Say mesh-grants.consumer-behind again only when the consumers behind change, not their counts

The counts change every pass, so a consumer that stays behind was said to the operator again at each pass. The
condition names the consumers alone; how far each is stays in the last pass.

Claude-Session: https://claude.ai/code/session_01NcbgfJ9Gum47zkFKWRaovL

modules/mesh-grants/grants_test.go

@@ -2309,6 +2309,12 @@ func TestGrants(t *testing.T) {
 			len(behind) == 0 || behind[len(behind)-1].State != asks.StateRaised || !strings.Contains(behind[len(behind)-1].Explanation, "EVENTS.b_mod-c") {
 			t.Fatalf("a consumer far behind: %+v, said %+v", res.Consumers, behind)
 		}
+		// Still behind at the next pass, by another count: the condition names the consumers alone, so it is not said again.
+		made["pending"] = grants.BehindBound + 50
+		n := len(behind)
+		if res = p.Compose(); len(res.Consumers.Behind) != 1 || len(behind) != n {
+			t.Fatalf("a consumer still behind by another count was said again: %+v", behind[n-1:])
+		}
 		made["pending"] = grants.BehindBound
 		res = p.Compose()
 		if len(res.Consumers.Behind) != 0 || behind[len(behind)-1].State != asks.StateCleared {

modules/mesh-grants/internal/grants/consumers.go

@@ -256,7 +256,15 @@ func (p *Part) sayBehind(st *ConsumersState) {
 	if p.Say == nil {
 		return
 	}
-	why := strings.Join(st.Behind, "; ")
+	// The consumers alone decide whether it is said again, never how far each is behind, which changes every pass: the
+	// counts stay in the last pass's consumers.behind (its state user-list, key pass), and the condition is not said again
+	// for them.
+	var names []string
+	for _, b := range st.Behind {
+		name, _, _ := strings.Cut(b, ": ")
+		names = append(names, name)
+	}
+	why := strings.Join(names, ", ")
 	p.holdMu.Lock()
 	defer p.holdMu.Unlock()
 	if p.behindKnown && why == p.behindSaid {
@@ -270,7 +278,7 @@ func (p *Part) sayBehind(st *ConsumersState) {
 		c.Summary = fmt.Sprintf("%d durable consumers are more than %d messages behind their stream's head", len(st.Behind), BehindBound)
 		c.Headline, c.Needs = "Messages pile up for a listener", "a look at the module that reads them"
 		c.Explanation = asks.NeedsYou + "a look. These consumers stayed far behind their stream's head at two passes " +
-			"running, so what is sent to their modules waits unread: " + why
+			"running, so what is sent to their modules waits unread (how far each is, in the grants part's last pass): " + why
 		c.Resolved = "every account consumer is back within the bound"
 	}
 	if p.Say(c) == nil {