false, 0, ctx.Err()
 		}
 	}
 }

docs/architecture/DISTRIBUTED_FABRIC_NODE_PROTOCOL_PLAN.md

@@ -404,6 +404,8 @@ before they are framed, so one gateway batch containing many browser flows does
 not collapse onto the first packet's logical stream.
 `mesh-live-smoke` now sends mixed bulk and interactive VPN packets in a single
 fabric-session batch and requires them to remain sharded.
+The smoke report also exposes the mixed-batch frame fanout so regressions show
+up as a concrete fanout drop, not just a failed boolean.
 Fabric-session packet transport snapshots now report packets per stream plus
 last/max batch fanout, making real multi-site load distribution measurable from
 gateway status.