process: a bucket missing at a part's start is bound when the bus says it was created, keeping what was written meanwhile; buscompose grants each principal the creation of the buckets it may bind (issue 1790)

Since the grants part creates a manifest's buckets after a delivery (ADR 0547), a module restarted by that
delivery can open a new state before it exists; OptionalBucket answered nil and the part never looked again
(mesh-delivery's checker and builder, state hearing, 2026-10-26). AwaitBucket binds on the server's
STREAM.CREATED advisory, or at the next use, and writes the latest value kept per key. The copied composer's
agreement test leaves that one row out: the controller's list is no longer loaded since the take-over.

go/delivery/buildrun/lostask.go

@@ -3,6 +3,7 @@ package buildrun
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"strconv"
 	"strings"
@@ -13,6 +14,7 @@ import (
 
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 	"git.novox.be/novox/mesh-sdk/go/health"
+	"git.novox.be/novox/mesh-sdk/go/process"
 )
 
 // **An ask the build seat gave up on ends its step** (novox/hq issue 734). A build seat's worker offers an ask
@@ -458,9 +460,15 @@ func (h *DeadLetterHearing) tell() {
 // health tool reads.
 const HearingState = "hearing"
 
+// HearingKeeper is where a Hearing is kept: a jetstream.KeyValue, or a process.AwaitedBucket for a state that may not be
+// on the bus at the part's start (issue 1790), which keeps the latest until it appears and answers process.ErrNotYet.
+type HearingKeeper interface {
+	Put(ctx context.Context, key string, value []byte) (uint64, error)
+}
+
 // SayHearing is a DeadLetterHearing's said that keeps each Hearing in kv under HearingKey; nil kv keeps nothing and
-// says so once.
-func SayHearing(ctx context.Context, kv jetstream.KeyValue, logf func(string, ...any)) func(Hearing) {
+// says so once. A write kv keeps for later (process.ErrNotYet) is not an error: the awaited bucket said it waits.
+func SayHearing(ctx context.Context, kv HearingKeeper, logf func(string, ...any)) func(Hearing) {
 	if kv == nil {
 		if logf != nil {
 			logf("whether %s is heard is not kept: the state %s is not there, so the health tool cannot say it", DeadLettersStream, HearingState)
@@ -472,7 +480,7 @@ func SayHearing(ctx context.Context, kv jetstream.KeyValue, logf func(string, ..
 		if err == nil {
 			_, err = kv.Put(ctx, HearingKey, data)
 		}
-		if err != nil && logf != nil {
+		if err != nil && !errors.Is(err, process.ErrNotYet) && logf != nil {
 			logf("whether %s is heard could not be kept: %v", DeadLettersStream, err)
 		}
 	}