IX30 (part 2): a revision's one claim of the seat node-engine is accepted, a second and none are refused

Builds: design 47 G §508, §527 (IX30)

Claude-Session: https://claude.ai/code/session_01JG73KEq4zoDfM9WtYpcQgZ

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

@@ -160,7 +160,7 @@ func judgedByRequest(t *testing.T, shelf catalogue.Shelf, known KnownPackages) s
 	if known != nil {
 		names = append([]string{}, slices.Sorted(maps.Keys(known))...)
 	}
-	c := composer.Case{Name: "change", Manifests: map[string]composer.Manifest{}}
+	c := composer.Case{Name: "change", Manifests: map[string]composer.Manifest{"node-engine": {Raw: []byte(engineManifest("node-engine"))}}}
 	for name, m := range shelf {
 		raw, err := json.Marshal(m)
 		if err != nil {

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

@@ -108,3 +108,31 @@ func findingEventsProblems(module string, e catalogue.BusStateEntry) []string {
 	slices.Sort(problems)
 	return problems
 }
+
+// NodeEngineSeat is the seat the node-engine claims as one module (design 47 G §508).
+const NodeEngineSeat = "node-engine"
+
+// nodeEngineClaimProblems are the refusals of a revision's claims of the seat `node-engine`: one module claims it, a second
+// is refused naming both (§508), and a revision in which none does is refused naming the seat (§527), since the
+// node-engine's own module is read from the module whose entry claims it. A revision whose seat list lacks the seat is
+// not judged.
+func nodeEngineClaimProblems(shelf catalogue.Shelf) []string {
+	if _, known := catalogue.SeatNamed(NodeEngineSeat); !known {
+		return nil
+	}
+	var holders []string
+	for module, m := range shelf {
+		if slices.ContainsFunc(m.Claims, func(c catalogue.Claim) bool { return c.Name == NodeEngineSeat }) {
+			holders = append(holders, module)
+		}
+	}
+	slices.Sort(holders)
+	switch {
+	case len(holders) == 0:
+		return []string{fmt.Sprintf("no module of the revision claims the seat %s; the node-engine's own module is the one that does "+
+			"(design 47 G §527)", NodeEngineSeat)}
+	case len(holders) > 1:
+		return []string{fmt.Sprintf("%s claim the seat %s, which one module claims (design 47 G §508)", strings.Join(holders, " and "), NodeEngineSeat)}
+	}
+	return nil
+}

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

@@ -170,6 +170,7 @@ func Between(shelf catalogue.Shelf, longestMachine int, known KnownPackages) []s
 	between = append(between, PackagesCatalogueProblems(shelf, known)...)
 	between = append(between, IdentityProblems(shelf, longestMachine)...)
 	between = append(between, DataProblems(shelf)...)
+	between = append(between, nodeEngineClaimProblems(shelf)...)
 	sort.Strings(between)
 	return slices.Compact(between)
 }

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

@@ -2,13 +2,13 @@ package judge
 
 import (
 	"encoding/json"
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
 	"reflect"
 	"strings"
 	"testing"
 
 	"git.novox.be/novox/mesh-delivery/sdk/composer"
 	"git.novox.be/novox/mesh-networking/modules/mesh-wireguard/go/overlay"
-	"git.novox.be/novox/mesh-sdk/go/catalogue"
 )
 
 // The judge (novox/hq ADR 0578 §1): a manifest alone is accepted, or refused with each problem; an unknown field is
@@ -46,7 +46,7 @@ func TestTheJudge(t *testing.T) {
 				"enrolment": `{"module":"enrolment","version":"1.0","claims":[{"name":"enrolment","scope":"mesh","serves":["issue","again"]}],` +
 					`"tools":["enrolment_first_views","enrolment_first_view_again"]}`}},
 	} {
-		raws := map[string][]byte{}
+		raws := map[string][]byte{"node-engine": []byte(engineManifest("node-engine"))} // a revision has one claim of the seat node-engine (§527)
 		for k, v := range row.raws {
 			raws[k] = []byte(v)
 		}
@@ -153,3 +153,47 @@ func versioned(t *testing.T, raw []byte) []byte {
 	}
 	return out
 }
+
+// engineManifest is the manifest of a module that claims the seat node-engine, serving every verb the seat promises
+// (design 47 G §508, §527).
+func engineManifest(module string) string {
+	seat, _ := catalogue.SeatNamed(NodeEngineSeat)
+	var verbs []string
+	for _, v := range seat.Serves {
+		verbs = append(verbs, `"`+v.Name+`"`)
+	}
+	return `{"module":"` + module + `","version":"1.0","claims":[{"name":"node-engine","scope":"node","serves":[` + strings.Join(verbs, ",") + `]}]}`
+}
+
+// Design 47 G §508, §527: one module of a revision claims the seat node-engine; a second is refused naming both, and none
+// refuses the revision naming the seat.
+func TestTheRevisionHasOneClaimOfTheNodeEngine(t *testing.T) {
+	for _, row := range []struct {
+		name string
+		raws map[string]string
+		want string // empty: accepted
+	}{
+		{"one claim", map[string]string{"engine": engineManifest("engine")}, ""},
+		{"two claims", map[string]string{"engine": engineManifest("engine"), "other": engineManifest("other")},
+			"claim the seat node-engine"},
+		{"none", map[string]string{"ok": `{"module":"ok","version":"1.0"}`}, "claims the seat node-engine"},
+	} {
+		raws := map[string][]byte{}
+		for k, v := range row.raws {
+			raws[k] = []byte(v)
+		}
+		refused, unnamed := Shelf(raws, nil, 0)
+		got := strings.Join(append(unnamed, flat(refused)...), "\n")
+		if (row.want == "") != (got == "") || !strings.Contains(got, row.want) {
+			t.Errorf("%s: refused %q, want %q", row.name, got, row.want)
+		}
+	}
+}
+
+func flat(refused map[string][]string) []string {
+	var out []string
+	for _, p := range refused {
+		out = append(out, p...)
+	}
+	return out
+}

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

@@ -4638,13 +4638,6 @@ func claimProblems(m catalogue.Manifest) []string {
 	}
 
 	for _, c := range m.Claims {
-		if s, known := catalogue.SeatNamed(c.Name); known && s.HeldByTheEngine {
-			// The node's engine holds it on every node, and no module may (novox/hq ADR 0563 §1): a module answering
-			// root-free or a hand-over would be an agent answering it.
-			problems = append(problems, fmt.Sprintf("%s claims %s, which every node's engine holds itself and no "+
-				"module may (novox/hq ADR 0563 §1)", m.Module, c.Name))
-			continue
-		}
 		if _, known := catalogue.SeatNamed(c.Name); known {
 			// **A seat's scope and what it delivers are not judged here** (novox/hq ADR 0122).
 			// This function runs wherever a manifest is parsed, and one of those places is the