Merge main (delivery 1, the parse-only sdk) into L3's re-land, and pin mesh-sdk 2da0de7, the release's final head (issue 774)

The conflicts were go.mod, go.sum and testdata/beside/CAPTURED alone, taken from the release. 2da0de7 is 6e4a301's code;
its conformance events are unchanged.

cmd/mesh-host/applied_store.go

@@ -0,0 +1,107 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+)
+
+// appliedStore keeps every composition the agent applied, one file per module (the node's own as `node.json`), in the
+// directory `applied` beside the node's state (agent.Env.Applied, issue 774). It is the machine's own record of what runs:
+// read at the agent's start before anything is watched, so the node never composes its own as if a module it runs ran
+// nothing because the bucket no longer keeps that composition or the kept declaration is retired. Files are 0600 in a
+// 0700 directory: a composition carries values sealed to this machine.
+type appliedStore struct{ dir string }
+
+func appliedStoreFor(statePath string) appliedStore {
+	return appliedStore{dir: filepath.Join(filepath.Dir(statePath), "applied")}
+}
+
+// appliedName is a module name the store takes as a file name: a catalogue module's or the node's own, never a path.
+var appliedName = regexp.MustCompile(`^[a-z0-9][a-z0-9._-]*$`)
+
+func (s appliedStore) path(module string) (string, error) {
+	if !appliedName.MatchString(module) || strings.Contains(module, "..") {
+		return "", fmt.Errorf("%q is not a module name the applied store takes", module)
+	}
+	return filepath.Join(s.dir, module+".json"), nil
+}
+
+// holds says whether the store keeps the module's composition.
+func (s appliedStore) holds(module string) bool {
+	path, err := s.path(module)
+	if err != nil {
+		return false
+	}
+	_, err = os.Stat(path)
+	return err == nil
+}
+
+func (s appliedStore) Load() (map[string][]byte, error) {
+	entries, err := os.ReadDir(s.dir)
+	if errors.Is(err, os.ErrNotExist) {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+	out := map[string][]byte{}
+	var errs []error
+	for _, e := range entries {
+		module, ok := strings.CutSuffix(e.Name(), ".json")
+		if !ok || e.IsDir() || !appliedName.MatchString(module) {
+			continue
+		}
+		raw, err := os.ReadFile(filepath.Join(s.dir, e.Name()))
+		if err != nil {
+			errs = append(errs, err)
+			continue
+		}
+		out[module] = raw
+	}
+	return out, errors.Join(errs...)
+}
+
+func (s appliedStore) Keep(module string, raw []byte) error {
+	path, err := s.path(module)
+	if err != nil {
+		return err
+	}
+	if was, err := os.ReadFile(path); err == nil && string(was) == string(raw) {
+		return nil
+	}
+	if err := os.MkdirAll(s.dir, 0o700); err != nil {
+		return err
+	}
+	tmp, err := os.CreateTemp(s.dir, "."+module+".*")
+	if err != nil {
+		return err
+	}
+	defer os.Remove(tmp.Name())
+	if _, err := tmp.Write(raw); err != nil {
+		tmp.Close()
+		return err
+	}
+	if err := tmp.Sync(); err != nil {
+		tmp.Close()
+		return err
+	}
+	if err := tmp.Close(); err != nil {
+		return err
+	}
+	return os.Rename(tmp.Name(), path)
+}
+
+func (s appliedStore) Drop(module string) error {
+	path, err := s.path(module)
+	if err != nil {
+		return err
+	}
+	if err := os.Remove(path); err != nil && !errors.Is(err, os.ErrNotExist) {
+		return err
+	}
+	return nil
+}

cmd/mesh-host/authority_test.go

@@ -1,16 +1,27 @@
 package main
 
 import (
+	"context"
+	"crypto/ed25519"
+	"crypto/x509"
+	"encoding/base64"
 	"encoding/json"
+	"encoding/pem"
 	"os"
 	"path/filepath"
 	"testing"
+	"time"
 
+	"git.novox.be/novox/mesh-sdk/go/buscompose"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/overlay"
+
+	"github.com/novox/mesh-host/internal/identity"
 )
 
 // Issue 1126 (ADR 0555 §3): the mesh's own certificate a composition carries is kept for the machine's record, and the
-// record's keys read it; a composition carrying none changes nothing.
+// record's keys read it; a composition carrying none changes nothing. And (L3 s6, s7; ADR 0550 §2) the record says what
+// the node trusts a mesh signature from, and the node keeps the certificate the vault signed for it.
 func TestTheAppliedAuthorityIsKeptForTheRecord(t *testing.T) {
 	state := filepath.Join(t.TempDir(), "state", "state.json")
 	res := func(id, content string) json.RawMessage {
@@ -26,7 +37,137 @@ func TestTheAppliedAuthorityIsKeptForTheRecord(t *testing.T) {
 	if err := keepAuthority(state, delivery.Composed{Resources: []json.RawMessage{res("ca-trust.certificate-authority", "CA-1")}}); err != nil {
 		t.Fatal(err)
 	}
-	if got := recordKeys(state)(); got.Authority != "CA-1" {
+	if got := recordKeys(state, nil)(); got.Authority != "CA-1" {
 		t.Errorf("the record's keys read the authority %q", got.Authority)
 	}
+
+	// L3 s6: before the vault's signers are read the node trusts the controller's key alone; once read, a message the
+	// vault signed is accepted and the record names both; once the lease is handed away the controller's key is refused
+	// and the record names the vault's alone. Each change tells the record's writer.
+	controllerPub, controller, _ := ed25519.GenerateKey(nil)
+	vaultPub, vault, _ := ed25519.GenerateKey(nil)
+	trust := newMeshTrust(controllerPub)
+	told := 0
+	trust.onChange(func() { told++ })
+	keys := recordKeys(state, trust.Trusts)
+	ctrlFP, vaultFP := delivery.SignerFingerprint(controllerPub), delivery.SignerFingerprint(vaultPub)
+	if got := keys().Trusts; !delivery.TrustsKey(got, delivery.SignerController, ctrlFP) || delivery.TrustsKey(got, delivery.SignerVault, vaultFP) {
+		t.Errorf("before the signers are read the record trusts %v", got)
+	}
+	enrol, _ := delivery.SignContext(delivery.KindEnrolment)
+	msg := []byte("a reply")
+	if _, err := trust.Verify(delivery.KindEnrolment, msg, delivery.SignMessage(vault, enrol, msg)); err == nil {
+		t.Error("a vault-signed message is accepted before the vault's key is read")
+	}
+	vaultCA := testAuthority(t, vaultPub, vault)
+	keyValue, _ := json.Marshal(delivery.NewSignerKey(vaultPub, time.Now()))
+	fp, _ := delivery.AuthorityFingerprint(vaultCA)
+	authValue, _ := json.Marshal(delivery.SignerAuthority{Certificate: vaultCA, Fingerprint: fp, Made: time.Now()})
+	trust.heardSigner(delivery.SignersKeyKey, keyValue, false, func(string) {})
+	trust.heardSigner(delivery.SignersAuthorityKey, authValue, false, func(string) {})
+	if s, err := trust.Verify(delivery.KindEnrolment, msg, delivery.SignMessage(vault, enrol, msg)); err != nil || s.Name != delivery.SignerVault {
+		t.Errorf("a vault-signed message on a node that read signers: %+v, %v", s, err)
+	}
+	if got := keys().Trusts; !delivery.TrustsKey(got, delivery.SignerController, ctrlFP) || !delivery.TrustsKey(got, delivery.SignerVault, vaultFP) ||
+		trust.VaultAuthority() != vaultCA || told != 2 {
+		t.Errorf("after the signers are read the record trusts %v (told %d)", got, told)
+	}
+	handed, _ := json.Marshal(buscompose.LeaseHolder{HandedTo: "mesh-vault", HandedBy: "person.operator"})
+	trust.heardLease(handed, true, nil)
+	if _, err := trust.Verify(delivery.KindEnrolment, msg, delivery.SignMessage(controller, enrol, msg)); err == nil || trust.Controller() != nil {
+		t.Error("after the lease is handed away the controller's key is still trusted")
+	}
+	if got := keys().Trusts; delivery.TrustsKey(got, delivery.SignerController, ctrlFP) || !delivery.TrustsKey(got, delivery.SignerVault, vaultFP) || told != 3 {
+		t.Errorf("after the lease is handed away the record trusts %v (told %d)", got, told)
+	}
+	trust.heardLease(handed, true, nil)
+	if told != 3 {
+		t.Error("a lease heard again unchanged wrote the record again")
+	}
+	// A signers' key naming another fingerprint is not trusted.
+	bad, _ := json.Marshal(delivery.SignerKey{Key: base64.StdEncoding.EncodeToString(controllerPub), Fingerprint: vaultFP})
+	trust.heardSigner(delivery.SignersKeyKey, bad, false, func(string) {})
+	if !delivery.TrustsKey(keys().Trusts, delivery.SignerVault, vaultFP) {
+		t.Error("a signers' key that does not check replaced the vault's")
+	}
+
+	// L3 s7: the certificate the vault signs for this node's internal name and serving key is kept where the record reads
+	// it, and the record is written again; one signed by another authority is refused and nothing is kept.
+	serving, err := identity.GenerateServingKey()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := identity.WriteServingKey(identity.ServingKeyPath(state), serving); err != nil {
+		t.Fatal(err)
+	}
+	servingPub, _ := base64.StdEncoding.DecodeString(serving.Public)
+	signedBy := func(ca string, key ed25519.PrivateKey) string {
+		parent, _ := delivery.ParseCertificate(ca)
+		der, err := x509.CreateCertificate(nil, delivery.NodeCertificateTemplate(overlay.InternalName("n1"), servingPub, time.Now().Add(-time.Hour)),
+			parent, ed25519.PublicKey(servingPub), key)
+		if err != nil {
+			t.Fatal(err)
+		}
+		return string(pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: der}))
+	}
+	var asked []any
+	answer := signedBy(vaultCA, vault)
+	ask := func(_ context.Context, verb string, args any) (json.RawMessage, error) {
+		asked = append(asked, verb, args)
+		return json.Marshal(delivery.SignAnswer{Kind: delivery.KindNodeCertificate, Node: "n1", Certificate: answer})
+	}
+	written := 0
+	if err := certifyThisNode(context.Background(), state, "n1", trust, ask, func() { written++ }); err != nil {
+		t.Fatal(err)
+	}
+	if got := recordKeys(state, nil)(); got.Certificate != answer || written != 1 || len(asked) != 2 || asked[0] != delivery.SignVerb {
+		t.Errorf("the vault's certificate: kept %v, written %d, asked %v", got.Certificate == answer, written, asked)
+	}
+	answer = signedBy(testAuthority(t, controllerPub, controller), controller)
+	if err := certifyThisNode(context.Background(), state, "n1", trust, ask, func() { written++ }); err == nil || written != 1 {
+		t.Errorf("a certificate of another authority was kept: %v", err)
+	}
+
+	// Issue 774: what the engine applied is kept beside the state too, one file per module, 0600 in a 0700 directory,
+	// written by a rename so a crash leaves the one before; a name that is no module's is refused, never a path.
+	t.Run("the compositions the engine applied are kept beside the state", func(t *testing.T) {
+		applied := appliedStoreFor(filepath.Join(t.TempDir(), "state", "state.json"))
+		if m, err := applied.Load(); err != nil || len(m) != 0 || applied.holds("node") {
+			t.Fatalf("an empty store loads %v, %v", m, err)
+		}
+		for _, tc := range []struct {
+			module string
+			takes  bool
+		}{{"node", true}, {"nats", true}, {"mesh-delivery-view", true}, {"../state", false}, {"a/b", false}, {"..", false}, {"", false}} {
+			if err := applied.Keep(tc.module, []byte(`{"v":1}`)); (err == nil) != tc.takes {
+				t.Errorf("keeping %q: %v, want taken %v", tc.module, err, tc.takes)
+			}
+		}
+		if err := applied.Keep("node", []byte(`{"v":2}`)); err != nil {
+			t.Fatal(err)
+		}
+		entries, _ := os.ReadDir(applied.dir)
+		dirInfo, _ := os.Stat(applied.dir)
+		fileInfo, _ := os.Stat(filepath.Join(applied.dir, "node.json"))
+		if len(entries) != 3 || dirInfo.Mode().Perm() != 0o700 || fileInfo.Mode().Perm() != 0o600 {
+			t.Fatalf("the store holds %d files (want 3, no temporary one left), directory %v, file %v", len(entries), dirInfo.Mode(), fileInfo.Mode())
+		}
+		if err := applied.Drop("nats"); err != nil || applied.Drop("nats") != nil || applied.holds("nats") {
+			t.Fatalf("a dropped module is still held, or dropping twice fails: %v", err)
+		}
+		if m, err := applied.Load(); err != nil || string(m["node"]) != `{"v":2}` || len(m) != 2 {
+			t.Fatalf("the store loads %v, %v", m, err)
+		}
+	})
+}
+
+// testAuthority is a self-signed authority certificate for key, as the vault makes its own.
+func testAuthority(t *testing.T, pub ed25519.PublicKey, key ed25519.PrivateKey) string {
+	t.Helper()
+	tpl := delivery.AuthorityTemplate(pub, time.Now().Add(-time.Hour))
+	der, err := x509.CreateCertificate(nil, tpl, tpl, pub, key)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return string(pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: der}))
 }

cmd/mesh-host/engineseat.go

@@ -0,0 +1,277 @@
+package main
+
+import (
+	"bufio"
+	"context"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync/atomic"
+	"syscall"
+	"time"
+
+	stdio "git.novox.be/novox/mesh-sdk/go"
+	meshasker "git.novox.be/novox/mesh-sdk/go/asker"
+	"git.novox.be/novox/mesh-sdk/go/asks"
+	"github.com/novox/mesh-host/internal/accounts"
+	"github.com/novox/mesh-host/internal/apply"
+	"github.com/novox/mesh-host/internal/link"
+	"github.com/novox/mesh-host/internal/store"
+)
+
+// The node seat node-engine's judgements on this machine (novox/hq ADR 0563): what a hand-over and a library's take
+// would set and what the disk holds now, and whether this machine is root-free.
+
+// diskOf is what is on disk at a directory, as an act compares it when the operator's yes arrives: its owner and
+// group, its mode, and which file it is.
+func diskOf(info os.FileInfo) string {
+	owner := "unknown"
+	if uid, gid, ok := apply.OwnerOf(info); ok {
+		owner = fmt.Sprintf("%d:%d", uid, gid)
+	}
+	which := ""
+	if st, ok := info.Sys().(*syscall.Stat_t); ok {
+		which = fmt.Sprintf(" %v:%v", st.Dev, st.Ino)
+	}
+	return fmt.Sprintf("%s %o%s", owner, info.Mode().Perm(), which)
+}
+
+// handOverJudgeFrom judges a hand-over through the node seat as the controller's ask is judged (judgeFound): the
+// declared owner and mode it will set, and the disk as it is.
+func handOverJudgeFrom(statePath string) func(string) (link.Judged, error) {
+	return func(path string) (link.Judged, error) {
+		found, info, err := judgeFound(statePath, path)
+		if err != nil {
+			return link.Judged{}, err
+		}
+		return link.Judged{Subject: path, Path: path, Sets: orUnsaid(found.Declared), Disk: diskOf(info),
+			Words: "A directory of " + moduleOf(found.ID) + " is used as found: the mesh left its owner and mode."}, nil
+	}
+}
+
+func moduleOf(id string) string {
+	if at := strings.LastIndex(id, "."); at > 0 {
+		return id[:at]
+	}
+	return id
+}
+
+// accessJudgeFrom judges the take act on a library through the node seat (ADR 0328 §7, ADR 0563 §4): declared on this
+// machine, its home, and its root holding data the mesh has not taken; what the take sets, and the disk as it is.
+func accessJudgeFrom(statePath string) func(string, string) (link.Judged, error) {
+	return func(act, access string) (link.Judged, error) {
+		d, err := declaredNow(statePath, nil)
+		if errors.Is(err, store.ErrNothingDeclared) {
+			return link.Judged{}, errors.New("this node keeps no declaration, so it is declared no library")
+		}
+		if err != nil {
+			return link.Judged{}, fmt.Errorf("what runs on this node does not read: %w", err)
+		}
+		for _, l := range d.Libraries {
+			if apply.LibraryAccess(l.Library) != access {
+				continue
+			}
+			if !l.Home {
+				return link.Judged{}, fmt.Errorf("this machine is not the home of the library %s, and a library is "+
+					"taken on its home", l.Library)
+			}
+			ctx, cancel := context.WithTimeout(context.Background(), lookBound)
+			defer cancel()
+			if v := apply.JudgeLibrary(ctx, l); v.Kind != apply.VerdictWaitKeep {
+				return link.Judged{}, fmt.Errorf("the library %s does not wait for the operator's word to be kept "+
+					"(it is judged %s), so there is nothing to take", l.Library, v.Kind)
+			}
+			info, err := os.Lstat(l.Root)
+			if err != nil {
+				return link.Judged{}, fmt.Errorf("the library %s's root cannot be read: %v", l.Library, err)
+			}
+			return link.Judged{Subject: access, Path: filepath.Clean(l.Root),
+				Sets: "the group " + l.Group + ", group write and setgid on everything under its root",
+				Disk: diskOf(info), Words: "The library " + l.Library + " holds data the mesh has not taken."}, nil
+		}
+		return link.Judged{}, fmt.Errorf("the access %s names no library declared on this machine", access)
+	}
+}
+
+// askTakes asks the take of every library the look found waiting for the operator's word, once per library (ADR 0563
+// §4): asked by the engine itself, never a second time while one is open or after one was asked; access-act asks again
+// by hand.
+func askTakes(acts *link.HandActs, waiting []string, say func(string)) {
+	if acts == nil {
+		return
+	}
+	for _, access := range waiting {
+		if acts.AskedFor(link.ActAccess, access) {
+			continue
+		}
+		if _, err := acts.AskAccess(link.EngineSeat+"-"+acts.Node, link.ActTake, access,
+			"its root holds data outside its group", true); err != nil && say != nil {
+			say("the take of " + access + " could not be asked: " + err.Error())
+		}
+	}
+}
+
+// lastAccounts is the newest look at every account (the health loop's), which root-free judges from.
+var lastAccounts atomic.Pointer[accounts.Statement]
+
+// rootFreshFor is how old the verdict root-free judges from may be (ADR 0563 §6, the controller's verdictFreshFor).
+const rootFreshFor = 15 * time.Minute
+
+// judgeRootFree is this machine's root-free (ADR 0259 §8, ADR 0563 §6): free only on the engine's own verdict, at most
+// rootFreshFor old, that every account declared never to become root without a person cannot, at least one such
+// account declared, and the login shell's execute not served here. Anything else is no pass, and says why.
+func judgeRootFree(node string, st *accounts.Statement, now time.Time, served bool, servedWhy string) link.RootVerdict {
+	v := link.RootVerdict{Machine: node, Judged: now.UTC()}
+	var not []string
+	confined := ""
+	switch {
+	case st == nil:
+		not = append(not, "this machine's engine has judged no account yet")
+	case now.Sub(st.At) > rootFreshFor:
+		not = append(not, fmt.Sprintf("the engine's newest judgement of its accounts was made at %s, more than %d "+
+			"minutes ago, and a verdict that old is not a verdict on now", st.At.UTC().Format(time.RFC3339),
+			int(rootFreshFor.Minutes())))
+	default:
+		var named []string
+		for _, a := range st.Accounts {
+			if !a.Root {
+				continue
+			}
+			named = append(named, a.Name)
+			if a.State != accounts.Healthy {
+				not = append(not, "the account "+a.Name+" "+orNoneKnownWord(a.Reason))
+			}
+		}
+		if len(named) == 0 {
+			not = append(not, "no account here is declared never to become root, so agents run as the operator's "+
+				"account, which may become root")
+		} else if len(not) == 0 {
+			confined = "the account " + strings.Join(named, ", ") + " cannot become root without a person (judged " +
+				st.At.UTC().Format(time.RFC3339) + ")"
+		}
+	}
+	if served {
+		not = append(not, "the login shell runs any command an agent gives it as the machine's runtime account, which "+
+			"can become root ("+servedWhy+")")
+	}
+	if len(not) > 0 {
+		v.Why = strings.Join(not, "; ")
+		return v
+	}
+	v.Free, v.Why = true, confined+"; the login shell's execute is not served here"
+	return v
+}
+
+func orNoneKnownWord(s string) string {
+	if s == "" {
+		return "is not judged"
+	}
+	return s
+}
+
+// settingFileSuffix is the resource the login shell's holder renders its setting execute into (ADR 0268: zsh's
+// tools-conf, `execute=serve` or `execute=withhold`), read beside the bus's discovery.
+const settingFileSuffix = ".tools-conf"
+
+// executeServedHere is whether the login shell's execute is served on this machine (ADR 0268), failing closed: served
+// while the bus's discovery hears it answered here or could not be asked, or while the holder's setting file applied
+// here says anything but withhold or cannot be read. why says which.
+func executeServedHere(statePath string, heard func() (bool, error)) (bool, string) {
+	var why []string
+	if heard == nil {
+		why = append(why, "the bus could not be asked whether execute is answered here")
+	} else if h, err := heard(); err != nil {
+		why = append(why, "the bus could not be asked whether execute is answered here: "+err.Error())
+	} else if h {
+		why = append(why, "the bus hears execute answered here")
+	}
+	known, err := store.Load(statePath)
+	if err != nil {
+		why = append(why, "what this machine applied could not be read: "+err.Error())
+	}
+	for _, r := range known.Resources {
+		if r.Type != "file" || !strings.HasSuffix(r.ID, settingFileSuffix) {
+			continue
+		}
+		if value, err := settingIn(r.Target); err != nil {
+			why = append(why, moduleOf(r.ID)+"'s setting execute cannot be read: "+err.Error())
+		} else if value != "withhold" {
+			why = append(why, moduleOf(r.ID)+"'s setting execute here is "+value)
+		}
+	}
+	return len(why) > 0, strings.Join(why, "; ")
+}
+
+// settingIn is the value of execute in a setting file, "" when it says none.
+func settingIn(path string) (string, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+	value := ""
+	lines := bufio.NewScanner(f)
+	for lines.Scan() {
+		t := strings.TrimSpace(lines.Text())
+		if key, v, ok := strings.Cut(t, "="); ok && !strings.HasPrefix(t, "#") && strings.TrimSpace(key) == "execute" {
+			value = strings.TrimSpace(v)
+		}
+	}
+	if value == "" {
+		value = "not said"
+	}
+	return value, lines.Err()
+}
+
+// keepWaiting is every library a look found waiting for the operator's word to keep it (ADR 0328 §8).
+func keepWaiting(vs []link.ResourceHealth) []string {
+	var out []string
+	for _, v := range vs {
+		for _, w := range v.AccessWaits {
+			if w.Reason == link.WaitKeep {
+				out = append(out, w.Access)
+			}
+		}
+	}
+	return out
+}
+
+// engineActs is the node seat this engine holds (ADR 0563): judged and performed by the same code as the controller's
+// signed asks, its asks to the operator over the session's link, its acts kept beside the state.
+func engineActs(opts options, node string, queue *link.Session, search *accounts.SetuidCache) *link.HandActs {
+	state := link.BusState{Session: queue, Node: node}
+	h := &link.HandActs{Node: node, State: state,
+		JudgeHandOver: handOverJudgeFrom(opts.state), HandOver: handOverFrom(opts.state),
+		JudgeAccess: accessJudgeFrom(opts.state), AccessAct: accessActFrom(opts.state, opts.timeout),
+		JudgeDirectories: judgeDirectoriesFrom(opts.state), SetuidSearch: queue.SetuidSearch, Searching: search.Running,
+		RootFree: func() link.RootVerdict {
+			served, why := executeServedHere(opts.state, func() (bool, error) {
+				return queue.HeardServed("node-login-shell", "execute")
+			})
+			return judgeRootFree(node, lastAccounts.Load(), time.Now(), served, why)
+		},
+		Say: queue.SayEngine}
+	asker := asks.EngineAsker(node)
+	h.Asker = &meshasker.Client{Module: asker, State: state, Publish: queue.PublishAsk,
+		Record: func(id string) (*stdio.StateEntry, error) { return queue.RouterRecord(asker + "." + id) }}
+	return h
+}
+
+// reconcileEvery is how often the engine catches up its open asks from the router's records (a warrant heard while no
+// link was open, an ask past its expiry): besides each link's opening.
+const reconcileEvery = 5 * time.Minute
+
+func reconcileActs(ctx context.Context, h *link.HandActs) {
+	t := time.NewTicker(reconcileEvery)
+	defer t.Stop()
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case <-t.C:
+			h.Reconcile()
+		}
+	}
+}

cmd/mesh-host/file_references_test.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -10,6 +11,7 @@ import (
 	"testing"
 
 	"git.novox.be/novox/mesh-sdk/go/declaration"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
 	"github.com/nats-io/nats.go"
 	"github.com/novox/mesh-host/internal/link"
 )
@@ -82,6 +84,77 @@ func TestADeclarationWithAFileByDigestAppliesFromTheObject(t *testing.T) {
 	if err != nil || string(got) != string(body) {
 		t.Errorf("1695/AC1: the file holds %d bytes (%v), want %d", len(got), err, len(body))
 	}
+
+	// Issue 924 (novox, 2026-10-29 01:16): the controller's sweep removed an object a composition the node ran still named,
+	// and the module's apply failed while it ran. Content the node once had is its own keep's, and the bus is not asked.
+	gone := aFilesLink{err: fmt.Errorf("the object %s was deleted from the bucket declaration-files-novox", name)}
+	never := []byte(strings.Repeat("never had here\n", 6000))
+	for _, row := range []struct {
+		name    string
+		raw     []byte
+		onDisk  []byte // nil removes the file
+		refused string // "" applies
+	}{
+		{"the file here drifted, its object deleted", raw, []byte("the module wrote it since"), ""},
+		{"the file here is gone, its object deleted", raw, nil, ""},
+		{"never had here, its object deleted", referenceDeclaration(target, never), nil, "never held it"},
+	} {
+		if row.onDisk == nil {
+			_ = os.Remove(target)
+		} else if err := os.WriteFile(target, row.onDisk, 0o600); err != nil {
+			t.Fatal(err)
+		}
+		report = applyAndKeep(link.WithFiles(context.Background(), gone), opts, row.raw, nil, nil, nil)
+		if row.refused == "" {
+			got, _ := os.ReadFile(target)
+			if report.Refused != "" || string(got) != string(body) {
+				t.Errorf("924: %s: refused %q, the file holds %d bytes; want it applied from the node's own keep",
+					row.name, report.Refused, len(got))
+			}
+		} else if !strings.Contains(report.Refused, row.refused) || !strings.Contains(report.Refused, "was deleted") {
+			t.Errorf("924: %s: refused %q; want a refusal saying the bucket and the keep both lack it", row.name, report.Refused)
+		}
+	}
+
+	// Issue 924, the live case: what runs came from the kept declaration, whose export names a digest swept long ago,
+	// while the node wrote a newer export since. Composed as it runs, the file names what the node wrote, and applies with
+	// no object; a file someone else changed since is left as named.
+	newer := []byte(strings.Repeat("the export the node wrote since\n", 3000))
+	newerName, _ := declaration.ObjectName(declaration.DigestOf(newer))
+	ctx = link.WithFiles(context.Background(), aFilesLink{objects: map[string][]byte{newerName: newer}})
+	if report = applyAndKeep(ctx, opts, referenceDeclaration(target, newer), nil, nil, nil); report.Refused != "" {
+		t.Fatalf("924: the newer export: %s", report.Refused)
+	}
+	stale := json.RawMessage(`{"id":"m.big","type":"file","path":"` + target + `","digest":"` + declaration.DigestOf(body) +
+		`","size":` + strconv.Itoa(len(body)) + `}`)
+	for _, row := range []struct {
+		name   string
+		edit   []byte // what someone else wrote there since; nil for nobody
+		digest string
+	}{
+		{"the file is what the node wrote", nil, declaration.DigestOf(newer)},
+		{"someone changed the file since", []byte("a hand edit"), declaration.DigestOf(body)},
+	} {
+		if row.edit != nil {
+			if err := os.WriteFile(target, row.edit, 0o600); err != nil {
+				t.Fatal(err)
+			}
+		}
+		runs := runsAsWritten([]delivery.Composed{{Node: "n", Module: "m", Resources: []json.RawMessage{stale}}}, opts.state)
+		var got struct {
+			Digest string `json:"digest"`
+		}
+		_ = json.Unmarshal(runs[0].Resources[0], &got)
+		if got.Digest != row.digest {
+			t.Errorf("924: %s: what runs names %s, want %s", row.name, got.Digest, row.digest)
+		}
+		if row.edit == nil {
+			raw := []byte(`{"declaration":1,"resources":[` + string(runs[0].Resources[0]) + `]}`)
+			if report = applyAndKeep(link.WithFiles(context.Background(), gone), opts, raw, nil, nil, nil); report.Refused != "" {
+				t.Errorf("924: %s: composed as it runs, refused %q; want applied with no object", row.name, report.Refused)
+			}
+		}
+	}
 }
 
 // 1695/AC8: the hand-run `apply <file>` and `reconcile` have no bus: a reference whose file here verifies is applied

cmd/mesh-host/filling.go

@@ -3,22 +3,25 @@ package main
 import (
 	"context"
 	"crypto/ed25519"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"path/filepath"
 	"sync/atomic"
 
 	"git.novox.be/novox/mesh-sdk/go/declaration"
+	"git.novox.be/novox/mesh-sdk/go/provisions"
 	"github.com/novox/mesh-host/internal/apply"
 	"github.com/novox/mesh-host/internal/filling"
+	"github.com/novox/mesh-host/internal/link"
 	"github.com/novox/mesh-host/internal/store"
 	"github.com/novox/mesh-host/internal/system"
 )
 
 // serveFilling writes filled files on the provisioner client's request for as long as this engine serves (novox/hq
 // ADR 0349 §4). A socket that cannot be served is said once, and this engine goes on applying.
-func serveFilling(ctx context.Context, opts options, signer ed25519.PublicKey, say func(string)) {
-	e := fillingEngine(opts, signer, say)
+func serveFilling(ctx context.Context, opts options, signer ed25519.PublicKey, queue *link.Session, node string, say func(string)) {
+	e := fillingEngine(opts, signer, provisionSecretsOn(queue, node, opts.state), say)
 	fillingNow.Store(e)
 	defer fillingNow.CompareAndSwap(e, nil)
 	if err := filling.Serve(ctx, filling.Socket, e, say); err != nil {
@@ -30,9 +33,10 @@ func serveFilling(ctx context.Context, opts options, signer ed25519.PublicKey, s
 var fillingNow atomic.Pointer[filling.Engine]
 
 // knockFilling tells the provisioner's client to fill again what the filling refused or failed and the declaration
-// applied now may let through (filling.Engine.Knock), once a module's apply or removal settled (agent.Env.Settled).
-// What it told, or why it could not, is said.
-func knockFilling(module string, say func(string)) {
+// applied now may let through (filling.Engine.Knock), after what runs changed: a module's apply or removal settled
+// (agent.Env.Settled, "<module> settled"), the haves were read at the start, or a module was taken as running
+// (agent.Env.RunsChanged, issue 924). What it told, or why it could not, is said.
+func knockFilling(after string, say func(string)) {
 	e := fillingNow.Load()
 	if e == nil {
 		return
@@ -40,16 +44,19 @@ func knockFilling(module string, say func(string)) {
 	told, err := e.Knock(filling.Socket)
 	switch {
 	case err != nil:
-		say(fmt.Sprintf("after %s settled: %v", module, err))
+		say(fmt.Sprintf("after %s: %v", after, err))
 	case told != "":
-		say(fmt.Sprintf("after %s settled, the provisioner's client is told to fill again: %s", module, told))
+		say(fmt.Sprintf("after %s, the provisioner's client is told to fill again: %s", after, told))
 	}
 }
 
 // fillingEngine is the write of a filled file as this engine does it: the declaration it keeps, verified, read under
 // the apply's lock — the same two locks every apply takes, the process's and the one beside the state — and the file
 // written through the apply (apply.WriteFilled), its outcome recorded in the node's state as an apply's is.
-func fillingEngine(opts options, signer ed25519.PublicKey, say func(string)) *filling.Engine {
+//
+// A provision's `${secret:}` the client left in the content is filled first (secrets, novox/hq ADR 0570 clause 6), and a
+// file so filled is written 0600 when the declaration gives no mode.
+func fillingEngine(opts options, signer ed25519.PublicKey, secrets provisionSecrets, say func(string)) *filling.Engine {
 	return &filling.Engine{
 		Declared: func() (*declaration.Declaration, error) {
 			return declaredNow(opts.state, signer)
@@ -73,8 +80,13 @@ func fillingEngine(opts options, signer ed25519.PublicKey, say func(string)) *fi
 			if err != nil {
 				return "", "", err
 			}
-			report, updated, writeErr := apply.WriteFilled(ctx, built, d, known, path, content, apply.ExecRunner,
-				announceOr(say), apply.KeepIn(filepath.Dir(opts.state)), apply.WindowsIn(filepath.Dir(opts.state)))
+			content, secret, err := secrets.fill(ctx, filledModule(d, path), content)
+			if err != nil {
+				return "", "", fmt.Errorf("%s was not written: %w", path, err)
+			}
+			report, updated, writeErr := apply.WriteFilledWith(ctx, built, d, known, path, content, apply.ExecRunner,
+				announceOr(say), apply.KeepIn(filepath.Dir(opts.state)), apply.WindowsIn(filepath.Dir(opts.state)),
+				apply.Filled{Secret: secret})
 			// Saved whichever way it went, as an apply's: what was written is on the machine either way.
 			if err := store.Save(opts.state, updated); err != nil {
 				return "", "", errors.Join(writeErr, errors.New("written, and the node's state could not be saved: "+
@@ -93,3 +105,57 @@ func fillingEngine(opts options, signer ed25519.PublicKey, say func(string)) *fi
 		},
 	}
 }
+
+// filledModule is the module whose file the declaration declares at path, or "" when none or several do.
+func filledModule(d *declaration.Declaration, path string) string {
+	module := ""
+	for _, r := range d.Resources {
+		if f, ok := r.(*declaration.File); ok && f.Path == path {
+			if module != "" {
+				return ""
+			}
+			module, _ = d.ModuleOfID(f.ID)
+		}
+	}
+	return module
+}
+
+// provisionSecretsOn reads provisions and asks the vault over the link, and opens with this machine's sealing key.
+func provisionSecretsOn(queue *link.Session, node, statePath string) provisionSecrets {
+	p := provisionSecrets{node: node, open: sealOpener(statePath)}
+	if queue == nil {
+		return p
+	}
+	// What the bus holds under prefix, read by a watch to its caught-up mark: no poll, no list of every key.
+	p.list = func(ctx context.Context, prefix string) (map[string][]byte, error) {
+		wctx, cancel := context.WithCancel(ctx)
+		defer cancel()
+		updates, err := queue.KVWatch(wctx, provisions.ProvisionsBucket, prefix+">")
+		if err != nil {
+			return nil, err
+		}
+		out := map[string][]byte{}
+		for {
+			select {
+			case <-ctx.Done():
+				return nil, ctx.Err()
+			case u, ok := <-updates:
+				if !ok {
+					return nil, fmt.Errorf("the watch of %s ended before it caught up", provisions.ProvisionsBucket)
+				}
+				switch {
+				case u.Caught:
+					return out, nil
+				case u.Deleted:
+					delete(out, u.Key)
+				default:
+					out[u.Key] = u.Value
+				}
+			}
+		}
+	}
+	p.own = func(ctx context.Context, args map[string]any) (json.RawMessage, error) {
+		return queue.AskVault(ctx, "own", args)
+	}
+	return p
+}

cmd/mesh-host/filling_test.go

@@ -7,9 +7,12 @@ import (
 	"os"
 	"os/user"
 	"path/filepath"
+	"strings"
 	"testing"
 	"time"
 
+	"git.novox.be/novox/mesh-sdk/go/provisions"
+
 	"github.com/novox/mesh-host/internal/filling"
 	"github.com/novox/mesh-host/internal/store"
 )
@@ -45,7 +48,34 @@ func TestAWriteAndAnApplyOfTheSameFileSerialise(t *testing.T) {
 		store.Declared{Declaration: raw, Signature: ed25519.Sign(private, raw)}); err != nil {
 		t.Fatal(err)
 	}
-	e := fillingEngine(opts, public, func(string) {})
+	// The provision m reads, as mesh-provisioner keeps it, and the vault's value of it, sealed to this machine (faked:
+	// the opener reads the box's "v").
+	provision := map[string]string{}
+	vaultName := "provision/n2/db"
+	secrets := provisionSecrets{node: "n1",
+		list: func(_ context.Context, prefix string) (map[string][]byte, error) {
+			out := map[string][]byte{}
+			for k, v := range provision {
+				if strings.HasPrefix(k, prefix) {
+					out[k] = []byte(v)
+				}
+			}
+			return out, nil
+		},
+		own: func(_ context.Context, args map[string]any) (json.RawMessage, error) {
+			raw, _ := json.Marshal(args)
+			var a struct{ Credentials []map[string]any }
+			_ = json.Unmarshal(raw, &a)
+			c := a.Credentials[0]
+			c["name"], c["generation"], c["sealed"] = vaultName, 2, map[string]string{"v": "s3cret"}
+			return json.Marshal(map[string]any{"node": "n1", "credentials": []any{c}})
+		},
+		open: func(sealed string) ([]byte, error) {
+			var b struct{ V string }
+			err := json.Unmarshal([]byte(sealed), &b)
+			return []byte(b.V), err
+		}}
+	e := fillingEngine(opts, public, secrets, func(string) {})
 	uid := uint32(os.Getuid())
 	if err := e.Accepts(uid); err != nil {
 		t.Fatal(err)
@@ -102,4 +132,75 @@ func TestAWriteAndAnApplyOfTheSameFileSerialise(t *testing.T) {
 	if a := <-done; a.Action != "updated" {
 		t.Fatalf("the second write: %+v", a)
 	}
+
+	// ADR 0570 clause 6: the client leaves a provision's `${secret:}` to the node-engine, which fills it at the write
+	// from the vault's value of a provided provision, and writes the file 0600; a provision not provided refuses it.
+	keyed := func(state string, ref bool, id, local string) string {
+		p := provisions.Provision{Provision: "db", Local: local, Consumer: provisions.End{Module: "m", Node: "n1"},
+			Provider: provisions.End{Module: "postgres", Node: "n2"}, State: state, At: time.Now()}
+		if state != provisions.Provided {
+			p.Why = "the provider has not answered"
+		}
+		if ref {
+			p.Reference = &provisions.Reference{ID: id, Generation: 2}
+		}
+		raw, err := provisions.Encode(p)
+		if err != nil {
+			t.Fatal(err)
+		}
+		return string(raw)
+	}
+	for _, tc := range []struct {
+		name, state string
+		ref         bool
+		content     string
+		want        string // the file after; "" keeps what was there
+		mode        os.FileMode
+		vault       string // the vault's credential name, when not the one the provision names
+		refID       string // the reference's id, when not the provision's shared value
+		local       string // the provision's local name (ADR 0094): the placeholder names it
+	}{
+		{name: "a provision not provided is refused", state: provisions.Asked, content: "password=${secret:db}\n"},
+		{name: "provided with no reference is refused", state: provisions.Provided, content: "password=${secret:db}\n"},
+		{name: "a reference to no credential of the provision is refused", state: provisions.Provided, ref: true,
+			refID: "provision/n9/db", content: "password=${secret:db}\n"},
+		{name: "a name no provision goes by is refused", state: provisions.Provided, ref: true, content: "password=${secret:other}\n"},
+		{name: "the vault's value is another than the provision names", state: provisions.Provided, ref: true,
+			vault: "pair/n2/db/n1/m", content: "password=${secret:db}\n"},
+		{name: "provided: filled at the write, 0600", state: provisions.Provided, ref: true,
+			content: "password=${secret:db}\n", want: "password=s3cret\n", mode: 0o600},
+		{name: "a local name is the provision's by its key", state: provisions.Provided, ref: true, local: "admin",
+			content: "admin=${secret:admin}\n", want: "admin=s3cret\n", mode: 0o600},
+		{name: "no placeholder is written as it came, as the declaration says", content: "plain\n", want: "plain\n", mode: 0o644},
+	} {
+		before, _ := os.ReadFile(path)
+		if tc.state != "" {
+			id := "provision/n2/db"
+			if tc.refID != "" {
+				id = tc.refID
+			}
+			clear(provision)
+			key := "n1.m.db"
+			if tc.local != "" {
+				key += "." + tc.local
+			}
+			provision[key] = keyed(tc.state, tc.ref, id, tc.local)
+		}
+		vaultName = "provision/n2/db"
+		if tc.vault != "" {
+			vaultName = tc.vault
+		}
+		a := e.Write(context.Background(), uid, filling.Request{Path: path, Content: []byte(tc.content)})
+		got, _ := os.ReadFile(path)
+		if tc.want == "" {
+			if a.Failed == "" && a.Refused == "" || string(got) != string(before) {
+				t.Errorf("%s: answered %+v, the file holds %q", tc.name, a, got)
+			}
+			continue
+		}
+		info, _ := os.Stat(path)
+		if a.Failed != "" || a.Refused != "" || string(got) != tc.want || info.Mode().Perm() != tc.mode {
+			t.Errorf("%s: answered %+v, the file holds %q, mode %v", tc.name, a, got, info.Mode())
+		}
+	}
 }

cmd/mesh-host/found.go

@@ -68,14 +68,23 @@ func foundDirectories(known store.State) []store.Applied {
 // known (novox/hq ADR 0272): typed on the control-node, from the operator's own account. The directory's
 // path is the resource's target beside the reason, never in it: the controller says a reason on the
 // operator's channel, which withholds a path (ADR 0234 §6), and keeps the target as evidence.
+//
+// From the lease write, heard as the engine hears it (meshTrust), the line has no answerer: the way out is the node
+// seat's hand-over with the directory's path, which asks the operator on their channel (novox/hq ADR 0563 §5).
 func handOverLine() string {
 	node, _ := foundNode.Load().(string)
 	if node == "" {
 		node = "<node>"
 	}
+	if t := foundTrust.Load(); t != nil && t.HandedAway() {
+		return fmt.Sprintf("`%s/node-engine.hand-over` with the directory's path, then your yes on your channel", node)
+	}
 	return fmt.Sprintf("`nox node hand-over %s <directory>` on the control-node", node)
 }
 
+// foundTrust is what the engine trusts, whose lease decides the way out a directory used as found names.
+var foundTrust atomic.Pointer[meshTrust]
+
 // withFoundDirectories adds to a statement every directory used as found, as its module's resource of kind
 // directory, unhealthy: the reason names its owner and mode as they are now, what was declared, and the line
 // that hands it over. The path is the target, which the controller keeps as evidence.
@@ -129,16 +138,30 @@ func foundNow() []store.Applied {
 // never follows a path it did not state: a hand-over is root giving a directory to an account at the next
 // apply, and a path that resolves elsewhere would give that elsewhere.
 func handOverFound(statePath, path, by string) (string, error) {
+	found, _, err := judgeFound(statePath, path)
+	if err != nil {
+		return "", err
+	}
+	if err := store.AddHandedOver(statePath, store.HandOver{ID: found.ID, Path: path, At: time.Now().UTC(), By: by}); err != nil {
+		return "", err
+	}
+	return fmt.Sprintf("%s (%s) is handed to the mesh by %s: the next apply gives it %s, and it is the mesh's from "+
+		"then on — removed when empty and no longer declared", path, found.ID, by, orUnsaid(found.Declared)), nil
+}
+
+// judgeFound is the judgement of a hand-over's path, recording nothing: the directory this machine uses as found at
+// that path, as the engine states it, and what is on disk there.
+func judgeFound(statePath, path string) (store.Applied, os.FileInfo, error) {
 	if !filepath.IsAbs(path) {
-		return "", fmt.Errorf("hand-over takes the directory's absolute path, and %q is not one; nothing was handed over", path)
+		return store.Applied{}, nil, fmt.Errorf("hand-over takes the directory's absolute path, and %q is not one; nothing was handed over", path)
 	}
 	if filepath.Clean(path) != path {
-		return "", fmt.Errorf("%q is not the directory's path as the engine states it (no `..`, no doubled or trailing "+
+		return store.Applied{}, nil, fmt.Errorf("%q is not the directory's path as the engine states it (no `..`, no doubled or trailing "+
 			"separator); nothing was handed over", path)
 	}
 	known, err := store.Load(statePath)
 	if err != nil {
-		return "", err
+		return store.Applied{}, nil, err
 	}
 	var found *store.Applied
 	for _, r := range foundDirectories(known) {
@@ -149,31 +172,27 @@ func handOverFound(statePath, path, by string) (string, error) {
 		}
 	}
 	if found == nil {
-		return "", errors.New(path + " is not a directory this machine uses as found (the module's condition names " +
+		return store.Applied{}, nil, errors.New(path + " is not a directory this machine uses as found (the module's condition names " +
 			"the ones that are); nothing was handed over")
 	}
 	info, err := os.Lstat(path)
 	switch {
 	case err != nil:
-		return "", fmt.Errorf("%s cannot be read on this machine: %v; nothing was handed over", path, err)
+		return store.Applied{}, nil, fmt.Errorf("%s cannot be read on this machine: %v; nothing was handed over", path, err)
 	case info.Mode()&os.ModeSymlink != 0:
-		return "", fmt.Errorf("%s is a link, and the mesh hands over no link (novox/hq ADR 0012); nothing was handed over", path)
+		return store.Applied{}, nil, fmt.Errorf("%s is a link, and the mesh hands over no link (novox/hq ADR 0012); nothing was handed over", path)
 	case !info.IsDir():
-		return "", fmt.Errorf("%s is not a directory on this machine; nothing was handed over", path)
+		return store.Applied{}, nil, fmt.Errorf("%s is not a directory on this machine; nothing was handed over", path)
 	}
 	resolved, err := filepath.EvalSymlinks(path)
 	if err != nil {
-		return "", fmt.Errorf("%s cannot be resolved on this machine: %v; nothing was handed over", path, err)
+		return store.Applied{}, nil, fmt.Errorf("%s cannot be resolved on this machine: %v; nothing was handed over", path, err)
 	}
 	if resolved != path {
-		return "", fmt.Errorf("%s is reached through a link (it is %s), and the mesh hands over nothing through one "+
+		return store.Applied{}, nil, fmt.Errorf("%s is reached through a link (it is %s), and the mesh hands over nothing through one "+
 			"(novox/hq issue 339); nothing was handed over", path, resolved)
 	}
-	if err := store.AddHandedOver(statePath, store.HandOver{ID: found.ID, Path: path, At: time.Now().UTC(), By: by}); err != nil {
-		return "", err
-	}
-	return fmt.Sprintf("%s (%s) is handed to the mesh by %s: the next apply gives it %s, and it is the mesh's from "+
-		"then on — removed when empty and no longer declared", path, found.ID, by, orUnsaid(found.Declared)), nil
+	return *found, info, nil
 }
 
 // handOverFrom is the engine's hand-over for the controller's ask: the state beside statePath, the path as asked.

cmd/mesh-host/found_test.go

@@ -40,6 +40,21 @@ func TestAFoundDirectoryIsStatedUnhealthy(t *testing.T) {
 		strings.Contains(r.Reason, "mesh-host") || strings.Contains(r.Reason, dir) {
 		t.Fatalf("the way out is not the operator's line, or carries the path: %q", r.Reason)
 	}
+	// ADR 0563 §5: from the lease write the remedy is the node seat's hand-over, answered on the operator's channel, and
+	// no longer the controller's terminal line; the lease is the one the engine hears.
+	handed := newMeshTrust(nil)
+	handed.handedAway = true
+	foundTrust.Store(handed)
+	if r := withFoundDirectories(&link.Health{}, foundDirectories(known)).Resources[0]; !strings.Contains(r.Reason,
+		"`laptop/node-engine.hand-over`") || strings.Contains(r.Reason, "nox node hand-over") || strings.Contains(r.Reason, dir) {
+		t.Fatalf("after the lease write the way out is %q", r.Reason)
+	}
+	foundTrust.Store(newMeshTrust(nil))
+	if r := withFoundDirectories(&link.Health{}, foundDirectories(known)).Resources[0]; !strings.Contains(r.Reason,
+		"`nox node hand-over laptop <directory>`") {
+		t.Fatalf("while the controller holds its lease the way out is %q", r.Reason)
+	}
+	foundTrust.Store((*meshTrust)(nil))
 	foundNode.Store("")
 	if r := withFoundDirectories(&link.Health{}, foundDirectories(known)).Resources[0]; !strings.Contains(r.Reason,
 		"`nox node hand-over <node> <directory>`") {

cmd/mesh-host/libraries_test.go

@@ -8,6 +8,8 @@ import (
 	"testing"
 	"time"
 
+	meshasker "git.novox.be/novox/mesh-sdk/go/asker"
+	"git.novox.be/novox/mesh-sdk/go/asks"
 	"git.novox.be/novox/mesh-sdk/go/declaration"
 	"github.com/novox/mesh-host/internal/apply"
 	"github.com/novox/mesh-host/internal/link"
@@ -53,4 +55,42 @@ func TestALibrarySaysItsWaitWithoutWordsToParse(t *testing.T) {
 	if strings.Contains(media.Reason, dir) || len(books.AccessWaits) != 1 || books.AccessWaits[0].Reason != link.WaitDisk {
 		t.Fatalf("a missing root does not wait for its disk, or a reason names a path: %+v %+v", books, media)
 	}
+	// 774 (ADR 0563 §4): the library's home engine asks its take of the operator itself, once: no second ask while one is
+	// open, nor after it ended; and a library waiting for its disk is not asked.
+	t.Run("the home engine asks the take once", func(t *testing.T) {
+		var asked []asks.Ask
+		state := &link.MemState{}
+		h := &link.HandActs{Node: "n1", State: state,
+			JudgeAccess: func(act, access string) (link.Judged, error) {
+				return link.Judged{Subject: access, Path: root, Sets: "the group mesh-media", Disk: "0:0 755"}, nil
+			},
+			AccessAct: func(link.AccessAct) (string, error) { return "taken", nil }}
+		h.Asker = &meshasker.Client{Module: asks.EngineAsker("n1"), State: state,
+			Publish: func(subject string, body any, id string) error {
+				if a, ok := body.(asks.Ask); ok {
+					asked = append(asked, a)
+				}
+				return nil
+			}}
+		waiting := keepWaiting(vs)
+		askTakes(h, waiting, nil)
+		askTakes(h, waiting, nil)
+		if len(waiting) != 1 || waiting[0] != "library:media" || len(asked) != 1 {
+			t.Fatalf("waiting %v asked %d times", waiting, len(asked))
+		}
+		h.Heard(asks.Warrant{Ask: asked[0].ID, Asker: asks.EngineAsker("n1"), Outcome: asks.OutcomeExpired, At: time.Now()})
+		askTakes(h, waiting, nil)
+		if len(asked) != 1 {
+			t.Fatalf("the take was asked again after its ask ended: %d", len(asked))
+		}
+		// Kept in a key of its own (rev-l3 round 1): the acts gone from the record never make it ask again.
+		keys, _ := state.Keys("act.")
+		for _, k := range keys {
+			_ = state.Delete(k)
+		}
+		askTakes(h, waiting, nil)
+		if len(asked) != 1 {
+			t.Fatalf("the take was asked again with the acts gone: %d", len(asked))
+		}
+	})
 }

cmd/mesh-host/main.go

@@ -516,7 +516,7 @@ func runApply(ctx context.Context, opts options, d *declaration.Declaration, raw
 
 	// A file given by digest is had before the plan is drawn from it (novox/hq ADR 0486 §1, issue 1695). This command has
 	// no link to the bus, so a file already here that verifies is used, and any other is refused: never written empty.
-	if err := apply.ResolveFileReferences(ctx, d, link.FilesFrom(ctx)); err != nil {
+	if err := apply.ResolveFileReferencesKept(ctx, d, link.FilesFrom(ctx), objectKeep(opts)); err != nil {
 		return fmt.Errorf("a file of this declaration could not be had by its digest: %w", err)
 	}
 
@@ -1105,10 +1105,17 @@ func runLink(ctx context.Context, opts options) error {
 	// the bus, answer what the controller asks of this machine, and say its facts: when a link opens, and when the
 	// controller asks.
 	proof := &proving{statePath: opts.state, version: runningVersion(), say: say}
+	// What this engine trusts a mesh signature from: the controller's key until its lease is handed away, and the vault's
+	// once read from its signers (novox/hq ADR 0550 §2).
+	trust := newMeshTrust(mine.Membership.Signer)
+	// And the way out a directory used as found names follows the lease it hears (novox/hq ADR 0563 §5).
+	foundTrust.Store(trust)
 	queue := &link.Session{
 		Membership: membership,
 		// And the public halves and certificate its record says (novox/hq ADR 0555 §3), read at each facts report.
-		Keys: recordKeys(opts.state),
+		Keys: recordKeys(opts.state, trust.Trusts),
+		// And the controller's key, read per signed ask: none once its lease is handed away (novox/hq ADR 0563 §7).
+		ControllerKey: trust.Controller,
 		// And the first have this build writes is what proves it to the launcher (ADR 0539 §9, ADR 0227 §8).
 		HaveWritten: proof.haveWritten,
 		// And the operator's hand-over of a directory used as found, carried by the controller from the
@@ -1129,6 +1136,10 @@ func runLink(ctx context.Context, opts options) error {
 		Say:       say,
 		Timeout:   opts.timeout,
 	}
+	// And the node seat node-engine this engine holds (novox/hq ADR 0563): its verbs on every link, its own asks to the
+	// operator under node-engine-<node>, and its acts kept beside its state.
+	queue.Acts = engineActs(opts, mine.Node, queue, setuidSearch)
+	go reconcileActs(ctx, queue.Acts)
 	current := &agentNow{}
 	setRunsHere(runsFromAgent(current))
 	factsOfNow := func(ctx context.Context, ag *agent.Agent) {
@@ -1173,7 +1184,10 @@ func runLink(ctx context.Context, opts options) error {
 	}
 	// The node follows its wants: one module at a time from the composition its want names (novox/hq ADR 0539), and the
 	// busy containers are asked for again soon (ADR 0360 §11).
-	go nodeAgent(aside, opts, mine.Membership.Signer, queue, sched, say, afterApply, current, factsOfNow)
+	// And what it trusts, followed on the bus, said in its record whenever it changes (ADR 0550 §2).
+	trust.onChange(func() { factsOfNow(aside, current.get()) })
+	go followTrust(aside, queue, trust, say)
+	go nodeAgent(aside, opts, mine.Membership.Signer, trust, queue, sched, say, afterApply, current, factsOfNow)
 	go busyPasses(aside, func() {
 		if ag := current.get(); ag != nil {
 			ag.Retry(busyModules()...)
@@ -1186,7 +1200,7 @@ func runLink(ctx context.Context, opts options) error {
 	go serveMeshCLI(aside, queue, say)
 	// And a filled file is written on the provisioner client's request, one at a time with the apply (novox/hq ADR
 	// 0349 §4).
-	go serveFilling(aside, opts, mine.Membership.Signer, say)
+	go serveFilling(aside, opts, mine.Membership.Signer, queue, mine.Node, say)
 
 	held := link.HoldRoused(aside, membership, queue, say, opts.timeout, rousedBySignal(ctx))
 	// **Cleanly**, or the launcher counts standing aside as a crash and rolls the new host back
@@ -1339,6 +1353,8 @@ func judgeWhatRuns(ctx context.Context, j *liveness.Judge, queue *link.Session,
 	var lastSaid time.Time
 	owed := true
 	spaced := 1.0
+	// healthUnwritten is why the health report was last not written, said once each time it changes.
+	var healthUnwritten string
 	// A module whose change ended unjudged is looked at and said at once (review of fix 15): a module with nothing
 	// long-running is then ok within a look of its apply, not at the five-minute statement.
 	var nudged <-chan struct{}
@@ -1370,6 +1386,7 @@ func judgeWhatRuns(ctx context.Context, j *liveness.Judge, queue *link.Session,
 		if a := accountJudge; a != nil {
 			as, accountsChanged := a.Look(ctx)
 			accountSt = &as
+			lastAccounts.Store(&as)
 			owed = owed || accountsChanged
 			if accountsChanged {
 				for _, v := range as.Accounts {
@@ -1384,6 +1401,9 @@ func judgeWhatRuns(ctx context.Context, j *liveness.Judge, queue *link.Session,
 		accessSt, accessesChanged := accesses.look(time.Now())
 		keeping.poke(ctx)
 		owed = owed || accessesChanged
+		// And a library whose root holds data outside its group is asked of the operator by this engine, once (novox/hq
+		// ADR 0563 §4).
+		askTakes(queue.Acts, keepWaiting(accessSt), say)
 		if accessesChanged {
 			for _, v := range accessSt {
 				if v.State != link.StateHealthy {
@@ -1418,6 +1438,11 @@ func judgeWhatRuns(ctx context.Context, j *liveness.Judge, queue *link.Session,
 		healthy := st.Healthy() && (netSt == nil || netSt.State != network.Unhealthy) &&
 			(unitSt == nil || len(unitSt.Failed) == 0) && (accountSt == nil || accountSt.Healthy()) && len(found) == 0 &&
 			accessesHealthy(accessSt)
+		h := *withAccesses(withFoundDirectories(withAccounts(withUnits(healthAsReported(st, netSt),
+			unitSt), accountSt), found), accessSt)
+		// The node's own health report in its key on the bus, compared on every look and written only when what it says
+		// changed (issue 774): what the watchman raises the machine's alerts from, without the controller.
+		writeHealthReport(ctx, queue, h, netSt, &healthUnwritten, say)
 		if !owed && !(!healthy && since >= sayUnhealthyAgain) && since < sayAnyway {
 			continue
 		}
@@ -1444,13 +1469,40 @@ func judgeWhatRuns(ctx context.Context, j *liveness.Judge, queue *link.Session,
 				reconcile(inactive...)
 			}
 		}
-		if queue.SayHealth(ctx, *withAccesses(withFoundDirectories(withAccounts(withUnits(healthAsReported(st, netSt),
-			unitSt), accountSt), found), accessSt)) {
+		if queue.SayHealth(ctx, h) {
 			lastSaid, owed = time.Now(), false
 		}
 	}
 }
 
+// writeHealthReport writes this node's health report to its key (link.WriteNodeHealth) when it changed. Why it could
+// not is said once per reason, and said again when it is written after all.
+func writeHealthReport(ctx context.Context, queue *link.Session, h link.Health, ns *network.Statement, unwritten *string,
+	say link.Announce) {
+	if queue == nil {
+		return
+	}
+	var peers []link.PeerSeen
+	if ns != nil {
+		for _, p := range ns.Peers {
+			peers = append(peers, link.PeerSeen{Key: p.Key, Addresses: p.Addresses, Seen: p.Seen})
+		}
+	}
+	var machines link.Machines
+	if c := machinesNow.Load(); c != nil {
+		machines.ByAddress, machines.Hub = c.Machines()
+	}
+	_, err := queue.WriteNodeHealth(ctx, link.NodeHealthOf(queue.Membership.Node, h, peers, machines))
+	switch {
+	case err != nil && err.Error() != *unwritten:
+		*unwritten = err.Error()
+		say("this machine's health report is not written to the bus: " + err.Error())
+	case err == nil && *unwritten != "":
+		*unwritten = ""
+		say("this machine's health report is written to the bus again")
+	}
+}
+
 // healthAsReported is a statement as the report and the event carry it.
 func healthAsReported(st liveness.Statement, ns *network.Statement) *link.Health {
 	// LibraryContract: this engine reads a resource's declared `health` and judges it (ADR 0240 Phase B), judges a
@@ -1646,6 +1698,15 @@ func announceOr(say link.Announce) func(string) {
 // run by hand beside this service — the lock beside the state does the same (store.Lock).
 var applying sync.Mutex
 
+// objectKeep is the node's own keep of the objects its compositions name by digest, beside its state (apply.ObjectKeep,
+// issue 924): a composition the node once applied never again needs the controller's bucket to hold its files.
+func objectKeep(opts options) *apply.ObjectKeep {
+	if opts.state == "" {
+		return nil
+	}
+	return apply.KeepObjectsIn(filepath.Join(filepath.Dir(opts.state), "objects"))
+}
+
 // appliedModule is how the apply of one module's declaration came out.
 type appliedModule struct {
 	// Refused is why nothing was applied, when nothing was.
@@ -1685,7 +1746,7 @@ func applyModuleHeld(ctx context.Context, opts options, declared *declaration.De
 
 	// **A file given by digest is fetched and verified before anything of the composition is applied** (novox/hq ADR
 	// 0486 §1, issue 1695): one object missing or differing refuses the module whole.
-	if err := apply.ResolveFileReferences(ctx, declared, link.FilesFrom(ctx)); err != nil {
+	if err := apply.ResolveFileReferencesKept(ctx, declared, link.FilesFrom(ctx), objectKeep(opts)); err != nil {
 		return appliedModule{Refused: "a file of this composition could not be had by its digest: " + err.Error()}
 	}
 
@@ -2167,9 +2228,12 @@ func withMissing(st liveness.Statement) liveness.Statement {
 // recordKeys reads the public halves of the node's keys and the certificate the mesh issued for its internal name from
 // its state directory (novox/hq ADR 0555 §3): what the node's record says of them. A key that cannot be read is left
 // empty, never invented; the certificate is there only after the first declaration that carried it.
-func recordKeys(state string) func() link.RecordKeys {
+func recordKeys(state string, trusts func() []string) func() link.RecordKeys {
 	return func() link.RecordKeys {
 		var k link.RecordKeys
+		if trusts != nil {
+			k.Trusts = trusts()
+		}
 		if id, err := identity.Load(identity.Path(state)); err == nil {
 			k.TunnelKey = id.Overlay.Public
 		}

cmd/mesh-host/nodeagent.go

@@ -5,12 +5,14 @@ import (
 	"crypto/ed25519"
 	"encoding/base64"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"os"
 	"path/filepath"
 	"sort"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"git.novox.be/novox/mesh-sdk/go/compose/frombus"
@@ -343,13 +345,14 @@ func resourcesOf(cs []delivery.Composed) []declaration.Resource {
 // controller's key the node was enrolled with (novox/hq ADR 0539 §3, §11); a node adopted later has it at its adoption.
 const operatorKeysFile = "operator-keys"
 
-// trustedKeys are the keys a composition may be signed by: the controller's, which the node was enrolled with, and the
-// operator's, read from operatorKeysFile each time it is asked, so a key that arrives while the agent runs is trusted at
-// the next composition. A file that cannot be read trusts the controller's alone, and says so.
-func trustedKeys(opts options, controller ed25519.PublicKey) func() []ed25519.PublicKey {
+// trustedKeys are the keys a composition may be signed by: the controller's, which the node was enrolled with, while the
+// controller holds its lease (ADR 0550 §2: trusted no more once it is handed away), and the operator's, read from
+// operatorKeysFile each time it is asked, so a key that arrives while the agent runs is trusted at the next composition.
+// A file that cannot be read trusts the controller's alone, and says so.
+func trustedKeys(opts options, controllerNow func() ed25519.PublicKey) func() []ed25519.PublicKey {
 	return func() []ed25519.PublicKey {
 		keys := []ed25519.PublicKey{}
-		if len(controller) == ed25519.PublicKeySize {
+		if controller := controllerNow(); len(controller) == ed25519.PublicKeySize {
 			keys = append(keys, controller)
 		}
 		raw, err := os.ReadFile(filepath.Join(filepath.Dir(opts.state), operatorKeysFile))
@@ -373,13 +376,16 @@ func trustedKeys(opts options, controller ed25519.PublicKey) func() []ed25519.Pu
 }
 
 // keptOnce reads the kept declaration once and splits it by module: its resources (the node's own are those that say
-// none, ADR 0539 §9) and its filled paths.
+// none, ADR 0539 §9) and its filled paths. Once the read is retired (keptRetired) nothing is read.
 func keptOnce(opts options, signer ed25519.PublicKey) func() (map[string][]json.RawMessage, map[string][]string) {
 	var once sync.Once
 	var by map[string][]json.RawMessage
 	var filled map[string][]string
 	return func() (map[string][]json.RawMessage, map[string][]string) {
 		once.Do(func() {
+			if keptRetired.Load() {
+				return
+			}
 			raw, err := store.LoadDeclared(store.DeclaredPath(opts.state), signer)
 			if err != nil {
 				return
@@ -429,7 +435,7 @@ func splitKept(raw []byte) (map[string][]json.RawMessage, map[string][]string) {
 // nodeAgent runs the node agent under the session's links for as long as ctx lasts: it waits for a link, follows the
 // node's wants and compositions on it, and begins again with the next link. A watch it cannot make (a bucket this node's
 // account may not read) is said, and tried again with a growing wait, as the link is.
-func nodeAgent(ctx context.Context, opts options, signer ed25519.PublicKey, session *link.Session, sched *apply.Scheduler,
+func nodeAgent(ctx context.Context, opts options, signer ed25519.PublicKey, trust *meshTrust, session *link.Session, sched *apply.Scheduler,
 	say link.Announce, afterApply func(), current *agentNow, sayFacts func(ctx context.Context, ag *agent.Agent)) {
 	wait := 2 * time.Second
 	for ctx.Err() == nil {
@@ -446,6 +452,18 @@ func nodeAgent(ctx context.Context, opts options, signer ed25519.PublicKey, sess
 			return
 		}
 		var ag *agent.Agent
+		// The kept release-5 declaration is no longer read once every module the seat's placement puts here has a have of its
+		// own (ADR 0550 §2: its signature is the controller's, trusted no more after the lease write).
+		// Nor before this engine keeps the node's own as it runs (applied/node.json): until then the kept declaration is the one
+		// record of what the node's own composition carries, its folded modules among them (issue 774, review of the
+		// re-land, round 1: novox's first start would compose its own with nats running nothing).
+		if retired, why := placedAllHave(linked, session, node); retired && !keptRetired.Load() {
+			if !appliedStoreFor(opts.state).holds(agent.NodeModule) {
+				say("the kept declaration is still read: " + why + ", but this engine keeps no node's own composition yet")
+			} else if !keptRetired.Swap(true) {
+				say("the kept declaration is no longer read: " + why)
+			}
+		}
 		kept := keptOnce(opts, signer)
 		// The mesh's own certificate the declaration kept from before carries, kept for the record before this machine
 		// composes its own (ADR 0555 §3): without it a module that asks for a certificate would be stood in for.
@@ -458,7 +476,7 @@ func nodeAgent(ctx context.Context, opts options, signer ed25519.PublicKey, sess
 		}
 		// The bus's user list, written alone from the newest composition of the bus module (ADR 0547 §8): on every
 		// node, and a node whose compositions carry no list writes nothing.
-		users := userListFollower(opts, session, composedBucket, trustedKeys(opts, signer), say, func() {
+		users := userListFollower(opts, session, composedBucket, trustedKeys(opts, trust.Controller), say, func() {
 			// This engine wrote the list, so the bus reloads its accounts and answers no JetStream request for a few
 			// seconds: what failed in them is tried again once that is over, not at its next wait.
 			time.AfterFunc(reloadSettles, func() {
@@ -483,7 +501,10 @@ func nodeAgent(ctx context.Context, opts options, signer ed25519.PublicKey, sess
 			// The same kept declaration's filled paths, so a module still running from it keeps its files filled.
 			KeptFilled: func() map[string][]string { _, filled := kept(); return filled },
 			Recorded:   recordedIn(opts.state, say),
-			Inactive:   inactiveIn(&liveness.Exec{Run: apply.ExecRunner, System: builtFor}, heldBy(apply.WindowsIn(filepath.Dir(opts.state)))),
+			// What this engine applied, kept on the machine and read at the start, so what runs is known before the node
+			// composes its own (issue 774).
+			Applied:  appliedStoreFor(opts.state),
+			Inactive: inactiveIn(&liveness.Exec{Run: apply.ExecRunner, System: builtFor}, heldBy(apply.WindowsIn(filepath.Dir(opts.state)))),
 			Revisions: func(ctx context.Context, key string) ([]agent.Update, error) {
 				got, err := session.KVHistory(ctx, composedBucket, key)
 				if err != nil {
@@ -495,12 +516,15 @@ func nodeAgent(ctx context.Context, opts options, signer ed25519.PublicKey, sess
 				}
 				return out, nil
 			},
-			Trusted: trustedKeys(opts, signer),
+			Trusted: trustedKeys(opts, trust.Controller),
 			Backup:  backupNode(session),
 			// What the filling refused before this apply may be named now: the provisioner's client is told to fill
 			// again (ace, 2026-10-25 21:17).
-			Settled: func(module string) { knockFilling(module, say) },
-			Say:     say,
+			Settled: func(module string) { knockFilling(module+" settled", say) },
+			// And once the haves are read at the start, and whenever a module is taken as running without an apply, so
+			// a refusal from the engine's start does not wait for some module to settle (issue 924).
+			RunsChanged: func(why string) { knockFilling(why, say) },
+			Say:         say,
 			// A failure of the bus not answering for a moment is tried again: 2 s, 5 s, 15 s, 60 s, then every 5 min.
 			Backoff: link.Backoff,
 			Apply: func(ctx context.Context, c delivery.Composed, others []delivery.Composed) agent.Result {
@@ -512,7 +536,7 @@ func nodeAgent(ctx context.Context, opts options, signer ed25519.PublicKey, sess
 				if herr != nil {
 					res = failedWith(herr.Error())
 				} else {
-					res = applyComposition(actx, opts, held, others, sched, say)
+					res = applyComposition(actx, opts, held, others, ag.Placed(scopeName(c)), ag.RemovedByWant(), sched, say)
 				}
 				done()
 				// The mesh's own certificate it carries is kept for this machine's record (ADR 0555 §3).
@@ -531,7 +555,7 @@ func nodeAgent(ctx context.Context, opts options, signer ed25519.PublicKey, sess
 			},
 			Remove: func(ctx context.Context, module string, others []delivery.Composed) agent.Result {
 				actx, done := applyContext(session.WithLink(ctx))
-				res := removeComposition(actx, opts, module, others, sched, say)
+				res := removeComposition(actx, opts, module, others, ag.Placed(module), sched, say)
 				done()
 				afterApply()
 				sayFacts(ctx, ag)
@@ -549,7 +573,7 @@ func nodeAgent(ctx context.Context, opts options, signer ed25519.PublicKey, sess
 		hooks := composerHooks{
 			running: func() []delivery.Composed {
 				if now := own.get(); now != nil {
-					return now.Everything()
+					return runsAsWritten(now.Everything(), opts.state)
 				}
 				return nil
 			},
@@ -572,11 +596,17 @@ func nodeAgent(ctx context.Context, opts options, signer ed25519.PublicKey, sess
 					now.NotComposedEach(run, why, held) // a module held alone marks that module, never the others (issue 1126)
 				}
 			},
+			// And the vault's authority beside the controller's, and this node's certificate asked of the vault when a
+			// module here asks for one (ADR 0550 §2).
+			vaultAuthority: trust.VaultAuthority,
+			certify: func(ctx context.Context) error {
+				return certifyThisNode(ctx, opts.state, node, trust, session.AskVault, func() { sayFacts(ctx, ag) })
+			},
 		}
 		// And its answer to every placement candidate, placed or not, applying nothing (novox/hq ADR 0559 §4): written into
 		// its own key, `<node>.node`, under candidates.
 		shadowHooks := hooks
-		shadowHooks.refused = nil
+		shadowHooks.refused, shadowHooks.certify = nil, nil
 		shadowEnv := composerEnv(session, node, say, shadowHooks)
 		// And, after each answer, what runs of an own secret the answer says the vault holds another value of, handed to
 		// the vault while the node applies the controller's compositions (issue 1126, cause C4; ownresync).
@@ -596,8 +626,10 @@ func nodeAgent(ctx context.Context, opts options, signer ed25519.PublicKey, sess
 			continue
 		}
 		if composer != nil {
+			machinesNow.Store(composer) // the machines a failing network part points at, by the placements (issue 774)
 			composes.set(delivery.ComposesOwn)
 			env.Composed, env.SelfComposed, env.Trusted, env.Policy = composer, true, nil, composer.Policy
+			env.HoldsData = composer.HoldsData // what runs from the kept declaration says Data as its manifest does
 			session.NoteComposes(linked, delivery.ComposesOwn, why)
 			// And once the catalogue no longer places it, the agent begins again on the controller's compositions: the
 			// placement key deleted ends this run, the way back (issue 1126, the seed's revert).
@@ -663,7 +695,13 @@ func (c *agentNow) get() *agent.Agent {
 }
 
 // applyComposition applies one composition: a module's, or the node's own.
-func applyComposition(ctx context.Context, opts options, c delivery.Composed, others []delivery.Composed,
+//
+// placed is the modules a want still places here besides this one: none of their resources is removed by this apply,
+// which is refused instead (issue 774).
+//
+// removed is the modules whose want says removed: in the node's own apply, a resource of any other module goes only when
+// its module is among them (issue 774).
+func applyComposition(ctx context.Context, opts options, c delivery.Composed, others []delivery.Composed, placed, removed map[string]bool,
 	sched *apply.Scheduler, say link.Announce) agent.Result {
 	name := scopeName(c)
 	if c.Module == "" {
@@ -679,7 +717,13 @@ func applyComposition(ctx context.Context, opts options, c delivery.Composed, ot
 	if err := refuseEmptyWrites(d); err != nil {
 		return failedWith(err.Error())
 	}
-	scope := apply.Scope{Module: name, Others: resourcesOf(others)}
+	scope := apply.Scope{Module: name, Others: resourcesOf(others), Placed: placed}
+	if name == agent.NodeModule {
+		scope.RemovedByWant = removed
+		if scope.RemovedByWant == nil {
+			scope.RemovedByWant = map[string]bool{}
+		}
+	}
 	got := applyModuleHeld(ctx, opts, d, &scope, sched, say)
 	if got.Refused != "" {
 		return failedWith(got.Refused)
@@ -698,9 +742,9 @@ func applyComposition(ctx context.Context, opts options, c delivery.Composed, ot
 }
 
 // removeComposition removes one module's own resources and nothing of another's.
-func removeComposition(ctx context.Context, opts options, module string, others []delivery.Composed,
+func removeComposition(ctx context.Context, opts options, module string, others []delivery.Composed, placed map[string]bool,
 	sched *apply.Scheduler, say link.Announce) agent.Result {
-	scope := apply.Scope{Module: module, Others: resourcesOf(others)}
+	scope := apply.Scope{Module: module, Others: resourcesOf(others), Placed: placed}
 	got := applyModuleHeld(ctx, opts, &declaration.Declaration{Version: declaration.Version}, &scope, sched, say)
 	switch {
 	case got.Refused != "":
@@ -725,8 +769,23 @@ func busyModules() []string {
 	return out
 }
 
-// keptDeclaration is the declaration the node kept before the switch, verified with the mesh's key when it is given.
+// machinesNow is the composer whose placements name the mesh's machines by address, for the health report's targets
+// (writeHealthReport); nil on a node that does not compose its own, whose parts then name no target.
+var machinesNow atomic.Pointer[selfcompose.Composer]
+
+// keptRetired says the kept declaration is read no more: every module the seat's placement puts on this node has a have of
+// its own (placedAllHave), so what runs is the agent's alone (ADR 0550 §2, design 47's L3 s9).
+var keptRetired atomic.Bool
+
+// errKeptRetired is keptDeclaration's answer once the read is retired.
+var errKeptRetired = errors.New("the kept declaration is read no more: every module placed on this node has a have of its own")
+
+// keptDeclaration is the declaration the node kept before the switch, verified with the mesh's key when it is given;
+// once the read is retired, nothing is read.
 func keptDeclaration(statePath string, signer ed25519.PublicKey) (*declaration.Declaration, error) {
+	if keptRetired.Load() {
+		return nil, errKeptRetired
+	}
 	var raw []byte
 	if len(signer) > 0 {
 		var err error
@@ -903,6 +962,9 @@ type composerHooks struct {
 	unseal  func(string) ([]byte, error)
 	refused func(why string, held map[string]string)
 	held    func(module string) (delivery.Seals, []string, error)
+	// vaultAuthority and certify are selfcompose.Env's VaultAuthority and Certify.
+	vaultAuthority func() string
+	certify        func(ctx context.Context) error
 }
 
 func selfComposer(ctx context.Context, session *link.Session, node string, say func(string), hooks composerHooks) (*selfcompose.Composer, string) {
@@ -966,7 +1028,8 @@ func composerEnv(session *link.Session, node string, say func(string), hooks com
 		Hear: session.Hear,
 		// And a moved module's templates archive, in the artifact store, as every archive is fetched (issue 1126).
 		Fetch:   apply.Fetch,
-		Running: hooks.running, Unseal: hooks.unseal, Refused: hooks.refused, Held: hooks.held}
+		Running: hooks.running, Unseal: hooks.unseal, Refused: hooks.refused, Held: hooks.held,
+		VaultAuthority: hooks.vaultAuthority, Certify: hooks.certify}
 }
 
 // endWhenUnplaced calls stop once this node's placement key is deleted from the seat's placement (after the watch

cmd/mesh-host/nodeagent_integration_test.go

@@ -159,7 +159,8 @@ func (b *itBed) start(trustOperator bool) (stop func()) {
 	done := make(chan struct{})
 	go func() {
 		defer close(done)
-		nodeAgent(ctx, b.opts, b.controll.Public().(ed25519.PublicKey), b.session, nil, b.say, func() {},
+		controller := b.controll.Public().(ed25519.PublicKey)
+		nodeAgent(ctx, b.opts, controller, newMeshTrust(controller), b.session, nil, b.say, func() {},
 			&agentNow{}, func(context.Context, *agent.Agent) {})
 	}()
 	return func() { cancel(); <-done }

cmd/mesh-host/provision_secrets.go

@@ -0,0 +1,168 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"regexp"
+	"sort"
+	"strings"
+
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+	"git.novox.be/novox/mesh-sdk/go/provisions"
+)
+
+// provisionSecrets fills a provision's value into a file the provisioner's client hands the node-engine to write
+// (novox/hq ADR 0570 clause 6): the client fills the file but for each `${secret:<provision>}`, and the node-engine
+// fills those at the write, so the client never holds the value. A whole `secrets` file of a handed consumer is the
+// placeholder alone.
+//
+// A placeholder names the credential as the module calls it, `${secret:<name>}` (catalogue.SecretLocal, ADR 0094): the
+// local name where the module keeps several values of one provision, else the provision. For each, it finds the one
+// provision key `<node>.<consumer>.<provision>[.<local>]` of the seat mesh-provisioner's state `provisions` (clause 1)
+// going by that name, which must be `provided` and carry the vault's reference; asks the vault for that pair
+// credential sealed to this machine's key (the verb `own`, ADR 0349 §11 with the node-engine standing for the client,
+// ADR 0550 §5); and opens it with this machine's sealing key. Anything short of that refuses the write, naming the
+// provision and why: a file written with a placeholder left in it, or with no value, is a module that starts and cannot
+// connect.
+type provisionSecrets struct {
+	node string
+	// list is every key of mesh-provisioner's `provisions` under prefix (`<node>.<consumer>.`), by key: what this
+	// engine may read, its own node's (`<node>.>`).
+	list func(ctx context.Context, prefix string) (map[string][]byte, error)
+	// own asks the vault's verb `own` in this engine's name.
+	own func(ctx context.Context, args map[string]any) (json.RawMessage, error)
+	// open opens a value sealed to this machine.
+	open func(sealed string) ([]byte, error)
+}
+
+// secretPlaceholder is `${secret:<name>}`.
+var secretPlaceholder = regexp.MustCompile(`\$\{secret:([A-Za-z0-9_-]+)\}`)
+
+// fill is content with each provision placeholder of module's filled, and whether any was.
+func (p provisionSecrets) fill(ctx context.Context, module string, content []byte) ([]byte, bool, error) {
+	found := secretPlaceholder.FindAllSubmatch(content, -1)
+	if len(found) == 0 {
+		return content, false, nil
+	}
+	if module == "" {
+		return nil, false, fmt.Errorf("the file names %d provision secret(s) and belongs to no module, so whose they are is not known", len(found))
+	}
+	if p.list == nil || p.own == nil || p.open == nil {
+		return nil, false, fmt.Errorf("%s's provisions cannot be read on this machine: the node-engine is not linked to the mesh", module)
+	}
+	prefix := p.node + "." + module + "."
+	keys, err := p.list(ctx, prefix)
+	if err != nil {
+		return nil, false, fmt.Errorf("%s's provisions cannot be read: %w", module, err)
+	}
+	out := string(content)
+	done := map[string]bool{}
+	for _, f := range found {
+		whole, name := string(f[0]), string(f[1])
+		if done[whole] {
+			continue
+		}
+		done[whole] = true
+		pr, key, err := byName(keys, name)
+		if err != nil {
+			return nil, false, fmt.Errorf("%s's secret %q: %w", module, name, err)
+		}
+		value, err := p.value(ctx, key, pr)
+		if err != nil {
+			return nil, false, err
+		}
+		out = strings.ReplaceAll(out, whole, string(value))
+	}
+	return []byte(out), true, nil
+}
+
+// byName is the one provision of keys the module calls name (catalogue.SecretLocal), and its key.
+func byName(keys map[string][]byte, name string) (provisions.Provision, string, error) {
+	var hit []string
+	var got provisions.Provision
+	for key, raw := range keys {
+		pr, err := provisions.Decode(raw)
+		if err != nil {
+			return provisions.Provision{}, "", fmt.Errorf("the provision %s: %w", key, err)
+		}
+		if catalogue.SecretLocal(pr.Provision, pr.Local) == name {
+			hit, got = append(hit, key), pr
+		}
+	}
+	switch len(hit) {
+	case 0:
+		return provisions.Provision{}, "", fmt.Errorf("no provision of %s goes by that name: nothing asks for it", provisions.ProvisionsRead)
+	case 1:
+		return got, hit[0], nil
+	}
+	sort.Strings(hit)
+	return provisions.Provision{}, "", fmt.Errorf("the provisions %s all go by that name", strings.Join(hit, ", "))
+}
+
+// value is one provision's value on this node, opened.
+func (p provisionSecrets) value(ctx context.Context, key string, pr provisions.Provision) ([]byte, error) {
+	if pr.State != provisions.Provided || pr.Reference == nil {
+		why := pr.State
+		if pr.Why != "" {
+			why += ": " + pr.Why
+		}
+		if pr.State == provisions.Provided {
+			why = "provided with no reference to the vault's value"
+		}
+		return nil, fmt.Errorf("the provision %s is %s, so its value is not written yet", key, why)
+	}
+	// The reference names a credential of this provision, as the vault names it (provisions.VaultName).
+	ours := false
+	for _, form := range []string{provisions.FormPair, provisions.FormShared, provisions.FormIssued} {
+		ours = ours || provisions.VaultName(form, pr) == pr.Reference.ID
+	}
+	if !ours {
+		return nil, fmt.Errorf("the provision %s names the vault's %s, which is no credential of it", key, pr.Reference.ID)
+	}
+	module, provision, local := pr.Consumer.Module, pr.Provision, pr.Local
+	type asked struct {
+		Role           string `json:"role"`
+		Provision      string `json:"provision"`
+		Consumer       string `json:"consumer"`
+		ConsumerModule string `json:"consumer_module"`
+		Provider       string `json:"provider"`
+		Local          string `json:"local,omitempty"`
+	}
+	ask := asked{Role: "consumer", Provision: provision, Consumer: p.node, ConsumerModule: module, Provider: pr.Provider.Node, Local: local}
+	answer, err := p.own(ctx, map[string]any{"credentials": []asked{ask}})
+	if err != nil {
+		return nil, fmt.Errorf("the vault's value of %s: %w", key, err)
+	}
+	var a struct {
+		Node        string `json:"node"`
+		Credentials []struct {
+			asked
+			Name       string          `json:"name"`
+			Generation int             `json:"generation"`
+			Sealed     json.RawMessage `json:"sealed"`
+		} `json:"credentials"`
+	}
+	if err := json.Unmarshal(answer, &a); err != nil {
+		return nil, fmt.Errorf("the vault's answer for %s is not one: %w", key, err)
+	}
+	if a.Node != p.node {
+		return nil, fmt.Errorf("the vault answered %s's credentials for %s on %s", a.Node, key, p.node)
+	}
+	for _, c := range a.Credentials {
+		if c.asked != ask {
+			continue
+		}
+		// The value the provision names, by the vault's credential name and its generation (clause 6): another is refused.
+		if c.Name != pr.Reference.ID || c.Generation != pr.Reference.Generation {
+			return nil, fmt.Errorf("the vault answered %s generation %d for %s, and the provision names %s generation %d: "+
+				"nothing is written until they agree", c.Name, c.Generation, key, pr.Reference.ID, pr.Reference.Generation)
+		}
+		value, err := p.open(string(c.Sealed))
+		if err != nil {
+			return nil, fmt.Errorf("the vault's value of %s does not open on this machine: %w", key, err)
+		}
+		return value, nil
+	}
+	return nil, fmt.Errorf("the vault answered no value of %s for this machine", key)
+}

cmd/mesh-host/runs_as_written.go

@@ -0,0 +1,88 @@
+package main
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"os"
+
+	"git.novox.be/novox/mesh-sdk/go/declaration"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+
+	"github.com/novox/mesh-host/internal/store"
+)
+
+// runsAsWritten is what the node runs as the composer reads it (selfcompose.Env.Running), with every file given by digest
+// named as this node last wrote it, where the two differ (issue 924, novox 2026-10-29 01:16). What runs of a module the
+// agent has not applied since its start can come from the kept declaration, older than the compositions applied since:
+// its export (mesh-vault.kept) then named a digest the controller's sweep had removed, while the file on disk was the
+// newer export the node wrote. A node composing its own carries such a file as it runs (mesh-sdk frombus keptOf), so it
+// names what is on disk: **only when the node's record says it wrote exactly that content there** (store Applied.Wrote,
+// Target), never a file someone else changed. A file that cannot be read, or that the record does not vouch for, is
+// left as the composition names it.
+func runsAsWritten(running []delivery.Composed, statePath string) []delivery.Composed {
+	if len(running) == 0 || statePath == "" {
+		return running
+	}
+	known, err := store.Load(statePath)
+	if err != nil {
+		return running
+	}
+	out := make([]delivery.Composed, len(running))
+	for i, c := range running {
+		out[i] = c
+		var changed []json.RawMessage
+		for j, raw := range c.Resources {
+			if fixed, ok := asWritten(raw, known); ok {
+				if changed == nil {
+					changed = append([]json.RawMessage(nil), c.Resources...)
+				}
+				changed[j] = fixed
+			}
+		}
+		if changed != nil {
+			out[i].Resources = changed
+		}
+	}
+	return out
+}
+
+// asWritten is the file resource raw named by the digest and size of what this node last wrote at its path, when raw is a
+// file given by another digest and the file there is what the record says the node wrote.
+func asWritten(raw json.RawMessage, known store.State) (json.RawMessage, bool) {
+	var fields map[string]json.RawMessage
+	if json.Unmarshal(raw, &fields) != nil {
+		return nil, false
+	}
+	var kind, id, path, digest string
+	_ = json.Unmarshal(fields["type"], &kind)
+	_ = json.Unmarshal(fields["id"], &id)
+	_ = json.Unmarshal(fields["path"], &path)
+	_ = json.Unmarshal(fields["digest"], &digest)
+	if kind != string(declaration.TypeFile) || digest == "" || path == "" {
+		return nil, false
+	}
+	rec, ok := known.Find(id)
+	if !ok || rec.Wrote == "" || rec.Target != path {
+		return nil, false
+	}
+	body, err := os.ReadFile(path)
+	if err != nil {
+		return nil, false
+	}
+	sum := sha256.Sum256(body)
+	if hex.EncodeToString(sum[:]) != rec.Wrote {
+		return nil, false // changed since the node wrote it: not the node's to vouch for
+	}
+	if now := declaration.DigestOf(body); now == digest {
+		return nil, false
+	} else {
+		fields["digest"], _ = json.Marshal(now)
+	}
+	fields["size"], _ = json.Marshal(len(body))
+	fixed, err := json.Marshal(fields)
+	if err != nil {
+		return nil, false
+	}
+	return fixed, true
+}

cmd/mesh-host/trust.go

@@ -0,0 +1,317 @@
+package main
+
+import (
+	"context"
+	"crypto/ed25519"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	"time"
+
+	"git.novox.be/novox/mesh-sdk/go/buscompose"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/overlay"
+
+	"github.com/novox/mesh-host/internal/identity"
+	"github.com/novox/mesh-host/internal/link"
+)
+
+// **What this engine trusts a mesh signature from** (novox/hq ADR 0550 §2; design 47's L3 item d). Two signers: the
+// controller's key, which the node was enrolled with (its membership's signer), and the vault's key, read from the vault's
+// state `signers`, which only the vault may write: the bus grants are its anchor, as the wants' and the placement's (the
+// lead's design limit, 2026-10-28). The controller's key is trusted until its lease is handed away, heard on the lease key
+// (buscompose.LeaseHandedAway) and never on a clock; from then the vault's alone. What it trusts now the node states in its
+// record (NodeRecord.Trusts), so the gate before the lease write reads every node's from the bus.
+type meshTrust struct {
+	mu         sync.Mutex
+	controller ed25519.PublicKey
+	handedAway bool
+	vault      ed25519.PublicKey
+	authority  string
+	// changed is told when what it trusts changed, so the record is written again.
+	changed func()
+}
+
+// newMeshTrust trusts the controller's key alone until the vault's is read.
+func newMeshTrust(controller ed25519.PublicKey) *meshTrust {
+	t := &meshTrust{}
+	if len(controller) == ed25519.PublicKeySize {
+		t.controller = controller
+	}
+	return t
+}
+
+// onChange names who is told when what it trusts changed.
+func (t *meshTrust) onChange(f func()) {
+	t.mu.Lock()
+	t.changed = f
+	t.mu.Unlock()
+}
+
+// Controller is the controller's key while the controller holds its lease, and nil once the lease is handed away.
+func (t *meshTrust) Controller() ed25519.PublicKey {
+	if t == nil {
+		return nil
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	if t.handedAway {
+		return nil
+	}
+	return t.controller
+}
+
+// HandedAway says the controller's lease was handed away, as heard on the lease key.
+func (t *meshTrust) HandedAway() bool {
+	if t == nil {
+		return false
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	return t.handedAway
+}
+
+// Signers are the keys a mesh signature is verified against now: the controller's while it holds the lease, and the
+// vault's once read.
+func (t *meshTrust) Signers() []delivery.Signer {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	var out []delivery.Signer
+	if t.controller != nil && !t.handedAway {
+		out = append(out, delivery.Signer{Name: delivery.SignerController, Key: t.controller})
+	}
+	if t.vault != nil {
+		out = append(out, delivery.Signer{Name: delivery.SignerVault, Key: t.vault})
+	}
+	return out
+}
+
+// Verify is the signer that signed msg as kind, or why none it trusts did.
+func (t *meshTrust) Verify(kind string, msg, sig []byte) (delivery.Signer, error) {
+	context, err := delivery.SignContext(kind)
+	if err != nil {
+		return delivery.Signer{}, err
+	}
+	return delivery.VerifyBy(t.Signers(), context, msg, sig)
+}
+
+// VaultAuthority is the vault's authority certificate as read from `signers`, or "".
+func (t *meshTrust) VaultAuthority() string {
+	if t == nil {
+		return ""
+	}
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	return t.authority
+}
+
+// Trusts is what the record says it trusts: each signer's key and the vault's authority, by fingerprint.
+func (t *meshTrust) Trusts() []string {
+	if t == nil {
+		return nil
+	}
+	authorities := map[string]string{}
+	if a := t.VaultAuthority(); a != "" {
+		authorities[delivery.SignerVault] = a
+	}
+	return delivery.Trusts(t.Signers(), authorities)
+}
+
+// change applies f under the lock and tells who follows when Trusts differs after it.
+func (t *meshTrust) change(f func()) {
+	before := strings.Join(t.Trusts(), "\n")
+	t.mu.Lock()
+	f()
+	changed := t.changed
+	t.mu.Unlock()
+	if strings.Join(t.Trusts(), "\n") != before && changed != nil {
+		changed()
+	}
+}
+
+// heardSigner takes one key of the vault's `signers`: its key or its authority, refused (and said) when it does not
+// check; a deleted key is no longer trusted.
+func (t *meshTrust) heardSigner(key string, value []byte, deleted bool, say link.Announce) {
+	switch key {
+	case delivery.SignersKeyKey:
+		var pub ed25519.PublicKey
+		if !deleted && len(value) > 0 {
+			k, err := delivery.DecodeSignerKey(value)
+			if err == nil {
+				pub, err = k.PublicKey()
+			}
+			if err != nil {
+				say("the vault's signing key in " + delivery.SignersRead + " is not trusted: " + err.Error())
+				return
+			}
+		}
+		t.change(func() { t.vault = pub })
+	case delivery.SignersAuthorityKey:
+		pem := ""
+		if !deleted && len(value) > 0 {
+			a, err := delivery.DecodeSignerAuthority(value)
+			if err != nil {
+				say("the vault's authority in " + delivery.SignersRead + " is not trusted: " + err.Error())
+				return
+			}
+			pem = a.Certificate
+		}
+		t.change(func() { t.authority = pem })
+	}
+}
+
+// heardLease takes the controller's lease key as read: once handed away to a holder that is no controller, the
+// controller's key is trusted no more. A lease that cannot be read changes nothing.
+func (t *meshTrust) heardLease(raw []byte, found bool, readErr error) {
+	if readErr != nil {
+		return
+	}
+	handed, _ := buscompose.LeaseHandedAway(raw, found, nil)
+	t.change(func() { t.handedAway = handed })
+}
+
+// trustFollowAgain bounds the wait before a watch that could not be made is tried again on the same link: the vault may
+// not serve `sign` yet, and until it does this node is not granted the reads.
+var trustFollowAgain = 2 * time.Minute
+
+// followTrust follows the vault's `signers` and the controller's lease on every link, as watches (never a poll), for as
+// long as ctx lasts. A watch that cannot be made is said once per reason and tried again.
+func followTrust(ctx context.Context, session *link.Session, trust *meshTrust, say link.Announce) {
+	said := ""
+	sayOnce := func(line string) {
+		if line != said {
+			said = line
+			if line != "" {
+				say(line)
+			}
+		}
+	}
+	for ctx.Err() == nil {
+		linked, cancel, err := session.WhenLinked(ctx)
+		if err != nil {
+			return
+		}
+		watching, stop := context.WithCancel(linked)
+		signers, serr := session.KVWatch(watching, delivery.SignersBucket, ">")
+		lease, lerr := session.KVWatch(watching, buscompose.LeaseBucket, buscompose.ControllerLeaseKey)
+		if serr != nil || lerr != nil {
+			stop()
+			sayOnce(fmt.Sprintf("what this node trusts a mesh signature from is not followed yet (the vault's signers: %v; "+
+				"the controller's lease: %v): it trusts what it last read, and looks again in %s", serr, lerr, trustFollowAgain))
+			signers, lease = nil, nil
+		} else {
+			sayOnce("")
+		}
+		for signers != nil || lease != nil {
+			select {
+			case u, ok := <-signers:
+				if !ok {
+					signers = nil
+					continue
+				}
+				if !u.Caught {
+					trust.heardSigner(u.Key, u.Value, u.Deleted, say)
+				}
+			case u, ok := <-lease:
+				if !ok {
+					lease = nil
+					continue
+				}
+				if !u.Caught {
+					trust.heardLease(u.Value, !u.Deleted && len(u.Value) > 0, nil)
+				}
+			}
+		}
+		stop()
+		select {
+		case <-linked.Done():
+		case <-time.After(trustFollowAgain):
+		}
+		cancel()
+	}
+}
+
+// placedAllHave says whether every module the seat mesh-placement places on node has a have of its own, read from the
+// bus: then the kept declaration is read no more (keptRetired). A node the seat does not place, or whose placement or haves
+// cannot be read, keeps reading it.
+func placedAllHave(ctx context.Context, session *link.Session, node string) (bool, string) {
+	key, err := delivery.PlacementKey(node)
+	if err != nil {
+		return false, err.Error()
+	}
+	h, err := session.KVHistory(ctx, delivery.PlacementBucket, key)
+	if err != nil || len(h) == 0 || h[len(h)-1].Deleted {
+		return false, "its placement is not read"
+	}
+	p, err := delivery.DecodePlacement(h[len(h)-1].Value)
+	if err != nil {
+		return false, err.Error()
+	}
+	return allHave(p, func(module string) (bool, error) {
+		_, ok, err := session.ReadHaveErr(ctx, module)
+		return ok, err
+	})
+}
+
+// allHave says whether has finds a have for every module p places, and why not.
+func allHave(p delivery.Placement, has func(module string) (bool, error)) (bool, string) {
+	if len(p.Modules) == 0 {
+		return false, "the seat mesh-placement places no module here"
+	}
+	for _, m := range p.Modules {
+		ok, err := has(m.Module)
+		if err != nil {
+			return false, "the have of " + m.Module + " is not read: " + err.Error()
+		}
+		if !ok {
+			return false, m.Module + " has no have yet"
+		}
+	}
+	return true, fmt.Sprintf("each of the %d modules placed here has a have of its own", len(p.Modules))
+}
+
+// certifyThisNode asks the vault's `sign` for this node's own certificate (kind node-certificate, ADR 0550 §2), checks
+// it is for this node's internal name and serving key and signed by the authority the answer names, which must be the
+// vault's this node trusts, keeps it where the record reads it, and writes the record again (written).
+func certifyThisNode(ctx context.Context, state, node string, trust *meshTrust,
+	ask func(ctx context.Context, verb string, args any) (json.RawMessage, error), written func()) error {
+	serving, err := identity.LoadServingKey(identity.ServingKeyPath(state))
+	if err != nil {
+		return err
+	}
+	key, err := base64.StdEncoding.DecodeString(serving.Public)
+	if err != nil || len(key) != ed25519.PublicKeySize {
+		return fmt.Errorf("this node's serving key is not an ed25519 key")
+	}
+	raw, err := ask(ctx, delivery.SignVerb, map[string]any{"kind": delivery.KindNodeCertificate, "node": node})
+	if err != nil {
+		return err
+	}
+	var a delivery.SignAnswer
+	if err := json.Unmarshal(raw, &a); err != nil {
+		return fmt.Errorf("the vault's answer is not a signing: %w", err)
+	}
+	trusted := trust.VaultAuthority()
+	if trusted == "" {
+		return fmt.Errorf("this node has read no authority of the vault's to check the certificate against")
+	}
+	if err := delivery.CheckNodeCertificate(a.Certificate, []string{trusted}, overlay.InternalName(node),
+		ed25519.PublicKey(key), time.Now()); err != nil {
+		return err
+	}
+	path := identity.CertificatePath(state)
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		return err
+	}
+	if err := os.WriteFile(path, []byte(a.Certificate), 0o644); err != nil {
+		return err
+	}
+	if written != nil {
+		written()
+	}
+	return nil
+}

cmd/mesh-host/units_test.go

@@ -1,6 +1,9 @@
 package main
 
 import (
+	"errors"
+	"os"
+	"path/filepath"
 	"strings"
 	"testing"
 	"time"
@@ -9,6 +12,7 @@ import (
 	"github.com/novox/mesh-host/internal/accounts"
 	"github.com/novox/mesh-host/internal/link"
 	"github.com/novox/mesh-host/internal/liveness"
+	"github.com/novox/mesh-host/internal/store"
 	"github.com/novox/mesh-host/internal/units"
 )
 
@@ -103,6 +107,61 @@ func TestTheStatementSaysAnAccountJudgedForRoot(t *testing.T) {
 	if got["claude-code.agent"] != "never" || got["openrazer.account"] != "" {
 		t.Fatalf("root said: %v", got)
 	}
+	// 774 (ADR 0563 §6): the node seat's root-free passes only on the engine's own positive verdict at most 15 minutes old
+	// with execute not served here; a stale, missing or negative verdict, or execute served, is no pass and says why.
+	t.Run("this machine's root-free", func(t *testing.T) {
+		agent := accounts.Verdict{Account: accounts.Account{Module: "claude-code", ID: "claude-code.agent", Name: "agent", Root: true},
+			State: accounts.Healthy, Since: at}
+		free := &accounts.Statement{At: at, Accounts: []accounts.Verdict{agent}}
+		for _, row := range []struct {
+			name   string
+			st     *accounts.Statement
+			after  time.Duration
+			served bool
+			free   bool
+			why    string
+		}{
+			{name: "a positive verdict", st: free, after: 14 * time.Minute, free: true, why: "the account agent cannot become root"},
+			{name: "a stale verdict", st: free, after: 16 * time.Minute, why: "more than 15 minutes ago"},
+			{name: "no verdict", st: nil, why: "judged no account yet"},
+			{name: "a way to root", st: as, why: "in the group docker, which grants root"},
+			{name: "no agent account", st: &accounts.Statement{At: at}, why: "agents run as the operator's account"},
+			{name: "execute served", st: free, served: true, why: "the login shell runs any command"},
+		} {
+			v := judgeRootFree("ace", row.st, at.Add(row.after), row.served, "the bus hears execute answered here")
+			if v.Free != row.free || !strings.Contains(v.Why, row.why) || v.Machine != "ace" {
+				t.Errorf("%s: %+v", row.name, v)
+			}
+		}
+		// execute is served while the holder's setting file says anything but withhold, or the bus hears it.
+		dir := t.TempDir()
+		statePath, conf := filepath.Join(dir, "state.json"), filepath.Join(dir, "tools.conf")
+		if err := store.Save(statePath, store.State{Resources: []store.Applied{{ID: "zsh.tools-conf", Type: "file", Target: conf}}}); err != nil {
+			t.Fatal(err)
+		}
+		quiet := func() (bool, error) { return false, nil }
+		for _, row := range []struct {
+			name, setting string
+			heard         func() (bool, error)
+			served        bool
+		}{
+			{name: "withheld and not heard", setting: "# the mesh's\nexecute=withhold\n", heard: quiet},
+			{name: "served", setting: "execute=serve\n", heard: quiet, served: true},
+			{name: "withheld and heard", setting: "execute=withhold\n", heard: func() (bool, error) { return true, nil }, served: true},
+			{name: "the bus not asked", setting: "execute=withhold\n", heard: func() (bool, error) { return false, errors.New("no link") }, served: true},
+			{name: "no setting file", heard: quiet, served: true},
+		} {
+			_ = os.Remove(conf)
+			if row.setting != "" {
+				if err := os.WriteFile(conf, []byte(row.setting), 0o644); err != nil {
+					t.Fatal(err)
+				}
+			}
+			if served, why := executeServedHere(statePath, row.heard); served != row.served {
+				t.Errorf("%s: served %v (%s)", row.name, served, why)
+			}
+		}
+	})
 }
 
 // A verdict waiting for the setuid search says how far it got, in the reason the root-free verb repeats and as

cmd/mesh-host/whatruns_test.go

@@ -4,6 +4,7 @@ import (
 	"crypto/ed25519"
 	"encoding/json"
 	"errors"
+	"path/filepath"
 	"strings"
 	"testing"
 
@@ -11,6 +12,7 @@ import (
 	"git.novox.be/novox/mesh-sdk/go/delivery"
 
 	"github.com/novox/mesh-host/internal/agent"
+	"github.com/novox/mesh-host/internal/store"
 )
 
 func aFileOf(module, id string) json.RawMessage {
@@ -59,6 +61,41 @@ func TestDeclaredNowReadsWhatRunsWhenTheAgentIsRunning(t *testing.T) {
 	if err != nil || d.Provisioner != "from-agent" {
 		t.Fatalf("declaredNow read %+v (%v), not what runs", d, err)
 	}
+
+	// L3 s9 (ADR 0550 §2): a node whose placed modules all have a have reads the kept declaration no more, though the
+	// file is there and readable and the controller's key is dropped; until then it reads it.
+	state := filepath.Join(t.TempDir(), "state", "state.json")
+	if err := store.SaveDeclared(store.DeclaredPath(state), store.Declared{Declaration: []byte(`{"declaration":1,` +
+		`"resources":[{"id":"zsh.rc","type":"file","module":"zsh","path":"/etc/zshrc","content":"x"}]}`)}); err != nil {
+		t.Fatal(err)
+	}
+	if d, err := keptDeclaration(state, nil); err != nil || len(d.Resources) != 1 {
+		t.Fatalf("before the read is retired: %+v, %v", d, err)
+	}
+	placed := delivery.Placement{Node: "n1", Modules: []delivery.PlacedModule{{Module: "zsh"}, {Module: "lemurs"}}}
+	for _, row := range []struct {
+		name string
+		has  map[string]bool
+		want bool
+	}{
+		{"every placed module has a have", map[string]bool{"zsh": true, "lemurs": true}, true},
+		{"one has none yet", map[string]bool{"zsh": true}, false},
+	} {
+		if got, why := allHave(placed, func(m string) (bool, error) { return row.has[m], nil }); got != row.want {
+			t.Errorf("%s: %v (%s)", row.name, got, why)
+		}
+	}
+	if got, _ := allHave(delivery.Placement{Node: "n1"}, nil); got {
+		t.Error("a node with nothing placed retires the read")
+	}
+	keptRetired.Store(true)
+	defer keptRetired.Store(false)
+	if _, err := keptDeclaration(state, nil); !errors.Is(err, errKeptRetired) {
+		t.Errorf("after the read is retired: %v", err)
+	}
+	if by, filled := keptOnce(options{state: state}, nil)(); by != nil || filled != nil {
+		t.Errorf("after the read is retired the kept declaration was split: %v %v", by, filled)
+	}
 }
 
 // 1945/AC17 (unit): a resource the node's own composition shares with a running module's composition is declared once,

go.mod

@@ -3,7 +3,7 @@ module github.com/novox/mesh-host
 go 1.26.0
 
 require (
-	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261028234900-c2999a4e13cc
+	git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261030001116-2da0de75c3f0
 	github.com/nats-io/nats-server/v2 v2.11.17
 	github.com/nats-io/nats.go v1.54.0
 	golang.org/x/crypto v0.57.0

go.sum

@@ -1,5 +1,5 @@
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261028234900-c2999a4e13cc h1:mOk2tAKTiuvnap/BUIYz91lLVbHi/EB6JPAD6KxTPvc=
-git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261028234900-c2999a4e13cc/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261030001116-2da0de75c3f0 h1:lKU3HjNXGiVbLW2hUgFjU/TMTUYMlNnnmZxG5T7biQA=
+git.novox.be/novox/mesh-sdk/go v0.1.14-0.20261030001116-2da0de75c3f0/go.mod h1:ouERNpZizzwZ0HLEtAypsY9FR20FyUgUYRni6J7kVCY=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op h1:Z/MZK75wC/NSrkgqeNIa7jexam9uWzhLmFTSCPI/kn0=
 github.com/antithesishq/antithesis-sdk-go v0.7.0-default-no-op/go.mod h1:FQyySiasQQM8735Ddel3MRojmy4dA1IqCeyJ5jmPMbI=
 github.com/google/go-tpm v0.9.8 h1:slArAR9Ft+1ybZu0lBwpSmpwhRXaa85hWtMinMyRAWo=

internal/accounts/setuid_cache.go

@@ -240,6 +240,17 @@ func (c *SetuidCache) SearchAgain() {
 	c.forgetProgress()
 }
 
+// Running says whether a search walks now (novox/hq ADR 0563 §2: the node seat starts no second while one does).
+// Nil c runs none.
+func (c *SetuidCache) Running() bool {
+	if c == nil {
+		return false
+	}
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.running
+}
+
 // SearchNow throws away the last complete search, kept or in memory, and any walk under way or kept, and has
 // the next look start a full search at once, past AgainAfter and any back-off (novox/hq issue 361): the
 // operator changed by hand what the last one found, which no apply says. Until the new one completes the

internal/agent/agent.go

@@ -109,7 +109,9 @@ type Env struct {
 	Kept func() map[string][]json.RawMessage
 	// KeptFilled is the paths the kept declaration names as filled by the provisioner, by the module whose file is at
 	// each (the node's own under NodeModule). A module that still runs from the kept declaration keeps its filled files
-	// filled: without them the filling refused each one as "not named as filled" (issue 1945). Nil names none.
+	// filled: without them the filling refused each one as "not named as filled" (issue 1945). Nil names none. A module
+	// whose have names a composition the bucket keeps runs from that composition, never from the kept declaration
+	// (issue 924): the kept declaration is older than every composition applied since the switch.
 	KeptFilled func() map[string][]string
 	// Trusted is the public keys a composition may be signed by: the controller's and the operator's (ADR 0539 §3). A
 	// composition unsigned, signed by another key, or changed after it was signed is refused and nothing of it is
@@ -131,6 +133,12 @@ type Env struct {
 	// them. The node-engine's filling tells the provisioner's client then to fill again what it refused (mesh-host
 	// internal/filling Knock; ace, 2026-10-25 21:17). Nil tells nothing.
 	Settled func(module string)
+	// RunsChanged is told, outside the agent's lock, that what runs (Everything) changed other than by an apply or a
+	// removal: once at the start, when the haves and the compositions they name are read, and each time a module is
+	// taken as running from its have or the kept declaration. Like Settled, the filling then tells the provisioner's
+	// client to fill again what it refused (issue 924, the second meeting: ace, g14 and shanks on 2026-10-29 at 00:09
+	// UTC refused power's three new drop-ins from an engine start on, as no module settled after it). Nil tells nothing.
+	RunsChanged func(why string)
 	// Backoff is how long to wait before the try-th retry (1, 2, …) of an apply that failed transiently. Nil retries a
 	// transient failure only on RetryTransient or a change of either key.
 	Backoff func(try int) time.Duration
@@ -143,6 +151,27 @@ type Env struct {
 	// move of a module of policy record that recreates a container or moves its data waits for a person's yes in its
 	// want (ADR 0547 §3). Nil judges no move.
 	Policy func(ctx context.Context, module string) string
+	// HoldsData says whether a module's manifest declares data (catalogue.Manifest.DataItems), and whether its manifest
+	// could be read: what a composition's Data is, for what runs of a module from the kept declaration, which carries no
+	// Data of its own. A composition says Data, so without it a data module from the kept declaration is judged to move
+	// its data against its first composition after a restart (mongodb and mssql on novox, issue 924). Nil reads none.
+	HoldsData func(ctx context.Context, module string) (data, known bool)
+	// Applied keeps every composition the agent applied, by module (the node's own under NodeModule), beside the engine's
+	// state on the machine: read at the start before anything is watched, so what runs is known before the node composes
+	// its own for the first time, whatever the bucket and the kept declaration still hold (issue 774: on 2026-10-29 the
+	// bus node, its kept declaration retired and its own composition in no bucket, composed its own as if its folded
+	// modules ran nothing and removed the bus server and four held modules). Nil keeps none.
+	Applied AppliedStore
+}
+
+// AppliedStore is where the engine keeps the compositions it applied (Env.Applied): each module's last, as its bytes.
+type AppliedStore interface {
+	// Load is every composition kept, by module; a store that cannot be read says so and loads none.
+	Load() (map[string][]byte, error)
+	// Keep keeps the composition the module was applied from, in place of the one before.
+	Keep(module string, raw []byte) error
+	// Drop forgets the module's, once it is removed.
+	Drop(module string) error
 }
 
 // transientFor is how many transient retries say the phase applying before the have says failed: past them the bus has
@@ -160,6 +189,13 @@ type Agent struct {
 	// applied is the composition each module was last applied from: a revision a want named from the key's history is
 	// not the key's latest value, and what it holds is still held out of the others' applies.
 	applied map[string]compNow
+	// had is, for each module whose have names a composition the bucket keeps (its latest value or a revision), that
+	// composition, read once at the start (loadHad): what runs of a module the agent has not taken yet, ahead of the kept
+	// declaration (issue 924).
+	had map[string]compNow
+	// keptData is, for each module of the kept declaration whose manifest could be read, whether it declares data
+	// (Env.HoldsData): the Data of what runs of it from the kept declaration.
+	keptData map[string]bool
 	// attempt is the last apply of a module that failed or is held, with the revisions it was made from.
 	attempt map[string]attempt
 	checked map[string]bool
@@ -218,7 +254,7 @@ func New(env Env) *Agent {
 	if env.Say == nil {
 		env.Say = func(string) {}
 	}
-	return &Agent{env: env, wants: map[string]wantNow{}, comps: map[string]compNow{}, running: map[string]delivery.Have{}, applied: map[string]compNow{},
+	return &Agent{env: env, wants: map[string]wantNow{}, comps: map[string]compNow{}, running: map[string]delivery.Have{}, applied: map[string]compNow{}, had: map[string]compNow{}, keptData: map[string]bool{},
 		attempt: map[string]attempt{}, checked: map[string]bool{}, prior: map[string]bool{}, said: map[string]string{}, notComposed: map[string]notComposedMark{},
 		retry: make(chan []string, 8), reconcile: make(chan []string, 64), tries: map[string]int{}, again: make(chan againAsk, 64),
 		transient: make(chan struct{}, 1), stopped: make(chan struct{})}
@@ -228,6 +264,9 @@ func New(env Env) *Agent {
 // before any module's, then each change as it comes.
 func (a *Agent) Run(ctx context.Context) error {
 	defer close(a.stopped)
+	// What this engine last applied, before any composition is watched: the node composing its own reads what runs
+	// (Everything) from its first pass on, and that pass comes before the haves are read below (issue 774).
+	a.loadApplied(ctx)
 	wants, err := a.env.Wants.Watch(ctx, "want."+a.env.Node+".>")
 	if err != nil {
 		return fmt.Errorf("the agent cannot watch its wants: %w", err)
@@ -236,7 +275,7 @@ func (a *Agent) Run(ctx context.Context) error {
 	if err != nil {
 		return fmt.Errorf("the agent cannot watch its compositions: %w", err)
 	}
-	var wantsCaught, compsCaught bool
+	var wantsCaught, compsCaught, hadRead bool
 	dirty := map[string]bool{}
 	for {
 		select {
@@ -303,7 +342,17 @@ func (a *Agent) Run(ctx context.Context) error {
 		}
 		// Nothing is applied until what was there at the start is all in: a module's composition may arrive after its
 		// want, and the node's own composition comes before any module's.
-		if !(wantsCaught && compsCaught) || len(dirty) == 0 {
+		if !(wantsCaught && compsCaught) {
+			continue
+		}
+		if !hadRead {
+			// Before the first settle: what runs of each module with a have, from the composition it names, so the
+			// filling judges by it at once and not by the kept declaration until some module settles (issue 924).
+			hadRead = true
+			a.loadHad(ctx)
+			a.runsChanged("the haves were read at the start")
+		}
+		if len(dirty) == 0 {
 			continue
 		}
 		a.settle(ctx, dirty)
@@ -726,7 +775,12 @@ func (a *Agent) revisionNamed(ctx context.Context, module, fp, digest string) (c
 		if err != nil {
 			continue
 		}
-		dig, err := delivery.VerifyComposed(c, trusted)
+		var dig string
+		if a.env.SelfComposed {
+			dig, err = delivery.ComposedDigestOf(c) // the node's own: unsigned (ADR 0547 §2)
+		} else {
+			dig, err = delivery.VerifyComposed(c, trusted)
+		}
 		if err != nil || dig != digest {
 			continue
 		}
@@ -755,22 +809,33 @@ func (a *Agent) others(except string) []delivery.Composed {
 			out = append(out, c.C)
 		} else if c, ok := a.applied[m]; ok && c.Dig == h.Composed {
 			out = append(out, c.C)
+		} else if c, ok := a.had[m]; ok && c.Dig == h.Composed {
+			out = append(out, c.C) // a revision its have named, replaced since under the same key
 		}
 	}
+	hadNames := make([]string, 0, len(a.had))
+	for m := range a.had {
+		if _, held := a.running[m]; !held && m != except {
+			hadNames = append(hadNames, m)
+		}
+	}
+	sort.Strings(hadNames)
+	for _, m := range hadNames {
+		out = append(out, a.had[m].C)
+	}
 	if a.env.Kept != nil {
 		kept := a.env.Kept()
 		names := make([]string, 0, len(kept))
 		for m := range kept {
-			if _, held := a.running[m]; !held && m != except {
+			_, held := a.running[m]
+			_, had := a.had[m]
+			if !held && !had && m != except {
 				names = append(names, m)
 			}
 		}
 		sort.Strings(names)
 		for _, m := range names {
-			c := delivery.Composed{Node: a.env.Node, Module: m, Resources: kept[m]}
-			if a.env.KeptFilled != nil {
-				c.Filled = a.env.KeptFilled()[m]
-			}
+			c, _ := a.keptComposed(m, kept[m])
 			if m == NodeModule {
 				c.Module = ""
 			}
@@ -780,6 +845,188 @@ func (a *Agent) others(except string) []delivery.Composed {
 	return out
 }
 
+// loadHad reads, once at the start, the have of every module with a want or in the kept declaration and, where it names
+// a composition, that composition: the bucket's value at its key when its digest is the have's, else the revision the
+// bucket keeps with that digest. A have naming none, or one the bucket no longer keeps, leaves the module to the kept
+// declaration, said once (issue 924).
+func (a *Agent) loadHad(ctx context.Context) {
+	a.mu.Lock()
+	seen := map[string]bool{}
+	for m, w := range a.wants {
+		if m != NodeModule && w.Present && !w.Want.Removed {
+			seen[m] = true
+		}
+	}
+	if a.env.Kept != nil {
+		for m := range a.env.Kept() {
+			if m != NodeModule {
+				seen[m] = true
+			}
+		}
+	}
+	a.mu.Unlock()
+	names := make([]string, 0, len(seen))
+	for m := range seen {
+		names = append(names, m)
+	}
+	sort.Strings(names)
+	a.readKeptData(ctx, names...)
+	for _, m := range names {
+		if ctx.Err() != nil {
+			return
+		}
+		h, ok := a.env.Haves.Read(ctx, m)
+		if !ok || h.Composed == "" || !haveRuns(h) {
+			continue
+		}
+		a.mu.Lock()
+		if c, kept := a.had[m]; kept && c.Dig == h.Composed {
+			a.mu.Unlock()
+			continue // what this engine applied and kept itself (loadApplied)
+		}
+		c, found := a.compositionFor(m, h.FP)
+		a.mu.Unlock()
+		if !found || c.Err != nil || c.Dig != h.Composed {
+			c, found = a.revisionNamed(ctx, m, h.FP, h.Composed)
+		}
+		a.mu.Lock()
+		if found {
+			a.had[m] = c
+		} else if _, applied := a.had[m]; applied {
+			// Kept as this engine applied it (loadApplied), never composed as nothing.
+		} else if _, kept := a.keptHas(m); kept {
+			a.sayOnce("had:"+m, fmt.Sprintf("%s's have names the composition %s, which the bucket no longer keeps: it runs "+
+				"from the kept declaration until it is applied or taken", m, short(h.Composed)))
+		}
+		a.mu.Unlock()
+	}
+}
+
+// loadApplied takes, once at the start, what this engine last applied of each module as what runs of it, ahead of the
+// bucket and the kept declaration (Env.Applied, issue 774): it is what the machine holds, whatever the bus still keeps.
+// One whose have names another composition runs as applied until loadHad reads that one from the bucket; one whose
+// have cannot be read, or that has none, is kept as applied, so a module is never composed as running nothing.
+func (a *Agent) loadApplied(ctx context.Context) {
+	if a.env.Applied == nil {
+		return
+	}
+	kept, err := a.env.Applied.Load()
+	if err != nil {
+		a.env.Say(fmt.Sprintf("the compositions this engine applied cannot be read, so what runs is read from the haves alone: %v", err))
+	}
+	// At an engine's first start nothing is kept yet: the node's own runs as the kept declaration has it, which the store
+	// keeps now, so the node never composes its own as if its folded modules ran nothing once the declaration retires
+	// (issue 774, review of the re-land, round 1). Taken whatever digest the node's have names: the composition that names
+	// is in no bucket, and the declaration is the one record of what runs on disk.
+	seeded := false
+	if _, own := kept[NodeModule]; !own && err == nil && a.env.Kept != nil {
+		if rs, ok := a.env.Kept()[NodeModule]; ok && len(rs) > 0 {
+			c, _ := a.keptComposed(NodeModule, rs)
+			c.Module = ""
+			raw, eerr := delivery.EncodeComposed(c)
+			if eerr == nil {
+				eerr = a.env.Applied.Keep(NodeModule, raw)
+			}
+			if eerr != nil {
+				a.env.Say(fmt.Sprintf("the node's own as the kept declaration has it cannot be kept: %v", eerr))
+			} else {
+				if kept == nil {
+					kept = map[string][]byte{}
+				}
+				kept[NodeModule], seeded = raw, true
+				a.env.Say("the node's own runs as the kept declaration has it, kept now as what this engine runs")
+			}
+		}
+	}
+	names := make([]string, 0, len(kept))
+	for m := range kept {
+		names = append(names, m)
+	}
+	sort.Strings(names)
+	for _, m := range names {
+		if ctx.Err() != nil {
+			return
+		}
+		c, err := delivery.DecodeComposed(kept[m])
+		var dig string
+		if err == nil {
+			dig, err = delivery.ComposedDigestOf(c)
+		}
+		if err != nil {
+			a.env.Say(fmt.Sprintf("the composition this engine kept of %s cannot be read, so what runs of it is read from its have: %v", m, err))
+			continue
+		}
+		h, found, unread := a.readHave(ctx, m)
+		if seeded && m == NodeModule {
+			found, unread = true, false // what the kept declaration has runs, whatever the have names
+		} else if found && h.Composed != "" && h.Composed != dig && haveRuns(h) {
+			// The composition the have names replaces this once loadHad finds it in the bucket; until then, and when
+			// the bucket keeps it no more, what this engine applied runs (issue 774, review of the re-land, round 1).
+			a.env.Say(fmt.Sprintf("%s's have names the composition %s, not %s this engine applied last: it runs as applied "+
+				"until the one its have names is read", m, short(h.Composed), short(dig)))
+		}
+		if m == NodeModule {
+			c.Module, c.FP = "", ""
+		}
+		a.mu.Lock()
+		a.had[m] = compNow{Raw: kept[m], C: c, Dig: dig}
+		a.mu.Unlock()
+		switch {
+		case unread:
+			a.env.Say(fmt.Sprintf("%s's have cannot be read: it runs as this engine applied it, %s", m, short(dig)))
+		case !found:
+			a.env.Say(fmt.Sprintf("%s has no have: it runs as this engine applied it, %s", m, short(dig)))
+		}
+	}
+}
+
+// keepApplied keeps the composition a module was applied from (Env.Applied); one that cannot be kept is said, and the
+// apply stands.
+func (a *Agent) keepApplied(module string, comp compNow) {
+	if a.env.Applied == nil {
+		return
+	}
+	raw := comp.Raw
+	if len(raw) == 0 {
+		var err error
+		if raw, err = delivery.EncodeComposed(comp.C); err != nil {
+			a.env.Say(fmt.Sprintf("the composition %s was applied from cannot be kept: %v", module, err))
+			return
+		}
+	}
+	if err := a.env.Applied.Keep(module, raw); err != nil {
+		a.env.Say(fmt.Sprintf("the composition %s was applied from cannot be kept: %v", module, err))
+	}
+}
+
+// haveRuns says a have names what runs, in the phases baseline takes as running: running (or empty), held for a failed
+// backup, or a composer's mark over what still runs. A have backing up, applying, checking, failed or waiting names a
+// composition not applied, or not yet (issue 924, review of 031e106).
+func haveRuns(h Have) bool {
+	switch delivery.Phase(h.Phase) {
+	case "", delivery.PhaseRunning, delivery.PhaseHeld:
+		return true
+	}
+	return composerMark(h)
+}
+
+// keptHas says whether the kept declaration has resources for the module. Called holding a.mu or not: Kept takes no lock
+// of the agent's.
+func (a *Agent) keptHas(module string) ([]json.RawMessage, bool) {
+	if a.env.Kept == nil {
+		return nil, false
+	}
+	rs, ok := a.env.Kept()[module]
+	return rs, ok
+}
+
+// runsChanged tells RunsChanged, outside the agent's lock.
+func (a *Agent) runsChanged(why string) {
+	if a.env.RunsChanged != nil {
+		a.env.RunsChanged(why)
+	}
+}
+
 // unreadableModules are the keys of the module compositions in the node's bucket that cannot be read or are refused, of a
 // module the assigner has not removed: for each module only the composition its want names, else its newest, since a
 // stale one nobody applies (written before a rule the SDK now holds) must not hold the node's own back. Called holding
@@ -901,7 +1148,8 @@ func (a *Agent) heldOut(except string) []delivery.Composed {
 			}
 		}
 		if len(rs) > 0 {
-			out = append(out, delivery.Composed{Node: a.env.Node, Module: m, Resources: rs})
+			// Held out, never judged: its Data from its manifest where known, as every other composition says it.
+			out = append(out, delivery.Composed{Node: a.env.Node, Module: m, Resources: rs, Data: a.keptData[m]})
 		}
 	}
 	return out
@@ -916,6 +1164,34 @@ func (a *Agent) Everything() []delivery.Composed {
 	return a.others("\x00")
 }
 
+// Placed is the modules a want still places on the node (present and not removed), held ones included, but except:
+// what no apply but the module's own may remove (apply.Scope.Placed, issue 774). Called without a.mu held.
+func (a *Agent) Placed(except string) map[string]bool {
+	a.mu.Lock()
+	defer a.mu.Unlock()
+	out := map[string]bool{}
+	for m, w := range a.wants {
+		if m != NodeModule && m != except && w.Present && !w.Want.Removed {
+			out[m] = true
+		}
+	}
+	return out
+}
+
+// RemovedByWant is the modules whose want says removed (apply.Scope.RemovedByWant, issue 774): in the node's own apply,
+// only their resources may go. Called without a.mu held.
+func (a *Agent) RemovedByWant() map[string]bool {
+	a.mu.Lock()
+	defer a.mu.Unlock()
+	out := map[string]bool{}
+	for m, w := range a.wants {
+		if m != NodeModule && w.Present && w.Want.Removed {
+			out[m] = true
+		}
+	}
+	return out
+}
+
 // HoldsNode says whether the agent runs the node's own composition, so the node's parts are its and not the kept
 // declaration's.
 func (a *Agent) HoldsNode() bool {
@@ -1048,6 +1324,7 @@ func (a *Agent) baseline(ctx context.Context, module string, w wantNow, comp com
 					a.running[module] = delivery.Have{FP: h.FP, Composed: h.Composed, Phase: delivery.PhaseRunning}
 				}
 				a.mu.Unlock()
+				a.runsChanged(module + " was taken as held")
 				return true
 			}
 			if h.Composed != "" {
@@ -1068,6 +1345,7 @@ func (a *Agent) baseline(ctx context.Context, module string, w wantNow, comp com
 					a.mu.Lock()
 					a.running[module] = delivery.Have{FP: h.FP, Composed: h.Composed, Phase: delivery.PhaseRunning}
 					a.mu.Unlock()
+					a.runsChanged(module + " was taken from its have")
 					// Said again, so the session holds the module and its key carries the health this engine judges,
 					// not the one an older engine left there (xorg's unknown on g14 and shanks, 2026-10-25).
 					a.writeHave(ctx, Have{Module: module, FP: h.FP, Composed: h.Composed,
@@ -1096,6 +1374,7 @@ func (a *Agent) baseline(ctx context.Context, module string, w wantNow, comp com
 	a.mu.Lock()
 	a.running[module] = delivery.Have{FP: w.Want.FP, Composed: w.Want.Composed, Phase: delivery.PhaseRunning}
 	a.mu.Unlock()
+	a.runsChanged(module + " was taken from the kept declaration")
 	a.writeHave(ctx, Have{Module: module, FP: w.Want.FP, Composed: w.Want.Composed, Phase: string(delivery.PhaseRunning)})
 	return true
 }
@@ -1184,6 +1463,7 @@ func (a *Agent) apply(ctx context.Context, module string, w wantNow, comp compNo
 	a.running[module] = delivery.Have{FP: fp, Composed: dig, Phase: delivery.PhaseRunning}
 	a.applied[module] = comp
 	a.mu.Unlock()
+	a.keepApplied(module, comp)
 	if a.env.Settled != nil {
 		a.env.Settled(module)
 	}
@@ -1213,8 +1493,14 @@ func (a *Agent) remove(ctx context.Context, module string, w wantNow) {
 		return
 	}
 	delete(a.attempt, module)
+	delete(a.had, module)
 	a.running[module] = delivery.Have{Phase: delivery.PhaseRemoved}
 	a.mu.Unlock()
+	if a.env.Applied != nil {
+		if err := a.env.Applied.Drop(module); err != nil {
+			a.env.Say(fmt.Sprintf("the composition %s was applied from cannot be forgotten now it is removed: %v", module, err))
+		}
+	}
 	if a.env.Settled != nil {
 		a.env.Settled(module)
 	}
@@ -1286,6 +1572,7 @@ func (a *Agent) waitsForYes(ctx context.Context, module string, w wantNow, comp
 	if module == NodeModule || a.env.Policy == nil || a.env.Policy(ctx, module) != catalogue.PolicyRecord || w.Want.Yes == comp.Dig {
 		return false
 	}
+	a.readKeptData(ctx, module) // the manifest may read now though it did not at the start
 	a.mu.Lock()
 	r, ran := a.running[module]
 	if ran && r.Composed == comp.Dig && r.Phase != delivery.PhaseRemoved {
@@ -1331,14 +1618,61 @@ func (a *Agent) waitsForYes(ctx context.Context, module string, w wantNow, comp
 
 // runningComposition is what the module runs now: the composition last applied, else its resources in the declaration
 // the node kept from before the switch. Called with a.mu held.
+//
+// The composition its have named at the start comes before the kept declaration (issue 924). From the kept declaration,
+// what runs carries Data as its manifest declares it; a module whose manifest could not be read cannot be judged against
+// it (false), and that is said, rather than taking it to hold no data and judging a false move of its data.
 func (a *Agent) runningComposition(module string) (delivery.Composed, bool) {
 	if c, ok := a.applied[module]; ok && c.Err == nil {
 		return c.C, true
 	}
-	if a.env.Kept != nil {
-		if rs, ok := a.env.Kept()[module]; ok {
-			return delivery.Composed{Node: a.env.Node, Module: module, Resources: rs}, true
+	if c, ok := a.had[module]; ok {
+		return c.C, true
+	}
+	if rs, ok := a.keptHas(module); ok {
+		c, known := a.keptComposed(module, rs)
+		if !known {
+			a.sayOnce("kept-data:"+module, fmt.Sprintf("%s runs from the kept declaration, and whether it holds data cannot be "+
+				"read from its manifest: a move of it cannot be judged", module))
 		}
+		return c, known
 	}
 	return delivery.Composed{}, false
 }
+
+// keptComposed is what runs of a module from the kept declaration: its resources there, the paths it names as filled,
+// and Data as the module's manifest declares it; false when the manifest could not be read, so Data is not known. Called
+// with a.mu held.
+func (a *Agent) keptComposed(module string, rs []json.RawMessage) (delivery.Composed, bool) {
+	c := delivery.Composed{Node: a.env.Node, Module: module, Resources: rs}
+	if a.env.KeptFilled != nil {
+		c.Filled = a.env.KeptFilled()[module]
+	}
+	data, known := a.keptData[module]
+	c.Data = data
+	return c, known || module == NodeModule
+}
+
+// readKeptData reads, outside the agent's lock, whether each module of the kept declaration not known yet declares data
+// (Env.HoldsData), and keeps the answers it could read.
+func (a *Agent) readKeptData(ctx context.Context, modules ...string) {
+	if a.env.HoldsData == nil {
+		return
+	}
+	for _, m := range modules {
+		if m == NodeModule {
+			continue
+		}
+		a.mu.Lock()
+		_, done := a.keptData[m]
+		a.mu.Unlock()
+		if _, kept := a.keptHas(m); done || !kept {
+			continue
+		}
+		if data, known := a.env.HoldsData(ctx, m); known {
+			a.mu.Lock()
+			a.keptData[m] = data
+			a.mu.Unlock()
+		}
+	}
+}

internal/agent/agent_test.go

@@ -769,6 +769,162 @@ func TestEverythingIsWhatTheAgentRunsAndWhatIsKeptForTheRest(t *testing.T) {
 	if a.HoldsNode() {
 		t.Fatal("the agent holds no node composition")
 	}
+
+	// Issue 774 (novox, 2026-10-29 07:54 UTC): the kept declaration retired and the node's own composition in no bucket, a
+	// fresh engine's first own composition was composed from what runs with the node's own missing, so its folded modules
+	// (the bus server among them) were composed as nothing and removed. What this engine applied is kept on the machine
+	// and is what runs from before the first composition is watched; an apply keeps, a removal forgets.
+	t.Run("what this engine applied is what runs before the node composes its own", func(t *testing.T) {
+		b := newBed(t)
+		b.env.SelfComposed, b.env.Trusted, b.kept = true, nil, nil
+		store := &memApplied{kept: map[string][]byte{}}
+		b.env.Applied = store
+		// A folded module's resource in the node's own composition: its id names the module, as the controller folds it.
+		natsConf, _ := json.Marshal(map[string]any{"id": "nats.conf", "type": "file", "path": "/tmp/r6/nats/conf", "content": "listen 4222"})
+		own := delivery.Composed{Node: node, Resources: []json.RawMessage{natsConf}}
+		ownRaw, err := delivery.EncodeComposed(own)
+		if err != nil {
+			t.Fatal(err)
+		}
+		ownDig, _ := delivery.ComposedDigestOf(own)
+		web := delivery.Composed{Node: node, Module: "web", FP: fpOf("a"), Resources: []json.RawMessage{file("web", "x", "1")}}
+		webRaw, _ := delivery.EncodeComposed(web)
+		webDig, _ := delivery.ComposedDigestOf(web)
+		store.kept[NodeModule], store.kept["web"] = ownRaw, webRaw
+		b.haves.Write(context.Background(), Have{Module: NodeModule, Composed: ownDig})
+		b.haves.Write(context.Background(), Have{Module: "web", FP: fpOf("a"), Composed: webDig, Phase: string(delivery.PhaseRunning)})
+		// The composer's first pass reads what runs when its watch begins, before the agent reads any have.
+		firstCh := make(chan []delivery.Composed, 1)
+		comps := b.comps
+		var ag *Agent
+		b.env.Composed = watchFunc(func(ctx context.Context, p string) (<-chan Update, error) {
+			firstCh <- ag.Everything()
+			return comps.Watch(ctx, p)
+		})
+		ag = New(b.env)
+		b.ag = ag
+		ctx, cancel := context.WithCancel(context.Background())
+		done := make(chan struct{})
+		go func() { defer close(done); _ = ag.Run(ctx) }()
+		defer func() { cancel(); <-done }()
+		var first []delivery.Composed
+		select {
+		case first = <-firstCh:
+		case <-time.After(5 * time.Second):
+			t.Fatal("the composer was not watched")
+		}
+		var ranOwn, ranWeb bool
+		for _, c := range first {
+			ranOwn = ranOwn || (c.Module == "" && len(c.Resources) == 1 && strings.Contains(string(c.Resources[0]), "4222"))
+			ranWeb = ranWeb || c.Module == "web"
+		}
+		if !ranOwn || !ranWeb {
+			t.Fatalf("what runs at the node's first own composition: own %v, web %v (%d compositions); want both as this engine applied them",
+				ranOwn, ranWeb, len(first))
+		}
+		// An apply keeps the composition it applied; a removal forgets it.
+		web2 := delivery.Composed{Node: node, Module: "web", FP: fpOf("b"), Resources: []json.RawMessage{file("web", "x", "2")}}
+		ck, _ := delivery.ComposedKey(node, "web", fpOf("b"))
+		raw2, _ := delivery.EncodeComposed(web2)
+		comps.put(ck, raw2)
+		wk, _ := delivery.WantKey(node, "web")
+		wraw, _ := delivery.EncodeWant(delivery.Want{FP: fpOf("b"), Self: true})
+		b.wants.put(wk, wraw)
+		eventually(t, "the applied composition was not kept", func() bool { return string(store.get("web")) == string(raw2) })
+		rraw, _ := delivery.EncodeWant(delivery.Want{Removed: true})
+		b.wants.put(wk, rraw)
+		eventually(t, "the removed module's composition was not forgotten", func() bool { return store.get("web") == nil })
+	})
+
+	// Issue 774, review of the re-land, round 1: at the re-landed engine's first start nothing is kept yet, and the node's
+	// have names a composition the node composed itself, in no bucket. The node's own runs as the kept declaration has it
+	// and is kept then, so the next start, the declaration retired, still runs nats.
+	t.Run("at the first start nothing is kept: the node's own runs as the kept declaration has it", func(t *testing.T) {
+		natsConf, _ := json.Marshal(map[string]any{"id": "nats.conf", "type": "file", "path": "/tmp/r6/nats/conf", "content": "listen 4222"})
+		store := &memApplied{kept: map[string][]byte{}}
+		h := &haves{}
+		h.Write(context.Background(), Have{Module: NodeModule, Composed: "sha256:" + strings.Repeat("c", 64)})
+		firstPass := func(kept map[string][]json.RawMessage) []delivery.Composed {
+			b := newBed(t)
+			b.env.SelfComposed, b.env.Trusted, b.kept, b.env.Applied, b.env.Haves = true, nil, kept, store, h
+			firstCh := make(chan []delivery.Composed, 1)
+			comps := b.comps
+			var ag *Agent
+			b.env.Composed = watchFunc(func(ctx context.Context, p string) (<-chan Update, error) {
+				firstCh <- ag.Everything()
+				return comps.Watch(ctx, p)
+			})
+			ag = New(b.env)
+			ctx, cancel := context.WithCancel(context.Background())
+			done := make(chan struct{})
+			go func() { defer close(done); _ = ag.Run(ctx) }()
+			defer func() { cancel(); <-done }()
+			select {
+			case got := <-firstCh:
+				return got
+			case <-time.After(5 * time.Second):
+				t.Fatal("the composer was not watched")
+			}
+			return nil
+		}
+		runsNats := func(cs []delivery.Composed) bool {
+			for _, c := range cs {
+				if c.Module == "" && len(c.Resources) == 1 && strings.Contains(string(c.Resources[0]), "4222") {
+					return true
+				}
+			}
+			return false
+		}
+		if got := firstPass(map[string][]json.RawMessage{NodeModule: {natsConf}}); !runsNats(got) {
+			t.Fatalf("the first start does not run nats in the node's own (%d compositions)", len(got))
+		}
+		if store.get(NodeModule) == nil {
+			t.Fatal("the first start kept no node's own composition")
+		}
+		if got := firstPass(nil); !runsNats(got) {
+			t.Fatalf("the next start, the kept declaration retired, does not run nats in the node's own (%d compositions)", len(got))
+		}
+	})
+}
+
+// watchFunc is a Watcher from a function.
+type watchFunc func(ctx context.Context, pattern string) (<-chan Update, error)
+
+func (f watchFunc) Watch(ctx context.Context, pattern string) (<-chan Update, error) {
+	return f(ctx, pattern)
+}
+
+// memApplied is an AppliedStore in memory.
+type memApplied struct {
+	mu   sync.Mutex
+	kept map[string][]byte
+}
+
+func (m *memApplied) Load() (map[string][]byte, error) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	out := map[string][]byte{}
+	for k, v := range m.kept {
+		out[k] = v
+	}
+	return out, nil
+}
+func (m *memApplied) Keep(module string, raw []byte) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	m.kept[module] = raw
+	return nil
+}
+func (m *memApplied) Drop(module string) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	delete(m.kept, module)
+	return nil
+}
+func (m *memApplied) get(module string) []byte {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	return m.kept[module]
 }
 
 // A failed apply is applied again after a restart even when the kept declaration holds the composition: once this
@@ -1026,18 +1182,102 @@ func TestTheRevisionAWantNamesIsAppliedFromHistory(t *testing.T) {
 	}
 }
 
-// 1945/AC18 (unit): a module that still runs from the kept declaration carries the kept declaration's filled paths of
-// its files, so the filling writes them ("not named as filled" for claude-code and screen-lock, 2026-10-25).
-func TestAModuleRunningFromTheKeptDeclarationKeepsItsFilledPaths(t *testing.T) {
-	b := newBed(t)
-	b.kept = map[string][]json.RawMessage{"claude-code": {file("claude-code", "settings", "")}}
-	b.env.KeptFilled = func() map[string][]string {
-		return map[string][]string{"claude-code": {"/tmp/r6/claude-code/settings"}}
+// 1945/AC18 and issue 924 (unit): what runs of a module the agent has not taken yet carries the filled paths the
+// filling judges by. From the kept declaration while the module has no have naming a composition ("not named as filled"
+// for claude-code and screen-lock, 2026-10-25); from the composition its have names once it has one, the kept
+// declaration being older, read at the start before any module settles and told to the filling then, so a file the
+// newer composition fills is accepted on the first fill (power's three drop-ins on ace, g14 and shanks, 2026-10-29).
+// Only a have in a phase baseline takes as running names what runs; and what runs carries Data, from the composition
+// or, from the kept declaration, from the module's manifest, so a data module is not judged to move its data against
+// its first composition after a restart (mongodb and mssql on novox).
+func TestWhatRunsBeforeTheAgentTakesAModuleNamesItsFilledPaths(t *testing.T) {
+	const old, added = "/tmp/r6/power/settings", "/tmp/r6/power/bound"
+	filledFile := func(id string) json.RawMessage {
+		return json.RawMessage(`{"id":"power.` + id + `","type":"file","module":"power","path":"/tmp/r6/power/` + id +
+			`","mode":"0644","owner-at-runtime":"owned"}`)
 	}
-	a := New(b.env)
-	got := a.Everything()
-	if len(got) != 1 || got[0].Module != "claude-code" || strings.Join(got[0].Filled, ",") != "/tmp/r6/claude-code/settings" {
-		t.Fatalf("what runs from the kept declaration: %+v", got)
+	fp := fpOf("a")
+	ck, _ := delivery.ComposedKey(node, "power", fp)
+	applied := delivery.Composed{Node: node, Module: "power", FP: fp, Filled: []string{old, added}, Data: true,
+		Resources: []json.RawMessage{filledFile("settings"), filledFile("bound")}}
+	_, appliedRaw, appliedDig := signedBy(t, applied, ck, controllerKey)
+	newer := applied
+	newer.Resources = append([]json.RawMessage{}, applied.Resources...)
+	newer.Resources = append(newer.Resources, file("power", "later", "1"))
+	_, newerRaw, _ := signedBy(t, newer, ck, controllerKey)
+	for _, tc := range []struct {
+		name string
+		// have is the module's have; bucket the value its composition key holds now, history the revisions kept.
+		have         *Have
+		bucket       []byte
+		history      []Update
+		filled, told string
+		// data is what runs' Data; holdsData the manifest's answer (nil: none read).
+		data      bool
+		holdsData func(context.Context, string) (bool, bool)
+	}{
+		{name: "no have: the kept declaration's", filled: old},
+		{name: "a have naming the bucket's value", have: &Have{Module: "power", FP: fp, Composed: appliedDig},
+			bucket: appliedRaw, filled: old + "," + added, told: "the haves were read at the start", data: true},
+		{name: "a have applying names nothing that runs yet", have: &Have{Module: "power", FP: fp, Composed: appliedDig,
+			Phase: string(delivery.PhaseApplying)}, bucket: appliedRaw, filled: old, told: "the haves were read at the start"},
+		{name: "a data module from the kept declaration says Data as its manifest does", filled: old,
+			told: "the haves were read at the start", data: true,
+			holdsData: func(context.Context, string) (bool, bool) { return true, true }},
+		{name: "a have naming a revision replaced since", have: &Have{Module: "power", FP: fp, Composed: appliedDig},
+			bucket: newerRaw, history: []Update{{Key: ck, Value: appliedRaw, Revision: 3}, {Key: ck, Value: newerRaw, Revision: 7}},
+			filled: old + "," + added, told: "the haves were read at the start", data: true},
+		{name: "a have naming a composition the bucket no longer keeps", have: &Have{Module: "power", FP: fp, Composed: appliedDig},
+			bucket: newerRaw, filled: old, told: "the haves were read at the start"},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			b := newBed(t)
+			b.kept = map[string][]json.RawMessage{"power": {filledFile("settings")}}
+			b.env.KeptFilled = func() map[string][]string { return map[string][]string{"power": {old}} }
+			if tc.have != nil {
+				b.haves.stored = map[string]Have{"power": *tc.have}
+			}
+			if tc.bucket != nil {
+				b.comps.before(ck, tc.bucket)
+			}
+			b.env.Revisions = func(_ context.Context, key string) ([]Update, error) { return tc.history, nil }
+			b.env.HoldsData = tc.holdsData
+			var told []string
+			var mu sync.Mutex
+			b.env.RunsChanged = func(why string) { mu.Lock(); told = append(told, why); mu.Unlock() }
+			filledNow := func() string {
+				for _, c := range b.ag.Everything() {
+					if c.Module == "power" {
+						if c.Data != tc.data {
+							t.Errorf("what runs says Data %v, want %v", c.Data, tc.data)
+						}
+						return strings.Join(c.Filled, ",")
+					}
+				}
+				return ""
+			}
+			if tc.told == "" { // no want, no have: nothing to start, and the kept declaration is what runs
+				a := New(b.env)
+				b.ag = a
+				if got := filledNow(); got != tc.filled {
+					t.Fatalf("filled %q, want %q", got, tc.filled)
+				}
+				return
+			}
+			stop := b.run()
+			defer stop()
+			eventually(t, "the filling was not told what runs at the start", func() bool {
+				mu.Lock()
+				defer mu.Unlock()
+				return len(told) > 0 && told[0] == tc.told
+			})
+			if got := filledNow(); got != tc.filled {
+				t.Fatalf("filled %q, want %q", got, tc.filled)
+			}
+			if got := b.appliedList(); len(got) != 0 {
+				t.Fatalf("applied %v: nothing has a want", got)
+			}
+		})
 	}
 }
 

internal/apply/apply.go

@@ -312,6 +312,38 @@ type Scope struct {
 	Module string
 	// Others are the resources of every other module the node has a composition for.
 	Others []declaration.Resource
+	// Placed are the modules a want still places on the node (present, not removed), held ones included: no apply but
+	// the module's own removes a resource of one of them (issue 774: on 2026-10-29 the node's own apply on the bus node,
+	// composed without what its folded modules ran, removed the bus server and four held modules). Nil guards nothing.
+	Placed map[string]bool
+	// RemovedByWant are the modules whose want says removed. In the node's own apply (Module NodeModule) with this set
+	// non-nil, a resource of any other module is removed only when that module is here: a module the node runs folded
+	// in its own composition has no want, so Placed does not name it (issue 774, review of the re-land, round 1: nats on
+	// the bus node has none, and its nats.conf was guessed as nats's and removed). Nil guards by Placed alone.
+	RemovedByWant map[string]bool
+}
+
+// placedOwner is the module a want still places on the node that the record belongs to, other than the scope's own:
+// the module recorded with it, else the one its id names (a resource the node's own composition carried for a folded
+// module is recorded as the node's, its id naming the module). Empty when there is none.
+func (sc *Scope) placedOwner(a store.Applied) string {
+	if sc == nil || (len(sc.Placed) == 0 && sc.RemovedByWant == nil) {
+		return ""
+	}
+	m := a.Module
+	if m == "" || m == store.NodeModule {
+		m, _ = declaration.ModuleGuess(a.ID)
+	}
+	if m == "" || m == sc.Module || m == store.NodeModule {
+		return ""
+	}
+	if sc.Placed[m] {
+		return m
+	}
+	if sc.Module == store.NodeModule && sc.RemovedByWant != nil && !sc.RemovedByWant[m] {
+		return m // a module the node's own composition carried, which no want removed
+	}
+	return ""
 }
 
 // owns reports whether a record belongs to the scope's module.
@@ -441,6 +473,31 @@ func applyScoped(
 		}
 	}
 
+	// **A module a want still places here is never removed by another's apply** (issue 774): its resources go only with
+	// its own apply or its want's removal. One that would is refused whole, before anything is changed, naming them: a
+	// composition that leaves them out lost what runs, and removing what runs is the worst a node can do with that.
+	if scope != nil {
+		var refused []string
+		for _, orphan := range known.Orphans(declared, origin) {
+			if !scope.owns(orphan) {
+				continue
+			}
+			if _, kept := heldByOthers[orphan.ID]; kept {
+				continue
+			}
+			if m := scope.placedOwner(orphan); m != "" {
+				refused = append(refused, orphan.ID+" of "+m)
+			}
+		}
+		if len(refused) > 0 {
+			sort.Strings(refused)
+			err := fmt.Errorf("the apply of %s would remove %s, of modules a want still places here; a module's resources "+
+				"go only with its own apply or its want's removal, so nothing was applied", scope.Module, strings.Join(refused, ", "))
+			log("  refused: " + err.Error())
+			return report, known, &Error{Resource: "the resources of modules placed here", Err: err, Done: report}
+		}
+	}
+
 	removeOrphan := func(orphan store.Applied) error {
 		var action, detail string
 		var err error

internal/apply/filled.go

@@ -45,6 +45,30 @@ func WriteFilled(
 	log func(string),
 	keep Keep,
 	windows *Windows,
+) (report Report, _ store.State, _ error) {
+	return WriteFilledWith(ctx, sys, d, known, path, content, run, log, keep, windows, Filled{})
+}
+
+// Filled is what the node-engine did to a filled file's content before its write.
+type Filled struct {
+	// Secret says the node-engine filled a value into the content, a provision's `${secret:}` (novox/hq ADR 0570
+	// clause 6): the file is then written 0600 when the declaration gives no mode, as a file carrying a secret is.
+	Secret bool
+}
+
+// WriteFilledWith is WriteFilled for content the node-engine filled before the write (Filled).
+func WriteFilledWith(
+	ctx context.Context,
+	sys system.System,
+	d *declaration.Declaration,
+	known store.State,
+	path string,
+	content []byte,
+	run Runner,
+	log func(string),
+	keep Keep,
+	windows *Windows,
+	filled Filled,
 ) (report Report, _ store.State, _ error) {
 	if log == nil {
 		log = func(string) {}
@@ -65,7 +89,7 @@ func WriteFilled(
 		return report, known, &Error{Resource: path, Err: fmt.Errorf("%d resources declare %s, and a filled file "+
 			"is written for exactly one, so nothing was written", len(declared), path)}
 	}
-	file := filledAs(declared[0], content)
+	file := filledAs(declared[0], content, filled.Secret)
 	if held, isHeld := known.HeldAt(file.ID); isHeld {
 		return report, known, &Error{Resource: file.ID, Err: fmt.Errorf("%s is held as found for a module not "+
 			"yet taken (%s), so nothing was written", path, held.Why)}
@@ -163,10 +187,10 @@ func WriteFilled(
 }
 
 // filledAs is the declared file with the filled content in place of the declaration's.
-func filledAs(declared *declaration.File, content []byte) *declaration.File {
+func filledAs(declared *declaration.File, content []byte, secret bool) *declaration.File {
 	f := *declared
 	f.Content, f.Sealed, f.VaultSealed, f.Bytes, f.Secrets = string(content), "", nil, "", nil
-	if f.Mode == "" && (declared.Secret() || len(declared.Secrets) > 0) {
+	if f.Mode == "" && (secret || declared.Secret() || len(declared.Secrets) > 0) {
 		// Written as the declaration would have written it: a file carrying a credential is not world-readable.
 		f.Mode = "0600"
 	}

internal/apply/module_scope_test.go

@@ -3,6 +3,7 @@ package apply
 import (
 	"context"
 	"path/filepath"
+	"strings"
 	"testing"
 
 	"git.novox.be/novox/mesh-sdk/go/declaration"
@@ -116,32 +117,78 @@ func TestARecordWithoutAnOwnerBelongsToTheModuleItsIdNames(t *testing.T) {
 // leaves it as it is, whatever its type, until the module's own apply takes it (issue 1945, live on 2026-10-25 at 02:32:
 // shanks and g14 lost systemd-resolved's guard, its resolver files and sudo's operator file, ace qbittorrent's server,
 // because the node's own apply removed every record no longer in it, the others holding the very same resources or not).
+//
+// And a resource the node's own composition carried for a module a want still places here (a folded module of the old
+// form, held) is never removed by the node's own apply when a composition leaves it out: the apply is refused whole and
+// says why (issue 774, live on 2026-10-29 at 07:54 UTC on the bus node: the node's own composition, composed without what
+// it ran once the kept declaration was read no more, removed the bus server, the proxy and three held modules). Only its
+// want's removal lets it go.
 func TestAResourceThatMovedToItsModulesCompositionIsLeftByTheNodesOwnApply(t *testing.T) {
-	dir := t.TempDir()
-	fact := filepath.Join(dir, "suffix")
-	gone := filepath.Join(dir, "gone.conf")
-	own := declare(t, `{"id":"systemd-resolved.fact-suffix","type":"file","path":"`+fact+`","content":"mesh\n"},
-	  {"id":"old.gone","type":"file","path":"`+gone+`","content":"g\n"}`)
-	_, state, err := ApplyModule(context.Background(), archHost(t), own, Scope{Module: store.NodeModule},
-		state0(), store.OriginDeclared, noServices, nil, nil, nil, nil)
-	if err != nil {
-		t.Fatal(err)
-	}
-	// systemd-resolved now has a composition of its own, not applied yet; old.gone is no module's any more.
-	moved := declare(t, `{"id":"systemd-resolved.fact-suffix","type":"file","path":"`+fact+`","content":"mesh\n","module":"systemd-resolved"}`)
-	report, state, err := ApplyModule(context.Background(), archHost(t), &declaration.Declaration{},
-		Scope{Module: store.NodeModule, Others: moved.Resources}, state, store.OriginDeclared, noServices, nil, nil, nil, nil)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if !exists(fact) {
-		t.Fatalf("the moved resource was removed: %+v", outcomeOf(report, "systemd-resolved.fact-suffix"))
-	}
-	if exists(gone) {
-		t.Fatal("a resource no composition holds any more was kept")
-	}
-	if _, still := state.Find("systemd-resolved.fact-suffix"); !still {
-		t.Fatal("the moved resource's record was dropped, so its module's apply would not know it")
+	for _, tc := range []struct {
+		name    string
+		id      string // the resource the node's own composition carried, and no longer does
+		moved   bool   // its module's own composition now declares it (Others)
+		placed  bool   // a want still places its module here
+		refused bool   // the node's own apply is refused whole
+		stays   bool   // the resource is still on the machine and recorded
+		// wants names the modules whose want says removed (Scope.RemovedByWant); nil leaves the guard to Placed alone.
+		wants []string
+	}{
+		{name: "moved to its module's own composition", id: "systemd-resolved.fact-suffix", moved: true, placed: true, stays: true},
+		{name: "a held folded module, in no composition", id: "nats.server-conf", placed: true, refused: true, stays: true},
+		{name: "its module's want removed", id: "nats.server-conf"},
+		// Issue 774, review of the re-land, round 1: a module folded in the node's own has no want, so Placed does not name
+		// it; in the node's own apply only a module a want removed loses its resources.
+		{name: "a folded module with no want", id: "nats.server-conf", wants: []string{}, refused: true, stays: true},
+		{name: "a folded module a want removed", id: "nats.server-conf", wants: []string{"nats", "old"}},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			dir := t.TempDir()
+			fact := filepath.Join(dir, "carried")
+			gone := filepath.Join(dir, "gone.conf")
+			own := declare(t, `{"id":"`+tc.id+`","type":"file","path":"`+fact+`","content":"mesh\n"},
+			  {"id":"old.gone","type":"file","path":"`+gone+`","content":"g\n"}`)
+			_, state, err := ApplyModule(context.Background(), archHost(t), own, Scope{Module: store.NodeModule},
+				state0(), store.OriginDeclared, noServices, nil, nil, nil, nil)
+			if err != nil {
+				t.Fatal(err)
+			}
+			module, _ := declaration.ModuleGuess(tc.id)
+			scope := Scope{Module: store.NodeModule}
+			if tc.moved {
+				moved := declare(t, `{"id":"`+tc.id+`","type":"file","path":"`+fact+`","content":"mesh\n","module":"`+module+`"}`)
+				scope.Others = moved.Resources
+			}
+			if tc.placed {
+				scope.Placed = map[string]bool{module: true}
+			}
+			if tc.wants != nil {
+				scope.RemovedByWant = map[string]bool{}
+				for _, m := range tc.wants {
+					scope.RemovedByWant[m] = true
+				}
+			}
+			report, after, err := ApplyModule(context.Background(), archHost(t), &declaration.Declaration{}, scope, state,
+				store.OriginDeclared, noServices, nil, nil, nil, nil)
+			if tc.refused != (err != nil) {
+				t.Fatalf("refused %v, want %v: %v", err != nil, tc.refused, err)
+			}
+			if tc.refused {
+				if !strings.Contains(err.Error(), tc.id+" of "+module) {
+					t.Fatalf("the refusal does not name what it kept: %v", err)
+				}
+				after = state
+			}
+			if exists(fact) != tc.stays {
+				t.Fatalf("the carried resource exists %v, want %v: %+v", exists(fact), tc.stays, outcomeOf(report, tc.id))
+			}
+			if _, still := after.Find(tc.id); still != tc.stays {
+				t.Fatalf("the carried resource's record kept %v, want %v", still, tc.stays)
+			}
+			if exists(gone) == !tc.refused {
+				t.Fatalf("a resource no composition holds any more exists %v, with the apply refused %v", exists(gone), tc.refused)
+			}
+		})
 	}
 }
 

internal/apply/objectkeep.go

@@ -0,0 +1,111 @@
+package apply
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"time"
+
+	"git.novox.be/novox/mesh-sdk/go/declaration"
+)
+
+// ObjectKeep is the node-engine's own keep of the content of files given by digest (novox/hq ADR 0486 §1, issue 924): one
+// file per object, named as the object is, beside the node's state. **What a node once had it never asks the bus for
+// again**, so neither the controller's sweep of the bucket (an object is removed a day after no composition of the
+// controller names it) nor a bus that does not answer can refuse a composition the node already ran. The node's account
+// may only read its bucket (ADR 0486 §2), so the keep is the node's, not the bucket's: nothing is written back.
+//
+// An object unused for KeptObjectsFor is let go when another is kept, so the keep holds what the node applied lately and
+// not every export it ever ran. Every failure to keep is silent and costs only a fetch: the keep is a copy.
+type ObjectKeep struct {
+	Dir string
+	// Now is the clock; nil is time.Now.
+	Now func() time.Time
+}
+
+// KeptObjectsFor is how long an object of the keep is held after it was last used.
+const KeptObjectsFor = 14 * 24 * time.Hour
+
+// KeepObjectsIn is the keep at dir; an empty dir keeps nothing.
+func KeepObjectsIn(dir string) *ObjectKeep {
+	if dir == "" {
+		return nil
+	}
+	return &ObjectKeep{Dir: dir}
+}
+
+func (k *ObjectKeep) now() time.Time {
+	if k.Now != nil {
+		return k.Now()
+	}
+	return time.Now()
+}
+
+// get is the kept content of the object name when it is what f names, and marks it used.
+func (k *ObjectKeep) get(name string, f *declaration.File) ([]byte, bool) {
+	if k == nil {
+		return nil, false
+	}
+	path := filepath.Join(k.Dir, name)
+	body, err := os.ReadFile(path)
+	if err != nil || int64(len(body)) != f.Size || f.Verify(body) != nil {
+		return nil, false
+	}
+	now := k.now()
+	_ = os.Chtimes(path, now, now)
+	return body, true
+}
+
+// put keeps body under name, unless it is kept already (then it is marked used), and lets go of what was unused too long.
+func (k *ObjectKeep) put(name string, body []byte) {
+	if k == nil {
+		return
+	}
+	path := filepath.Join(k.Dir, name)
+	now := k.now()
+	if info, err := os.Stat(path); err == nil && info.Size() == int64(len(body)) {
+		_ = os.Chtimes(path, now, now)
+		return
+	}
+	if err := os.MkdirAll(k.Dir, 0o700); err != nil {
+		return
+	}
+	tmp, err := os.CreateTemp(k.Dir, ".put-*")
+	if err != nil {
+		return
+	}
+	_, werr := tmp.Write(body)
+	cerr := tmp.Close()
+	if werr != nil || cerr != nil || os.Chmod(tmp.Name(), 0o600) != nil || os.Rename(tmp.Name(), path) != nil {
+		_ = os.Remove(tmp.Name())
+		return
+	}
+	_ = os.Chtimes(path, now, now)
+	k.prune(now)
+}
+
+// prune lets go of every object unused for KeptObjectsFor.
+func (k *ObjectKeep) prune(now time.Time) {
+	entries, err := os.ReadDir(k.Dir)
+	if err != nil {
+		return
+	}
+	for _, e := range entries {
+		info, err := e.Info()
+		if err != nil || !info.Mode().IsRegular() {
+			continue
+		}
+		if now.Sub(info.ModTime()) >= KeptObjectsFor {
+			_ = os.Remove(filepath.Join(k.Dir, e.Name()))
+		}
+	}
+}
+
+// never says, in a failed fetch's error before its cause (a transient one's detail keeps the tail), that the node's own
+// keep did not hold the object either.
+func (k *ObjectKeep) never() string {
+	if k == nil {
+		return ""
+	}
+	return fmt.Sprintf(" (this node's own keep of objects, %s, never held it)", k.Dir)
+}

internal/apply/references.go

@@ -27,13 +27,23 @@ type FetchObject func(ctx context.Context, name string, limit int64) ([]byte, er
 // unchanged declaration, and a node that is asleep and has no bus, apply as they always did. One object is fetched
 // once however many files name its digest.
 func ResolveFileReferences(ctx context.Context, d *declaration.Declaration, fetch FetchObject) error {
+	return ResolveFileReferencesKept(ctx, d, fetch, nil)
+}
+
+// ResolveFileReferencesKept is ResolveFileReferences with the node's own keep of objects (ObjectKeep): every content had
+// (a file here that verifies, or an object of the bus) is kept, and a kept one is used before the bus is asked. **A node
+// depends on its bucket only for content it never had** (issue 924, 2026-10-29: novox's own composition named the
+// export mesh-vault runs by a digest whose object the controller's sweep had removed, so the vault's apply failed while
+// it ran; the bucket's objects are kept only while a composition of the controller names them, and a node composing its
+// own names objects the controller no longer knows of). A nil keep keeps nothing.
+func ResolveFileReferencesKept(ctx context.Context, d *declaration.Declaration, fetch FetchObject, keep *ObjectKeep) error {
 	fetched := map[string][]byte{}
 	for i, r := range d.Resources {
 		f, ok := r.(*declaration.File)
 		if !ok || !f.IsReference() {
 			continue
 		}
-		body, err := referencedContent(ctx, f, fetch, fetched)
+		body, err := referencedContent(ctx, f, fetch, fetched, keep)
 		if err != nil {
 			return err
 		}
@@ -50,31 +60,37 @@ func ResolveFileReferences(ctx context.Context, d *declaration.Declaration, fetc
 }
 
 func referencedContent(ctx context.Context, f *declaration.File, fetch FetchObject,
-	fetched map[string][]byte) ([]byte, error) {
+	fetched map[string][]byte, keep *ObjectKeep) ([]byte, error) {
 	if body, ok := fetched[f.Digest]; ok {
 		return body, nil
 	}
-	if body, ok := alreadyThere(f); ok {
-		fetched[f.Digest] = body
-		return body, nil
-	}
 	name, err := declaration.ObjectName(f.Digest)
 	if err != nil {
 		return nil, fmt.Errorf("file %s (%s): %w", f.ID, f.Path, err)
 	}
+	if body, ok := alreadyThere(f); ok {
+		fetched[f.Digest] = body
+		keep.put(name, body)
+		return body, nil
+	}
+	if body, ok := keep.get(name, f); ok {
+		fetched[f.Digest] = body
+		return body, nil
+	}
 	if fetch == nil {
 		return nil, fmt.Errorf("file %s (%s) is given by digest %s and is not on this machine, and this node-engine "+
 			"has no link to the bus to fetch it from", f.ID, f.Path, f.Digest)
 	}
 	body, err := fetch(ctx, name, f.Size)
 	if err != nil {
-		return nil, fmt.Errorf("file %s (%s): fetching the object %s of this node's own object bucket: %w",
-			f.ID, f.Path, name, err)
+		return nil, fmt.Errorf("file %s (%s): fetching the object %s of this node's own object bucket%s: %w",
+			f.ID, f.Path, name, keep.never(), err)
 	}
 	if err := f.Verify(body); err != nil {
 		return nil, fmt.Errorf("%s (%s): %w; nothing was applied", f.ID, f.Path, err)
 	}
 	fetched[f.Digest] = body
+	keep.put(name, body)
 	return body, nil
 }
 

internal/link/access_act_test.go

@@ -6,6 +6,10 @@ import (
 	"strings"
 	"testing"
 	"time"
+
+	stdio "git.novox.be/novox/mesh-sdk/go"
+	"git.novox.be/novox/mesh-sdk/go/asker"
+	"git.novox.be/novox/mesh-sdk/go/asks"
 )
 
 // The take act's ask (novox/hq ADR 0325 §8): a hand-over's fields and the act's own in one signed object, under a
@@ -68,6 +72,112 @@ func TestTheTakeActRunsOnlyOnAWarrant(t *testing.T) {
 	if a.Said != "started" || len(given) != 1 || given[0].Warrant != "w-1" || given[0].Path != "/srv/media/movies" {
 		t.Fatalf("a warranted ask did not reach the act whole: %+v %+v", a, given)
 	}
+	// 774 (ADR 0563 §3): a hand-over asked through the node seat is the engine's own ask, performed only on the
+	// operator's warrant to it: never on the call, not on a warrant for another digest, once on a warrant heard twice,
+	// and not when the disk changed since it was asked.
+	t.Run("the node seat's hand-over acts only on the operator's warrant", func(t *testing.T) {
+		for _, row := range []struct {
+			name      string
+			warrant   func(asked asks.Ask, w asks.Warrant) asks.Warrant
+			diskAfter string
+			twice     bool
+			done      int
+			state     string
+		}{
+			{name: "no warrant", done: 0, state: HandAsked},
+			{name: "the operator's yes", warrant: yes, done: 1, state: HandDone},
+			{name: "the yes heard twice", warrant: yes, twice: true, done: 1, state: HandDone},
+			{name: "a warrant for another digest", warrant: func(a asks.Ask, w asks.Warrant) asks.Warrant {
+				w = yes(a, w)
+				w.AskDigest = "sha256:another"
+				return w
+			}, done: 0, state: HandAsked},
+			{name: "a no", warrant: func(a asks.Ask, w asks.Warrant) asks.Warrant {
+				w = yes(a, w)
+				w.Option, w.Label, w.Level = "no", "No, leave it", asks.Acknowledge
+				return w
+			}, done: 0, state: HandRefused},
+			{name: "the disk changed", warrant: yes, diskAfter: "0:0 700 9:2", done: 0, state: HandRefused},
+			{name: "expired", warrant: func(a asks.Ask, w asks.Warrant) asks.Warrant {
+				return asks.Warrant{Ask: a.ID, Asker: w.Asker, Outcome: asks.OutcomeExpired, At: w.At}
+			}, done: 0, state: HandRefused},
+		} {
+			t.Run(row.name, func(t *testing.T) {
+				h, asked, done := anEngine(t)
+				disk := "1000:1000 755 9:1"
+				h.JudgeHandOver = func(path string) (Judged, error) {
+					return Judged{Subject: path, Path: path, Sets: "owner jo, group jo, mode 0750", Disk: disk,
+						Words: "A directory used as found."}, nil
+				}
+				if _, err := h.Call(EngineCall{Verb: ActHandOver, Caller: "shanks.node-tools",
+					Args: map[string]any{"path": "/srv/x", "why": "a test"}}); err != nil {
+					t.Fatal(err)
+				}
+				if len(*asked) != 1 || *done != 0 {
+					t.Fatalf("the call asked %d and performed %d", len(*asked), *done)
+				}
+				// The act is one key, and the open ask one key made by a create (ADR 0563 §3).
+				if acts, _ := h.State.Keys("act."); len(acts) != 1 || acts[0] != "act."+(*asked)[0].ID {
+					t.Fatalf("the act is kept as %v", acts)
+				}
+				if open, _ := h.State.Keys("open."); len(open) != 1 || !strings.HasPrefix(open[0], "open.hand-over.") {
+					t.Fatalf("the open ask is kept as %v", open)
+				}
+				if _, err := h.Call(EngineCall{Verb: ActHandOver, Caller: "x", Args: map[string]any{"path": "/srv/x"}}); err == nil {
+					t.Fatal("a second ask of the same path was asked while one is open")
+				}
+				if row.diskAfter != "" {
+					disk = row.diskAfter
+				}
+				if row.warrant != nil {
+					w := row.warrant((*asked)[0], asks.Warrant{Asker: asks.EngineAsker("n1"), At: time.Now()})
+					h.Heard(w)
+					if row.twice {
+						h.Heard(w)
+					}
+				}
+				got, _ := h.Acts(0)
+				acts := got.(map[string]any)["acts"].([]HandAct)
+				if *done != row.done || len(acts) != 1 || acts[0].State != row.state {
+					t.Fatalf("performed %d (want %d), acts %+v (want %s)", *done, row.done, acts, row.state)
+				}
+				if open, _ := h.State.Keys("open."); (len(open) == 1) != (row.state == HandAsked) {
+					t.Fatalf("an ask %s leaves its open key as %v", row.state, open)
+				}
+				if row.state == HandDone && (acts[0].By != "operator" || acts[0].Via == "" || acts[0].Ask == "") {
+					t.Fatalf("the act does not record the warrant: %+v", acts[0])
+				}
+			})
+		}
+	})
+}
+
+// yes is the operator's yes to an ask, as the router writes it.
+func yes(a asks.Ask, w asks.Warrant) asks.Warrant {
+	w.Ask, w.Outcome, w.Option, w.Label, w.Level = a.ID, asks.OutcomeChosen, "yes", "Yes", asks.Approve
+	w.By = &asks.Person{Who: asks.Operator, Kind: "telegram", Verified: "user id verified"}
+	w.AskDigest, w.Proofs = a.Digest(), []string{"P1"}
+	return w
+}
+
+// anEngine is a node seat with its own state in a temporary folder, a router that keeps what it was asked, and a
+// hand-over that counts what it performed.
+func anEngine(t *testing.T) (*HandActs, *[]asks.Ask, *int) {
+	t.Helper()
+	var asked []asks.Ask
+	done := 0
+	state := &MemState{}
+	h := &HandActs{Node: "n1", State: state,
+		HandOver: func(path, by string) (string, error) { done++; return path + " handed over by " + by, nil }}
+	h.Asker = &asker.Client{Module: asks.EngineAsker("n1"), State: state,
+		Publish: func(subject string, body any, id string) error {
+			if a, ok := body.(asks.Ask); ok && subject == asks.AskSubject(asks.EngineAsker("n1")) {
+				asked = append(asked, a)
+			}
+			return nil
+		},
+		Record: func(string) (*stdio.StateEntry, error) { return nil, nil }}
+	return h, &asked, &done
 }
 
 // The controller names an access by its declared resource id exactly, which may hold a `/`: it reaches the act,

internal/link/engineseat.go

@@ -0,0 +1,382 @@
+package link
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"sort"
+	"strings"
+	"time"
+
+	stdio "git.novox.be/novox/mesh-sdk/go"
+	"git.novox.be/novox/mesh-sdk/go/asks"
+	"git.novox.be/novox/mesh-sdk/go/catalogue"
+	"github.com/nats-io/nats.go"
+	"github.com/nats-io/nats.go/micro"
+)
+
+// The node seat node-engine, served on the engine's own link (novox/hq ADR 0563 §1).
+//
+// Each verb is answered on this node's subject alone, `mesh.seat.node-engine.tool.<verb>.<node>`, and on the same
+// address naming its caller, `mesh.seat.node-engine.call.<verb>.<node>.<caller>`, whose last token the bus lets each user
+// publish with its own name alone (novox/hq issue 365): the caller is that token, and a call on the subject naming none is
+// from an unproven caller, recorded so. The body is the call's arguments; the answer is {result, error, node}, as every
+// tool's (mesh-tools node-tools). One service, `node-engine`, answers discovery with each verb's seat, tool and node.
+
+// EngineSeat is the seat.
+const EngineSeat = catalogue.EngineSeat
+
+// EngineToolSubject is where a verb of this node's seat is asked naming no caller.
+func EngineToolSubject(verb, node string) string {
+	return "mesh.seat." + EngineSeat + ".tool." + verb + "." + node
+}
+
+// EngineCallPattern is where a verb of this node's seat is asked naming its caller, any caller.
+func EngineCallPattern(verb, node string) string {
+	return "mesh.seat." + EngineSeat + ".call." + verb + "." + node + ".*"
+}
+
+// EngineEventSubject is where the seat says one of its events about this node.
+func EngineEventSubject(event, node string) string {
+	return "mesh.seat." + EngineSeat + ".event." + event + "." + node
+}
+
+// EngineCall is one call of the seat: its verb, its caller as the bus proved it, and its arguments.
+type EngineCall struct {
+	Verb   string
+	Caller string
+	Args   map[string]any
+}
+
+// EngineFunc answers one call: its result, or why it is refused.
+type EngineFunc func(EngineCall) (any, error)
+
+// CallerOfSubject is the caller a call's subject names for this node's verb: the last token of a caller-named subject,
+// each `~` a dot, or stdio.Unproven on the subject that names none or on any other.
+func CallerOfSubject(subject, verb, node string) string {
+	token, ok := strings.CutPrefix(subject, "mesh.seat."+EngineSeat+".call."+verb+"."+node+".")
+	if !ok || token == "" || strings.ContainsAny(token, ".*> ") {
+		return stdio.Unproven
+	}
+	return strings.ReplaceAll(token, "~", ".")
+}
+
+// MaxEngineCall bounds a call's arguments: a path, an access and a few words.
+const MaxEngineCall = 16 << 10
+
+// AnswerEngineCall is the envelope one call is answered with: the verb's result, or its refusal in words.
+func AnswerEngineCall(handle EngineFunc, verb, node, subject string, body []byte) []byte {
+	envelope := map[string]any{"node": node}
+	say := func() []byte {
+		raw, err := json.Marshal(envelope)
+		if err != nil {
+			raw, _ = json.Marshal(map[string]any{"node": node, "error": "the answer could not be written: " + err.Error()})
+		}
+		return raw
+	}
+	args := map[string]any{}
+	switch {
+	case handle == nil:
+		envelope["error"] = "this engine serves no verb of " + EngineSeat
+		return say()
+	case len(body) > MaxEngineCall:
+		envelope["error"] = fmt.Sprintf("the call is %d bytes, more than a call of %s takes", len(body), EngineSeat)
+		return say()
+	case len(strings.TrimSpace(string(body))) > 0:
+		if err := json.Unmarshal(body, &args); err != nil {
+			envelope["error"] = "the call's arguments are not an object: " + err.Error()
+			return say()
+		}
+	}
+	result, err := handle(EngineCall{Verb: verb, Caller: CallerOfSubject(subject, verb, node), Args: args})
+	if err != nil {
+		envelope["error"] = err.Error()
+	} else {
+		envelope["result"] = result
+	}
+	return say()
+}
+
+// EngineSeats is a link that serves this node's seat. Optional, as Asked is.
+type EngineSeats interface {
+	ServeEngineSeat(EngineFunc)
+}
+
+// ServeEngineSeat answers every verb of the seat on this node's subjects, as the service node-engine, which says each
+// verb's seat, tool and node to discovery (novox/hq ADR 0197). A bus whose user list is older than the grant refuses the
+// subscriptions, said by the client; a caller then hears nobody answer.
+func (l *natsLink) ServeEngineSeat(handle EngineFunc) {
+	if handle == nil || l.conn == nil {
+		return
+	}
+	svc, err := micro.AddService(l.conn, micro.Config{Name: EngineSeat, Version: "1.0.0",
+		Description: "the node seat node-engine of " + l.node + " (novox/hq ADR 0563)", QueueGroupDisabled: true})
+	if err != nil {
+		return
+	}
+	for _, v := range catalogue.EngineVerbs() {
+		verb := v.Name
+		answer := micro.HandlerFunc(func(r micro.Request) {
+			_ = r.Respond(AnswerEngineCall(handle, verb, l.node, r.Subject(), r.Data()))
+		})
+		meta := map[string]string{"seat": EngineSeat, "tool": verb, "node": l.node}
+		_ = svc.AddEndpoint(verb, answer, micro.WithEndpointSubject(EngineToolSubject(verb, l.node)),
+			micro.WithEndpointMetadata(meta))
+		_ = svc.AddEndpoint(verb+"-called", answer, micro.WithEndpointSubject(EngineCallPattern(verb, l.node)),
+			micro.WithEndpointMetadata(meta))
+	}
+	l.engine = svc
+}
+
+// SayEngine says one of the seat's events about this node, on the events stream.
+func (l *natsLink) SayEngine(event string, body any) error {
+	raw, err := json.Marshal(body)
+	if err != nil {
+		return err
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	_, err = l.js.Publish(EngineEventSubject(event, l.node), raw, nats.Context(ctx))
+	return err
+}
+
+// The engine asks the operator under its own asker name (asks.EngineAsker) on the router's seat (ADR 0259 §3, as ADR
+// 0563 §3 changes it): its ask and cancel on the seat's work stream, its warrants heard on its own decided subject, and
+// its asks' state read from the router's records under its own name.
+
+// RouterRecords is the router's bucket of asks, which each asker reads under its own name: the state `asks` of the
+// operator-channel's holder, the messenger (mesh-catalog modules/messenger).
+const RouterRecords = "messenger_asks"
+
+// OperatorAsks is a link that asks the operator as this node's engine. Optional.
+type OperatorAsks interface {
+	PublishAsk(subject string, body any, id string) error
+	RouterRecord(key string) (*stdio.StateEntry, error)
+	HearWarrants(asker string, heard func(asks.Warrant)) error
+}
+
+// PublishAsk publishes an ask or a cancel on the router's seat, once per id within the stream's duplicate window.
+func (l *natsLink) PublishAsk(subject string, body any, id string) error {
+	raw, err := json.Marshal(body)
+	if err != nil {
+		return err
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	_, err = l.js.Publish(subject, raw, nats.MsgId(id), nats.Context(ctx))
+	return err
+}
+
+// RouterRecord reads one key of the router's records, `<asker>.<id>`; nil when it holds none.
+func (l *natsLink) RouterRecord(key string) (*stdio.StateEntry, error) {
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	msg, err := l.conn.RequestWithContext(ctx, "$JS.API.DIRECT.GET.KV_"+RouterRecords+".$KV."+RouterRecords+"."+key, nil)
+	if err != nil {
+		return nil, err
+	}
+	if status := msg.Header.Get("Status"); status == "404" {
+		return nil, nil
+	} else if status != "" {
+		return nil, fmt.Errorf("the router's record %s could not be read: %s %s", key, status, msg.Header.Get("Description"))
+	}
+	return &stdio.StateEntry{Key: key, Value: msg.Data}, nil
+}
+
+// HearWarrants hears the warrants for asker on its decided subject, each handed to heard as it arrives.
+func (l *natsLink) HearWarrants(asker string, heard func(asks.Warrant)) error {
+	sub, err := l.conn.Subscribe(asks.DecidedSubject(asker), func(msg *nats.Msg) {
+		var w asks.Warrant
+		if json.Unmarshal(msg.Data, &w) == nil {
+			heard(w)
+		}
+	})
+	if err != nil {
+		return err
+	}
+	l.warrants = sub
+	return nil
+}
+
+// errNoAsking is a link that cannot ask the operator.
+var errNoAsking = errors.New("the link open now cannot ask the operator")
+
+// discoveryQuiet is how long the engine waits after the last answer to the bus's discovery, and discoveryMost the
+// longest it waits in all.
+const (
+	discoveryQuiet = 300 * time.Millisecond
+	discoveryMost  = 2 * time.Second
+)
+
+// HeardServed asks the bus's discovery (novox/hq ADR 0197) whether a seat's verb is answered on this machine: an
+// endpoint naming the seat, the verb as its tool and this node.
+func (l *natsLink) HeardServed(seat, verb string) (bool, error) {
+	inbox := l.conn.NewRespInbox()
+	sub, err := l.conn.SubscribeSync(inbox)
+	if err != nil {
+		return false, err
+	}
+	defer func() { _ = sub.Unsubscribe() }()
+	if err := l.conn.PublishRequest("$SRV.INFO", inbox, nil); err != nil {
+		return false, fmt.Errorf("asking the bus who serves what: %w", err)
+	}
+	heard := false
+	deadline := time.Now().Add(discoveryMost)
+	for time.Now().Before(deadline) {
+		msg, err := sub.NextMsg(discoveryQuiet)
+		if err != nil {
+			break
+		}
+		var info micro.Info
+		if json.Unmarshal(msg.Data, &info) != nil {
+			continue
+		}
+		for _, e := range info.Endpoints {
+			node := e.Metadata["node"]
+			if node == "" {
+				node = info.ID
+			}
+			if e.Metadata["seat"] == seat && e.Metadata["tool"] == verb && node == l.node {
+				heard = true
+			}
+		}
+	}
+	return heard, nil
+}
+
+// HeardServed is the link open now asking the bus's discovery whether a seat's verb is answered on this machine.
+func (q *Session) HeardServed(seat, verb string) (bool, error) {
+	q.init()
+	q.mu.Lock()
+	bus := q.bus
+	q.mu.Unlock()
+	asker, ok := bus.(interface {
+		HeardServed(string, string) (bool, error)
+	})
+	if bus == nil || !ok {
+		return false, fmt.Errorf("%w: this machine has no link to the bus open now", ErrNotAsked)
+	}
+	return asker.HeardServed(seat, verb)
+}
+
+// ---- the engine's acts in the bus's own storage (ADR 0563 §2, §3) -------------------------------------------------
+
+// actsStore is this node's keys of ActsBucket over the link open now: bound, never created (the grants part creates
+// it, as the node-engine's declared state).
+func (l *natsLink) actsStore() (nats.KeyValue, error) {
+	kv, err := l.js.KeyValue(ActsBucket)
+	if err != nil {
+		return nil, fmt.Errorf("the node-engine's state %s cannot be bound (it is created from the node-engine's "+
+			"manifest; asked again once it is): %w", ActsBucket, err)
+	}
+	return kv, nil
+}
+
+// BusState is the engine's ActStore: its own node's keys of ActsBucket, `<node>.<key>`, over whichever link the session
+// has open; with none open every read and write is refused, and nothing is kept anywhere else.
+type BusState struct {
+	Session *Session
+	Node    string
+}
+
+func (b BusState) kv() (nats.KeyValue, error) {
+	b.Session.init()
+	b.Session.mu.Lock()
+	bus := b.Session.bus
+	b.Session.mu.Unlock()
+	l, ok := bus.(interface{ actsStore() (nats.KeyValue, error) })
+	if bus == nil || !ok {
+		return nil, fmt.Errorf("%w: this machine has no link to the bus open now, where its acts are kept", ErrNotAsked)
+	}
+	return l.actsStore()
+}
+
+func (b BusState) key(k string) string { return b.Node + "." + k }
+
+// changed is a write that lost its compare-and-set, as stdio.ErrChanged.
+func changed(err error) error {
+	var api *nats.APIError
+	if errors.Is(err, nats.ErrKeyExists) || (errors.As(err, &api) && api.ErrorCode == nats.JSErrCodeStreamWrongLastSequence) {
+		return stdio.ErrChanged
+	}
+	return err
+}
+
+func (b BusState) Get(key string) (*stdio.StateEntry, error) {
+	kv, err := b.kv()
+	if err != nil {
+		return nil, err
+	}
+	e, err := kv.Get(b.key(key))
+	if errors.Is(err, nats.ErrKeyNotFound) {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+	return &stdio.StateEntry{Key: key, Value: e.Value(), Revision: e.Revision()}, nil
+}
+
+func (b BusState) Create(key string, value any) (uint64, error) {
+	kv, err := b.kv()
+	if err != nil {
+		return 0, err
+	}
+	raw, err := json.Marshal(value)
+	if err != nil {
+		return 0, err
+	}
+	rev, err := kv.Create(b.key(key), raw)
+	return rev, changed(err)
+}
+
+func (b BusState) Update(key string, value any, revision uint64) (uint64, error) {
+	kv, err := b.kv()
+	if err != nil {
+		return 0, err
+	}
+	raw, err := json.Marshal(value)
+	if err != nil {
+		return 0, err
+	}
+	rev, err := kv.Update(b.key(key), raw, revision)
+	return rev, changed(err)
+}
+
+func (b BusState) Delete(key string) error {
+	kv, err := b.kv()
+	if err != nil {
+		return err
+	}
+	return kv.Delete(b.key(key))
+}
+
+// Keys are this node's keys under prefix, without the node: a watch of `<node>.>` alone, the one filter the node's
+// grant names, its values left out.
+func (b BusState) Keys(prefix string) ([]string, error) {
+	kv, err := b.kv()
+	if err != nil {
+		return nil, err
+	}
+	w, err := kv.Watch(b.Node+".>", nats.MetaOnly(), nats.IgnoreDeletes())
+	if err != nil {
+		return nil, err
+	}
+	defer func() { _ = w.Stop() }()
+	var out []string
+	for {
+		select {
+		case e := <-w.Updates():
+			if e == nil {
+				sort.Strings(out)
+				return out, nil
+			}
+			if k := strings.TrimPrefix(e.Key(), b.Node+"."); strings.HasPrefix(k, prefix) {
+				out = append(out, k)
+			}
+		case <-time.After(10 * time.Second):
+			return nil, errors.New("the node-engine's acts could not be listed within 10s")
+		}
+	}
+}

internal/link/handacts.go

@@ -0,0 +1,769 @@
+package link
+
+import (
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"sort"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	stdio "git.novox.be/novox/mesh-sdk/go"
+	"git.novox.be/novox/mesh-sdk/go/asker"
+	"git.novox.be/novox/mesh-sdk/go/asks"
+)
+
+// The node seat node-engine's acts (novox/hq ADR 0563).
+//
+// A hand-over and an access act are the engine's own asks, performed only on the warrant (§3): a call performs nothing.
+// The engine judges every value as it does for the controller's signed ask, then refuses in words or asks the operator
+// under its own asker name (asks.EngineAsker) at the level approve, binding the digest of the verb, the node, every
+// argument and the owner, group and mode it will set. A warrant is claimed once by compare-and-set in the engine's own
+// state (asker.Client.Take), held to the ask it answers, and to the act bound and the disk as judged, judged again now;
+// only then is the act performed and recorded with the warrant. A decline, an expiry or a changed disk says refused and
+// changes nothing. One ask is open per path or access.
+//
+// The read-only verbs need no warrant (§2): judge-directories changes nothing; setuid-search is bounded here, one at a
+// time and at most one started in an hour. Every act, with who asked as the runtime proved it, is kept in the engine's own
+// declared state acts (ActsBucket, created by the grants part), under its own node's keys alone, read by the verb acts.
+
+// The acts of the seat, as its verbs name them.
+const (
+	ActHandOver         = "hand-over"
+	ActAccess           = "access-act"
+	ActJudgeDirectories = "judge-directories"
+	ActSetuidSearch     = "setuid-search"
+)
+
+// The states of an act.
+const (
+	HandAsked    = "asked"
+	HandDone     = "done"
+	HandRefused  = "refused"
+	HandAnswered = "answered"
+)
+
+// SearchEvery is how often a setuid search may be started on a node (ADR 0563 §2): one in any hour.
+const SearchEvery = time.Hour
+
+// askMargin is how long past an ask's expiry the router is given to say it ended, before the engine closes it itself.
+const askMargin = 5 * time.Minute
+
+// ActsBucket is the node-engine's declared state acts (its manifest's state, ADR 0563 §2, §3), the bucket the grants
+// part creates (mesh-sdk buscompose EngineActsBucket): keys `<node>.act.<id>`, `<node>.open.<act>.<digest>` and
+// `<node>.ask.<id>`, each written by this node's engine alone.
+const ActsBucket = "mesh-host_acts"
+
+// Judged is what the engine judged of one act before it asks: what it is about, what it will set (the owner, group and
+// mode, in words), and what the disk holds now (Disk), compared again when the warrant arrives.
+type Judged struct {
+	// Subject is the path of a hand-over, or the access of an access act.
+	Subject string
+	// Path is the directory the act changes, as the engine states it.
+	Path string
+	// Sets is the owner, group and mode the act will set, in words; bound in the ask's digest.
+	Sets string
+	// Disk is what the engine read on disk when it judged: owner, group, mode and the file it is.
+	Disk string
+	// Words is what the operator is shown of it, without a path (ADR 0234 §6): the path is in the whole words alone.
+	Words string
+}
+
+// HandAct is one act asked through the seat, as acts reads it.
+type HandAct struct {
+	ID      string    `json:"id"`
+	Act     string    `json:"act"`
+	Subject string    `json:"subject,omitempty"`
+	Caller  string    `json:"caller"`
+	Why     string    `json:"why,omitempty"`
+	At      time.Time `json:"at"`
+	State   string    `json:"state"`
+	Said    string    `json:"said,omitempty"`
+	Ended   time.Time `json:"ended,omitempty"`
+	// Ask is the operator's ask of a hand-over or an access act; Sets and Disk what was judged when it was asked.
+	Ask  string `json:"ask,omitempty"`
+	Sets string `json:"sets,omitempty"`
+	Disk string `json:"disk,omitempty"`
+	Path string `json:"path,omitempty"`
+	// Expires is when the ask ends unanswered.
+	Expires time.Time `json:"expires,omitempty"`
+	// By, Via, Proofs are the operator's warrant, recorded with the act (ADR 0563 §3).
+	By     string   `json:"by,omitempty"`
+	Via    string   `json:"via,omitempty"`
+	Proofs []string `json:"proofs,omitempty"`
+	// Auto says the engine asked it itself, on finding a library's root holding data outside its group (§4).
+	Auto bool `json:"auto,omitempty"`
+}
+
+// RootVerdict is the engine's answer to root-free (ADR 0563 §6), in the controller's words.
+type RootVerdict struct {
+	Machine string    `json:"machine"`
+	Free    bool      `json:"free"`
+	Why     string    `json:"why"`
+	Judged  time.Time `json:"judged"`
+}
+
+// HandActs is the engine's side of the seat. Every func is the engine's own judgement or act; nil refuses.
+type HandActs struct {
+	Node string
+	// State is where the acts and the asks are kept: this node's keys of ActsBucket (BusState), each key one act.
+	State ActStore
+	// Asker asks the operator as asks.EngineAsker(Node), with State as its store.
+	Asker *asker.Client
+	// JudgeHandOver judges a hand-over's path, refusing in words; HandOver records it on the warrant.
+	JudgeHandOver func(path string) (Judged, error)
+	HandOver      HandOverFunc
+	// JudgeAccess judges an access act on an access, refusing in words; AccessAct runs it on the warrant.
+	JudgeAccess func(act, access string) (Judged, error)
+	AccessAct   AccessActFunc
+	// JudgeDirectories, SetuidSearch and Searching are the read-only verbs' and whether a search runs now.
+	JudgeDirectories JudgeDirectoriesFunc
+	SetuidSearch     SetuidSearchFunc
+	Searching        func() bool
+	// RootFree is this machine's root-free verdict now.
+	RootFree func() RootVerdict
+	// Say says one of the seat's events, asked, done or refused; nil says nothing.
+	Say func(event string, body any)
+	Now func() time.Time
+	// Nonce keeps two asks of one second apart; nil is random.
+	Nonce func() string
+
+	mu sync.Mutex
+}
+
+func (h *HandActs) now() time.Time {
+	if h.Now != nil {
+		return h.Now()
+	}
+	return time.Now()
+}
+
+func (h *HandActs) nonce() string {
+	if h.Nonce != nil {
+		return h.Nonce()
+	}
+	var b [2]byte
+	_, _ = rand.Read(b[:])
+	return hex.EncodeToString(b[:])
+}
+
+func (h *HandActs) say(event string, a HandAct) {
+	if h.Say != nil {
+		h.Say(event, map[string]any{"act": a.Act, "subject": a.Subject, "caller": a.Caller, "ask": a.Ask,
+			"state": a.State, "said": a.Said, "node": h.Node})
+	}
+}
+
+// Call is the seat's one entry: a verb, the caller as the runtime proved it, and its arguments.
+func (h *HandActs) Call(c EngineCall) (any, error) {
+	arg := func(k string) string { s, _ := c.Args[k].(string); return strings.TrimSpace(s) }
+	switch c.Verb {
+	case ActHandOver:
+		return h.AskHandOver(c.Caller, arg("path"), arg("why"), false)
+	case ActAccess:
+		return h.AskAccess(c.Caller, arg("act"), arg("access"), arg("why"), false)
+	case ActJudgeDirectories:
+		return h.Judge(c.Caller)
+	case ActSetuidSearch:
+		return h.Search(c.Caller, arg("why"))
+	case "root-free":
+		if h.RootFree == nil {
+			return nil, errors.New("this engine judges no machine root-free")
+		}
+		return map[string]any{"machines": []RootVerdict{h.RootFree()}}, nil
+	case "acts":
+		if id := arg("id"); id != "" {
+			return h.Act(id)
+		}
+		limit, _ := strconv.Atoi(arg("limit"))
+		if f, ok := c.Args["limit"].(float64); ok {
+			limit = int(f)
+		}
+		return h.Acts(limit)
+	}
+	return nil, fmt.Errorf("the node seat %s serves no verb %q", EngineSeat, c.Verb)
+}
+
+// ---- the record --------------------------------------------------------------------------------------------------
+
+// ActStore is the engine's own state, this node's keys alone (BusState prefixes them with the node): each act one key,
+// written by compare-and-set on its revision, an open ask one key made by a create.
+type ActStore interface {
+	Get(key string) (*stdio.StateEntry, error)
+	Create(key string, value any) (uint64, error)
+	Update(key string, value any, revision uint64) (uint64, error)
+	Delete(key string) error
+	// Keys are the keys under prefix.
+	Keys(prefix string) ([]string, error)
+}
+
+func actKey(id string) string { return "act." + id }
+
+// openKey is the one key an open ask of act on subject holds: made by a create, so a second ask of it is refused.
+func openKey(act, subject string) string {
+	sum := sha256.Sum256([]byte(subject))
+	return "open." + act + "." + hex.EncodeToString(sum[:12])
+}
+
+// read is every act kept, oldest first.
+func (h *HandActs) read() ([]HandAct, error) {
+	keys, err := h.State.Keys("act.")
+	if err != nil {
+		return nil, fmt.Errorf("the engine's acts cannot be listed: %w", err)
+	}
+	var out []HandAct
+	for _, k := range keys {
+		a, _, err := h.readOne(k)
+		if err != nil {
+			return nil, err
+		}
+		if a != nil {
+			out = append(out, *a)
+		}
+	}
+	sort.SliceStable(out, func(i, j int) bool { return out[i].At.Before(out[j].At) })
+	return out, nil
+}
+
+func (h *HandActs) readOne(key string) (*HandAct, uint64, error) {
+	e, err := h.State.Get(key)
+	if err != nil || e == nil {
+		return nil, 0, err
+	}
+	var a HandAct
+	if err := json.Unmarshal(e.Value, &a); err != nil {
+		return nil, 0, fmt.Errorf("the engine's act %s cannot be read: %w", key, err)
+	}
+	return &a, e.Revision, nil
+}
+
+// judgedKey keeps the node's judgements and refused searches, the last keptJudged of them: any caller may ask them, so
+// they roll in one key and never add one (ADR 0563 §2: a wrong caller gains nothing, and fills no bucket).
+const (
+	judgedKey  = "judged"
+	keptJudged = 50
+)
+
+// roll adds a to the rolling key by compare-and-set, the oldest falling out.
+func (h *HandActs) roll(a HandAct) error {
+	for range 5 {
+		e, err := h.State.Get(judgedKey)
+		if err != nil {
+			return err
+		}
+		var kept []HandAct
+		if e != nil {
+			if err := json.Unmarshal(e.Value, &kept); err != nil {
+				kept = nil // an unreadable roll is started again, never a reason to refuse
+			}
+		}
+		kept = append(kept, a)
+		if len(kept) > keptJudged {
+			kept = kept[len(kept)-keptJudged:]
+		}
+		if e == nil {
+			_, err = h.State.Create(judgedKey, kept)
+		} else {
+			_, err = h.State.Update(judgedKey, kept, e.Revision)
+		}
+		if !errors.Is(err, stdio.ErrChanged) {
+			return err
+		}
+	}
+	return errors.New("the engine's judgements kept changing under its write")
+}
+
+func (h *HandActs) rolled() ([]HandAct, error) {
+	e, err := h.State.Get(judgedKey)
+	if err != nil || e == nil {
+		return nil, err
+	}
+	var kept []HandAct
+	if err := json.Unmarshal(e.Value, &kept); err != nil {
+		return nil, fmt.Errorf("the engine's judgements cannot be read: %w", err)
+	}
+	return kept, nil
+}
+
+func (h *HandActs) record(a HandAct) error {
+	_, err := h.State.Create(actKey(a.ID), a)
+	return err
+}
+
+// end marks the open act of an ask ended, once, by compare-and-set on its revision, and frees its open key: false when
+// it was not open.
+func (h *HandActs) end(ask string, set func(*HandAct)) (HandAct, bool, error) {
+	for range 5 {
+		a, rev, err := h.readOne(actKey(ask))
+		if err != nil || a == nil || a.State != HandAsked {
+			return HandAct{}, false, err
+		}
+		set(a)
+		a.Ended = h.now().UTC()
+		if _, err := h.State.Update(actKey(ask), *a, rev); errors.Is(err, stdio.ErrChanged) {
+			continue
+		} else if err != nil {
+			return HandAct{}, false, err
+		}
+		_ = h.State.Delete(openKey(a.Act, a.Subject))
+		return *a, true, nil
+	}
+	return HandAct{}, false, errors.New("the engine's act " + ask + " kept changing under its write")
+}
+
+// Act is the verb acts with an id: that one act.
+func (h *HandActs) Act(id string) (any, error) {
+	a, _, err := h.readOne(actKey(id))
+	if err != nil {
+		return nil, err
+	}
+	if a == nil {
+		return nil, fmt.Errorf("this engine keeps no act %q", id)
+	}
+	return map[string]any{"node": h.Node, "acts": []HandAct{*a}}, nil
+}
+
+// Acts is the verb acts: every act kept, newest first, at most limit when given.
+func (h *HandActs) Acts(limit int) (any, error) {
+	acts, err := h.read()
+	if err != nil {
+		return nil, err
+	}
+	judged, err := h.rolled()
+	if err != nil {
+		return nil, err
+	}
+	acts = append(acts, judged...)
+	sort.SliceStable(acts, func(i, j int) bool { return acts[i].At.Before(acts[j].At) })
+	out := make([]HandAct, 0, len(acts))
+	for i := len(acts) - 1; i >= 0; i-- {
+		out = append(out, acts[i])
+	}
+	if limit > 0 && len(out) > limit {
+		out = out[:limit]
+	}
+	return map[string]any{"node": h.Node, "acts": out}, nil
+}
+
+// ---- the read-only verbs (§2) -------------------------------------------------------------------------------------
+
+// Judge is judge-directories: the engine's judgement, read-only, recorded with its caller.
+func (h *HandActs) Judge(caller string) (any, error) {
+	if h.JudgeDirectories == nil {
+		return nil, errors.New("this engine judges no directory")
+	}
+	said, err := h.JudgeDirectories(caller)
+	a := HandAct{ID: h.id(ActJudgeDirectories), Act: ActJudgeDirectories, Caller: caller, At: h.now().UTC(), State: HandAnswered}
+	if err != nil {
+		a.State, a.Said = HandRefused, err.Error()
+	}
+	if rerr := h.roll(a); rerr != nil && err == nil {
+		return nil, rerr
+	}
+	if err != nil {
+		return nil, err
+	}
+	return map[string]any{"node": h.Node, "said": said}, nil
+}
+
+// Search is setuid-search: refused while one runs and when one was started within the hour, naming when the next may
+// start; otherwise the last search is thrown away and a full one starts, recorded with its caller.
+func (h *HandActs) Search(caller, why string) (any, error) {
+	if h.SetuidSearch == nil {
+		return nil, errors.New("this engine keeps no search for setuid programs")
+	}
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	now := h.now().UTC()
+	if h.Searching != nil && h.Searching() {
+		return nil, errors.New("a search for setuid programs runs on this machine now; no second is started while it does")
+	}
+	// The last start is a key of its own, claimed by compare-and-set before the search starts: no number of other acts,
+	// nor the record of acts, moves it (ADR 0563 §2).
+	if err := h.claimSearch(now, caller); err != nil {
+		return nil, err
+	}
+	said, err := h.SetuidSearch(caller)
+	a := HandAct{ID: h.id(ActSetuidSearch), Act: ActSetuidSearch, Caller: caller, Why: why, At: now, State: HandDone, Said: said}
+	if err != nil {
+		a.State, a.Said = HandRefused, err.Error()
+	}
+	// A search started is bounded to one an hour and kept as an act of its own; a refused one, which any caller may
+	// cause, rolls with the judgements.
+	record := h.record
+	if err != nil {
+		record = h.roll
+	}
+	if rerr := record(a); rerr != nil {
+		return nil, rerr
+	}
+	if err != nil {
+		return nil, err
+	}
+	return map[string]any{"node": h.Node, "said": said}, nil
+}
+
+// searchKey keeps the last search's start on this node, and libKey each library's own take ask: keys of their own, which
+// no other act's key moves, kept for the bucket's age (ninety days, the node-engine's manifest).
+const searchKey = "search.last"
+
+func libKey(access string) string {
+	sum := sha256.Sum256([]byte(access))
+	return "lib." + hex.EncodeToString(sum[:12]) + ".asked"
+}
+
+// started is the last search's start as kept, and who asked it.
+type started struct {
+	At time.Time `json:"at"`
+	By string    `json:"by"`
+}
+
+// claimSearch refuses a search within SearchEvery of the last start, naming when the next may start, and otherwise
+// claims this one by compare-and-set: a second claim at the same moment loses.
+func (h *HandActs) claimSearch(now time.Time, caller string) error {
+	e, err := h.State.Get(searchKey)
+	if err != nil {
+		return err
+	}
+	var rev uint64
+	if e != nil {
+		var last started
+		if err := json.Unmarshal(e.Value, &last); err != nil {
+			return fmt.Errorf("the last search's start cannot be read, so none is started: %w", err)
+		}
+		if now.Sub(last.At) < SearchEvery {
+			return fmt.Errorf("a search was started at %s by %s, and one is started in any hour: the next may start "+
+				"at %s", last.At.Format(time.RFC3339), last.By, last.At.Add(SearchEvery).Format(time.RFC3339))
+		}
+		rev = e.Revision
+	}
+	claim := started{At: now, By: caller}
+	if rev == 0 {
+		_, err = h.State.Create(searchKey, claim)
+	} else {
+		_, err = h.State.Update(searchKey, claim, rev)
+	}
+	if errors.Is(err, stdio.ErrChanged) {
+		return errors.New("another search was started at this moment; no second is started")
+	}
+	return err
+}
+
+// ---- the asks (§3, §4) --------------------------------------------------------------------------------------------
+
+func (h *HandActs) id(act string) string {
+	return act + "-" + h.now().UTC().Format("20060102t150405") + "-" + h.nonce()
+}
+
+// bound is the act an ask's yes binds: the verb, the node, every argument and what it will set (ADR 0563 §3).
+func (h *HandActs) bound(a HandAct) asks.Act {
+	act := asks.Act{"verb": a.Act, "node": h.Node, "arg.subject": a.Subject, "arg.why": a.Why, "sets": a.Sets}
+	if a.Path != "" {
+		act["path"] = a.Path
+	}
+	return act
+}
+
+// AskHandOver is hand-over: judged, refused in words or asked of the operator. auto is the engine asking by itself.
+func (h *HandActs) AskHandOver(caller, path, why string, auto bool) (any, error) {
+	if h.JudgeHandOver == nil || h.HandOver == nil {
+		return nil, errors.New("this engine takes no hand-over")
+	}
+	j, err := h.JudgeHandOver(path)
+	if err != nil {
+		return nil, err
+	}
+	return h.ask(ActHandOver, caller, why, auto, j)
+}
+
+// AskAccess is access-act: the act take on an access, judged on the library's home, refused or asked of the operator.
+func (h *HandActs) AskAccess(caller, act, access, why string, auto bool) (any, error) {
+	if h.JudgeAccess == nil || h.AccessAct == nil {
+		return nil, errors.New("this engine runs no act on an accessed folder")
+	}
+	if act != ActTake {
+		return nil, fmt.Errorf("the act asked is %q, and the one act on an access is %q", act, ActTake)
+	}
+	j, err := h.JudgeAccess(act, access)
+	if err != nil {
+		return nil, err
+	}
+	return h.ask(ActAccess, caller, why, auto, j)
+}
+
+// AskedFor says whether an act on subject was ever asked by the engine itself: a library's take is asked by itself once
+// (ADR 0563 §4), and again only by hand.
+func (h *HandActs) AskedFor(act, subject string) bool {
+	if act == ActAccess {
+		e, err := h.State.Get(libKey(subject))
+		return err != nil || e != nil // unread is never a reason to ask again
+	}
+	acts, err := h.read()
+	if err != nil {
+		return true
+	}
+	for _, a := range acts {
+		if a.Act == act && a.Subject == subject && (a.Auto || a.State == HandAsked) {
+			return true
+		}
+	}
+	return false
+}
+
+func (h *HandActs) ask(act, caller, why string, auto bool, j Judged) (any, error) {
+	if h.Asker == nil {
+		return nil, errors.New("this engine reaches no operator to ask: nothing was asked and nothing changed")
+	}
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	now := h.now().UTC()
+	a := HandAct{ID: h.id(act), Act: act, Subject: j.Subject, Path: j.Path, Caller: caller, Why: why, At: now,
+		State: HandAsked, Sets: j.Sets, Disk: j.Disk, Expires: now.Add(asks.ApproveLasts - time.Minute), Auto: auto}
+	a.Ask = a.ID
+	// One ask open per path or access: its open key made by a create, which a second ask cannot make.
+	if _, err := h.State.Create(openKey(act, j.Subject), map[string]string{"ask": a.Ask}); errors.Is(err, stdio.ErrChanged) {
+		held := "another"
+		if e, _ := h.State.Get(openKey(act, j.Subject)); e != nil {
+			var o struct {
+				Ask string `json:"ask"`
+			}
+			if json.Unmarshal(e.Value, &o) == nil && o.Ask != "" {
+				held = o.Ask
+			}
+		}
+		return nil, fmt.Errorf("%s of %s is asked already: the ask %s waits for the operator's answer", act, j.Subject, held)
+	} else if err != nil {
+		return nil, err
+	}
+	if err := h.record(a); err != nil {
+		_ = h.State.Delete(openKey(act, j.Subject))
+		return nil, err
+	}
+	bind, err := asks.ActDigest(h.bound(a))
+	if err != nil {
+		return nil, err
+	}
+	headline, does, stays := "Hand a directory on "+h.Node+" to the mesh?", "The mesh gives it "+j.Sets+".",
+		"The directory stays as it was found."
+	if act == ActAccess {
+		headline, does, stays = "Keep the library "+strings.TrimPrefix(j.Subject, "library:")+" on "+h.Node+"?",
+			"The library's group, group write and setgid are set on everything under its root.",
+			"The library waits and nothing under its root changes."
+	}
+	if len([]rune(headline)) > asks.HeadlineLength {
+		headline = string([]rune(headline)[:asks.HeadlineLength])
+	}
+	asked := asks.Ask{ID: a.Ask, Headline: headline, Who: asks.Operator,
+		Explanation: j.Words + " Your yes sets " + j.Sets + "; nothing changes until you answer.",
+		Whole:       j.Words + " (" + j.Path + ") Your yes sets " + j.Sets + "; nothing changes until you answer.",
+		Details:     "Asked by " + caller + " on " + h.Node + orWhy(why),
+		Options: []asks.Option{{ID: "yes", Label: "Yes", Does: does, Level: asks.Approve, Binds: bind},
+			{ID: "no", Label: "No, leave it", Does: stays, Level: asks.Acknowledge}},
+		Expires: a.Expires, OnExpiry: stays, About: EngineSeat + "-" + h.Node + "-" + act}
+	if err := h.Asker.Ask(asked); err != nil {
+		_, _, _ = h.end(a.Ask, func(x *HandAct) { x.State, x.Said = HandRefused, "the operator could not be asked: "+err.Error() })
+		return nil, fmt.Errorf("the operator could not be asked, and nothing changed: %w", err)
+	}
+	// Once asked, a library's own take ask is kept's own take ask: once, in a key of its own (ADR 0563 §4).
+	if auto && act == ActAccess {
+		_, _ = h.State.Create(libKey(j.Subject), map[string]any{"ask": a.Ask, "at": now})
+	}
+	h.say(HandAsked, a)
+	return map[string]any{"asked": a.Ask, "node": h.Node, "says": "the operator is asked on their channel; only " +
+		"their yes changes anything. acts shows where it stands."}, nil
+}
+
+func orWhy(why string) string {
+	if why == "" {
+		return ""
+	}
+	return ": " + why
+}
+
+// Warranted is the act on the operator's answer, handed once by asker.Client.Take after it held the warrant to the
+// ask: a no is recorded refused; a yes is held to the act the option bound and the disk as judged, judged again now,
+// and only then performed and recorded done with the warrant.
+func (h *HandActs) Warranted(o asks.Option, w asks.Warrant) error {
+	a, _, err := h.readOne(actKey(w.Ask))
+	if err != nil {
+		return err
+	}
+	if a == nil || a.State != HandAsked {
+		return fmt.Errorf("the warrant answers the ask %s, which is not open here: nothing is done", w.Ask)
+	}
+	refuse := func(why string) error {
+		ended, ok, err := h.end(w.Ask, func(x *HandAct) { x.State, x.Said = HandRefused, why; warrantOn(x, w) })
+		if err == nil && ok {
+			h.say(HandRefused, ended)
+		}
+		return err
+	}
+	if o.ID != "yes" {
+		return refuse("the operator said no")
+	}
+	var j Judged
+	switch a.Act {
+	case ActHandOver:
+		j, err = h.JudgeHandOver(a.Subject)
+	case ActAccess:
+		j, err = h.JudgeAccess(ActTake, a.Subject)
+	default:
+		err = fmt.Errorf("the act %s is not performed on a warrant", a.Act)
+	}
+	if err != nil {
+		return refuse("judged again on the operator's yes, it is refused: " + err.Error())
+	}
+	now := *a
+	now.Sets, now.Path = j.Sets, j.Path
+	if err := o.Performs(h.bound(now)); err != nil {
+		return refuse("what the yes bound is not what would be done now: " + err.Error())
+	}
+	if j.Disk != a.Disk {
+		return refuse("the disk changed since the operator was asked (" + a.Disk + ", now " + j.Disk + "): ask again")
+	}
+	// Recorded with the way it came (ADR 0563 §5): the operator's yes to this engine's ask, not a terminal's line.
+	by := operatorOf(w) + ", to " + EngineSeat + "'s ask " + w.Ask
+	var said string
+	switch a.Act {
+	case ActHandOver:
+		said, err = h.HandOver(a.Subject, by)
+	case ActAccess:
+		said, err = h.AccessAct(AccessAct{Act: ActTake, Access: a.Subject, Path: j.Path, Warrant: w.Ask, By: by})
+	}
+	if err != nil {
+		return refuse(err.Error())
+	}
+	ended, ok, err := h.end(w.Ask, func(x *HandAct) { x.State, x.Said = HandDone, said; warrantOn(x, w) })
+	if err == nil && ok {
+		h.say(HandDone, ended)
+	}
+	return err
+}
+
+func warrantOn(a *HandAct, w asks.Warrant) {
+	a.Proofs = w.Proofs
+	if w.By != nil {
+		a.By, a.Via = w.By.Who, w.By.Kind
+		if w.By.Verified != "" {
+			a.Via += " (" + w.By.Verified + ")"
+		}
+	}
+}
+
+func operatorOf(w asks.Warrant) string {
+	if w.By == nil {
+		return "the operator"
+	}
+	return "the " + w.By.Who + " via " + w.By.Kind
+}
+
+// Heard is a warrant heard on the engine's decided subject: taken once (asker.Client.Take), and an ask that ended with
+// no choice recorded refused.
+func (h *HandActs) Heard(w asks.Warrant) {
+	if h.Asker == nil {
+		return
+	}
+	// A warrant the ask kept here does not hold to (another digest, another option, too late) ends nothing: it is no
+	// answer to the ask, which stays open for the operator's.
+	if handled, _ := h.Asker.Take(w, h.Warranted); handled == asker.Recorded {
+		why := "the ask ended " + string(w.Outcome)
+		if w.Words != "" {
+			why += ": " + w.Words
+		}
+		if ended, ok, _ := h.end(w.Ask, func(x *HandAct) { x.State, x.Said = HandRefused, why; warrantOn(x, w) }); ok {
+			h.say(HandRefused, ended)
+		}
+	}
+}
+
+// Reconcile catches up what the engine missed while it was away: a warrant the router holds for an open ask is taken,
+// and an ask past its expiry and a margin is closed refused, expired.
+func (h *HandActs) Reconcile() {
+	if h.Asker == nil {
+		return
+	}
+	acts, err := h.read()
+	if err != nil {
+		return
+	}
+	for _, a := range acts {
+		if a.State != HandAsked || a.Ask == "" {
+			continue
+		}
+		if _, w, err := h.Asker.Where(a.Ask); err == nil && w != nil {
+			h.Heard(*w)
+			continue
+		}
+		if !a.Expires.IsZero() && h.now().After(a.Expires.Add(askMargin)) {
+			if ended, ok, _ := h.end(a.Ask, func(x *HandAct) { x.State, x.Said = HandRefused, "the ask expired unanswered" }); ok {
+				h.say(HandRefused, ended)
+			}
+		}
+	}
+}
+
+// MemState is an ActStore in memory: an engine's acts while no bus is reached in a test.
+type MemState struct {
+	mu   sync.Mutex
+	keys map[string]stdio.StateEntry
+	top  uint64
+}
+
+func (m *MemState) Get(key string) (*stdio.StateEntry, error) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	if e, ok := m.keys[key]; ok {
+		return &e, nil
+	}
+	return nil, nil
+}
+
+func (m *MemState) Create(key string, value any) (uint64, error) { return m.put(key, value, 0, true) }
+
+func (m *MemState) Update(key string, value any, revision uint64) (uint64, error) {
+	return m.put(key, value, revision, false)
+}
+
+func (m *MemState) put(key string, value any, revision uint64, create bool) (uint64, error) {
+	raw, err := json.Marshal(value)
+	if err != nil {
+		return 0, err
+	}
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	was, kept := m.keys[key]
+	if (create && kept) || (!create && (!kept || was.Revision != revision)) {
+		return 0, stdio.ErrChanged
+	}
+	if m.keys == nil {
+		m.keys = map[string]stdio.StateEntry{}
+	}
+	m.top++
+	m.keys[key] = stdio.StateEntry{Key: key, Value: raw, Revision: m.top}
+	return m.top, nil
+}
+
+func (m *MemState) Delete(key string) error {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	delete(m.keys, key)
+	return nil
+}
+
+func (m *MemState) Keys(prefix string) ([]string, error) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	var out []string
+	for k := range m.keys {
+		if strings.HasPrefix(k, prefix) {
+			out = append(out, k)
+		}
+	}
+	sort.Strings(out)
+	return out, nil
+}

internal/link/handover.go

@@ -76,9 +76,13 @@ const MaxHandOverBy = 200
 // HandOverCheck is what an ask is held to: the mesh's key, this node's name, the clock, and the nonces taken.
 type HandOverCheck struct {
 	Signer ed25519.PublicKey
-	Node   string
-	Now    func() time.Time
-	Nonces *Nonces
+	// SignerNow, when set, is the controller's key as the engine trusts it at this ask, read per ask in place of Signer:
+	// nil once the controller's lease is handed away, which refuses every ask signed by its key (novox/hq ADR 0563 §7,
+	// ADR 0550 §2).
+	SignerNow func() ed25519.PublicKey
+	Node      string
+	Now       func() time.Time
+	Nonces    *Nonces
 }
 
 // Nonces are the nonces of asks taken, each kept until its ask expires: an ask is taken once. Kept in memory —
@@ -157,8 +161,14 @@ func believedBytesWithin(check HandOverCheck, context string, withPath bool, bod
 	if err := json.Unmarshal(body, &signed); err != nil {
 		return HandOverAsk{}, nil, "the ask is not a signed ask: " + err.Error()
 	}
-	if len(check.Signer) != ed25519.PublicKeySize ||
-		!ed25519.Verify(check.Signer, append([]byte(context), signed.Ask...), signed.Signature) {
+	signer := check.Signer
+	if check.SignerNow != nil {
+		if signer = check.SignerNow(); signer == nil {
+			return HandOverAsk{}, nil, "the controller's lease is handed away, and no ask signed by its key is taken"
+		}
+	}
+	if len(signer) != ed25519.PublicKeySize ||
+		!ed25519.Verify(signer, append([]byte(context), signed.Ask...), signed.Signature) {
 		return HandOverAsk{}, nil, "the ask is not signed by the mesh"
 	}
 	var ask HandOverAsk

internal/link/handover_test.go

@@ -9,6 +9,9 @@ import (
 	"strings"
 	"testing"
 	"time"
+
+	stdio "git.novox.be/novox/mesh-sdk/go"
+	"github.com/nats-io/nats.go"
 )
 
 // The hand-over's ask and answer hold these field names; the controller's side holds the same list
@@ -145,6 +148,21 @@ func TestAHandOverAskIsBelievedOnlySignedForThisNodeUnexpiredAndOnce(t *testing.
 	if strings.Join(given, "; ") != "/srv/notes by jo through mesh-cli on anchor; /refused by jo through mesh-cli on anchor" {
 		t.Fatalf("the handler was given %v", given)
 	}
+	// ADR 0563 §7, ADR 0550 §2: after the lease write the engine answers no ask signed by the controller's key. The key
+	// is read per ask from what the engine trusts now; nil (the lease handed away) refuses, and nothing is handed over.
+	trusted := m.Signer
+	following := HandOverCheck{Signer: m.Signer, SignerNow: func() ed25519.PublicKey { return trusted }, Node: m.Node,
+		Now: func() time.Time { return now }, Nonces: &Nonces{}}
+	before := len(given)
+	trusted = nil
+	late := signedAsk(t, key, with(func(a *HandOverAsk) { a.Expires = now.Add(time.Minute); a.Nonce = strings.Repeat("cd", 16) }))
+	if a := AnswerHandOver(following, handle, late); !strings.Contains(a.Refused, "lease is handed away") || len(given) != before {
+		t.Fatalf("after the lease write an ask signed by the controller was answered %+v", a)
+	}
+	trusted = m.Signer
+	if a := AnswerHandOver(following, handle, late); a.Refused != "" || len(given) != before+1 {
+		t.Fatalf("while the controller holds the lease its ask was answered %+v", a)
+	}
 	// A nonce is forgotten once its ask has expired, so the set does not grow for ever.
 	now = now.Add(HandOverGood + time.Second)
 	check.Nonces.take("ff", now.Add(time.Second), now)
@@ -174,17 +192,23 @@ func TestAHandOverIsAnsweredOnlyWhenItCarriesAReply(t *testing.T) {
 // handingLink is a quiet link that hears hand-overs, keeping the handler it was given.
 type handingLink struct {
 	*quietLink
-	given chan HandOverFunc
+	given  chan HandOverFunc
+	signer chan func() ed25519.PublicKey
 }
 
 func (l handingLink) HearHandOvers(h HandOverFunc) { l.given <- h }
 
+// FollowSigner keeps what the link is told to verify the controller's asks with.
+func (l handingLink) FollowSigner(f func() ed25519.PublicKey) { l.signer <- f }
+
 // **The link is given the queue's hand-over** when it is served: what the controller asks reaches the engine's
 // judgement, and nothing else.
 func TestALinkThatHearsHandOversIsGivenTheQueues(t *testing.T) {
 	m, _ := aMember(t)
-	l := handingLink{quietLink: newQuietLink(), given: make(chan HandOverFunc, 1)}
+	l := handingLink{quietLink: newQuietLink(), given: make(chan HandOverFunc, 1), signer: make(chan func() ed25519.PublicKey, 1)}
 	q := &Session{Membership: m, Timeout: time.Second}
+	// The link verifies the controller's asks with the key the engine trusts now (ADR 0563 §7).
+	q.ControllerKey = func() ed25519.PublicKey { return nil }
 	q.HandOver = func(path, by string) (string, error) { return "the queue's: " + path + " by " + by, nil }
 	ctx, stop := context.WithCancel(context.Background())
 	served := make(chan error, 1)
@@ -197,8 +221,40 @@ func TestALinkThatHearsHandOversIsGivenTheQueues(t *testing.T) {
 	case <-time.After(5 * time.Second):
 		t.Fatal("the link was never given the queue's hand-over")
 	}
+	select {
+	case f := <-l.signer:
+		if f() != nil {
+			t.Fatal("the link was given another key than the queue's")
+		}
+	case <-time.After(5 * time.Second):
+		t.Fatal("the link was never given the key the engine trusts now")
+	}
 	stop()
 	<-served
+	// 774 (ADR 0563 §1): a call of the node seat reaches its verb with its caller as the subject proves it, unproven on
+	// the subject that names none; a verb the seat does not serve is refused, and the answer is a tool's envelope.
+	t.Run("a call of the node seat reaches its verb with its proven caller", func(t *testing.T) {
+		h := &HandActs{Node: "n1", State: &MemState{},
+			RootFree:         func() RootVerdict { return RootVerdict{Machine: "n1", Free: true, Why: "judged"} },
+			JudgeDirectories: func(by string) (string, error) { return "judged for " + by, nil }}
+		for _, row := range []struct{ verb, subject, want string }{
+			{"judge-directories", "mesh.seat.node-engine.call.judge-directories.n1.shanks~node-tools", `"said":"judged for shanks.node-tools"`},
+			{"judge-directories", EngineToolSubject("judge-directories", "n1"), `"said":"judged for unproven"`},
+			{"judge-directories", "mesh.seat.node-engine.call.judge-directories.n2.shanks~node-tools", `"said":"judged for unproven"`},
+			{"root-free", "mesh.seat.node-engine.call.root-free.n1.ace~messenger", `"free":true`},
+			{"unserved", "mesh.seat.node-engine.call.unserved.n1.x", `"error":"the node seat node-engine serves no verb \"unserved\""`},
+		} {
+			if got := string(AnswerEngineCall(h.Call, row.verb, "n1", row.subject, []byte(`{}`))); !strings.Contains(got, row.want) ||
+				!strings.Contains(got, `"node":"n1"`) {
+				t.Errorf("%s on %s: %s", row.verb, row.subject, got)
+			}
+		}
+		acts, _ := h.Acts(0)
+		if got := acts.(map[string]any)["acts"].([]HandAct); len(got) != 3 || got[0].Caller != "unproven" ||
+			got[2].Caller != "shanks.node-tools" || got[2].Act != ActJudgeDirectories {
+			t.Errorf("the judgements are recorded as %+v", got)
+		}
+	})
 }
 
 // **Against a real server**: a signed request on the node's own subject is answered; one on another node's is
@@ -237,4 +293,63 @@ func TestNatsAHandOverIsAskedOfTheNode(t *testing.T) {
 	if len(handled) != 1 {
 		t.Fatalf("handled %d asks; want only the one with a reply", len(handled))
 	}
+	// 774 (ADR 0563 §2, §3): the engine's acts are its node's keys of its declared state on the bus, each written by
+	// compare-and-set: a second create and a stale revision lose, and another node's keys are not this node's.
+	t.Run("the acts are kept in the bus's own storage under this node's keys", func(t *testing.T) {
+		_ = js.DeleteKeyValue(ActsBucket)
+		if _, err := js.CreateKeyValue(&nats.KeyValueConfig{Bucket: ActsBucket}); err != nil {
+			t.Fatal(err)
+		}
+		q := &Session{Membership: m, Timeout: time.Second}
+		q.bus = l
+		mine, theirs := BusState{Session: q, Node: m.Node}, BusState{Session: q, Node: "another"}
+		rev, err := mine.Create("act.a-1", map[string]string{"state": "asked"})
+		if err != nil {
+			t.Fatal(err)
+		}
+		if _, err := mine.Create("act.a-1", map[string]string{}); !errors.Is(err, stdio.ErrChanged) {
+			t.Errorf("a second create: %v", err)
+		}
+		if _, err := mine.Update("act.a-1", map[string]string{"state": "done"}, rev+7); !errors.Is(err, stdio.ErrChanged) {
+			t.Errorf("an update at a stale revision: %v", err)
+		}
+		if _, err := mine.Update("act.a-1", map[string]string{"state": "done"}, rev); err != nil {
+			t.Errorf("an update at its revision: %v", err)
+		}
+		_, _ = theirs.Create("act.b-1", map[string]string{})
+		if keys, err := mine.Keys("act."); err != nil || len(keys) != 1 || keys[0] != "act.a-1" {
+			t.Errorf("this node's acts are %v, %v", keys, err)
+		}
+		if e, _ := js.KeyValue(ActsBucket); e != nil {
+			if got, err := e.Get(m.Node + ".act.a-1"); err != nil || !strings.Contains(string(got.Value()), "done") {
+				t.Errorf("the bucket holds %v, %v", got, err)
+			}
+		}
+		if err := mine.Delete("act.a-1"); err != nil {
+			t.Fatal(err)
+		}
+		if e, err := mine.Get("act.a-1"); err != nil || e != nil {
+			t.Errorf("a deleted act reads %v, %v", e, err)
+		}
+	})
+	// 774 (ADR 0563 §1): the node seat is served on this node's subjects alone, naming its caller, and said to discovery.
+	t.Run("the node seat is served on this node and discovered", func(t *testing.T) {
+		l.ServeEngineSeat(func(c EngineCall) (any, error) { return c.Verb + " for " + c.Caller, nil })
+		reply, err := conn.Request("mesh.seat.node-engine.call.acts."+m.Node+".shanks~node-tools", []byte(`{}`), 5*time.Second)
+		if err != nil || !strings.Contains(string(reply.Data), `"result":"acts for shanks.node-tools"`) {
+			t.Fatalf("the call answered %v, %v", reply, err)
+		}
+		if _, err := conn.Request(EngineToolSubject("acts", "another"), []byte(`{}`), 300*time.Millisecond); err == nil {
+			t.Fatal("another node's verb was answered here")
+		}
+		for seat, want := range map[string]bool{EngineSeat: true, "node-login-shell": false} {
+			verb := "acts"
+			if !want {
+				verb = "execute"
+			}
+			if heard, err := l.HeardServed(seat, verb); err != nil || heard != want {
+				t.Errorf("discovery hears %s.%s here: %v, %v", seat, verb, heard, err)
+			}
+		}
+	})
 }

internal/link/have_test.go

@@ -274,7 +274,8 @@ func TestTheReportIsSentFirstAndTheNodeKeyCarriesTheNodesFacts(t *testing.T) {
 	// 1126 (ADR 0555 §3): with its keys, the node key carries the node's record: the profile's present capabilities and
 	// networks, the outward links, the health's contract and the public keys; a report that changes none of it writes
 	// nothing, a changed fact writes the key once, and a report without a profile or health leaves them standing.
-	keys := RecordKeys{TunnelKey: "tk", SealingKey: "sk", ServingKey: "pk", Certificate: "cert"}
+	keys := RecordKeys{TunnelKey: "tk", SealingKey: "sk", ServingKey: "pk", Certificate: "cert",
+		Trusts: []string{"controller key sha256:aa", "vault key sha256:bb"}} // and what it trusts (L3 s6, ADR 0550 §2)
 	q.Keys = func() RecordKeys { return keys }
 	rep.Profile = map[string]any{"capabilities": []any{map[string]any{"name": "systemd", "present": true},
 		map[string]any{"name": "docker", "present": false}, map[string]any{"name": "apt", "present": true}},
@@ -286,7 +287,7 @@ func TestTheReportIsSentFirstAndTheNodeKeyCarriesTheNodesFacts(t *testing.T) {
 		t.Fatalf("the node key holds no record: %+v, %v", got, err)
 	}
 	wantRecord := delivery.NodeRecord{V: delivery.Version, Node: "n1", TunnelKey: "tk", SealingKey: "sk", ServingKey: "pk",
-		Certificate: "cert", Capabilities: []string{"apt", "systemd"}, OutwardLinks: []string{"eth0"}, NetworksSaid: true,
+		Certificate: "cert", Trusts: keys.Trusts, Capabilities: []string{"apt", "systemd"}, OutwardLinks: []string{"eth0"}, NetworksSaid: true,
 		Networks: []catalogue.AttachedNetwork{{Link: "eth0", Network: "192.0.2.0/24"}}, Contract: NodeKeyContract}
 	if !delivery.SameNodeRecord(*got.Record, wantRecord) {
 		t.Errorf("record = %+v, want %+v", *got.Record, wantRecord)

internal/link/health_test.go

@@ -3,9 +3,12 @@ package link
 import (
 	"context"
 	"encoding/json"
+	"slices"
 	"strings"
 	"testing"
 	"time"
+
+	"git.novox.be/novox/mesh-sdk/go/delivery"
 )
 
 // A health statement is said on the link open now, as the machine's own word on its own subject, and
@@ -50,6 +53,101 @@ func TestAHealthStatementIsSaidOnTheLinkOpenNow(t *testing.T) {
 	if HealthSubject("anchor") != "mesh.control.anchor.health" {
 		t.Fatalf("the subject %s is not inside the host's own grant", HealthSubject("anchor"))
 	}
+
+	// Issue 774: the node's own health report in its key of mesh-host_health, for the watchman's six alerts: written on
+	// a change only, the streaks and the time of the look not being one, and read first after a restart.
+	t.Run("the node's health report is written on a change only", func(t *testing.T) {
+		since := time.Date(2026, 10, 29, 20, 0, 0, 0, time.UTC)
+		look := func(streak int, writer string) Health {
+			return Health{Contract: 7, At: time.Now(), Network: &NetworkHealth{State: StateUnhealthy, Since: since, Parts: []NetworkPart{
+				{Part: "resolv-conf", State: StateUnhealthy, Writer: writer, Owner: "dnsmasq", Since: since, Streak: streak}}},
+				Units: &UnitsHealth{State: "degraded", Failed: []FailedUnit{{Unit: "cups.service", Scope: "system", Since: since}}},
+				Resources: []ResourceHealth{
+					{Module: "brother", Resource: "brother.scanner", Kind: KindAccount, Account: "jochen", State: StateUnhealthy,
+						Reason: "relogin needed: the session began before scanner", Since: since},
+					{Module: "photos", Resource: "photos.library", Kind: KindDirectory, Target: "/srv/photos", State: StateUnhealthy,
+						Reason: ReasonUsedAsFound + " owned by root", Since: since},
+					{Module: "letta", Resource: "letta.server", Kind: "container", State: StateHealthy, Since: since},
+					{Module: "claude-code", Resource: "claude-code.agent", Kind: KindAccount, Account: "agent", Root: "never",
+						State: StateHealthy, Since: since}}}
+		}
+		peers := []PeerSeen{{Key: "B=", Seen: true}, {Key: "A=", Addresses: []string{"10.10.0.2/32"}}}
+		r := NodeHealthOf("anchor", look(1, "NetworkManager"), peers, Machines{})
+		if r.Network.Parts[0].Writer != "NetworkManager" || r.Network.Parts[0].Streak != 0 || r.Peers[0].Key != "A=" ||
+			len(r.Units.Failed) != 1 || len(r.Relogin) != 1 || r.Relogin[0].Account != "jochen" ||
+			len(r.Found) != 1 || r.Found[0].Path != "/srv/photos" ||
+			len(r.Root) != 1 || r.Root[0].Account != "agent" || r.Root[0].State != StateHealthy || r.Contract != 7 {
+			t.Fatalf("the report is %+v", r)
+		}
+		// The machines an unhealthy part points at, as the controller holds it there; none for the machine's own.
+		machines := Machines{ByAddress: map[string]string{"10.10.0.1": "novox", "10.10.0.4": "ace", "10.10.0.9": "anchor"}, Hub: "novox"}
+		for _, tc := range []struct {
+			name   string
+			toward []string
+			state  string
+			want   []string
+		}{
+			{"the tunnel to the hub", []string{"hub"}, StateUnhealthy, []string{"novox"}},
+			{"two mesh resolvers", []string{"10.10.0.1", "10.10.0.4"}, StateUnhealthy, []string{"novox", "ace"}},
+			{"a resolver a VPN client wrote in is the machine's own", []string{"10.10.0.1", "192.0.2.53"}, StateUnhealthy, nil},
+			{"its own resolver is its own", []string{"10.10.0.9"}, StateUnhealthy, nil},
+			{"a healthy part points at nothing", []string{"hub"}, StateHealthy, nil},
+		} {
+			h := Health{Network: &NetworkHealth{State: tc.state, Parts: []NetworkPart{{Part: "names", State: tc.state, Toward: tc.toward}}}}
+			got := NodeHealthOf("anchor", h, nil, machines).Network.Parts[0].Targets
+			if !slices.Equal(got, tc.want) {
+				t.Errorf("%s: targets %v, want %v", tc.name, got, tc.want)
+			}
+		}
+		store := &memHealth{}
+		var last *NodeHealth
+		clock := func() time.Time { return since }
+		for i, step := range []struct {
+			h     NodeHealth
+			fresh bool // a restart: nothing written in this run yet
+			wrote bool
+		}{
+			{h: r, wrote: true},
+			{h: NodeHealthOf("anchor", look(2, "NetworkManager"), peers, Machines{})},
+			{h: NodeHealthOf("anchor", look(3, "NetworkManager"), peers, Machines{}), fresh: true},
+			{h: NodeHealthOf("anchor", look(3, "openvpn"), peers, Machines{}), wrote: true},
+			{h: NodeHealthOf("anchor", look(3, "openvpn"), []PeerSeen{{Key: "A=", Seen: true}}, Machines{}), wrote: true},
+		} {
+			if step.fresh {
+				last = nil
+			}
+			wrote, err := writeNodeHealth(t.Context(), store, &last, step.h, clock)
+			if err != nil || wrote != step.wrote {
+				t.Fatalf("step %d: wrote %v (want %v), %v", i, wrote, step.wrote, err)
+			}
+		}
+		got, err := delivery.DecodeNodeHealth(store.values["anchor"])
+		if err != nil || got.Node != "anchor" || got.Network.Parts[0].Writer != "openvpn" || !got.Peers[0].Seen || got.At.IsZero() {
+			t.Fatalf("the key holds %+v, %v", got, err)
+		}
+		// The key's bytes are mesh-sdk's layout: decoded and encoded again by it, the same bytes.
+		if again, err := delivery.EncodeNodeHealth(got); err != nil || string(again) != string(store.values["anchor"]) {
+			t.Fatalf("the key's bytes are not the sdk's layout: %s\n%s (%v)", store.values["anchor"], again, err)
+		}
+		if store.puts != 3 {
+			t.Fatalf("%d writes, want 3: one per change", store.puts)
+		}
+	})
+}
+
+// memHealth is a HealthStore in memory.
+type memHealth struct {
+	values map[string][]byte
+	puts   int
+}
+
+func (m *memHealth) Get(_ context.Context, key string) ([]byte, error) { return m.values[key], nil }
+func (m *memHealth) Put(_ context.Context, key string, value []byte) error {
+	if m.values == nil {
+		m.values = map[string][]byte{}
+	}
+	m.values[key], m.puts = value, m.puts+1
+	return nil
 }
 
 // A declared tool check reads the node tools' reply envelope: healthy only when the tool says so (novox/hq

internal/link/hearing_nats.go

@@ -6,9 +6,11 @@ import (
 	"errors"
 	"fmt"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/nats-io/nats.go"
+	"github.com/nats-io/nats.go/micro"
 )
 
 // The host's link on the bus: one connection, and what is asked of this node over it. The node hears no declaration
@@ -35,11 +37,14 @@ func natsURL(address string) string {
 
 // natsLink is this node's connection as a JetStream subscription.
 type natsLink struct {
-	conn    *nats.Conn
-	js      nats.JetStreamContext
-	asking  *nats.Subscription
-	asked   chan struct{}
-	handing *nats.Subscription
+	// mu guards signerNow (FollowSigner).
+	mu        sync.Mutex
+	signerNow func() ed25519.PublicKey
+	conn      *nats.Conn
+	js        nats.JetStreamContext
+	asking    *nats.Subscription
+	asked     chan struct{}
+	handing   *nats.Subscription
 	// searching hears the controller's terminal asking for a fresh setuid search (novox/hq issue 361).
 	searching *nats.Subscription
 	// judging hears the controller asking for a read-only judgement of this node's directories (issue 358).
@@ -48,7 +53,10 @@ type natsLink struct {
 	acting *nats.Subscription
 	// moving hears the controller asking to move a value sealed to this machine into the vault (issue 676).
 	moving *nats.Subscription
-	node   string
+	// engine serves the node seat node-engine, and warrants hears the operator's answers to its asks (ADR 0563).
+	engine   micro.Service
+	warrants *nats.Subscription
+	node     string
 	// signer is the mesh's key, which a hand-over ask is verified with as a declaration is (issue 356).
 	signer ed25519.PublicKey
 	lost   chan error
@@ -141,6 +149,21 @@ func (l *natsLink) hearAsks() {
 	}
 }
 
+// FollowSigner has every signed ask heard on this link verified with the key the engine trusts at that ask, the
+// controller's while it holds its lease and none from its hand-over (novox/hq ADR 0563 §7, ADR 0550 §2).
+func (l *natsLink) FollowSigner(f func() ed25519.PublicKey) {
+	l.mu.Lock()
+	l.signerNow = f
+	l.mu.Unlock()
+}
+
+// check is how a signed ask is believed on this link: the static membership signer until FollowSigner names the trust.
+func (l *natsLink) check() HandOverCheck {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	return HandOverCheck{Signer: l.signer, SignerNow: l.signerNow, Node: l.node}
+}
+
 // HearHandOvers listens for the controller asking this node to hand a directory used as found to the mesh
 // (novox/hq issue 356): a request on this machine's own subject, answered once on the reply it carried. The
 // ask is verified with the mesh's key before anything is read out of it (AnswerHandOver), because a responder
@@ -151,7 +174,7 @@ func (l *natsLink) HearHandOvers(handle HandOverFunc) {
 	if handle == nil {
 		return
 	}
-	check := HandOverCheck{Signer: l.signer, Node: l.node}
+	check := l.check()
 	handing, err := l.conn.Subscribe(AskHandOverSubject(l.node), func(msg *nats.Msg) {
 		if body, answer := HandOverReply(check, handle, msg.Reply, msg.Data); answer {
 			_ = msg.Respond(body)
@@ -170,7 +193,7 @@ func (l *natsLink) HearSetuidSearches(handle SetuidSearchFunc) {
 	if handle == nil {
 		return
 	}
-	check := HandOverCheck{Signer: l.signer, Node: l.node}
+	check := l.check()
 	searching, err := l.conn.Subscribe(AskSetuidSearchSubject(l.node), func(msg *nats.Msg) {
 		if body, answer := SetuidSearchReply(check, handle, msg.Reply, msg.Data); answer {
 			_ = msg.Respond(body)
@@ -189,7 +212,7 @@ func (l *natsLink) HearDirectoryJudgements(handle JudgeDirectoriesFunc) {
 	if handle == nil {
 		return
 	}
-	check := HandOverCheck{Signer: l.signer, Node: l.node}
+	check := l.check()
 	judging, err := l.conn.Subscribe(AskJudgeDirectoriesSubject(l.node), func(msg *nats.Msg) {
 		if body, answer := JudgeDirectoriesReply(check, handle, msg.Reply, msg.Data); answer {
 			_ = msg.Respond(body)
@@ -207,7 +230,7 @@ func (l *natsLink) HearAccessActs(handle AccessActFunc) {
 	if handle == nil {
 		return
 	}
-	check := HandOverCheck{Signer: l.signer, Node: l.node}
+	check := l.check()
 	acting, err := l.conn.Subscribe(AskAccessActSubject(l.node), func(msg *nats.Msg) {
 		if body, answer := AccessActReply(check, handle, msg.Reply, msg.Data); answer {
 			_ = msg.Respond(body)
@@ -225,7 +248,7 @@ func (l *natsLink) HearMoveSecrets(handle MoveSecretFunc) {
 	if handle == nil {
 		return
 	}
-	check := HandOverCheck{Signer: l.signer, Node: l.node}
+	check := l.check()
 	moving, err := l.conn.Subscribe(AskMoveSecretSubject(l.node), func(msg *nats.Msg) {
 		if body, answer := MoveSecretReply(check, handle, msg.Reply, msg.Data); answer {
 			_ = msg.Respond(body)
@@ -258,6 +281,12 @@ func (l *natsLink) Close() {
 	if l.judging != nil {
 		_ = l.judging.Unsubscribe()
 	}
+	if l.engine != nil {
+		_ = l.engine.Stop()
+	}
+	if l.warrants != nil {
+		_ = l.warrants.Unsubscribe()
+	}
 	if l.conn != nil {
 		l.conn.Close()
 	}
@@ -301,10 +330,12 @@ func (l *natsLink) Ask(ctx context.Context, subject string, body []byte) ([]byte
 // What the queue asks of a live link beside Bus, each by a type assertion that fails quietly: said here
 // so a link that drops one does not build.
 var (
-	_ Bus       = (*natsLink)(nil)
-	_ HealthBus = (*natsLink)(nil)
-	_ HaveBus   = (*natsLink)(nil)
-	_ ToolBus   = (*natsLink)(nil)
-	_ Asker     = (*natsLink)(nil)
-	_ Asked     = (*natsLink)(nil)
+	_ Bus          = (*natsLink)(nil)
+	_ HealthBus    = (*natsLink)(nil)
+	_ HaveBus      = (*natsLink)(nil)
+	_ ToolBus      = (*natsLink)(nil)
+	_ Asker        = (*natsLink)(nil)
+	_ Asked        = (*natsLink)(nil)
+	_ EngineSeats  = (*natsLink)(nil)
+	_ OperatorAsks = (*natsLink)(nil)
 )

internal/link/messages.go

@@ -313,58 +313,14 @@ const KindRunner = "runner"
 // ReasonUsedAsFound starts the reason of a directory used as found.
 const ReasonUsedAsFound = "used as found:"
 
-// UnitsHealth is the machine's service managers in one statement (issue 315).
-type UnitsHealth struct {
-	// State is running, degraded — a unit failed, the modules' or the machine's — or unknown when no
-	// manager could be read.
-	State string `json:"state"`
-	// Failed is every unit failed on two looks in a row that no module places: the machine's own.
-	Failed []FailedUnit `json:"failed"`
-	// Unread names a manager that could not be read, with why.
-	Unread []string `json:"unread,omitempty"`
-	// Away names an account's own manager not running, so not read: nothing in it is failed (issue 764).
-	Away []string `json:"away,omitempty"`
-}
-
-// FailedUnit is one failed unit no module places.
-type FailedUnit struct {
-	Unit string `json:"unit"`
-	// Scope is system, or user: an account's own manager.
-	Scope string `json:"scope"`
-	// Load is loaded, not-found — a unit whose file is gone and whose failure its manager still holds…
-	Load string `json:"load,omitempty"`
-	// Result is how it failed: exit-code, timeout, start-limit-hit…
-	Result string `json:"result,omitempty"`
-	// Resource is the mesh's own resource that names it, when the mesh placed it in its own right.
-	Resource string    `json:"resource,omitempty"`
-	Since    time.Time `json:"since"`
-}
-
-// NetworkHealth is the machine's networking in one statement (ADR 0241): the worst of its parts, since
-// when, and each part.
-type NetworkHealth struct {
-	State string        `json:"state"`
-	Since time.Time     `json:"since"`
-	Parts []NetworkPart `json:"parts"`
-}
-
-// NetworkPart is one part of a machine's networking, as its engine judged it on its second look.
-type NetworkPart struct {
-	// Part is resolv-conf, names, tunnel, bus or route.
-	Part  string `json:"part"`
-	State string `json:"state"`
-	// Reason is why it is not healthy, in words with no address, path or domain; Said the detail.
-	Reason string `json:"reason,omitempty"`
-	Said   string `json:"said,omitempty"`
-	// Writer is the program that rewrote the resolver file, when it can be named; Owner the module whose
-	// file it is — the uplink's holder.
-	Writer string `json:"writer,omitempty"`
-	Owner  string `json:"owner,omitempty"`
-	// Toward is what the failure points at: "hub", or each resolver's address that failed.
-	Toward []string  `json:"toward,omitempty"`
-	Since  time.Time `json:"since"`
-	Streak int       `json:"streak,omitempty"`
-}
+// The machine's networking and its service managers in a statement are the node's health report's parts (mesh-sdk
+// delivery, issue 774): one layout for the message, the report and the watchman that reads it.
+type (
+	NetworkHealth = delivery.NetworkHealth
+	NetworkPart   = delivery.NetworkPart
+	UnitsHealth   = delivery.UnitsHealth
+	FailedUnit    = delivery.FailedUnit
+)
 
 // The states a long-running resource is said in (ADR 0240 §4).
 const (

internal/link/nodehealth.go

@@ -0,0 +1,208 @@
+package link
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"slices"
+	"sort"
+	"strings"
+	"time"
+
+	"git.novox.be/novox/mesh-sdk/go/declaration"
+	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"github.com/nats-io/nats.go"
+)
+
+// The node-engine's own health report in the bus's own storage (issue 774, the operator's alert table, 2026-10-29): one
+// key per node, `<node>`, of the engine's declared state `health` (HealthBucket, created by the grants part from the
+// engine's manifest as its state `acts` is), written by this node's engine alone and only when what it says changed.
+// The watchman (seat mesh-watchdogs) reads it for six alerts the controller raised from the passing health message:
+//
+//   - machine-network: Network, the machine's route, tunnel, name servers, resolver file and bus, each a part;
+//   - network-rewritten: the resolver file's part, unhealthy with Writer, the program that rewrote it, and Owner, the
+//     module whose file it is;
+//   - network-unreachable: Peers, each peer of the mesh's tunnel and whether this machine saw it within five minutes,
+//     read across every node's report;
+//   - machine-units: Units, the failed system units no module owns;
+//   - relogin-needed: Relogin, each account whose running session lacks a group it was given;
+//   - directory-used-as-found: Found, each directory a module declares that the engine uses as found.
+//
+
+// The report's layout is mesh-sdk's (delivery.NodeHealth): the bucket, its version and its parts.
+const (
+	HealthBucket      = delivery.NodeHealthBucket
+	NodeHealthVersion = delivery.NodeHealthVersion
+)
+
+type (
+	NodeHealth    = delivery.NodeHealth
+	PeerSeen      = delivery.PeerSeen
+	NodeAccount   = delivery.NodeAccount
+	NodeDirectory = delivery.NodeDirectory
+)
+
+// ReasonReloginNeeded starts an account's reason when its session needs a new login (accounts.ReasonRelogin).
+const ReasonReloginNeeded = "relogin needed"
+
+// Machines names the mesh's machines for a report's targets: each node by its address on the private network, and the
+// hub's node. The zero value names none, and every part is then the machine's own.
+type Machines struct {
+	ByAddress map[string]string
+	Hub       string
+}
+
+// targets is the machines a part points at, as the controller holds it (mesh-controller machine_network.go): the hub's
+// node for TowardHub, each resolver's node by its address; none when it points at nothing, or at this machine or an
+// address no other mesh machine has, as one of them makes the part the machine's own.
+func (m Machines) targets(node string, toward []string) []string {
+	if len(toward) == 0 {
+		return nil
+	}
+	var out []string
+	for _, t := range toward {
+		x := m.ByAddress[t]
+		if t == TowardHub {
+			x = m.Hub
+		}
+		if x == "" || x == node {
+			return nil
+		}
+		if !slices.Contains(out, x) {
+			out = append(out, x)
+		}
+	}
+	return out
+}
+
+// TowardHub is what a part failing toward the hub names in Toward (network.TowardHub).
+const TowardHub = "hub"
+
+// NodeHealthOf is the report a health statement and the tunnel's peers make: the statement's network without its
+// streaks, each unhealthy part naming the machines it points at (machines), its machine units, and each account and
+// directory of its resources that the six alerts read.
+func NodeHealthOf(node string, h Health, peers []PeerSeen, machines Machines) NodeHealth {
+	out := NodeHealth{V: NodeHealthVersion, Node: node, Units: h.Units, Contract: h.Contract}
+	if len(peers) > 0 {
+		out.Peers = append([]PeerSeen(nil), peers...)
+		sort.Slice(out.Peers, func(i, k int) bool { return out.Peers[i].Key < out.Peers[k].Key })
+	}
+	if h.Network != nil {
+		n := NetworkHealth{State: h.Network.State, Since: h.Network.Since, Parts: make([]NetworkPart, 0, len(h.Network.Parts))}
+		for _, p := range h.Network.Parts {
+			p.Streak = 0 // a look's count moves every look; the report says a part's state, not how often it was seen
+			p.Targets = nil
+			if p.State == StateUnhealthy {
+				p.Targets = machines.targets(node, p.Toward)
+			}
+			n.Parts = append(n.Parts, p)
+		}
+		out.Network = &n
+	}
+	for _, r := range h.Resources {
+		// Each alert reads its own: an account may need a new login and be declared never to become root at once.
+		if r.Kind == KindAccount && r.State == StateUnhealthy && strings.HasPrefix(r.Reason, ReasonReloginNeeded) {
+			out.Relogin = append(out.Relogin, NodeAccount{Account: r.Account, Module: r.Module, Resource: r.Resource,
+				Reason: r.Reason, Since: r.Since})
+		}
+		if r.Kind == KindAccount && r.Root == declaration.RootNever {
+			// The account declared never to become root without a person, judged (ADR 0266): what DA and D-root read.
+			out.Root = append(out.Root, delivery.RootVerdict{Account: r.Account, Module: r.Module, Resource: r.Resource,
+				State: r.State, Reason: r.Reason, Since: r.Since})
+		}
+		if r.Kind == KindDirectory && strings.HasPrefix(r.Reason, ReasonUsedAsFound) {
+			out.Found = append(out.Found, NodeDirectory{Module: r.Module, Resource: r.Resource, Path: r.Target,
+				Reason: r.Reason, Since: r.Since})
+		}
+	}
+	sort.Slice(out.Relogin, func(i, k int) bool {
+		return out.Relogin[i].Account+out.Relogin[i].Module < out.Relogin[k].Account+out.Relogin[k].Module
+	})
+	sort.Slice(out.Found, func(i, k int) bool { return out.Found[i].Path < out.Found[k].Path })
+	sort.Slice(out.Root, func(i, k int) bool {
+		return out.Root[i].Module+out.Root[i].Resource < out.Root[k].Module+out.Root[k].Resource
+	})
+	return out
+}
+
+// HealthStore is where a node's report is kept: its own key of HealthBucket.
+type HealthStore interface {
+	// Get is the key's value, nil when it has none.
+	Get(ctx context.Context, key string) ([]byte, error)
+	Put(ctx context.Context, key string, value []byte) error
+}
+
+// healthStore binds HealthBucket over the link open now: bound, never created.
+func (l *natsLink) healthStore() (HealthStore, error) {
+	kv, err := l.js.KeyValue(HealthBucket)
+	if err != nil {
+		return nil, fmt.Errorf("the node-engine's state %s cannot be bound (it is created from the node-engine's "+
+			"manifest; written again once it is): %w", HealthBucket, err)
+	}
+	return natsHealth{kv}, nil
+}
+
+type natsHealth struct{ kv nats.KeyValue }
+
+func (n natsHealth) Get(_ context.Context, key string) ([]byte, error) {
+	e, err := n.kv.Get(key)
+	if errors.Is(err, nats.ErrKeyNotFound) {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+	return e.Value(), nil
+}
+
+func (n natsHealth) Put(_ context.Context, key string, value []byte) error {
+	_, err := n.kv.Put(key, value)
+	return err
+}
+
+// WriteNodeHealth writes this node's report to its key when it says something other than the key holds, and says
+// whether it wrote. The key is read before the first write of a run, so a restart that finds the same report writes
+// nothing; a store that cannot be bound or written is an error, and the next look tries again.
+func (q *Session) WriteNodeHealth(ctx context.Context, h NodeHealth) (bool, error) {
+	q.init()
+	q.mu.Lock()
+	bus := q.bus
+	q.mu.Unlock()
+	l, ok := bus.(interface{ healthStore() (HealthStore, error) })
+	if bus == nil || !ok {
+		return false, ErrNoLink
+	}
+	store, err := l.healthStore()
+	if err != nil {
+		return false, err
+	}
+	return writeNodeHealth(ctx, store, &q.healthWritten, h, time.Now)
+}
+
+// writeNodeHealth is WriteNodeHealth over a store: last is the report last written or read, nil before the first.
+func writeNodeHealth(ctx context.Context, store HealthStore, last **NodeHealth, h NodeHealth, now func() time.Time) (bool, error) {
+	if *last == nil {
+		raw, err := store.Get(ctx, h.Node)
+		if err != nil {
+			return false, fmt.Errorf("the health report of %s cannot be read: %w", h.Node, err)
+		}
+		if raw != nil {
+			if was, err := delivery.DecodeNodeHealth(raw); err == nil {
+				*last = &was
+			}
+		}
+	}
+	if *last != nil && delivery.SameNodeHealth(**last, h) {
+		return false, nil
+	}
+	h.At = now().UTC()
+	raw, err := delivery.EncodeNodeHealth(h)
+	if err != nil {
+		return false, err
+	}
+	if err := store.Put(ctx, h.Node, raw); err != nil {
+		return false, fmt.Errorf("the health report of %s cannot be written: %w", h.Node, err)
+	}
+	*last = &h
+	return true, nil
+}

internal/link/record.go

@@ -23,6 +23,8 @@ type RecordKeys struct {
 	Certificate string
 	// Authority is the mesh's own certificate as this machine last applied it (public).
 	Authority string
+	// Trusts is what this machine trusts a mesh signature from now (delivery.Trusts, ADR 0550 §2).
+	Trusts []string
 }
 
 // recordOf is the node's record from one facts report and its keys; nil for a report that carries no profile (one that
@@ -45,7 +47,7 @@ func recordOf(node string, r Report, keys RecordKeys) *delivery.NodeRecord {
 		return nil
 	}
 	rec := &delivery.NodeRecord{V: delivery.Version, Node: node, TunnelKey: keys.TunnelKey, SealingKey: keys.SealingKey,
-		ServingKey: keys.ServingKey, Certificate: keys.Certificate, Authority: keys.Authority}
+		ServingKey: keys.ServingKey, Certificate: keys.Certificate, Authority: keys.Authority, Trusts: keys.Trusts}
 	for _, c := range p.Capabilities {
 		if c.Present && c.Name != "" {
 			rec.Capabilities = append(rec.Capabilities, c.Name)

internal/link/run.go

@@ -7,6 +7,8 @@ import (
 	"errors"
 	"fmt"
 	"time"
+
+	meshasks "git.novox.be/novox/mesh-sdk/go/asks"
 )
 
 // Membership is what a node needs to reach its mesh again, held by the caller.
@@ -185,6 +187,12 @@ func serve(ctx context.Context, link Link, m Membership, queue *Session, say Ann
 	}
 	// And the controller asking this node to hand a directory used as found to the mesh (novox/hq issue
 	// 356), answered on the link the question came over.
+	// Every signed ask is verified with the key trusted at that ask, none after the lease write (ADR 0563 §7).
+	if f, ok := link.(interface {
+		FollowSigner(func() ed25519.PublicKey)
+	}); ok && queue.ControllerKey != nil {
+		f.FollowSigner(queue.ControllerKey)
+	}
 	if h, ok := link.(HandOvers); ok {
 		h.HearHandOvers(queue.HandOver)
 	}
@@ -200,6 +208,19 @@ func serve(ctx context.Context, link Link, m Membership, queue *Session, say Ann
 	if s, ok := link.(AccessActs); ok {
 		s.HearAccessActs(queue.AccessAct)
 	}
+	// And its node seat, node-engine, with the operator's answers to its own asks (novox/hq ADR 0563): served on this
+	// link, and what was answered while no link was open caught up from the router's records.
+	if queue.Acts != nil {
+		if s, ok := link.(EngineSeats); ok {
+			s.ServeEngineSeat(queue.Acts.Call)
+		}
+		if a, ok := link.(OperatorAsks); ok {
+			if err := a.HearWarrants(meshasks.EngineAsker(m.Node), queue.Acts.Heard); err != nil {
+				say("cannot hear the operator's answers to this engine's asks: " + err.Error())
+			}
+			go queue.Acts.Reconcile()
+		}
+	}
 	// And asking to move a value sealed to this machine into the vault (design 57's V3, issue 676).
 	if s, ok := link.(MoveSecrets); ok {
 		s.HearMoveSecrets(queue.MoveSecret)

internal/link/session.go

@@ -2,12 +2,14 @@ package link
 
 import (
 	"context"
+	"crypto/ed25519"
 	"encoding/json"
 	"errors"
 	"fmt"
 	"sync"
 	"time"
 
+	stdio "git.novox.be/novox/mesh-sdk/go"
 	"git.novox.be/novox/mesh-sdk/go/health"
 )
 
@@ -47,6 +49,12 @@ type Session struct {
 	// MoveSecret moves one value sealed to this machine into the vault, asked by the controller during the move of
 	// the secrets (design 57's V3, issue 676). Nil answers every such ask with a refusal.
 	MoveSecret MoveSecretFunc
+	// ControllerKey is the controller's key as the engine trusts it now: nil once its lease is handed away (novox/hq
+	// ADR 0563 §7). Each link verifies every signed ask with it, read per ask; nil ControllerKey keeps the membership's.
+	ControllerKey func() ed25519.PublicKey
+	// Acts is the node seat node-engine this engine holds (novox/hq ADR 0563): served on every link, and its asks to the
+	// operator asked and heard over it. Nil serves no seat.
+	Acts *HandActs
 	// Keys reads the node's public keys and its certificate for its record (ADR 0555 §3), at each facts report; nil writes
 	// no record.
 	Keys    func() RecordKeys
@@ -78,6 +86,9 @@ type Session struct {
 
 	// haves is what this node-engine writes beside its facts (novox/hq ADR 0429 §4, issue 1132).
 	haves haveState
+	// healthWritten is this node's health report as last written or read (WriteNodeHealth): the health loop alone
+	// writes it, one look at a time.
+	healthWritten *NodeHealth
 }
 
 func (q *Session) init() {
@@ -337,3 +348,49 @@ func (q *Session) AskSeat(ctx context.Context, seat, verb string, args any, with
 	}
 	return env.Result, nil
 }
+
+// PublishAsk publishes an ask or a cancel to the operator's router over the link open now (novox/hq ADR 0563 §3).
+func (q *Session) PublishAsk(subject string, body any, id string) error {
+	asking, err := q.operatorAsks()
+	if err != nil {
+		return err
+	}
+	return asking.PublishAsk(subject, body, id)
+}
+
+// RouterRecord reads one key of the router's records over the link open now.
+func (q *Session) RouterRecord(key string) (*stdio.StateEntry, error) {
+	asking, err := q.operatorAsks()
+	if err != nil {
+		return nil, err
+	}
+	return asking.RouterRecord(key)
+}
+
+// SayEngine says one of the node seat's events over the link open now; with none open it is not said.
+func (q *Session) SayEngine(event string, body any) {
+	q.init()
+	q.mu.Lock()
+	bus := q.bus
+	q.mu.Unlock()
+	if sayer, ok := bus.(interface{ SayEngine(string, any) error }); ok {
+		if err := sayer.SayEngine(event, body); err != nil {
+			q.Say("could not say the node seat's " + event + ": " + err.Error())
+		}
+	}
+}
+
+func (q *Session) operatorAsks() (OperatorAsks, error) {
+	q.init()
+	q.mu.Lock()
+	bus := q.bus
+	q.mu.Unlock()
+	if bus == nil {
+		return nil, fmt.Errorf("%w: this machine has no link to the bus open now", ErrNotAsked)
+	}
+	asking, ok := bus.(OperatorAsks)
+	if !ok {
+		return nil, errNoAsking
+	}
+	return asking, nil
+}

internal/link/setuid_search_test.go

@@ -57,4 +57,82 @@ func TestASetuidSearchAskIsBelievedOnlySignedForThisNodeAndOnce(t *testing.T) {
 	if a := AnswerSetuidSearch(check, nil, body); a.Refused == "" {
 		t.Fatalf("no handler: %+v", a)
 	}
+	// 774 (ADR 0563 §2): the node seat's setuid-search starts none while one runs, at most one in any hour, naming when the
+	// next may start, and records who asked.
+	t.Run("the node seat's search is bounded", func(t *testing.T) {
+		at, running, started := now, false, 0
+		h := &HandActs{Node: "n1", State: &MemState{}, Now: func() time.Time { return at },
+			Searching:    func() bool { return running },
+			SetuidSearch: func(by string) (string, error) { started++; return "a new search starts", nil }}
+		for _, row := range []struct {
+			name    string
+			after   time.Duration
+			running bool
+			refused string
+			started int
+		}{
+			{name: "one runs", running: true, refused: "runs on this machine now", started: 0},
+			{name: "the first", started: 1},
+			{name: "within the hour", after: 59 * time.Minute, refused: "the next may start at 2026-10-10T03:00:00Z", started: 1},
+			{name: "after the hour", after: time.Hour + time.Second, started: 2},
+		} {
+			at, running = now.Add(row.after), row.running
+			_, err := h.Call(EngineCall{Verb: ActSetuidSearch, Caller: "ace.node-tools"})
+			if (row.refused == "") != (err == nil) || (err != nil && !strings.Contains(err.Error(), row.refused)) || started != row.started {
+				t.Errorf("%s: %v, %d started", row.name, err, started)
+			}
+		}
+		acts, _ := h.Acts(1)
+		if got := acts.(map[string]any)["acts"].([]HandAct); len(got) != 1 || got[0].Caller != "ace.node-tools" || got[0].State != HandDone {
+			t.Errorf("the last search is recorded as %+v", got)
+		}
+		// The bound is kept in a key of its own (rev-l3 round 1): two hundred judgements before a search, or the acts
+		// gone from the record, never let a second search start within the hour.
+		h.JudgeDirectories = func(string) (string, error) { return "judged", nil }
+		for range 200 {
+			if _, err := h.Call(EngineCall{Verb: ActJudgeDirectories, Caller: "ace.node-tools"}); err != nil {
+				t.Fatal(err)
+			}
+		}
+		at = now.Add(time.Hour + 2*time.Minute)
+		if _, err := h.Call(EngineCall{Verb: ActSetuidSearch, Caller: "ace.node-tools"}); err == nil || !strings.Contains(err.Error(), "the next may start") {
+			t.Errorf("a search after two hundred judgements: %v", err)
+		}
+		keys, _ := h.State.Keys("act.")
+		for _, k := range keys {
+			_ = h.State.Delete(k)
+		}
+		if _, err := h.Call(EngineCall{Verb: ActSetuidSearch, Caller: "ace.node-tools"}); err == nil || !strings.Contains(err.Error(), "the next may start") || started != 2 {
+			t.Errorf("a search with the acts gone: %v, %d started", err, started)
+		}
+		// rev-l3 round 2 (ADR 0563 §2, a wrong caller gains nothing): judgements and refused searches, which any caller
+		// may ask, keep one rolling key of the node's, so ten thousand of them write a bounded number of bytes and add no
+		// key to the bucket every node shares.
+		keysNow := func() (int, int) {
+			all, _ := h.State.Keys("")
+			size := 0
+			for _, k := range all {
+				if e, _ := h.State.Get(k); e != nil {
+					size += len(e.Value)
+				}
+			}
+			return len(all), size
+		}
+		_, _ = h.Call(EngineCall{Verb: ActJudgeDirectories, Caller: "unproven"})
+		keysBefore, _ := keysNow()
+		for i := range 10000 {
+			verb := ActJudgeDirectories
+			if i%10 == 0 {
+				verb = ActSetuidSearch
+			}
+			_, _ = h.Call(EngineCall{Verb: verb, Caller: "unproven"})
+		}
+		if n, size := keysNow(); n != keysBefore || size > 64<<10 {
+			t.Errorf("ten thousand judgements and refused searches left %d keys (was %d) of %d bytes", n, keysBefore, size)
+		}
+		listed, _ := h.Acts(0)
+		if got := listed.(map[string]any)["acts"].([]HandAct); len(got) == 0 || got[0].Caller != "unproven" {
+			t.Errorf("acts does not show the latest judgement first: %d", len(got))
+		}
+	})
 }

internal/network/network.go

@@ -32,6 +32,7 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"slices"
 	"sort"
 	"strconv"
 	"strings"
@@ -94,6 +95,18 @@ type Finding struct {
 	Writer string
 	// Toward is what the failure points at: TowardHub, or each resolver's address that failed.
 	Toward []string
+	// Peers is, for the tunnel, each peer of the mesh's interface and whether it was seen (Peer).
+	Peers []Peer
+}
+
+// Peer is one peer of the mesh's tunnel as this machine sees it: its public key, the addresses it is allowed, and
+// whether it handshook within StaleHandshake. What the watchman reads to tell a machine nobody reaches from one whose
+// tunnel alone is down (network-unreachable). Seen, not the handshake's time: the time moves every two minutes, the
+// fact only when a peer comes or goes.
+type Peer struct {
+	Key       string   `json:"key"`
+	Addresses []string `json:"addresses,omitempty"`
+	Seen      bool     `json:"seen"`
 }
 
 // Part is one part's state, as the statement says it.
@@ -115,6 +128,8 @@ type Statement struct {
 	Since time.Time `json:"since"`
 	At    time.Time `json:"at"`
 	Parts []Part    `json:"parts"`
+	// Peers are the tunnel's peers on the last look that read them, sorted by key; nil where the tunnel is not read.
+	Peers []Peer `json:"peers,omitempty"`
 }
 
 // Machine is what a look reads, replaced in tests.
@@ -266,6 +281,9 @@ func (j *Judge) Look(ctx context.Context) (Statement, bool) {
 		changed = true
 	}
 	st.State, st.Since = worst, j.overall.since
+	// The tunnel's peers as this look read them; a peer seen or lost is a change of its own (network-unreachable).
+	st.Peers = findings[PartTunnel].Peers
+	changed = changed || !samePeers(j.said.Peers, st.Peers)
 	j.said = st
 	return st, changed
 }
@@ -435,14 +453,22 @@ func (j *Judge) lookTunnel(ctx context.Context, now time.Time) Finding {
 		}
 	}
 	hub := ""
+	allowed := map[string][]string{}
 	for _, line := range strings.Split(ips, "\n") {
 		f := strings.Fields(line)
 		for _, prefix := range f[min(1, len(f)):] {
+			allowed[f[0]] = append(allowed[f[0]], prefix)
 			if _, bits, ok := strings.Cut(prefix, "/"); ok && bits != "32" && bits != "128" {
 				hub = f[0]
 			}
 		}
 	}
+	peers := make([]Peer, 0, len(handshakes))
+	for key, at := range handshakes {
+		peers = append(peers, Peer{Key: key, Addresses: allowed[key], Seen: at > 0 && now.Sub(time.Unix(at, 0)) <= StaleHandshake})
+	}
+	sort.Slice(peers, func(i, k int) bool { return peers[i].Key < peers[k].Key })
+	found := func(f Finding) Finding { f.Peers = peers; return f }
 	age := func(at int64) string {
 		if at == 0 {
 			return "never"
@@ -452,23 +478,36 @@ func (j *Judge) lookTunnel(ctx context.Context, now time.Time) Finding {
 	if hub != "" {
 		at := handshakes[hub]
 		if at > 0 && now.Sub(time.Unix(at, 0)) <= StaleHandshake {
-			return Finding{OK: true}
+			return found(Finding{OK: true})
 		}
-		return Finding{Reason: "the tunnel to the hub has not handshaken for over five minutes",
-			Said: fmt.Sprintf("%s's newest handshake with the hub was %s", Interface, age(at)), Toward: []string{TowardHub}}
+		return found(Finding{Reason: "the tunnel to the hub has not handshaken for over five minutes",
+			Said: fmt.Sprintf("%s's newest handshake with the hub was %s", Interface, age(at)), Toward: []string{TowardHub}})
 	}
 	if len(handshakes) == 0 {
-		return Finding{OK: true}
+		return found(Finding{OK: true})
 	}
 	var newest int64
 	for _, at := range handshakes {
 		newest = max(newest, at)
 	}
 	if newest > 0 && now.Sub(time.Unix(newest, 0)) <= StaleHandshake {
-		return Finding{OK: true}
+		return found(Finding{OK: true})
 	}
-	return Finding{Reason: "no machine has handshaken with the hub's tunnel for over five minutes",
-		Said: fmt.Sprintf("%s's newest handshake with any of its %d peers was %s", Interface, len(handshakes), age(newest))}
+	return found(Finding{Reason: "no machine has handshaken with the hub's tunnel for over five minutes",
+		Said: fmt.Sprintf("%s's newest handshake with any of its %d peers was %s", Interface, len(handshakes), age(newest))})
+}
+
+// samePeers says two looks saw the same peers, each seen or not alike.
+func samePeers(a, b []Peer) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i := range a {
+		if a[i].Key != b[i].Key || a[i].Seen != b[i].Seen || !slices.Equal(a[i].Addresses, b[i].Addresses) {
+			return false
+		}
+	}
+	return true
 }
 
 func (j *Judge) lookBus() Finding {

internal/network/network_test.go

@@ -302,9 +302,27 @@ func TestOnTheHubAnyFreshPeerIsAHealthyTunnel(t *testing.T) {
 	f.hs = "A=\t" + itoa(f.now.Add(-time.Hour).Unix()) + "\nB=\t" + itoa(f.now.Unix()) + "\nC=\t0\n"
 	f.ips = "A=\t10.10.0.2/32\nB=\t10.10.0.3/32\nC=\t10.10.0.4/32\n"
 	j := f.judge(t)
-	if st := f.look(t, j); st.State != Healthy {
+	st := f.look(t, j)
+	if st.State != Healthy {
 		t.Fatalf("the hub with one fresh peer is %+v", st.Parts)
 	}
+	// Each peer and whether it was seen within five minutes, for the watchman's network-unreachable (issue 774); a
+	// peer seen again is a change, a handshake renewed alone is not.
+	want := []Peer{{Key: "A=", Addresses: []string{"10.10.0.2/32"}}, {Key: "B=", Addresses: []string{"10.10.0.3/32"}, Seen: true},
+		{Key: "C=", Addresses: []string{"10.10.0.4/32"}}}
+	if !samePeers(st.Peers, want) {
+		t.Fatalf("the peers are %+v", st.Peers)
+	}
+	f.hs = "A=\t" + itoa(f.now.Add(LookEvery).Unix()) + "\nB=\t" + itoa(f.now.Add(LookEvery).Unix()) + "\nC=\t0\n"
+	f.now = f.now.Add(LookEvery)
+	if st, changed := j.Look(t.Context()); !changed || !st.Peers[0].Seen {
+		t.Fatalf("a peer seen again is no change: changed %v, %+v", changed, st.Peers)
+	}
+	f.hs = "A=\t" + itoa(f.now.Add(LookEvery).Unix()) + "\nB=\t" + itoa(f.now.Add(LookEvery).Unix()) + "\nC=\t0\n"
+	f.now = f.now.Add(LookEvery)
+	if _, changed := j.Look(t.Context()); changed {
+		t.Fatal("handshakes renewed alone are a change")
+	}
 }
 
 func TestAnUnreadableTunnelIsSaidAndAMissingToolSkipsIt(t *testing.T) {

internal/selfcompose/selfcompose.go

@@ -12,7 +12,9 @@ package selfcompose
 
 import (
 	"context"
+	"crypto/ed25519"
 	"crypto/sha256"
+	"encoding/base64"
 	"encoding/hex"
 	"encoding/json"
 	"errors"
@@ -28,6 +30,7 @@ import (
 	"git.novox.be/novox/mesh-sdk/go/compose"
 	"git.novox.be/novox/mesh-sdk/go/compose/frombus"
 	"git.novox.be/novox/mesh-sdk/go/delivery"
+	"git.novox.be/novox/mesh-sdk/go/overlay"
 
 	"github.com/nats-io/nats.go"
 
@@ -75,6 +78,13 @@ type Env struct {
 	// Fetch reads an archive at a URL in the artifact store: a moved module's templates archive, whose texts its built
 	// manifest carries (issue 1126). Read once per digest. Nil reads none, and a moved module does not compose.
 	Fetch func(ctx context.Context, url string) ([]byte, error)
+	// VaultAuthority is the vault's authority as this node read it from the vault's `signers` (ADR 0550 §2), composed
+	// beside the controller's as the mesh's authority (frombus.SignersReader); "" or nil composes the controller's alone.
+	VaultAuthority func() string
+	// Certify asks the vault's `sign` for this node's own certificate, keeps it and writes the node's record again (ADR
+	// 0550 §2): asked only when a module placed here asks for a certificate and the record holds none from an authority
+	// the node trusts. Nil asks nothing, and such a module stands in, as before.
+	Certify func(ctx context.Context) error
 }
 
 // VaultSecretChanged is the vault's event that a secret changed: a name and its generation, never a value.
@@ -99,6 +109,8 @@ type Composer struct {
 	// sealedOwn is each own secret's sealed value as first handed, by module/name and generation: a value sealed again
 	// is other bytes, so the one first had is kept while the generation stands, and the composition stays the same.
 	sealedOwn map[string]ownSealed
+	// certified is the serving key a certificate was last asked for successfully, so it is asked once per key.
+	certified string
 	said      string
 	refusal   string
 	// held is what the composer's last pass held: each module refused alone, and the node's own ("node") when it could
@@ -411,6 +423,24 @@ func (c *Composer) takeModuleHave(u agent.Update) bool {
 }
 
 // inOwnOf is, of the modules p places, those the node runs inside its own composition (c.inOwn), sorted; c.mu held.
+// Machines is, from the placements this composer holds, each node by its address on the private network, and the hub's
+// node: what names the machine a failing network part points at (delivery.NetworkPart.Targets, issue 774). Empty
+// before any placement is read.
+func (c *Composer) Machines() (byAddress map[string]string, hub string) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	byAddress = map[string]string{}
+	for node, p := range c.placements {
+		if a, _, _ := strings.Cut(p.Decided.Address, "/"); a != "" {
+			byAddress[a] = node
+		}
+		if p.Decided.Hub {
+			hub = node
+		}
+	}
+	return byAddress, hub
+}
+
 func (c *Composer) inOwnOf(p delivery.Placement) []string {
 	var out []string
 	for _, m := range p.Modules {
@@ -501,6 +531,8 @@ func (c *Composer) compose(ctx context.Context) []agent.Update {
 	if c.env.Running != nil {
 		running = c.env.Running()
 	}
+	// Its own certificate, asked of the vault when a module here asks for one and the record holds none it trusts.
+	c.certifyIfWanted(ctx, r, own)
 	scope := frombus.Scope{Node: c.env.Node, KeptAt: kept, InOwn: inOwn, Running: running}
 	missed := c.missed.Load()
 	compositions, _, held, err := frombus.Compose(ctx, r, c.env.Mesh, scope, fps)
@@ -743,9 +775,93 @@ func (c *Composer) Policy(ctx context.Context, module string) string {
 	return policy
 }
 
+// HoldsData says whether a module's manifest declares data (catalogue.Manifest.DataItems), as a composition's Data says
+// it, and whether the manifest could be read: the agent's Data for what runs of a module from the kept declaration
+// (agent.Env.HoldsData, issue 924).
+func (c *Composer) HoldsData(ctx context.Context, module string) (data, known bool) {
+	c.mu.Lock()
+	m, ok := c.modules[module]
+	c.mu.Unlock()
+	if !ok || m.Manifest == "" {
+		return false, false
+	}
+	raw, err := reader{c: c}.Manifest(ctx, m.Manifest)
+	if err != nil {
+		return false, false
+	}
+	parsed, err := catalogue.ParseManifestForInputs(raw)
+	if err != nil {
+		return false, false
+	}
+	return len(parsed.DataItems()) > 0, true
+}
+
 // reader is the composer's view of the bus as frombus reads it.
 type reader struct{ c *Composer }
 
+// VaultAuthority is the vault's authority the node follows (frombus.SignersReader).
+func (r reader) VaultAuthority(context.Context) string {
+	if r.c.env.VaultAuthority == nil {
+		return ""
+	}
+	return r.c.env.VaultAuthority()
+}
+
+var _ frombus.SignersReader = reader{}
+
+// certificateWanted says whether a module the placement p puts on this node asks for a certificate for the machine's
+// internal name (its manifest's `certificate`), read from the indexer's manifests; a manifest that cannot be read is
+// taken as asking none, and the composition says what it misses.
+func (c *Composer) certificateWanted(ctx context.Context, r reader, p delivery.Placement) bool {
+	for _, m := range p.Modules {
+		c.mu.Lock()
+		digest := c.modules[m.Module].Manifest
+		c.mu.Unlock()
+		if digest == "" {
+			continue
+		}
+		raw, err := r.Manifest(ctx, digest)
+		if err != nil {
+			continue
+		}
+		if parsed, err := catalogue.ParseManifestForInputs(raw); err == nil && parsed.Certificate != nil {
+			return true
+		}
+	}
+	return false
+}
+
+// certifyIfWanted asks Certify once per serving key when a module placed here asks for a certificate and this node's
+// record holds none for its internal name and serving key from an authority it trusts (the one it holds, or the vault's).
+func (c *Composer) certifyIfWanted(ctx context.Context, r reader, p delivery.Placement) {
+	if c.env.Certify == nil || !c.certificateWanted(ctx, r, p) {
+		return
+	}
+	c.mu.Lock()
+	rec, ok := c.records[c.env.Node]
+	asked := c.certified
+	c.mu.Unlock()
+	if !ok || rec.ServingKey == "" || asked == rec.ServingKey {
+		return
+	}
+	key, err := base64.StdEncoding.DecodeString(rec.ServingKey)
+	if err != nil || len(key) != ed25519.PublicKeySize {
+		return
+	}
+	trusted := []string{rec.Authority, r.VaultAuthority(ctx)}
+	if rec.Certificate != "" && delivery.CheckNodeCertificate(rec.Certificate, trusted, overlay.InternalName(c.env.Node),
+		ed25519.PublicKey(key), time.Now()) == nil {
+		return
+	}
+	if err := c.env.Certify(ctx); err != nil {
+		c.sayOnce(fmt.Sprintf("a module here asks for a certificate, and the vault's sign gave none: %v", err))
+		return
+	}
+	c.mu.Lock()
+	c.certified = rec.ServingKey
+	c.mu.Unlock()
+}
+
 func (r reader) Placements(context.Context) (map[string]delivery.Placement, error) {
 	r.c.mu.Lock()
 	defer r.c.mu.Unlock()

internal/selfcompose/selfcompose_test.go

@@ -3,6 +3,7 @@ package selfcompose
 import (
 	"context"
 	"crypto/sha256"
+	"encoding/base64"
 	"encoding/hex"
 	"encoding/json"
 	"fmt"
@@ -315,9 +316,9 @@ func TestTheNodeComposesItsWantsFromTheBus(t *testing.T) {
 	}
 	// Issue 1126, the applying path (review of the seed): one module's own refusal holds that module alone. On novox,
 	// de-spiegel's unset route names (its manifest at the indexer's commit e25e1beb, captured) refused the whole node and
-	// marked all its modules not composed. Now lemurs is handed; de-spiegel is held, and proxy with it, which receives its
-	// routes: what was handed of de-spiegel stays handed, so the node keeps running it, and the agent is told those two
-	// alone, de-spiegel in its config form's words.
+	// marked all its modules not composed. Now lemurs and proxy are handed; de-spiegel is held alone (issue 1960: a hold
+	// never spreads to proxy, which composes without its routes, nor to its smtp provider): what was handed of de-spiegel
+	// stays handed, so the node keeps running it, and the agent is told it alone, in its config form's words.
 	spiegel, err := os.ReadFile("testdata/de-spiegel-e25e1beb.module.json")
 	if err != nil {
 		t.Fatal(err)
@@ -353,15 +354,17 @@ func TestTheNodeComposesItsWantsFromTheBus(t *testing.T) {
 	if u, ok := handed3[lemursKey3]; !ok || u.Deleted {
 		t.Errorf("lemurs, which composes, is not handed beside de-spiegel's refusal: %v (told %q)", handed3, *told)
 	}
-	if u, ok := handed3[proxyKey]; ok {
-		t.Errorf("proxy is handed without held de-spiegel's routes: %+v", u)
+	// Issue 1960: a hold never spreads. proxy is handed, composed without held de-spiegel's routes, which do not compose.
+	if u, ok := handed3[proxyKey]; !ok || u.Deleted {
+		t.Errorf("proxy is not handed beside held de-spiegel: %v (told %q)", handed3, *told)
 	}
 	if u, ok := handed3[spiegelKey]; ok {
 		t.Errorf("held de-spiegel is handed %+v, want what was handed of it kept", u)
 	}
 	if len(*told) != 1 || !strings.HasPrefix((*told)[0], "held de-spiegel: ") || !strings.Contains((*told)[0], "${config:praktijk-name}") ||
-		!strings.Contains((*told)[0], "held proxy: ") || strings.Contains((*told)[0], "held lemurs") {
-		t.Errorf("the agent was told %q, want de-spiegel held in its config form's words, and proxy", *told)
+		!strings.Contains((*told)[0], "without what it contributes to route") || strings.Contains((*told)[0], "held proxy") ||
+		strings.Contains((*told)[0], "held lemurs") {
+		t.Errorf("the agent was told %q, want de-spiegel held alone, in its config form's words, without its routes", *told)
 	}
 
 	// A read the bus did not answer, timed out or not, is tried again later; the run's own end and a refusal are not.
@@ -1219,6 +1222,32 @@ func TestTheNodeComposesItsWantsFromTheBus(t *testing.T) {
 		}
 	}
 	b.mu.Unlock()
+
+	// L3 s7 (ADR 0550 §2): the node asks the vault for its own certificate only when a module placed here asks for one
+	// and its record holds none from an authority it trusts; once per serving key.
+	certBus := newFakeBus()
+	certAsks := 0
+	certEnv := certBus.env()
+	certEnv.Certify = func(context.Context) error { certAsks++; return nil }
+	certEnv.VaultAuthority = func() string { return "" }
+	cc := New(certEnv)
+	withCert := `{"module":"web","version":"1","certificate":{"into":"/etc/web/tls.crt"}}`
+	cdigest := delivery.ManifestDigest([]byte(withCert))
+	cc.manifests[digest] = []byte(lemurs)
+	cc.manifests[cdigest] = []byte(withCert)
+	cc.modules = map[string]delivery.Module{"lemurs": {Manifest: digest}, "web": {Manifest: cdigest}}
+	cc.records["n1"] = delivery.NodeRecord{Node: "n1", ServingKey: base64.StdEncoding.EncodeToString(make([]byte, 32))}
+	onlyLemurs := delivery.Placement{Node: "n1", Modules: []delivery.PlacedModule{{Module: "lemurs"}}}
+	cc.certifyIfWanted(context.Background(), reader{c: cc}, onlyLemurs)
+	if certAsks != 0 {
+		t.Errorf("no module asks for a certificate, and the vault was asked %d times", certAsks)
+	}
+	withWeb := delivery.Placement{Node: "n1", Modules: []delivery.PlacedModule{{Module: "lemurs"}, {Module: "web"}}}
+	cc.certifyIfWanted(context.Background(), reader{c: cc}, withWeb)
+	cc.certifyIfWanted(context.Background(), reader{c: cc}, withWeb)
+	if certAsks != 1 {
+		t.Errorf("a module asks for a certificate: the vault was asked %d times, want once", certAsks)
+	}
 }
 
 // patternBus is a bus whose every watch gets the updates of its bucket matching its pattern, as the bus's own watches

module.json

@@ -17,6 +17,15 @@
   "consumes": [
     "restic.backed-up"
   ],
+  "state": [
+    {
+      "name": "acts",
+      "ttl-seconds": 7776000
+    },
+    {
+      "name": "health"
+    }
+  ],
   "config": {
     "operator-signers": {
       "type": "string",

packaging/operator_keys_test.go

@@ -68,4 +68,16 @@ func TestTheManifestConsumesTheBackupEvent(t *testing.T) {
 	if len(m.Consumes) != 1 || m.Consumes[0] != "restic.backed-up" {
 		t.Fatalf("consumes %v", m.Consumes)
 	}
+	// 774 (ADR 0563 §2, §3): the acts of the node seat and the engine's own asks are its declared state acts, the bucket
+	// mesh-host_acts the grants part creates and each node's engine writes under its own keys.
+	parsed, err := catalogue.ParseManifest(raw)
+	if err != nil {
+		t.Fatal(err)
+	}
+	// 774 (the alert table): beside it the state health, one key per node, the node's own health report, kept until
+	// written again (no TTL: a node that stops writing keeps its last word, which the watchman reads with its time).
+	if len(parsed.State) != 2 || parsed.State[0].Name != "acts" || parsed.State[0].TTLSeconds != 90*24*60*60 ||
+		parsed.State[1].Name != "health" || parsed.State[1].TTLSeconds != 0 {
+		t.Fatalf("the manifest declares the state %+v", parsed.State)
+	}
 }