checker: resolve relative NS labels using the zone origin

NS hostnames stored in happyDomain's abstract.Origin service are encoded
relative to the zone apex (e.g. "ns0" instead of "ns0.example.com.").
normalizeNSList was calling dns.Fqdn() directly, turning "ns0" into the
useless single-label "ns0." rather than the correct FQDN.

Expose domain_name in ServiceOpts so happyDomain auto-fills the zone
apex at service scope, then use sdk.JoinRelative in normalizeNSList to
absolutize relative labels.  Absolute FQDNs (trailing dot) are kept
as-is so external nameservers round-trip safely.

checker/collect.go

@@ -32,7 +32,7 @@ func (p *authoritativeConsistencyProvider) Collect(ctx context.Context, opts sdk
 	data := &ObservationData{
 		Zone:       dns.Fqdn(zone),
 		HasSOA:     svc.SOA != nil,
-		DeclaredNS: normalizeNSList(svc.NameServers),
+		DeclaredNS: normalizeNSList(svc.NameServers, zone),
 		Results:    map[string]*NSResult{},
 	}
 	if svc.SOA != nil {
@@ -167,13 +167,17 @@ func loadZone(opts sdk.CheckerOptions, svc *originService) (string, error) {
 	return "", fmt.Errorf("no zone name provided (missing 'domain_name' option and SOA header)")
 }
 
-func normalizeNSList(ns []*dns.NS) []string {
+func normalizeNSList(ns []*dns.NS, origin string) []string {
 	out := make([]string, 0, len(ns))
 	for _, n := range ns {
 		if n == nil {
 			continue
 		}
-		out = append(out, strings.ToLower(dns.Fqdn(n.Ns)))
+		name := n.Ns
+		if !strings.HasSuffix(name, ".") {
+			name = sdk.JoinRelative(name, strings.TrimSuffix(origin, "."))
+		}
+		out = append(out, strings.ToLower(dns.Fqdn(name)))
 	}
 	sort.Strings(out)
 	return out

checker/collect_test.go

@@ -80,13 +80,15 @@ func TestDiffStringSets_Equal(t *testing.T) {
 }
 
 func TestNormalizeNSList(t *testing.T) {
+	// Relative labels (no trailing dot) are joined with the zone origin.
+	// Absolute FQDNs (trailing dot) are kept as-is.
 	in := []*dns.NS{
-		{Ns: "NS2.Example.COM"},
+		{Ns: "ns2"},
 		nil,
 		{Ns: "ns1.example.com."},
-		{Ns: "NS1.example.com"},
+		{Ns: "ns1"},
 	}
-	got := normalizeNSList(in)
+	got := normalizeNSList(in, "example.com.")
 	want := []string{"ns1.example.com.", "ns1.example.com.", "ns2.example.com."}
 	if !reflect.DeepEqual(got, want) {
 		t.Errorf("got %v, want %v", got, want)

checker/definition.go

@@ -110,6 +110,11 @@ func (p *authoritativeConsistencyProvider) Definition() *sdk.CheckerDefinition {
 					Label:    "Origin service",
 					AutoFill: sdk.AutoFillService,
 				},
+				{
+					Id:       "domain_name",
+					Label:    "Zone name",
+					AutoFill: sdk.AutoFillDomainName,
+				},
 			},
 		},
 		Rules: Rules(),