A routed name resolves to the node whose proxy serves it, never to a provider merely told it (hq 178)

The names region attributed a composed name to whichever labelled contribution a map yielded last.
A dashboard contributes its label to its route and to the identity provider, which must know the
public name for a redirect; so on one plan grafana.<domain> pointed at the proxy's machine and on
the next at the identity provider's, and the whole region flipped with it (forge issue 227). And a
module routed several times contributed no name at all, because the single-value reading of its
contributions is empty for the many shape.

Now every node's resolution is read first and the names are attributed across them at once: the
terminus serves the name — the provider that is not itself published under a labelled name through
another — walked in order, so one mesh yields one region. Name-agnostic, structural, deterministic.

internal/catalogue/names_served_test.go

@@ -0,0 +1,99 @@
+package catalogue
+
+import (
+	"testing"
+)
+
+// The mesh of forge issue 227 (novox/hq issue 178): a dashboard on the home server contributes its
+// label to the route its proxy serves AND to the identity provider on the control node, which must
+// know the dashboard's public name to compose a redirect. Both contributions carry the composed
+// name; only the proxy serves it.
+func twoNodesOneName(t *testing.T) (map[string]Resolution, map[string]SettingsBy) {
+	t.Helper()
+	catalogue := shelf(
+		Manifest{Module: "route-adapter", Version: "1", Provides: Offers("route"),
+			Serves: map[string]map[string]any{"route": {}}, Receives: map[string]string{"route": "/etc/adapter/mesh.json"}},
+		Manifest{Module: "route-proxy", Version: "1", Provides: Offers("route"),
+			Serves: map[string]map[string]any{"route": {}}, Receives: map[string]string{"route": "/etc/proxy/mesh.json"}},
+		Manifest{Module: "keycloak", Version: "1", Provides: FromAnywhere("oidc-client"),
+			Serves:   map[string]map[string]any{"oidc-client": {"token-path": "/token"}},
+			Receives: map[string]string{"oidc-client": "/etc/keycloak/clients.json"},
+			Listens:  []Listening{{Port: 8080, From: FromMesh, Why: "the login page"}},
+			// Published through the proxy itself: the identity provider is routed, not a router.
+			Contributes: map[string]map[string]any{"route": {"label": "login", "endpoint": "web", "port": 8080}}},
+		Manifest{Module: "grafana", Version: "1",
+			Listens: []Listening{{Port: 3000, From: FromMesh, Why: "dashboards"}},
+			Contributes: map[string]map[string]any{
+				"route":       {"label": "grafana", "endpoint": "web", "port": 3000},
+				"oidc-client": {"label": "grafana", "endpoint": "web", "port": 3000, "callback": "/login"},
+			}},
+	)
+	home := withDomain("home.example")
+	home.Name, home.At = "home-server", "home-server.internal"
+	control := withDomain("control.example")
+	control.Name, control.At = "anchor", "anchor.internal"
+
+	onHome, err := Resolve(catalogue, []string{"grafana", "route-adapter"}, home, World{
+		Offered: map[string][]Provider{"oidc-client": {{Node: "anchor", At: "anchor.internal", Module: "keycloak"}}},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	onControl, err := Resolve(catalogue, []string{"keycloak", "route-proxy"}, control, World{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	return map[string]Resolution{"home-server": onHome, "anchor": onControl},
+		map[string]SettingsBy{"home-server": {}, "anchor": {}}
+}
+
+func TestANameResolvesToTheNodeWhoseProxyServesIt(t *testing.T) {
+	plans, settings := twoNodesOneName(t)
+	// Many times, because the fault was map order: one plan said one node, the next the other.
+	for i := 0; i < 25; i++ {
+		served, err := NamesServed(plans, settings)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if served["grafana.home.example"] != "home-server" {
+			t.Fatalf("run %d: the dashboard's name is served by %q, and its proxy is on the home server: %v",
+				i, served["grafana.home.example"], served)
+		}
+		if served["login.control.example"] != "anchor" {
+			t.Fatalf("run %d: the identity provider's own name is served by its proxy on the control node: %v", i, served)
+		}
+		if _, leaked := served["grafana.control.example"]; leaked {
+			t.Fatalf("a name composed for the identity provider's benefit is not one it serves: %v", served)
+		}
+	}
+}
+
+// A module that is routed several times names each route (ADR 0094's sibling for contributes);
+// every one of them is a name the mesh must resolve, and none reached the names region before.
+func TestEveryRouteOfAModuleWithSeveralIsANameServed(t *testing.T) {
+	catalogue := shelf(
+		Manifest{Module: "route-proxy", Version: "1", Provides: Offers("route"),
+			Serves: map[string]map[string]any{"route": {}}, Receives: map[string]string{"route": "/etc/proxy/mesh.json"}},
+		Manifest{Module: "photos", Version: "1",
+			Listens: []Listening{{Port: 8102, From: FromMesh, Why: "web"}, {Port: 9102, From: FromMesh, Why: "api"}},
+			ContributesMany: map[string]map[string]map[string]any{"route": {
+				"site": {"label": "photos", "endpoint": "web", "port": 8102},
+				"api":  {"label": "photos-api", "endpoint": "api", "port": 9102},
+			}}},
+	)
+	node := withDomain("control.example")
+	node.Name, node.At = "anchor", "anchor.internal"
+	plan, err := Resolve(catalogue, []string{"photos", "route-proxy"}, node, World{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	served, err := NamesServed(map[string]Resolution{"anchor": plan}, map[string]SettingsBy{"anchor": {}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, name := range []string{"photos.control.example", "photos-api.control.example"} {
+		if served[name] != "anchor" {
+			t.Fatalf("%s is not served by its proxy: %v", name, served)
+		}
+	}
+}