v0.335.0: no app stop for a tier the agent will refuse because its host is busy (host_busy pre-check, R-921)

controller/internal/quiesce/quiesce.go

@@ -556,9 +556,10 @@ func (l *Loop) quiesceAndPollTiers(ctx context.Context, tiers []dueTier) error {
 	if len(tiers) == 0 {
 		return nil
 	}
-	// R-921: check first, stop second — a tier the agent will refuse (another tier's job in flight) stops
-	// no app. Pinned by TestR921_NoStopWhileAnotherTiersJobIsInFlight (precheck.go says what it cannot see).
-	if l.anotherTierInFlight(ctx, tiers[0].target) {
+	// R-921: check first, stop second — a tier the agent will refuse (another tier's job in flight, or its
+	// host-wide gate held) stops no app. Pinned by TestR921_NoStopWhileAnotherTiersJobIsInFlight and
+	// TestR921_NoStopWhileTheHostIsBusy (precheck.go).
+	if l.precheckSkips(ctx, tiers) {
 		return nil
 	}
 	running := l.stacks.RunningAppStacks()