Send an approved settings layer by a walk at once, so the operator's Approve is the act that takes effect (issue 641, ADR 0344)

The warrant set the layer and left the push as a second act nobody took: the
operator approved a betterbird change on Telegram and nothing reached g14.
Now the warrant opens a settings walk: the machines the layer reaches, one at
a time, the module judged on each at its gate, its end told once through
plan-moved. The ask and the proposer's answer say so instead of naming push.

cmd/mesh-controller/release.go

@@ -616,6 +616,10 @@ func releaseBacklog(ctx context.Context, open *stores, by string) (*inventory.Pl
 	}
 	for _, p := range plans {
 		if p.Release != nil {
+			if by != "" && p.Release.Settings != nil {
+				return nil, fmt.Errorf("%s is sending %s; what waits is released once it ends — `plans %s` says where it is",
+					p.ID, p.Repository, p.ID)
+			}
 			if by != "" {
 				return nil, fmt.Errorf("%s is already releasing what waits; `plans %s` says where it is", p.ID, p.ID)
 			}
@@ -641,7 +645,9 @@ func releaseBacklog(ctx context.Context, open *stores, by string) (*inventory.Pl
 			return nil, err
 		}
 		for _, p := range recent {
-			if p.Release == nil {
+			// A settings walk that failed holds nothing back (novox/hq ADR 0344 §6): its failure is its module's
+			// settings on one machine, said on its own, not a build no gate passed.
+			if p.Release == nil || p.Release.Settings != nil {
 				continue
 			}
 			if p.State == inventory.PlanFailed {
@@ -702,6 +708,9 @@ func releaseBacklog(ctx context.Context, open *stores, by string) (*inventory.Pl
 // gate, or the machine being judged judged once more; the plan done when every machine is.
 func advanceRelease(ctx context.Context, open *stores, p *inventory.Plan) (bool, error) {
 	r := p.Release
+	if r.Settings != nil {
+		return advanceSettingsWalk(ctx, open, p)
+	}
 	now := time.Now().UTC()
 	if r.Gate == nil {
 		heard, err := releaseHeard(ctx, open)