mesh-delivery-sdk graph: a reader of the seat list waits for its holder by the verb edge and a foundation part on a cycle with it does not (D-31; ADR 0614 §2, ADR 0636 §1; issue 1966)

Claude-Session: https://claude.ai/code/session_01NcbgfFSnn24M3GcqttoU7i

sdk/graph/graph_test.go

@@ -15,6 +15,7 @@ import (
 // TestGraphEdges: the module graph's cycle, dependents and providers, each from the edges alone (ADR 0603 §2, ADR 0604 §1).
 func TestGraphEdges(t *testing.T) {
 	t.Run("a node's value", nodeValues)
+	t.Run("a reader of the seat list waits for its holder", readersOfTheSeatList)
 	fp := "src2:" + strings.Repeat("b", 64)
 	node := func(repository, path string, edit func(*Node)) Node {
 		n := Node{FP: fp, Repository: repository, Path: path}
@@ -252,3 +253,41 @@ func nodeValues(t *testing.T) {
 		}
 	}
 }
+
+// readersOfTheSeatList (D-31): a module whose manifest invokes the seat mesh-catalog's seat-definitions waits, by the verb
+// edge, for the module that claims the seat and serves the verb, so the delivery plan puts the holder first (ADR 0614 §2); a
+// foundation part the holder itself invokes lies on a cycle with it and the edge is left out, so the part is carried by the
+// bootstrapped three until the holder's new build runs (ADR 0636 §1).
+func readersOfTheSeatList(t *testing.T) {
+	const list = "seat:mesh-catalog.seat-definitions"
+	fp := "src2:" + strings.Repeat("c", 64)
+	node := func(edit func(*Node)) Node {
+		n := Node{FP: fp, Repository: "novox/mesh-delivery", Path: "modules/x"}
+		edit(&n)
+		return n
+	}
+	g := Graph{
+		"indexer": node(func(n *Node) {
+			n.Serves = []string{list, "seat:mesh-catalog.modules"}
+			n.Invokes = []string{"seat:node-engine.composed"}
+		}),
+		"checker":    node(func(n *Node) { n.Invokes = []string{list} }),
+		"node-agent": node(func(n *Node) { n.Invokes = []string{list}; n.Serves = []string{"seat:node-engine.composed"} }),
+	}
+	if got := g.Servers(list); !reflect.DeepEqual(got, []string{"indexer"}) {
+		t.Errorf("servers of the seat list = %v", got)
+	}
+	if got := g.Before("checker"); !reflect.DeepEqual(got, []string{"indexer"}) {
+		t.Errorf("the checker waits for %v, want the indexer", got)
+	}
+	g.LeaveOut()
+	if got := g.Before("checker"); !reflect.DeepEqual(got, []string{"indexer"}) {
+		t.Errorf("after the cycles are left out the checker waits for %v, want the indexer", got)
+	}
+	if got := g["node-agent"].LeftOut; !reflect.DeepEqual(got, []string{list}) {
+		t.Errorf("the node-agent leaves out %v, want the seat list (a cycle with the holder)", got)
+	}
+	if got := g.Before("node-agent"); len(got) != 0 {
+		t.Errorf("the node-agent waits for %v, want nothing: the bootstrap carries it", got)
+	}
+}