Let a drain lapse, bound the gate's wait on the controller's clock, keep a busy wait out of apply time

Review of #283: a drain whose replacement was withdrawn held the agent for
ever with its health green; the gate trusted the engine's until; a machine
of the rest waiting at the bound read as silent and its apply time held the
wait; an unknown mesh-builder word exited 0; plan said nothing of a busy an
older engine is not sent; and a node with a report and no send broke the
reading of every last report (the store test's NULL).

cmd/mesh-controller/plan.go

@@ -1059,6 +1059,25 @@ func engineReadsBusy(ctx context.Context, inv *inventory.Inventory, node string)
 	return had && stated.Contract >= link.BusyContract, nil
 }
 
+// busyNotSent is, for a node-engine that does not read a container's busy, each container whose module declares
+// one: not sent it, so replaced at once while it may hold work (novox/hq ADR 0335). Nothing for one that reads it.
+func busyNotSent(modules []catalogue.Manifest, reads bool) []string {
+	if reads {
+		return nil
+	}
+	var out []string
+	for _, m := range modules {
+		for _, r := range m.Resources {
+			if _, has := r[catalogue.BusyField]; has {
+				out = append(out, fmt.Sprintf("%s.%v declares busy, and this node-engine does not read it yet (its "+
+					"statement's contract is below %d): not sent, so the container is replaced at once, busy or not "+
+					"(novox/hq ADR 0335)", m.Module, r["id"], link.BusyContract))
+			}
+		}
+	}
+	return out
+}
+
 // zonesInTheMesh is every zone a module in the mesh declares, where the mesh placed it (novox/hq ADR
 // 0199): the zone settled from that node's settings, the node's private address, the port the
 // answering listen is published on there.
@@ -1466,6 +1485,15 @@ func planCommand(ctx context.Context, args []string) error {
 	for _, line := range unboundLines(plan) {
 		fmt.Println(line)
 	}
+	// And a container's busy that this machine's node-engine is too old to be sent (novox/hq ADR 0335): its
+	// container is replaced at once, as before. A statement that cannot be read is said as such.
+	if reads, err := engineReadsBusy(ctx, open.inventory, args[0]); err != nil {
+		fmt.Printf("%s: whether its node-engine reads a container's busy could not be read: %v\n", args[0], err)
+	} else {
+		for _, line := range busyNotSent(plan.Modules, reads) {
+			fmt.Printf("%s: %s\n", args[0], line)
+		}
+	}
 	declared, err := declarationFor(ctx, open, args[0], plan, settings)
 	if err != nil {
 		return err