catalogue: a contribution reaches the port its own machine published, from any machine

The co-located fix could not reach a grant assembled for a consumer on another
machine: ContributionsFrom never sees a port map, so the proxy was told the
workload's software port and dialled a number that machine never published. The
consumer's own assignments are fetched where the grant is built and applied
there. The same fault as 038, one node over.

Claude-Session: https://claude.ai/code/session_01LrgweAeERJYBg88c5cKDzF

internal/catalogue/co_located_test.go

@@ -259,6 +259,33 @@ func TestAContributionFromAnotherMachineKeepsItsOwnPort(t *testing.T) {
 	}
 }
 
+// The cross-node half of the same fault: a grant assembled on the providing machine carries the
+// consumer's declared port until the CONSUMER's machine's assignments are applied to it. The
+// declaration layer cannot do it — those assignments are not this machine's, which is the line the
+// test above holds — so the grant layer is handed them and does it there.
+func TestAContributionIsRedirectedToWhereItsOwnMachinePublishedIt(t *testing.T) {
+	published := map[int]int{3000: 20000}
+
+	got := AtPublishedPort(map[string]any{"name": "git.example.tld", "port": 3000}, "forge", published)
+	if port, _ := asPort(got["port"]); port != 20000 {
+		t.Errorf("the proxy would dial a port that machine never published: %v", got["port"])
+	}
+	if got["name"] != "git.example.tld" {
+		t.Errorf("redirecting the port disturbed the rest of the contribution: %v", got)
+	}
+
+	// Idempotent, and silent about a port nobody moved: a module that pinned its own mapping has no
+	// assignment, and must come back exactly as it was written.
+	again := AtPublishedPort(got, "forge", published)
+	if port, _ := asPort(again["port"]); port != 20000 {
+		t.Errorf("applying it twice moved the port again: %v", again["port"])
+	}
+	pinned := AtPublishedPort(map[string]any{"port": 9070}, "office", published)
+	if port, _ := asPort(pinned["port"]); port != 9070 {
+		t.Errorf("a port the mesh never assigned was rewritten: %v", pinned["port"])
+	}
+}
+
 func asStrings(v any) []string {
 	listed, ok := v.([]any)
 	if !ok {