Shard VPN fabric session streams

agents/rap-node-agent/internal/config/config.go

@@ -30,6 +30,7 @@ type Config struct {
 	VPNFabricSessionTransportEnabled      bool
 	MeshQUICFabricEnabled                 bool
 	MeshQUICFabricListenAddr              string
+	VPNFabricSessionStreamShards          int
 	VPNFabricQUICMaxStreamsPerConn        int
 	VPNFabricQUICIdleTTL                  time.Duration
 	MeshProductionObservationSinkCapacity int
@@ -73,6 +74,7 @@ func Load(args []string, env map[string]string) (Config, error) {
 	fs.BoolVar(&cfg.VPNFabricSessionTransportEnabled, "vpn-fabric-session-transport-enabled", getEnvBool(env, "RAP_VPN_FABRIC_SESSION_TRANSPORT_ENABLED", false), "Route VPN packet transport over persistent fabric session when explicitly enabled. Disabled by default.")
 	fs.BoolVar(&cfg.MeshQUICFabricEnabled, "mesh-quic-fabric-enabled", getEnvBool(env, "RAP_MESH_QUIC_FABRIC_ENABLED", false), "Enable QUIC/UDP fabric listener. Disabled by default.")
 	fs.StringVar(&cfg.MeshQUICFabricListenAddr, "mesh-quic-fabric-listen-addr", getEnv(env, "RAP_MESH_QUIC_FABRIC_LISTEN_ADDR", ""), "Listen address for QUIC/UDP fabric endpoint, for example :19443.")
+	fs.IntVar(&cfg.VPNFabricSessionStreamShards, "vpn-fabric-session-stream-shards", getEnvInt(env, "RAP_VPN_FABRIC_SESSION_STREAM_SHARDS", 4), "VPN fabric-session stream shards per traffic class.")
 	fs.IntVar(&cfg.VPNFabricQUICMaxStreamsPerConn, "vpn-fabric-quic-max-streams-per-conn", getEnvInt(env, "RAP_VPN_FABRIC_QUIC_MAX_STREAMS_PER_CONN", 64), "Maximum logical fabric-session streams per cached VPN QUIC carrier connection.")
 	fs.DurationVar(&cfg.VPNFabricQUICIdleTTL, "vpn-fabric-quic-idle-ttl", time.Duration(getEnvInt(env, "RAP_VPN_FABRIC_QUIC_IDLE_TTL_SECONDS", 300))*time.Second, "Idle TTL for cached VPN QUIC carrier connections.")
 	fs.IntVar(&cfg.MeshProductionObservationSinkCapacity, "mesh-production-observation-sink-capacity", getEnvSignedInt(env, "RAP_MESH_PRODUCTION_OBSERVATION_SINK_CAPACITY", 0), "Bounded local metadata-only production envelope observation sink capacity. Disabled when 0.")
@@ -112,6 +114,12 @@ func Load(args []string, env map[string]string) (Config, error) {
 	cfg.MeshListenAddr = strings.TrimSpace(cfg.MeshListenAddr)
 	cfg.MeshQUICFabricListenAddr = strings.TrimSpace(cfg.MeshQUICFabricListenAddr)
 	cfg.MeshListenPortMode = strings.ToLower(strings.TrimSpace(cfg.MeshListenPortMode))
+	if cfg.VPNFabricSessionStreamShards <= 0 {
+		cfg.VPNFabricSessionStreamShards = 4
+	}
+	if cfg.VPNFabricSessionStreamShards > 64 {
+		cfg.VPNFabricSessionStreamShards = 64
+	}
 	if cfg.VPNFabricQUICMaxStreamsPerConn <= 0 {
 		cfg.VPNFabricQUICMaxStreamsPerConn = 64
 	}