Judge S21 by time since the first failing report while the machine is heard, not by how many reports said it (issue 233 review)

cmd/mesh-controller/signals.go

@@ -255,9 +255,10 @@ var signalsTable = []signalRow{
 			return newestOf(f.bus.waits, func(w busWaitFacts) time.Time { return w.since })
 		}},
 	{Row: "S21", Signal: "a clean apply", Emitter: "node-engine", Trigger: "each report of a declaration refused or applied only in part (novox/hq issue 233)",
-		Bound: "one apply interval (5 min) past the first report of the same failure, over at least two reports; not " +
-			"while the machine is silent or asleep; naming the refusal, or the package manager that does not answer " +
-			"with its words; cleared by a clean apply",
+		Bound: "one apply interval (5 min) past the first report of the same failure, judged by time while the machine " +
+			"is heard — the node-engine says a re-apply only when how it went changed; not while it is silent or " +
+			"asleep; naming the refusal, or the package manager that does not answer with its words; cleared by the " +
+			"clean apply it then says",
 		Kind: kindApplyFailing, Severity: conditions.Warning, Phase: 2,
 		needs: func(f *signalFacts) error { return f.doingErr }, watch: watchApplyFailing,
 		newest: func(f *signalFacts) time.Time {