S4 catalog-ready-on-a-fresh-mesh: with the registrations and the gate's source answered and naming no branch, Ready is nil and the view is empty

Builds: design 47 G A-368 (G-22-lead-answers-2.md), start-waits.md S4

Claude-Session: https://claude.ai/code/session_01NcbgfGKaxw984XyAPfLm4h

modules/mesh-delivery-contracts/go/clients/meshcatalogclient/entry.go

@@ -12,10 +12,16 @@ import (
 )
 
 // Ready is nil once every watched branch has its first view (`none-yet` counting as one), else says what it waits for
-// (design 47 G §614, A-103): a part acts on nothing until then.
+// (design 47 G §614, A-103): a part acts on nothing until then. On a fresh mesh, where the registrations and the gate's source are both
+// answered and name no branch, it is nil too: the trunk is `none-yet` (A-368).
 func (b *Branches) Ready() error {
 	followed := b.Followed()
 	if len(followed) == 0 {
+		// A fresh mesh: the registrations and the gate's source are both answered and name no branch, so the trunk is `none-yet`
+		// and the view is empty (design 47 G, A-368).
+		if b.namesNoBranch() {
+			return nil
+		}
 		return fmt.Errorf("the catalog half names no watched branch yet (the registrations of the seat %s are asked until they answer)", seat.Seat)
 	}
 	var waiting []string
@@ -34,6 +40,28 @@ func (b *Branches) Ready() error {
 	return nil
 }
 
+// namesNoBranch says the first view of the registrations is in and, while the gate's source is followed, so is its, and
+// neither names a branch (none is followed).
+func (b *Branches) namesNoBranch() bool {
+	select {
+	case <-b.Registrations.Ready():
+	default:
+		return false
+	}
+	b.mu.Lock()
+	s := b.source
+	b.mu.Unlock()
+	if s == nil {
+		return true
+	}
+	select {
+	case <-s.Follower.Ready():
+		return true
+	default:
+		return false
+	}
+}
+
 // Entry is a module's entry at the trunk: the module's own registration decides, so the branch followed first, which lists
 // the module, is the one read (design 47 G A-103). An error says a watched branch has no first view yet, never "no module".
 func (b *Branches) Entry(module string) (seat.CatalogEntry, bool, error) {

modules/mesh-delivery-contracts/go/clients/meshcatalogclient/entry_test.go

@@ -94,3 +94,44 @@ func TestTheBranchFollowerGivesEveryPartItsEntryHelpers(t *testing.T) {
 		t.Error("a released entry kept its finding")
 	}
 }
+
+// A-368 (design 47 G, C6): on a fresh mesh, where neither the registrations nor the gate's source name a branch, the catalog half
+// counts the trunk as `none-yet`: Ready is nil once both are answered, and the view is empty (Entry finds no module); until
+// both answer, no part is ready.
+func TestAMeshThatNamesNoBranchIsReadyWithAnEmptyView(t *testing.T) {
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	for _, c := range []struct {
+		name  string
+		start []string // the followers started, by the name they are adopted under
+		ready bool
+	}{
+		{"nothing answered", nil, false},
+		{"only the registrations answered", []string{"mesh-catalog.registrations"}, false},
+		{"only the gate's source answered", []string{"mesh-delivery.source"}, false},
+		{"both answered", []string{"mesh-catalog.registrations", "mesh-delivery.source"}, true},
+	} {
+		t.Run(c.name, func(t *testing.T) {
+			seats := &fakeSeats{regs: map[string][]string{}}
+			w := &fakeWiring{adopted: map[string]*views.Follower{}, hears: map[string]func(context.Context, []byte) error{}}
+			b, err := NewBranches(w, seats.call)
+			if err != nil {
+				t.Fatal(err)
+			}
+			for _, name := range c.start {
+				f, _ := w.get(name)
+				if err := f.Start(ctx); err != nil {
+					t.Fatal(err)
+				}
+			}
+			if err := b.Ready(); (err == nil) != c.ready {
+				t.Fatalf("Ready = %v, want ready %v", err, c.ready)
+			}
+			if c.ready {
+				if e, found, err := b.Entry("m"); err != nil || found {
+					t.Errorf("Entry = %v, %v, %v: want an empty view, no error", e, found, err)
+				}
+			}
+		})
+	}
+}