Measure VPN route recovery time

agents/rap-node-agent/internal/vpnruntime/fabric_transport.go

@@ -183,9 +183,11 @@ type fabricFlowQueue struct {
 	LastFailedRouteID            string
 	LastFailedRoutePolicyVersion string
 	LastFailedRouteGeneration    string
+	LastRouteFailureAt           time.Time
 	LastRecoveredFromRouteID     string
 	LastRecoveredNextHop         string
 	LastRouteSwitchAt            time.Time
+	LastRouteRecoveryMillis      int64
 	RouteSwitchCount             uint64
 	LastError                    string
 	ConsecutiveFailures          uint64
@@ -293,9 +295,11 @@ type FabricFlowStat struct {
 	LastFailedRouteID            string   `json:"last_failed_route_id,omitempty"`
 	LastFailedRoutePolicyVersion string   `json:"last_failed_route_policy_version,omitempty"`
 	LastFailedRouteGeneration    string   `json:"last_failed_route_generation,omitempty"`
+	LastRouteFailureAt           string   `json:"last_route_failure_at,omitempty"`
 	LastRecoveredFromRouteID     string   `json:"last_recovered_from_route_id,omitempty"`
 	LastRecoveredNextHop         string   `json:"last_recovered_next_hop,omitempty"`
 	LastRouteSwitchAt            string   `json:"last_route_switch_at,omitempty"`
+	LastRouteRecoveryMillis      int64    `json:"last_route_recovery_ms,omitempty"`
 	RouteSwitchCount             uint64   `json:"route_switch_count,omitempty"`
 	LastError                    string   `json:"last_error,omitempty"`
 	ConsecutiveFailures          uint64   `json:"consecutive_failures"`
@@ -702,6 +706,7 @@ func (s *FabricFlowScheduler) Snapshot() FabricFlowSchedulerSnapshot {
 			LastFailedRouteGeneration:    queue.LastFailedRouteGeneration,
 			LastRecoveredFromRouteID:     queue.LastRecoveredFromRouteID,
 			LastRecoveredNextHop:         queue.LastRecoveredNextHop,
+			LastRouteRecoveryMillis:      queue.LastRouteRecoveryMillis,
 			RouteSwitchCount:             queue.RouteSwitchCount,
 			LastError:                    queue.LastError,
 			ConsecutiveFailures:          queue.ConsecutiveFailures,
@@ -730,6 +735,9 @@ func (s *FabricFlowScheduler) Snapshot() FabricFlowSchedulerSnapshot {
 		if !qualityStats.LastUpdatedAt.IsZero() {
 			stat.QualityWindowLastUpdatedAt = qualityStats.LastUpdatedAt.UTC().Format(time.RFC3339Nano)
 		}
+		if !queue.LastRouteFailureAt.IsZero() {
+			stat.LastRouteFailureAt = queue.LastRouteFailureAt.UTC().Format(time.RFC3339Nano)
+		}
 		if !queue.LastRouteSwitchAt.IsZero() {
 			stat.LastRouteSwitchAt = queue.LastRouteSwitchAt.UTC().Format(time.RFC3339Nano)
 		}
@@ -755,9 +763,11 @@ func (s *FabricFlowScheduler) Snapshot() FabricFlowSchedulerSnapshot {
 			LastFailedRouteID:            stat.LastFailedRouteID,
 			LastFailedRoutePolicyVersion: stat.LastFailedRoutePolicyVersion,
 			LastFailedRouteGeneration:    stat.LastFailedRouteGeneration,
+			LastRouteFailureAt:           stat.LastRouteFailureAt,
 			LastRecoveredFromRouteID:     stat.LastRecoveredFromRouteID,
 			LastRecoveredNextHop:         stat.LastRecoveredNextHop,
 			LastRouteSwitchAt:            stat.LastRouteSwitchAt,
+			LastRouteRecoveryMillis:      stat.LastRouteRecoveryMillis,
 			RouteSwitchCount:             stat.RouteSwitchCount,
 			LastError:                    stat.LastError,
 			ConsecutiveFailures:          stat.ConsecutiveFailures,
@@ -1092,9 +1102,17 @@ func (s *FabricFlowScheduler) RecordRouteSuccessWithProvenance(channelID string,
 	failedRouteID := strings.TrimSpace(queue.LastFailedRouteID)
 	failedNextHop := strings.TrimSpace(queue.LastNextHop)
 	if failedRouteID != "" && strings.TrimSpace(routeID) != "" && failedRouteID != strings.TrimSpace(routeID) {
+		switchedAt := time.Now().UTC()
 		queue.LastRecoveredFromRouteID = failedRouteID
 		queue.LastRecoveredNextHop = failedNextHop
-		queue.LastRouteSwitchAt = time.Now().UTC()
+		queue.LastRouteSwitchAt = switchedAt
+		queue.LastRouteRecoveryMillis = 0
+		if !queue.LastRouteFailureAt.IsZero() {
+			queue.LastRouteRecoveryMillis = switchedAt.Sub(queue.LastRouteFailureAt).Milliseconds()
+			if queue.LastRouteRecoveryMillis < 0 {
+				queue.LastRouteRecoveryMillis = 0
+			}
+		}
 		queue.RouteSwitchCount++
 	}
 	queue.LastRouteID = routeID
@@ -1140,6 +1158,7 @@ func (s *FabricFlowScheduler) RecordRouteFailureWithProvenance(channelID string,
 	queue.LastFailedRouteID = routeID
 	queue.LastFailedRoutePolicyVersion = strings.TrimSpace(provenance.PolicyVersion)
 	queue.LastFailedRouteGeneration = strings.TrimSpace(provenance.Generation)
+	queue.LastRouteFailureAt = time.Now().UTC()
 	if fp := strings.TrimSpace(provenance.RecoveryPolicyFingerprint); fp != "" {
 		queue.RecoveryPolicyFingerprint = fp
 	}

agents/rap-node-agent/internal/vpnruntime/fabric_transport_test.go

@@ -1533,7 +1533,9 @@ func TestFabricClientPacketIngressIsolatesRouteFailoverPerLogicalChannel(t *test
 	if statA.LastRecoveredFromRouteID != "route-primary" ||
 		statA.LastRecoveredNextHop != "relay-primary" ||
 		statA.RouteSwitchCount != 1 ||
+		statA.LastRouteFailureAt == "" ||
 		statA.LastRouteSwitchAt == "" ||
+		statA.LastRouteRecoveryMillis < 0 ||
 		snapshot.FlowScheduler.RouteRecoveredChannelCount != 1 ||
 		snapshot.FlowScheduler.RouteSwitchCount != 1 {
 		t.Fatalf("route recovery telemetry = stat:%+v scheduler:%+v", statA, snapshot.FlowScheduler)

docs/architecture/DISTRIBUTED_FABRIC_NODE_PROTOCOL_PLAN.md

@@ -445,6 +445,8 @@ 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.
+Route recovery telemetry includes failure/switch timestamps and recovery
+duration in milliseconds for each recovered flow channel.
 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.