Rename mesh-control -> mesh-controller, substrate -> foundation

One name per thing, per the HQ glossary: the module/container/image/binary/repo
becomes mesh-controller, the seat the-controller, and the store+broker pair the
foundation (embedded base bundles, default template and example lock renamed with
their go:embed directives). No behaviour change — a pure vocabulary rename.

Claude-Session: https://claude.ai/code/session_01D6qtiYU3P9jk3pnAXyAFyx

cmd/mesh-controller/network_test.go

@@ -0,0 +1,78 @@
+package main
+
+import (
+	"context"
+	"strings"
+	"testing"
+
+	"github.com/novox/mesh-controller/internal/inventory"
+)
+
+// placementOf is what the mesh holds about where one node is.
+func placementOf(t *testing.T, ctx context.Context, inv *inventory.Inventory, name string) inventory.Overlay {
+	t.Helper()
+	placed, err := inv.Overlays(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, one := range placed {
+		if one.Name == name {
+			return one
+		}
+	}
+	t.Fatalf("%s is not placed at all", name)
+	return inventory.Overlay{}
+}
+
+// The sibling of `node public-domain`, and the worse one: a placement is three facts declared
+// together, so an invocation that said none of them took all three away — the endpoint every other
+// machine dials, the site, and the hub. A mesh whose hub was placed that way has no paths left.
+func TestPlacingANodeWithNothingSaidDoesNotUnplaceIt(t *testing.T) {
+	open := aMesh(t)
+	ctx := t.Context()
+	if err := overlayPlace(ctx, open.inventory,
+		[]string{"anchor", "--endpoint", "198.51.100.10:51820", "--site", "hosting", "--hub"}); err != nil {
+		t.Fatal(err)
+	}
+
+	err := overlayPlace(ctx, open.inventory, []string{"anchor"})
+	if err == nil {
+		t.Fatal("saying nothing unplaced the node instead of being refused")
+	}
+	if !strings.Contains(err.Error(), "--nothing") {
+		t.Errorf("the refusal does not say how to mean it: %v", err)
+	}
+
+	held := placementOf(t, ctx, open.inventory, "anchor")
+	if held.Endpoint != "198.51.100.10:51820" || held.Site != "hosting" || !held.Hub {
+		t.Fatalf("the placement was taken away by an invocation that was refused: %+v", held)
+	}
+}
+
+// Placing a machine with nothing set is a real thing to want — one that roams and opens every path
+// itself is exactly that — so it keeps a way to be said, by name.
+func TestPlacingANodeWithNothingIsAskedForByName(t *testing.T) {
+	open := aMesh(t)
+	ctx := t.Context()
+	if err := overlayPlace(ctx, open.inventory,
+		[]string{"anchor", "--endpoint", "198.51.100.10:51820", "--site", "hosting"}); err != nil {
+		t.Fatal(err)
+	}
+	if err := overlayPlace(ctx, open.inventory, []string{"anchor", "--nothing"}); err != nil {
+		t.Fatal(err)
+	}
+	held := placementOf(t, ctx, open.inventory, "anchor")
+	if held.Endpoint != "" || held.Site != "" || held.Hub {
+		t.Fatalf("--nothing did not place it with nothing: %+v", held)
+	}
+}
+
+// Both at once cannot be meant, so neither silently wins.
+func TestAPlacementAndNothingTogetherIsRefused(t *testing.T) {
+	open := aMesh(t)
+	ctx := t.Context()
+	if err := overlayPlace(ctx, open.inventory,
+		[]string{"anchor", "--site", "hosting", "--nothing"}); err == nil {
+		t.Fatal("a placement and --nothing together was accepted")
+	}
+}