Smoke test VPN route recovery

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

@@ -48,6 +48,8 @@ type smokeReport struct {
 	FabricVPNInteractive    int            `json:"fabric_vpn_interactive_or_control_channels"`
 	FabricVPNBulkWindow     int            `json:"fabric_vpn_bulk_parallel_window"`
 	FabricVPNInteractiveWin int            `json:"fabric_vpn_interactive_parallel_window"`
+	FabricVPNRouteRecovered bool           `json:"fabric_vpn_route_recovered"`
+	FabricVPNRouteSwitches  uint64         `json:"fabric_vpn_route_switch_count"`
 	FabricQUICAccepted      bool           `json:"fabric_quic_accepted"`
 	FabricQUICEndpoint      string         `json:"fabric_quic_endpoint"`
 	FabricQUICPressure      int            `json:"fabric_quic_capacity_pressure_percent"`
@@ -152,6 +154,7 @@ func run(ctx context.Context) (smokeReport, error) {
 		return smokeReport{}, fmt.Errorf("fabric vpn packet session smoke: %w", err)
 	}
 	fabricVPNBulkPressure, fabricVPNBulkChannels, fabricVPNInteractiveChannels, fabricVPNBulkWindow, fabricVPNInteractiveWindow := smokeVPNFlowSchedulerBulkPressure()
+	fabricVPNRouteRecovered, fabricVPNRouteSwitches := smokeVPNFlowSchedulerRouteRecovery()
 	fabricQUICAccepted, fabricQUICEndpoint, fabricQUICPressure, err := smokeQUICFabricSession(ctx)
 	if err != nil {
 		return smokeReport{}, fmt.Errorf("fabric quic smoke: %w", err)
@@ -177,6 +180,8 @@ func run(ctx context.Context) (smokeReport, error) {
 		FabricVPNInteractive:    fabricVPNInteractiveChannels,
 		FabricVPNBulkWindow:     fabricVPNBulkWindow,
 		FabricVPNInteractiveWin: fabricVPNInteractiveWindow,
+		FabricVPNRouteRecovered: fabricVPNRouteRecovered,
+		FabricVPNRouteSwitches:  fabricVPNRouteSwitches,
 		FabricQUICAccepted:      fabricQUICAccepted,
 		FabricQUICEndpoint:      fabricQUICEndpoint,
 		FabricQUICPressure:      fabricQUICPressure,
@@ -214,6 +219,19 @@ func smokeVPNFlowSchedulerBulkPressure() (bool, int, int, int, int) {
 		snapshot.RecommendedParallelWindows[vpnruntime.FabricTrafficClassInteractive]
 }
 
+func smokeVPNFlowSchedulerRouteRecovery() (bool, uint64) {
+	scheduler := vpnruntime.NewFabricFlowScheduler(8, 16)
+	channelID := "vpn-smoke-flow-0"
+	scheduler.RecordRouteFailure(channelID, "route-primary", "node-primary", fmt.Errorf("smoke primary unavailable"), time.Millisecond)
+	scheduler.RecordRouteSuccess(channelID, "route-alternate", "node-alternate", time.Millisecond)
+	snapshot := scheduler.Snapshot()
+	stat := snapshot.ChannelStats[channelID]
+	return stat.LastRecoveredFromRouteID == "route-primary" &&
+			stat.LastRouteID == "route-alternate" &&
+			snapshot.RouteRecoveredChannelCount == 1,
+		snapshot.RouteSwitchCount
+}
+
 func smokeQUICFabricSession(ctx context.Context) (bool, string, int, error) {
 	server, err := mesh.StartQUICFabricServer(ctx, mesh.QUICFabricServerConfig{
 		ListenAddr: "127.0.0.1:0",

docs/architecture/DISTRIBUTED_FABRIC_NODE_PROTOCOL_PLAN.md

@@ -443,6 +443,8 @@ pressure activation plus bulk/interactive window recommendations.
 Flow-scheduler route recovery telemetry now records per-channel route switches,
 the failed route a channel recovered from, and aggregate recovered-channel /
 switch counts, making alternate-route recovery measurable during load tests.
+`mesh-live-smoke` now also exercises a primary-route failure followed by an
+alternate-route success and reports the resulting route switch count.
 Endpoint ranking treats `capacity_limited` observations as a soft pressure
 penalty instead of a hard recent failure, enabling load spreading without
 marking the carrier unhealthy.