The checker's judge counts the old sections from the trunk case as the indexer does, so a change adding a section at 0 is refused at the merge check (issue 1966 D4)

modules/mesh-delivery-indexer/judge/judge.go

@@ -189,6 +189,7 @@ const Unnamed = "(between manifests)"
 func Request(r composer.Request) (composer.Verdict, error) {
 	v := composer.Verdict{V: composer.Version, SDK: Identity()}
 	seen := map[string]bool{}
+	counts := trunkOldSections(r)
 	for _, c := range r.Cases {
 		if seen[c.Name] {
 			return composer.Verdict{}, fmt.Errorf("the case %q is named twice", c.Name)
@@ -201,7 +202,7 @@ func Request(r composer.Request) (composer.Verdict, error) {
 			}
 			raws[name] = m.Raw
 		}
-		refused, unnamed := Shelf(raws, r.Predefined, 0)
+		refused, unnamed := ShelfCounting(raws, r.Predefined, 0, counts)
 		cv := composer.CaseVerdict{Name: c.Name, Manifests: map[string]composer.ManifestRead{}}
 		for name := range raws {
 			if problems := refused[name]; len(problems) > 0 {
@@ -218,6 +219,39 @@ func Request(r composer.Request) (composer.Verdict, error) {
 	return v, nil
 }
 
+// TrunkCase is the case of a request holding the catalogue as the trunk holds it (the checker's JudgeTrunk).
+const TrunkCase = "trunk"
+
+// trunkOldSections counts the old sections the modules accepted at the trunk use, as the indexer counts them from its
+// verdicts (issue 1966 D4, ADR 0595 §11): a change is refused at the merge check exactly as at take-in (judged once, ADR
+// 0578). Nil where the request holds no trunk case, which refuses no use of a section.
+func trunkOldSections(r composer.Request) OldSectionCounts {
+	for _, c := range r.Cases {
+		if c.Name != TrunkCase {
+			continue
+		}
+		raws := map[string][]byte{}
+		for name, m := range c.Manifests {
+			if len(m.Raw) > 0 {
+				raws[name] = m.Raw
+			}
+		}
+		refused, _ := Shelf(raws, r.Predefined, 0)
+		var accepted []catalogue.Manifest
+		for name, raw := range raws {
+			if len(refused[name]) > 0 {
+				continue
+			}
+			if m, err := catalogue.Decode(raw); err == nil {
+				m.Module = name
+				accepted = append(accepted, m)
+			}
+		}
+		return CountOldSections(accepted)
+	}
+	return nil
+}
+
 var (
 	identityOnce sync.Once
 	identity     string

modules/mesh-delivery-indexer/judge/judge_test.go

@@ -86,6 +86,27 @@ func TestTheJudge(t *testing.T) {
 		v.Cases[0].Manifests["b"].Accepted || !strings.Contains(v.Cases[0].Manifests["b"].Refused, `requires "amqp"`) {
 		t.Fatalf("request: %+v %v", v, err)
 	}
+	// 1966/AC11: the checker's judge counts the old sections from the trunk case as the indexer does from its verdicts (the
+	// foundation left out): a change adding logs where no trunk module uses them is refused, the foundation's accepted, and
+	// state, which a trunk module uses, is accepted.
+	old := composer.Request{V: composer.Version, Cases: []composer.Case{
+		{Name: "change", Manifests: map[string]composer.Manifest{
+			"user":        {Raw: json.RawMessage(`{"module":"user","version":"1","state":["x"]}`)},
+			"late":        {Raw: json.RawMessage(`{"module":"late","version":"1","logs":[{"name":"l"}]}`)},
+			"newer":       {Raw: json.RawMessage(`{"module":"newer","version":"1","state":["y"]}`)},
+			"mesh-grants": {Raw: json.RawMessage(`{"module":"mesh-grants","version":"1","logs":[{"name":"l"}]}`)}}},
+		{Name: "trunk", Manifests: map[string]composer.Manifest{
+			"user":        {Raw: json.RawMessage(`{"module":"user","version":"1","state":["x"]}`)},
+			"mesh-grants": {Raw: json.RawMessage(`{"module":"mesh-grants","version":"1","logs":[{"name":"l"}]}`)}}}}}
+	ov, err := Request(old)
+	if err != nil {
+		t.Fatal(err)
+	}
+	got := ov.Cases[0].Manifests
+	if got["late"].Accepted || !strings.Contains(got["late"].Refused, "late uses the old section logs") ||
+		!got["newer"].Accepted || !got["user"].Accepted || !got["mesh-grants"].Accepted {
+		t.Errorf("the change's old sections: %+v", got)
+	}
 	r.Cases[0].Manifests["c"] = composer.Manifest{Digest: strings.Repeat("a", 64)}
 	if _, err := Request(r); err == nil {
 		t.Fatal("a manifest left as a digest was judged")