diff --git a/go/catalogue/declaration.go b/go/catalogue/declaration.go
index 6a96e6e..6389454 100644
--- a/go/catalogue/declaration.go
+++ b/go/catalogue/declaration.go
@@ -700,13 +700,7 @@ func (r Resolution) compose(with Rendering, owner map[string]string,
 		handsSecrets := with.Handing(m)
 		for _, name := range sortedKeys(m.OwnSecrets.Plain()) {
 			if handsSecrets {
-				owner := m.SecretsOwner
-				if m.Module == RuntimeModule && r.Account != "" {
-					owner = r.Account
-				}
-				if o := m.OwnSecrets[name].Owner; o != "" {
-					owner = o
-				}
+				owner := r.ownSecretOwner(m, name)
 				first = append(first, ownedBy(owner, map[string]any{
 					"id": NeedID(name), "type": "file", "path": m.OwnSecrets[name].Path, HandedSecretField: name,
 				}))
@@ -718,13 +712,7 @@ func (r Resolution) compose(with Rendering, owner map[string]string,
 				if string(box) == string(ForeseenVaultBox) {
 					*foreseen = append(*foreseen, m.Module+"/"+name)
 				}
-				owner := m.SecretsOwner
-				if m.Module == RuntimeModule && r.Account != "" {
-					owner = r.Account
-				}
-				if o := m.OwnSecrets[name].Owner; o != "" {
-					owner = o
-				}
+				owner := r.ownSecretOwner(m, name)
 				first = append(first, ownedBy(owner, map[string]any{
 					"id": NeedID(name), "type": "file", "path": m.OwnSecrets[name].Path, VaultSealedField: box,
 				}))
@@ -754,14 +742,7 @@ func (r Resolution) compose(with Rendering, owner map[string]string,
 			// the manifest, because a manifest cannot say ${machine:account} safely — a node with no
 			// account has nothing to resolve it to, and then the runtime runs as root and the file
 			// stays root's.
-			owner := m.SecretsOwner
-			if m.Module == RuntimeModule && r.Account != "" {
-				owner = r.Account
-			}
-			if o := m.OwnSecrets[name].Owner; o != "" {
-				owner = o
-			}
-			first = append(first, ownedBy(owner, map[string]any{
+			first = append(first, ownedBy(r.ownSecretOwner(m, name), map[string]any{
 				"id": NeedID(name), "type": "file", "path": m.OwnSecrets[name].Path, "sealed": sealed,
 			}))
 		}
@@ -1677,6 +1658,19 @@ func (r Resolution) provisionsAs(m Manifest) string {
 	return m.SecretsOwner
 }
 
+// ownSecretOwner is who one of a module's own secret files belongs to: the account the manifest names for it, else the
+// runtime's account for the runtime's own credential and for a tools bundle's bus account (ToolsBusSecret; novox/hq ADR
+// 0564 Limits 4), which the runtime runs that bundle as, else the module's secrets-owner (root when none).
+func (r Resolution) ownSecretOwner(m Manifest, name string) string {
+	if o := m.OwnSecrets[name].Owner; o != "" {
+		return o
+	}
+	if r.Account != "" && (m.Module == RuntimeModule || ToolsBusSecret(m, name)) {
+		return r.Account
+	}
+	return m.SecretsOwner
+}
+
 // grantPath is where one consumer's sealed credential lands on the providing machine.
 //
 // Suffixed, so the directory can also hold whatever the module writing it keeps there and so a
diff --git a/go/catalogue/process_bus.go b/go/catalogue/process_bus.go
index c48f11c..3477691 100644
--- a/go/catalogue/process_bus.go
+++ b/go/catalogue/process_bus.go
@@ -85,6 +85,52 @@ func (m Manifest) BusAccounts() []BusAccount {
 	return out
 }
 
+// ToolsBusSecret says name is the own secret a tools bundle's bus account is held in: `broker-<binary>` for a bundle
+// whose bus the manifest declares (ADR 0564 Limits 4). Its file belongs to the runtime's account, which runs the bundle.
+func ToolsBusSecret(m Manifest, name string) bool {
+	for _, a := range m.BusAccounts() {
+		if a.Tools && name == "broker-"+a.ID {
+			return true
+		}
+	}
+	return false
+}
+
+// toolsSecretProblems refuses a tools bundle's bus account secret the runtime's account could not read: it is declared
+// as an own secret `broker-<binary>`, at a path in a directory resource of the module that others may pass through
+// (mode with its last digit odd, such as 0711 or 0755); the file itself is 0600 and the runtime account's.
+func toolsSecretProblems(m Manifest) []string {
+	var problems []string
+	for _, a := range m.BusAccounts() {
+		if !a.Tools {
+			continue
+		}
+		name := "broker-" + a.ID
+		own, declared := m.OwnSecrets.Plain()[name]
+		if !declared {
+			problems = append(problems, fmt.Sprintf("%s's tools bundle %s declares bus and no own secret %s to hold its "+
+				"account in (novox/hq ADR 0564 Limits 4)", m.Module, a.ID, name))
+			continue
+		}
+		dir, _, _ := strings.Cut(strings.TrimPrefix(own.Path, "${dir:"), "}")
+		passable := false
+		for _, r := range m.Resources {
+			if fmt.Sprint(r["type"]) != "directory" || fmt.Sprint(r["id"]) != dir || !strings.HasPrefix(own.Path, "${dir:"+dir+"}/") {
+				continue
+			}
+			mode, _ := r["mode"].(string)
+			passable = mode != "" && strings.ContainsAny(mode[len(mode)-1:], "1357")
+		}
+		if !passable {
+			problems = append(problems, fmt.Sprintf("%s's own secret %s is at %s; a tools bundle's account is read by the "+
+				"node's tool runtime, so it lies in a directory resource of the module that others may pass through "+
+				"(mode 0711 or 0755, `${dir:<id>}/%s`), the file itself the runtime account's, 0600 (novox/hq ADR 0564 "+
+				"Limits 4)", m.Module, name, own.Path, name))
+		}
+	}
+	return problems
+}
+
 // toolsBusProblems is what is wrong with a tools bundle's bus (ADR 0564 Limits 4): a bus on anything but a bundle
 // compiled to a binary the runtime loads, a removal outside the closed set, or a removal beside any other grant or by a
 // module that does not hold mesh-broker. Every other field is judged as a process's.
@@ -191,7 +237,7 @@ func (m Manifest) ProcessBuses() map[string]ProcessBus {
 // §3): the account rule is modelled on RunsAsProblems (seats_declared.go:522-550), and an invoked tool or
 // seat verb's shape on invokeProblems.
 func ProcessBusProblems(m Manifest) []string {
-	problems := toolsBusProblems(m)
+	problems := append(toolsBusProblems(m), toolsSecretProblems(m)...)
 	streams := map[string]bool{}
 	for _, s := range m.Streams {
 		streams[s.Name] = true
diff --git a/go/catalogue/process_bus_test.go b/go/catalogue/process_bus_test.go
index bd59506..cbd9b37 100644
--- a/go/catalogue/process_bus_test.go
+++ b/go/catalogue/process_bus_test.go
@@ -51,10 +51,14 @@ func TestAProcessDeclaresItsBusAndIsAccepted(t *testing.T) {
 	// 1952 S5 (novox/hq ADR 0564 Limits 4; the lead, 2026-10-29): a tools bundle declares its own bus account, read as a
 	// process's, named after its binary and kept through resolution; a removal is from the closed set, alone, and the
 	// bus module's (mesh-broker) alone.
-	tools := func(claims, bus string) string {
-		return `{"module":"nats","version":"1","claims":` + claims + `,"build":{"artifacts":[{"name":"tools","kind":"bundle",` +
+	toolsIn := func(claims, bus, mode string) string {
+		return `{"module":"nats","version":"1","claims":` + claims + `,"own-secrets":{"broker":"${dir:mesh-state}/broker",` +
+			`"broker-nats-tools":"${dir:tools-secret}/broker-nats-tools"},"resources":[{"id":"mesh-state","type":"directory",` +
+			`"mode":"0700","place":"mesh","unknown":"program"},{"id":"tools-secret","type":"directory","mode":"` + mode +
+			`","place":"mesh","unknown":"program"}],"build":{"artifacts":[{"name":"tools","kind":"bundle",` +
 			`"language":"go","system":"arch","from":"cmd/nats-tools","binary":"nats-tools","loads":["nats-tools"],"bus":` + bus + `}]}}`
 	}
+	tools := func(claims, bus string) string { return toolsIn(claims, bus, "0711") }
 	broker := `[{"name":"mesh-broker","scope":"mesh"}]`
 	for _, c := range []struct {
 		name, manifest, refused string
@@ -65,6 +69,9 @@ func TestAProcessDeclaresItsBusAndIsAccepted(t *testing.T) {
 		{name: "another module's tools removing", manifest: tools(`[]`, `{"removes":["mesh-host_acts"]}`), refused: "only the bus module"},
 		{name: "a tools bundle consuming a queue", manifest: tools(broker, `{"queues":["x"]}`), refused: "holds no consumer"},
 		{name: "a process removing", manifest: mailSenderProcessManifest(t, `{"removes":["mesh-host_acts"]}`), refused: "only a tools bundle"},
+		// The runtime's account reads the account's secret: it lies where others may pass (the host agent, 2026-10-29).
+		{name: "a tools secret the runtime cannot reach", manifest: toolsIn(broker, `{"removes":["mesh-host_acts"]}`, "0700"),
+			refused: "others may pass through"},
 	} {
 		m, err := ParseManifest([]byte(c.manifest))
 		if c.refused != "" {
@@ -81,6 +88,12 @@ func TestAProcessDeclaresItsBusAndIsAccepted(t *testing.T) {
 			!strSliceEqual(accounts[0].Bus.Removes, []string{RemovesControllerDeadLetterConsumer, RemovesEngineActs}) {
 			t.Errorf("%s: the accounts are %+v", c.name, accounts)
 		}
+		// Its secret's file is the runtime account's, as the runtime's own credential is; the module's other secrets stay
+		// its own.
+		if (Resolution{Account: "ops"}).ownSecretOwner(m, "broker-nats-tools") != "ops" ||
+			(Resolution{Account: "ops"}).ownSecretOwner(m, "broker") != "" || (Resolution{}).ownSecretOwner(m, "broker-nats-tools") != "" {
+			t.Errorf("%s: the tools secret's owner is %q", c.name, (Resolution{Account: "ops"}).ownSecretOwner(m, "broker-nats-tools"))
+		}
 		// Resolved, the build goes and its bundles keep the bus (build.go).
 		resolved := Manifest{Module: "nats", Bundles: []Bundle{{Name: "tools", Binary: "nats-tools", Bus: m.Build.Artifacts[0].Bus}}}
 		if got := resolved.BusAccounts(); len(got) != 1 || got[0].ID != "nats-tools" {