Node shadow: reuse a running seal only at its own slot, lay values as the controller does, answer the newest candidate first and say how it goes (issue 1126, C1 C2, T1 T2 T3)

A box is reused by slot (resource, field) after the composition, from what runs or the
have's slots; a have written before slots is reused within its module alone. Config
values are laid by mesh-sdk's one rule (never a default). The shadow answers the
newest candidate first and hands each answer as it lands, says when an answer starts,
every minute what it waits on, and when it ends, and fits an answer to the node's key.
Needs mesh-sdk fix/1126-seed-same (16b8d8a1).

cmd/mesh-host/nodeagent.go

@@ -62,14 +62,14 @@ func (h sessionHaves) Read(ctx context.Context, module string) (agent.Have, bool
 		if !ok || got.Composed == "" {
 			return agent.Have{}, false
 		}
-		return agent.Have{Module: module, Composed: got.Composed, Sealed: got.Sealed}, true
+		return agent.Have{Module: module, Composed: got.Composed, Sealed: got.SealedAt}, true
 	}
 	got, ok := h.session.ReadHave(ctx, module)
 	if !ok {
 		return agent.Have{}, false
 	}
 	return agent.Have{Module: module, FP: got.FP, Composed: got.Composed, Phase: string(got.Phase), Detail: got.Detail,
-		Sealed: got.Sealed}, true
+		Sealed: got.SealedAt}, true
 }
 
 // ReadErr is Read telling a have absent from one the bus could not read (agent.HavesReadErr).
@@ -83,7 +83,7 @@ func (h sessionHaves) ReadErr(ctx context.Context, module string) (agent.Have, b
 		return agent.Have{}, false, err
 	}
 	return agent.Have{Module: module, FP: got.FP, Composed: got.Composed, Phase: string(got.Phase), Detail: got.Detail,
-		Sealed: got.Sealed}, true, nil
+		Sealed: got.SealedAt}, true, nil
 }
 
 func (h sessionHaves) Write(ctx context.Context, x agent.Have) {
@@ -535,16 +535,16 @@ func nodeAgent(ctx context.Context, opts options, signer ed25519.PublicKey, sess
 			},
 			unseal: sealOpener(opts.state),
 			// And what each module's have says it runs sealed: after a restart the agent has applied nothing yet.
-			held: func(module string) []string {
+			held: func(module string) (delivery.Seals, []string) {
 				if module == agent.NodeModule {
 					got, _ := session.ReadNodeHave(linked)
-					return got.Sealed
+					return got.SealedAt, got.Sealed
 				}
 				got, ok := session.ReadHave(linked, module)
 				if !ok {
-					return nil
+					return nil, nil
 				}
-				return got.Sealed
+				return got.SealedAt, got.Sealed
 			},
 			refused: func(why string) {
 				if now := own.get(); now != nil && run.Err() == nil {
@@ -870,7 +870,7 @@ type composerHooks struct {
 	running func() []delivery.Composed
 	unseal  func(string) ([]byte, error)
 	refused func(string)
-	held    func(module string) []string
+	held    func(module string) (delivery.Seals, []string)
 }
 
 func selfComposer(ctx context.Context, session *link.Session, node string, say func(string), hooks composerHooks) (*selfcompose.Composer, string) {