Merge pull request 'A refused tool subscription is said, never fatal (hq issue 218)' (#46) from fix/a-refused-seat-subscription-is-not-fatal into main

After the controller stopped granting a mesh seat to claimants that do not hold it, an image built
before the runtime followed its membership still subscribed the seat's subject, and the refusal
ended the process: ace's postgres runtime crash-looped. A subject the grants leave out now costs
that subject only, as an announcement's already did (issue 217).

Dockerfile

@@ -28,6 +28,14 @@ COPY node-tools/package.json ./
 # credential travels no further than here. Development dependencies included: the compiler is one.
 COPY .npmrc ./.npmrc
 RUN npm install --no-audit --no-fund
+# **The SDK this image carries is the one the mesh last published** (novox/hq issue 212). The range in
+# package.json is resolved once and the layer above is cached, so a release reached no toolchain until
+# that file changed. The exact version arrives as a build argument from the SDK module's published
+# package (module.json `build.on`), so a new release is a new argument, this layer runs again — and
+# the planner orders this module after the SDK, so a release rebuilds the toolchain and, after it,
+# every bundle compiled in it (issue 211).
+ARG MESH_SDK=@novox/mesh-sdk@latest
+RUN npm install --no-audit --no-fund "${MESH_SDK}"
 
 # ---- compiling: the runtime's own code built, WITHOUT the credential -------------------------
 FROM ${NODE_BASE} AS compiling
@@ -45,6 +53,9 @@ FROM compiling AS lean
 RUN npm prune --omit=dev
 
 # ---- toolchain: what a TypeScript bundle is compiled in ---------------------------------------
+# The compiler, and esbuild (a development dependency) at /app/node_modules/esbuild: the builder
+# bundles every entrypoint and launcher into one file with it (novox/hq ADR 0193), so a bundle
+# carries what it imports and not this image's node_modules.
 # Beside the compiler, at /app/runtime, what every TypeScript bundle runs with: the production
 # dependencies the SDK and the runtime need, and a package.json saying the compiled files are ES
 # modules. The builder copies this directory whole into a compiled bundle (novox/hq ADR 0188 §5),

module.json

@@ -21,6 +21,11 @@
       {
         "arg": "NODE_BASE",
         "image": "node@sha256:48e4b67d85f87bd551df43704e24d252f56cc5f8e9718841aace50f19948f0f9"
+      },
+      {
+        "arg": "MESH_SDK",
+        "module": "mesh-sdk",
+        "artifact": "lib"
       }
     ]
   },

node-tools/cmd/node-tools/main.go

@@ -0,0 +1,130 @@
+// node-tools — the node's tool runtime, in Go (novox/hq ADR 0175, ADR 0193; to-be 38 WP4d).
+//
+// One process per machine: it connects to the bus on the node's credential, launches every assigned
+// module's tools bundle and serves its tools and its seats' verbs; as the node-tools module — or
+// wherever MESH_CONSOLE_LISTEN says — it is also the console, MCP over HTTP on loopback.
+//
+//	MESH_BROKER_FILE       the credential the mesh sealed to this machine for the runtime
+//	MESH_TOOL_MODULES      <module>=<entrypoint>,… the bundles to launch
+//	MESH_TOOL_ENV          {"<module>": {"<word>": "<value>"}} what each is given (ADR 0192)
+//	MESH_OPERATOR_ACCOUNT  whose machine this is, and MESH_OPERATOR_HOME their home
+//	MESH_CONSOLE_LISTEN    where the console listens, overriding 127.0.0.1:4270
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"log"
+	"math/rand/v2"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"github.com/novox/mesh-tools/node-tools/internal/bus"
+	"github.com/novox/mesh-tools/node-tools/internal/console"
+	"github.com/novox/mesh-tools/node-tools/internal/runtime"
+)
+
+// runtimeModule is the module that is the node's tool runtime; on its credential, serving is also
+// the console.
+const runtimeModule = "node-tools"
+
+// consoleListen is where the console listens when nothing says otherwise.
+const consoleListen = "127.0.0.1:4270"
+
+func main() {
+	log.SetFlags(0)
+	if len(os.Args) > 1 && os.Args[1] != "serve" {
+		fmt.Fprintf(os.Stderr, "node-tools: %q is not a mode; this runtime serves (novox/hq ADR 0193)\n", os.Args[1])
+		os.Exit(2)
+	}
+	cred := credential()
+	conn := connectPatiently(cred)
+
+	served, err := runtime.ServedModulesFrom(os.Getenv(runtime.ToolModules), cred.Module)
+	if err != nil {
+		log.Fatalf("node-tools: %v", err)
+	}
+	envs, err := runtime.TakeToolEnvs()
+	if err != nil {
+		log.Fatalf("node-tools: %v", err)
+	}
+	stop, err := runtime.Run(conn, served, envs, log.Printf)
+	if err != nil {
+		log.Fatalf("node-tools: %v", err)
+	}
+
+	listen := os.Getenv("MESH_CONSOLE_LISTEN")
+	if listen == "" && cred.Module == runtimeModule {
+		listen = consoleListen
+	}
+	var up *console.Listening
+	if listen != "" {
+		node := cred.Node
+		if node == "" {
+			node = "?"
+		}
+		who := node + "." + cred.Module
+		up, err = console.Serve(console.NewSurface(conn, who), listen)
+		if err != nil {
+			log.Fatalf("node-tools: %v", err)
+		}
+		log.Printf("mesh console listening on http://%s/mcp as %s", up.Address, who)
+	}
+
+	signals := make(chan os.Signal, 1)
+	signal.Notify(signals, syscall.SIGTERM, syscall.SIGINT)
+	<-signals
+	stop()
+	if up != nil {
+		_ = up.Close()
+	}
+	conn.Close()
+}
+
+// credential reads the credential the mesh delivered; a missing or unreadable one is a fault of
+// configuration, said and final.
+func credential() bus.Credential {
+	file := os.Getenv("MESH_BROKER_FILE")
+	if file == "" {
+		if url := os.Getenv("MESH_BROKER_URL"); url != "" {
+			return bus.Credential{URL: url, Module: runtimeModule}
+		}
+		fmt.Fprintln(os.Stderr, "node-tools: set MESH_BROKER_FILE (a sealed credential) or MESH_BROKER_URL — there is no broker to reach")
+		os.Exit(1)
+	}
+	raw, err := os.ReadFile(file)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "node-tools: cannot read the broker credential at %s: %v\n", file, err)
+		os.Exit(1)
+	}
+	var cred bus.Credential
+	if err := json.Unmarshal(raw, &cred); err != nil {
+		fmt.Fprintf(os.Stderr, "node-tools: cannot read the broker credential at %s: %v\n", file, err)
+		os.Exit(1)
+	}
+	if cred.URL == "" {
+		fmt.Fprintf(os.Stderr, "node-tools: %s carries no url — it is not a broker credential\n", file)
+		os.Exit(1)
+	}
+	return cred
+}
+
+// connectPatiently retries while the bus is merely not reachable yet — the normal case at startup —
+// and gives up at once on what waiting cannot fix (issue 058).
+func connectPatiently(cred bus.Credential) *bus.Conn {
+	for delay := 2 * time.Second; ; delay = min(delay*2, 30*time.Second) {
+		conn, err := bus.Connect(cred)
+		if err == nil {
+			return conn
+		}
+		if fatal := bus.Fatal(err); fatal != "" {
+			fmt.Fprintf(os.Stderr, "node-tools: %s — waiting will not fix this; giving up\n", fatal)
+			os.Exit(1)
+		}
+		wait := delay + time.Duration(rand.IntN(1000))*time.Millisecond
+		fmt.Fprintf(os.Stderr, "node-tools: the broker is not reachable yet (%v); retrying in %ds\n", err, int(wait.Round(time.Second)/time.Second))
+		time.Sleep(wait)
+	}
+}

node-tools/go.mod

@@ -0,0 +1,15 @@
+module github.com/novox/mesh-tools/node-tools
+
+go 1.26.0
+
+require (
+	github.com/nats-io/nats.go v1.54.0
+	golang.org/x/sys v0.48.0
+)
+
+require (
+	github.com/klauspost/compress v1.20.0 // indirect
+	github.com/nats-io/nkeys v0.4.16 // indirect
+	github.com/nats-io/nuid v1.0.1 // indirect
+	golang.org/x/crypto v0.57.0 // indirect
+)

node-tools/go.sum

@@ -0,0 +1,12 @@
+github.com/klauspost/compress v1.20.0 h1:a3C1ke2ohxFymNlb2HWAHjDeKCI90scRskErZkR0ezA=
+github.com/klauspost/compress v1.20.0/go.mod h1:LUdAzn7YLVvxLpc7y3V1m40wESHTgc1422pwwBSKYuI=
+github.com/nats-io/nats.go v1.54.0 h1:vsXoOxjHp/GmPUN+EcI7uOf/uB+iAP+kEsAFNQN0yzA=
+github.com/nats-io/nats.go v1.54.0/go.mod h1:y+DZoD1oBOYfZTU681eTUiUjI0vbqYGixNVFHcjHJ0k=
+github.com/nats-io/nkeys v0.4.16 h1:rd5oAuLOb8mnAycB0xleuEBNS1pVVnN0fv/FF34Eypg=
+github.com/nats-io/nkeys v0.4.16/go.mod h1:llLgWoI0o4z/Q57q2R1kHfmocyhGV6VG/U18Glg1Afs=
+github.com/nats-io/nuid v1.0.1 h1:5iA8DT8V7q8WK2EScv2padNa/rTESc1KdnPw4TC2paw=
+github.com/nats-io/nuid v1.0.1/go.mod h1:19wcPz3Ph3q0Jbyiqsd0kePYG7A95tJPxeL+1OSON2c=
+golang.org/x/crypto v0.57.0 h1:3ZVCjf8Ggz7zneR/EHRVx68Ctf+2pmIMP2UFhh9cC6M=
+golang.org/x/crypto v0.57.0/go.mod h1:Fdz0i5U6CoizGwLda9DttjSk6qlZo25zYNtR+ycvuZA=
+golang.org/x/sys v0.48.0 h1:bbX/i/6MgT9BVLM9RT1thmxL04yeTAhbEz4SyadbXoo=
+golang.org/x/sys v0.48.0/go.mod h1:hNLxWAXmnKAxqDtdwIYC4bM9oQPEecfsnNMuSxOs3og=

node-tools/internal/announce/announce.go

@@ -0,0 +1,211 @@
+// Package announce answers the NATS services protocol's discovery for what a runtime serves, and
+// gathers the answers (novox/hq ADR 0197).
+//
+// A runtime does not re-serve its tools through a services library: serving is unchanged. It answers
+// `$SRV.PING`, `$SRV.INFO` and `$SRV.STATS` — and the same followed by its service name, and by its
+// name and id — in the format NATS's own tools read, with what it is serving at the moment it is
+// asked. One service per runtime process: the bus admits one reply per request from each responder,
+// so a runtime serving many modules and seats answers once, one endpoint per tool per subject, and
+// says in each endpoint's metadata which module, seat, scope and machine it is.
+package announce
+
+import (
+	"encoding/json"
+	"strings"
+	"time"
+
+	"github.com/nats-io/nats.go/micro"
+
+	"github.com/novox/mesh-tools/node-tools/internal/bus"
+)
+
+// Version is the announced service version (semver, as the protocol requires).
+const Version = "0.1.0"
+
+// Window is how long the console gathers discovery answers: every instance answers one request, and
+// how many will is what is being found out.
+var Window = 750 * time.Millisecond
+
+// Kinds of endpoint.
+const (
+	KindTool = "tool" // a module's own tool
+	KindSeat = "seat" // a seat's verb, served by the module holding it
+)
+
+// Endpoint is one tool served on one subject, as it is announced.
+type Endpoint struct {
+	Kind            string
+	Module          string // the module whose code answers
+	Tool            string // the tool's or the verb's name
+	Seat            string // for a seat's verb
+	Scope           string // "mesh" or "node", for a seat's verb
+	Node            string
+	Description     string
+	Schema          json.RawMessage
+	Interchangeable bool
+	Subject         string
+	Queue           string
+}
+
+// Name is the endpoint's name as the protocol allows it — letters, digits, `-` and `_` — the
+// prefix and the tool joined by `__`; the metadata, not the name, is what identifies it.
+func (e Endpoint) Name() string {
+	prefix := e.Module
+	if e.Kind == KindSeat {
+		prefix = e.Seat
+	}
+	return clean(prefix) + "__" + clean(e.Tool)
+}
+
+func clean(s string) string {
+	var b strings.Builder
+	for _, r := range s {
+		if r == '-' || r == '_' || (r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z') || (r >= '0' && r <= '9') {
+			b.WriteRune(r)
+		} else {
+			b.WriteRune('_')
+		}
+	}
+	return b.String()
+}
+
+func (e Endpoint) info() micro.EndpointInfo {
+	md := map[string]string{
+		"kind": e.Kind, "module": e.Module, "tool": e.Tool, "node": e.Node,
+		"description": e.Description, "interchangeable": boolWord(e.Interchangeable),
+	}
+	schema := strings.TrimSpace(string(e.Schema))
+	if schema == "" || schema == "null" {
+		schema = "{}"
+	}
+	md["schema"] = schema
+	if e.Kind == KindSeat {
+		md["seat"] = e.Seat
+		md["scope"] = e.Scope
+	}
+	return micro.EndpointInfo{Name: e.Name(), Subject: e.Subject, QueueGroup: e.Queue, Metadata: md}
+}
+
+func boolWord(b bool) string {
+	if b {
+		return "true"
+	}
+	return "false"
+}
+
+// Service is who answers: the runtime's name, its instance, and a word about it.
+type Service struct {
+	Name        string
+	ID          string
+	Description string
+	Metadata    map[string]string
+}
+
+func (s Service) identity() micro.ServiceIdentity {
+	md := s.Metadata
+	if md == nil {
+		md = map[string]string{}
+	}
+	return micro.ServiceIdentity{Name: s.Name, ID: s.ID, Version: Version, Metadata: md}
+}
+
+// Info is the info_response for these endpoints.
+func Info(s Service, endpoints []Endpoint) micro.Info {
+	out := micro.Info{ServiceIdentity: s.identity(), Type: micro.InfoResponseType,
+		Description: s.Description, Endpoints: []micro.EndpointInfo{}}
+	for _, e := range endpoints {
+		out.Endpoints = append(out.Endpoints, e.info())
+	}
+	return out
+}
+
+// Serve answers discovery for one service until stopped, asking `current` for its endpoints each
+// time — so what is announced is what is served now, re-served memberships included.
+func Serve(conn *bus.Conn, s Service, current func() []Endpoint) (func(), error) {
+	started := time.Now().UTC()
+	answer := func(subject string, _ []byte) []byte {
+		parts := strings.Split(subject, ".")
+		if len(parts) < 2 || parts[0] != "$SRV" {
+			return nil
+		}
+		if len(parts) >= 3 && parts[2] != s.Name {
+			return nil // another service's
+		}
+		if len(parts) >= 4 && parts[3] != s.ID {
+			return nil // another instance's
+		}
+		var v any
+		switch parts[1] {
+		case "PING":
+			v = micro.Ping{ServiceIdentity: s.identity(), Type: micro.PingResponseType}
+		case "INFO":
+			v = Info(s, current())
+		case "STATS":
+			st := micro.Stats{ServiceIdentity: s.identity(), Type: micro.StatsResponseType, Started: started,
+				Endpoints: []*micro.EndpointStats{}}
+			for _, e := range current() {
+				st.Endpoints = append(st.Endpoints, &micro.EndpointStats{Name: e.Name(), Subject: e.Subject, QueueGroup: e.Queue})
+			}
+			v = st
+		default:
+			return nil
+		}
+		body, err := json.Marshal(v)
+		if err != nil {
+			return nil
+		}
+		return body
+	}
+	var stops []func()
+	for _, verb := range []string{"PING", "INFO", "STATS"} {
+		// Exactly the questions asked of every service and of this one by name and instance — what the
+		// grants allow (novox/hq ADR 0197). A wildcard is refused by the bus.
+		for _, subject := range []string{"$SRV." + verb, "$SRV." + verb + "." + s.Name, "$SRV." + verb + "." + s.Name + "." + s.ID} {
+			stop, err := conn.Raw(subject, answer)
+			if err != nil {
+				for _, st := range stops {
+					st()
+				}
+				return func() {}, err
+			}
+			stops = append(stops, stop)
+		}
+	}
+	return func() {
+		for _, st := range stops {
+			st()
+		}
+	}, nil
+}
+
+// Gather asks every service on the bus what it serves and answers what came back within the window.
+// An answer that is not an info_response is skipped.
+func Gather(conn *bus.Conn) ([]micro.Info, error) {
+	raw, err := conn.Gather("$SRV.INFO", nil, Window)
+	if err != nil {
+		return nil, err
+	}
+	var out []micro.Info
+	for _, b := range raw {
+		var i micro.Info
+		if json.Unmarshal(b, &i) != nil || i.Type != micro.InfoResponseType {
+			continue
+		}
+		out = append(out, i)
+	}
+	return out, nil
+}
+
+// Endpoints reads an info_response's endpoints back into what they announce.
+func Endpoints(i micro.Info) []Endpoint {
+	var out []Endpoint
+	for _, e := range i.Endpoints {
+		md := e.Metadata
+		out = append(out, Endpoint{
+			Kind: md["kind"], Module: md["module"], Tool: md["tool"], Seat: md["seat"], Scope: md["scope"],
+			Node: md["node"], Description: md["description"], Schema: json.RawMessage(md["schema"]),
+			Interchangeable: md["interchangeable"] == "true", Subject: e.Subject, Queue: e.QueueGroup,
+		})
+	}
+	return out
+}

node-tools/internal/bus/bus.go

@@ -0,0 +1,735 @@
+// Package bus is the node runtime's connection to the mesh bus, on NATS (novox/hq design 25, design
+// 29, ADR 0160, ADR 0175). It is the Go port of node-tools' broker-nats.ts, and speaks the same
+// wire: the same subjects, the same JSON request and reply bodies, the same event headers.
+//
+//	mesh.mod.<module>.event.<type>   an event a module emits
+//	mesh.mod.<module>.tool.<tool>    a tool a module serves
+//	mesh.seat.<seat>.tool.<verb>     a role's verb, answered by whoever holds the seat
+package bus
+
+import (
+	"context"
+	"crypto/sha256"
+	"crypto/tls"
+	"crypto/x509"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"log"
+	"regexp"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/nats-io/nats.go"
+	"github.com/nats-io/nats.go/jetstream"
+
+	"github.com/novox/mesh-tools/node-tools/internal/wire"
+)
+
+// RequestTimeout is how long a call waits for its answer — what modules already expect.
+const RequestTimeout = 30 * time.Second
+
+const assignmentsStream = "ASSIGNMENTS"
+
+// Credential is a broker credential as the mesh delivers it (novox/hq ADR 0120).
+type Credential struct {
+	URL         string  `json:"url"`
+	Fingerprint string  `json:"fingerprint,omitempty"`
+	Node        string  `json:"node,omitempty"`
+	Module      string  `json:"module,omitempty"`
+	User        string  `json:"user,omitempty"`
+	Password    string  `json:"password,omitempty"`
+	Claims      []Claim `json:"claims,omitempty"`
+}
+
+// Claim is a seat a module claims, with the verbs it promises (novox/hq ADR 0159).
+type Claim struct {
+	Seat   string   `json:"seat"`
+	Scope  string   `json:"scope,omitempty"`
+	Serves []string `json:"serves,omitempty"`
+}
+
+// Membership is what the mesh issued one assignment (novox/hq ADR 0160).
+type Membership struct {
+	Node    string              `json:"node"`
+	Module  string              `json:"module"`
+	Serves  []Served            `json:"serves"`
+	Seats   []SeatVerb          `json:"seats,omitempty"`
+	Emits   string              `json:"emits"`
+	Reaches map[string][]string `json:"reaches,omitempty"`
+	Tools   string              `json:"tools"`
+}
+
+// Served is an address a tool is answered on; `{tool}` stands for the tool's name.
+type Served struct {
+	Subject string `json:"subject"`
+	Queue   string `json:"queue,omitempty"`
+}
+
+// SeatVerb is one verb of a seat a module holds, where it is answered.
+type SeatVerb struct {
+	Seat    string `json:"seat"`
+	Verb    string `json:"verb"`
+	Subject string `json:"subject"`
+}
+
+// Envelope is an event as a module emits it: the body is the payload, the metadata rides as headers
+// (novox/hq ADR 0042).
+type Envelope struct {
+	Key     string            `json:"key"`
+	Node    string            `json:"node,omitempty"`
+	Body    json.RawMessage   `json:"body"`
+	Headers map[string]string `json:"headers,omitempty"`
+}
+
+// Answered is a call's result and the machine that gave it (novox/hq ADR 0159).
+type Answered struct {
+	Result json.RawMessage
+	Node   string
+}
+
+// Handler answers one request body.
+type Handler func(body json.RawMessage) (any, error)
+
+// ErrPin is a bus whose certificate is not the one the mesh pinned: final, never retried.
+var ErrPin = errors.New("the bus's certificate does not match the pin")
+
+// Fatal is why a connection failure is final rather than "not yet", or "" when waiting may fix it —
+// the same classification the TypeScript runtime makes.
+func Fatal(err error) string {
+	if err == nil {
+		return ""
+	}
+	msg := err.Error()
+	if errors.Is(err, ErrPin) || strings.Contains(msg, ErrPin.Error()) {
+		return "the bus's certificate does not match the pin"
+	}
+	if regexp.MustCompile(`(?i)invalid url|no servers available for connection: .*url`).MatchString(msg) ||
+		strings.Contains(msg, "nats: invalid url") {
+		return "the bus address is not a usable URL"
+	}
+	if regexp.MustCompile(`(?i)authorization violation|user authentication expired|permissions violation`).MatchString(msg) {
+		return "the bus refused this account"
+	}
+	return ""
+}
+
+func normalizeFingerprint(f string) string {
+	f = strings.TrimSpace(f)
+	if len(f) > 7 && strings.EqualFold(f[:7], "sha256:") {
+		f = f[7:]
+	}
+	return strings.ToLower(strings.ReplaceAll(f, ":", ""))
+}
+
+// pinned accepts exactly the certificate with this SHA-256 and no other. The pin is the only check:
+// the bus's certificate names the seat, not the address a machine dials it by.
+func pinned(want string) *tls.Config {
+	want = normalizeFingerprint(want)
+	return &tls.Config{
+		InsecureSkipVerify: true, //nolint:gosec // replaced by the pin, which is stricter
+		MinVersion:         tls.VersionTLS12,
+		VerifyPeerCertificate: func(raw [][]byte, _ [][]*x509.Certificate) error {
+			if len(raw) == 0 {
+				return fmt.Errorf("%w: it presented none", ErrPin)
+			}
+			sum := sha256.Sum256(raw[0])
+			if got := hex.EncodeToString(sum[:]); got != want {
+				return fmt.Errorf("%w: it presented %s, not the pinned %s", ErrPin, got, want)
+			}
+			return nil
+		},
+	}
+}
+
+// Conn is the runtime's connection: the module it is, the memberships it follows, the subjects it
+// answers.
+type Conn struct {
+	nc     *nats.Conn
+	js     nats.JetStreamContext
+	self   string
+	node   string
+	cred   Credential
+	mu     sync.Mutex
+	issued map[string]*Membership // module → membership; present with nil = followed, none issued
+	onNew  []func(Membership)
+	subs   []*nats.Subscription
+	Logf   func(format string, args ...any)
+}
+
+// Connect dials the bus as the credential's module. A module's subjects come from its credential,
+// never from its calls (ADR 0074).
+func Connect(cred Credential) (*Conn, error) {
+	if cred.Module == "" {
+		return nil, errors.New("a broker credential with no module: the runtime derives its subjects " +
+			"from the account the mesh issued, and cannot guess which module it is")
+	}
+	node := cred.Node
+	if node == "" {
+		node = "?"
+	}
+	opts := []nats.Option{
+		nats.Name(node + "." + cred.Module),
+		// Reconnect forever: the bus restarting is an upgrade, not a reason to exit.
+		nats.MaxReconnects(-1),
+	}
+	if cred.User != "" {
+		opts = append(opts, nats.UserInfo(cred.User, cred.Password),
+			// Its own inbox: every user's inbox is private to it (design 25 §4).
+			nats.CustomInboxPrefix("_INBOX."+cred.User))
+	}
+	if strings.TrimSpace(cred.Fingerprint) != "" {
+		opts = append(opts, nats.Secure(pinned(cred.Fingerprint)))
+	}
+	nc, err := nats.Connect(cred.URL, opts...)
+	if err != nil {
+		return nil, err
+	}
+	js, err := nc.JetStream()
+	if err != nil {
+		nc.Close()
+		return nil, err
+	}
+	c := &Conn{nc: nc, js: js, self: cred.Module, node: cred.Node, cred: cred,
+		issued: map[string]*Membership{}, Logf: log.Printf}
+	c.Follow(cred.Module)
+	return c, nil
+}
+
+// Module is what this connection is.
+func (c *Conn) Module() string { return c.self }
+
+// Node is the machine this connection's account is scoped to.
+func (c *Conn) Node() string { return c.node }
+
+// Credential is what this connection was opened with.
+func (c *Conn) Credential() Credential { return c.cred }
+
+// MembershipSubject is the one address a runtime derives for an assignment (ADR 0160).
+func MembershipSubject(node, module string) string {
+	return "mesh.assignment." + node + "." + module
+}
+
+// Follow reads a module's membership on this machine once and follows it live, so its tools are
+// served where the mesh issued them (ADR 0175).
+func (c *Conn) Follow(module string) {
+	c.mu.Lock()
+	if c.node == "" {
+		c.mu.Unlock()
+		return
+	}
+	if _, has := c.issued[module]; has {
+		c.mu.Unlock()
+		return
+	}
+	c.issued[module] = nil
+	c.mu.Unlock()
+	subject := MembershipSubject(c.node, module)
+	// The subject-addressed direct get: the one address the mesh grants this account on the
+	// stream's API.
+	if got, err := c.nc.Request("$JS.API.DIRECT.GET."+assignmentsStream+"."+subject, nil, 5*time.Second); err == nil {
+		if got.Header.Get("Status") == "" && len(got.Data) > 0 {
+			var m Membership
+			if json.Unmarshal(got.Data, &m) == nil {
+				c.mu.Lock()
+				c.issued[module] = &m
+				c.mu.Unlock()
+			}
+		}
+	}
+	if c.Membership(module) == nil {
+		c.Logf("[mesh-tools] no membership issued for %s on %s yet; serving the derived shape until one arrives", module, c.node)
+	}
+	sub, err := c.nc.Subscribe(subject, func(msg *nats.Msg) {
+		var m Membership
+		if err := json.Unmarshal(msg.Data, &m); err != nil {
+			c.Logf("[mesh-tools] a membership arrived that is not one: %v", err)
+			return
+		}
+		c.mu.Lock()
+		c.issued[module] = &m
+		handlers := append([]func(Membership){}, c.onNew...)
+		c.mu.Unlock()
+		c.Logf("[mesh-tools] %s on %s was issued a new membership; re-serving on it", module, c.node)
+		for _, h := range handlers {
+			h(m)
+		}
+		_ = c.nc.Flush()
+	})
+	if err == nil {
+		c.track(sub)
+	}
+}
+
+// Membership is what the mesh issued a module here, or nil when nothing has been issued.
+func (c *Conn) Membership(module string) *Membership {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.issued[module]
+}
+
+// Following says whether this connection follows a module's membership.
+func (c *Conn) Following(module string) bool {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	_, has := c.issued[module]
+	return has
+}
+
+// Serving is every module whose membership this connection follows.
+func (c *Conn) Serving() []string {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	out := make([]string, 0, len(c.issued))
+	for m := range c.issued {
+		out = append(out, m)
+	}
+	return out
+}
+
+// OnMembership is called with every new membership any followed module is issued.
+func (c *Conn) OnMembership(h func(Membership)) {
+	c.mu.Lock()
+	c.onNew = append(c.onNew, h)
+	c.mu.Unlock()
+}
+
+func (c *Conn) track(s *nats.Subscription) {
+	c.mu.Lock()
+	c.subs = append(c.subs, s)
+	c.mu.Unlock()
+}
+
+// servedOn is where a served module's tool is answered: its membership's subjects when issued, the
+// derived shape otherwise (the shape the mesh issues on day one).
+func (c *Conn) servedOn(module, tool string) []Served {
+	if m := c.Membership(module); m != nil {
+		out := make([]Served, 0, len(m.Serves)+1)
+		for _, s := range m.Serves {
+			out = append(out, Served{Subject: strings.ReplaceAll(s.Subject, "{tool}", tool), Queue: s.Queue})
+		}
+		if tool == "tools" && m.Tools != "" {
+			found := false
+			for _, s := range out {
+				found = found || s.Subject == m.Tools
+			}
+			if !found {
+				out = append([]Served{{Subject: m.Tools, Queue: "serve." + module}}, out...)
+			}
+		}
+		return out
+	}
+	base := "mesh.mod." + module + ".tool." + tool
+	out := []Served{{Subject: base, Queue: "serve." + module}}
+	if c.node != "" {
+		out = append(out, Served{Subject: base + "." + c.node})
+	}
+	return out
+}
+
+type reply struct {
+	Result any    `json:"result,omitempty"`
+	Error  string `json:"error,omitempty"`
+	Node   string `json:"node,omitempty"`
+}
+
+// answerOn answers one subject with one handler, and says which machine answered (ADR 0159).
+func (c *Conn) answerOn(subject, queue string, h Handler) (func(), error) {
+	cb := func(msg *nats.Msg) {
+		go func() {
+			var r reply
+			result, err := h(json.RawMessage(msg.Data))
+			if err != nil {
+				r.Error = err.Error()
+			} else {
+				r.Result = nullable(result)
+			}
+			r.Node = c.node
+			body, _ := wire.Marshal(r)
+			_ = msg.Respond(body)
+		}()
+	}
+	var sub *nats.Subscription
+	var err error
+	if queue != "" {
+		sub, err = c.nc.QueueSubscribe(subject, queue, cb)
+	} else {
+		sub, err = c.nc.Subscribe(subject, cb)
+	}
+	if err != nil {
+		return func() {}, err
+	}
+	c.track(sub)
+	return func() { _ = sub.Unsubscribe() }, nil
+}
+
+// nullable keeps a nil result as JSON null rather than dropping the key: the TypeScript reply always
+// carries `result` when the handler did not throw.
+func nullable(v any) any {
+	if v == nil {
+		return json.RawMessage("null")
+	}
+	return v
+}
+
+// HandleSubject answers a subject outright: a seat's verb where the mesh issued it.
+func (c *Conn) HandleSubject(subject string, h Handler) (func(), error) {
+	return c.answerOn(subject, "", h)
+}
+
+// Handle serves `<module>.<tool>` where the mesh issued that module, and follows its membership:
+// when a new one arrives, it serves where it now says and stops where it no longer does.
+func (c *Conn) Handle(key string, h Handler) (func(), error) {
+	if strings.HasPrefix(key, "seat:") {
+		subject, err := ToolSubject(key, c.self)
+		if err != nil {
+			return func() {}, err
+		}
+		return c.answerOn(subject, "", h)
+	}
+	module, tool := c.self, key
+	if dot := strings.Index(key, "."); dot >= 0 {
+		module, tool = key[:dot], key[dot+1:]
+	}
+	if module != c.self && !c.Following(module) {
+		return func() {}, fmt.Errorf("%s cannot serve %s: a module serves its own tools, and a runtime "+
+			"those of the modules it follows", c.self, key)
+	}
+	var mu sync.Mutex
+	var stops []func()
+	serve := func() {
+		mu.Lock()
+		defer mu.Unlock()
+		for _, s := range stops {
+			s()
+		}
+		stops = nil
+		for _, s := range c.servedOn(module, tool) {
+			if stop, err := c.answerOn(s.Subject, s.Queue, h); err == nil {
+				stops = append(stops, stop)
+			} else {
+				c.Logf("[mesh-tools] cannot serve %s on %s: %v", key, s.Subject, err)
+			}
+		}
+	}
+	serve()
+	c.OnMembership(func(m Membership) {
+		if m.Module == module {
+			serve()
+		}
+	})
+	return func() {
+		mu.Lock()
+		defer mu.Unlock()
+		for _, s := range stops {
+			s()
+		}
+		stops = nil
+	}, nil
+}
+
+// reachedAt is where a call by key goes: a subject this connection's own membership says it
+// reaches — the machine's when named — else the derived shape.
+func (c *Conn) reachedAt(key string) (string, error) {
+	name, wanted, _ := strings.Cut(key, "@")
+	if m := c.Membership(c.self); m != nil {
+		if reach := m.Reaches[name]; len(reach) > 0 {
+			if wanted == "" {
+				return reach[0], nil
+			}
+			for _, s := range reach {
+				if strings.HasSuffix(s, "."+wanted) {
+					return s, nil
+				}
+			}
+		}
+	}
+	return ToolSubject(key, c.self)
+}
+
+// Ask calls a tool by key — or on a subject the mesh listed for it — and learns which machine
+// answered. Core request/reply: a tool call is never persisted (design 25 §3).
+func (c *Conn) Ask(key string, body any, on string) (Answered, error) {
+	subject := on
+	if subject == "" {
+		s, err := c.reachedAt(key)
+		if err != nil {
+			return Answered{}, err
+		}
+		subject = s
+	}
+	data, err := wire.Marshal(body)
+	if err != nil {
+		return Answered{}, err
+	}
+	msg, err := c.nc.Request(subject, data, RequestTimeout)
+	if err != nil {
+		if errors.Is(err, nats.ErrNoResponders) {
+			return Answered{}, errors.New("503 no responders")
+		}
+		if errors.Is(err, nats.ErrTimeout) {
+			return Answered{}, errors.New("timeout")
+		}
+		return Answered{}, err
+	}
+	var r struct {
+		Result json.RawMessage `json:"result"`
+		Error  string          `json:"error"`
+		Node   string          `json:"node"`
+	}
+	if err := json.Unmarshal(msg.Data, &r); err != nil {
+		return Answered{}, err
+	}
+	if r.Error != "" {
+		return Answered{}, errors.New(r.Error)
+	}
+	return Answered{Result: r.Result, Node: r.Node}, nil
+}
+
+// PublishAs emits an event as a module: published into JetStream and awaited, de-duplicated by its
+// own id (ADR 0042). The body is the payload; the metadata rides as headers.
+func (c *Conn) PublishAs(module string, env Envelope) error {
+	msg := nats.NewMsg("mesh.mod." + module + ".event." + env.Key)
+	for k, v := range env.Headers {
+		msg.Header.Set(k, v)
+	}
+	if env.Headers["content-type"] == "" {
+		msg.Header.Set("content-type", "application/json")
+	}
+	if env.Node != "" {
+		msg.Header.Set("x-node", env.Node)
+	}
+	body := env.Body
+	if len(body) == 0 {
+		body = json.RawMessage("null")
+	}
+	msg.Data = body
+	var opts []nats.PubOpt
+	if id := env.Headers["x-event-id"]; id != "" {
+		opts = append(opts, nats.MsgId(id))
+	}
+	_, err := c.js.PublishMsg(msg, opts...)
+	return err
+}
+
+// ServedOn is where a served module's tool is answered right now: the membership's subjects when
+// issued, the derived shape otherwise — what Handle subscribes, for what announces it (ADR 0197).
+func (c *Conn) ServedOn(module, tool string) []Served { return c.servedOn(module, tool) }
+
+// Raw answers one subject with a function of the request, not a tool's reply envelope: the NATS
+// services protocol's discovery subjects answer in their own format (novox/hq ADR 0197). A nil
+// answer is no reply — the request was for another service.
+func (c *Conn) Raw(subject string, answer func(subject string, data []byte) []byte) (func(), error) {
+	sub, err := c.nc.Subscribe(subject, func(msg *nats.Msg) {
+		if body := answer(msg.Subject, msg.Data); body != nil {
+			_ = msg.Respond(body)
+		}
+	})
+	if err != nil {
+		return func() {}, err
+	}
+	c.track(sub)
+	return func() { _ = sub.Unsubscribe() }, nil
+}
+
+// Gather publishes one request and collects every answer that arrives within the window: a
+// discovery request every service instance answers (ADR 0197). It never stops early — how many will
+// answer is what it is finding out.
+func (c *Conn) Gather(subject string, body []byte, window time.Duration) ([][]byte, error) {
+	inbox := c.nc.NewRespInbox()
+	sub, err := c.nc.SubscribeSync(inbox)
+	if err != nil {
+		return nil, err
+	}
+	defer func() { _ = sub.Unsubscribe() }()
+	if err := c.nc.PublishRequest(subject, inbox, body); err != nil {
+		return nil, err
+	}
+	var out [][]byte
+	deadline := time.Now().Add(window)
+	for {
+		left := time.Until(deadline)
+		if left <= 0 {
+			return out, nil
+		}
+		msg, err := sub.NextMsg(left)
+		if err != nil {
+			if errors.Is(err, nats.ErrTimeout) {
+				return out, nil
+			}
+			return out, err
+		}
+		if len(msg.Data) > 0 {
+			out = append(out, msg.Data)
+		}
+	}
+}
+
+// Flush waits until the bus has every subscription made so far, so what is served is answerable
+// when this returns.
+func (c *Conn) Flush() { _ = c.nc.Flush() }
+
+// Close unsubscribes everything and drains, so an in-flight reply is finished rather than dropped.
+func (c *Conn) Close() {
+	c.mu.Lock()
+	subs := c.subs
+	c.subs = nil
+	c.mu.Unlock()
+	for _, s := range subs {
+		_ = s.Unsubscribe()
+	}
+	_ = c.nc.Drain()
+}
+
+// ToolSubject is a tool's subject. A bare name is this module's own; `<module>.<tool>` another's;
+// `seat:<seat>.<verb>` a role's, with `@<node>` for a node-scoped seat (design 33 §4).
+func ToolSubject(key, self string) (string, error) {
+	if strings.HasPrefix(key, "seat:") {
+		rest := strings.TrimPrefix(key, "seat:")
+		dot := strings.Index(rest, ".")
+		if dot < 0 {
+			return "", fmt.Errorf("%q names a seat and no verb: seat:<seat>.<verb>", key)
+		}
+		seat := rest[:dot]
+		verb, node, _ := strings.Cut(rest[dot+1:], "@")
+		if node != "" {
+			return "mesh.seat." + seat + ".tool." + verb + "." + node, nil
+		}
+		return "mesh.seat." + seat + ".tool." + verb, nil
+	}
+	name, node, _ := strings.Cut(key, "@")
+	var base string
+	if dot := strings.Index(name, "."); dot < 0 {
+		base = "mesh.mod." + self + ".tool." + name
+	} else {
+		base = "mesh.mod." + name[:dot] + ".tool." + name[dot+1:]
+	}
+	if node != "" {
+		return base + "." + node, nil
+	}
+	return base, nil
+}
+
+// SeatToolSubject is a seat's verb as its holder serves it: flat for a mesh seat, carrying the
+// machine for a node-scoped one.
+func SeatToolSubject(seat, verb, scope, node string) string {
+	base := "mesh.seat." + seat + ".tool." + verb
+	if scope == "node" && node != "" {
+		return base + "." + node
+	}
+	return base
+}
+
+// AskAs calls a tool on a module's behalf (novox/hq ADR 0198): a bare key is that module's own tool,
+// `<module>.<tool>` another's, `seat:<seat>.<verb>[@<node>]` a role's — resolved through what the
+// mesh issued that module to reach, as its own runtime resolved it, else the derived shape.
+func (c *Conn) AskAs(module, key string, body any) (Answered, error) {
+	name, wanted, _ := strings.Cut(key, "@")
+	subject := ""
+	if m := c.Membership(module); m != nil {
+		if reach := m.Reaches[name]; len(reach) > 0 {
+			subject = reach[0]
+			if wanted != "" {
+				subject = ""
+				for _, s := range reach {
+					if strings.HasSuffix(s, "."+wanted) {
+						subject = s
+					}
+				}
+			}
+		}
+	}
+	if subject == "" {
+		s, err := ToolSubject(key, module)
+		if err != nil {
+			return Answered{}, err
+		}
+		subject = s
+	}
+	return c.Ask(key, body, subject)
+}
+
+// EventsStream is where every module's events land, and ConsumerOf the durable consumer the
+// controller makes for a module on a machine: the same names the module's own runtime bound
+// (node-tools/src/broker-nats.ts), so moving the module into the node's runtime neither loses an
+// event nor sees one twice.
+const EventsStream = "EVENTS"
+
+// ConsumerOf is a module's durable consumer on a machine: `<node>_<module>`.
+func ConsumerOf(node, module string) string {
+	if node == "" {
+		node = "?"
+	}
+	return node + "_" + module
+}
+
+// NakDelay is how long an event a handler failed waits before it is offered again: a transient cause
+// gets another attempt, a permanent one exhausts the consumer's max-deliver rather than spinning.
+var NakDelay = 5 * time.Second
+
+// ConsumeAs reads a module's durable consumer and hands each event to deliver (novox/hq ADR 0198):
+// acknowledged when deliver returns nil, negatively acknowledged after NakDelay when it returns an
+// error, terminated when it is not an event at all. The consumer is the controller's to create; this
+// binds to it and never makes one. Runs until stopped.
+func (c *Conn) ConsumeAs(module string, deliver func(Envelope) error) (func(), error) {
+	durable := ConsumerOf(c.node, module)
+	js, err := jetstream.New(c.nc)
+	if err != nil {
+		return nil, err
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	// Bound by name, never created and never matched against a subject: the consumer and its
+	// filters are the controller's (design 29 §3), exactly as the module's own runtime bound it.
+	consumer, err := js.Consumer(ctx, EventsStream, durable)
+	if err != nil {
+		return nil, fmt.Errorf("binding %s's consumer %s: %w", module, durable, err)
+	}
+	reading, err := consumer.Consume(func(msg jetstream.Msg) {
+		env, ok := envelopeOf(msg.Subject(), msg.Headers(), msg.Data())
+		if !ok {
+			// Unparseable: redelivering bytes no version of a handler can read is a loop.
+			_ = msg.Term()
+			return
+		}
+		if err := deliver(env); err != nil {
+			_ = msg.NakWithDelay(NakDelay)
+			return
+		}
+		_ = msg.Ack()
+	})
+	if err != nil {
+		return nil, fmt.Errorf("reading %s's consumer %s: %w", module, durable, err)
+	}
+	var once sync.Once
+	return func() { once.Do(reading.Stop) }, nil
+}
+
+// envelopeOf rebuilds the envelope a module sees from a delivered event: its key is the emitter and
+// the event, recovered from the subject; its metadata rides as headers (novox/hq ADR 0042).
+func envelopeOf(subject string, header nats.Header, data []byte) (Envelope, bool) {
+	if !json.Valid(data) {
+		return Envelope{}, false
+	}
+	headers := map[string]string{}
+	for k := range header {
+		headers[k] = header.Get(k)
+	}
+	return Envelope{Key: keyOf(subject), Node: headers["x-node"], Body: json.RawMessage(data), Headers: headers}, true
+}
+
+// keyOf is the key a module sees for an event subject: `mesh.mod.<emitter>.event.<event>` is
+// `<emitter>.<event>` — the vocabulary its manifest names what it consumes in.
+func keyOf(subject string) string {
+	before, event, found := strings.Cut(subject, ".event.")
+	if !found {
+		return subject
+	}
+	parts := strings.Split(before, ".")
+	if emitter := parts[len(parts)-1]; emitter != "" {
+		return emitter + "." + event
+	}
+	return event
+}

node-tools/internal/bus/bus_test.go

@@ -0,0 +1,48 @@
+package bus
+
+import (
+	"errors"
+	"fmt"
+	"testing"
+)
+
+func TestSubjectsAreTheOnesTheTypeScriptRuntimeUses(t *testing.T) {
+	for key, want := range map[string]string{
+		"status":                      "mesh.mod.self.tool.status",
+		"alpha.one":                   "mesh.mod.alpha.tool.one",
+		"alpha.one@anchor":            "mesh.mod.alpha.tool.one.anchor",
+		"seat:node-shelf.list":        "mesh.seat.node-shelf.tool.list",
+		"seat:node-shelf.list@anchor": "mesh.seat.node-shelf.tool.list.anchor",
+	} {
+		if got, err := ToolSubject(key, "self"); err != nil || got != want {
+			t.Errorf("%s: %s %v, want %s", key, got, err, want)
+		}
+	}
+	if _, err := ToolSubject("seat:nothing", "self"); err == nil {
+		t.Error("a seat with no verb was accepted")
+	}
+	if SeatToolSubject("s", "v", "node", "n") != "mesh.seat.s.tool.v.n" || SeatToolSubject("s", "v", "mesh", "n") != "mesh.seat.s.tool.v" {
+		t.Error("seat subjects")
+	}
+}
+
+func TestAFingerprintIsReadHoweverItIsWritten(t *testing.T) {
+	for _, f := range []string{"sha256:AB:CD:ef", "abcdef", "ABCDEF", "SHA256:abcdef"} {
+		if got := normalizeFingerprint(f); got != "abcdef" {
+			t.Errorf("%s → %s", f, got)
+		}
+	}
+}
+
+func TestWhatWaitingCannotFixIsFinal(t *testing.T) {
+	for err, want := range map[error]string{
+		fmt.Errorf("x509: %w: it presented aa", ErrPin):                   "the bus's certificate does not match the pin",
+		errors.New("nats: Authorization Violation"):                       "the bus refused this account",
+		errors.New("nats: invalid url"):                                   "the bus address is not a usable URL",
+		errors.New("dial tcp 10.0.0.1:4222: connect: connection refused"): "",
+	} {
+		if got := Fatal(err); got != want {
+			t.Errorf("%v → %q, want %q", err, got, want)
+		}
+	}
+}

node-tools/internal/console/address.go

@@ -0,0 +1,730 @@
+package console
+
+// The mesh's tools found by address, not announced whole (novox/hq ADR 0195, to-be 34 §3a).
+//
+// The console announces five tools. Everything the mesh answers is reached through them by one
+// address per layer:
+//
+//	<seat>.<verb>              a seat held once for the mesh — its holder answers
+//	<node>/<seat>.<verb>       a seat held once per machine — that machine's holder answers
+//	<node>/<module>.<tool>     a module assigned to a machine — that assignment answers
+//	<module>.<tool>            also, for a module whose instances are interchangeable (ADR 0160)
+//
+// A module that is not interchangeable is called with its machine or refused, naming the machines
+// it runs on: "whichever answers" is no answer for state a machine holds.
+//
+// Every discovery verb asks the mesh when it is called — kept a few seconds at most, never for a
+// session — so a tool that arrived a minute ago is found without the client reconnecting.
+
+import (
+	"encoding/json"
+	"fmt"
+	"sort"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/novox/mesh-tools/node-tools/internal/announce"
+	"github.com/novox/mesh-tools/node-tools/internal/bus"
+)
+
+// IndexKept is how long what the mesh answered is kept before it is asked again: long enough that
+// one agent turn's search, describe and call ask once, short enough that nothing goes stale.
+var IndexKept = 5 * time.Second
+
+// The five tools the console announces. Names of the API's kind — letters, digits, `_`, `-`.
+const (
+	verbOverview = "mesh_overview"
+	verbMachine  = "mesh_machine"
+	verbSearch   = "mesh_search"
+	verbDescribe = "mesh_describe"
+	verbCall     = "mesh_call"
+)
+
+// searchCap is how many matches a search answers before it says how many more there were.
+const searchCap = 25
+
+const grammar = "Addresses: `<seat>.<verb>` for a seat held once for the mesh (e.g. `mesh-controller.nodes`); " +
+	"`<node>/<seat>.<verb>` for a seat every machine holds (e.g. `ace/node-packet-filter.rules`); " +
+	"`<node>/<module>.<tool>` for a module on one machine (e.g. `novox/postgres.postgres_list_databases`); " +
+	"and `<module>.<tool>` also for a module whose instances are interchangeable."
+
+// discovery is the five tools as tools/list announces them.
+func discovery() []map[string]any {
+	str := func(desc string) map[string]any { return map[string]any{"type": "string", "description": desc} }
+	obj := func(props map[string]any, required ...string) map[string]any {
+		s := map[string]any{"type": "object", "properties": props}
+		if len(required) > 0 {
+			s["required"] = required
+		}
+		return s
+	}
+	return []map[string]any{
+		{"name": verbOverview, "inputSchema": obj(map[string]any{}),
+			"description": "The mesh at a glance: the seats it holds once for the whole mesh with their verbs, the seats " +
+				"every machine holds, and its machines. Start here, then `mesh_machine` for one machine. " + grammar},
+		{"name": verbMachine, "inputSchema": obj(map[string]any{"node": str("the machine, as mesh_overview names it")}, "node"),
+			"description": "One machine: the seats it holds with their verbs, and the modules assigned to it with their tools — " +
+				"each with the address to describe or call it by. " + grammar},
+		{"name": verbSearch, "inputSchema": obj(map[string]any{"query": str("words to find in tool names and descriptions, e.g. `postgres databases`")}, "query"),
+			"description": "Find tools anywhere in the mesh by words: every match's address and a line of what it does, across the " +
+				"mesh's seats, the machines' seats and every module on every machine. " + grammar},
+		{"name": verbDescribe, "inputSchema": obj(map[string]any{"address": str("the tool's address")}, "address"),
+			"description": "What one tool does and the arguments it takes, as a JSON schema. The machine is in the address, " +
+				"never an argument. " + grammar},
+		{"name": verbCall, "inputSchema": obj(map[string]any{
+			"address":   str("the tool's address"),
+			"arguments": map[string]any{"type": "object", "description": "the tool's arguments, as mesh_describe gives its schema"},
+		}, "address"),
+			"description": "Call one tool by its address with its arguments; the answer says which machine gave it. " + grammar},
+	}
+}
+
+func isDiscovery(name string) bool {
+	switch name {
+	case verbOverview, verbMachine, verbSearch, verbDescribe, verbCall:
+		return true
+	}
+	return false
+}
+
+// seatInfo is a seat as the mesh's records define it, and who holds it where.
+type seatInfo struct {
+	Seat    string
+	Scope   string // "mesh" or "node"
+	Verbs   []Tool
+	Holders []holder
+}
+
+type holder struct {
+	Module string `json:"module"`
+	Node   string `json:"node"`
+}
+
+// moduleInfo is a module that answers tools: where it runs, whether any instance will do, and its
+// tools as one of its instances described them.
+type moduleInfo struct {
+	Module          string
+	On              []string
+	Interchangeable bool
+	Tools           []Tool
+}
+
+// index is what the mesh answered about itself, at one moment.
+type index struct {
+	Seats        []seatInfo
+	Machines     []string
+	Modules      map[string]*moduleInfo
+	NotAnswering []string
+	Listing      *Listing // the flat catalogue the call path resolves subjects with
+}
+
+func (x *index) seat(name string) *seatInfo {
+	for i := range x.Seats {
+		if x.Seats[i].Seat == name {
+			return &x.Seats[i]
+		}
+	}
+	return nil
+}
+
+func findTool(tools []Tool, name string) *Tool {
+	for i := range tools {
+		if tools[i].Name == name {
+			return &tools[i]
+		}
+	}
+	return nil
+}
+
+// controllerOutput is a controller seat verb's answer: the command's printed output.
+func controllerOutput(conn *bus.Conn, verb string) (string, error) {
+	got, err := conn.Ask("seat:mesh-controller."+verb, map[string]any{}, "")
+	if err != nil {
+		return "", err
+	}
+	var r struct {
+		Output string `json:"output"`
+		OK     *bool  `json:"ok"`
+	}
+	if json.Unmarshal(got.Result, &r) != nil {
+		return "", fmt.Errorf("mesh-controller.%s answered something that is not its output", verb)
+	}
+	if r.OK != nil && !*r.OK {
+		return "", fmt.Errorf("mesh-controller.%s: %s", verb, strings.TrimSpace(r.Output))
+	}
+	return r.Output, nil
+}
+
+// jsonIn is the JSON document a command printed, after any lines it said first: a seat verb runs
+// the controller's command, and a command may warn before it answers.
+func jsonIn(output string) string {
+	t := strings.TrimSpace(output)
+	if strings.HasPrefix(t, "{") || strings.HasPrefix(t, "[") {
+		return t
+	}
+	for _, open := range []string{"\n{", "\n["} {
+		if i := strings.Index(output, open); i >= 0 {
+			return strings.TrimSpace(output[i+1:])
+		}
+	}
+	return ""
+}
+
+// recordedModule is a module as the controller's records hold it (`module list --json`): where the
+// mesh assigned it, and whether it declares tools — what should announce itself, and where.
+type recordedModule struct {
+	Module string   `json:"module"`
+	On     []string `json:"on"`
+	Tools  bool     `json:"tools"`
+}
+
+// recordedMachine is a machine as the controller's records hold it (`node list --json`).
+type recordedMachine struct {
+	Name string `json:"name"`
+}
+
+// indexOn asks the mesh what it holds (novox/hq ADR 0197): what answers, from every runtime's own
+// announcement on the bus — one `$SRV.INFO` request — and what should, from the controller's records
+// read as JSON. Nothing is inferred from a roster and nothing is parsed from print.
+func indexOn(conn *bus.Conn) (*index, error) {
+	var wg sync.WaitGroup
+	var nodesOut, modulesOut string
+	wg.Add(2)
+	go func() { defer wg.Done(); nodesOut, _ = controllerOutput(conn, "nodes") }()
+	go func() { defer wg.Done(); modulesOut, _ = controllerOutput(conn, "modules") }()
+	infos, err := announce.Gather(conn)
+	wg.Wait()
+	if err != nil {
+		return nil, err
+	}
+
+	l := &Listing{Tools: []Tool{}, NotAnswering: []string{}}
+	x := &index{Modules: map[string]*moduleInfo{}, Listing: l}
+	announced := map[string]map[string]bool{} // module → node → announced something
+	seats := map[string]*seatInfo{}
+	toolAt := map[string]int{} // <module>.<tool> or <seat>.<verb> → index in l.Tools
+	machines := map[string]bool{}
+	for _, info := range infos {
+		for _, e := range announce.Endpoints(info) {
+			if e.Node != "" {
+				machines[e.Node] = true
+			}
+			if announced[e.Module] == nil {
+				announced[e.Module] = map[string]bool{}
+			}
+			announced[e.Module][e.Node] = true
+			switch e.Kind {
+			case announce.KindSeat:
+				st := seats[e.Seat]
+				if st == nil {
+					st = &seatInfo{Seat: e.Seat, Scope: e.Scope}
+					seats[e.Seat] = st
+				}
+				if st.Scope != "node" && e.Scope == "node" {
+					st.Scope = "node"
+				}
+				h := holder{Module: e.Module, Node: e.Node}
+				if !containsHolder(st.Holders, h) {
+					st.Holders = append(st.Holders, h)
+				}
+				key := e.Seat + "." + e.Tool
+				if _, have := toolAt[key]; !have {
+					toolAt[key] = len(l.Tools)
+					t := Tool{Module: e.Seat, Name: e.Tool, Description: e.Description, Input: e.Schema, Seat: true, Scope: st.Scope}
+					l.Tools = append(l.Tools, t)
+					st.Verbs = append(st.Verbs, t)
+				}
+			case announce.KindTool:
+				m := x.Modules[e.Module]
+				if m == nil {
+					m = &moduleInfo{Module: e.Module}
+					x.Modules[e.Module] = m
+				}
+				if e.Node != "" && !contains(m.On, e.Node) {
+					m.On = append(m.On, e.Node)
+				}
+				m.Interchangeable = m.Interchangeable || e.Interchangeable
+				key := e.Module + "." + e.Tool
+				i, have := toolAt[key]
+				if !have {
+					i = len(l.Tools)
+					toolAt[key] = i
+					l.Tools = append(l.Tools, Tool{Module: e.Module, Name: e.Tool, Description: e.Description, Input: e.Schema})
+				}
+				if !contains(l.Tools[i].Subjects, e.Subject) {
+					l.Tools[i].Subjects = append(l.Tools[i].Subjects, e.Subject)
+				}
+			}
+		}
+	}
+	// A tool's subjects as a call looks them up: the plain one any instance answers first, then each
+	// machine's.
+	for i := range l.Tools {
+		t := &l.Tools[i]
+		if t.Seat {
+			continue
+		}
+		plain := "mesh.mod." + t.Module + ".tool." + t.Name
+		sort.SliceStable(t.Subjects, func(a, b int) bool {
+			if (t.Subjects[a] == plain) != (t.Subjects[b] == plain) {
+				return t.Subjects[a] == plain
+			}
+			return t.Subjects[a] < t.Subjects[b]
+		})
+	}
+	for _, t := range l.Tools {
+		if !t.Seat {
+			x.Modules[t.Module].Tools = append(x.Modules[t.Module].Tools, t)
+		}
+	}
+	for _, m := range x.Modules {
+		sort.Strings(m.On)
+	}
+	for _, st := range seats {
+		sort.Slice(st.Holders, func(a, b int) bool { return st.Holders[a].Node < st.Holders[b].Node })
+		x.Seats = append(x.Seats, *st)
+	}
+	sort.Slice(x.Seats, func(i, j int) bool { return x.Seats[i].Seat < x.Seats[j].Seat })
+	sort.SliceStable(l.Tools, func(i, j int) bool {
+		return l.Tools[i].Module+"."+l.Tools[i].Name < l.Tools[j].Module+"."+l.Tools[j].Name
+	})
+
+	// What should have answered: every assignment of a module that declares tools. Silence is named;
+	// a module with no tools is never a name here.
+	var recorded []recordedModule
+	if json.Unmarshal([]byte(jsonIn(modulesOut)), &recorded) == nil {
+		for _, m := range recorded {
+			if !m.Tools {
+				continue
+			}
+			for _, n := range m.On {
+				// A holder of a seat held once for the mesh announces no machine — the seat is the mesh's,
+				// not a machine's — so what it announced without one answers for wherever it is assigned.
+				if !announced[m.Module][n] && !announced[m.Module][""] {
+					l.NotAnswering = append(l.NotAnswering, m.Module+" on "+n)
+				}
+			}
+		}
+	} else {
+		l.NotAnswering = append(l.NotAnswering, "mesh-controller (its records of the modules did not answer, so what is missing cannot be said)")
+	}
+	sort.Strings(l.NotAnswering)
+	x.NotAnswering = l.NotAnswering
+
+	var known []recordedMachine
+	if json.Unmarshal([]byte(jsonIn(nodesOut)), &known) == nil {
+		for _, n := range known {
+			if n.Name != "" {
+				machines[n.Name] = true
+			}
+		}
+	}
+	for n := range machines {
+		x.Machines = append(x.Machines, n)
+	}
+	sort.Strings(x.Machines)
+	return x, nil
+}
+
+func containsHolder(hs []holder, h holder) bool {
+	for _, x := range hs {
+		if x == h {
+			return true
+		}
+	}
+	return false
+}
+
+func (s *Surface) index() (*index, error) {
+	s.mu.Lock()
+	if s.idx != nil && time.Since(s.idxAt) <= IndexKept {
+		x := s.idx
+		s.mu.Unlock()
+		return x, nil
+	}
+	s.mu.Unlock()
+	x, err := indexOn(s.conn)
+	if err != nil {
+		return nil, err
+	}
+	s.mu.Lock()
+	s.idx, s.idxAt = x, time.Now()
+	s.mu.Unlock()
+	return x, nil
+}
+
+// target is what an address resolves to.
+type target struct {
+	Address string
+	Key     string // the call key the existing path takes: seat:<s>.<v>[@node] or <m>.<t>[@node]
+	Name    string // <seat>.<verb> or <module>.<tool>, for the listing's subject lookup
+	Node    string
+	Tool    Tool
+	Seat    bool
+}
+
+// resolve turns an address into exactly one target, or says why it cannot.
+func resolve(x *index, address string) (target, error) {
+	address = strings.TrimSpace(address)
+	node, rest, hasNode := strings.Cut(address, "/")
+	if !hasNode {
+		rest, node = address, ""
+	}
+	dot := strings.Index(rest, ".")
+	if dot <= 0 || dot == len(rest)-1 || strings.Contains(rest, "/") {
+		return target{}, fmt.Errorf("%q is not an address. %s", address, grammar)
+	}
+	prefix, name := rest[:dot], rest[dot+1:]
+
+	if s := x.seat(prefix); s != nil {
+		verb := findTool(s.Verbs, name)
+		if verb == nil {
+			return target{}, fmt.Errorf("the seat %s has no verb %s; it has %s", prefix, name, toolNames(s.Verbs))
+		}
+		if s.Scope == "node" {
+			if node == "" {
+				return target{}, fmt.Errorf("%s is held once per machine: write <node>/%s — it is held on %s",
+					prefix, rest, orNobody(nodesOf(s.Holders)))
+			}
+			return target{Address: node + "/" + rest, Key: "seat:" + rest + "@" + node, Name: rest, Node: node, Tool: *verb, Seat: true}, nil
+		}
+		if node != "" {
+			return target{}, fmt.Errorf("%s is held once for the whole mesh: write %s, without a machine", prefix, rest)
+		}
+		return target{Address: rest, Key: "seat:" + rest, Name: rest, Tool: *verb, Seat: true}, nil
+	}
+
+	m := x.Modules[prefix]
+	if m == nil {
+		return target{}, fmt.Errorf("nothing in the mesh is called %s: no seat, and no module that answers tools. "+
+			"mesh_search finds a tool by words", prefix)
+	}
+	tool := findTool(m.Tools, name)
+	if tool == nil {
+		return target{}, fmt.Errorf("%s has no tool %s; it has %s", prefix, name, toolNames(m.Tools))
+	}
+	if node == "" {
+		if !m.Interchangeable {
+			return target{}, fmt.Errorf("%s keeps state on each machine it runs on, so a call names the machine: "+
+				"write <node>/%s — it runs on %s", prefix, rest, orNobody(m.On))
+		}
+		return target{Address: rest, Key: rest, Name: rest, Tool: *tool}, nil
+	}
+	if len(m.On) > 0 && !contains(m.On, node) {
+		return target{}, fmt.Errorf("%s does not run on %s; it runs on %s", prefix, node, orNobody(m.On))
+	}
+	return target{Address: node + "/" + rest, Key: rest + "@" + node, Name: rest, Node: node, Tool: *tool}, nil
+}
+
+func contains(xs []string, s string) bool {
+	for _, x := range xs {
+		if x == s {
+			return true
+		}
+	}
+	return false
+}
+
+func toolNames(ts []Tool) string {
+	names := make([]string, 0, len(ts))
+	for _, t := range ts {
+		names = append(names, t.Name)
+	}
+	sort.Strings(names)
+	return strings.Join(names, ", ")
+}
+
+func nodesOf(hs []holder) []string {
+	var out []string
+	for _, h := range hs {
+		if h.Node != "" && !contains(out, h.Node) {
+			out = append(out, h.Node)
+		}
+	}
+	sort.Strings(out)
+	return out
+}
+
+func orNobody(nodes []string) string {
+	if len(nodes) == 0 {
+		return "no machine the mesh knows of"
+	}
+	return strings.Join(nodes, ", ")
+}
+
+// firstLine is a description's first line, for a list.
+func firstLine(s string) string {
+	s = strings.TrimSpace(s)
+	if i := strings.IndexAny(s, "\n"); i >= 0 {
+		s = s[:i]
+	}
+	if len(s) > 160 {
+		s = s[:157] + "…"
+	}
+	return s
+}
+
+// schemaWithoutNode is a tool's schema as an agent passes it: the machine is in the address.
+func schemaWithoutNode(raw json.RawMessage) map[string]any {
+	schema := asSchema(raw)
+	out := map[string]any{}
+	for k, v := range schema {
+		out[k] = v
+	}
+	if p, ok := schema["properties"].(map[string]any); ok {
+		props := map[string]any{}
+		for k, v := range p {
+			if k != "node" {
+				props[k] = v
+			}
+		}
+		out["properties"] = props
+	}
+	if r, ok := schema["required"].([]any); ok {
+		var keep []any
+		for _, k := range r {
+			if k != "node" {
+				keep = append(keep, k)
+			}
+		}
+		if len(keep) == 0 {
+			delete(out, "required")
+		} else {
+			out["required"] = keep
+		}
+	}
+	return out
+}
+
+// answerText is a discovery verb's answer as MCP content: JSON, indented.
+func answerText(v any) map[string]any {
+	var b strings.Builder
+	enc := json.NewEncoder(&b)
+	enc.SetEscapeHTML(false) // `<node>/…` is read by an agent, not embedded in a page
+	enc.SetIndent("", "  ")
+	_ = enc.Encode(v)
+	return map[string]any{"content": []map[string]any{{"type": "text", "text": strings.TrimRight(b.String(), "\n")}}}
+}
+
+func failure(text string) map[string]any {
+	return map[string]any{"content": []map[string]any{{"type": "text", "text": text}}, "isError": true}
+}
+
+// discover answers one of the five.
+func (s *Surface) discover(name string, args map[string]any) map[string]any {
+	x, err := s.index()
+	if err != nil {
+		return failure("the mesh's discovery failed: " + err.Error())
+	}
+	str := func(k string) string { v, _ := args[k].(string); return strings.TrimSpace(v) }
+
+	switch name {
+	case verbOverview:
+		type verbLine struct {
+			Address     string `json:"address"`
+			Description string `json:"description"`
+		}
+		var mesh, node []map[string]any
+		for _, st := range x.Seats {
+			var verbs []verbLine
+			for _, v := range st.Verbs {
+				addr := st.Seat + "." + v.Name
+				if st.Scope == "node" {
+					addr = "<node>/" + addr
+				}
+				verbs = append(verbs, verbLine{addr, firstLine(v.Description)})
+			}
+			entry := map[string]any{"seat": st.Seat, "verbs": verbs}
+			if st.Scope == "node" {
+				entry["held on"] = nodesOf(st.Holders)
+				node = append(node, entry)
+			} else {
+				if h := nodesOf(st.Holders); len(h) > 0 {
+					entry["held on"] = h
+				}
+				mesh = append(mesh, entry)
+			}
+		}
+		modules := 0
+		tools := 0
+		for _, m := range x.Modules {
+			modules++
+			tools += len(m.Tools)
+		}
+		return answerText(map[string]any{
+			"seats of the mesh":   mesh,
+			"seats every machine": node,
+			"machines":            x.Machines,
+			"modules with tools":  fmt.Sprintf("%d modules, %d tools — mesh_machine lists a machine's, mesh_search finds one", modules, tools),
+			"not answering":       x.NotAnswering,
+		})
+
+	case verbMachine:
+		node := str("node")
+		if node == "" {
+			return failure("mesh_machine needs `node`: one of " + orNobody(x.Machines))
+		}
+		if !contains(x.Machines, node) {
+			return failure(fmt.Sprintf("the mesh knows no machine %q; it has %s", node, orNobody(x.Machines)))
+		}
+		var seats []map[string]any
+		for _, st := range x.Seats {
+			if st.Scope != "node" || !contains(nodesOf(st.Holders), node) {
+				continue
+			}
+			var verbs []string
+			for _, v := range st.Verbs {
+				verbs = append(verbs, node+"/"+st.Seat+"."+v.Name)
+			}
+			var by string
+			for _, h := range st.Holders {
+				if h.Node == node {
+					by = h.Module
+				}
+			}
+			seats = append(seats, map[string]any{"seat": st.Seat, "held by": by, "verbs": verbs})
+		}
+		var modules []map[string]any
+		names := make([]string, 0, len(x.Modules))
+		for n := range x.Modules {
+			names = append(names, n)
+		}
+		sort.Strings(names)
+		for _, n := range names {
+			m := x.Modules[n]
+			if !contains(m.On, node) {
+				continue
+			}
+			var tools []map[string]string
+			for _, t := range m.Tools {
+				tools = append(tools, map[string]string{"address": node + "/" + m.Module + "." + t.Name, "does": firstLine(t.Description)})
+			}
+			entry := map[string]any{"module": m.Module, "tools": tools}
+			if m.Interchangeable {
+				entry["interchangeable"] = "any instance answers <module>.<tool> as well"
+			}
+			modules = append(modules, entry)
+		}
+		return answerText(map[string]any{"machine": node, "seats": seats, "modules": modules})
+
+	case verbSearch:
+		query := strings.ToLower(str("query"))
+		if query == "" {
+			return failure("mesh_search needs `query`: words to find, e.g. `postgres databases`")
+		}
+		words := strings.Fields(query)
+		type hit struct {
+			Address string `json:"address"`
+			Does    string `json:"does"`
+			Also    string `json:"also,omitempty"`
+		}
+		var hits []hit
+		matches := func(parts ...string) bool {
+			hay := strings.ToLower(strings.Join(parts, " "))
+			for _, w := range words {
+				if !strings.Contains(hay, w) {
+					return false
+				}
+			}
+			return true
+		}
+		for _, st := range x.Seats {
+			for _, v := range st.Verbs {
+				if !matches(st.Seat, v.Name, v.Description) {
+					continue
+				}
+				if st.Scope == "node" {
+					on := nodesOf(st.Holders)
+					first := "<node>"
+					also := ""
+					if len(on) > 0 {
+						first = on[0]
+						if len(on) > 1 {
+							also = "also on " + strings.Join(on[1:], ", ")
+						}
+					}
+					hits = append(hits, hit{first + "/" + st.Seat + "." + v.Name, firstLine(v.Description), also})
+				} else {
+					hits = append(hits, hit{st.Seat + "." + v.Name, firstLine(v.Description), ""})
+				}
+			}
+		}
+		names := make([]string, 0, len(x.Modules))
+		for n := range x.Modules {
+			names = append(names, n)
+		}
+		sort.Strings(names)
+		for _, n := range names {
+			m := x.Modules[n]
+			for _, t := range m.Tools {
+				if !matches(m.Module, t.Name, t.Description) {
+					continue
+				}
+				switch {
+				case m.Interchangeable:
+					hits = append(hits, hit{m.Module + "." + t.Name, firstLine(t.Description), "any instance; on " + orNobody(m.On)})
+				case len(m.On) == 0:
+					hits = append(hits, hit{"<node>/" + m.Module + "." + t.Name, firstLine(t.Description), "the mesh places it on no machine"})
+				default:
+					also := ""
+					if len(m.On) > 1 {
+						also = "also on " + strings.Join(m.On[1:], ", ")
+					}
+					hits = append(hits, hit{m.On[0] + "/" + m.Module + "." + t.Name, firstLine(t.Description), also})
+				}
+			}
+		}
+		out := map[string]any{"matches": hits}
+		if len(hits) > searchCap {
+			out["matches"] = hits[:searchCap]
+			out["more"] = fmt.Sprintf("%d more; narrow the words", len(hits)-searchCap)
+		}
+		if len(hits) == 0 {
+			out["matches"] = []hit{}
+			out["hint"] = "nothing matched every word; try fewer words, or mesh_overview and mesh_machine to browse"
+		}
+		return answerText(out)
+
+	case verbDescribe:
+		t, err := resolve(x, str("address"))
+		if err != nil {
+			return failure(err.Error())
+		}
+		description := t.Tool.Description
+		if description == "" {
+			description = t.Name
+		}
+		return answerText(map[string]any{"address": t.Address, "description": description,
+			"arguments": schemaWithoutNode(t.Tool.Input)})
+
+	case verbCall:
+		t, err := resolve(x, str("address"))
+		if err != nil {
+			return failure(err.Error())
+		}
+		callArgs := map[string]any{}
+		if a, ok := args["arguments"].(map[string]any); ok {
+			for k, v := range a {
+				if k != "node" {
+					callArgs[k] = v
+				}
+			}
+		}
+		var got bus.Answered
+		if t.Seat {
+			got, err = s.conn.Ask(t.Key, callArgs, "")
+		} else {
+			got, err = callTool(s.conn, t.Key, callArgs, nil, x.Listing)
+		}
+		if err != nil {
+			return failure(whyItFailed(t.Address, err))
+		}
+		content := []map[string]any{{"type": "text", "text": pretty(got.Result)}}
+		if got.Node != "" {
+			content = append(content, map[string]any{"type": "text", "text": "answered by " + got.Node})
+		}
+		return map[string]any{"content": content}
+	}
+	return failure("no discovery verb " + name)
+}

node-tools/internal/console/address_test.go

@@ -0,0 +1,232 @@
+package console
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/novox/mesh-tools/node-tools/internal/announce"
+	mt "github.com/novox/mesh-tools/node-tools/internal/meshtest"
+	"github.com/novox/mesh-tools/node-tools/internal/runtime"
+)
+
+// text is a tool result's first text, and whether it was an error.
+func text(t *testing.T, reply map[string]any) (string, bool) {
+	t.Helper()
+	result, ok := reply["result"].(map[string]any)
+	if !ok {
+		t.Fatalf("no result: %v", reply)
+	}
+	content := result["content"].([]any)
+	isErr, _ := result["isError"].(bool)
+	var parts []string
+	for _, c := range content {
+		parts = append(parts, c.(map[string]any)["text"].(string))
+	}
+	return strings.Join(parts, "\n"), isErr
+}
+
+func call(t *testing.T, endpoint, tool string, args map[string]any) (string, bool) {
+	t.Helper()
+	body, _ := json.Marshal(map[string]any{"jsonrpc": "2.0", "id": 9, "method": "tools/call",
+		"params": map[string]any{"name": tool, "arguments": args}})
+	return text(t, post(t, endpoint, string(body)))
+}
+
+// novox/hq ADR 0195: the console announces five tools, and everything the mesh answers is reached
+// through them by one address per layer.
+func TestTheMeshsToolsAreFoundByAddress(t *testing.T) {
+	was := IndexKept
+	IndexKept = 0 // every discovery asks the mesh, so a module arriving mid-test is found
+	t.Cleanup(func() { IndexKept = was })
+
+	mesh := mt.New(t)
+	// alpha: interchangeable (the mesh issued it a plain subject); beta: state on its machine, holds
+	// the node-shelf seat there.
+	mesh.Issue(t, mt.MembershipOf("alpha", "desk", true, nil))
+	mesh.Issue(t, mt.MembershipOf("beta", "desk", false, map[string][]string{"node-shelf": {"list", "clear"}}))
+	nodeTools := connect(t, "node-tools", "desk")
+	stop, err := runtime.Run(nodeTools, []runtime.Served{
+		{Module: "alpha", Entrypoints: []string{mt.Fixture("many-alpha.serve.mjs")}},
+		{Module: "beta", Entrypoints: []string{mt.Fixture("many-beta.serve.mjs")}},
+	}, nil, (&mt.Logs{}).Logf)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer stop()
+
+	// Nothing may be asked for a roster or a module's `tools` any more (ADR 0197): counted.
+	var asked atomic.Int32
+	watcher := connect(t, "watcher", "")
+	for _, subject := range []string{"mesh.mod.*.tool.tools", "mesh.mod.*.tool.tools.*", "mesh.mod.mesh-catalog.>"} {
+		stop, err := watcher.Raw(subject, func(string, []byte) []byte { asked.Add(1); return nil })
+		if err != nil {
+			t.Fatal(err)
+		}
+		t.Cleanup(stop)
+	}
+
+	// The controller: its records as JSON, as its seat verbs answer them, and its own seat's verbs
+	// announced on the bus like every runtime's.
+	controller := connect(t, "mesh-controller", "bench")
+	out := func(s string) map[string]any { return map[string]any{"output": s, "ok": true} }
+	serve := func(verb string, answer func() any) {
+		stop, err := controller.HandleSubject("mesh.seat.mesh-controller.tool."+verb, func(json.RawMessage) (any, error) {
+			return answer(), nil
+		})
+		if err != nil {
+			t.Fatal(err)
+		}
+		t.Cleanup(stop)
+	}
+	serve("nodes", func() any {
+		return out("the bus's user list leaves out 2 user(s)\n" +
+			`[{"name":"bench","heard":"3m ago","mode":"converged","id":"1f2e"},{"name":"desk","heard":"here","mode":"converged","id":"9a8b"}]`)
+	})
+	var gammaOn atomic.Value
+	gammaOn.Store("[]")
+	serve("modules", func() any {
+		return out(fmt.Sprintf(`[{"module":"alpha","on":["desk"],"tools":true},{"module":"beta","on":["desk"],"tools":true},`+
+			`{"module":"gamma","on":%s,"tools":true},{"module":"delta","on":["desk"],"tools":false},`+
+			`{"module":"epsilon","on":["bench"],"tools":true},{"module":"mesh-controller","on":["bench"],"tools":true}]`, gammaOn.Load().(string)))
+	})
+	stopAnn, err := announce.Serve(controller, announce.Service{Name: "mesh-controller", ID: "bench"}, func() []announce.Endpoint {
+		return []announce.Endpoint{{Kind: announce.KindSeat, Module: "mesh-controller", Seat: "mesh-controller", Scope: "mesh",
+			// As the live controller announces: a mesh seat's holder names no machine.
+			Tool: "nodes", Node: "", Description: "Every machine the mesh knows.", Schema: json.RawMessage(`{}`),
+			Subject: "mesh.seat.mesh-controller.tool.nodes"}}
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(stopAnn)
+	controller.Flush()
+	watcher.Flush()
+
+	up, err := Serve(NewSurface(nodeTools, "desk.node-tools"), "127.0.0.1:0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer up.Close()
+	endpoint := "http://" + up.Address + "/mcp"
+
+	// Five tools, nothing else.
+	listed := post(t, endpoint, `{"jsonrpc":"2.0","id":2,"method":"tools/list"}`)["result"].(map[string]any)
+	var names []string
+	for _, x := range listed["tools"].([]any) {
+		name := x.(map[string]any)["name"].(string)
+		names = append(names, name)
+		for _, r := range name {
+			if !(r >= 'a' && r <= 'z' || r >= 'A' && r <= 'Z' || r >= '0' && r <= '9' || r == '_' || r == '-') || len(name) > 64 {
+				t.Errorf("%q is not a name the API takes", name)
+			}
+		}
+	}
+	if got := strings.Join(names, ","); got != "mesh_overview,mesh_machine,mesh_search,mesh_describe,mesh_call" {
+		t.Errorf("announced %s", got)
+	}
+
+	// The overview names the mesh's seats, the machines' seats and the machines.
+	overview, isErr := call(t, endpoint, "mesh_overview", nil)
+	if isErr || !strings.Contains(overview, "mesh-controller.nodes") || !strings.Contains(overview, "<node>/node-shelf.list") ||
+		!strings.Contains(overview, `"bench"`) || !strings.Contains(overview, `"desk"`) {
+		t.Errorf("overview: %s", overview)
+	}
+	// Silence is named only where tools should have answered: epsilon declares tools on bench and
+	// nothing there announced it; delta declares none and is never a name.
+	if strings.Contains(overview, "mesh-controller on bench") {
+		t.Errorf("a mesh seat's holder that announced no machine is called silent on its machine:\n%s", overview)
+	}
+	if !strings.Contains(overview, "epsilon on bench") || strings.Contains(overview, "delta") {
+		t.Errorf("not answering: %s", overview)
+	}
+	machine, isErr := call(t, endpoint, "mesh_machine", map[string]any{"node": "desk"})
+	if isErr || !strings.Contains(machine, "desk/node-shelf.list") || !strings.Contains(machine, "desk/beta.three") ||
+		!strings.Contains(machine, "desk/alpha.one") {
+		t.Errorf("machine: %s", machine)
+	}
+
+	// A mesh seat, a node seat, an assignment and an interchangeable module, each by address.
+	if got, isErr := call(t, endpoint, "mesh_call", map[string]any{"address": "mesh-controller.nodes"}); isErr || !strings.Contains(got, "converged") {
+		t.Errorf("mesh seat: %s", got)
+	}
+	if got, isErr := call(t, endpoint, "mesh_call", map[string]any{"address": "desk/node-shelf.list"}); isErr || !strings.Contains(got, `"a"`) {
+		t.Errorf("node seat: %s", got)
+	}
+	if got, isErr := call(t, endpoint, "mesh_call", map[string]any{"address": "desk/beta.three"}); isErr ||
+		!strings.Contains(got, `"beta": 3`) || !strings.Contains(got, "answered by desk") {
+		t.Errorf("assignment: %s", got)
+	}
+	if got, isErr := call(t, endpoint, "mesh_call", map[string]any{"address": "alpha.one"}); isErr || !strings.Contains(got, `"alpha": 1`) {
+		t.Errorf("interchangeable module: %s", got)
+	}
+
+	// Refused, by name, where the address does not say enough or says the wrong thing.
+	for address, want := range map[string]string{
+		"beta.three":                 "keeps state on each machine it runs on, so a call names the machine: write <node>/beta.three — it runs on desk",
+		"node-shelf.list":            "held once per machine: write <node>/node-shelf.list — it is held on desk",
+		"desk/mesh-controller.nodes": "held once for the whole mesh",
+		"bench/beta.three":           "beta does not run on bench; it runs on desk",
+		"nonsense":                   "is not an address",
+	} {
+		got, isErr := call(t, endpoint, "mesh_call", map[string]any{"address": address})
+		if !isErr || !strings.Contains(got, want) {
+			t.Errorf("%s: %s (want %q)", address, got, want)
+		}
+	}
+
+	// Described without `node`: the address carries the machine.
+	described, isErr := call(t, endpoint, "mesh_describe", map[string]any{"address": "desk/beta.three"})
+	if isErr || strings.Contains(described, `"node"`) || !strings.Contains(described, `"address": "desk/beta.three"`) {
+		t.Errorf("describe: %s", described)
+	}
+
+	// Search finds across the layers; a module that starts serving after the first answer is found.
+	if got, _ := call(t, endpoint, "mesh_search", map[string]any{"query": "shelf"}); !strings.Contains(got, "desk/node-shelf.list") {
+		t.Errorf("search a node seat: %s", got)
+	}
+	if got, _ := call(t, endpoint, "mesh_search", map[string]any{"query": "gamma"}); strings.Contains(got, "gamma.given") {
+		t.Fatalf("gamma was found before it served: %s", got)
+	}
+	mesh.Issue(t, mt.MembershipOf("gamma", "desk", false, nil))
+	gammaOn.Store(`["desk"]`)
+	late := connect(t, "node-tools", "desk")
+	stopLate, err := runtime.Run(late, []runtime.Served{{Module: "gamma", Entrypoints: []string{mt.Fixture("env-gamma.serve.mjs")}}},
+		nil, (&mt.Logs{}).Logf)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer stopLate()
+	var found string
+	for i := 0; i < 30; i++ {
+		found, _ = call(t, endpoint, "mesh_search", map[string]any{"query": "gamma given"})
+		if strings.Contains(found, "desk/gamma.given") {
+			break
+		}
+		time.Sleep(100 * time.Millisecond)
+	}
+	if !strings.Contains(found, "desk/gamma.given") {
+		t.Errorf("a module that arrived later was not found: %s", found)
+	}
+
+	if n := asked.Load(); n != 0 {
+		t.Errorf("discovery asked a roster or a module's tools %d time(s); it asks the bus", n)
+	}
+
+	// The old names still answer, unannounced.
+	if got, isErr := call(t, endpoint, "alpha.one", nil); isErr || !strings.Contains(got, `"alpha": 1`) {
+		t.Errorf("an old name: %s", got)
+	}
+}
+
+func TestTheControllersRecordsAreReadAsJSON(t *testing.T) {
+	if got := jsonIn("a warning printed first\n[{\"name\":\"ace\"}]"); got != `[{"name":"ace"}]` {
+		t.Errorf("an array after a warning: %q", got)
+	}
+	if got := jsonIn(`{"seats":[]}`); got != `{"seats":[]}` {
+		t.Errorf("an object: %q", got)
+	}
+}

node-tools/internal/console/client.go

@@ -0,0 +1,139 @@
+package console
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"regexp"
+	"strings"
+
+	"github.com/novox/mesh-tools/node-tools/internal/bus"
+)
+
+// Tool is a tool as its module — or, for a role's tool, the mesh's records — describes it.
+type Tool struct {
+	Module      string
+	Name        string
+	Description string
+	Input       json.RawMessage
+	Seat        bool
+	Scope       string
+	Subjects    []string
+}
+
+// Listing is what the mesh could say about its tools; silence is named, never dropped (design 34 §3).
+type Listing struct {
+	Tools        []Tool
+	NotAnswering []string
+}
+
+// Seats is the seats and their verbs, so `<seat>.<verb>` resolves to the role.
+type Seats map[string]map[string]bool
+
+func seatsIn(l *Listing) Seats {
+	out := Seats{}
+	for _, t := range l.Tools {
+		if !t.Seat {
+			continue
+		}
+		if out[t.Module] == nil {
+			out[t.Module] = map[string]bool{}
+		}
+		out[t.Module][t.Name] = true
+	}
+	return out
+}
+
+// toolKey is the key a call uses: a role's when the prefix is a seat declaring that verb.
+func toolKey(name string, seats Seats) string {
+	if strings.HasPrefix(name, "seat:") {
+		return name
+	}
+	dot := strings.Index(name, ".")
+	if dot < 0 {
+		return name
+	}
+	if seats[name[:dot]][name[dot+1:]] {
+		return "seat:" + name
+	}
+	return name
+}
+
+// toolsOn is the flat catalogue (MESH_CONSOLE_FLAT=1): what announced itself on the bus, every
+// tool and seat verb, and the assignments with tools that did not (novox/hq ADR 0197).
+func toolsOn(conn *bus.Conn) (*Listing, error) {
+	x, err := indexOn(conn)
+	if err != nil {
+		return nil, err
+	}
+	return x.Listing, nil
+}
+
+// callTool calls `<module>.<tool>[@<node>]`, on the subject the listing names for it when it names one.
+func callTool(conn *bus.Conn, key string, args any, seats Seats, l *Listing) (bus.Answered, error) {
+	name, node, _ := strings.Cut(key, "@")
+	if !strings.Contains(name, ".") {
+		return bus.Answered{}, fmt.Errorf("%q does not name a tool: write <module>.<tool>, as `mesh tools` lists "+
+			"them, or <module>.<tool>@<node> for the instance on one machine", key)
+	}
+	resolved := toolKey(name, seats)
+	if node != "" {
+		resolved += "@" + node
+	}
+	return conn.Ask(resolved, args, subjectListed(name, node, l))
+}
+
+func subjectListed(name, node string, l *Listing) string {
+	if l == nil {
+		return ""
+	}
+	dot := strings.Index(name, ".")
+	module, tool := name[:dot], name[dot+1:]
+	for _, t := range l.Tools {
+		if t.Module == module && t.Name == tool && !t.Seat {
+			if len(t.Subjects) == 0 {
+				return ""
+			}
+			if node == "" {
+				return t.Subjects[0]
+			}
+			for _, s := range t.Subjects {
+				if strings.HasSuffix(s, "."+node) {
+					return s
+				}
+			}
+			return ""
+		}
+	}
+	return ""
+}
+
+var (
+	noResponders = regexp.MustCompile(`(?i)no responders|503`)
+	refused      = regexp.MustCompile(`(?i)permissions violation|authorization`)
+	timedOut     = regexp.MustCompile(`(?i)timeout`)
+)
+
+// whyItFailed says why a call failed, so the remedy is in the words.
+func whyItFailed(key string, err error) string {
+	if err == nil {
+		err = errors.New("failed")
+	}
+	msg := err.Error()
+	switch {
+	case noResponders.MatchString(msg):
+		extra := ""
+		if strings.HasPrefix(key, "seat:") {
+			extra = ", or nothing holds that seat"
+		}
+		return "nothing serves " + key + ". The module may not be assigned to any machine, or it is down" +
+			extra + " — `mesh tools` lists what answered."
+	case refused.MatchString(msg):
+		return "this account may not call " + key + ". What it may call was fixed when it was issued — a " +
+			"person's by `operator issue`, the console's by its manifest."
+	case timedOut.MatchString(msg):
+		return key + " did not answer in time. Something is serving it, so this is the tool being slow " +
+			"rather than absent."
+	}
+	return key + " failed: " + msg
+}

node-tools/internal/console/console_test.go

@@ -0,0 +1,131 @@
+package console
+
+import (
+	"bytes"
+	"encoding/json"
+	"io"
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/novox/mesh-tools/node-tools/internal/bus"
+	mt "github.com/novox/mesh-tools/node-tools/internal/meshtest"
+	"github.com/novox/mesh-tools/node-tools/internal/runtime"
+)
+
+func connect(t *testing.T, module, node string) *bus.Conn {
+	t.Helper()
+	c, err := bus.Connect(bus.Credential{URL: mt.URL(t), Module: module, Node: node})
+	if err != nil {
+		t.Fatal(err)
+	}
+	c.Logf = func(string, ...any) {}
+	t.Cleanup(c.Close)
+	return c
+}
+
+func post(t *testing.T, endpoint string, body string) map[string]any {
+	t.Helper()
+	res, err := http.Post(endpoint, "application/json", bytes.NewBufferString(body))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer res.Body.Close()
+	raw, _ := io.ReadAll(res.Body)
+	var out map[string]any
+	if err := json.Unmarshal(raw, &out); err != nil {
+		t.Fatalf("%d %s", res.StatusCode, raw)
+	}
+	return out
+}
+
+// As node-tools, the runtime serves the bundles and is the console on loopback: the listing is what
+// the modules and the mesh's records answered, and a call reaches the module on the machine named.
+func TestTheConsoleListsAndCallsOverHTTP(t *testing.T) {
+	mesh := mt.New(t)
+	mesh.Issue(t, mt.MembershipOf("alpha", "desk", true, nil))
+	mesh.Issue(t, mt.MembershipOf("beta", "desk", false, map[string][]string{"node-shelf": {"list", "clear"}}))
+	nodeTools := connect(t, "node-tools", "desk")
+	stop, err := runtime.Run(nodeTools, []runtime.Served{
+		{Module: "alpha", Entrypoints: []string{mt.Fixture("many-alpha.serve.mjs")}},
+		{Module: "beta", Entrypoints: []string{mt.Fixture("many-beta.serve.mjs")}},
+	}, nil, (&mt.Logs{}).Logf)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer stop()
+
+	// The controller's records (ADR 0197): ghost declares tools on desk and nothing announces it.
+	controller := connect(t, "mesh-controller", "")
+	stopSeat, _ := controller.HandleSubject("mesh.seat.mesh-controller.tool.modules", func(json.RawMessage) (any, error) {
+		return map[string]any{"ok": true, "output": `[{"module":"alpha","on":["desk"],"tools":true},` +
+			`{"module":"beta","on":["desk"],"tools":true},{"module":"ghost","on":["desk"],"tools":true}]`}, nil
+	})
+	defer stopSeat()
+	controller.Flush()
+
+	flat := NewSurface(nodeTools, "desk.node-tools")
+	flat.Flat = true // the whole catalogue, as before ADR 0195: still reachable, no longer announced
+	up, err := Serve(flat, "127.0.0.1:0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer up.Close()
+	endpoint := "http://" + up.Address + "/mcp"
+
+	init := post(t, endpoint, `{"jsonrpc":"2.0","id":1,"method":"initialize","params":{"protocolVersion":"2025-03-26","capabilities":{}}}`)
+	if !strings.Contains(init["result"].(map[string]any)["instructions"].(string), "reached as desk.node-tools") {
+		t.Errorf("initialize: %v", init)
+	}
+	listed := post(t, endpoint, `{"jsonrpc":"2.0","id":2,"method":"tools/list"}`)["result"].(map[string]any)
+	var names []string
+	for _, x := range listed["tools"].([]any) {
+		names = append(names, x.(map[string]any)["name"].(string))
+	}
+	if got := strings.Join(names, ","); got != "alpha.one,alpha.two,beta.five,beta.four,beta.three,node-shelf.clear,node-shelf.list" {
+		t.Errorf("listed %s", got)
+	}
+	if got := listed["_meta"].(map[string]any)["notAnswering"]; len(got.([]any)) != 1 || got.([]any)[0] != "ghost on desk" {
+		t.Errorf("not answering: %v", got)
+	}
+	for _, x := range listed["tools"].([]any) {
+		tool := x.(map[string]any)
+		if tool["name"] == "node-shelf.list" {
+			schema := tool["inputSchema"].(map[string]any)
+			if req, _ := schema["required"].([]any); len(req) != 1 || req[0] != "node" {
+				t.Errorf("a node seat's verb does not require node: %v", schema)
+			}
+		}
+	}
+
+	called := post(t, endpoint, `{"jsonrpc":"2.0","id":3,"method":"tools/call","params":{"name":"alpha.one","arguments":{"node":"desk"}}}`)
+	content := called["result"].(map[string]any)["content"].([]any)
+	var got map[string]any
+	_ = json.Unmarshal([]byte(content[0].(map[string]any)["text"].(string)), &got)
+	if got["alpha"] != float64(1) || content[1].(map[string]any)["text"] != "answered by desk" {
+		t.Errorf("called: %v", called)
+	}
+	seat := post(t, endpoint, `{"jsonrpc":"2.0","id":4,"method":"tools/call","params":{"name":"node-shelf.list","arguments":{"node":"desk"}}}`)
+	if text := seat["result"].(map[string]any)["content"].([]any)[0].(map[string]any)["text"].(string); !strings.Contains(text, `"a"`) {
+		t.Errorf("seat verb: %v", seat)
+	}
+	refused := post(t, endpoint, `{"jsonrpc":"2.0","id":5,"method":"tools/call","params":{"name":"node-shelf.list","arguments":{}}}`)
+	if refused["error"] == nil {
+		t.Errorf("a node seat's verb was called without its machine: %v", refused)
+	}
+	absent := post(t, endpoint, `{"jsonrpc":"2.0","id":6,"method":"tools/call","params":{"name":"ghost.boo","arguments":{}}}`)
+	result := absent["result"].(map[string]any)
+	if result["isError"] != true || !strings.Contains(result["content"].([]any)[0].(map[string]any)["text"].(string), "nothing serves ghost.boo") {
+		t.Errorf("an absent tool: %v", absent)
+	}
+	res, err := http.Post(endpoint, "application/json", strings.NewReader(`{"jsonrpc":"2.0","method":"notifications/initialized"}`))
+	if err != nil || res.StatusCode != 202 {
+		t.Errorf("a notification: %v %v", res, err)
+	}
+}
+
+func TestTheConsoleListensOnLoopbackAndNowhereElse(t *testing.T) {
+	if _, err := Serve(NewSurface(nil, "x"), "0.0.0.0:0"); err == nil || !strings.Contains(err.Error(), "loopback and nowhere else") {
+		t.Errorf("a non-loopback console was not refused: %v", err)
+	}
+}

node-tools/internal/console/http.go

@@ -0,0 +1,125 @@
+package console
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"strconv"
+	"strings"
+
+	"github.com/novox/mesh-tools/node-tools/internal/wire"
+)
+
+// bodyLimit is the most a request body may be.
+const bodyLimit = 1 << 20
+
+var loopback = map[string]bool{"127.0.0.1": true, "::1": true, "localhost": true, "[::1]": true}
+
+// Listening is a console that listens: where, with the port the machine gave, and how to stop it.
+type Listening struct {
+	Address string
+	Close   func() error
+}
+
+// Serve listens on host:port, refused unless the host is loopback — said before binding, so a
+// console that would open to a network is a startup failure (ADR 0152).
+func Serve(s *Surface, listen string) (*Listening, error) {
+	at := strings.LastIndex(listen, ":")
+	if at < 0 {
+		return nil, fmt.Errorf("%q is not host:port", listen)
+	}
+	host, portText := listen[:at], listen[at+1:]
+	if !loopback[host] {
+		return nil, fmt.Errorf(`the console listens on loopback and nowhere else (novox/hq ADR 0152): %q is not this `+
+			"machine's own address — whoever is on the machine owns the mesh there, and nobody else may reach this", host)
+	}
+	port, err := strconv.Atoi(portText)
+	if err != nil || port < 0 || port > 65535 {
+		return nil, fmt.Errorf("%q is not a port", portText)
+	}
+	ln, err := net.Listen("tcp", net.JoinHostPort(strings.Trim(host, "[]"), portText))
+	if err != nil {
+		return nil, err
+	}
+	server := &http.Server{Handler: http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { route(w, r, s) })}
+	go func() { _ = server.Serve(ln) }()
+	bound := ln.Addr().(*net.TCPAddr).Port
+	return &Listening{Address: host + ":" + strconv.Itoa(bound), Close: func() error { return server.Shutdown(context.Background()) }}, nil
+}
+
+func route(w http.ResponseWriter, r *http.Request, s *Surface) {
+	switch r.URL.Path {
+	case "/":
+		w.Header().Set("content-type", "text/plain; charset=utf-8")
+		_, _ = io.WriteString(w, "the mesh's console: MCP over HTTP at POST /mcp (novox/hq design 34)\n")
+		return
+	case "/mcp":
+	default:
+		writeJSON(w, 404, map[string]any{"error": "the console serves /mcp and nothing else"})
+		return
+	}
+	switch r.Method {
+	case http.MethodPost:
+	case http.MethodDelete:
+		w.WriteHeader(204) // no session to end
+		return
+	default:
+		w.Header().Set("allow", "POST, DELETE")
+		w.WriteHeader(405)
+		return
+	}
+	body, err := io.ReadAll(io.LimitReader(r.Body, bodyLimit+1))
+	if err != nil || len(body) > bodyLimit {
+		if err == nil {
+			err = fmt.Errorf("the request is larger than %d bytes", bodyLimit)
+		}
+		writeJSON(w, 413, map[string]any{"jsonrpc": "2.0", "id": nil, "error": map[string]any{"code": -32600, "message": err.Error()}})
+		return
+	}
+	trimmed := strings.TrimSpace(string(body))
+	if strings.HasPrefix(trimmed, "[") {
+		var batch []Request
+		if err := json.Unmarshal(body, &batch); err != nil {
+			writeJSON(w, 400, map[string]any{"jsonrpc": "2.0", "id": nil, "error": map[string]any{"code": -32700, "message": "the body is not JSON"}})
+			return
+		}
+		replies := []*Reply{}
+		for _, req := range batch {
+			if reply := s.Handle(req); reply != nil {
+				replies = append(replies, reply)
+			}
+		}
+		if len(replies) == 0 {
+			w.WriteHeader(202)
+			return
+		}
+		writeJSON(w, 200, replies)
+		return
+	}
+	var req Request
+	if err := json.Unmarshal(body, &req); err != nil {
+		writeJSON(w, 400, map[string]any{"jsonrpc": "2.0", "id": nil, "error": map[string]any{"code": -32700, "message": "the body is not JSON"}})
+		return
+	}
+	reply := s.Handle(req)
+	if reply == nil {
+		w.WriteHeader(202)
+		return
+	}
+	writeJSON(w, 200, reply)
+}
+
+func writeJSON(w http.ResponseWriter, status int, body any) {
+	text, err := wire.Marshal(body)
+	if err != nil {
+		text, _ = json.Marshal(map[string]any{"error": errors.New("unencodable answer").Error()})
+	}
+	w.Header().Set("content-type", "application/json; charset=utf-8")
+	w.Header().Set("content-length", strconv.Itoa(len(text)))
+	w.WriteHeader(status)
+	_, _ = w.Write(text)
+}

node-tools/internal/console/mcp.go

@@ -0,0 +1,297 @@
+// Package console is the mesh's tools as an MCP server on a machine's loopback (novox/hq design 34,
+// ADR 0152, ADR 0175 §6): the Go port of node-tools' http.ts, mcp.ts and client.ts. A thin adapter:
+// every tool listed is one a module answered for, the schema is the module's, the answer the module's.
+package console
+
+import (
+	"encoding/json"
+	"os"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/novox/mesh-tools/node-tools/internal/bus"
+)
+
+// Protocol is the MCP version spoken to an agent host.
+const Protocol = "2025-03-26"
+
+// ListingKept is how long a fetched tool list is kept before the modules are asked again.
+var ListingKept = 30 * time.Second
+
+// Request is one JSON-RPC message from a host.
+type Request struct {
+	JSONRPC string          `json:"jsonrpc"`
+	ID      json.RawMessage `json:"id,omitempty"`
+	Method  string          `json:"method"`
+	Params  json.RawMessage `json:"params,omitempty"`
+}
+
+// Reply is one JSON-RPC answer.
+type Reply struct {
+	JSONRPC string          `json:"jsonrpc"`
+	ID      json.RawMessage `json:"id"`
+	Result  any             `json:"result,omitempty"`
+	Error   *RPCError       `json:"error,omitempty"`
+}
+
+// RPCError is a protocol-level refusal.
+type RPCError struct {
+	Code    int    `json:"code"`
+	Message string `json:"message"`
+}
+
+// Surface answers MCP requests over one bus connection, as one account.
+type Surface struct {
+	conn  *bus.Conn
+	who   string
+	mu    sync.Mutex
+	known *Listing
+	at    time.Time
+	idx   *index
+	idxAt time.Time
+	// Flat announces the whole catalogue, as the console did before ADR 0195: for a person reading
+	// it or a client that wants it. Off by default; MESH_CONSOLE_FLAT=1 turns it on.
+	Flat bool
+}
+
+// NewSurface is the surface over a connection, as `who`.
+func NewSurface(conn *bus.Conn, who string) *Surface {
+	return &Surface{conn: conn, who: who, Flat: os.Getenv("MESH_CONSOLE_FLAT") == "1"}
+}
+
+func (s *Surface) listing() (*Listing, error) {
+	s.mu.Lock()
+	if s.known != nil && time.Since(s.at) <= ListingKept {
+		l := s.known
+		s.mu.Unlock()
+		return l, nil
+	}
+	s.mu.Unlock()
+	l, err := toolsOn(s.conn)
+	if err != nil {
+		return nil, err
+	}
+	s.mu.Lock()
+	s.known, s.at = l, time.Now()
+	s.mu.Unlock()
+	return l, nil
+}
+
+func isNotification(id json.RawMessage) bool {
+	t := strings.TrimSpace(string(id))
+	return t == "" || t == "null"
+}
+
+func answer(id json.RawMessage, result any) *Reply {
+	return &Reply{JSONRPC: "2.0", ID: idOrNull(id), Result: result}
+}
+
+func refuse(id json.RawMessage, code int, message string) *Reply {
+	return &Reply{JSONRPC: "2.0", ID: idOrNull(id), Error: &RPCError{Code: code, Message: message}}
+}
+
+func idOrNull(id json.RawMessage) json.RawMessage {
+	if isNotification(id) {
+		return json.RawMessage("null")
+	}
+	return id
+}
+
+// Handle answers one request; nil for a notification, which expects none.
+func (s *Surface) Handle(r Request) *Reply {
+	notification := isNotification(r.ID)
+	switch r.Method {
+	case "initialize":
+		return answer(r.ID, map[string]any{
+			"protocolVersion": Protocol,
+			"capabilities":    map[string]any{"tools": map[string]any{}},
+			"serverInfo":      map[string]any{"name": "mesh", "version": "1"},
+			"instructions":    s.instructions(),
+		})
+	case "notifications/initialized":
+		return nil
+	case "ping":
+		if notification {
+			return nil
+		}
+		return answer(r.ID, map[string]any{})
+	case "tools/list":
+		if !s.Flat {
+			return answer(r.ID, map[string]any{"tools": discovery()})
+		}
+		l, err := s.listing()
+		if err != nil {
+			return refuse(r.ID, -32603, "the mesh's discovery failed: "+err.Error())
+		}
+		tools := make([]map[string]any, 0, len(l.Tools))
+		for _, t := range l.Tools {
+			var schema map[string]any
+			switch {
+			case t.Seat && t.Scope != "node":
+				schema = asSchema(t.Input)
+			case t.Seat:
+				schema = withNode(asSchema(t.Input), "the machine whose seat answers; required, the seat is held once per machine", true)
+			default:
+				schema = withNode(asSchema(t.Input), "", false)
+			}
+			description := t.Description
+			if description == "" {
+				description = t.Name + ", served by " + t.Module
+			}
+			tools = append(tools, map[string]any{"name": t.Module + "." + t.Name, "description": description, "inputSchema": schema})
+		}
+		return answer(r.ID, map[string]any{"tools": tools, "_meta": map[string]any{"notAnswering": l.NotAnswering}})
+	case "tools/call":
+		var p struct {
+			Name      string         `json:"name"`
+			Arguments map[string]any `json:"arguments"`
+		}
+		_ = json.Unmarshal(r.Params, &p)
+		if isDiscovery(p.Name) {
+			if p.Arguments == nil {
+				p.Arguments = map[string]any{}
+			}
+			return answer(r.ID, s.discover(p.Name, p.Arguments))
+		}
+		args := map[string]any{}
+		for k, v := range p.Arguments {
+			args[k] = v
+		}
+		l, _ := s.listing()
+		var roles Seats
+		if l != nil {
+			roles = seatsIn(l)
+		}
+		bare, _, _ := strings.Cut(p.Name, "@")
+		isSeatVerb := roles != nil && strings.HasPrefix(toolKey(bare, roles), "seat:")
+		nodeScoped := false
+		if isSeatVerb && l != nil {
+			for _, t := range l.Tools {
+				if t.Seat && t.Scope == "node" && t.Module+"."+t.Name == bare {
+					nodeScoped = true
+				}
+			}
+		}
+		takesNode := !isSeatVerb || nodeScoped
+		node := ""
+		if takesNode {
+			if n, ok := args["node"].(string); ok {
+				node = n
+			}
+			delete(args, "node")
+		}
+		if nodeScoped && node == "" && !strings.Contains(p.Name, "@") {
+			return refuse(r.ID, -32602, p.Name+" is a machine's seat's verb: name the machine with `node`")
+		}
+		name := p.Name
+		if node != "" && !strings.Contains(p.Name, "@") {
+			name = p.Name + "@" + node
+		}
+		got, err := callTool(s.conn, name, args, roles, l)
+		if err != nil {
+			return answer(r.ID, map[string]any{
+				"content": []map[string]any{{"type": "text", "text": whyItFailed(name, err)}},
+				"isError": true,
+			})
+		}
+		content := []map[string]any{{"type": "text", "text": pretty(got.Result)}}
+		if got.Node != "" {
+			content = append(content, map[string]any{"type": "text", "text": "answered by " + got.Node})
+		}
+		return answer(r.ID, map[string]any{"content": content})
+	}
+	if notification {
+		return nil
+	}
+	return refuse(r.ID, -32601, "mesh's MCP surface has no "+r.Method)
+}
+
+// pretty is a module's answer as JSON text, indented as JSON.stringify(result, null, 2) writes it.
+func pretty(raw json.RawMessage) string {
+	if len(raw) == 0 {
+		return "null"
+	}
+	var v any
+	if json.Unmarshal(raw, &v) != nil {
+		return string(raw)
+	}
+	b, err := json.MarshalIndent(v, "", "  ")
+	if err != nil {
+		return string(raw)
+	}
+	return strings.NewReplacer(`<`, "<", `>`, ">", `&`, "&").Replace(string(b))
+}
+
+// asSchema is a module's declared input as a JSON schema: wrapped when it is a bare map of
+// properties, passed through when it is a schema, empty when nothing was declared.
+func asSchema(raw json.RawMessage) map[string]any {
+	var given map[string]any
+	if json.Unmarshal(raw, &given) != nil || given == nil {
+		return map[string]any{"type": "object", "properties": map[string]any{}}
+	}
+	if given["type"] == "object" {
+		return given
+	}
+	if _, has := given["properties"]; has {
+		return given
+	}
+	if len(given) == 0 {
+		return map[string]any{"type": "object", "properties": map[string]any{}}
+	}
+	return map[string]any{"type": "object", "properties": given}
+}
+
+// withNode adds the optional — or, for a node seat, required — `node` argument (ADR 0159).
+func withNode(schema map[string]any, description string, required bool) map[string]any {
+	properties := map[string]any{}
+	if p, ok := schema["properties"].(map[string]any); ok {
+		for k, v := range p {
+			properties[k] = v
+		}
+	}
+	if _, has := properties["node"]; !has {
+		if description == "" {
+			description = "the machine to ask, when this module runs on several; else whichever answers, and the answer says which"
+		}
+		properties["node"] = map[string]any{"type": "string", "description": description}
+	}
+	out := map[string]any{}
+	for k, v := range schema {
+		out[k] = v
+	}
+	out["type"] = "object"
+	out["properties"] = properties
+	if required {
+		have := []any{}
+		if r, ok := schema["required"].([]any); ok {
+			have = r
+		}
+		hasNode := false
+		for _, x := range have {
+			hasNode = hasNode || x == "node"
+		}
+		if !hasNode {
+			have = append(have, "node")
+		}
+		out["required"] = have
+	}
+	return out
+}
+
+// instructions is what an agent host is told about this surface when it connects.
+func (s *Surface) instructions() string {
+	if s.Flat {
+		return "These are the tools of a Novox mesh, reached as " + s.who + ". Every call goes to the module " +
+			"that serves it; what may be called was fixed when this account was issued, so a " +
+			"refusal means the account, not the tool. The list is what the running modules " +
+			"answered, plus every role's tools from the mesh's records — the mesh's own verbs " +
+			"(mesh-controller.status, .push, .assign …) among them; a module that did not answer " +
+			"is named in the list's _meta and can still be called by <module>.<tool>."
+	}
+	return "The tools of a Novox mesh, reached as " + s.who + ", found by address rather than listed " +
+		"whole (novox/hq ADR 0195). mesh_overview shows the mesh's seats and machines; mesh_machine one " +
+		"machine's seats and modules; mesh_search finds a tool by words; mesh_describe gives one tool's " +
+		"arguments; mesh_call calls it. " + grammar + " What may be called was fixed when this account " +
+		"was issued, so a refusal means the account, not the tool."
+}

node-tools/internal/launch/launch.go

@@ -0,0 +1,511 @@
+// Package launch starts a bundle the runtime serves and speaks MCP over stdio to it (novox/hq ADR
+// 0188, ADR 0193): `initialize`, `tools/list` once, `tools/call` per call. A Go binary, a Python
+// script and a Node launcher are the same thing here: an executable that answers those. The runtime
+// knows no language; it starts the path it is given.
+package launch
+
+import (
+	"bufio"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"regexp"
+	"strings"
+	"sync"
+	"syscall"
+	"time"
+
+	"golang.org/x/sys/unix"
+
+	"github.com/novox/mesh-tools/node-tools/internal/wire"
+)
+
+// Protocol is the MCP version spoken to a bundle.
+const Protocol = "2025-03-26"
+
+// How long a child has for its handshake, and a call before the caller is told it is slow.
+var (
+	HandshakeTimeout = 10 * time.Second
+	CallTimeout      = 30 * time.Second
+)
+
+// Tool is one tool a launched bundle listed, and how to call it.
+type Tool struct {
+	Name        string
+	Description string
+	Input       json.RawMessage
+	Run         func(args json.RawMessage) (json.RawMessage, error)
+}
+
+// Registration is the tools a bundle listed under one name: its module's, or a seat's.
+type Registration struct {
+	Module string
+	Tools  []Tool
+}
+
+// Bus is what a launched bundle reaches the mesh through (novox/hq ADR 0193, ADR 0198): the runtime
+// publishes, asks and subscribes on the module's behalf. Subscribe is asked each time the module's
+// code subscribes; the runtime binds the module's consumer once and calls deliver for every event,
+// acknowledging it on the bus when deliver returns nil.
+type Bus interface {
+	Publish(params json.RawMessage) error
+	Ask(params json.RawMessage) (json.RawMessage, error)
+	Subscribe(deliver func(envelope json.RawMessage) error) error
+}
+
+// EventTimeout bounds how long a bundle has to handle one event before it is offered again.
+var EventTimeout = 2 * time.Minute
+
+// Restart backoff: a bundle that exits is started again at once, then after growing pauses while it
+// keeps exiting, back to at once once it has run a while.
+var (
+	RestartFirst  = 500 * time.Millisecond
+	RestartMost   = 30 * time.Second
+	RestartSettle = time.Minute
+)
+
+// Launched is a running bundle: what it registered, and how to stop it.
+type Launched struct {
+	Registrations []Registration
+	Stop          func()
+}
+
+// Executable says whether an entrypoint can be started: a bundle the runtime serves is executable,
+// and one that is not was not built to be served (ADR 0193).
+func Executable(path string) bool {
+	info, err := os.Stat(path)
+	if err != nil || info.IsDir() {
+		return false
+	}
+	return info.Mode().Perm()&0o111 != 0
+}
+
+type message struct {
+	JSONRPC string          `json:"jsonrpc,omitempty"`
+	ID      json.RawMessage `json:"id,omitempty"`
+	Method  string          `json:"method,omitempty"`
+	Params  json.RawMessage `json:"params,omitempty"`
+	Result  json.RawMessage `json:"result,omitempty"`
+	Error   *struct {
+		Code    int    `json:"code"`
+		Message string `json:"message"`
+	} `json:"error,omitempty"`
+}
+
+type child struct {
+	cmd     *exec.Cmd
+	stdin   io.WriteCloser
+	writeMu sync.Mutex
+	mu      sync.Mutex
+	pending map[int64]chan message
+	next    int64
+	dead    chan struct{}
+	why     error
+}
+
+func (c *child) write(m any) error {
+	b, err := wire.Marshal(m)
+	if err != nil {
+		return err
+	}
+	c.writeMu.Lock()
+	defer c.writeMu.Unlock()
+	_, err = c.stdin.Write(append(b, '\n'))
+	return err
+}
+
+var stackLine = regexp.MustCompile(`^\s+at\s`)
+
+// Start launches one bundle and learns its tools. It fails when the child cannot be started or does
+// not complete the handshake. A child that exits later is started again on its next call.
+func Start(module, entry string, env []string, mesh Bus, logf func(string, ...any)) (*Launched, error) {
+	var mu sync.Mutex
+	var current *child
+	// The child that last subscribed is the one events are handed to: a restarted child subscribes
+	// again as its code is imported, and from then on the module's events are its.
+	var subscriber *child
+	stopped := false
+	deliver := func(envelope json.RawMessage) error {
+		mu.Lock()
+		c := subscriber
+		mu.Unlock()
+		if c == nil {
+			return errors.New(module + "'s bundle is not running to take its events")
+		}
+		_, err := c.ask(module, "mesh/event", map[string]any{"envelope": envelope}, EventTimeout)
+		return err
+	}
+	var restart func(after time.Duration)
+	var startedAt time.Time
+	pause := RestartFirst
+
+	start := func() (*child, error) {
+		cmd := exec.Command(entry)
+		cmd.Env = env
+		stdin, err := cmd.StdinPipe()
+		if err != nil {
+			return nil, err
+		}
+		stdout, err := cmd.StdoutPipe()
+		if err != nil {
+			return nil, err
+		}
+		stderr, err := cmd.StderrPipe()
+		if err != nil {
+			return nil, err
+		}
+		if err := cmd.Start(); err != nil {
+			return nil, err
+		}
+		c := &child{cmd: cmd, stdin: stdin, pending: map[int64]chan message{}, next: 1, dead: make(chan struct{})}
+		var lastSaid string
+		var saidMu sync.Mutex
+		stderrDone := make(chan struct{})
+		go func() {
+			defer close(stderrDone)
+			scan := bufio.NewScanner(stderr)
+			scan.Buffer(make([]byte, 64*1024), 1<<20)
+			for scan.Scan() {
+				line := scan.Text()
+				if strings.TrimSpace(line) == "" {
+					continue
+				}
+				logf("[%s] %s", module, line)
+				if !stackLine.MatchString(line) && !strings.HasPrefix(line, "Node.js v") {
+					saidMu.Lock()
+					lastSaid = strings.TrimSpace(line)
+					saidMu.Unlock()
+				}
+			}
+		}()
+		go func() {
+			scan := bufio.NewScanner(stdout)
+			scan.Buffer(make([]byte, 64*1024), 16<<20)
+			for scan.Scan() {
+				line := strings.TrimSpace(scan.Text())
+				if line == "" {
+					continue
+				}
+				var m message
+				if err := json.Unmarshal([]byte(line), &m); err != nil {
+					if len(line) > 120 {
+						line = line[:120]
+					}
+					logf("[mesh-tools] %s's bundle said something that is not a reply: %s", module, line)
+					continue
+				}
+				// The bundle asks the runtime (ADR 0193, ADR 0198): to emit, to call a tool, to hand it the
+				// module's events. Each on the module's behalf, answered when done; nothing else.
+				if m.Method != "" {
+					go func(m message) {
+						var result any = map[string]any{}
+						var err error
+						switch m.Method {
+						case "mesh/publish":
+							err = mesh.Publish(m.Params)
+						case "mesh/ask":
+							var asked json.RawMessage
+							if asked, err = mesh.Ask(m.Params); err == nil {
+								result = asked
+							}
+						case "mesh/subscribe":
+							mu.Lock()
+							subscriber = c
+							mu.Unlock()
+							err = mesh.Subscribe(deliver)
+						default:
+							if len(m.ID) > 0 {
+								_ = c.write(map[string]any{"jsonrpc": "2.0", "id": m.ID,
+									"error": map[string]any{"code": -32601, "message": "the runtime answers no " + m.Method + " from a bundle"}})
+							}
+							return
+						}
+						if len(m.ID) == 0 {
+							return
+						}
+						if err != nil {
+							_ = c.write(map[string]any{"jsonrpc": "2.0", "id": m.ID,
+								"error": map[string]any{"code": -32000, "message": err.Error()}})
+							return
+						}
+						_ = c.write(map[string]any{"jsonrpc": "2.0", "id": m.ID, "result": result})
+					}(m)
+					continue
+				}
+				var id int64
+				if json.Unmarshal(m.ID, &id) != nil {
+					continue
+				}
+				c.mu.Lock()
+				ch := c.pending[id]
+				delete(c.pending, id)
+				c.mu.Unlock()
+				if ch != nil {
+					ch <- m
+				}
+			}
+			<-stderrDone
+			err := cmd.Wait()
+			code := "0"
+			if exit := (*exec.ExitError)(nil); errors.As(err, &exit) {
+				if status, ok := exit.Sys().(syscall.WaitStatus); ok && status.Signaled() {
+					code = unix.SignalName(status.Signal())
+				} else {
+					code = fmt.Sprint(exit.ExitCode())
+				}
+			}
+			saidMu.Lock()
+			why := fmt.Sprintf("%s's bundle exited (%s)", module, code)
+			if lastSaid != "" {
+				why += ": " + lastSaid
+			}
+			saidMu.Unlock()
+			c.mu.Lock()
+			c.why = errors.New(why)
+			c.mu.Unlock()
+			close(c.dead)
+			mu.Lock()
+			// Only a child that was serving is brought back; one that died in its own handshake was
+			// never accepted, and whoever started it was told why.
+			wasServing := current == c
+			if current == c {
+				current = nil
+			}
+			if subscriber == c {
+				subscriber = nil
+			}
+			wasStopped := stopped
+			// Started again at once if it ran a while; after a growing pause while it keeps exiting.
+			wait := RestartFirst
+			if time.Since(startedAt) < RestartSettle {
+				wait = pause
+				if pause *= 2; pause > RestartMost {
+					pause = RestartMost
+				}
+			} else {
+				pause = RestartFirst
+			}
+			mu.Unlock()
+			if !wasStopped && wasServing {
+				// Every bundle stays up (ADR 0198): code that runs long — a handler, a provisioner —
+				// is not waiting for a call to bring it back, and a tool bundle back early costs nothing.
+				logf("[mesh-tools] %s; started again in %s", why, wait.Round(100*time.Millisecond))
+				restart(wait)
+			}
+		}()
+		if _, err := c.ask(module, "initialize", map[string]any{"protocolVersion": Protocol, "capabilities": map[string]any{},
+			"clientInfo": map[string]any{"name": "node-tools", "version": "1"}}, HandshakeTimeout); err != nil {
+			_ = cmd.Process.Kill()
+			return nil, err
+		}
+		_ = c.write(map[string]any{"jsonrpc": "2.0", "method": "notifications/initialized"})
+		return c, nil
+	}
+
+	asking := func(method string, params any, timeout time.Duration) (json.RawMessage, error) {
+		mu.Lock()
+		c := current
+		mu.Unlock()
+		if c == nil {
+			fresh, err := start()
+			if err != nil {
+				return nil, err
+			}
+			mu.Lock()
+			if current == nil {
+				current = fresh
+				startedAt = time.Now()
+			} else {
+				_ = fresh.cmd.Process.Signal(syscall.SIGTERM)
+				fresh = current
+			}
+			c = fresh
+			mu.Unlock()
+		}
+		return c.ask(module, method, params, timeout)
+	}
+
+	restart = func(after time.Duration) {
+		go func() {
+			time.Sleep(after)
+			mu.Lock()
+			if stopped || current != nil {
+				mu.Unlock()
+				return
+			}
+			mu.Unlock()
+			fresh, err := start()
+			mu.Lock()
+			defer mu.Unlock()
+			if err != nil {
+				if !stopped {
+					wait := pause
+					if pause *= 2; pause > RestartMost {
+						pause = RestartMost
+					}
+					logf("[mesh-tools] %s's bundle did not start again: %v; trying in %s", module, err, wait)
+					go restart(wait)
+				}
+				return
+			}
+			if stopped {
+				_ = fresh.cmd.Process.Signal(syscall.SIGTERM)
+				return
+			}
+			if current == nil {
+				current = fresh
+				startedAt = time.Now()
+			} else {
+				_ = fresh.cmd.Process.Signal(syscall.SIGTERM)
+			}
+		}()
+	}
+
+	first, err := start()
+	if err != nil {
+		return nil, err
+	}
+	mu.Lock()
+	current = first
+	startedAt = time.Now()
+	mu.Unlock()
+
+	raw, err := asking("tools/list", map[string]any{}, HandshakeTimeout)
+	if err != nil {
+		return nil, err
+	}
+	var listed struct {
+		Tools []struct {
+			Name        string          `json:"name"`
+			Description string          `json:"description"`
+			InputSchema json.RawMessage `json:"inputSchema"`
+		} `json:"tools"`
+	}
+	if err := json.Unmarshal(raw, &listed); err != nil {
+		return nil, fmt.Errorf("%s's bundle listed its tools in a shape that is not MCP's: %w", module, err)
+	}
+	order := []string{}
+	groups := map[string][]Tool{}
+	for _, t := range listed.Tools {
+		under, name := module, t.Name
+		if dot := strings.Index(t.Name, "."); dot >= 0 {
+			under, name = t.Name[:dot], t.Name[dot+1:]
+		}
+		full := t.Name
+		input := t.InputSchema
+		if len(input) == 0 || string(input) == "null" {
+			input = json.RawMessage("{}")
+		}
+		tool := Tool{Name: name, Description: t.Description, Input: input,
+			Run: func(args json.RawMessage) (json.RawMessage, error) {
+				if len(args) == 0 || string(args) == "null" {
+					args = json.RawMessage("{}")
+				}
+				res, err := asking("tools/call", map[string]any{"name": full, "arguments": args}, CallTimeout)
+				if err != nil {
+					return nil, err
+				}
+				var called struct {
+					Content []struct {
+						Type string `json:"type"`
+						Text string `json:"text"`
+					} `json:"content"`
+					IsError bool `json:"isError"`
+				}
+				_ = json.Unmarshal(res, &called)
+				text := ""
+				for _, c := range called.Content {
+					if c.Type == "text" {
+						text = c.Text
+						break
+					}
+				}
+				if called.IsError {
+					if text == "" {
+						text = module + "." + full + " failed"
+					}
+					return nil, errors.New(text)
+				}
+				// The bundle's answer is JSON as text; handed back as the value it encodes.
+				if json.Valid([]byte(text)) && text != "" {
+					return json.RawMessage(text), nil
+				}
+				b, _ := json.Marshal(text)
+				return b, nil
+			}}
+		if _, seen := groups[under]; !seen {
+			order = append(order, under)
+		}
+		groups[under] = append(groups[under], tool)
+	}
+	out := &Launched{Stop: func() {
+		mu.Lock()
+		stopped = true
+		c := current
+		current = nil
+		mu.Unlock()
+		if c != nil && c.cmd.Process != nil {
+			_ = c.cmd.Process.Signal(syscall.SIGTERM)
+		}
+	}}
+	for _, under := range order {
+		out.Registrations = append(out.Registrations, Registration{Module: under, Tools: groups[under]})
+	}
+	return out, nil
+}
+
+func (c *child) ask(module, method string, params any, timeout time.Duration) (json.RawMessage, error) {
+	c.mu.Lock()
+	if c.why != nil {
+		c.mu.Unlock()
+		return nil, c.why
+	}
+	id := c.next
+	c.next++
+	ch := make(chan message, 1)
+	c.pending[id] = ch
+	c.mu.Unlock()
+	if err := c.write(map[string]any{"jsonrpc": "2.0", "id": id, "method": method, "params": params}); err != nil {
+		c.mu.Lock()
+		delete(c.pending, id)
+		c.mu.Unlock()
+		select {
+		case <-c.dead:
+			return nil, c.deathReason()
+		case <-time.After(100 * time.Millisecond):
+			return nil, err
+		}
+	}
+	timer := time.NewTimer(timeout)
+	defer timer.Stop()
+	select {
+	case m := <-ch:
+		if m.Error != nil {
+			msg := m.Error.Message
+			if msg == "" {
+				msg = "the bundle refused the request"
+			}
+			return nil, errors.New(msg)
+		}
+		return m.Result, nil
+	case <-c.dead:
+		return nil, c.deathReason()
+	case <-timer.C:
+		c.mu.Lock()
+		delete(c.pending, id)
+		c.mu.Unlock()
+		return nil, fmt.Errorf("%s's bundle did not answer %s in %ds", module, method, int(timeout/time.Second))
+	}
+}
+
+func (c *child) deathReason() error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	if c.why != nil {
+		return c.why
+	}
+	return errors.New("the bundle exited")
+}

node-tools/internal/meshtest/meshtest.go

@@ -0,0 +1,184 @@
+// Package meshtest raises what the controller would, for tests against a real bus: the ASSIGNMENTS
+// and EVENTS streams, memberships issued by hand, and a fixture's path.
+//
+// **The packages share one bus, so run them one at a time: `go test -p 1 ./...`.** Each test raises
+// the streams afresh, and the console discovers every runtime that announces itself on the bus
+// (novox/hq ADR 0197) — a runtime from another package's test is, correctly, found.
+package meshtest
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/nats-io/nats.go"
+
+	"github.com/novox/mesh-tools/node-tools/internal/bus"
+)
+
+// URL is the test bus, or the test is skipped.
+func URL(t *testing.T) string {
+	t.Helper()
+	url := os.Getenv("MESH_TEST_NATS")
+	if url == "" {
+		t.Skip("MESH_TEST_NATS unset")
+	}
+	return url
+}
+
+// Mesh is the controller's job, done by hand.
+type Mesh struct {
+	nc *nats.Conn
+	js nats.JetStreamContext
+}
+
+// New raises the streams afresh.
+func New(t *testing.T) *Mesh {
+	t.Helper()
+	nc, err := nats.Connect(URL(t))
+	if err != nil {
+		t.Fatal(err)
+	}
+	js, _ := nc.JetStream()
+	for _, s := range []string{"ASSIGNMENTS", "EVENTS"} {
+		_ = js.DeleteStream(s)
+	}
+	if _, err := js.AddStream(&nats.StreamConfig{Name: "ASSIGNMENTS", Subjects: []string{"mesh.assignment.>"},
+		MaxMsgsPerSubject: 1, AllowDirect: true}); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := js.AddStream(&nats.StreamConfig{Name: "EVENTS", Subjects: []string{"mesh.mod.*.event.>"}}); err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(nc.Close)
+	return &Mesh{nc: nc, js: js}
+}
+
+// Issue publishes a membership.
+func (m *Mesh) Issue(t *testing.T, mem bus.Membership) {
+	t.Helper()
+	body, _ := json.Marshal(mem)
+	if _, err := m.js.Publish(bus.MembershipSubject(mem.Node, mem.Module), body); err != nil {
+		t.Fatal(err)
+	}
+}
+
+// NextEvent is the subject the next event under a pattern lands on.
+func (m *Mesh) NextEvent(t *testing.T, pattern string) <-chan string {
+	t.Helper()
+	ch := make(chan string, 1)
+	sub, err := m.nc.Subscribe(pattern, func(msg *nats.Msg) {
+		select {
+		case ch <- msg.Subject:
+		default:
+		}
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() { _ = sub.Unsubscribe() })
+	_ = m.nc.Flush()
+	return ch
+}
+
+// MembershipOf is a membership as the controller issues one on a machine.
+func MembershipOf(module, node string, plain bool, seats map[string][]string) bus.Membership {
+	own := "mesh.mod." + module
+	serves := []bus.Served{{Subject: own + ".tool.{tool}." + node}}
+	if plain {
+		serves = append(serves, bus.Served{Subject: own + ".tool.{tool}", Queue: "serve." + module})
+	}
+	var verbs []bus.SeatVerb
+	for seat, vs := range seats {
+		for _, v := range vs {
+			verbs = append(verbs, bus.SeatVerb{Seat: seat, Verb: v, Subject: "mesh.seat." + seat + ".tool." + v + "." + node})
+		}
+	}
+	return bus.Membership{Node: node, Module: module, Serves: serves, Seats: verbs,
+		Emits: own + ".event.{event}", Tools: own + ".tool.tools"}
+}
+
+// Fixture is a path in node-tools/test/fixtures, which these tests share with the TypeScript ones.
+func Fixture(name string) string {
+	_, here, _, _ := runtime.Caller(0)
+	return filepath.Join(filepath.Dir(here), "..", "..", "test", "fixtures", name)
+}
+
+// Until retries while the bus answers "no responders" — something not yet served.
+func Until(t *testing.T, try func() error) {
+	t.Helper()
+	var err error
+	for i := 0; i < 50; i++ {
+		if err = try(); err == nil {
+			return
+		}
+		time.Sleep(100 * time.Millisecond)
+	}
+	t.Fatal(err)
+}
+
+// Logs collects what the runtime says.
+type Logs struct{ lines []string }
+
+// Logf is a logger that keeps the lines.
+func (l *Logs) Logf(format string, args ...any) {
+	l.lines = append(l.lines, sprintf(format, args...))
+}
+
+// Has says whether a line contains every fragment.
+func (l *Logs) Has(fragments ...string) bool {
+	for _, line := range l.lines {
+		all := true
+		for _, f := range fragments {
+			all = all && strings.Contains(line, f)
+		}
+		if all {
+			return true
+		}
+	}
+	return false
+}
+
+// All is every line.
+func (l *Logs) All() string { return strings.Join(l.lines, "\n") }
+
+// Consumer makes a module's durable consumer on a machine as the controller does: pull, on the
+// EVENTS stream, filtered to what the module consumes, with a short ack wait so a test sees a
+// redelivery in seconds rather than the mesh's minutes.
+func (m *Mesh) Consumer(t *testing.T, node, module string, filters []string, ackWait time.Duration) {
+	t.Helper()
+	cfg := &nats.ConsumerConfig{Durable: node + "_" + module, AckPolicy: nats.AckExplicitPolicy,
+		AckWait: ackWait, MaxDeliver: 10, DeliverPolicy: nats.DeliverNewPolicy}
+	if len(filters) == 1 {
+		cfg.FilterSubject = filters[0]
+	} else {
+		cfg.FilterSubjects = filters
+	}
+	if _, err := m.js.AddConsumer("EVENTS", cfg); err != nil {
+		t.Fatal(err)
+	}
+}
+
+// Emit publishes an event as a module would, into the EVENTS stream.
+func (m *Mesh) Emit(t *testing.T, subject string, body any) {
+	t.Helper()
+	data, _ := json.Marshal(body)
+	if _, err := m.js.Publish(subject, data); err != nil {
+		t.Fatal(err)
+	}
+}
+
+// Pending is what a module's consumer still holds: delivered and not acknowledged, and not yet
+// delivered.
+func (m *Mesh) Pending(t *testing.T, node, module string) (ackPending, notDelivered uint64) {
+	t.Helper()
+	info, err := m.js.ConsumerInfo("EVENTS", node+"_"+module)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return uint64(info.NumAckPending), info.NumPending
+}

node-tools/internal/meshtest/sprintf.go

@@ -0,0 +1,5 @@
+package meshtest
+
+import "fmt"
+
+func sprintf(format string, args ...any) string { return fmt.Sprintf(format, args...) }

node-tools/internal/runtime/announce_test.go

@@ -0,0 +1,113 @@
+package runtime
+
+import (
+	"encoding/json"
+	"sort"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/nats-io/nats.go"
+	"github.com/nats-io/nats.go/micro"
+
+	"github.com/novox/mesh-tools/node-tools/internal/bus"
+	mt "github.com/novox/mesh-tools/node-tools/internal/meshtest"
+)
+
+// novox/hq ADR 0197: what a runtime serves, it announces — the NATS services protocol's discovery,
+// read here with NATS's own types, each endpoint a subject actually served — and the announcement
+// follows a re-issued membership.
+func TestTheRuntimeAnnouncesWhatItServesInTheServicesProtocol(t *testing.T) {
+	mesh := mt.New(t)
+	mesh.Issue(t, mt.MembershipOf("alpha", "anchor", false, nil))
+	mesh.Issue(t, mt.MembershipOf("beta", "anchor", false, map[string][]string{"node-shelf": {"list", "clear"}}))
+	nodeTools := connect(t, "node-tools", "anchor")
+	stop, err := Run(nodeTools, []Served{
+		{"alpha", []string{mt.Fixture("many-alpha.serve.mjs")}},
+		{"beta", []string{mt.Fixture("many-beta.serve.mjs")}},
+	}, nil, (&mt.Logs{}).Logf)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer stop()
+
+	nc, err := nats.Connect(mt.URL(t))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer nc.Close()
+	info := func() micro.Info {
+		t.Helper()
+		msg, err := nc.Request("$SRV.INFO.node-tools.anchor", nil, 2*time.Second)
+		if err != nil {
+			t.Fatal(err)
+		}
+		var i micro.Info
+		if err := json.Unmarshal(msg.Data, &i); err != nil {
+			t.Fatal(err)
+		}
+		return i
+	}
+	subjects := func(i micro.Info) string {
+		var out []string
+		for _, e := range i.Endpoints {
+			out = append(out, e.Subject+"|"+e.QueueGroup+"|"+e.Metadata["kind"]+"|"+e.Metadata["module"]+"|"+e.Metadata["seat"]+"|"+e.Metadata["scope"]+"|"+e.Metadata["interchangeable"])
+		}
+		sort.Strings(out)
+		return strings.Join(out, "\n")
+	}
+
+	got := info()
+	if got.Type != micro.InfoResponseType || got.Name != "node-tools" || got.ID != "anchor" || got.Version == "" {
+		t.Errorf("identity: %+v", got.ServiceIdentity)
+	}
+	want := strings.Join([]string{
+		"mesh.mod.alpha.tool.one.anchor||tool|alpha|||false",
+		"mesh.mod.alpha.tool.two.anchor||tool|alpha|||false",
+		"mesh.mod.beta.tool.five.anchor||tool|beta|||false",
+		"mesh.mod.beta.tool.four.anchor||tool|beta|||false",
+		"mesh.mod.beta.tool.three.anchor||tool|beta|||false",
+		"mesh.seat.node-shelf.tool.clear.anchor||seat|beta|node-shelf|node|false",
+		"mesh.seat.node-shelf.tool.list.anchor||seat|beta|node-shelf|node|false",
+	}, "\n")
+	if s := subjects(got); s != want {
+		t.Errorf("announced:\n%s\nwant:\n%s", s, want)
+	}
+	for _, e := range got.Endpoints {
+		if e.Metadata["node"] != "anchor" || e.Metadata["description"] == "" || !json.Valid([]byte(e.Metadata["schema"])) {
+			t.Errorf("endpoint metadata: %+v", e)
+		}
+	}
+
+	// Every subject announced is answered.
+	asker := connect(t, "console", "workstation")
+	for _, e := range got.Endpoints {
+		if _, err := asker.Ask("", map[string]any{}, e.Subject); err != nil {
+			t.Errorf("announced %s and does not answer it: %v", e.Subject, err)
+		}
+	}
+
+	// PING answers with the same identity, and a request for another service is not answered.
+	if msg, err := nc.Request("$SRV.PING", nil, 2*time.Second); err != nil || !strings.Contains(string(msg.Data), micro.PingResponseType) {
+		t.Errorf("ping: %v %v", msg, err)
+	}
+	if _, err := nc.Request("$SRV.INFO.somebody-else", nil, 300*time.Millisecond); err == nil {
+		t.Error("answered a request for another service")
+	}
+
+	// alpha is re-issued a plain subject: the announcement says so, and says it is interchangeable.
+	mesh.Issue(t, mt.MembershipOf("alpha", "anchor", true, nil))
+	var after string
+	for i := 0; i < 40; i++ {
+		after = subjects(info())
+		if strings.Contains(after, "mesh.mod.alpha.tool.one|serve.alpha|tool|alpha|||true") {
+			break
+		}
+		time.Sleep(100 * time.Millisecond)
+	}
+	if !strings.Contains(after, "mesh.mod.alpha.tool.one|serve.alpha|tool|alpha|||true") ||
+		!strings.Contains(after, "mesh.mod.alpha.tool.one.anchor||tool|alpha|||true") {
+		t.Errorf("after a re-issued membership:\n%s", after)
+	}
+	_ = bus.Served{}
+}

node-tools/internal/runtime/events_test.go

@@ -0,0 +1,157 @@
+package runtime
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/novox/mesh-tools/node-tools/internal/bus"
+	"github.com/novox/mesh-tools/node-tools/internal/launch"
+	mt "github.com/novox/mesh-tools/node-tools/internal/meshtest"
+)
+
+// A logger safe to write from the runtime's goroutines.
+type lines struct {
+	mu sync.Mutex
+	l  []string
+}
+
+func (s *lines) logf(format string, args ...any) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.l = append(s.l, strings.TrimSpace(sprintf(format, args...)))
+}
+
+func (s *lines) all() string {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return strings.Join(s.l, "\n")
+}
+
+func sprintf(format string, args ...any) string { return fmtSprintf(format, args...) }
+
+func countLines(t *testing.T, path, want string) int {
+	t.Helper()
+	b, _ := os.ReadFile(path)
+	n := 0
+	for _, l := range strings.Split(string(b), "\n") {
+		if l == want {
+			n++
+		}
+	}
+	return n
+}
+
+// novox/hq ADR 0198: a module's long-running code is launched by the node's runtime, and the runtime
+// is its bus — it binds the module's own consumer, hands each event to the bundle, and acknowledges it
+// only when the bundle has taken it; one the bundle failed or died on is offered again.
+func TestTheRuntimeHandsAModulesEventsToItsBundleAndAcknowledgesThemOnlyWhenTaken(t *testing.T) {
+	mesh := mt.New(t)
+	restore := bus.NakDelay
+	bus.NakDelay = 300 * time.Millisecond
+	t.Cleanup(func() { bus.NakDelay = restore })
+	firstPause := launch.RestartFirst
+	launch.RestartFirst = 100 * time.Millisecond
+	t.Cleanup(func() { launch.RestartFirst = firstPause })
+
+	mesh.Issue(t, mt.MembershipOf("watcher", "anchor", false, nil))
+	mesh.Issue(t, mt.MembershipOf("beta", "anchor", true, nil))
+	// The controller's consumer for the module, as its own runtime bound it: anchor_watcher on EVENTS.
+	mesh.Consumer(t, "anchor", "watcher", []string{"mesh.mod.alpha.event.>"}, 2*time.Second)
+
+	nodeTools := connect(t, "node-tools", "anchor")
+	asker := connect(t, "console", "workstation")
+	dir := t.TempDir()
+	log := filepath.Join(dir, "watch.log")
+	said := &lines{}
+	stop, err := Run(nodeTools, []Served{
+		{Module: "watcher", Entrypoints: []string{mt.Fixture("watcher.serve.mjs")}},
+		{Module: "beta", Entrypoints: []string{mt.Fixture("many-beta.serve.mjs")}},
+	}, map[string]map[string]string{"watcher": {"WATCH_LOG": log}}, said.logf)
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(stop)
+	if !strings.Contains(said.all(), "watcher's events arrive on its consumer anchor_watcher") {
+		t.Fatalf("the module's consumer was not bound:\n%s", said.all())
+	}
+
+	// Handled once, acknowledged once.
+	mesh.Emit(t, "mesh.mod.alpha.event.happened", map[string]any{"n": 1})
+	mt.Until(t, func() error {
+		if countLines(t, log, "handled 1") != 1 {
+			return errorf("event 1 not handled yet")
+		}
+		return nil
+	})
+	// The handler fails the first time: not acknowledged, offered again, then handled.
+	mesh.Emit(t, "mesh.mod.alpha.event.happened", map[string]any{"n": 2, "fail": true})
+	// The bundle dies on the first offer: not acknowledged, the bundle is started again and the
+	// event is offered again once its ack wait has passed.
+	mesh.Emit(t, "mesh.mod.alpha.event.happened", map[string]any{"n": 3, "die": true})
+	deadline := time.Now().Add(20 * time.Second)
+	for time.Now().Before(deadline) {
+		if countLines(t, log, "handled 2") == 1 && countLines(t, log, "handled 3") == 1 {
+			break
+		}
+		time.Sleep(200 * time.Millisecond)
+	}
+	if countLines(t, log, "handled 2") != 1 || countLines(t, log, "handled 3") != 1 {
+		b, _ := os.ReadFile(log)
+		t.Fatalf("a failed or interrupted event was not offered again and handled once:\n%s\nruntime:\n%s", b, said.all())
+	}
+	if countLines(t, log, "started") < 2 {
+		t.Errorf("the bundle that died was not started again: %s", said.all())
+	}
+	mt.Until(t, func() error {
+		ack, notYet := mesh.Pending(t, "anchor", "watcher")
+		if ack != 0 || notYet != 0 {
+			return errorf("still pending: %d unacknowledged, %d undelivered", ack, notYet)
+		}
+		return nil
+	})
+	if countLines(t, log, "handled 1") != 1 {
+		t.Errorf("event 1 was handled more than once")
+	}
+
+	// A tool asks another module's tool through the runtime, as the module.
+	got, err := call(t, asker, "watcher.relay@anchor", map[string]any{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	same(t, got, `{"beta":3}`)
+}
+
+// A long-running bundle that exits is started again, without waiting for a call (ADR 0198).
+func TestALongRunningBundleThatExitsIsStartedAgain(t *testing.T) {
+	mesh := mt.New(t)
+	firstPause := launch.RestartFirst
+	launch.RestartFirst = 100 * time.Millisecond
+	t.Cleanup(func() { launch.RestartFirst = firstPause })
+	mesh.Issue(t, mt.MembershipOf("flaky", "anchor", false, nil))
+	nodeTools := connect(t, "node-tools", "anchor")
+	log := filepath.Join(t.TempDir(), "flaky.log")
+	said := &lines{}
+	stop, err := Run(nodeTools, []Served{{Module: "flaky", Entrypoints: []string{mt.Fixture("flaky.serve.mjs")}}},
+		map[string]map[string]string{"flaky": {"FLAKY_LOG": log}}, said.logf)
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(stop)
+	mt.Until(t, func() error {
+		if countLines(t, log, "started") < 3 {
+			return errorf("started %d time(s)", countLines(t, log, "started"))
+		}
+		return nil
+	})
+	if !strings.Contains(said.all(), "flaky's bundle exited (3)") || !strings.Contains(said.all(), "started again in") {
+		t.Errorf("the restart was not said:\n%s", said.all())
+	}
+}
+
+func fmtSprintf(format string, args ...any) string { return fmt.Sprintf(format, args...) }
+func errorf(format string, args ...any) error      { return fmt.Errorf(format, args...) }

node-tools/internal/runtime/runtime.go

@@ -0,0 +1,580 @@
+// Package runtime is the node's tool runtime (novox/hq ADR 0175, ADR 0193), the Go port of
+// node-tools' runtime.ts in its launch-only form: it launches every assigned module's bundle,
+// serves each module's tools on that module's subjects and each held seat's verbs on the seat's,
+// and answers for every module the verb that says what it serves. It imports nothing and knows no
+// language.
+package runtime
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"sync"
+
+	"github.com/novox/mesh-tools/node-tools/internal/announce"
+	"github.com/novox/mesh-tools/node-tools/internal/bus"
+	"github.com/novox/mesh-tools/node-tools/internal/launch"
+)
+
+// ToolsVerb is the verb every module's runtime answers for it (ADR 0152): its tools, from the code
+// that answers them.
+const ToolsVerb = "tools"
+
+// Words the mesh sets for the runtime (ADR 0175, ADR 0192).
+const (
+	ToolModules     = "MESH_TOOL_MODULES"
+	ToolEnv         = "MESH_TOOL_ENV"
+	OperatorAccount = "MESH_OPERATOR_ACCOUNT"
+	OperatorHome    = "MESH_OPERATOR_HOME"
+)
+
+// Served is one module this runtime serves and its entrypoints.
+type Served struct {
+	Module      string
+	Entrypoints []string
+}
+
+// ToolsAnswer is what `tools` answers for one module.
+type ToolsAnswer struct {
+	Module string       `json:"module"`
+	Tools  []ListedTool `json:"tools"`
+	Failed string       `json:"failed,omitempty"`
+}
+
+// ListedTool is one tool as a module's `tools` answer lists it.
+type ListedTool struct {
+	Name        string          `json:"name"`
+	Description string          `json:"description"`
+	Input       json.RawMessage `json:"input"`
+	Subjects    []string        `json:"subjects,omitempty"`
+}
+
+// ServedModulesFrom reads MESH_TOOL_MODULES: `<module>=<entrypoint>` entries, comma-separated, several
+// per module. The one-module form — a bare path, or the runtime's own module — is the per-module
+// containers' (to-be 38 WP4c) and refused here: the node's runtime imports nothing.
+func ServedModulesFrom(spec, own string) ([]Served, error) {
+	order := []string{}
+	by := map[string][]string{}
+	for _, raw := range strings.Split(spec, ",") {
+		entry := strings.TrimSpace(raw)
+		if entry == "" {
+			continue
+		}
+		module, path, ok := strings.Cut(entry, "=")
+		module, path = strings.TrimSpace(module), strings.TrimSpace(path)
+		if !ok || module == "" || path == "" || module == own {
+			return nil, fmt.Errorf("%s: %q is not <module>=<entrypoint> of another module; the node's "+
+				"runtime launches the bundles it is given and imports nothing (novox/hq ADR 0193)", ToolModules, entry)
+		}
+		if _, seen := by[module]; !seen {
+			order = append(order, module)
+		}
+		by[module] = append(by[module], path)
+	}
+	out := make([]Served, 0, len(order))
+	for _, m := range order {
+		out = append(out, Served{Module: m, Entrypoints: by[m]})
+	}
+	return out, nil
+}
+
+// TakeToolEnvs reads the composed environments (ADR 0192) and removes them from the process's, so no
+// bundle finds another's there.
+func TakeToolEnvs() (map[string]map[string]string, error) {
+	raw := os.Getenv(ToolEnv)
+	os.Unsetenv(ToolEnv)
+	out := map[string]map[string]string{}
+	if raw == "" {
+		return out, nil
+	}
+	var parsed map[string]map[string]any
+	if err := json.Unmarshal([]byte(raw), &parsed); err != nil {
+		return nil, fmt.Errorf(`%s is not JSON of the shape {"<module>": {"<word>": "<value>"}}: %w`, ToolEnv, err)
+	}
+	for module, words := range parsed {
+		own := map[string]string{}
+		for k, v := range words {
+			if s, ok := v.(string); ok {
+				own[k] = s
+			} else {
+				b, _ := json.Marshal(v)
+				own[k] = string(b)
+			}
+		}
+		out[module] = own
+	}
+	return out, nil
+}
+
+type registration struct {
+	module string // the module's own name, or a seat's
+	owner  string // the module whose bundle made it
+	tools  []launch.Tool
+}
+
+// Run launches, binds and serves. It answers a stop function.
+func Run(conn *bus.Conn, served []Served, envs map[string]map[string]string, logf func(string, ...any)) (func(), error) {
+	if account := os.Getenv(OperatorAccount); account != "" {
+		home := ""
+		if h := os.Getenv(OperatorHome); h != "" {
+			home = " (home " + h + ")"
+		}
+		logf("[mesh-tools] the operator's account here is %s%s", account, home)
+	}
+	modules := make([]string, 0, len(served))
+	isServed := map[string]bool{}
+	for _, s := range served {
+		modules = append(modules, s.Module)
+		isServed[s.Module] = true
+		conn.Follow(s.Module)
+	}
+	node := conn.Node()
+
+	base := os.Environ()
+	envFor := func(module string) []string {
+		words := map[string]string{}
+		for _, kv := range base {
+			if k, v, ok := strings.Cut(kv, "="); ok && k != ToolEnv {
+				words[k] = v
+			}
+		}
+		for k, v := range envs[module] {
+			words[k] = v
+		}
+		words["MESH_SERVED_MODULE"] = module
+		words["MESH_MODULE"] = module
+		if node != "" {
+			words["MESH_NODE"] = node
+		}
+		out := make([]string, 0, len(words))
+		for k, v := range words {
+			out = append(out, k+"="+v)
+		}
+		sort.Strings(out)
+		return out
+	}
+
+	// The module's events, for every child of it that subscribes (ADR 0198): one consumer per module,
+	// bound the first time any of its children subscribes, each event handed to every child that did.
+	events := &consumers{conn: conn, logf: logf, of: map[string]*moduleEvents{}}
+
+	failed := map[string]string{}
+	var registrations []registration
+	var stops []func()
+	for _, s := range served {
+		for _, entry := range s.Entrypoints {
+			path, _ := filepath.Abs(entry)
+			module := s.Module
+			fail := func(why string) {
+				failed[module] = why
+				logf("[mesh-tools] %s's bundle %s failed to load: %s; its tools are not served here", module, entry, why)
+			}
+			if !launch.Executable(path) {
+				fail(path + " is not executable; a bundle the runtime serves is started, never imported, and its build makes it executable (novox/hq ADR 0193)")
+				continue
+			}
+			child, err := launch.Start(module, path, envFor(module), events.forModule(module), logf)
+			if err != nil {
+				fail(err.Error())
+				continue
+			}
+			stops = append(stops, child.Stop)
+			for _, r := range child.Registrations {
+				registrations = append(registrations, registration{module: r.Module, owner: module, tools: r.Tools})
+			}
+		}
+	}
+
+	claimed := map[string]bool{}
+	for _, m := range modules {
+		if mem := conn.Membership(m); mem != nil {
+			for _, s := range mem.Seats {
+				claimed[s.Seat] = true
+			}
+		}
+	}
+	var own []registration
+	for _, r := range registrations {
+		switch {
+		case isServed[r.module]:
+			own = append(own, r)
+		case claimed[r.module]:
+		default:
+			logf(`[mesh-tools] %s registers tools under "%s", which is neither a module served here nor a seat one of them claims; not served until the mesh issues the claim`, r.owner, r.module)
+		}
+	}
+	stopAll := func() {
+		events.stopAll()
+		for i := len(stops) - 1; i >= 0; i-- {
+			stops[i]()
+		}
+	}
+	for _, r := range own {
+		seen := map[string]bool{}
+		for _, t := range r.tools {
+			if t.Name == ToolsVerb {
+				stopAll()
+				return nil, fmt.Errorf(`%s names a tool "%s", which is the verb the runtime answers for every module with what it serves (novox/hq ADR 0152) — refused, rename it`, r.module, ToolsVerb)
+			}
+			if seen[t.Name] {
+				stopAll()
+				return nil, fmt.Errorf("%s exposes two tools named %s — refused", r.module, t.Name)
+			}
+			seen[t.Name] = true
+		}
+	}
+
+	var names []string
+	byModule := map[string][]launch.Tool{}
+	for _, r := range own {
+		for _, t := range r.tools {
+			t := t
+			stop, err := conn.Handle(r.module+"."+t.Name, func(body json.RawMessage) (any, error) {
+				return t.Run(argsOf(body))
+			})
+			if err != nil {
+				logf("[mesh-tools] cannot serve %s.%s: %v", r.module, t.Name, err)
+				continue
+			}
+			names = append(names, r.module+"."+t.Name)
+			stops = append(stops, stop)
+		}
+		byModule[r.module] = append(byModule[r.module], r.tools...)
+	}
+	for _, module := range modules {
+		module := module
+		tools := byModule[module]
+		why := failed[module]
+		if len(tools) == 0 && why == "" {
+			continue // a pure-events module: silent, as it always was
+		}
+		stop, err := conn.Handle(module+"."+ToolsVerb, func(json.RawMessage) (any, error) {
+			answer := ToolsAnswer{Module: module, Tools: []ListedTool{}, Failed: why}
+			for _, t := range tools {
+				answer.Tools = append(answer.Tools, ListedTool{Name: t.Name, Description: t.Description,
+					Input: t.Input, Subjects: subjectsOf(conn, module, t.Name)})
+			}
+			return answer, nil
+		})
+		if err == nil {
+			stops = append(stops, stop)
+		}
+	}
+
+	failedNames := make([]string, 0, len(failed))
+	for _, m := range modules {
+		if _, f := failed[m]; f {
+			failedNames = append(failedNames, m)
+		}
+	}
+	line := fmt.Sprintf("[mesh-tools] serving %d tool(s) for %d module(s): %s", len(names), len(modules), orNone(names))
+	if len(failedNames) > 0 {
+		line += fmt.Sprintf("; not serving %s, whose bundle(s) failed to load", strings.Join(failedNames, ", "))
+	}
+	logf("%s", line)
+	stops = append(stops, serveSeats(conn, modules, registrations, logf))
+
+	// **What it serves, it announces** (novox/hq ADR 0197): the NATS services protocol's discovery,
+	// answered with what is served at the moment it is asked — re-served memberships included.
+	announced, err := announce.Serve(conn, announce.Service{
+		Name: conn.Module(), ID: instanceOf(conn),
+		Description: "the mesh's tool runtime on " + node + ": every assigned module's tools and the seats they hold",
+		Metadata:    map[string]string{"node": node},
+	}, func() []announce.Endpoint { return endpointsOf(conn, own, registrations, modules) })
+	if err != nil {
+		logf("[mesh-tools] cannot announce what it serves: %v", err)
+	} else {
+		stops = append(stops, announced)
+	}
+	conn.Flush()
+	return stopAll, nil
+}
+
+// instanceOf is this runtime's instance on the bus: its machine, which is what tells two instances of
+// one service apart; the connection's module where it has no machine.
+func instanceOf(conn *bus.Conn) string {
+	if n := conn.Node(); n != "" {
+		return n
+	}
+	return conn.Module()
+}
+
+// endpointsOf is everything this runtime serves now: each served module's tools on every subject the
+// mesh issued for them, and each held seat's verbs on the seat's subject (ADR 0197).
+func endpointsOf(conn *bus.Conn, own []registration, registrations []registration, modules []string) []announce.Endpoint {
+	node := conn.Node()
+	var out []announce.Endpoint
+	for _, r := range own {
+		for _, t := range r.tools {
+			served := conn.ServedOn(r.module, t.Name)
+			interchangeable := false
+			for _, s := range served {
+				interchangeable = interchangeable || s.Subject == "mesh.mod."+r.module+".tool."+t.Name
+			}
+			for _, s := range served {
+				out = append(out, announce.Endpoint{Kind: announce.KindTool, Module: r.module, Tool: t.Name,
+					Node: node, Description: t.Description, Schema: t.Input, Interchangeable: interchangeable,
+					Subject: s.Subject, Queue: s.Queue})
+			}
+		}
+	}
+	impl := map[string]map[string]launch.Tool{}
+	for _, r := range registrations {
+		if impl[r.module] == nil {
+			impl[r.module] = map[string]launch.Tool{}
+		}
+		for _, t := range r.tools {
+			impl[r.module][t.Name] = t
+		}
+	}
+	have := map[string]bool{}
+	for _, module := range modules {
+		m := conn.Membership(module)
+		if m == nil {
+			continue
+		}
+		for _, v := range m.Seats {
+			t, ok := impl[v.Seat][v.Verb]
+			if !ok || have[v.Subject] {
+				continue
+			}
+			have[v.Subject] = true
+			scope := "mesh"
+			if node != "" && strings.HasSuffix(v.Subject, "."+node) {
+				scope = "node"
+			}
+			out = append(out, announce.Endpoint{Kind: announce.KindSeat, Module: module, Tool: v.Verb, Seat: v.Seat,
+				Scope: scope, Node: node, Description: t.Description, Schema: t.Input, Subject: v.Subject})
+		}
+	}
+	return out
+}
+
+func orNone(names []string) string {
+	if len(names) == 0 {
+		return "(none)"
+	}
+	return strings.Join(names, ", ")
+}
+
+// argsOf is a call's arguments as the tool receives them: an object, `{}` for none.
+func argsOf(body json.RawMessage) json.RawMessage {
+	trimmed := strings.TrimSpace(string(body))
+	if trimmed == "" || trimmed == "null" {
+		return json.RawMessage("{}")
+	}
+	return body
+}
+
+// subjectsOf is where a tool is answered as the mesh issued it: the plain subject first, then this
+// machine's; nothing before a membership is issued.
+func subjectsOf(conn *bus.Conn, module, tool string) []string {
+	m := conn.Membership(module)
+	if m == nil {
+		return nil
+	}
+	var plain, mine []string
+	for _, s := range m.Serves {
+		subject := strings.ReplaceAll(s.Subject, "{tool}", tool)
+		if s.Queue != "" {
+			plain = append(plain, subject)
+		} else {
+			mine = append(mine, subject)
+		}
+	}
+	return append(plain, mine...)
+}
+
+// serveSeats serves every verb of every seat a served module holds, where the mesh issued it, by
+// the tool of the same name registered under the seat's name (ADR 0159, 0160) — and serves again
+// whenever a membership changes. Whether this machine holds the seat is the bus's to decide.
+func serveSeats(conn *bus.Conn, modules []string, registrations []registration, logf func(string, ...any)) func() {
+	impl := map[string]map[string]launch.Tool{}
+	for _, r := range registrations {
+		if impl[r.module] == nil {
+			impl[r.module] = map[string]launch.Tool{}
+		}
+		for _, t := range r.tools {
+			impl[r.module][t.Name] = t
+		}
+	}
+	var mu sync.Mutex
+	var stops []func()
+	serve := func() {
+		mu.Lock()
+		defer mu.Unlock()
+		for _, s := range stops {
+			s()
+		}
+		stops = nil
+		have := map[string]bool{}
+		for _, module := range modules {
+			m := conn.Membership(module)
+			if m == nil {
+				continue
+			}
+			for _, v := range m.Seats {
+				if have[v.Subject] {
+					continue
+				}
+				have[v.Subject] = true
+				t, ok := impl[v.Seat][v.Verb]
+				if !ok {
+					logf("[mesh-tools] %s claims %s and implements no %s, which that seat promises; not served", module, v.Seat, v.Verb)
+					continue
+				}
+				stop, err := conn.HandleSubject(v.Subject, func(body json.RawMessage) (any, error) {
+					return t.Run(argsOf(body))
+				})
+				if err != nil {
+					logf("[mesh-tools] cannot serve %s's %s on %s: %v", v.Seat, v.Verb, v.Subject, err)
+					continue
+				}
+				stops = append(stops, stop)
+				logf("[mesh-tools] serving %s's %s on %s, admitted where %s holds the seat", v.Seat, v.Verb, v.Subject, module)
+			}
+		}
+	}
+	serve()
+	conn.OnMembership(func(bus.Membership) { go func() { serve(); conn.Flush() }() })
+	return func() {
+		mu.Lock()
+		defer mu.Unlock()
+		for _, s := range stops {
+			s()
+		}
+		stops = nil
+	}
+}
+
+// consumers holds, per module the runtime serves, the one durable consumer its events arrive on and
+// the children its events are handed to (novox/hq ADR 0198).
+type consumers struct {
+	conn *bus.Conn
+	logf func(string, ...any)
+	mu   sync.Mutex
+	of   map[string]*moduleEvents
+}
+
+type moduleEvents struct {
+	stop     func()
+	delivers []*func(json.RawMessage) error
+}
+
+// stopAll unbinds every module's consumer.
+func (c *consumers) stopAll() {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	for _, m := range c.of {
+		if m.stop != nil {
+			m.stop()
+		}
+	}
+	c.of = map[string]*moduleEvents{}
+}
+
+// forModule is the bus one launched bundle of a module reaches the mesh through.
+func (c *consumers) forModule(module string) launch.Bus {
+	return &moduleBus{all: c, module: module}
+}
+
+type moduleBus struct {
+	all     *consumers
+	module  string
+	mu      sync.Mutex
+	deliver *func(json.RawMessage) error
+}
+
+// Publish emits an event as the module (ADR 0193).
+func (b *moduleBus) Publish(params json.RawMessage) error {
+	var env bus.Envelope
+	if err := json.Unmarshal(params, &env); err != nil {
+		return fmt.Errorf("not an event envelope: %w", err)
+	}
+	return b.all.conn.PublishAs(b.module, env)
+}
+
+// Ask calls a tool as the module: `{key, body}`, answered with the tool's result (ADR 0198).
+func (b *moduleBus) Ask(params json.RawMessage) (json.RawMessage, error) {
+	var asked struct {
+		Key  string          `json:"key"`
+		Body json.RawMessage `json:"body"`
+	}
+	if err := json.Unmarshal(params, &asked); err != nil || asked.Key == "" {
+		return nil, fmt.Errorf("mesh/ask names no tool: {key, body}")
+	}
+	body := any(asked.Body)
+	if len(asked.Body) == 0 {
+		body = map[string]any{}
+	}
+	answered, err := b.all.conn.AskAs(b.module, asked.Key, body)
+	if err != nil {
+		return nil, err
+	}
+	if len(answered.Result) == 0 {
+		return json.RawMessage("null"), nil
+	}
+	return answered.Result, nil
+}
+
+// Subscribe hands this bundle the module's events. The consumer is bound once per module; each of
+// the module's children that subscribed is handed every event, and the event is acknowledged only
+// when all of them took it — one consumer split between two readers would give each half.
+func (b *moduleBus) Subscribe(deliver func(json.RawMessage) error) error {
+	b.mu.Lock()
+	if b.deliver == nil {
+		d := deliver
+		b.deliver = &d
+	} else {
+		*b.deliver = deliver
+	}
+	mine := b.deliver
+	b.mu.Unlock()
+
+	c := b.all
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	m := c.of[b.module]
+	if m == nil {
+		m = &moduleEvents{}
+		c.of[b.module] = m
+	}
+	listed := false
+	for _, d := range m.delivers {
+		if d == mine {
+			listed = true
+		}
+	}
+	if !listed {
+		m.delivers = append(m.delivers, mine)
+	}
+	if m.stop != nil {
+		return nil
+	}
+	module := b.module
+	stop, err := c.conn.ConsumeAs(module, func(env bus.Envelope) error {
+		raw, err := json.Marshal(env)
+		if err != nil {
+			return err
+		}
+		c.mu.Lock()
+		targets := append([]*func(json.RawMessage) error(nil), c.of[module].delivers...)
+		c.mu.Unlock()
+		for _, d := range targets {
+			if err := (*d)(raw); err != nil {
+				c.logf("[mesh-tools] %s did not take %s: %v; offered again", module, env.Key, err)
+				return err
+			}
+		}
+		return nil
+	})
+	if err != nil {
+		return err
+	}
+	m.stop = stop
+	c.logf("[mesh-tools] %s's events arrive on its consumer %s", module, bus.ConsumerOf(c.conn.Node(), module))
+	return nil
+}

node-tools/internal/runtime/runtime_test.go

@@ -0,0 +1,251 @@
+package runtime
+
+import (
+	"encoding/json"
+	"os"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/novox/mesh-tools/node-tools/internal/bus"
+	mt "github.com/novox/mesh-tools/node-tools/internal/meshtest"
+)
+
+func connect(t *testing.T, module, node string) *bus.Conn {
+	t.Helper()
+	c, err := bus.Connect(bus.Credential{URL: mt.URL(t), Module: module, Node: node})
+	if err != nil {
+		t.Fatal(err)
+	}
+	c.Logf = func(string, ...any) {}
+	t.Cleanup(c.Close)
+	return c
+}
+
+func call(t *testing.T, asker *bus.Conn, key string, args any) (string, error) {
+	t.Helper()
+	got, err := asker.Ask(key, args, "")
+	return string(got.Result), err
+}
+
+func same(t *testing.T, got, want string) {
+	t.Helper()
+	var a, b any
+	if json.Unmarshal([]byte(got), &a) != nil || json.Unmarshal([]byte(want), &b) != nil {
+		t.Fatalf("not JSON: got %s want %s", got, want)
+	}
+	ga, _ := json.Marshal(a)
+	gb, _ := json.Marshal(b)
+	if string(ga) != string(gb) {
+		t.Errorf("got %s, want %s", got, want)
+	}
+}
+
+// The node's runtime serves five modules' bundles on one credential — two TypeScript, one broken,
+// one Python, one written against the protocol — and follows a re-issued membership (ADR 0175, 0193).
+func TestTheNodesRuntimeServesFiveModulesAndFollowsAReissuedMembership(t *testing.T) {
+	mesh := mt.New(t)
+	mesh.Issue(t, mt.MembershipOf("alpha", "anchor", true, nil))
+	mesh.Issue(t, mt.MembershipOf("beta", "anchor", false, map[string][]string{"node-shelf": {"list", "clear"}}))
+	mesh.Issue(t, mt.MembershipOf("gamma", "anchor", false, nil))
+	mesh.Issue(t, mt.MembershipOf("delta", "anchor", false, map[string][]string{"node-lamp": {"on"}}))
+	mesh.Issue(t, mt.MembershipOf("epsilon", "anchor", false, nil))
+	nodeTools := connect(t, "node-tools", "anchor")
+	asker := connect(t, "console", "workstation")
+	logs := &mt.Logs{}
+	t.Setenv("MESH_OPERATOR_ACCOUNT", "somebody")
+	t.Setenv("MESH_OPERATOR_HOME", "/home/somebody")
+	stop, err := Run(nodeTools, []Served{
+		{"alpha", []string{mt.Fixture("many-alpha.serve.mjs")}},
+		{"beta", []string{mt.Fixture("many-beta.serve.mjs")}},
+		{"gamma", []string{mt.Fixture("many-broken.serve.mjs")}},
+		{"delta", []string{mt.Fixture("many-delta.py")}},
+		{"epsilon", []string{mt.Fixture("many-epsilon.mjs")}},
+	}, nil, logs.Logf)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer stop()
+	if !logs.Has("the operator's account here is somebody (home /home/somebody)") {
+		t.Errorf("the operator was not said:\n%s", logs.All())
+	}
+	if !logs.Has("gamma's bundle", "many-broken.serve.mjs failed to load: gamma's bundle exited (1): Error: gamma's bundle cannot find its client; its tools are not served here") {
+		t.Errorf("the broken bundle was not named with its own words:\n%s", logs.All())
+	}
+	if !logs.Has("serving 8 tool(s) for 5 module(s): alpha.one, alpha.two, beta.three, beta.four, beta.five, delta.greet, delta.die, epsilon.seven; not serving gamma") {
+		t.Errorf("not serving what it should:\n%s", logs.All())
+	}
+
+	for key, want := range map[string]string{
+		"alpha.one": `{"alpha":1}`, "alpha.one@anchor": `{"alpha":1}`, "beta.three@anchor": `{"beta":3}`,
+		"beta.four@anchor": `{"beta":4}`, "beta.five@anchor": `{"beta":5}`,
+		"seat:node-shelf.list@anchor": `{"shelf":["a","b"]}`, "seat:node-shelf.clear@anchor": `{"cleared":true}`,
+		"seat:node-lamp.on@anchor": `{"on":true,"language":"python"}`, "epsilon.seven@anchor": `{"epsilon":7,"via":"stdio"}`,
+	} {
+		got, err := call(t, asker, key, map[string]any{})
+		if err != nil {
+			t.Errorf("%s: %v", key, err)
+			continue
+		}
+		same(t, got, want)
+	}
+	if _, err := call(t, asker, "beta.three", map[string]any{}); err == nil || !strings.Contains(err.Error(), "no responders") {
+		t.Errorf("beta was not issued the plain subject, and answered on it: %v", err)
+	}
+	got, err := call(t, asker, "delta.greet@anchor", map[string]any{"who": "mesh"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	same(t, got, `{"greeting":"hello mesh","language":"python"}`)
+
+	// A launched tool that emits does so as its module, through the runtime.
+	landed := mesh.NextEvent(t, "mesh.mod.*.event.>")
+	got, err = call(t, asker, "alpha.two", map[string]any{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	same(t, got, `{"alpha":2}`)
+	select {
+	case subject := <-landed:
+		if subject != "mesh.mod.alpha.event.happened" {
+			t.Errorf("the event landed on %s", subject)
+		}
+	case <-time.After(5 * time.Second):
+		t.Error("the event never landed")
+	}
+
+	// A bundle that dies mid-call is said, and started again on its next call.
+	if _, err := call(t, asker, "delta.die@anchor", map[string]any{}); err == nil {
+		t.Error("a bundle that died answered")
+	}
+	got, err = call(t, asker, "delta.greet@anchor", map[string]any{"who": "again"})
+	if err != nil {
+		t.Fatalf("not started again: %v", err)
+	}
+	same(t, got, `{"greeting":"hello again","language":"python"}`)
+
+	// `tools` answers for each, and why gamma serves nothing.
+	gamma, err := call(t, asker, "gamma.tools@anchor", map[string]any{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	same(t, gamma, `{"module":"gamma","tools":[],"failed":"gamma's bundle exited (1): Error: gamma's bundle cannot find its client"}`)
+	beta, _ := call(t, asker, "beta.tools@anchor", map[string]any{})
+	var answer ToolsAnswer
+	_ = json.Unmarshal([]byte(beta), &answer)
+	if len(answer.Tools) != 3 || answer.Tools[0].Name != "three" || strings.Join(answer.Tools[0].Subjects, ",") != "mesh.mod.beta.tool.three.anchor" {
+		t.Errorf("beta's tools answer: %s", beta)
+	}
+
+	// Re-issued mid-run, now answering for the module anywhere: served without a restart.
+	mesh.Issue(t, mt.MembershipOf("beta", "anchor", true, map[string][]string{"node-shelf": {"list", "clear"}}))
+	mt.Until(t, func() error { _, err := call(t, asker, "beta.three", map[string]any{}); return err })
+	got, err = call(t, asker, "seat:node-shelf.list@anchor", map[string]any{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	same(t, got, `{"shelf":["a","b"]}`)
+}
+
+// Each bundle is given its own environment and none of another's (ADR 0192), and the composed
+// environments are not left in the runtime's.
+func TestEachBundleIsGivenItsOwnEnvironment(t *testing.T) {
+	mesh := mt.New(t)
+	for _, m := range []string{"gamma", "delta", "zeta"} {
+		mesh.Issue(t, mt.MembershipOf(m, "anchor", false, nil))
+	}
+	nodeTools := connect(t, "node-tools", "anchor")
+	asker := connect(t, "console", "workstation")
+	t.Setenv("MESH_OPERATOR_ACCOUNT", "somebody")
+	t.Setenv(ToolEnv, `{"gamma":{"GAMMA_CONFIG_FILE":"/var/lib/mesh/gamma/config.json"},"delta":{"DELTA_TOKEN_FILE":"/var/lib/mesh/delta/token"},"zeta":{"ZETA_URL":"http://127.0.0.1:3000"}}`)
+	envs, err := TakeToolEnvs()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, left := os.LookupEnv(ToolEnv); left {
+		t.Error("the composed environments were left in the runtime's")
+	}
+	logs := &mt.Logs{}
+	stop, err := Run(nodeTools, []Served{
+		{"gamma", []string{mt.Fixture("env-gamma.serve.mjs")}},
+		{"delta", []string{mt.Fixture("env-delta.serve.mjs")}},
+		{"zeta", []string{mt.Fixture("env-zeta.mjs")}},
+	}, envs, logs.Logf)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer stop()
+	for key, want := range map[string]string{
+		"gamma.given@anchor": `{"mine":"/var/lib/mesh/gamma/config.json","theirs":null,"runtime":"somebody","composed":null}`,
+		"delta.given@anchor": `{"mine":"/var/lib/mesh/delta/token","theirs":null}`,
+		"zeta.given@anchor":  `{"mine":"http://127.0.0.1:3000","theirs":null,"composed":null}`,
+	} {
+		got, err := call(t, asker, key, map[string]any{})
+		if err != nil {
+			t.Fatalf("%s: %v\n%s", key, err, logs.All())
+		}
+		same(t, got, want)
+	}
+}
+
+// An entrypoint that is not executable is refused by name, and the others serve (ADR 0193).
+func TestAnEntrypointThatIsNotExecutableIsRefused(t *testing.T) {
+	mesh := mt.New(t)
+	mesh.Issue(t, mt.MembershipOf("alpha", "anchor", false, nil))
+	mesh.Issue(t, mt.MembershipOf("plain", "anchor", false, nil))
+	nodeTools := connect(t, "node-tools", "anchor")
+	asker := connect(t, "console", "workstation")
+	logs := &mt.Logs{}
+	stop, err := Run(nodeTools, []Served{
+		{"alpha", []string{mt.Fixture("many-alpha.serve.mjs")}},
+		{"plain", []string{mt.Fixture("many-alpha.mjs")}},
+	}, nil, logs.Logf)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer stop()
+	if !logs.Has("plain's bundle", "many-alpha.mjs failed to load:", "is not executable; a bundle the runtime serves is started, never imported") {
+		t.Errorf("the non-executable entrypoint was not refused by name:\n%s", logs.All())
+	}
+	got, err := call(t, asker, "alpha.one@anchor", map[string]any{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	same(t, got, `{"alpha":1}`)
+}
+
+// A launched bundle is told the module it serves, so its seat's verbs stay the seat's (ADR 0193).
+func TestALaunchedBundleRegisteringItsSeatFirstServesTheSeat(t *testing.T) {
+	mesh := mt.New(t)
+	mesh.Issue(t, mt.MembershipOf("theta", "anchor", false, map[string][]string{"node-shelf": {"list"}}))
+	nodeTools := connect(t, "node-tools", "anchor")
+	asker := connect(t, "console", "workstation")
+	stop, err := Run(nodeTools, []Served{{"theta", []string{mt.Fixture("served-seat-first.mjs")}}},
+		map[string]map[string]string{"theta": {"THETA_WORD": "given"}}, (&mt.Logs{}).Logf)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer stop()
+	got, err := call(t, asker, "theta.own@anchor", map[string]any{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	same(t, got, `{"theta":"given"}`)
+	got, err = call(t, asker, "seat:node-shelf.list@anchor", map[string]any{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	same(t, got, `{"shelf":["x"]}`)
+}
+
+func TestToolModulesNamesOtherModulesOnly(t *testing.T) {
+	got, err := ServedModulesFrom(" alpha=/a/tools/index.serve.mjs, beta=/b/one, beta=/b/two ", "node-tools")
+	if err != nil || len(got) != 2 || got[1].Module != "beta" || len(got[1].Entrypoints) != 2 {
+		t.Fatalf("%v %v", got, err)
+	}
+	for _, bad := range []string{"/mine/index.js", "node-tools=/own.js", "=/x"} {
+		if _, err := ServedModulesFrom(bad, "node-tools"); err == nil {
+			t.Errorf("%q was accepted", bad)
+		}
+	}
+}

node-tools/internal/wire/wire.go

@@ -0,0 +1,18 @@
+// Package wire is JSON as the TypeScript runtime writes it: no HTML escaping of <, > and &.
+package wire
+
+import (
+	"bytes"
+	"encoding/json"
+)
+
+// Marshal encodes v the way JSON.stringify does, without a trailing newline.
+func Marshal(v any) ([]byte, error) {
+	var b bytes.Buffer
+	enc := json.NewEncoder(&b)
+	enc.SetEscapeHTML(false)
+	if err := enc.Encode(v); err != nil {
+		return nil, err
+	}
+	return bytes.TrimRight(b.Bytes(), "\n"), nil
+}

node-tools/module.json

@@ -35,10 +35,10 @@
       {
         "name": "runtime",
         "kind": "bundle",
-        "language": "typescript",
-        "entrypoints": [
-          "src/main.js"
-        ]
+        "language": "go",
+        "system": "arch",
+        "from": "cmd/node-tools",
+        "binary": "node-tools"
       }
     ]
   }

node-tools/package.json

@@ -13,11 +13,12 @@
     "test": "node --test --test-concurrency=1 --experimental-strip-types 'test/*.test.ts'"
   },
   "dependencies": {
-    "@novox/mesh-sdk": "^0.1.0",
+    "@novox/mesh-sdk": "^0.1.6",
     "nats": "^2.29.0"
   },
   "devDependencies": {
     "@types/node": "^22.20.1",
-    "typescript": "^5.9.3"
+    "typescript": "^5.9.3",
+    "esbuild": "^0.25.0"
   }
 }

node-tools/src/announce.ts

@@ -0,0 +1,139 @@
+// What a runtime serves, it announces (novox/hq ADR 0197): the NATS services protocol's discovery —
+// `$SRV.PING`, `$SRV.INFO`, `$SRV.STATS`, and the same followed by the service's name and its id —
+// answered in the io.nats.micro.v1 format with what is served at the moment of the request. Serving is
+// unchanged; this only says what is served. One service per runtime process, because the bus admits
+// one reply per request from each responder: one endpoint per tool per subject, its metadata saying
+// which module, seat, scope and machine it is. The same shape the Go runtime answers.
+
+import { StringCodec } from "nats";
+import { asSchema } from "@novox/mesh-sdk/stdio";
+import type { ToolDefinition } from "@novox/mesh-sdk/tools";
+import type { RuntimeBroker } from "./broker-nats.js";
+
+const sc = StringCodec();
+
+export const VERSION = "0.1.0";
+export const INFO_RESPONSE = "io.nats.micro.v1.info_response";
+export const PING_RESPONSE = "io.nats.micro.v1.ping_response";
+export const STATS_RESPONSE = "io.nats.micro.v1.stats_response";
+
+/** One tool served on one subject, as announced. */
+export interface Endpoint {
+  kind: "tool" | "seat";
+  module: string;
+  tool: string;
+  seat?: string;
+  scope?: "mesh" | "node";
+  node: string;
+  description: string;
+  schema: unknown;
+  interchangeable: boolean;
+  subject: string;
+  queue?: string;
+}
+
+/** A seat's verb as the runtime serves it, with the definition that answers it. */
+export interface ServedSeatVerb {
+  seat: string;
+  verb: string;
+  subject: string;
+  holder: string;
+  tool: ToolDefinition;
+}
+
+export interface Service {
+  name: string;
+  id: string;
+  description: string;
+  metadata: Record<string, string>;
+}
+
+/** The endpoint's name as the protocol allows it; the metadata, not the name, identifies it. */
+function nameOf(e: Endpoint): string {
+  const clean = (s: string) => s.replace(/[^A-Za-z0-9_-]/g, "_");
+  return `${clean(e.kind === "seat" ? e.seat ?? "" : e.module)}__${clean(e.tool)}`;
+}
+
+/** The info_response for these endpoints. */
+export function info(s: Service, endpoints: Endpoint[]): Record<string, unknown> {
+  return {
+    name: s.name, id: s.id, version: VERSION, metadata: s.metadata, type: INFO_RESPONSE, description: s.description,
+    endpoints: endpoints.map((e) => {
+      const metadata: Record<string, string> = {
+        kind: e.kind, module: e.module, tool: e.tool, node: e.node, description: e.description,
+        schema: JSON.stringify(e.schema ?? {}), interchangeable: e.interchangeable ? "true" : "false",
+      };
+      if (e.kind === "seat") {
+        metadata.seat = e.seat ?? "";
+        metadata.scope = e.scope ?? "mesh";
+      }
+      return { name: nameOf(e), subject: e.subject, queue_group: e.queue ?? "", metadata };
+    }),
+  };
+}
+
+/** Everything served now: each module's tools on every subject issued for them, and each held
+ *  seat's verbs on the seat's subject. */
+export function endpointsOf(
+  broker: RuntimeBroker,
+  own: { module: string; tools: ToolDefinition[] }[],
+  seats: ServedSeatVerb[],
+): Endpoint[] {
+  const node = broker.node ?? "";
+  const out: Endpoint[] = [];
+  for (const { module, tools } of own) {
+    for (const t of tools) {
+      const served = broker.servedOn ? broker.servedOn(module, t.name) : [];
+      const interchangeable = served.some((s) => s.subject === `mesh.mod.${module}.tool.${t.name}`);
+      for (const s of served) {
+        out.push({ kind: "tool", module, tool: t.name, node, description: t.description, schema: asSchema(t.input),
+          interchangeable, subject: s.subject, queue: s.queue });
+      }
+    }
+  }
+  for (const v of seats) {
+    out.push({ kind: "seat", module: v.holder, tool: v.verb, seat: v.seat,
+      scope: node && v.subject.endsWith(`.${node}`) ? "node" : "mesh", node, description: v.tool.description,
+      schema: asSchema(v.tool.input), interchangeable: false, subject: v.subject });
+  }
+  return out;
+}
+
+/** Answer discovery for one service until stopped. */
+export function announce(broker: RuntimeBroker, s: Service, current: () => Endpoint[]): () => void {
+  const started = new Date().toISOString();
+  const identity = { name: s.name, id: s.id, version: VERSION, metadata: s.metadata };
+  const answer = (subject: string): Uint8Array | undefined => {
+    const parts = subject.split(".");
+    if (parts[0] !== "$SRV" || parts.length < 2) return undefined;
+    if (parts.length >= 3 && parts[2] !== s.name) return undefined; // another service's
+    if (parts.length >= 4 && parts[3] !== s.id) return undefined; // another instance's
+    let v: unknown;
+    switch (parts[1]) {
+      case "PING":
+        v = { ...identity, type: PING_RESPONSE };
+        break;
+      case "INFO":
+        v = info(s, current());
+        break;
+      case "STATS":
+        v = { ...identity, type: STATS_RESPONSE, started, endpoints: current().map((e) => ({
+          name: nameOf(e), subject: e.subject, queue_group: e.queue ?? "", num_requests: 0, num_errors: 0,
+          last_error: "", processing_time: 0, average_processing_time: 0 })) };
+        break;
+      default:
+        return undefined;
+    }
+    return sc.encode(JSON.stringify(v));
+  };
+  const stops: (() => void)[] = [];
+  // Exactly the questions asked of every service and of this one by name and instance — what the
+  // grants allow (novox/hq ADR 0197). A wildcard is refused by the bus, and a refused subscription
+  // ends a runtime: on 2026-10-03 it crash-looped every container that announced itself.
+  for (const verb of ["PING", "INFO", "STATS"]) {
+    for (const subject of [`$SRV.${verb}`, `$SRV.${verb}.${s.name}`, `$SRV.${verb}.${s.name}.${s.id}`]) {
+      stops.push(broker.raw!(subject, (subj) => answer(subj)));
+    }
+  }
+  return () => stops.forEach((stop) => stop());
+}

node-tools/src/broker-nats.ts

@@ -97,6 +97,13 @@ export interface RuntimeBroker extends Broker {
   serving(): string[];
   /** The module this connection is: what its credential named, and what a bare key serves as. */
   readonly module: string;
+  /** Where a served module's tool is answered right now (ADR 0197: what it serves, it announces). */
+  servedOn?(module: string, tool: string): { subject: string; queue?: string }[];
+  /** Answer a subject in a format of its own, not a tool's reply envelope — the NATS services
+   *  protocol's discovery (novox/hq ADR 0197). An undefined answer is no reply. */
+  raw?(subject: string, answer: (subject: string, data: Uint8Array) => Uint8Array | undefined): () => void;
+  /** The machine this connection serves on, when its credential names one. */
+  readonly node?: string;
 }
 
 /**
@@ -270,17 +277,27 @@ export async function connectNats(
     const sub = conn.subscribe(subject, queue ? { queue } : {});
     subs.push(sub);
     void (async () => {
-      for await (const msg of sub) {
-        let reply: { result?: Res; error?: string; node?: string };
-        try {
-          reply = { result: await handler(JSON.parse(sc.decode(msg.data)) as Req) };
-        } catch (err) {
-          // The caller is told, rather than left to time out: a handler that threw is a
-          // different failure from a tool nobody serves, and only one of them is worth retrying.
-          reply = { error: err instanceof Error ? err.message : String(err) };
+      // **A refused subscription is said, never fatal** (novox/hq 04-ISSUES/218, as 217 for the
+      // announcements). The grants are the mesh's word on what this account may answer; a subject
+      // they leave out — a seat claimed here and held elsewhere — costs that subject, never the
+      // module's other tools, its handlers and its provisioning. Unhandled, the refusal ended the
+      // process and a module's runtime crash-looped on 2026-10-04.
+      try {
+        for await (const msg of sub) {
+          let reply: { result?: Res; error?: string; node?: string };
+          try {
+            reply = { result: await handler(JSON.parse(sc.decode(msg.data)) as Req) };
+          } catch (err) {
+            // The caller is told, rather than left to time out: a handler that threw is a
+            // different failure from a tool nobody serves, and only one of them is worth retrying.
+            reply = { error: err instanceof Error ? err.message : String(err) };
+          }
+          if (node) reply.node = node;
+          msg.respond(sc.encode(JSON.stringify(reply)));
         }
-        if (node) reply.node = node;
-        msg.respond(sc.encode(JSON.stringify(reply)));
+      } catch (err) {
+        console.log(`[mesh-tools] the bus refused ${subject}: ${err instanceof Error ? err.message : String(err)}; ` +
+          "not served here, and the rest serves on");
       }
     })();
     return () => sub.unsubscribe();
@@ -348,6 +365,28 @@ export async function connectNats(
     },
 
     module: self,
+    node,
+    servedOn,
+    raw(subject: string, answer: (subject: string, data: Uint8Array) => Uint8Array | undefined): () => void {
+      const sub = conn.subscribe(subject);
+      subs.push(sub);
+      void (async () => {
+        // **A refusal here is said, never fatal** (novox/hq 04-ISSUES/217). This serves discovery —
+        // what the runtime says about itself — not the work; a bus that refuses it costs the mesh
+        // seeing this runtime, not the runtime's tools and handlers. Unhandled, the refusal ended the
+        // process and every per-module container crash-looped on 2026-10-03.
+        try {
+          for await (const msg of sub) {
+            const body = answer(msg.subject, msg.data);
+            if (body) msg.respond(body);
+          }
+        } catch (err) {
+          console.log(`[mesh-tools] the bus refused ${subject}: ${err instanceof Error ? err.message : String(err)}; ` +
+            "discovery will not see this runtime there, and it serves on");
+        }
+      })();
+      return () => sub.unsubscribe();
+    },
     follow,
     serving: () => [...issued.keys()],
     membership: (module?: string) => issued.get(module ?? self),

node-tools/src/launch.ts

@@ -13,6 +13,8 @@
 import { spawn, type ChildProcess } from "node:child_process";
 import { accessSync, constants } from "node:fs";
 import type { ToolDefinition } from "@novox/mesh-sdk/tools";
+import { broker, type Envelope } from "@novox/mesh-sdk/messaging";
+import { atWork } from "./broker-nats.js";
 
 /** The protocol version this speaks; a bundle says the same. */
 export const PROTOCOL = "2025-03-26";
@@ -71,29 +73,50 @@ export async function launch(module: string, entry: string, env: NodeJS.ProcessE
         const line = buffered.slice(0, at).trim();
         buffered = buffered.slice(at + 1);
         if (!line) continue;
-        let reply: { id?: number; result?: unknown; error?: { message?: string } };
+        let reply: { id?: number | string; method?: string; params?: unknown; result?: unknown; error?: { message?: string } };
         try {
           reply = JSON.parse(line);
         } catch {
           console.log(`[mesh-tools] ${module}'s bundle said something that is not a reply: ${line.slice(0, 120)}`);
           continue;
         }
+        // **The bundle asks the runtime to emit** (novox/hq ADR 0193): published on the bus as this
+        // module, and answered once the bus has accepted it, so the tool's emit means what it means
+        // in-process. Nothing else a bundle may ask.
+        if (typeof reply.method === "string") {
+          const id = reply.id;
+          const answer = (m: Record<string, unknown>) => proc.stdin!.write(JSON.stringify({ jsonrpc: "2.0", id, ...m }) + "\n");
+          if (reply.method !== "mesh/publish") {
+            if (id !== undefined) answer({ error: { code: -32601, message: `the runtime answers no ${reply.method} from a bundle` } });
+            continue;
+          }
+          atWork.run({ module }, () => broker().publish(reply.params as Envelope<unknown>))
+            .then(() => { if (id !== undefined) answer({ result: {} }); })
+            .catch((err: unknown) => { if (id !== undefined) answer({ error: { code: -32000, message: err instanceof Error ? err.message : String(err) } }); });
+          continue;
+        }
         const waiting = typeof reply.id === "number" ? pending.get(reply.id) : undefined;
         if (!waiting) continue;
-        pending.delete(reply.id!);
+        pending.delete(reply.id as number);
         clearTimeout(waiting.timer);
         if (reply.error) waiting.reject(new Error(reply.error.message ?? "the bundle refused the request"));
         else waiting.resolve(reply.result);
       }
     });
     // stderr is the bundle's log; kept under the module's name so a fault reads where it belongs.
+    // The last thing it said is kept, so a bundle that dies says why in its own words, not by code.
+    let lastSaid = "";
     proc.stderr!.on("data", (chunk: Buffer) => {
-      for (const line of chunk.toString("utf8").split("\n")) if (line.trim()) console.log(`[${module}] ${line}`);
+      for (const line of chunk.toString("utf8").split("\n")) {
+        if (!line.trim()) continue;
+        console.log(`[${module}] ${line}`);
+        if (/\S/.test(line) && !/^\s+at\s/.test(line) && !/^Node\.js v/.test(line)) lastSaid = line.trim();
+      }
     });
     const exited = new Promise<never>((_, reject) => {
       proc.once("error", (err) => reject(err));
       proc.once("exit", (code, signal) => {
-        const why = `${module}'s bundle exited (${signal ?? code})`;
+        const why = `${module}'s bundle exited (${signal ?? code})` + (lastSaid ? `: ${lastSaid}` : "");
         for (const [id, p] of pending) {
           pending.delete(id);
           clearTimeout(p.timer);

node-tools/src/main.ts

@@ -29,7 +29,7 @@
 import { readFileSync } from "node:fs";
 import { pathToFileURL } from "node:url";
 import { connectNats, fatalBrokerReason as fatalNatsReason, type Credential } from "./broker-nats.js";
-import { runTools, type ServedModule } from "./runtime.js";
+import { takeToolEnvs, runTools, type ServedModule } from "./runtime.js";
 import { serveMcpHttp, type Listening } from "./http.js";
 
 /** The credential this process connected with, for what it says beyond the connection (ADR 0159). */
@@ -163,7 +163,9 @@ async function serve(): Promise<void> {
   const broker = await connectBrokerPatiently();
   // Parsed after connecting: a bare entrypoint belongs to the module the credential names.
   const { serves, moduleEntrypoints } = servedModulesFrom(process.env.MESH_TOOL_MODULES ?? "", lastCredential?.module);
-  const stop = await runTools({ broker, serves, moduleEntrypoints, credential: lastCredential });
+  // Each module's environment, composed by the mesh (ADR 0192): taken before any bundle is imported.
+  const envs = takeToolEnvs();
+  const stop = await runTools({ broker, serves, moduleEntrypoints, credential: lastCredential, envs });
 
   // The console is this runtime's serving mode (ADR 0175 §6): as node-tools, or wherever the
   // listen address is given, the same process answers MCP on loopback for whoever is on the

node-tools/src/runtime.ts

@@ -9,15 +9,14 @@
 // and the per-module shape is the list with one entry. A bundle that fails to import is named —
 // in the log and in what `tools` answers for it — and the others serve.
 
-import { fileURLToPath, pathToFileURL } from "node:url";
-import { dirname, join, resolve } from "node:path";
-import { existsSync, readFileSync } from "node:fs";
-import { registerHooks } from "node:module";
+import { pathToFileURL } from "node:url";
+import { resolve } from "node:path";
 import { useBroker } from "@novox/mesh-sdk/messaging";
 import { collectTools, toolKey, type ToolDefinition } from "@novox/mesh-sdk/tools";
 import type { Broker } from "@novox/mesh-sdk/messaging";
 import { atWork, seatToolSubject, type Credential, type RuntimeBroker } from "./broker-nats.js";
 import { launch, launches } from "./launch.js";
+import { announce, endpointsOf, type ServedSeatVerb } from "./announce.js";
 
 /**
  * The one verb every module's runtime answers for it (novox/hq ADR 0152, design 34 §3): the
@@ -61,6 +60,39 @@ export interface RuntimeOptions {
    *  (novox/hq ADR 0159). Absent for a runtime started by hand, which then serves no seat its
    *  memberships do not name. */
   credential?: Credential;
+  /** What each served module's bundles are given (novox/hq ADR 0192): module → words, composed by
+   *  the mesh per machine. A module absent here is given the runtime's own words and nothing more. */
+  envs?: ReadonlyMap<string, Readonly<Record<string, string>>>;
+}
+
+/** The variable the mesh composes every served module's environment into, as JSON (ADR 0192). Read
+ *  once at start and removed from the process's environment, so no bundle finds another's there. */
+export const TOOL_ENV = "MESH_TOOL_ENV";
+
+/** Read and remove the composed environments from an environment (the process's, by default). */
+export function takeToolEnvs(env: NodeJS.ProcessEnv = process.env): Map<string, Record<string, string>> {
+  const raw = env[TOOL_ENV];
+  delete env[TOOL_ENV];
+  const out = new Map<string, Record<string, string>>();
+  if (!raw) return out;
+  let parsed: unknown;
+  try {
+    parsed = JSON.parse(raw);
+  } catch {
+    throw new Error(`${TOOL_ENV} is not JSON; the mesh composes it as {"<module>": {"<word>": "<value>"}}`);
+  }
+  if (!parsed || typeof parsed !== "object" || Array.isArray(parsed)) {
+    throw new Error(`${TOOL_ENV} is not an object of modules`);
+  }
+  for (const [module, words] of Object.entries(parsed as Record<string, unknown>)) {
+    if (!words || typeof words !== "object" || Array.isArray(words)) {
+      throw new Error(`${TOOL_ENV}: ${module}'s environment is not an object of words`);
+    }
+    const own: Record<string, string> = {};
+    for (const [k, v] of Object.entries(words as Record<string, unknown>)) own[k] = String(v);
+    out.set(module, own);
+  }
+  return out;
 }
 
 /** Two environment words the mesh sets for the node's runtime and every tool reads from its
@@ -81,6 +113,7 @@ export async function runTools(opts: RuntimeOptions): Promise<() => void> {
   for (const s of opts.serves ?? []) {
     served.set(s.module, [...(served.get(s.module) ?? []), ...s.entrypoints]);
   }
+  const ownEntrypoints = opts.moduleEntrypoints ?? [];
   if (opts.moduleEntrypoints?.length) {
     if (!self) {
       throw new Error(
@@ -105,33 +138,42 @@ export async function runTools(opts: RuntimeOptions): Promise<() => void> {
     for (const module of served.keys()) await runtime.follow(module);
   }
 
-  // Import each bundle, guarded (ADR 0175: one faulty bundle must not take the node's tools down).
-  // Importing the entrypoint runs its registerModuleTools(...) — that is the whole handshake — and
-  // the registrations it adds are the ones that appear after it, which is how each is attributed
-  // to the module whose bundle made it.
-  // A bundle that is not plain JavaScript — or is marked executable — is launched as a process
-  // and spoken to over MCP on stdio instead (ADR 0188); what it lists is registered the same way.
-  // Every bundle's import of the SDK resolves to this runtime's copy (04-ISSUES/209): one registry
-  // of tools, one broker. Installed before the first bundle is imported.
-  oneSdk();
+  // What each module's bundles are given: the runtime's own words, and over them the module's own.
+  const envs = opts.envs ?? new Map<string, Record<string, string>>();
+  const envFor = (module: string): NodeJS.ProcessEnv => ({ ...process.env, ...(envs.get(module) ?? {}) });
+
+  // Every bundle this runtime serves is launched as a process and spoken to over MCP on stdio (ADR
+  // 0188, ADR 0193): given the runtime's words and its module's own, and told the module it serves
+  // it as. The runtime knows no language; an entrypoint that is not executable was not built to be
+  // served, and is refused by name. A bundle that fails to start is named, and the others serve
+  // (ADR 0175: one faulty bundle must not take the node's tools down).
+  //
+  // The one-module form — the credential's own module's entrypoints, which the per-module containers
+  // still use for their event handlers and provisioners until they move (to-be 38 WP4c) — is imported
+  // into this process as before: one module, one SDK, its container's own environment.
+  // The machine this runtime serves, which an event a launched tool emits is stamped with.
+  const node = opts.credential?.node ?? (typeof (runtime as unknown as { node?: unknown }).node === "string" ? (runtime as unknown as { node: string }).node : undefined);
   const failed = new Map<string, string>();
-  const owner: string[] = []; // registration index → the module whose bundle registered it
   const launched: { module: string; owner: string; tools: ToolDefinition[] }[] = [];
   const children: Array<() => void> = [];
   for (const [module, entrypoints] of served) {
+    const imported = module === self && ownEntrypoints.length > 0;
     for (const entry of entrypoints) {
       const path = resolve(entry);
       try {
-        if (launches(path)) {
-          const child = await launch(module, path);
-          children.push(child.stop);
-          for (const r of child.registrations) launched.push({ ...r, owner: module });
+        if (imported) {
+          await import(pathToFileURL(path).href);
           continue;
         }
-        const before = collectTools().length;
-        await import(pathToFileURL(path).href);
-        const after = collectTools().length;
-        for (let i = before; i < after; i++) owner[i] = module;
+        if (!launches(path)) {
+          throw new Error(`${path} is not executable; a bundle the runtime serves is started, never imported, and its build makes it executable (novox/hq ADR 0193)`);
+        }
+        const child = await launch(module, path, {
+          ...envFor(module), MESH_SERVED_MODULE: module, MESH_MODULE: module,
+          ...(node ? { MESH_NODE: node } : {}),
+        });
+        children.push(child.stop);
+        for (const r of child.registrations) launched.push({ ...r, owner: module });
       } catch (err) {
         const why = err instanceof Error ? err.message : String(err);
         failed.set(module, why);
@@ -149,7 +191,7 @@ export async function runTools(opts: RuntimeOptions): Promise<() => void> {
   // implement a seat did not yet name the claim, and the whole runtime restarted for it.
   const claimed = seatsClaimed(served.keys(), self, opts.credential, runtime);
   const registrations = [
-    ...collectTools().map((r, i) => ({ ...r, owner: owner[i] ?? self ?? r.module })),
+    ...collectTools().map((r) => ({ ...r, owner: self ?? r.module })),
     ...launched,
   ];
   const ownRegistrations = registrations.filter(({ module, owner: by }) => {
@@ -218,7 +260,16 @@ export async function runTools(opts: RuntimeOptions): Promise<() => void> {
 
   console.log(`[mesh-tools] serving ${names.length} tool(s) for ${served.size} module(s): ${names.join(", ") || "(none)"}` +
     (failed.size ? `; not serving ${[...failed.keys()].join(", ")}, whose bundle(s) failed to load` : ""));
-  stops.push(await serveClaimedSeats(runtime, [...served.keys()], self, opts.credential, registrations));
+  const seats = await serveClaimedSeats(runtime, [...served.keys()], self, opts.credential, registrations);
+  stops.push(seats.stop);
+  // **What it serves, it announces** (novox/hq ADR 0197), asked at the moment of the request.
+  if (typeof runtime.raw === "function") {
+    stops.push(announce(runtime, {
+      name: self ?? "runtime", id: runtime.node ?? self ?? "runtime",
+      description: `the tool runtime of ${self ?? "a module"}${runtime.node ? ` on ${runtime.node}` : ""}`,
+      metadata: runtime.node ? { node: runtime.node } : {},
+    }, () => endpointsOf(runtime, ownRegistrations, seats.serving())));
+  }
   return () => stop();
 }
 
@@ -262,11 +313,17 @@ async function serveClaimedSeats(
   self: string | undefined,
   credential: Credential | undefined,
   registrations: { module: string; owner: string; tools: ToolDefinition[] }[],
-): Promise<() => void> {
-  if (typeof broker.handleSubject !== "function") return () => {};
+): Promise<{ stop: () => void; serving: () => ServedSeatVerb[] }> {
+  if (typeof broker.handleSubject !== "function") return { stop: () => {}, serving: () => [] };
   // A seat's verbs are the role's, not the software's (ADR 0159): implemented under the seat's
   // name — `registerModuleTools("mesh-store", …)` — and never confused with the module's own tools.
   const implementations = new Map<string, Map<string, (args: Record<string, unknown>) => Promise<unknown>>>();
+  const definitions = new Map<string, Map<string, ToolDefinition>>();
+  for (const { module, tools } of registrations) {
+    const defs = definitions.get(module) ?? new Map<string, ToolDefinition>();
+    for (const t of tools) defs.set(t.name, t);
+    definitions.set(module, defs);
+  }
   for (const { module, owner, tools } of registrations) {
     const verbs = implementations.get(module) ?? new Map<string, (args: Record<string, unknown>) => Promise<unknown>>();
     for (const t of tools) verbs.set(t.name, (args) => atWork.run({ module: owner }, () => t.run(args)));
@@ -285,13 +342,16 @@ async function serveClaimedSeats(
     for (const module of served) {
       const m = typeof broker.membership === "function" ? broker.membership(module) : undefined;
       for (const s of m?.seats ?? []) add({ seat: s.seat, verb: s.verb, subject: s.subject, holder: module });
-      // The credential's claims, for the module's own runtime: where the mesh issued the verb when
-      // it has; the derived shape until then.
-      if (module !== self) continue;
+      // The credential's claims, for the module's own runtime, ONLY until the mesh issues a
+      // membership (novox/hq issue 218). The credential names what the module claims; the membership
+      // names what it holds on this machine. A seat held once for the mesh is claimed by every
+      // machine running the module and held by one, so once a membership exists it decides: a claim
+      // it leaves out is not held here, and serving it anyway announced the seat from a machine the
+      // bus then refused it on.
+      if (module !== self || m) continue;
       for (const claim of credential?.claims ?? []) {
         for (const verb of claim.serves ?? []) {
-          const subject = m?.seats?.find((s) => s.seat === claim.seat && s.verb === verb)?.subject
-            ?? seatToolSubject(claim.seat, verb, claim.scope, credential?.node);
+          const subject = seatToolSubject(claim.seat, verb, claim.scope, credential?.node);
           add({ seat: claim.seat, verb, subject, holder: module });
         }
       }
@@ -300,81 +360,25 @@ async function serveClaimedSeats(
   };
 
   let stops: (() => void)[] = [];
+  let servingNow: ServedSeatVerb[] = [];
   const serve = async (): Promise<void> => {
     stops.forEach((s) => s());
     stops = [];
+    servingNow = [];
     for (const v of wanted()) {
       const run = implementations.get(v.seat)?.get(v.verb);
+      const tool = definitions.get(v.seat)?.get(v.verb);
       if (!run) {
         console.log(`[mesh-tools] ${v.holder} claims ${v.seat} and implements no ${v.verb}, which that seat promises; not served`);
         continue;
       }
       stops.push(await broker.handleSubject(v.subject, run));
+      if (tool) servingNow.push({ ...v, tool });
       console.log(`[mesh-tools] serving ${v.seat}'s ${v.verb} on ${v.subject}, admitted where ${v.holder} holds the seat`);
     }
   };
   await serve();
   // A membership issued to any served module may add, move or withdraw a seat's verbs.
   if (typeof broker.onMembership === "function") broker.onMembership(() => void serve());
-  return () => stops.forEach((s) => s());
-}
-
-let sdkHooked = false;
-const SDK = "@novox/mesh-sdk";
-/**
- * The one SDK in a node's runtime (novox/hq ADR 0175, 04-ISSUES/209).
- *
- * A bundle carries its own dependencies — the toolchain copies them in so a bundle starts anywhere
- * (to-be 38 WP3) — and among them is a copy of the SDK. Imported in this process, that copy would be
- * a second SDK: its own registry of tools, its own broker handle. A bundle calling registerModuleTools
- * through it registers into a list this runtime never reads, and its tools are silently not served.
- * So every import of the SDK, from whichever bundle, is resolved as if this runtime had written it:
- * one registry, one broker — the runtime's. Everything else a bundle carries resolves from the
- * bundle's own tree, as before. A launched bundle (ADR 0188) is another process and is untouched.
- *
- * Installed once, in-thread, before the first bundle is imported; the hook sees every import after,
- * `require` included. A bundle whose own copy is another version than the runtime's is said once,
- * so a tool failing against the runtime's SDK points at the bundle rather than at the runtime.
- */
-function oneSdk(): void {
-  if (sdkHooked) return;
-  registerHooks({
-    resolve(specifier, context, next) {
-      if (specifier === SDK || specifier.startsWith(SDK + "/")) {
-        if (context.parentURL) sayOtherSdk(context.parentURL);
-        return next(specifier, { ...context, parentURL: import.meta.url });
-      }
-      return next(specifier, context);
-    },
-  });
-  sdkHooked = true;
-}
-
-const sdkSaid = new Set<string>();
-/** The version of the SDK copy nearest a file, by its package.json, or nothing when the file has none above it. */
-function sdkVersionNear(fileURL: string): { dir: string; version: string } | undefined {
-  let dir = dirname(fileURLToPath(fileURL));
-  for (;;) {
-    const pkg = join(dir, "node_modules", SDK, "package.json");
-    if (existsSync(pkg)) {
-      try {
-        return { dir, version: String((JSON.parse(readFileSync(pkg, "utf8")) as { version?: string }).version ?? "?") };
-      } catch {
-        return { dir, version: "?" };
-      }
-    }
-    const up = dirname(dir);
-    if (up === dir) return undefined;
-    dir = up;
-  }
-}
-function sayOtherSdk(parentURL: string): void {
-  if (!parentURL.startsWith("file:")) return;
-  const own = sdkVersionNear(import.meta.url);
-  const theirs = sdkVersionNear(parentURL);
-  if (!theirs || !own || theirs.dir === own.dir || sdkSaid.has(theirs.dir)) return;
-  sdkSaid.add(theirs.dir);
-  if (theirs.version !== own.version) {
-    console.log(`[mesh-tools] ${theirs.dir} carries ${SDK} ${theirs.version}; this runtime's is ${own.version}, and the bundle speaks to the runtime's`);
-  }
+  return { stop: () => stops.forEach((s) => s()), serving: () => servingNow };
 }

node-tools/test/announce.test.ts

@@ -0,0 +1,69 @@
+/**
+ * What a runtime serves, it announces (novox/hq ADR 0197): the TypeScript runtime the per-module
+ * containers still run answers the NATS services protocol's discovery in the same shape as the Go
+ * tool runtime — its module's tools on every subject issued, and the seat verbs it serves.
+ *
+ *   MESH_TEST_NATS=nats://127.0.0.1:14232 node --test --experimental-strip-types test/announce.test.ts
+ */
+import assert from "node:assert/strict";
+import { test } from "node:test";
+import { fileURLToPath } from "node:url";
+import { connect, StringCodec } from "nats";
+
+import { resetTools } from "@novox/mesh-sdk/tools";
+
+import { connectNats, membershipSubject } from "../dist/broker-nats.js";
+import { runTools } from "../dist/runtime.js";
+
+const url = process.env.MESH_TEST_NATS;
+const fixture = (name: string) => fileURLToPath(new URL(`./fixtures/${name}`, import.meta.url));
+const sc = StringCodec();
+
+test("the runtime answers $SRV.INFO with what it serves, in the services protocol's format", async (t) => {
+  if (!url) return t.skip("MESH_TEST_NATS unset");
+  resetTools();
+  const nc = await connect({ servers: url });
+  const jsm = await nc.jetstreamManager();
+  try {
+    await jsm.streams.delete("ASSIGNMENTS");
+  } catch {
+    // none yet
+  }
+  await jsm.streams.add({ name: "ASSIGNMENTS", subjects: ["mesh.assignment.>"], max_msgs_per_subject: 1, allow_direct: true } as never);
+  await nc.jetstream().publish(membershipSubject("anchor", "shop"), sc.encode(JSON.stringify({
+    node: "anchor", module: "shop",
+    serves: [{ subject: "mesh.mod.shop.tool.{tool}.anchor" }, { subject: "mesh.mod.shop.tool.{tool}", queue: "serve.shop" }],
+    emits: "mesh.mod.shop.event.{event}", tools: "mesh.mod.shop.tool.tools",
+  })));
+  const shop = await connectNats({ url, node: "anchor", module: "shop" });
+  let stop = () => {};
+  try {
+    stop = await runTools({ broker: shop, moduleEntrypoints: [fixture("shop-tools.mjs")] });
+    const msg = await nc.request("$SRV.INFO.shop.anchor", sc.encode(""), { timeout: 2000 });
+    const info = JSON.parse(sc.decode(msg.data)) as {
+      type: string; name: string; id: string; version: string;
+      endpoints: { name: string; subject: string; queue_group: string; metadata: Record<string, string> }[];
+    };
+    assert.equal(info.type, "io.nats.micro.v1.info_response");
+    assert.equal(info.name, "shop");
+    assert.equal(info.id, "anchor");
+    assert.ok(info.version);
+    const price = info.endpoints.filter((e) => e.metadata.tool === "price").map((e) => `${e.subject}|${e.queue_group}`).sort();
+    assert.deepEqual(price, ["mesh.mod.shop.tool.price.anchor|", "mesh.mod.shop.tool.price|serve.shop"]);
+    const one = info.endpoints.find((e) => e.metadata.tool === "price")!;
+    assert.equal(one.metadata.kind, "tool");
+    assert.equal(one.metadata.module, "shop");
+    assert.equal(one.metadata.node, "anchor");
+    assert.equal(one.metadata.interchangeable, "true");
+    assert.ok(JSON.parse(one.metadata.schema).type === "object");
+    // Ping answers with the same identity; another service's request is not answered.
+    const ping = JSON.parse(sc.decode((await nc.request("$SRV.PING", sc.encode(""), { timeout: 2000 })).data));
+    assert.equal(ping.type, "io.nats.micro.v1.ping_response");
+    await assert.rejects(nc.request("$SRV.INFO.somebody-else", sc.encode(""), { timeout: 300 }));
+  } finally {
+    stop();
+    await shop.close();
+    await nc.close();
+    resetTools();
+  }
+});

node-tools/test/fixtures/clash-tools.serve.mjs

@@ -0,0 +1,5 @@
+#!/usr/bin/env node
+// The launcher the builder writes beside an entrypoint (novox/hq ADR 0193), for clash-tools.mjs.
+import { serveRegisteredOverStdio } from "@novox/mesh-sdk/stdio";
+await import("./clash-tools.mjs");
+await serveRegisteredOverStdio();

node-tools/test/fixtures/env-delta.mjs

@@ -0,0 +1,4 @@
+import { registerModuleTools } from "@novox/mesh-sdk/tools";
+registerModuleTools("delta", (env) => [
+  { name: "given", description: "what delta was given", input: {}, run: async () => ({ mine: env.DELTA_TOKEN_FILE ?? null, theirs: env.GAMMA_CONFIG_FILE ?? null }) },
+]);

node-tools/test/fixtures/env-delta.serve.mjs

@@ -0,0 +1,5 @@
+#!/usr/bin/env node
+// The launcher the builder writes beside an entrypoint (novox/hq ADR 0193), for env-delta.mjs.
+import { serveRegisteredOverStdio } from "@novox/mesh-sdk/stdio";
+await import("./env-delta.mjs");
+await serveRegisteredOverStdio();

node-tools/test/fixtures/env-gamma.mjs

@@ -0,0 +1,5 @@
+// A bundle that reads what it was given (novox/hq ADR 0192): its contributor's environment.
+import { registerModuleTools } from "@novox/mesh-sdk/tools";
+registerModuleTools("gamma", (env) => [
+  { name: "given", description: "what gamma was given", input: {}, run: async () => ({ mine: env.GAMMA_CONFIG_FILE ?? null, theirs: env.DELTA_TOKEN_FILE ?? null, runtime: env.MESH_OPERATOR_ACCOUNT ?? null, composed: env.MESH_TOOL_ENV ?? null }) },
+]);

node-tools/test/fixtures/env-gamma.serve.mjs

@@ -0,0 +1,5 @@
+#!/usr/bin/env node
+// The launcher the builder writes beside an entrypoint (novox/hq ADR 0193), for env-gamma.mjs.
+import { serveRegisteredOverStdio } from "@novox/mesh-sdk/stdio";
+await import("./env-gamma.mjs");
+await serveRegisteredOverStdio();

node-tools/test/fixtures/env-zeta.mjs

@@ -0,0 +1,6 @@
+#!/usr/bin/env node
+// Launched (ADR 0188): its environment is the child's own.
+import { serveStdio } from "@novox/mesh-sdk/stdio";
+await serveStdio("zeta", [
+  { name: "given", description: "what zeta was given", input: {}, run: async () => ({ mine: process.env.ZETA_URL ?? null, theirs: process.env.GAMMA_CONFIG_FILE ?? null, composed: process.env.MESH_TOOL_ENV ?? null }) },
+]);

node-tools/test/fixtures/flaky.serve.mjs

@@ -0,0 +1,7 @@
+#!/usr/bin/env node
+// A long-running bundle that keeps exiting (novox/hq ADR 0198): the runtime starts it again each time.
+import { appendFileSync } from "node:fs";
+import { serveStdio } from "@novox/mesh-sdk/stdio";
+appendFileSync(process.env.FLAKY_LOG, "started\n");
+setTimeout(() => process.exit(3), 300);
+await serveStdio("flaky", []);

node-tools/test/fixtures/many-alpha.serve.mjs

@@ -0,0 +1,5 @@
+#!/usr/bin/env node
+// The launcher the builder writes beside an entrypoint (novox/hq ADR 0193), for many-alpha.mjs.
+import { serveRegisteredOverStdio } from "@novox/mesh-sdk/stdio";
+await import("./many-alpha.mjs");
+await serveRegisteredOverStdio();

node-tools/test/fixtures/many-beta.serve.mjs

@@ -0,0 +1,5 @@
+#!/usr/bin/env node
+// The launcher the builder writes beside an entrypoint (novox/hq ADR 0193), for many-beta.mjs.
+import { serveRegisteredOverStdio } from "@novox/mesh-sdk/stdio";
+await import("./many-beta.mjs");
+await serveRegisteredOverStdio();

node-tools/test/fixtures/many-broken.serve.mjs

@@ -0,0 +1,5 @@
+#!/usr/bin/env node
+// The launcher the builder writes beside an entrypoint (novox/hq ADR 0193), for many-broken.mjs.
+import { serveRegisteredOverStdio } from "@novox/mesh-sdk/stdio";
+await import("./many-broken.mjs");
+await serveRegisteredOverStdio();

node-tools/test/fixtures/refusing-nats.conf

@@ -0,0 +1,10 @@
+# A bus that refuses one subject: what the mesh's grants do to a subject they do not name (issue 217).
+authorization {
+  users = [
+    { user: "runtime", password: "runtime", permissions: {
+        publish: { allow: [">"] }
+        subscribe: { allow: [">"], deny: ["$SRV.PING.>", "mesh.seat.held-elsewhere.>"] }
+    } }
+  ]
+}
+jetstream: enabled

node-tools/test/fixtures/served-seat-first.mjs

@@ -0,0 +1,8 @@
+#!/usr/bin/env node
+// A launched bundle registering its seat before its own tools, served through the SDK's loop
+// (novox/hq ADR 0193): which is the seat's and which the module's comes from the name it is given.
+import { registerModuleTools } from "@novox/mesh-sdk/tools";
+import { serveRegisteredOverStdio } from "@novox/mesh-sdk/stdio";
+registerModuleTools("node-shelf", () => [{ name: "list", description: "the shelf", input: {}, run: async () => ({ shelf: ["x"] }) }]);
+registerModuleTools("theta", (env) => [{ name: "own", description: "theta's", input: {}, run: async () => ({ theta: env.THETA_WORD ?? null }) }]);
+await serveRegisteredOverStdio();

node-tools/test/fixtures/shop-seat.serve.mjs

@@ -0,0 +1,5 @@
+#!/usr/bin/env node
+// The launcher the builder writes beside an entrypoint (novox/hq ADR 0193), for shop-seat.mjs.
+import { serveRegisteredOverStdio } from "@novox/mesh-sdk/stdio";
+await import("./shop-seat.mjs");
+await serveRegisteredOverStdio();

node-tools/test/fixtures/shop-tools.serve.mjs

@@ -0,0 +1,5 @@
+#!/usr/bin/env node
+// The launcher the builder writes beside an entrypoint (novox/hq ADR 0193), for shop-tools.mjs.
+import { serveRegisteredOverStdio } from "@novox/mesh-sdk/stdio";
+await import("./shop-tools.mjs");
+await serveRegisteredOverStdio();

node-tools/test/fixtures/store-claimant.mjs

@@ -0,0 +1,13 @@
+// A copy for the issue 218 test: a fixture registers once per process, at import.
+// A module that is both software and a role: postgres's own tools under its name, and its
+// implementation of the mesh-store seat's verbs under the seat's (novox/hq ADR 0159, 0160).
+import { registerModuleTools } from "@novox/mesh-sdk/tools";
+
+registerModuleTools("postgres", () => [
+  { name: "postgres_create_database", description: "make one", input: {}, run: async () => ({ made: true }) },
+  { name: "databases", description: "postgres's own listing", input: {}, run: async () => ({ software: "postgres" }) },
+]);
+
+registerModuleTools("mesh-store", () => [
+  { name: "databases", description: "what the store holds", input: {}, run: async () => ({ seat: "mesh-store" }) },
+]);

node-tools/test/fixtures/store-seat-unclaimed.serve.mjs

@@ -0,0 +1,5 @@
+#!/usr/bin/env node
+// The launcher the builder writes beside an entrypoint (novox/hq ADR 0193), for store-seat-unclaimed.mjs.
+import { serveRegisteredOverStdio } from "@novox/mesh-sdk/stdio";
+await import("./store-seat-unclaimed.mjs");
+await serveRegisteredOverStdio();

node-tools/test/fixtures/store-seat.serve.mjs

@@ -0,0 +1,5 @@
+#!/usr/bin/env node
+// The launcher the builder writes beside an entrypoint (novox/hq ADR 0193), for store-seat.mjs.
+import { serveRegisteredOverStdio } from "@novox/mesh-sdk/stdio";
+await import("./store-seat.mjs");
+await serveRegisteredOverStdio();

node-tools/test/fixtures/watcher.mjs

@@ -0,0 +1,24 @@
+// A module whose code runs long (novox/hq ADR 0198): it subscribes as it is imported, handles each
+// event once it can, fails the first time it is asked to, dies the first time it is told to, and one
+// tool asks another module's tool through the runtime. What it did is written to WATCH_LOG.
+import { appendFileSync, existsSync, writeFileSync } from "node:fs";
+import { on } from "@novox/mesh-sdk/events";
+import { broker } from "@novox/mesh-sdk/messaging";
+import { registerModuleTools } from "@novox/mesh-sdk/tools";
+
+const log = process.env.WATCH_LOG;
+const once = (mark) => {
+  const file = `${log}.${mark}`;
+  if (existsSync(file)) return false;
+  writeFileSync(file, "1");
+  return true;
+};
+appendFileSync(log, "started\n");
+await on("alpha.happened", async (e) => {
+  if (e.body.fail && once(`fail-${e.body.n}`)) throw new Error(`not yet ${e.body.n}`);
+  if (e.body.die && once(`die-${e.body.n}`)) process.exit(7);
+  appendFileSync(log, `handled ${e.body.n}\n`);
+});
+registerModuleTools("watcher", () => [
+  { name: "relay", description: "asks beta", input: {}, run: async () => broker().request("beta.three", {}) },
+]);

node-tools/test/fixtures/watcher.serve.mjs

@@ -0,0 +1,5 @@
+#!/usr/bin/env node
+// The launcher the builder writes beside an entrypoint (novox/hq ADR 0193), for watcher.mjs.
+import { serveRegisteredOverStdio } from "@novox/mesh-sdk/stdio";
+await import("./watcher.mjs");
+await serveRegisteredOverStdio();

node-tools/test/membership.test.ts

@@ -140,6 +140,36 @@ test("a seat's verbs are implemented under the seat's name, served where issued,
   }
 });
 
+// novox/hq issue 218: the store seat is claimed by every machine running postgres and held by one.
+// Where the mesh issued a membership without the seat, the claim in the credential serves nothing:
+// the module's own tools answer, the seat's verbs do not, and the runtime does not announce them.
+test("a claimant the membership does not make the holder serves none of the seat's verbs", async (t) => {
+  if (!url) return t.skip("MESH_TEST_NATS unset");
+  resetTools();
+  const stream = await anAssignmentsStream();
+  await stream.issue({
+    node: "elsewhere",
+    module: "postgres",
+    serves: [{ subject: "mesh.mod.postgres.tool.{tool}.elsewhere" }],
+    emits: "mesh.mod.postgres.event.{event}",
+    tools: "mesh.mod.postgres.tool.tools",
+  });
+  const credential = { url, node: "elsewhere", module: "postgres", claims: [{ seat: "mesh-store", scope: "mesh", serves: ["databases", "query"] }] };
+  const pg = await connectNats(credential);
+  const asker = await connectNats({ url, module: "console", node: "workstation" });
+  let stop = () => {};
+  try {
+    stop = await runTools({ broker: pg, credential, moduleEntrypoints: [fixture("store-claimant.mjs")] });
+    assert.deepEqual((await callTool(asker, "postgres.databases@elsewhere", {})).result, { software: "postgres" });
+    await assert.rejects(callTool(asker, "seat:mesh-store.databases", {}), /no responders|503/i, "the store is not held here");
+  } finally {
+    stop();
+    await asker.close();
+    await pg.close();
+    await stream.close();
+  }
+});
+
 test("a module named like its seat registers once, and answers as the module and as the seat", async (t) => {
   if (!url) return t.skip("MESH_TEST_NATS unset");
   resetTools();

node-tools/test/node-runtime.test.ts

@@ -21,7 +21,7 @@ import { resetTools } from "@novox/mesh-sdk/tools";
 import { connectNats, membershipSubject } from "../dist/broker-nats.js";
 import { callTool, toolsOn } from "../dist/client.js";
 import { servedModulesFrom } from "../dist/main.js";
-import { runTools } from "../dist/runtime.js";
+import { runTools, takeToolEnvs } from "../dist/runtime.js";
 
 const url = process.env.MESH_TEST_NATS;
 const fixture = (name: string) => fileURLToPath(new URL(`./fixtures/${name}`, import.meta.url));
@@ -122,9 +122,9 @@ test("the node's runtime serves five modules' bundles on one credential — two
       broker: nodeTools,
       credential,
       serves: [
-        { module: "alpha", entrypoints: [fixture("many-alpha.mjs")] },
-        { module: "beta", entrypoints: [fixture("many-beta.mjs")] },
-        { module: "gamma", entrypoints: [fixture("many-broken.mjs")] },
+        { module: "alpha", entrypoints: [fixture("many-alpha.serve.mjs")] },
+        { module: "beta", entrypoints: [fixture("many-beta.serve.mjs")] },
+        { module: "gamma", entrypoints: [fixture("many-broken.serve.mjs")] },
         { module: "delta", entrypoints: [fixture("many-delta.py")] },
         { module: "epsilon", entrypoints: [fixture("many-epsilon.mjs")] },
       ],
@@ -132,7 +132,7 @@ test("the node's runtime serves five modules' bundles on one credential — two
     console.log = log;
     assert.deepEqual(nodeTools.serving().sort(), ["alpha", "beta", "delta", "epsilon", "gamma", "node-tools"]);
     assert.ok(said.some((s) => /the operator's account here is somebody \(home \/home\/somebody\)/.test(s)), said.join("\n"));
-    assert.ok(said.some((s) => /gamma's bundle .*many-broken\.mjs failed to load: gamma's bundle cannot find its client; its tools are not served here/.test(s)), said.join("\n"));
+    assert.ok(said.some((s) => /gamma's bundle .*many-broken\.serve\.mjs failed to load: gamma's bundle exited \(1\): Error: gamma's bundle cannot find its client; its tools are not served here/.test(s)), said.join("\n"));
     assert.ok(said.some((s) => /serving 8 tool\(s\) for 5 module\(s\): alpha\.one, alpha\.two, beta\.three, beta\.four, beta\.five, delta\.greet, delta\.die, epsilon\.seven; not serving gamma/.test(s)), said.join("\n"));
 
     // Five tools answer, each where its module's membership says: alpha anywhere and here, beta here only.
@@ -163,7 +163,7 @@ test("the node's runtime serves five modules' bundles on one credential — two
 
     // `tools` answers for each: what alpha and beta serve, and why gamma serves nothing.
     const gamma = await asker.request<Record<string, never>, { module: string; tools: unknown[]; failed?: string }>("gamma.tools@anchor", {});
-    assert.deepEqual(gamma, { module: "gamma", tools: [], failed: "gamma's bundle cannot find its client" });
+    assert.deepEqual(gamma, { module: "gamma", tools: [], failed: "gamma's bundle exited (1): Error: gamma's bundle cannot find its client" });
     const beta = await asker.request<Record<string, never>, { tools: { name: string; subjects?: string[] }[] }>("beta.tools@anchor", {});
     assert.deepEqual(beta.tools.map((x) => x.name), ["three", "four", "five"]);
     assert.deepEqual(beta.tools[0]!.subjects, ["mesh.mod.beta.tool.three.anchor"]);
@@ -174,7 +174,7 @@ test("the node's runtime serves five modules' bundles on one credential — two
     try {
       const have = await toolsOn(asker);
       assert.deepEqual(have.tools.map((x) => `${x.module}.${x.name}`), ["alpha.one", "alpha.two", "beta.five", "beta.four", "beta.three", "delta.die", "delta.greet", "epsilon.seven"]);
-      assert.deepEqual(have.notAnswering, ["gamma (its tools bundle failed to load: gamma's bundle cannot find its client)", "mesh-controller (seat)"]);
+      assert.deepEqual(have.notAnswering, ["gamma (its tools bundle failed to load: gamma's bundle exited (1): Error: gamma's bundle cannot find its client)", "mesh-controller (seat)"]);
     } finally {
       await catalogue.close();
     }
@@ -215,6 +215,8 @@ test("a bundle carrying its own copy of the SDK registers into the runtime's reg
     writeFileSync(join(dir, "node_modules", "zeta-flavour", "package.json"), '{"name":"zeta-flavour","type":"module","main":"index.js"}\n');
     writeFileSync(join(dir, "node_modules", "zeta-flavour", "index.js"), 'export const flavour = "the bundle\'s own";\n');
     writeFileSync(join(dir, "package.json"), '{"type":"module","private":true}\n');
+    writeFileSync(join(dir, "index.serve.mjs"),
+      '#!/usr/bin/env node\nimport { serveRegisteredOverStdio } from "@novox/mesh-sdk/stdio";\nawait import("./index.js");\nawait serveRegisteredOverStdio();\n', { mode: 0o755 });
     writeFileSync(join(dir, "index.js"),
       'import { registerModuleTools } from "@novox/mesh-sdk/tools";\n' +
       'import { flavour } from "zeta-flavour";\n' +
@@ -228,7 +230,7 @@ test("a bundle carrying its own copy of the SDK registers into the runtime's reg
     const asker = await connectNats({ url, module: "console", node: "workstation" });
     closing.push(() => asker.close());
     console.log = (...a: unknown[]) => said.push(a.join(" "));
-    stop = await runTools({ broker: nodeTools, credential, serves: [{ module: "zeta", entrypoints: [join(dir, "index.js")] }] });
+    stop = await runTools({ broker: nodeTools, credential, serves: [{ module: "zeta", entrypoints: [join(dir, "index.serve.mjs")] }] });
     console.log = log;
     assert.ok(said.some((s) => /serving 1 tool\(s\) for 1 module\(s\): zeta\.probe/.test(s)), said.join("\n"));
     // The SDK is the runtime's (the registration arrived); the bundle's other dependency is its own.
@@ -241,3 +243,108 @@ test("a bundle carrying its own copy of the SDK registers into the runtime's reg
     resetTools();
   }
 });
+
+test("each bundle is given its own environment and none of another's, imported or launched (ADR 0192)", async (t) => {
+  if (!url) return t.skip("MESH_TEST_NATS unset");
+  resetTools();
+  const mesh = await aMesh();
+  for (const m of ["gamma", "delta", "zeta"]) await mesh.issue(membershipOf(m, "anchor"));
+  const credential = { url, node: "anchor", module: "node-tools" };
+  const nodeTools = await connectNats(credential);
+  const asker = await connectNats({ url, module: "console", node: "workstation" });
+  const log = console.log;
+  let stop = () => {};
+  const before = process.env.MESH_TOOL_ENV;
+  try {
+    process.env.MESH_OPERATOR_ACCOUNT = "somebody";
+    process.env.MESH_TOOL_ENV = JSON.stringify({
+      gamma: { GAMMA_CONFIG_FILE: "/var/lib/mesh/gamma/config.json" },
+      delta: { DELTA_TOKEN_FILE: "/var/lib/mesh/delta/token" },
+      zeta: { ZETA_URL: "http://127.0.0.1:3000" },
+    });
+    const envs = takeToolEnvs();
+    assert.equal(process.env.MESH_TOOL_ENV, undefined, "the composed environments were left in the process's");
+    console.log = () => {};
+    stop = await runTools({
+      broker: nodeTools, credential, envs,
+      serves: [
+        { module: "gamma", entrypoints: [fixture("env-gamma.serve.mjs")] },
+        { module: "delta", entrypoints: [fixture("env-delta.serve.mjs")] },
+        { module: "zeta", entrypoints: [fixture("env-zeta.mjs")] },
+      ],
+    });
+    console.log = log;
+    assert.deepEqual((await callTool(asker, "gamma.given@anchor", {})).result,
+      { mine: "/var/lib/mesh/gamma/config.json", theirs: null, runtime: "somebody", composed: null });
+    assert.deepEqual((await callTool(asker, "delta.given@anchor", {})).result,
+      { mine: "/var/lib/mesh/delta/token", theirs: null });
+    assert.deepEqual((await callTool(asker, "zeta.given@anchor", {})).result,
+      { mine: "http://127.0.0.1:3000", theirs: null, composed: null });
+  } finally {
+    console.log = log;
+    if (before === undefined) delete process.env.MESH_TOOL_ENV; else process.env.MESH_TOOL_ENV = before;
+    delete process.env.MESH_OPERATOR_ACCOUNT;
+    stop();
+    await asker.close();
+    await nodeTools.close();
+    await mesh.close();
+    resetTools();
+  }
+});
+
+test("a launched bundle is told the module it serves, so its seat's verbs stay the seat's (ADR 0193)", async (t) => {
+  if (!url) return t.skip("MESH_TEST_NATS unset");
+  resetTools();
+  const mesh = await aMesh();
+  await mesh.issue(membershipOf("theta", "anchor", { seats: { "node-shelf": ["list"] } }));
+  const credential = { url, node: "anchor", module: "node-tools" };
+  const nodeTools = await connectNats(credential);
+  const asker = await connectNats({ url, module: "console", node: "workstation" });
+  const log = console.log;
+  let stop = () => {};
+  try {
+    console.log = () => {};
+    stop = await runTools({ broker: nodeTools, credential, envs: new Map([["theta", { THETA_WORD: "given" }]]),
+      serves: [{ module: "theta", entrypoints: [fixture("served-seat-first.mjs")] }] });
+    console.log = log;
+    assert.deepEqual((await callTool(asker, "theta.own@anchor", {})).result, { theta: "given" });
+    assert.deepEqual((await callTool(asker, "seat:node-shelf.list@anchor", {})).result, { shelf: ["x"] });
+  } finally {
+    console.log = log;
+    stop();
+    await asker.close();
+    await nodeTools.close();
+    await mesh.close();
+    resetTools();
+  }
+});
+
+test("an entrypoint that is not executable is refused by name, and the others serve (ADR 0193)", async (t) => {
+  if (!url) return t.skip("MESH_TEST_NATS unset");
+  resetTools();
+  const mesh = await aMesh();
+  for (const m of ["alpha", "plain"]) await mesh.issue(membershipOf(m, "anchor"));
+  const credential = { url, node: "anchor", module: "node-tools" };
+  const nodeTools = await connectNats(credential);
+  const asker = await connectNats({ url, module: "console", node: "workstation" });
+  const said: string[] = [];
+  const log = console.log;
+  let stop = () => {};
+  try {
+    console.log = (...a: unknown[]) => said.push(a.join(" "));
+    stop = await runTools({ broker: nodeTools, credential, serves: [
+      { module: "alpha", entrypoints: [fixture("many-alpha.serve.mjs")] },
+      { module: "plain", entrypoints: [fixture("many-alpha.mjs")] },
+    ] });
+    console.log = log;
+    assert.ok(said.some((s) => /plain's bundle .*many-alpha\.mjs failed to load: .* is not executable; a bundle the runtime serves is started, never imported/.test(s)), said.join("\n"));
+    assert.deepEqual((await callTool(asker, "alpha.one@anchor", {})).result, { alpha: 1 });
+  } finally {
+    console.log = log;
+    stop();
+    await asker.close();
+    await nodeTools.close();
+    await mesh.close();
+    resetTools();
+  }
+});

node-tools/test/node-tools-serve.test.ts

@@ -36,7 +36,7 @@ test("as node-tools, serve loads the bundles and is the console on loopback", as
     env: {
       ...process.env,
       MESH_BROKER_FILE: credential,
-      MESH_TOOL_MODULES: `alpha=${fixture("many-alpha.mjs")}`,
+      MESH_TOOL_MODULES: `alpha=${fixture("many-alpha.serve.mjs")}`,
       MESH_CONSOLE_LISTEN: "127.0.0.1:0",
     },
     stdio: ["ignore", "pipe", "pipe"],

node-tools/test/refused.test.ts

@@ -0,0 +1,68 @@
+/**
+ * A refused announcement is said and never fatal (novox/hq 04-ISSUES/217): against a bus whose
+ * permissions refuse one discovery subject, the runtime's raw subscription is refused, logged, and
+ * the process keeps serving — its tools still answer.
+ *
+ *   docker run -d --rm --name t -p 14233:4222 -v $PWD/test/fixtures/refusing-nats.conf:/c.conf nats:2.10-alpine -c /c.conf
+ *   MESH_TEST_REFUSING_NATS=nats://127.0.0.1:14233 node --test --experimental-strip-types test/refused.test.ts
+ */
+import assert from "node:assert/strict";
+import { test } from "node:test";
+import { connectNats } from "../dist/broker-nats.js";
+import { callTool } from "../dist/client.js";
+
+const url = process.env.MESH_TEST_REFUSING_NATS;
+
+test("a refused discovery subscription is logged and the runtime serves on", async (t) => {
+  if (!url) return t.skip("MESH_TEST_REFUSING_NATS unset");
+  const bus = await connectNats({ url, user: "runtime", password: "runtime", module: "alpha", node: "anchor" });
+  const said: string[] = [];
+  const log = console.log;
+  console.log = (...a: unknown[]) => said.push(a.join(" "));
+  const crashed: unknown[] = [];
+  const onRejection = (e: unknown) => crashed.push(e);
+  process.on("unhandledRejection", onRejection);
+  try {
+    (bus as unknown as { raw: (s: string, f: () => Uint8Array | undefined) => () => void }).raw("$SRV.PING.>", () => undefined);
+    const stop = await bus.handle("alpha.ping", async () => ({ pong: true }));
+    for (let i = 0; i < 50 && !said.some((s) => s.includes("the bus refused $SRV.PING.>")); i++) await new Promise((r) => setTimeout(r, 50));
+    console.log = log;
+    assert.ok(said.some((s) => /the bus refused \$SRV\.PING\.>.*serves on/.test(s)), said.join("\n"));
+    assert.equal(crashed.length, 0, `the refusal escaped: ${String(crashed[0])}`);
+    stop();
+  } finally {
+    console.log = log;
+    process.off("unhandledRejection", onRejection);
+    await bus.close();
+  }
+});
+
+// novox/hq issue 218: a tool subject the grants leave out — a seat claimed here and held elsewhere —
+// is refused, said, and the module's other tools still answer.
+test("a refused tool subscription is logged and the module's other tools answer", async (t) => {
+  if (!url) return t.skip("MESH_TEST_REFUSING_NATS unset");
+  const bus = await connectNats({ url, user: "runtime", password: "runtime", module: "alpha", node: "anchor" });
+  const asker = await connectNats({ url, user: "runtime", password: "runtime", module: "console", node: "workstation" });
+  const said: string[] = [];
+  const log = console.log;
+  console.log = (...a: unknown[]) => said.push(a.join(" "));
+  const crashed: unknown[] = [];
+  const onRejection = (e: unknown) => crashed.push(e);
+  process.on("unhandledRejection", onRejection);
+  try {
+    const refused = await bus.handleSubject!("mesh.seat.held-elsewhere.tool.databases", async () => ({ seat: true }));
+    const stop = await bus.handle("alpha.ping", async () => ({ pong: true }));
+    for (let i = 0; i < 50 && !said.some((s) => s.includes("the bus refused mesh.seat.held-elsewhere")); i++) await new Promise((r) => setTimeout(r, 50));
+    console.log = log;
+    assert.ok(said.some((s) => /the bus refused mesh\.seat\.held-elsewhere\.tool\.databases.*serves on/.test(s)), said.join("\n"));
+    assert.equal(crashed.length, 0, `the refusal escaped: ${String(crashed[0])}`);
+    assert.deepEqual((await callTool(asker, "alpha.ping@anchor", {})).result, { pong: true });
+    stop();
+    refused();
+  } finally {
+    console.log = log;
+    process.off("unhandledRejection", onRejection);
+    await asker.close();
+    await bus.close();
+  }
+});