Ask the operator only once the bus holds the controller's grant to ask (hq issue 353)

The grant is composed from the router's assignment and reaches the bus when its machine is next
pushed. Between assign and push the record said a router was here and the bus refused every ask
(seven refusals on 2026-10-09, 17:54 to 17:56). The asker now judges, as a push does, whether the
bus's machine was last sent the user list composed now; while it was not, nothing is published, it
is said once, and the conditions that need the operator are raised as undelivered, naming the push
that carries the grant.

cmd/mesh-controller/asker_wire.go

@@ -11,6 +11,7 @@ import (
 	"fmt"
 	"sort"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/nats-io/nats.go"
@@ -234,6 +235,38 @@ func routerHereIn(inv *inventory.Inventory) func(ctx context.Context) (bool, err
 	}
 }
 
+// grantHeldIn says whether the bus holds the controller's grant to ask (novox/hq issue 353): the user list the
+// machine holding the bus was last sent is the one the mesh composes now (brokerBehind, the same judgement a
+// push makes to send that machine first). While it is behind, the controller's ask is refused by the bus,
+// whatever the record says of the router, so nothing is asked and the operator is told to push that machine.
+// Judged at most every grantLookEvery: composing the list resolves the bus's machine whole.
+func grantHeldIn(open *stores) func(ctx context.Context) (bool, string, error) {
+	var mu sync.Mutex
+	var at time.Time
+	var held bool
+	var why string
+	return func(ctx context.Context) (bool, string, error) {
+		mu.Lock()
+		defer mu.Unlock()
+		if !at.IsZero() && time.Since(at) < grantLookEvery {
+			return held, why, nil
+		}
+		machine, behind, err := brokerBehind(ctx, open, nil)
+		if err != nil {
+			return false, "", err
+		}
+		at, held, why = time.Now(), !behind, ""
+		if behind {
+			why = fmt.Sprintf("the bus's user list on %s is behind what the mesh composes, so the bus has not been "+
+				"given the controller's grant to ask; `push %s` carries it", machine, machine)
+		}
+		return held, why, nil
+	}
+}
+
+// grantLookEvery is how often the bus's user list is judged against the one its machine was last sent.
+const grantLookEvery = 30 * time.Second
+
 // channelsIn is what the channels are now, as a fingerprint: each module claiming a kind of the channel
 // bench, where, promising what, and whether of its own account. An ask the router refused is asked again
 // once this changes.
@@ -287,6 +320,7 @@ func startAsking(ctx context.Context, open *stores, server *link.Server, conn *n
 		},
 		routerRecord: routerRecordOf(conn, open.inventory),
 		routerHere:   routerHereIn(open.inventory),
+		grantHeld:    grantHeldIn(open),
 		channels:     channelsIn(open.inventory),
 		raise: func(ctx context.Context, obs []conditions.Observation) error {
 			return keeper.Reconcile(ctx, sourceAsker, obs)