Say when the lease is handed away, let the vault and the grants part read it, and let the grants part create the consumers an account needs, so both turn on at the lease write alone (issue 774, ADR 0561 §3, §6)

go/buscompose/accounts.go

@@ -186,3 +186,59 @@ func HeldCredential(w WantedAccount, password string) ([]byte, error) {
 	}{URL: w.URL, Fingerprint: w.Fingerprint, Node: w.Node, Module: w.Module, User: w.User, Password: password,
 		Claims: w.Claims})
 }
+
+// **One issuer at every moment: minting turns on at the lease write** (novox/hq ADR 0561 §3, §6). The controller's lease
+// is the one key `holder` of its bucket (LeaseBucket). The operator's credential hands it away by writing a value that
+// names its new holder in `handed-to`; while the key holds that, the vault mints and the grants part creates the durable
+// consumers an account needs. A controller's value, a key deleted or expired, or one that cannot be read or parsed, turn
+// both off: when in doubt nothing is minted, so the controller and the vault never both mint one account. No clock and
+// no setting turns it.
+
+// ControllerLease is the lease's bucket as a reader names it; the vault and the grants part alone read it
+// (NamedReaders), the controller's announcement marking it readable by nobody.
+const ControllerLease = ControllerSeat + ".lease"
+
+// ControllerLeaseKey is the lease's one key.
+const ControllerLeaseKey = leaseKey
+
+// LeaseHolder is the lease key's value: a controller instance's (mesh-controller internal/lease Holder), or, once handed
+// away, one naming its holder in HandedTo.
+type LeaseHolder struct {
+	Instance string    `json:"instance,omitempty"`
+	Host     string    `json:"host,omitempty"`
+	Epoch    uint64    `json:"epoch,omitempty"`
+	Taken    time.Time `json:"taken,omitzero"`
+	Renewed  time.Time `json:"renewed,omitzero"`
+	// HandedTo is who holds the lease once the controller handed it away: never a controller instance.
+	HandedTo string `json:"handed-to,omitempty"`
+	// HandedBy is the credential that wrote it (the operator's), and Why its reason.
+	HandedBy string `json:"handed-by,omitempty"`
+	Why      string `json:"why,omitempty"`
+}
+
+// LeaseHandedAway reads the lease key as a getter answered it (its value, whether it was there, the read's error) and
+// says whether it is handed to a holder that is no controller, with why either way.
+func LeaseHandedAway(raw []byte, found bool, readErr error) (bool, string) {
+	switch {
+	case readErr != nil:
+		return false, "the controller's lease cannot be read (" + readErr.Error() + "), so nothing is minted"
+	case !found || len(raw) == 0 || string(raw) == "null":
+		return false, "no lease is written (expired, deleted, or never taken): a controller may take it, so nothing is minted"
+	}
+	var h LeaseHolder
+	if err := json.Unmarshal(raw, &h); err != nil {
+		return false, "the controller's lease is not readable as a holder (" + err.Error() + "), so nothing is minted"
+	}
+	if strings.TrimSpace(h.HandedTo) == "" {
+		who := h.Instance
+		if who == "" {
+			who = "an instance that names itself not"
+		}
+		return false, "the controller holds the lease (" + who + "): it mints, so the vault mints nothing (ADR 0561 §3)"
+	}
+	if h.Instance != "" {
+		return false, "the lease names both a controller instance (" + h.Instance + ") and a holder it is handed to (" +
+			h.HandedTo + "), so nothing is minted"
+	}
+	return true, "the lease is handed to " + h.HandedTo + ": the vault mints every new account (ADR 0561 §1, §3)"
+}

go/buscompose/announced.go

@@ -1,6 +1,7 @@
 package buscompose
 
 import (
+	"slices"
 	"sort"
 	"strings"
 
@@ -58,6 +59,10 @@ func ReadsAnnouncedBy(reader string, reads []string, announced map[string]announ
 		switch {
 		case reader != "" && !ReaderMay(reader, r):
 			refused = append(refused, r)
+		case reader != "" && namedReader(reader, r):
+			// A state the composer names its readers for is theirs whatever its owner announced (ADR 0561 §3: the
+			// controller's lease, which its announcement marks readable by nobody).
+			granted = append(granted, r)
 		case reader != "" && ok && said && s.Keeps(name):
 			if s.ReadableBy(name, reader) {
 				granted = append(granted, r)
@@ -95,3 +100,8 @@ func NotAnnounced(r Records) []string {
 	sort.Strings(out)
 	return out
 }
+
+// namedReader says the composer names module among the readers of read (NamedReaders).
+func namedReader(module, read string) bool {
+	return slices.Contains(NamedReaders[strings.TrimSpace(read)], module)
+}

go/buscompose/buscompose_test.go

@@ -2,6 +2,11 @@ package buscompose
 
 import (
 	"encoding/json"
+	"errors"
+	"time"
+
+	"git.novox.be/novox/mesh-sdk/go/announce"
+	"github.com/nats-io/nats.go/jetstream"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -51,6 +56,13 @@ func mayBeyondTheControllers(user string) map[string]bool {
 		VaultSecretChanged: true}
 }
 
+// createsAnAccountsConsumer is the grants part's create and read of a durable consumer an account needs, by its stream
+// and name (novox/hq ADR 0561 §6): beyond the controller's on purpose, since the controller made them alone.
+func createsAnAccountsConsumer(user, g string) bool {
+	return strings.HasSuffix(user, "."+GrantsModule) &&
+		(strings.HasPrefix(g, "$JS.API.CONSUMER.CREATE.") || strings.HasPrefix(g, "$JS.API.CONSUMER.INFO."))
+}
+
 // quotedToken is a quoted token of a composed list.
 var quotedToken = regexp.MustCompile(`"[^"]*"`)
 
@@ -102,7 +114,8 @@ func grantsAsTheControllers(t *testing.T, got, want string) {
 			}
 		}
 		for g := range now {
-			if !was[g] && !intended[g] && !mayBeyondTheControllers(user)[g] && !createdAdvisory.MatchString(`"`+g+`", `) {
+			if !was[g] && !intended[g] && !mayBeyondTheControllers(user)[g] && !createdAdvisory.MatchString(`"`+g+`", `) &&
+				!createsAnAccountsConsumer(user, g) {
 				t.Errorf("%s: the copy grants %s beyond the controller's, and no decision names it", user, g)
 			}
 		}
@@ -397,4 +410,65 @@ func TestTheCopiedComposerComposesAsTheControllers(t *testing.T) {
 			t.Error("an account was held with no password")
 		}
 	})
+	// 774 subtasks 6 and 8 (novox/hq ADR 0561 §3, §6): minting and the grants part's consumers turn on only while the
+	// lease is handed to a holder that is no controller; the vault and the grants part alone read the lease, whatever the
+	// controller announced; a module's consumer is created as the controller's EnsureConsumer creates it.
+	t.Run("the lease turns minting on only when handed away; a consumer is created as the controller's", func(t *testing.T) {
+		for _, row := range []struct {
+			name  string
+			raw   string
+			found bool
+			err   error
+			on    bool
+		}{
+			{"a controller holds it", `{"instance":"novox/1234/2026-10-27T20:00:00Z","epoch":57}`, true, nil, false},
+			{"handed away", `{"handed-to":"the operator's hand-over","handed-by":"person.jochen"}`, true, nil, true},
+			{"expired or deleted", ``, false, nil, false},
+			{"unreadable", ``, false, errors.New("refused"), false},
+			{"not a holder", `[1]`, true, nil, false},
+			{"both a controller and a handed holder", `{"instance":"novox/1","handed-to":"x"}`, true, nil, false},
+		} {
+			if on, why := LeaseHandedAway([]byte(row.raw), row.found, row.err); on != row.on || why == "" {
+				t.Errorf("%s: on %v (%s), want %v", row.name, on, why, row.on)
+			}
+		}
+		announced := map[string]announce.States{ControllerSeat: ControllerAnnouncement("novox")}
+		for reader, want := range map[string]bool{VaultSeat: true, GrantsModule: true, "mesh-delivery-view": false} {
+			granted, _ := ReadsAnnouncedBy(reader, []string{ControllerLease}, announced)
+			if (len(granted) == 1) != want {
+				t.Errorf("%s reads the lease: %v, want %v", reader, granted, want)
+			}
+		}
+		c, _ := ConsumerFor(Principal{Kind: KindModule, Node: "a", Module: "m", Consumes: []string{"x.happened"}})
+		cfg := ConsumerConfig(c)
+		if cfg.Durable != "a_m" || cfg.AckPolicy != jetstream.AckExplicitPolicy || cfg.AckWait != 30*time.Second ||
+			cfg.MaxDeliver != 5 || cfg.DeliverPolicy != jetstream.DeliverNewPolicy || len(cfg.FilterSubjects) != 2 ||
+			cfg.Description == "" {
+			t.Errorf("a module's consumer is created as %+v", cfg)
+		}
+		// The grants part is granted the create of each account's consumer by its stream and name, and no other.
+		users, err := Users(Records{Nodes: []string{"a"}, Assigned: map[string][]Declared{"a": {
+			{Module: GrantsModule}, {Module: "m", Consumes: []string{"x.happened"}}, {Module: "quiet"}}}})
+		if err != nil {
+			t.Fatal(err)
+		}
+		for _, u := range users {
+			if u.Module != GrantsModule || u.Kind != KindModule {
+				continue
+			}
+			perms, err := PermissionsFor(u)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if !MayPublish(perms, "$JS.API.CONSUMER.CREATE.EVENTS.a_m") || MayPublish(perms, "$JS.API.CONSUMER.CREATE.EVENTS.a_quiet") ||
+				MayPublish(perms, "$JS.API.CONSUMER.DELETE.EVENTS.a_m") || MayPublish(perms, "$JS.API.CONSUMER.CREATE.EVENTS.a_m.mesh.mod.x.event.happened") {
+				t.Errorf("the grants part creates consumers as %v", u.CreatesConsumers)
+			}
+		}
+		q := ConsumerConfig(QueueConsumer(Principal{Kind: KindProcess, Node: "a", Module: "m", Process: "p"},
+			QueueOwner{Process: "p", Stream: "M_WORK", MaxDeliver: 3}))
+		if q.Durable != "a_m_p" || q.FilterSubject != "" || q.MaxDeliver != 3 || q.DeliverPolicy != jetstream.DeliverAllPolicy {
+			t.Errorf("a process's queue consumer is created as %+v", q)
+		}
+	})
 }

go/buscompose/create.go

@@ -86,3 +86,30 @@ func ModuleStreamConfig(m ModuleStream) jetstream.StreamConfig {
 	}
 	return cfg
 }
+
+// ConsumerConfig is a pull consumer as the controller's EnsureConsumer creates it (mesh-controller internal/broker
+// JetStream.EnsureConsumer, a consumer not there yet): its durable name, explicit acks, its ack wait, max deliver and max
+// ack pending, its description, one filter or several, and from the stream's end when it is made FromNow. The grants part
+// creates a module's and a process's consumers with it from the lease write (novox/hq ADR 0561 §6): a create alone,
+// never an update of one the bus holds. A push consumer or a queue group is the controller's own and never made here.
+func ConsumerConfig(c Consumer) jetstream.ConsumerConfig {
+	cfg := jetstream.ConsumerConfig{
+		Durable:       c.Name,
+		AckPolicy:     jetstream.AckExplicitPolicy,
+		AckWait:       time.Duration(c.AckWaitSeconds) * time.Second,
+		MaxDeliver:    c.MaxDeliver,
+		MaxAckPending: c.MaxAckPending,
+		Description:   c.Why,
+	}
+	switch len(c.Filters) {
+	case 0:
+	case 1:
+		cfg.FilterSubject = c.Filters[0]
+	default:
+		cfg.FilterSubjects = c.Filters
+	}
+	if c.FromNow {
+		cfg.DeliverPolicy = jetstream.DeliverNewPolicy
+	}
+	return cfg
+}

go/buscompose/derived.go

@@ -247,6 +247,30 @@ func ConsumersOf(users []Principal) []ModuleConsumer {
 	return out
 }
 
+// AccountConsumers are the durable consumers an account needs (novox/hq ADR 0561 §6): of ConsumersOf, each module's on
+// EVENTS and each process's on its own work queue, never one on a module stream it hears (those the controller makes with
+// the stream's grant). The grants part creates them from the lease write, with these configurations.
+func AccountConsumers(users []Principal) []ModuleConsumer {
+	queues := map[string]bool{}
+	for _, p := range users {
+		for _, q := range p.Queues {
+			queues[q.Stream] = true
+		}
+		for _, d := range p.Carries {
+			for _, q := range d.Queues {
+				queues[q.Stream] = true
+			}
+		}
+	}
+	var out []ModuleConsumer
+	for _, mc := range ConsumersOf(users) {
+		if mc.Consumer.Stream == consumerStream(Principal{Kind: KindModule}) || queues[mc.Consumer.Stream] {
+			out = append(out, mc)
+		}
+	}
+	return out
+}
+
 // HolderConsumerFor is the worker a seat's holders share on that seat's work queue.
 //
 // **One worker for every holder, and each holder pulls one ask when it is idle** (novox/hq ADR

go/buscompose/nats.go

@@ -232,6 +232,10 @@ type Principal struct {
 	// by name. Created only, never updated or deleted: a new module state is on the bus when the grants part hears its
 	// manifest, not at the controller's next start (issue 1790).
 	CreatesStreams []string
+	// CreatesConsumers are the durable consumers the grants part's principal alone may create beside the controller
+	// (novox/hq ADR 0561 §6): each placed module's on EVENTS and each process's on its work queue (AccountConsumers), by
+	// stream and name. Created only, never updated or deleted.
+	CreatesConsumers []ModuleConsumer
 
 	// PasswordHash is the bcrypt hash the mesh minted. The plaintext is sealed to the principal
 	// and never appears here: this file is written to a node's disk and read by a server, and a
@@ -972,6 +976,8 @@ func PermissionsFor(p Principal) (Permissions, error) {
 			// And creating each stream a manifest declares, by its own name (the operator, 2026-10-26 08:54; issue
 			// 1790): the create and the read of that one stream, never an update, a delete or a stream not declared.
 			pub = append(pub, CreateStreamGrants(p.CreatesStreams)...)
+			// And creating each durable consumer an account needs, by its stream and name (ADR 0561 §6).
+			pub = append(pub, CreateConsumerGrants(p.CreatesConsumers)...)
 			// And its own object bucket, where it writes the user list sealed to the bus node (ADR 0547 clause 7).
 			pub = append(pub, GrantsUserListWrites()...)
 		}
@@ -1659,6 +1665,21 @@ func CreateStreamGrants(streams []string) []string {
 	return out
 }
 
+// CreateConsumerGrants are the subjects that create each consumer by its stream and name, and read its info back: the
+// create of the client library's CreateConsumer for a consumer with no filter or several, never one filter's form (a
+// wildcard in a filter would widen the grant), an update or a delete.
+func CreateConsumerGrants(consumers []ModuleConsumer) []string {
+	var out []string
+	for _, mc := range consumers {
+		c := mc.Consumer
+		if !safeSubject.MatchString(c.Stream) || !safeSubject.MatchString(c.Name) || len(c.Filters) == 1 {
+			continue
+		}
+		out = append(out, "$JS.API.CONSUMER.CREATE."+c.Stream+"."+c.Name, "$JS.API.CONSUMER.INFO."+c.Stream+"."+c.Name)
+	}
+	return out
+}
+
 // GrantsModule is the one module whose principal publishes the modules' memberships (novox/hq ADR 0547 §5): the grants
 // part, which composes them from the manifests and placement. It defines no stream and is granted no other subject here.
 const GrantsModule = "mesh-grants"

go/buscompose/userlist_switch.go

@@ -79,7 +79,9 @@ const VaultBusAccounts = "mesh-vault.bus-accounts"
 
 // NamedReaders are the states only the modules named may read, by `<owner>.<name>`: the grants part's wanted accounts
 // are read by the vault alone (novox/hq ADR 0561 §2).
-var NamedReaders = map[string][]string{VaultBusAccounts: {GrantsModule}, GrantsAccounts: {VaultSeat}}
+// The controller's lease is read by the two parts that turn on at its write (ADR 0561 §3, §6).
+var NamedReaders = map[string][]string{VaultBusAccounts: {GrantsModule}, GrantsAccounts: {VaultSeat},
+	ControllerLease: {VaultSeat, GrantsModule}}
 
 // ReaderMay says whether module may read the state read (`<owner>.<name>`) by the named readers: always, for a state
 // that names none.

go/buscompose/users.go

@@ -149,6 +149,7 @@ func Users(r Records) ([]Principal, error) {
 		AsksTheConfig: servedOf(r, VerbsTheControllerAsksTheConfig), FilesFor: sortedCopy(r.Nodes)}}
 
 	served := servedReadsOf(r)
+	grants := -1
 	for _, node := range sortedCopy(r.Nodes) {
 		witness := false
 		var checks []string
@@ -225,6 +226,7 @@ func Users(r Records) ([]Principal, error) {
 			// 08:54): every placed module's buckets, logs and streams, each by its stream's name.
 			if d.Module == GrantsModule {
 				out[len(out)-1].CreatesStreams = declaredStreamsOf(r)
+				grants = len(out) - 1
 			}
 			// **The vault's holder asks the desks and the issuing providers itself** (issue 723), under the
 			// account its own runtime runs on (ADR 0259 §8's runs-as): the one module granted it.
@@ -258,6 +260,11 @@ func Users(r Records) ([]Principal, error) {
 		out = append(out, p)
 	}
 
+	// The grants part creates the durable consumers the accounts need (novox/hq ADR 0561 §6), by stream and name.
+	if grants >= 0 {
+		out[grants].CreatesConsumers = AccountConsumers(out)
+	}
+
 	// Refused here rather than discovered by the server. Two users with one name is a file the
 	// server reads as one of them, and which one depends on the order — so a module assigned to a
 	// node twice, or a person named after nothing, is a composition that must not be written.