node-tools: only a call pattern names a caller, and a fall-back for want of a responder is said (hq issue 365, review)

callerOn reads a caller only under the call kind, so a tool subscription ending
in a wildcard never yields one. A caller-named call that reached nobody is said
once per subject before it is asked on the old subject, so a runtime or grant
that drifted behind is seen rather than a quiet unproven. The caller tests wait
for their bundle's exit, which reads the launcher's restart pauses another test
sets.

node-tools/internal/bus/caller_test.go

@@ -56,3 +56,17 @@ func TestTheCallerIsTheLastTokenOfTheSubjectTheCallArrivedOn(t *testing.T) {
 		}
 	}
 }
+
+// Only a pattern of the `call` kind names a caller: a `tool` subscription with a wildcard last — a node seat's
+// verb on any machine, say — never yields one, whatever token a call arrived with.
+func TestAToolPatternNeverYieldsACaller(t *testing.T) {
+	for pattern, subject := range map[string]string{
+		"mesh.mod.ledger.tool.who.*":     "mesh.mod.ledger.tool.who.controller",
+		"mesh.seat.node-desk.tool.who.*": "mesh.seat.node-desk.tool.who.shanks~node-tools",
+		"mesh.mod.ledger.event.*":        "mesh.mod.ledger.event.controller",
+	} {
+		if got := callerOn(pattern, subject); got != "" {
+			t.Errorf("%s on %s yielded caller %q", pattern, subject, got)
+		}
+	}
+}