One runtime principal per node carries every assigned module's tools (hq ADR 0175, to-be 38 WP2.1)

Where the node-tools module is assigned, the machine's bus user list gains one principal of kind
node-tools in place of that module's own: it may subscribe every carried module's tool namespace
and every held seat's verbs on its node, read and follow every membership on its node, call any
tool anywhere, answer what it is asked — and consume nothing, because tools are what it runs.
Every other module keeps its own principal, so a module still serving tools from its container
holds its own credential until it moves.

Named exactly as the module it stands for, so `module issue` and `rollout mint` deliver its
credential through the path a module's already takes, into node-tools' own `broker` secret. The
runtime module's name is one constant in each of the broker and catalogue packages, held to one
string by the agreement test, because a rule turns on it.

cmd/mesh-controller/modules.go

@@ -557,7 +557,7 @@ func issueOnTheNewBus(ctx context.Context, inv *inventory.Inventory, m catalogue
 
 	user := broker.Principal{Kind: broker.KindModule, Node: node, Module: m.Module}.Username()
 	password, err := inv.MintBusPassword(ctx, inventory.BusUser{
-		Username: user, Kind: inventory.BusModule, Node: node, Module: m.Module,
+		Username: user, Kind: busKindOf(m.Module), Node: node, Module: m.Module,
 	})
 	if err != nil {
 		return err
@@ -577,6 +577,16 @@ func issueOnTheNewBus(ctx context.Context, inv *inventory.Inventory, m catalogue
 	return issueWith(ctx, inv, m, node, busAddress, known, reachable, user, password)
 }
 
+// busKindOf is what a module's bus user is recorded as: the node's tool runtime where the module is
+// the runtime (novox/hq ADR 0175), a module otherwise. The username is the same either way — the
+// runtime is issued through this same path — and the kind is what a reader of the records sees.
+func busKindOf(module string) string {
+	if module == catalogue.RuntimeModule {
+		return inventory.BusNodeTools
+	}
+	return inventory.BusModule
+}
+
 // issueWith is the delivery half: the minted password sealed to the machine as the module's broker
 // secret, and the module's consumer created where the bus can be reached. Split from the minting
 // so the move can issue every module against a bus whose address it worked out itself

cmd/mesh-controller/rollout.go

@@ -346,7 +346,9 @@ func rolloutMint(ctx context.Context, again bool) error {
 			}
 			machines++
 
-		case broker.KindModule:
+		case broker.KindModule, broker.KindNodeTools:
+			// The runtime is minted and delivered exactly as a module is (novox/hq ADR 0175): it is
+			// issued as the module it stands for, to that module's `broker` secret.
 			if p.Module == "mesh-controller" {
 				// The control plane is a module too, and its `broker` secret is the old bus's
 				// credential it is still using while this runs. Writing the new bus's blob there
@@ -365,7 +367,7 @@ func rolloutMint(ctx context.Context, again bool) error {
 				skipped++
 				continue
 			}
-			password, err := inv.MintBusPassword(ctx, inventory.BusUser{Username: p.Username(), Kind: inventory.BusModule, Node: p.Node, Module: p.Module})
+			password, err := inv.MintBusPassword(ctx, inventory.BusUser{Username: p.Username(), Kind: busKindOf(p.Module), Node: p.Node, Module: p.Module})
 			if err != nil {
 				return err
 			}

internal/broker/agreement_catalogue_test.go

@@ -234,3 +234,13 @@ func admitsSubject(pattern, subject []string) bool {
 	}
 	return len(pattern) == len(subject)
 }
+
+// The two packages name the runtime module separately — the broker's types stay free of the
+// catalogue's on purpose — so this is what holds them to one string. A rename that reached only one
+// side would compose a runtime principal for a module nobody assigns, silently, and leave the one
+// that is assigned with a module's own grants.
+func TestTheBrokerAndTheCatalogueAgreeOnTheRuntimeModule(t *testing.T) {
+	if RuntimeModule != catalogue.RuntimeModule {
+		t.Fatalf("the broker calls the runtime %q and the catalogue %q", RuntimeModule, catalogue.RuntimeModule)
+	}
+}

internal/broker/nats.go

@@ -34,8 +34,20 @@ const (
 	// authority is a list of tools and nothing else — not control, not declarations, not builds,
 	// and no ability to answer anything, because a person asks.
 	KindPerson Kind = "person"
+	// KindNodeTools is a machine's tool runtime (novox/hq ADR 0175, to-be 38): one process per
+	// node, on the host side, serving every assigned module's tools and every held seat's verbs.
+	// Its authority is the union of what the modules it carries would each have had for their
+	// tools — and nothing of what they consume, because tools are what it runs, not reactions.
+	KindNodeTools Kind = "node-tools"
 )
 
+// RuntimeModule is the module that IS the node's tool runtime (novox/hq ADR 0175). Where it is
+// assigned, the mesh composes one runtime principal for the machine in place of that module's own,
+// and the per-module containers that served tools until then stop being the way tools reach a node.
+// Mirrored in the catalogue package, which the agreement test holds to the same string; one
+// constant, so a rename is one edit and the two packages cannot drift.
+const RuntimeModule = "node-tools"
+
 // Seat is a role on the bus as a principal relates to it: the subjects it accepts, and those it
 // emits (novox/hq ADR 0118, design 29 §5).
 type Seat struct {
@@ -74,6 +86,13 @@ type Principal struct {
 	// a namespace no such module owns. Every service started and the graph stayed empty.
 	Watches []Seat
 
+	// Carries are the modules whose tools this principal serves, for a KindNodeTools principal
+	// (novox/hq ADR 0175): every module assigned to its node, as each declares itself. Its
+	// serving authority is the union of theirs — each module's own tool namespace and each held
+	// seat's verbs on this node — derived from the same declarations the modules' own principals
+	// are, so the runtime can serve nothing a module could not have served for itself.
+	Carries []Declared
+
 	// Invokes are the tools this principal may call, as `<module>.<tool>`; a single `*` is every
 	// tool. A person's whole authority (design 25 §7), and a module's only if its manifest says so
 	// (novox/hq ADR 0152) — the console's does, and nothing else's.
@@ -112,7 +131,10 @@ func (p Principal) Username() string {
 	switch p.Kind {
 	case KindPerson:
 		return "person." + p.Module
-	case KindModule:
+	case KindModule, KindNodeTools:
+		// The runtime is named exactly as the module it stands for would have been: the mesh
+		// issues its credential through the same path a module's takes (`module issue`), and
+		// that path knows the node and the module, not the kind.
 		return p.Node + "." + p.Module
 	case KindNode:
 		return "node." + p.Node
@@ -375,6 +397,48 @@ func PermissionsFor(p Principal) (Permissions, error) {
 				pub = append(pub, seatToolSubject(s, t, "*"))
 			}
 		}
+
+	case KindNodeTools:
+		// **One process serves what every module on the machine would have served for itself**
+		// (novox/hq ADR 0175). Each carried module's whole tool namespace — the same grant that
+		// module's own principal has, for the same reason: the tools a module serves are what its
+		// code answers, and a list here would be a second copy of it. Each held seat's verbs on
+		// this node, as the holder's own principal would be granted them.
+		for _, d := range p.Carries {
+			if !safeSubject.MatchString(d.Module) {
+				return Permissions{}, fmt.Errorf(
+					"%q cannot be part of a subject: a permission is a subject pattern, and this would widen it", d.Module)
+			}
+			own := "mesh.mod." + d.Module
+			sub = append(sub, own+".tool.>")
+			// A tool that emits an event is the module's code and emits under the module's name
+			// (ADR 0042); the runtime carrying that code may publish what the module declared it
+			// emits, and nothing it did not.
+			for _, e := range d.Emits {
+				pub = append(pub, own+".event."+e)
+			}
+			for _, s := range d.Holds {
+				for _, t := range s.Serves {
+					sub = append(sub, seatToolSubject(s, t, p.Node))
+				}
+			}
+		}
+		// Every assigned module's membership on this node (ADR 0160): one per module, read
+		// directly from the stream and followed live. This node's and no other's — the one token
+		// that varies is the module, so the pattern is the machine's own assignments.
+		sub = append(sub, "mesh.assignment."+p.Node+".*")
+		pub = append(pub, "$JS.API.DIRECT.GET."+AssignmentsStream+".mesh.assignment."+p.Node+".*")
+		// And every tool on the mesh (ADR 0175, decision 5): any node may call any tool on any
+		// node, as the console already could — the runtime is the console's serving mode.
+		invoked, err := invokedSubjects([]string{"*"})
+		if err != nil {
+			return Permissions{}, err
+		}
+		pub = append(pub, invoked...)
+		// Nothing about consumers: it consumes nothing. A module's reactions to events are its
+		// own long-lived process, which ADR 0175 leaves where it is; what moves here is tools.
+		sub = unique(sub)
+		pub = unique(pub)
 	}
 
 	if p.Kind == KindPerson {
@@ -382,6 +446,11 @@ func PermissionsFor(p Principal) (Permissions, error) {
 		// consumer, because nothing is delivered to a person — they ask and are answered.
 		sub = append(sub, p.inbox())
 	}
+	if p.Kind == KindNodeTools {
+		// Its reply space, so the answers to what its tools call come back to it. No ack subject
+		// for the same reason a person has none: nothing is delivered to it.
+		sub = append(sub, p.inbox())
+	}
 
 	if p.Kind == KindModule || p.Kind == KindNode || p.Kind == KindController {
 		// Its own reply space, and nothing wider.
@@ -403,7 +472,7 @@ func PermissionsFor(p Principal) (Permissions, error) {
 		// A module answers what it was asked — a tool call reaches it on its own namespace, so the
 		// authority is bounded by having been asked — and so does the controller. A node and a
 		// person are never asked anything, and are granted nothing here.
-		AllowResponses: p.Kind == KindModule || p.Kind == KindController,
+		AllowResponses: p.Kind == KindModule || p.Kind == KindController || p.Kind == KindNodeTools,
 	}, nil
 }
 
@@ -625,6 +694,20 @@ func ComposeAccounts(principals []Principal) (string, error) {
 	return b.String(), nil
 }
 
+// unique is a sorted list with each subject once. Two carried modules holding seats with the same
+// verb, or the runtime module itself carried beside the others, would otherwise write a grant twice
+// — harmless to the server, and noise in a file that is read as the mesh's authority model.
+func unique(values []string) []string {
+	sort.Strings(values)
+	out := values[:0]
+	for i, v := range values {
+		if i == 0 || v != values[i-1] {
+			out = append(out, v)
+		}
+	}
+	return out
+}
+
 func quoted(values []string) string {
 	if len(values) == 0 {
 		return ""

internal/broker/nats_test.go

@@ -371,3 +371,73 @@ func TestAModulePullsItsOwnConsumerAndNoOthers(t *testing.T) {
 		}
 	}
 }
+
+// The runtime's authority is the union of what the modules it carries would have been granted for
+// their tools (novox/hq ADR 0175): every carried module's tool namespace, every held seat's verbs
+// on this node, every module's membership on this node, and a call to anything. Nothing it
+// consumes, because it reacts to nothing.
+func TestTheRuntimeServesTheUnionAndConsumesNothing(t *testing.T) {
+	filter := Seat{Name: "node-packet-filter", Scope: "node", Serves: []string{"rules", "reload"}}
+	p := Principal{Kind: KindNodeTools, Node: "anchor", Module: RuntimeModule, Carries: []Declared{
+		{Module: "nftables", Holds: []Seat{filter}, Serves: []string{"firewall_rules"}},
+		{Module: "zsh", Emits: []string{"shell.opened"}, Consumes: []string{"shop.order.placed"}},
+		{Module: RuntimeModule},
+	}}
+	perms, err := PermissionsFor(p)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, want := range []string{
+		"mesh.mod.nftables.tool.>", "mesh.mod.zsh.tool.>", "mesh.mod." + RuntimeModule + ".tool.>",
+		"mesh.seat.node-packet-filter.tool.rules.anchor", "mesh.seat.node-packet-filter.tool.reload.anchor",
+		"mesh.assignment.anchor.*",
+		"_INBOX.anchor." + RuntimeModule + ".>",
+	} {
+		if !contains(perms.Subscribe, want) {
+			t.Errorf("the runtime may not subscribe %s: %v", want, perms.Subscribe)
+		}
+	}
+	for _, want := range []string{
+		"mesh.mod.*.tool.>", "mesh.seat.*.tool.>",
+		"$JS.API.DIRECT.GET.ASSIGNMENTS.mesh.assignment.anchor.*",
+		"mesh.mod.zsh.event.shell.opened",
+	} {
+		if !contains(perms.Publish, want) {
+			t.Errorf("the runtime may not publish %s: %v", want, perms.Publish)
+		}
+	}
+	// Nothing of what a carried module consumes, and no consumer of its own to ack.
+	for _, s := range perms.Subscribe {
+		if strings.Contains(s, ".event.") || strings.HasPrefix(s, "_DELIVER.") {
+			t.Errorf("the runtime was granted a delivery it has no consumer for: %s", s)
+		}
+	}
+	for _, s := range perms.Publish {
+		if strings.HasPrefix(s, "$JS.ACK.") || strings.Contains(s, "CONSUMER") {
+			t.Errorf("the runtime was granted a consumer's subject and has no consumer: %s", s)
+		}
+	}
+	if !perms.AllowResponses {
+		t.Error("the runtime answers what it is asked, and may not reply")
+	}
+	if _, needed := ConsumerFor(p); needed {
+		t.Error("a consumer would be made for the runtime, which consumes nothing")
+	}
+	// Each subject once: the file is read as the mesh's authority model.
+	seen := map[string]bool{}
+	for _, s := range append(append([]string{}, perms.Subscribe...), perms.Publish...) {
+		if seen[s] {
+			t.Errorf("%s is granted twice", s)
+		}
+		seen[s] = true
+	}
+}
+
+func contains(list []string, want string) bool {
+	for _, s := range list {
+		if s == want {
+			return true
+		}
+	}
+	return false
+}

internal/broker/users.go

@@ -62,13 +62,33 @@ func Users(r Records) ([]Principal, error) {
 
 	for _, node := range sortedCopy(r.Nodes) {
 		out = append(out, Principal{Kind: KindNode, Node: node})
+		// **Where the runtime is assigned, the machine gets one runtime principal in place of the
+		// runtime module's own** (novox/hq ADR 0175, to-be 38). It carries every module on the
+		// node: its serving grants are the union of theirs. Every other module keeps its own
+		// principal — a module still serving tools from its own container holds its own
+		// credential until it moves, and the two serve side by side in the meantime.
+		runtimeHere := false
 		for _, d := range r.Assigned[node] {
+			if d.Module == RuntimeModule {
+				runtimeHere = true
+			}
+		}
+		for _, d := range r.Assigned[node] {
+			if runtimeHere && d.Module == RuntimeModule {
+				continue
+			}
 			out = append(out, Principal{
 				Kind: KindModule, Node: node, Module: d.Module,
 				Emits: d.Emits, Consumes: d.Consumes, Serves: d.Serves,
 				Holds: d.Holds, Uses: d.Uses, Watches: d.Watches, Invokes: d.Invokes,
 			})
 		}
+		if runtimeHere {
+			out = append(out, Principal{
+				Kind: KindNodeTools, Node: node, Module: RuntimeModule,
+				Carries: append([]Declared(nil), r.Assigned[node]...),
+			})
+		}
 	}
 	for _, node := range sortedCopy(r.Enrolling) {
 		out = append(out, Principal{Kind: KindEnrolment, Node: node})

internal/broker/users_test.go

@@ -245,3 +245,54 @@ func TestAUserListIsComposedBeforeAnythingMovesOntoTheBus(t *testing.T) {
 		t.Errorf("the composed list does not contain the machine running the bus")
 	}
 }
+
+// Where the runtime module is assigned, the machine gets one runtime principal in place of the
+// runtime module's own (novox/hq ADR 0175, to-be 38). Every other module keeps its own: a module
+// still serving tools from its own container holds its own credential until it moves.
+func TestTheRuntimeModuleBecomesTheMachinesRuntimePrincipal(t *testing.T) {
+	r := someRecords()
+	r.Assigned["one"] = append(r.Assigned["one"], Declared{Module: RuntimeModule})
+	users, err := Users(r)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var runtime *Principal
+	for i := range users {
+		p := &users[i]
+		if p.Node == "one" && p.Module == RuntimeModule {
+			if p.Kind == KindModule {
+				t.Fatalf("%s on one was composed as an ordinary module beside the runtime", RuntimeModule)
+			}
+			runtime = p
+		}
+	}
+	if runtime == nil || runtime.Kind != KindNodeTools {
+		t.Fatalf("one runs %s and got no runtime principal: %v", RuntimeModule, namesOf(t, r))
+	}
+	if runtime.Username() != "one."+RuntimeModule {
+		t.Errorf("the runtime is named %q; `module issue` names it as the module it stands for", runtime.Username())
+	}
+	carried := map[string]bool{}
+	for _, d := range runtime.Carries {
+		carried[d.Module] = true
+	}
+	if !carried["telegram"] || !carried[RuntimeModule] {
+		t.Errorf("the runtime carries %v; it carries every module on its node", carried)
+	}
+	// And the other node, where the runtime is not assigned, is exactly as before.
+	for _, p := range users {
+		if p.Node == "two" && p.Kind == KindNodeTools {
+			t.Fatal("two runs no runtime and was given a runtime principal")
+		}
+	}
+	// A module serving its own tools beside the runtime keeps its own principal.
+	found := false
+	for _, p := range users {
+		if p.Kind == KindModule && p.Node == "one" && p.Module == "telegram" {
+			found = true
+		}
+	}
+	if !found {
+		t.Error("telegram lost its own principal when the runtime arrived on its node")
+	}
+}

internal/catalogue/runtime.go

@@ -0,0 +1,13 @@
+package catalogue
+
+// The node's tool runtime, as the catalogue knows it (novox/hq ADR 0175, to-be 38).
+//
+// **One module is the runtime.** Where it is assigned, one process per machine serves every assigned
+// module's tools and every held seat's verbs, on the host side, from the bundles each module's build
+// produced — and no module needs a container to reach the bus with its tools. The name is a constant
+// rather than a manifest field because a rule turns on it: the composer places the runtime's process
+// where this module is, and registration refuses the old pattern once this module exists.
+
+// RuntimeModule is the module that is the node's tool runtime. Mirrored in the broker package,
+// which composes a principal of its own for it; the agreement test there holds the two to one string.
+const RuntimeModule = "node-tools"

internal/inventory/bususers.go

@@ -42,6 +42,9 @@ const (
 	BusModule     = "module"
 	BusEnrolment  = "enrolment"
 	BusPerson     = "person"
+	// BusNodeTools is a machine's tool runtime (novox/hq ADR 0175): named like the module it
+	// stands for, recorded as what it is.
+	BusNodeTools = "node-tools"
 )
 
 // MintBusPassword makes a bus password and records its hash under a username, replacing whatever was