i3status-rust: no domain names in the icon file's comments (the catalogue check refuses them)

PAM lines written into login and passwd as blocks, so login unlocks the keyring
on both workstations; no daemon of its own; gcr's ssh agent named for the session
until the environment can say a runtime-directory path. Go tools unlocked, lock,
collections and ssh-keys, never reading a secret.

modules/avahi/README.md

@@ -0,0 +1,42 @@
+# avahi
+
+The local network's name and service discovery (mDNS/DNS-SD) as a module (novox/hq to-be 42 Phase 1,
+research 027).
+
+## What it owns
+
+- The `avahi` package.
+- `avahi-daemon.service`, running and enabled.
+
+## What it improves
+
+It was on all four machines and owned by none. It is now declared, and its tools show why discovery
+does not work today:
+
+- **The packet filter drops mDNS.** The mesh's filter has no rule for inbound UDP 5353 on any of the
+  four machines, so avahi announces this machine but hears no other machine's answers. A browse
+  finds nothing, and resolving even the machine's own `.local` name times out. A module's `listens`
+  can reach the private network, this machine or anywhere, but not the local link. Opening the port
+  to anywhere would answer the internet on a public machine, so the module opens nothing. This needs
+  a decision in novox/hq: a local-link source scope for `listens`. Until then, `avahi_status` reports
+  `inbound_mdns_accepted: false`, and browse and resolve say so whenever they hear nothing.
+
+## What it leaves found
+
+- **`nss-mdns` and `/etc/nsswitch.conf`.** An ordinary lookup reaches avahi only through the
+  `hosts:` line. That line is one ordered list shared by every name source: containers, files, DNS,
+  mDNS and the resolver daemon. The host can write a marked block into a file, but it cannot add a
+  member to a line. Owning the whole file would make this module the owner of every machine's name
+  resolution. On 2026-10-04 all four machines had the same file, with `mdns4_minimal` wired by hand
+  and nss-mdns installed. Both are left as found, and `avahi_status` reports the wiring.
+- `/etc/avahi/avahi-daemon.conf`, including each workstation's hand-set `allow-interfaces`, which
+  names that machine's own network interface.
+
+## Tools
+
+| tool | | answers |
+|---|---|---|
+| `avahi_status` | r | the daemon, its version and configuration, the `hosts:` line and whether mdns is on it, nss-mdns, whether the filter accepts inbound 5353, systemd-resolved beside it, and notes |
+| `avahi_browse` | r | every service announced in a few seconds (`avahi-browse -prt`), resolved where possible, narrowed to a type |
+| `avahi_resolve` | r | a `.local` name through avahi and through the name service side by side, or an address to its name |
+| `avahi_services` | r | what this machine publishes from `/etc/avahi/services` |

modules/avahi/cmd/avahi-tools/avahi.go

@@ -0,0 +1,353 @@
+package main
+
+// Avahi, the local network's name and service discovery (mDNS/DNS-SD), as a module (novox/hq to-be 42
+// Phase 1, research 027: "on all four, owned by none"). The module declares the package and the
+// daemon. Two things it does not declare, and these tools report instead:
+//
+//   - **The name service switch.** nss-mdns is what lets an ordinary lookup answer `<host>.local`, and
+//     it works only through the `hosts:` line of /etc/nsswitch.conf. That line is one ordered list
+//     shared by every name source on the machine (containers, files, DNS, mDNS, the resolver daemon),
+//     the host can write a marked block into a file but not a member into a line, and owning the whole
+//     file would make this module the owner of every machine's name resolution. So both stay as found
+//     (wired by hand, identically, on all four machines on 2026-10-04) and `avahi_status` says whether
+//     the wiring is there.
+//   - **The packet filter.** mDNS is multicast to UDP 5353 on the local link. The mesh's filter has no
+//     source scope for "the local link" — a module's `listens` reach the private network, this machine
+//     or anywhere — so it drops what other machines announce, and a browse hears nothing. Opening it to
+//     anywhere would answer the internet on a public machine. `avahi_status` reports whether inbound
+//     5353 is accepted; browse and resolve say so when they hear nothing.
+
+import (
+	"fmt"
+	"net"
+	"regexp"
+	"sort"
+	"strconv"
+	"strings"
+)
+
+// The files avahi and the name service read.
+const (
+	DaemonConf  = "/etc/avahi/avahi-daemon.conf"
+	ServicesDir = "/etc/avahi/services"
+	NSSwitch    = "/etc/nsswitch.conf"
+	Daemon      = "avahi-daemon.service"
+)
+
+// Status is the daemon, its configuration, the name service's wiring and the filter.
+type Status struct {
+	Daemon      map[string]string            `json:"daemon"`
+	Version     string                       `json:"version,omitempty"`
+	Config      map[string]map[string]string `json:"config"`
+	HostsLine   string                       `json:"nsswitch_hosts"`
+	MDNSWired   bool                         `json:"nss_mdns_wired"`
+	NSSMDNS     string                       `json:"nss_mdns_package,omitempty"`
+	InboundMDNS *bool                        `json:"inbound_mdns_accepted"`
+	FilterError string                       `json:"filter_error,omitempty"`
+	ResolvedOn  bool                         `json:"systemd_resolved_active"`
+	Notes       []string                     `json:"notes"`
+}
+
+// ParseINI reads avahi-daemon.conf's sections and their set keys; commented keys are defaults.
+func ParseINI(text string) map[string]map[string]string {
+	out := map[string]map[string]string{}
+	section := ""
+	for _, l := range lines(text) {
+		l = strings.TrimSpace(l)
+		switch {
+		case strings.HasPrefix(l, "#") || strings.HasPrefix(l, ";"):
+		case strings.HasPrefix(l, "[") && strings.HasSuffix(l, "]"):
+			section = strings.Trim(l, "[]")
+			out[section] = map[string]string{}
+		default:
+			if k, v, ok := strings.Cut(l, "="); ok && section != "" {
+				out[section][strings.TrimSpace(k)] = strings.TrimSpace(v)
+			}
+		}
+	}
+	return out
+}
+
+// HostsLine is the `hosts:` line of nsswitch.conf, and whether an mdns source is on it.
+func HostsLine(text string) (string, bool) {
+	for _, l := range lines(text) {
+		l = strings.TrimSpace(l)
+		if !strings.HasPrefix(l, "hosts:") {
+			continue
+		}
+		for _, f := range strings.Fields(strings.TrimPrefix(l, "hosts:")) {
+			if strings.HasPrefix(f, "mdns") {
+				return l, true
+			}
+		}
+		return l, false
+	}
+	return "", false
+}
+
+var mdnsAccept = regexp.MustCompile(`(?m)\budp dport (?:\{[^}\n]*\b(?:5353|mdns)\b[^}\n]*\}|(?:5353|mdns)\b)[^\n]*\baccept\b`)
+
+// InboundMDNS is whether a ruleset accepts UDP 5353 coming in.
+func InboundMDNS(ruleset string) bool { return mdnsAccept.MatchString(ruleset) }
+
+// GetStatus reads the daemon, its configuration, the name service and the packet filter.
+func (m *Machine) GetStatus() (Status, error) {
+	s := Status{Config: map[string]map[string]string{}, Notes: []string{}}
+	d, err := m.unitProps(Daemon, "LoadState", "ActiveState", "SubState", "UnitFileState", "MainPID")
+	if err != nil {
+		return s, err
+	}
+	s.Daemon = d
+	if v, err := m.Out("avahi-daemon", "--version"); err == nil {
+		s.Version = strings.TrimSpace(v)
+	}
+	if text, err := m.ReadFile(DaemonConf); err == nil {
+		s.Config = ParseINI(string(text))
+	}
+	if text, err := m.ReadFile(NSSwitch); err == nil {
+		s.HostsLine, s.MDNSWired = HostsLine(string(text))
+	}
+	if r := m.Run(bg(), "pacman", "-Q", "nss-mdns"); r.Status == 0 && r.Err == "" {
+		s.NSSMDNS = strings.TrimSpace(r.Stdout)
+	}
+	if rs, err := m.Root("nft", "list", "ruleset"); err == nil {
+		open := InboundMDNS(rs)
+		s.InboundMDNS = &open
+		if !open {
+			s.Notes = append(s.Notes, "the packet filter drops inbound UDP 5353: this machine announces itself but hears no other machine's mDNS")
+		}
+	} else {
+		s.FilterError = err.Error()
+	}
+	if p, err := m.unitProps("systemd-resolved.service", "ActiveState"); err == nil {
+		s.ResolvedOn = p["ActiveState"] == "active"
+	}
+	if s.MDNSWired && s.NSSMDNS == "" {
+		s.Notes = append(s.Notes, "nsswitch names mdns and nss-mdns is not installed: those lookups fail")
+	}
+	if !s.MDNSWired {
+		s.Notes = append(s.Notes, "nsswitch does not name mdns: ordinary lookups never ask avahi")
+	}
+	return s, nil
+}
+
+// Service is one service a browse found.
+type Service struct {
+	Interface string   `json:"interface"`
+	Protocol  string   `json:"protocol"`
+	Name      string   `json:"name"`
+	Type      string   `json:"type"`
+	Domain    string   `json:"domain"`
+	Host      string   `json:"host,omitempty"`
+	Address   string   `json:"address,omitempty"`
+	Port      int      `json:"port,omitempty"`
+	TXT       []string `json:"txt,omitempty"`
+	Resolved  bool     `json:"resolved"`
+}
+
+// unescape undoes avahi-browse -p's escaping: a special byte as a backslash and three decimals, any
+// other character after a backslash as itself. Decoded as bytes, so a name in UTF-8 stays whole.
+func unescape(s string) string {
+	out := make([]byte, 0, len(s))
+	for i := 0; i < len(s); i++ {
+		if s[i] == '\\' {
+			if d := s[i+1 : min(i+4, len(s))]; len(d) == 3 && isDigits(d) {
+				n, _ := strconv.Atoi(d)
+				out = append(out, byte(n))
+				i += 3
+				continue
+			}
+			if i+1 < len(s) {
+				out = append(out, s[i+1])
+				i++
+				continue
+			}
+		}
+		out = append(out, s[i])
+	}
+	return string(out)
+}
+
+func isDigits(s string) bool {
+	for _, c := range s {
+		if c < '0' || c > '9' {
+			return false
+		}
+	}
+	return true
+}
+
+var txtItem = regexp.MustCompile(`"((?:[^"\\]|\\.)*)"`)
+
+// ParseBrowse reads `avahi-browse -p -r`: `+` lines found, `=` lines resolved; a found service
+// that resolved is answered once, resolved.
+func ParseBrowse(out string) []Service {
+	byKey := map[string]int{}
+	services := []Service{}
+	for _, l := range lines(out) {
+		f := strings.Split(l, ";")
+		if len(f) < 6 || (f[0] != "+" && f[0] != "=") {
+			continue
+		}
+		s := Service{Interface: f[1], Protocol: f[2], Name: unescape(f[3]), Type: f[4], Domain: f[5]}
+		if f[0] == "=" && len(f) >= 9 {
+			s.Resolved, s.Host, s.Address = true, f[6], f[7]
+			s.Port, _ = strconv.Atoi(f[8])
+			if len(f) >= 10 {
+				for _, t := range txtItem.FindAllStringSubmatch(strings.Join(f[9:], ";"), -1) {
+					s.TXT = append(s.TXT, t[1])
+				}
+			}
+		}
+		key := strings.Join([]string{s.Interface, s.Protocol, s.Name, s.Type, s.Domain}, "\x00")
+		if i, seen := byKey[key]; seen {
+			if s.Resolved {
+				services[i] = s
+			}
+			continue
+		}
+		byKey[key] = len(services)
+		services = append(services, s)
+	}
+	sort.SliceStable(services, func(i, j int) bool {
+		if services[i].Type != services[j].Type {
+			return services[i].Type < services[j].Type
+		}
+		return services[i].Name < services[j].Name
+	})
+	return services
+}
+
+var serviceType = regexp.MustCompile(`^_[A-Za-z0-9-]+\._(tcp|udp)$`)
+
+// Browse listens for a few seconds and answers every service announced, resolved where it could be.
+func (m *Machine) Browse(seconds int, kind string) (map[string]any, error) {
+	args := []string{strconv.Itoa(seconds), "avahi-browse", "-p", "-r", "-t"}
+	if kind == "" {
+		args = append(args, "-a")
+	} else {
+		if !serviceType.MatchString(kind) {
+			return nil, fmt.Errorf("%q is not a service type such as _ssh._tcp", kind)
+		}
+		args = append(args, kind)
+	}
+	r := m.Run(bg(), "timeout", args...)
+	// timeout's 124 is the listening time ending, which is how a browse that keeps hearing ends.
+	if r.Err != "" || (r.Status != 0 && r.Status != 124) {
+		return nil, failure("avahi-browse", "avahi-browse", r)
+	}
+	services := ParseBrowse(r.Stdout)
+	out := map[string]any{"seconds": seconds, "count": len(services), "services": services}
+	if len(services) == 0 {
+		out["note"] = m.silenceNote()
+	}
+	return out, nil
+}
+
+// silenceNote says why nothing may have been heard, from the packet filter when it can be read.
+func (m *Machine) silenceNote() string {
+	if rs, err := m.Root("nft", "list", "ruleset"); err == nil && !InboundMDNS(rs) {
+		return "nothing was heard, and this machine's packet filter drops inbound UDP 5353 (mDNS): other machines' answers do not reach avahi"
+	}
+	return "nothing was heard on the local network"
+}
+
+// Resolve asks avahi for a name's address (or an address's name), and the name service the same,
+// so an answer avahi has and an ordinary lookup does not shows the switch unwired.
+func (m *Machine) Resolve(name, address string) (map[string]any, error) {
+	if (name == "") == (address == "") {
+		return nil, fmt.Errorf("give a name or an address")
+	}
+	out := map[string]any{}
+	var r Ran
+	if name != "" {
+		if !strings.HasSuffix(name, ".local") {
+			name += ".local"
+		}
+		out["name"] = name
+		r = m.Run(bg(), "avahi-resolve", "-n", name)
+	} else {
+		if net.ParseIP(address) == nil {
+			return nil, fmt.Errorf("%q is not an address", address)
+		}
+		out["address"] = address
+		r = m.Run(bg(), "avahi-resolve", "-a", address)
+	}
+	if r.Err != "" {
+		return nil, failure("avahi-resolve", "avahi-resolve", r)
+	}
+	// avahi-resolve says a failure on stderr and exits 0.
+	avahi := map[string]any{"answers": []string{}}
+	for _, l := range lines(r.Stdout) {
+		if f := strings.Fields(l); len(f) >= 2 {
+			avahi["answers"] = append(avahi["answers"].([]string), f[1])
+		}
+	}
+	if said := firstLine(r.Stderr); said != "" {
+		avahi["error"] = said
+	}
+	avahi["resolved"] = len(avahi["answers"].([]string)) > 0
+	out["avahi"] = avahi
+	if name != "" {
+		nss := map[string]any{"answers": []string{}}
+		g := m.Run(bg(), "getent", "hosts", name)
+		for _, l := range lines(g.Stdout) {
+			if f := strings.Fields(l); len(f) >= 1 {
+				nss["answers"] = append(nss["answers"].([]string), f[0])
+			}
+		}
+		nss["resolved"] = len(nss["answers"].([]string)) > 0
+		out["name_service"] = nss
+	}
+	if avahi["resolved"] == false {
+		out["note"] = m.silenceNote()
+	}
+	return out, nil
+}
+
+// Published is one service this machine announces from a file of /etc/avahi/services.
+type Published struct {
+	File  string   `json:"file"`
+	Name  string   `json:"name,omitempty"`
+	Types []string `json:"types"`
+	Ports []int    `json:"ports"`
+}
+
+var (
+	xmlName = regexp.MustCompile(`<name[^>]*>([^<]*)</name>`)
+	xmlType = regexp.MustCompile(`<type>([^<]*)</type>`)
+	xmlPort = regexp.MustCompile(`<port>(\d+)</port>`)
+)
+
+// Services is what this machine publishes from its service files.
+func (m *Machine) Services() (map[string]any, error) {
+	r := m.Run(bg(), "find", ServicesDir, "-mindepth", "1", "-maxdepth", "1", "-name", "*.service", "-printf", "%f\n")
+	if r.Err != "" || r.Status != 0 {
+		if strings.Contains(r.Stderr, "No such file") {
+			return map[string]any{"directory": ServicesDir, "published": []Published{}}, nil
+		}
+		return nil, failure("find", "find", r)
+	}
+	pub := []Published{}
+	names := lines(r.Stdout)
+	sort.Strings(names)
+	for _, n := range names {
+		text, err := m.ReadFile(ServicesDir + "/" + n)
+		if err != nil {
+			return nil, err
+		}
+		p := Published{File: n, Types: []string{}, Ports: []int{}}
+		if x := xmlName.FindStringSubmatch(string(text)); x != nil {
+			p.Name = x[1]
+		}
+		for _, t := range xmlType.FindAllStringSubmatch(string(text), -1) {
+			p.Types = append(p.Types, t[1])
+		}
+		for _, x := range xmlPort.FindAllStringSubmatch(string(text), -1) {
+			port, _ := strconv.Atoi(x[1])
+			p.Ports = append(p.Ports, port)
+		}
+		pub = append(pub, p)
+	}
+	return map[string]any{"directory": ServicesDir, "published": pub}, nil
+}

modules/avahi/cmd/avahi-tools/avahi_test.go

@@ -0,0 +1,165 @@
+package main
+
+import (
+	"strings"
+	"testing"
+)
+
+const browse = `+;enp6s0;IPv4;home\032server;_ssh._tcp;local
++;enp6s0;IPv4;Printer\046Co;_ipp._tcp;local
+=;enp6s0;IPv4;home\032server;_ssh._tcp;local;home-server.local;192.168.1.10;22;
+=;enp6s0;IPv4;Printer\046Co;_ipp._tcp;local;printer.local;192.168.1.20;631;"txtvers=1" "rp=ipp/print"
++;enp6s0;IPv6;Kitchen;_spotify-connect._tcp;local
+`
+
+func TestABrowseIsReadResolvedOnceAndUnescaped(t *testing.T) {
+	s := ParseBrowse(browse)
+	if len(s) != 3 {
+		t.Fatalf("%+v", s)
+	}
+	by := map[string]Service{}
+	for _, x := range s {
+		by[x.Name] = x
+	}
+	ssh := by["home server"]
+	if !ssh.Resolved || ssh.Address != "192.168.1.10" || ssh.Port != 22 || ssh.Host != "home-server.local" {
+		t.Fatalf("%+v", ssh)
+	}
+	ipp := by["Printer.Co"]
+	if strings.Join(ipp.TXT, ",") != "txtvers=1,rp=ipp/print" {
+		t.Fatalf("%+v", ipp)
+	}
+	if k := by["Kitchen"]; k.Resolved || k.Type != "_spotify-connect._tcp" {
+		t.Fatalf("%+v", k)
+	}
+	if unescape(`caf\195\169`) != "café" || unescape(`a\.b`) != "a.b" {
+		t.Fatal("unescape")
+	}
+}
+
+func TestABrowseThatHearsNothingSaysTheFilterDropsMDNS(t *testing.T) {
+	var calls []call
+	m := machine(fake(func(c call) Ran {
+		switch c.String() {
+		case "timeout 5 avahi-browse -p -r -t -a":
+			return Ran{Status: 124}
+		case "sudo -n nft list ruleset":
+			return Ran{Stdout: "table inet mesh {\n chain input {\n type filter hook input priority filter; policy drop;\n tcp dport 22 accept\n }\n}\n"}
+		}
+		return Ran{Status: 99}
+	}, &calls), 1000)
+	r, err := m.Browse(5, "")
+	if err != nil || r["count"] != 0 || !strings.Contains(r["note"].(string), "drops inbound UDP 5353") {
+		t.Fatalf("%v %v", r, err)
+	}
+	if _, err := m.Browse(5, "ssh; rm"); err == nil {
+		t.Fatal("not a service type")
+	}
+}
+
+func TestTheFilterIsReadForAnAcceptedInboundMDNS(t *testing.T) {
+	for rs, want := range map[string]bool{
+		"\t\tudp dport 5353 accept\n":                            true,
+		"\t\tiifname \"enp6s0\" udp dport { 53, 5353 } accept\n": true,
+		"\t\tudp dport mdns accept\n":                            true,
+		"\t\tudp dport 53 accept\n":                              false,
+		"\t\tudp dport 5353 drop\n":                              false,
+		"\t\tip saddr 10.0.0.0/8 udp dport 15353 accept\n":       false,
+	} {
+		if InboundMDNS(rs) != want {
+			t.Errorf("%q: %v", rs, !want)
+		}
+	}
+}
+
+func TestStatusNamesTheSwitchTheFilterAndTheDaemon(t *testing.T) {
+	m := machine(fake(func(c call) Ran {
+		switch {
+		case c.name == "systemctl" && c.args[1] == Daemon:
+			return Ran{Stdout: "LoadState=loaded\nActiveState=active\nUnitFileState=enabled\n"}
+		case c.name == "systemctl":
+			return Ran{Stdout: "ActiveState=inactive\n"}
+		case c.String() == "avahi-daemon --version":
+			return Ran{Stdout: "avahi-daemon 0.9-rc5\n"}
+		case c.String() == "pacman -Q nss-mdns":
+			return Ran{Stdout: "nss-mdns 0.15.1-2\n"}
+		case c.String() == "sudo -n nft list ruleset":
+			return Ran{Stdout: "udp dport 53 accept\n"}
+		}
+		return Ran{Status: 99}
+	}, nil), 1000)
+	files := map[string]string{
+		DaemonConf: "[server]\nuse-ipv4=yes\n#host-name=foo\nallow-interfaces=enp6s0\n[publish]\npublish-hinfo=no\n",
+		NSSwitch:   "passwd: files\nhosts: mymachines files dns mdns4_minimal [NOTFOUND=return] resolve [!UNAVAIL=return]\n",
+	}
+	m.ReadFile = func(p string) ([]byte, error) {
+		if s, ok := files[p]; ok {
+			return []byte(s), nil
+		}
+		return nil, errNoFile
+	}
+	s, err := m.GetStatus()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !s.MDNSWired || s.NSSMDNS != "nss-mdns 0.15.1-2" || s.InboundMDNS == nil || *s.InboundMDNS || s.Version != "avahi-daemon 0.9-rc5" {
+		t.Fatalf("%+v", s)
+	}
+	if s.Config["server"]["allow-interfaces"] != "enp6s0" || s.Config["server"]["host-name"] != "" || s.Daemon["ActiveState"] != "active" {
+		t.Fatalf("%+v", s.Config)
+	}
+	if len(s.Notes) != 1 || !strings.Contains(s.Notes[0], "drops inbound UDP 5353") {
+		t.Fatalf("%v", s.Notes)
+	}
+	if _, wired := HostsLine("hosts: files dns\n"); wired {
+		t.Fatal("no mdns on the line")
+	}
+}
+
+func TestResolveAsksAvahiAndTheNameServiceAndReadsAFailureFromStderr(t *testing.T) {
+	m := machine(byLine(map[string]Ran{
+		"avahi-resolve -n printer.local": {Stdout: "printer.local\t192.168.1.20\n"},
+		"getent hosts printer.local":     {Status: 2},
+		"avahi-resolve -n nowhere.local": {Stderr: "Failed to resolve host name 'nowhere.local': Timeout reached\n"},
+		"getent hosts nowhere.local":     {Status: 2},
+		"sudo -n nft list ruleset":       {Stdout: "udp dport 5353 accept\n"},
+		"avahi-resolve -a 192.168.1.20":  {Stdout: "192.168.1.20\tprinter.local\n"},
+	}, nil), 1000)
+	r, err := m.Resolve("printer", "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if r["avahi"].(map[string]any)["resolved"] != true || r["name_service"].(map[string]any)["resolved"] != false {
+		t.Fatalf("%v", r)
+	}
+	r, _ = m.Resolve("nowhere.local", "")
+	if a := r["avahi"].(map[string]any); a["resolved"] != false || !strings.Contains(a["error"].(string), "Timeout reached") || r["note"] != "nothing was heard on the local network" {
+		t.Fatalf("%v", r)
+	}
+	r, _ = m.Resolve("", "192.168.1.20")
+	if r["avahi"].(map[string]any)["answers"].([]string)[0] != "printer.local" {
+		t.Fatalf("%v", r)
+	}
+	for _, bad := range [][2]string{{"", ""}, {"a", "1.2.3.4"}, {"", "not-an-ip"}} {
+		if _, err := m.Resolve(bad[0], bad[1]); err == nil {
+			t.Errorf("%v accepted", bad)
+		}
+	}
+}
+
+func TestPublishedServicesAreReadFromTheirFiles(t *testing.T) {
+	m := machine(byLine(map[string]Ran{
+		"find /etc/avahi/services -mindepth 1 -maxdepth 1 -name *.service -printf %f\n": {Stdout: "ssh.service\n"},
+	}, nil), 1000)
+	m.ReadFile = func(string) ([]byte, error) {
+		return []byte(`<service-group><name replace-wildcards="yes">%h</name><service><type>_ssh._tcp</type><port>22</port></service></service-group>`), nil
+	}
+	r, err := m.Services()
+	if err != nil {
+		t.Fatal(err)
+	}
+	p := r["published"].([]Published)
+	if len(p) != 1 || p[0].Name != "%h" || p[0].Types[0] != "_ssh._tcp" || p[0].Ports[0] != 22 {
+		t.Fatalf("%+v", p)
+	}
+}

modules/avahi/cmd/avahi-tools/machine.go

@@ -0,0 +1,289 @@
+package main
+
+// The commands this bundle runs on its machine, and who runs them.
+//
+// Who asks. The node's tool runtime runs as the operator account, not root (novox/hq ADR 0175 §4),
+// and launches this binary as a process of its own (ADR 0188, ADR 0193) with the runtime's words —
+// HOME, a PATH, MESH_OPERATOR_ACCOUNT — and no session words. Reading needs nothing more; what only
+// root may do goes through `sudo -n`, as the packet filter's, the service manager's and the
+// intrusion prevention's tools do (to-be 38 WP4), and the `sudo` module is what declares that the
+// account may (to-be 42, research 027). A refusal is named by how it failed, never read as an
+// empty answer.
+//
+// The runner is injected, so every tool is tested over a fake one without the machine.
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"io/fs"
+	"os"
+	"os/exec"
+	"strings"
+	"time"
+)
+
+// Ran is what one command did: its output, its exit status, and why it never ran to an answer.
+type Ran struct {
+	Stdout string
+	Stderr string
+	Status int
+	// Err is "ENOENT" when the program is not there, or that it was ended for taking too long.
+	Err string
+}
+
+// Runner runs one command, so the tools can be tested without the machine.
+type Runner func(ctx context.Context, name string, args ...string) Ran
+
+// CallTimeout is how long one command may take: below the runtime's thirty-second call limit, so a
+// command that hangs is answered as such rather than as a call the runtime gave up on.
+const CallTimeout = 20 * time.Second
+
+// outputLimit bounds what one command may hand back, so a runaway listing cannot exhaust the
+// process; well above anything a tool answers.
+const outputLimit = 16 << 20
+
+type bounded struct {
+	bytes.Buffer
+	cut bool
+}
+
+func (b *bounded) Write(p []byte) (int, error) {
+	if room := outputLimit - b.Len(); room < len(p) {
+		if room > 0 {
+			b.Buffer.Write(p[:room])
+		}
+		b.cut = true
+		return len(p), nil
+	}
+	return b.Buffer.Write(p)
+}
+
+// ExecRunner runs a command on this machine, in the C locale so what is parsed is one language.
+func ExecRunner(ctx context.Context, name string, args ...string) Ran {
+	ctx, cancel := context.WithTimeout(ctx, CallTimeout)
+	defer cancel()
+	cmd := exec.CommandContext(ctx, name, args...)
+	cmd.Env = append(os.Environ(), "LC_ALL=C")
+	var out, errb bounded
+	cmd.Stdout, cmd.Stderr = &out, &errb
+	err := cmd.Run()
+	r := Ran{Stdout: out.String(), Stderr: errb.String()}
+	if ctx.Err() == context.DeadlineExceeded {
+		r.Status, r.Err = 124, fmt.Sprintf("no answer within %d s", int(CallTimeout.Seconds()))
+		return r
+	}
+	var exit *exec.ExitError
+	switch {
+	case err == nil:
+	case errors.As(err, &exit):
+		r.Status = exit.ExitCode()
+	case errors.Is(err, exec.ErrNotFound) || errors.Is(err, fs.ErrNotExist):
+		r.Status, r.Err = 127, "ENOENT"
+	default:
+		r.Status, r.Err = 126, err.Error()
+	}
+	return r
+}
+
+// Escalated is the command as it is run: as given when this process is root, else through sudo
+// without a prompt.
+func Escalated(uid int, name string, args ...string) (string, []string) {
+	if uid == 0 {
+		return name, args
+	}
+	return "sudo", append([]string{"-n", name}, args...)
+}
+
+// Machine is this machine as the tools see it: a runner, who this process is, and its files.
+type Machine struct {
+	Run      Runner
+	UID      int
+	User     string
+	Account  string
+	ReadFile func(path string) ([]byte, error)
+	Now      func() time.Time
+	Sleep    func(time.Duration)
+}
+
+// ThisMachine is the machine the runtime launched this bundle on.
+func ThisMachine() *Machine {
+	user := os.Getenv("USER")
+	if user == "" {
+		user = os.Getenv("LOGNAME")
+	}
+	account := strings.TrimSpace(os.Getenv("MESH_OPERATOR_ACCOUNT"))
+	if account == "" {
+		account = user
+	}
+	return &Machine{Run: ExecRunner, UID: os.Getuid(), User: user, Account: account, ReadFile: os.ReadFile, Now: time.Now, Sleep: time.Sleep}
+}
+
+// Out runs a command that only reads, and fails with what went wrong named.
+func (m *Machine) Out(name string, args ...string) (string, error) {
+	r := m.Run(context.Background(), name, args...)
+	if r.Status == 0 && r.Err == "" {
+		return r.Stdout, nil
+	}
+	return r.Stdout, failure(name, name, r)
+}
+
+// Root runs a command that needs root, escalated when this process is not.
+func (m *Machine) Root(name string, args ...string) (string, error) {
+	program, argv := Escalated(m.UID, name, args...)
+	r := m.Run(context.Background(), program, argv...)
+	if r.Status == 0 && r.Err == "" {
+		return r.Stdout, nil
+	}
+	return r.Stdout, failure(name, program, r)
+}
+
+// RootRan is Root's raw answer, for a command whose non-zero status is itself an answer.
+func (m *Machine) RootRan(name string, args ...string) (Ran, error) {
+	program, argv := Escalated(m.UID, name, args...)
+	r := m.Run(context.Background(), program, argv...)
+	if r.Err != "" || (program == "sudo" && sudoRefused(r)) {
+		return r, failure(name, program, r)
+	}
+	return r, nil
+}
+
+func sudoRefused(r Ran) bool {
+	return strings.HasPrefix(strings.TrimSpace(r.Stderr), "sudo:")
+}
+
+// failure names what failed by how it failed: the program missing is a spawn error, sudo missing
+// or refusing speaks for itself, and the rest is the command's own first line.
+func failure(cmd, program string, r Ran) error {
+	said := strings.TrimSpace(r.Stderr + "\n" + r.Stdout)
+	if r.Err == "ENOENT" {
+		if program == "sudo" {
+			return fmt.Errorf("%s needs root for this, and sudo is not installed here for the runtime's account to escalate with", cmd)
+		}
+		return fmt.Errorf("%s is not installed on this machine", cmd)
+	}
+	if r.Err != "" {
+		return fmt.Errorf("%s did not answer: %s", cmd, r.Err)
+	}
+	if program == "sudo" && sudoRefused(r) {
+		if strings.Contains(said, "command not found") {
+			return fmt.Errorf("%s is not installed on this machine", cmd)
+		}
+		return fmt.Errorf("%s needs root for this and the runtime's account may not run it without a prompt: %s", cmd, firstLine(said))
+	}
+	if line := firstLine(said); line != "" {
+		return fmt.Errorf("%s failed (%d): %s", cmd, r.Status, line)
+	}
+	return fmt.Errorf("%s failed with status %d", cmd, r.Status)
+}
+
+func firstLine(text string) string {
+	for _, l := range strings.Split(text, "\n") {
+		if l = strings.TrimSpace(l); l != "" {
+			return l
+		}
+	}
+	return ""
+}
+
+func lines(text string) []string {
+	var out []string
+	for _, l := range strings.Split(text, "\n") {
+		if l = strings.TrimRight(l, "\r"); strings.TrimSpace(l) != "" {
+			out = append(out, l)
+		}
+	}
+	return out
+}
+
+// text is a string argument; required says whether it may be absent. It is never something a
+// command would read as an option, which under sudo would be root's option.
+func text(args map[string]any, key string, required bool) (string, error) {
+	raw, present := args[key]
+	if !present || raw == nil {
+		if required {
+			return "", fmt.Errorf("%s is required", key)
+		}
+		return "", nil
+	}
+	s, ok := raw.(string)
+	if !ok {
+		return "", fmt.Errorf("%s must be a string", key)
+	}
+	s = strings.TrimSpace(s)
+	if required && s == "" {
+		return "", fmt.Errorf("%s is required", key)
+	}
+	if strings.HasPrefix(s, "-") || strings.ContainsRune(s, 0) || strings.ContainsAny(s, "\n\r") {
+		return "", fmt.Errorf("%s %q is not a value this tool passes on", key, s)
+	}
+	return s, nil
+}
+
+// whole is a whole-number argument with a default, kept within bounds.
+func whole(args map[string]any, key string, def, least, most int) (int, error) {
+	raw, present := args[key]
+	if !present || raw == nil {
+		return def, nil
+	}
+	f, ok := raw.(float64)
+	if !ok || f != float64(int(f)) {
+		return 0, fmt.Errorf("%s must be a whole number", key)
+	}
+	n := int(f)
+	if n < least {
+		return 0, fmt.Errorf("%s must be at least %d", key, least)
+	}
+	if n > most {
+		n = most
+	}
+	return n, nil
+}
+
+// flag is a boolean argument, false when absent.
+func flag(args map[string]any, key string) (bool, error) {
+	raw, present := args[key]
+	if !present || raw == nil {
+		return false, nil
+	}
+	b, ok := raw.(bool)
+	if !ok {
+		return false, fmt.Errorf("%s must be true or false", key)
+	}
+	return b, nil
+}
+
+// schema is a tool's input: its properties and the ones it requires.
+func schema(properties map[string]any, required ...string) map[string]any {
+	s := map[string]any{"type": "object", "properties": properties}
+	if len(required) > 0 {
+		s["required"] = required
+	}
+	return s
+}
+
+// unitProps reads a unit's properties as systemctl shows them.
+func (m *Machine) unitProps(unit string, props ...string) (map[string]string, error) {
+	args := []string{"show", unit, "--no-pager"}
+	for _, p := range props {
+		args = append(args, "--property="+p)
+	}
+	out, err := m.Out("systemctl", args...)
+	if err != nil {
+		return nil, err
+	}
+	return keyValues(out, "="), nil
+}
+
+// keyValues reads `key<sep>value` lines; a line without the separator is skipped.
+func keyValues(out, sep string) map[string]string {
+	kv := map[string]string{}
+	for _, l := range strings.Split(out, "\n") {
+		k, v, ok := strings.Cut(l, sep)
+		if ok {
+			kv[strings.TrimSpace(k)] = strings.TrimSpace(v)
+		}
+	}
+	return kv
+}

modules/avahi/cmd/avahi-tools/machine_test.go

@@ -0,0 +1,107 @@
+package main
+
+import (
+	"context"
+	"strings"
+	"testing"
+	"time"
+)
+
+// call is one command a fake runner was asked to run.
+type call struct {
+	name string
+	args []string
+}
+
+func (c call) String() string {
+	if len(c.args) == 0 {
+		return c.name
+	}
+	return c.name + " " + strings.Join(c.args, " ")
+}
+
+// fake is a runner answering by the command line it is given, recording every call.
+func fake(answer func(c call) Ran, calls *[]call) Runner {
+	return func(_ context.Context, name string, args ...string) Ran {
+		c := call{name, append([]string(nil), args...)}
+		if calls != nil {
+			*calls = append(*calls, c)
+		}
+		return answer(c)
+	}
+}
+
+// byLine answers from a table keyed by the whole command line, and refuses anything else as a
+// command the test did not expect.
+func byLine(table map[string]Ran, calls *[]call) Runner {
+	return fake(func(c call) Ran {
+		if r, ok := table[c.String()]; ok {
+			return r
+		}
+		return Ran{Status: 99, Stderr: "unexpected command: " + c.String()}
+	}, calls)
+}
+
+func machine(run Runner, uid int) *Machine {
+	return &Machine{Run: run, UID: uid, User: "operator", Account: "operator",
+		ReadFile: func(string) ([]byte, error) { return nil, errNoFile },
+		Now:      func() time.Time { return time.Date(2026, 10, 4, 12, 0, 0, 0, time.UTC) },
+		Sleep:    func(time.Duration) {}}
+}
+
+type noFile struct{}
+
+func (noFile) Error() string { return "no such file" }
+
+var errNoFile = noFile{}
+
+func TestAnActNeedingRootGoesThroughSudoWithoutAPromptUnlessThisIsRoot(t *testing.T) {
+	if p, a := Escalated(1000, "visudo", "-c"); p != "sudo" || strings.Join(a, " ") != "-n visudo -c" {
+		t.Fatalf("not root: %s %v", p, a)
+	}
+	if p, a := Escalated(0, "visudo", "-c"); p != "visudo" || strings.Join(a, " ") != "-c" {
+		t.Fatalf("root: %s %v", p, a)
+	}
+}
+
+func TestFailuresAreNamedNeverReadAsEmpty(t *testing.T) {
+	cases := []struct {
+		r    Ran
+		want string
+	}{
+		{Ran{Status: 127, Err: "ENOENT"}, "sudo is not installed here"},
+		{Ran{Status: 1, Stderr: "sudo: a password is required\n"}, "may not run it without a prompt: sudo: a password is required"},
+		{Ran{Status: 124, Err: "no answer within 20 s"}, "did not answer: no answer within 20 s"},
+		{Ran{Status: 2, Stderr: "boom\nmore"}, "failed (2): boom"},
+	}
+	for _, c := range cases {
+		m := machine(fake(func(call) Ran { return c.r }, nil), 1000)
+		if _, err := m.Root("thing"); err == nil || !strings.Contains(err.Error(), c.want) {
+			t.Errorf("%+v: %v, want %q", c.r, err, c.want)
+		}
+	}
+	m := machine(fake(func(call) Ran { return Ran{Status: 127, Err: "ENOENT"} }, nil), 1000)
+	if _, err := m.Out("thing"); err == nil || !strings.Contains(err.Error(), "thing is not installed") {
+		t.Errorf("a missing program: %v", err)
+	}
+}
+
+func TestAnArgumentIsNeverAnOption(t *testing.T) {
+	for _, bad := range []any{"-rf", "a\nb", 3.0} {
+		if _, err := text(map[string]any{"x": bad}, "x", true); err == nil {
+			t.Errorf("%v was accepted", bad)
+		}
+	}
+	if s, err := text(map[string]any{"x": " ok "}, "x", true); err != nil || s != "ok" {
+		t.Errorf("a plain value: %q %v", s, err)
+	}
+	if _, err := text(map[string]any{}, "x", true); err == nil {
+		t.Error("a missing required value was accepted")
+	}
+	if n, _ := whole(map[string]any{"n": 10000.0}, "n", 5, 1, 100); n != 100 {
+		t.Errorf("not bounded: %d", n)
+	}
+	if _, err := whole(map[string]any{"n": 0.0}, "n", 5, 1, 100); err == nil {
+		t.Error("below the least was accepted")
+	}
+}

modules/avahi/cmd/avahi-tools/main.go

@@ -0,0 +1,85 @@
+// avahi's tools bundle (novox/hq to-be 42 Phase 1, research 026/05): a process the node's runtime
+// launches and speaks MCP over stdio to, through the Go SDK (ADR 0188, ADR 0193). It reads the
+// daemon, the name service's wiring and the packet filter's view of mDNS, browses the local network
+// for services, resolves a name, and lists what the machine publishes. It changes nothing.
+package main
+
+import (
+	"context"
+	"fmt"
+	"os"
+
+	stdio "git.novox.be/novox/mesh-sdk/go"
+)
+
+// binaryName is what the build names this bundle's executable: the manifest's `binary`.
+const binaryName = "avahi-tools"
+
+func bg() context.Context { return context.Background() }
+
+func main() {
+	// An empty name serves as the module the runtime names (MESH_SERVED_MODULE): avahi.
+	if err := stdio.Serve("", tools(ThisMachine())); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
+
+func tools(m *Machine) []stdio.Tool {
+	return []stdio.Tool{
+		{
+			Name: "avahi_status",
+			Description: "The daemon's state and version, its configuration as set, the name service switch's hosts line and whether mdns is on it, " +
+				"whether nss-mdns is installed, whether the packet filter accepts inbound mDNS (UDP 5353), whether systemd-resolved runs beside it, " +
+				"and notes naming what keeps discovery from working.",
+			Input: schema(map[string]any{}),
+			Run:   func(map[string]any) (any, error) { return m.GetStatus() },
+		},
+		{
+			Name: "avahi_browse",
+			Description: "Listen on the local network for a few seconds (avahi-browse -prt) and answer every service announced, with interface, " +
+				"protocol, name, type, host, address, port and TXT where it resolved; narrowed to one service type when given. Hearing nothing says why it may be.",
+			Input: schema(map[string]any{
+				"seconds": map[string]any{"type": "integer", "description": "how long to listen (default 5, at most 15)"},
+				"type":    map[string]any{"type": "string", "description": "one service type, e.g. _ssh._tcp (optional)"},
+			}),
+			Run: func(args map[string]any) (any, error) {
+				n, err := whole(args, "seconds", 5, 1, 15)
+				if err != nil {
+					return nil, err
+				}
+				kind, err := text(args, "type", false)
+				if err != nil {
+					return nil, err
+				}
+				return m.Browse(n, kind)
+			},
+		},
+		{
+			Name: "avahi_resolve",
+			Description: "Resolve a .local name to its addresses through avahi, and through the name service (getent) beside it, or an address to its name. " +
+				"An answer from avahi that the name service lacks shows nsswitch unwired; no answer says why it may be.",
+			Input: schema(map[string]any{
+				"name":    map[string]any{"type": "string", "description": "a host name; .local is added when missing"},
+				"address": map[string]any{"type": "string", "description": "an address to name instead"},
+			}),
+			Run: func(args map[string]any) (any, error) {
+				name, err := text(args, "name", false)
+				if err != nil {
+					return nil, err
+				}
+				address, err := text(args, "address", false)
+				if err != nil {
+					return nil, err
+				}
+				return m.Resolve(name, address)
+			},
+		},
+		{
+			Name:        "avahi_services",
+			Description: "What this machine publishes from /etc/avahi/services: each file with the service's name, types and ports.",
+			Input:       schema(map[string]any{}),
+			Run:         func(map[string]any) (any, error) { return m.Services() },
+		},
+	}
+}

modules/avahi/cmd/avahi-tools/manifest_test.go

@@ -0,0 +1,26 @@
+package main
+
+// The module's shape (novox/hq to-be 42 Phase 1, research 027): the package and the daemon, and
+// nothing written into the name service switch or opened in the packet filter — avahi.go says why
+// neither can be declared safely today, and the tools report both instead.
+
+import "testing"
+
+func TestItDeclaresThePackageAndTheDaemonOnly(t *testing.T) {
+	m := manifest(t)
+	if p := m.resource(t, "package"); p["package"] != "avahi" {
+		t.Fatalf("%v", p)
+	}
+	d := m.resource(t, "daemon")
+	if d["unit"] != Daemon || d["state"] != "running" || d["boot"] != "enabled" {
+		t.Fatalf("%v", d)
+	}
+	for _, r := range m.Resources {
+		if r["path"] == NSSwitch || r["package"] == "nss-mdns" {
+			t.Fatalf("%v: the name service switch is left as found", r["id"])
+		}
+	}
+	if len(m.Resources) != 2 {
+		t.Fatalf("%v", m.Resources)
+	}
+}

modules/avahi/cmd/avahi-tools/shape_test.go

@@ -0,0 +1,80 @@
+package main
+
+import (
+	"encoding/json"
+	"os"
+	"testing"
+)
+
+type resource map[string]any
+
+type manifestShape struct {
+	Module       string           `json:"module"`
+	Version      string           `json:"version"`
+	Capabilities []string         `json:"capabilities"`
+	Claims       []map[string]any `json:"claims"`
+	Tools        []string         `json:"tools"`
+	Resources    []resource       `json:"resources"`
+	Build        struct {
+		Artifacts []map[string]any `json:"artifacts"`
+	} `json:"build"`
+}
+
+func manifest(t *testing.T) manifestShape {
+	t.Helper()
+	raw, err := os.ReadFile("../../module.json")
+	if err != nil {
+		t.Fatal(err)
+	}
+	var m manifestShape
+	if err := json.Unmarshal(raw, &m); err != nil {
+		t.Fatal(err)
+	}
+	return m
+}
+
+func (m manifestShape) resource(t *testing.T, id string) resource {
+	t.Helper()
+	for _, r := range m.Resources {
+		if r["id"] == id {
+			return r
+		}
+	}
+	t.Fatalf("no resource %s", id)
+	return nil
+}
+
+// TestToolsAreTheManifests holds the served tools and the manifest's list to one another, and the
+// bundle to the shape the builder compiles and the runtime loads.
+func TestToolsAreTheManifests(t *testing.T) {
+	m := manifest(t)
+	names := map[string]bool{}
+	for _, tool := range tools(machine(nil, 1000)) {
+		if names[tool.Name] {
+			t.Errorf("%s is served twice", tool.Name)
+		}
+		names[tool.Name] = true
+	}
+	for _, want := range m.Tools {
+		if !names[want] {
+			t.Errorf("the manifest lists %s and the bundle does not serve it", want)
+		}
+		delete(names, want)
+	}
+	if len(names) != 0 {
+		t.Errorf("served and not listed: %v", names)
+	}
+	var tools map[string]any
+	for _, a := range m.Build.Artifacts {
+		if a["name"] == "tools" {
+			tools = a
+		}
+	}
+	if tools == nil || tools["kind"] != "bundle" || tools["language"] != "go" || tools["system"] != "arch" ||
+		tools["from"] != "cmd/"+binaryName || tools["binary"] != binaryName {
+		t.Fatalf("the tools artifact: %v", tools)
+	}
+	if loads, _ := tools["loads"].([]any); len(loads) != 1 || loads[0] != binaryName {
+		t.Fatalf("loads: %v", tools["loads"])
+	}
+}

modules/avahi/go.mod

@@ -0,0 +1,5 @@
+module avahi
+
+go 1.22
+
+require git.novox.be/novox/mesh-sdk/go v0.1.6

modules/avahi/go.sum

@@ -0,0 +1,2 @@
+git.novox.be/novox/mesh-sdk/go v0.1.6 h1:9qzdYONYbJdWcu6sxQcq9v1LI0JxcfkiKYkMUzJSkVQ=
+git.novox.be/novox/mesh-sdk/go v0.1.6/go.mod h1:GFuZUElBZ9A++mxgIKo97aXXo+kV0uJ/UkbhQPPIbrY=

modules/avahi/module.json

@@ -0,0 +1,43 @@
+{
+  "module": "avahi",
+  "version": "1",
+  "capabilities": [
+    "package-manager",
+    "service-manager"
+  ],
+  "tools": [
+    "avahi_status",
+    "avahi_browse",
+    "avahi_resolve",
+    "avahi_services"
+  ],
+  "resources": [
+    {
+      "id": "package",
+      "type": "package",
+      "package": "avahi"
+    },
+    {
+      "id": "daemon",
+      "type": "service",
+      "unit": "avahi-daemon.service",
+      "state": "running",
+      "boot": "enabled"
+    }
+  ],
+  "build": {
+    "artifacts": [
+      {
+        "name": "tools",
+        "kind": "bundle",
+        "language": "go",
+        "system": "arch",
+        "from": "cmd/avahi-tools",
+        "binary": "avahi-tools",
+        "loads": [
+          "avahi-tools"
+        ]
+      }
+    ]
+  }
+}

modules/bluetooth/README.md

@@ -0,0 +1,53 @@
+# bluetooth
+
+Bluetooth on the two workstations (novox/hq research 027/02, to-be 42 phase 2 step 9).
+
+## Owns
+
+| what | where |
+|---|---|
+| the Bluetooth stack and its daemon | package `bluez` |
+| `bluetoothctl`, which the tools speak through | package `bluez-utils` |
+| the daemon, running and enabled | `bluetooth.service` |
+
+All official. `/etc/bluetooth/main.conf` is the package's file, unchanged on both workstations
+(every setting commented out). The module states nothing in it, so it declares nothing there.
+
+## Improves
+
+- **The stack is declared, not a dependency of something else.** On both workstations `bluez` is
+  installed only as a dependency. Removing the applet that pulled it in would have left it an orphan
+  for the next clean-up to take, and Bluetooth with it.
+- **An owner for the daemon**, running and enabled on both today with nothing recording why.
+- **Headphones from the mesh.** `bluetooth_connect` and `bluetooth_devices` (with battery) answer from
+  any machine, without the applet.
+
+## Tools
+
+All answer JSON; `(r)` reads, `(a)` acts. They run as the operator account. bluez's bus policy lets
+the account act; if it ever refuses (`AccessDenied`), the act is repeated through `sudo -n`. An act
+whose output says it failed (`Failed to …`, `org.bluez.Error…`, `not available`) is an error, whatever
+bluetoothctl's exit status.
+
+| tool | what |
+|---|---|
+| `bluetooth_controller` (r) | address, name, powered, discoverable, pairable, discovering |
+| `bluetooth_power` (r/a) | read, or switch the controller on or off |
+| `bluetooth_devices` (r) | all, paired, connected or trusted devices: kind, paired, bonded, trusted, blocked, connected, battery where reported |
+| `bluetooth_scan` (r) | discover for 1 to 15 s (default 8); the unpaired devices found, strongest signal first |
+| `bluetooth_connect` / `bluetooth_disconnect` (a) | one device; connect waits up to 15 s |
+| `bluetooth_trust` (a) | trust, or untrust |
+| `bluetooth_pair` (a) | pair with an agent that confirms nothing (headphones, speakers), then trust. A device that shows a code is paired from the desktop |
+| `bluetooth_remove` (a) | forget a device |
+
+## What changes when it is assigned
+
+Nothing on disk on either workstation: both packages are installed, and the service is enabled and
+running. `bluez` becomes explicitly the mesh's.
+
+## Leaves as found
+
+- The paired devices and their keys under `/var/lib/bluetooth` (bluez's state).
+- `blueman` on both workstations, and its applet, which the window manager's configuration starts.
+  That line is the `i3` module's to keep or drop.
+- `bluez-obex` and the AUR terminal client `bluetuith-bin` (with its `-debug`) on the laptop.

modules/bluetooth/cmd/bluetooth-tools/bluetooth.go

@@ -0,0 +1,281 @@
+package main
+
+import (
+	"fmt"
+	"regexp"
+	"sort"
+	"strconv"
+	"strings"
+	"time"
+)
+
+var macAddress = regexp.MustCompile(`^[0-9A-Fa-f]{2}(:[0-9A-Fa-f]{2}){5}$`)
+
+func addressOf(args map[string]any) (string, error) {
+	a, err := text(args, "address")
+	if err != nil {
+		return "", err
+	}
+	if !macAddress.MatchString(a) {
+		return "", fmt.Errorf("%q is not a Bluetooth address (six hex pairs separated by colons)", a)
+	}
+	return strings.ToUpper(a), nil
+}
+
+var ansi = regexp.MustCompile(`\x1b\[[0-9;]*[A-Za-z]|\x01|\x02`)
+
+// btFailed are the words bluetoothctl uses for an act that did not happen, whatever its exit status.
+var btFailed = regexp.MustCompile(`(?m)(Failed to \w+|not available|org\.bluez\.Error\.\w+|No default controller available)`)
+
+// bt runs bluetoothctl once, non-interactively, as the account; bluez's bus policy lets the
+// account act, and if it refuses, the act is run through sudo -n.
+func bt(timeout time.Duration, args ...string) (string, error) {
+	c := Cmd{Name: "bluetoothctl", Args: args, Timeout: timeout}
+	r := run(c)
+	if strings.Contains(r.Stdout+r.Stderr, "AccessDenied") || strings.Contains(r.Stdout+r.Stderr, "Not authorized") {
+		c.Root = true
+		r = run(c)
+	}
+	out := ansi.ReplaceAllString(r.Stdout+"\n"+r.Stderr, "")
+	if r.Error != "" {
+		return out, failure(c, r)
+	}
+	if strings.Contains(out, "No default controller available") {
+		return out, fmt.Errorf("this machine has no Bluetooth controller bluez can use: none is present, it is blocked (rfkill), or bluetooth.service is not running")
+	}
+	if m := btFailed.FindString(out); m != "" || r.Status != 0 {
+		said := strings.TrimSpace(out)
+		if said == "" {
+			said = fmt.Sprintf("exit status %d", r.Status)
+		}
+		return out, fmt.Errorf("bluetoothctl %s: %s", strings.Join(args, " "), tail(said, 1000))
+	}
+	return out, nil
+}
+
+// fields reads bluetoothctl's "\tKey: value" lines; a key seen twice keeps its first value.
+func fields(s string) map[string]string {
+	out := map[string]string{}
+	for _, l := range strings.Split(s, "\n") {
+		if !strings.HasPrefix(l, "\t") {
+			continue
+		}
+		k, v, ok := strings.Cut(strings.TrimSpace(l), ":")
+		if !ok {
+			continue
+		}
+		if _, seen := out[k]; !seen {
+			out[k] = strings.TrimSpace(v)
+		}
+	}
+	return out
+}
+
+func yes(v string) bool { return v == "yes" }
+
+// ControllerAnswer is what bluetooth_controller answers.
+type ControllerAnswer struct {
+	Address      string `json:"address"`
+	Name         string `json:"name"`
+	Alias        string `json:"alias"`
+	Powered      bool   `json:"powered"`
+	PowerState   string `json:"power_state,omitempty"`
+	Discoverable bool   `json:"discoverable"`
+	Pairable     bool   `json:"pairable"`
+	Discovering  bool   `json:"discovering"`
+}
+
+// Controller answers the default controller.
+func Controller() (ControllerAnswer, error) {
+	out, err := bt(CallTimeout, "show")
+	if err != nil {
+		return ControllerAnswer{}, err
+	}
+	c := ControllerAnswer{}
+	for _, l := range strings.Split(out, "\n") {
+		if f := strings.Fields(l); len(f) >= 2 && f[0] == "Controller" {
+			c.Address = f[1]
+			break
+		}
+	}
+	if c.Address == "" {
+		return ControllerAnswer{}, fmt.Errorf("bluetoothctl show answered no controller: %s", tail(strings.TrimSpace(out), 500))
+	}
+	f := fields(out)
+	c.Name, c.Alias, c.PowerState = f["Name"], f["Alias"], f["PowerState"]
+	c.Powered, c.Discoverable, c.Pairable, c.Discovering = yes(f["Powered"]), yes(f["Discoverable"]), yes(f["Pairable"]), yes(f["Discovering"])
+	return c, nil
+}
+
+// Power switches the controller on or off.
+func Power(on bool) (map[string]any, error) {
+	word := "off"
+	if on {
+		word = "on"
+	}
+	if _, err := bt(CallTimeout, "power", word); err != nil {
+		return nil, err
+	}
+	c, err := Controller()
+	if err != nil {
+		return nil, err
+	}
+	return map[string]any{"powered": c.Powered, "asked": word}, nil
+}
+
+// Device is one device bluez knows.
+type Device struct {
+	Address   string `json:"address"`
+	Name      string `json:"name"`
+	Icon      string `json:"kind,omitempty"`
+	Paired    bool   `json:"paired"`
+	Bonded    bool   `json:"bonded"`
+	Trusted   bool   `json:"trusted"`
+	Blocked   bool   `json:"blocked"`
+	Connected bool   `json:"connected"`
+	Battery   *int   `json:"battery_percent,omitempty"`
+	RSSI      *int   `json:"rssi,omitempty"`
+}
+
+var inParens = regexp.MustCompile(`\((-?[0-9]+)\)`)
+
+// number reads "0x50 (80)" or "-62" as a number.
+func number(v string) *int {
+	if m := inParens.FindStringSubmatch(v); m != nil {
+		v = m[1]
+	}
+	n, err := strconv.Atoi(strings.TrimSpace(v))
+	if err != nil {
+		return nil
+	}
+	return &n
+}
+
+// deviceInfo asks bluez for one device.
+func deviceInfo(address string) (Device, error) {
+	out, err := bt(CallTimeout, "info", address)
+	if err != nil {
+		return Device{}, err
+	}
+	f := fields(out)
+	d := Device{Address: address, Name: f["Name"], Icon: f["Icon"], Paired: yes(f["Paired"]), Bonded: yes(f["Bonded"]),
+		Trusted: yes(f["Trusted"]), Blocked: yes(f["Blocked"]), Connected: yes(f["Connected"])}
+	if d.Name == "" {
+		d.Name = f["Alias"]
+	}
+	if v, ok := f["Battery Percentage"]; ok {
+		d.Battery = number(v)
+	}
+	if v, ok := f["RSSI"]; ok {
+		d.RSSI = number(v)
+	}
+	return d, nil
+}
+
+// listed reads "Device <address> <name>" lines.
+func listed(out string) []string {
+	seen := map[string]bool{}
+	addrs := []string{}
+	for _, l := range strings.Split(out, "\n") {
+		f := strings.Fields(strings.TrimSpace(l))
+		if len(f) >= 2 && f[0] == "Device" && macAddress.MatchString(f[1]) && !seen[f[1]] {
+			seen[f[1]] = true
+			addrs = append(addrs, f[1])
+		}
+	}
+	return addrs
+}
+
+// Devices answers the devices bluez knows, with each one's state.
+func Devices(which string) (map[string]any, error) {
+	if err := oneOf("which", which, "all", "paired", "connected", "trusted"); err != nil {
+		return nil, err
+	}
+	args := []string{"devices"}
+	if which != "all" {
+		args = append(args, strings.ToUpper(which[:1])+which[1:])
+	}
+	out, err := bt(CallTimeout, args...)
+	if err != nil {
+		return nil, err
+	}
+	devices := []Device{}
+	for _, a := range listed(out) {
+		d, err := deviceInfo(a)
+		if err != nil {
+			return nil, err
+		}
+		devices = append(devices, d)
+	}
+	sort.SliceStable(devices, func(i, k int) bool {
+		if devices[i].Connected != devices[k].Connected {
+			return devices[i].Connected
+		}
+		return devices[i].Name < devices[k].Name
+	})
+	return map[string]any{"which": which, "count": len(devices), "devices": devices}, nil
+}
+
+// Scan discovers for a while and answers the devices found that are not paired.
+func Scan(seconds int) (map[string]any, error) {
+	// bluetoothctl's own --timeout ends the scan; the command's bound is a little longer.
+	limit := time.Duration(seconds+4) * time.Second
+	if _, err := bt(limit, "--timeout", strconv.Itoa(seconds), "scan", "on"); err != nil {
+		return nil, err
+	}
+	out, err := bt(CallTimeout, "devices")
+	if err != nil {
+		return nil, err
+	}
+	found := []Device{}
+	for _, a := range listed(out) {
+		// A device seen a moment ago may have gone out of reach: it is skipped, not a failure.
+		d, err := deviceInfo(a)
+		if err != nil {
+			continue
+		}
+		if !d.Paired {
+			found = append(found, d)
+		}
+	}
+	sort.SliceStable(found, func(i, k int) bool {
+		ri, rk := -1000, -1000
+		if found[i].RSSI != nil {
+			ri = *found[i].RSSI
+		}
+		if found[k].RSSI != nil {
+			rk = *found[k].RSSI
+		}
+		return ri > rk
+	})
+	return map[string]any{"seconds": seconds, "count": len(found), "found": found}, nil
+}
+
+// Act runs one act on a device and answers the device's state afterwards.
+func Act(verb, address string) (map[string]any, error) {
+	limit := CallTimeout
+	if verb == "connect" {
+		// A connect waits for the device; bluetoothctl's own timeout ends it first.
+		if _, err := bt(limit, "--timeout", "15", verb, address); err != nil {
+			return nil, err
+		}
+	} else if _, err := bt(limit, verb, address); err != nil {
+		return nil, err
+	}
+	if verb == "remove" {
+		return map[string]any{"act": verb, "address": address, "removed": true}, nil
+	}
+	d, err := deviceInfo(address)
+	if err != nil {
+		return nil, err
+	}
+	return map[string]any{"act": verb, "device": d}, nil
+}
+
+// Pair pairs a device with an agent that confirms nothing, then trusts it.
+func Pair(address string) (map[string]any, error) {
+	if _, err := bt(CallTimeout, "--agent", "NoInputNoOutput", "--timeout", "15", "pair", address); err != nil {
+		return nil, err
+	}
+	return Act("trust", address)
+}

modules/bluetooth/cmd/bluetooth-tools/bluetooth_test.go

@@ -0,0 +1,163 @@
+package main
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestTheManifestIsTheStackItsToolsAndTheDaemon(t *testing.T) {
+	m := readManifest(t)
+	holdsTheBundle(t, m, "bluetooth")
+	if got := strings.Join(m.packages(), ","); got != "bluez,bluez-utils" {
+		t.Errorf("packages %s: the applet and the TUI are the operator's", got)
+	}
+	s := m.services()["bluetooth.service"]
+	if s == nil || s["state"] != "running" || s["boot"] != "enabled" {
+		t.Errorf("%v", s)
+	}
+	if len(m.Resources) != 3 {
+		t.Errorf("no configuration file: /etc/bluetooth/main.conf is the package's, unchanged on both workstations: %v", m.Resources)
+	}
+}
+
+const show = "Controller 4C:82:A9:97:01:8E (public)\n\tName: g14\n\tAlias: g14\n\tPowered: yes\n\tPowerState: on\n\tDiscoverable: no\n\tPairable: yes\n\tUUID: Headset (00001108-0000-1000-8000-00805f9b34fb)\n\tDiscovering: no\n"
+
+func headphones(connected bool) string {
+	c := "no"
+	extra := ""
+	if connected {
+		c, extra = "yes", "\tBattery Percentage: 0x50 (80)\n"
+	}
+	return "Device 80:99:E7:C2:29:DA (public)\n\tName: WH-1000XM4\n\tAlias: WH-1000XM4\n\tIcon: audio-headset\n\tPaired: yes\n\tBonded: yes\n\tTrusted: yes\n\tBlocked: no\n\tConnected: " + c + "\n" + extra + "\tUUID: Headset (00001108-0000-1000-8000-00805f9b34fb)\n"
+}
+
+func TestControllerReadsShow(t *testing.T) {
+	using(t, func(string, Cmd) Result { return ok("\x1b[0;94m" + show) })
+	c, err := Controller()
+	if err != nil || c.Address != "4C:82:A9:97:01:8E" || c.Name != "g14" || !c.Powered || c.Discoverable || !c.Pairable {
+		t.Fatalf("%+v %v", c, err)
+	}
+	using(t, func(string, Cmd) Result { return ok("No default controller available\n") })
+	if _, err := Controller(); err == nil || !strings.Contains(err.Error(), "no Bluetooth controller") {
+		t.Fatalf("%v", err)
+	}
+}
+
+func TestDevicesAskEachOneAndReportBatteryWhereGiven(t *testing.T) {
+	f := using(t, func(line string, c Cmd) Result {
+		switch line {
+		case "bluetoothctl devices Paired":
+			return ok("Device 80:99:E7:C2:29:DA WH-1000XM4\nDevice 2C:41:A1:E4:EC:86 Earmuffs\n")
+		case "bluetoothctl info 80:99:E7:C2:29:DA":
+			return ok(headphones(true))
+		}
+		return ok("Device 2C:41:A1:E4:EC:86 (public)\n\tName: Earmuffs\n\tPaired: yes\n\tConnected: no\n")
+	})
+	got, err := Devices("paired")
+	devices := got["devices"].([]Device)
+	if err != nil || got["count"] != 2 || !devices[0].Connected || devices[0].Battery == nil || *devices[0].Battery != 80 || devices[1].Battery != nil {
+		t.Fatalf("%+v %v", got, err)
+	}
+	if f.lines()[0] != "bluetoothctl devices Paired" {
+		t.Errorf("%v", f.lines())
+	}
+	if _, err := Devices("nearby"); err == nil {
+		t.Error("an unknown which")
+	}
+}
+
+func TestAnActThatFailsIsAnErrorWhateverTheExitStatus(t *testing.T) {
+	using(t, func(line string, c Cmd) Result {
+		return ok("Attempting to connect to 80:99:E7:C2:29:DA\nFailed to connect: org.bluez.Error.Failed br-connection-page-timeout\n")
+	})
+	if _, err := Act("connect", "80:99:E7:C2:29:DA"); err == nil || !strings.Contains(err.Error(), "page-timeout") {
+		t.Fatalf("%v", err)
+	}
+	using(t, func(string, Cmd) Result { return Result{Status: 1, Stdout: "Device 00:11:22:33:44:55 not available\n"} })
+	if _, err := Act("trust", "00:11:22:33:44:55"); err == nil || !strings.Contains(err.Error(), "not available") {
+		t.Fatalf("%v", err)
+	}
+}
+
+func TestConnectWaitsWithBluetoothctlsOwnTimeoutAndAnswersTheState(t *testing.T) {
+	f := using(t, func(line string, c Cmd) Result {
+		if strings.Contains(line, "connect") {
+			return ok("Attempting to connect\n[CHG] Device Connected: yes\nConnection successful\n")
+		}
+		return ok(headphones(true))
+	})
+	got, err := Act("connect", "80:99:E7:C2:29:DA")
+	if err != nil || !got["device"].(Device).Connected {
+		t.Fatalf("%v %v", got, err)
+	}
+	if f.lines()[0] != "bluetoothctl --timeout 15 connect 80:99:E7:C2:29:DA" || f.asked[0].Timeout != CallTimeout {
+		t.Errorf("%v", f.lines())
+	}
+}
+
+func TestAnActBluezRefusesTheAccountIsRetriedThroughSudo(t *testing.T) {
+	f := using(t, func(line string, c Cmd) Result {
+		if strings.HasPrefix(line, "sudo") {
+			return ok("Changing power off succeeded\n" + show)
+		}
+		return ok("Failed to set power off: org.freedesktop.DBus.Error.AccessDenied\n")
+	})
+	if _, err := Power(false); err != nil {
+		t.Fatal(err)
+	}
+	if l := f.lines(); l[0] != "bluetoothctl power off" || l[1] != "sudo -n bluetoothctl power off" {
+		t.Errorf("%v", l)
+	}
+}
+
+func TestScanIsBoundedAndAnswersUnpairedDevicesStrongestFirst(t *testing.T) {
+	f := using(t, func(line string, c Cmd) Result {
+		switch {
+		case strings.Contains(line, "scan on"):
+			return ok("Discovery started\n[NEW] Device AA:BB:CC:DD:EE:01 Speaker\n")
+		case line == "bluetoothctl devices":
+			return ok("Device 80:99:E7:C2:29:DA WH-1000XM4\nDevice AA:BB:CC:DD:EE:01 Speaker\nDevice AA:BB:CC:DD:EE:02 Phone\nDevice AA:BB:CC:DD:EE:03 Gone\n")
+		case strings.HasSuffix(line, "EE:01"):
+			return ok("Device AA:BB:CC:DD:EE:01\n\tName: Speaker\n\tPaired: no\n\tRSSI: 0xffffffc4 (-60)\n")
+		case strings.HasSuffix(line, "EE:02"):
+			return ok("Device AA:BB:CC:DD:EE:02\n\tName: Phone\n\tPaired: no\n\tRSSI: -40\n")
+		case strings.HasSuffix(line, "EE:03"):
+			return Result{Status: 1, Stdout: "Device AA:BB:CC:DD:EE:03 not available\n"}
+		}
+		return ok(headphones(false))
+	})
+	got, err := Scan(8)
+	found := got["found"].([]Device)
+	if err != nil || len(found) != 2 || found[0].Name != "Phone" || *found[1].RSSI != -60 {
+		t.Fatalf("%+v %v", got, err)
+	}
+	if f.lines()[0] != "bluetoothctl --timeout 8 scan on" || f.asked[0].Timeout.Seconds() != 12 {
+		t.Errorf("%v %v", f.lines()[0], f.asked[0].Timeout)
+	}
+}
+
+func TestPairUsesAnAgentThatConfirmsNothingAndThenTrusts(t *testing.T) {
+	f := using(t, func(line string, c Cmd) Result {
+		if strings.Contains(line, " pair ") {
+			return ok("Pairing successful\n")
+		}
+		return ok(headphones(false))
+	})
+	if _, err := Pair("80:99:e7:c2:29:da"); err != nil {
+		t.Fatal(err)
+	}
+	if l := f.lines(); l[0] != "bluetoothctl --agent NoInputNoOutput --timeout 15 pair 80:99:e7:c2:29:da" || l[1] != "bluetoothctl trust 80:99:e7:c2:29:da" {
+		t.Errorf("%v", l)
+	}
+}
+
+func TestAnAddressIsSixHexPairs(t *testing.T) {
+	for _, bad := range []string{"", "80:99:E7:C2:29", "80:99:E7:C2:29:DA; rm", "--help", "GG:99:E7:C2:29:DA"} {
+		if _, err := addressOf(map[string]any{"address": bad}); err == nil {
+			t.Errorf("%q accepted", bad)
+		}
+	}
+	if a, err := addressOf(map[string]any{"address": "80:99:e7:c2:29:da"}); err != nil || a != "80:99:E7:C2:29:DA" {
+		t.Errorf("%s %v", a, err)
+	}
+}

modules/bluetooth/cmd/bluetooth-tools/kit.go

@@ -0,0 +1,352 @@
+package main
+
+// kit.go is the same file in each of the workstations' tool bundles (fonts, docker-compose, snapd,
+// flatpak, cups, bluetooth, xclip, dmenu): how a tool runs a command, escalates, bounds what it
+// keeps, and names a failure. A module is built from its own directory, so the file is copied rather
+// than shared; a change to one copy is made to all eight.
+//
+// The rules it holds (novox/hq research 026/05, to-be 38 WP4):
+//   - the node's tool runtime runs as the operator account, not root (ADR 0175 §4); a command that
+//     needs root goes through `sudo -n`, never a prompt, and a refusal is named as such;
+//   - one command gets 20 s, below the runtime's 30 s call limit, and is ended with everything it
+//     started when it takes longer;
+//   - each stream is kept to 256 KiB, and the answer says when it was cut;
+//   - a failure is an error with what went wrong in it, never an empty answer.
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"strings"
+	"syscall"
+	"time"
+)
+
+// Bounds every command is held to.
+const (
+	CallTimeout = 20 * time.Second
+	MostOutput  = 256 << 10
+)
+
+// Cmd is one command a tool runs.
+type Cmd struct {
+	Name string
+	Args []string
+	// Stdin is written to the command's standard input when not empty.
+	Stdin string
+	// Env is added to this process's own environment.
+	Env []string
+	// Root says the command needs root: it is run through `sudo -n` when this process is not root.
+	Root bool
+	// Timeout replaces CallTimeout; only a background job (jobs.go) asks for longer.
+	Timeout time.Duration
+	// Detached is for a program that forks a child which outlives it, as xclip does to keep the
+	// selection: its streams go to files, because a pipe the child inherits would hold the call open
+	// until the child exits.
+	Detached bool
+}
+
+// Result is what a command did.
+type Result struct {
+	Stdout string `json:"stdout"`
+	Stderr string `json:"stderr"`
+	Status int    `json:"status"`
+	// Error is why it did not run to an answer: "not-found" when the program is not there,
+	// "timeout" when it was ended for taking too long, else the spawn error.
+	Error     string `json:"error,omitempty"`
+	Truncated bool   `json:"truncated,omitempty"`
+}
+
+// Runner runs a command. Tests replace it; nothing else does.
+type Runner func(Cmd) Result
+
+var (
+	run  Runner = execRun
+	euid        = os.Geteuid
+)
+
+// argv is the command as it is run: through sudo without a prompt when it needs root and this
+// process is not root.
+func argv(c Cmd) (string, []string) {
+	if c.Root && euid() != 0 {
+		return "sudo", append([]string{"-n", c.Name}, c.Args...)
+	}
+	return c.Name, c.Args
+}
+
+// bounded keeps the first MostOutput bytes written to it and notes that more came.
+type bounded struct {
+	b   bytes.Buffer
+	cut bool
+}
+
+func (w *bounded) Write(p []byte) (int, error) {
+	room := MostOutput - w.b.Len()
+	if room <= 0 {
+		w.cut = w.cut || len(p) > 0
+		return len(p), nil
+	}
+	if len(p) > room {
+		w.b.Write(p[:room])
+		w.cut = true
+		return len(p), nil
+	}
+	return w.b.Write(p)
+}
+
+func execRun(c Cmd) Result {
+	timeout := c.Timeout
+	if timeout <= 0 {
+		timeout = CallTimeout
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), timeout)
+	defer cancel()
+	name, args := argv(c)
+	cmd := exec.CommandContext(ctx, name, args...)
+	cmd.Env = append(append(os.Environ(), "LC_ALL=C"), c.Env...)
+	if !c.Detached {
+		// Its own process group, so that ending it on a timeout ends what it started too.
+		cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+		cmd.Cancel = func() error {
+			if cmd.Process != nil {
+				_ = syscall.Kill(-cmd.Process.Pid, syscall.SIGKILL)
+			}
+			return nil
+		}
+	}
+	cmd.WaitDelay = 2 * time.Second
+	if c.Stdin != "" {
+		cmd.Stdin = strings.NewReader(c.Stdin)
+	}
+	var out, errs bounded
+	var outFile, errFile *os.File
+	if c.Detached {
+		var err error
+		if outFile, err = os.CreateTemp("", "mesh-tool-out-*"); err != nil {
+			return Result{Status: 127, Error: err.Error()}
+		}
+		defer os.Remove(outFile.Name())
+		defer outFile.Close()
+		if errFile, err = os.CreateTemp("", "mesh-tool-err-*"); err != nil {
+			return Result{Status: 127, Error: err.Error()}
+		}
+		defer os.Remove(errFile.Name())
+		defer errFile.Close()
+		cmd.Stdout, cmd.Stderr = outFile, errFile
+	} else {
+		cmd.Stdout, cmd.Stderr = &out, &errs
+	}
+	err := cmd.Run()
+	if c.Detached {
+		for _, f := range []struct {
+			file *os.File
+			into *bounded
+		}{{outFile, &out}, {errFile, &errs}} {
+			if _, e := f.file.Seek(0, io.SeekStart); e == nil {
+				_, _ = io.Copy(f.into, f.file)
+			}
+		}
+	}
+	r := Result{Stdout: out.b.String(), Stderr: errs.b.String(), Truncated: out.cut || errs.cut}
+	var exit *exec.ExitError
+	switch {
+	case err == nil:
+	case ctx.Err() == context.DeadlineExceeded:
+		r.Status, r.Error = 124, "timeout"
+	case errors.Is(err, exec.ErrNotFound) || errors.Is(err, os.ErrNotExist):
+		r.Status, r.Error = 127, "not-found"
+	case errors.As(err, &exit):
+		r.Status = exit.ExitCode()
+	default:
+		r.Status, r.Error = 127, err.Error()
+	}
+	return r
+}
+
+// call runs a command and answers its result, or an error naming what went wrong.
+func call(c Cmd) (Result, error) {
+	r := run(c)
+	if r.Status == 0 && r.Error == "" {
+		return r, nil
+	}
+	return r, failure(c, r)
+}
+
+// failure names how a command failed: not installed, refused escalation, too slow, or its exit
+// status with the end of what it said.
+func failure(c Cmd, r Result) error {
+	program, _ := argv(c)
+	switch {
+	case r.Error == "not-found" && program == "sudo":
+		return fmt.Errorf("%s needs root, and sudo is not installed here for the runtime's account to escalate with", c.Name)
+	case r.Error == "not-found":
+		if hint, ok := providedBy[c.Name]; ok {
+			return fmt.Errorf("%s is not installed on this machine (%s)", c.Name, hint)
+		}
+		return fmt.Errorf("%s is not installed on this machine", c.Name)
+	case r.Error == "timeout":
+		limit := c.Timeout
+		if limit <= 0 {
+			limit = CallTimeout
+		}
+		return fmt.Errorf("%s gave no answer within %s and was ended", c.Name, limit)
+	case r.Error != "":
+		return fmt.Errorf("%s did not run: %s", c.Name, r.Error)
+	case program == "sudo" && strings.Contains(r.Stderr, "command not found"):
+		if hint, ok := providedBy[c.Name]; ok {
+			return fmt.Errorf("%s is not installed on this machine (%s)", c.Name, hint)
+		}
+		return fmt.Errorf("%s is not installed on this machine", c.Name)
+	case program == "sudo" && strings.HasPrefix(strings.TrimSpace(r.Stderr), "sudo:"):
+		return fmt.Errorf("%s needs root, and sudo -n refused the runtime's account: %s (the escalation is the sudo module's to declare)",
+			c.Name, firstLine(r.Stderr))
+	}
+	said := tail(strings.TrimSpace(r.Stderr), 2000)
+	if said == "" {
+		said = tail(strings.TrimSpace(r.Stdout), 2000)
+	}
+	if said == "" {
+		said = "and said nothing"
+	}
+	return fmt.Errorf("%s %s exited %d: %s", c.Name, strings.Join(c.Args, " "), r.Status, said)
+}
+
+func firstLine(s string) string {
+	s = strings.TrimSpace(s)
+	if i := strings.IndexByte(s, '\n'); i >= 0 {
+		return s[:i]
+	}
+	return s
+}
+
+func tail(s string, n int) string {
+	if len(s) <= n {
+		return s
+	}
+	return "…" + s[len(s)-n:]
+}
+
+// lines are a command's output lines, blank ones dropped.
+func lines(s string) []string {
+	out := []string{}
+	for _, l := range strings.Split(s, "\n") {
+		if strings.TrimSpace(l) != "" {
+			out = append(out, strings.TrimRight(l, "\r"))
+		}
+	}
+	return out
+}
+
+// Arguments, read the way a tool's JSON arguments arrive.
+
+func text(args map[string]any, key string) (string, error) {
+	v, ok := args[key]
+	if !ok || v == nil {
+		return "", fmt.Errorf("%s is required", key)
+	}
+	s, ok := v.(string)
+	if !ok {
+		return "", fmt.Errorf("%s must be a string", key)
+	}
+	if strings.TrimSpace(s) == "" {
+		return "", fmt.Errorf("%s must not be empty", key)
+	}
+	return s, nil
+}
+
+func optText(args map[string]any, key, def string) (string, error) {
+	v, ok := args[key]
+	if !ok || v == nil {
+		return def, nil
+	}
+	s, ok := v.(string)
+	if !ok {
+		return "", fmt.Errorf("%s must be a string", key)
+	}
+	if strings.TrimSpace(s) == "" {
+		return def, nil
+	}
+	return s, nil
+}
+
+// optWhole reads a whole number, defaulted, refused below least and held to most.
+func optWhole(args map[string]any, key string, def, least, most int) (int, error) {
+	v, ok := args[key]
+	if !ok || v == nil {
+		return def, nil
+	}
+	f, ok := v.(float64)
+	if !ok {
+		if i, isInt := v.(int); isInt {
+			f = float64(i)
+		} else {
+			return 0, fmt.Errorf("%s must be a number", key)
+		}
+	}
+	if f != float64(int(f)) {
+		return 0, fmt.Errorf("%s must be a whole number", key)
+	}
+	n := int(f)
+	if n < least {
+		return 0, fmt.Errorf("%s must be at least %d", key, least)
+	}
+	if n > most {
+		n = most
+	}
+	return n, nil
+}
+
+func optFlag(args map[string]any, key string, def bool) (bool, error) {
+	v, ok := args[key]
+	if !ok || v == nil {
+		return def, nil
+	}
+	b, ok := v.(bool)
+	if !ok {
+		return false, fmt.Errorf("%s must be true or false", key)
+	}
+	return b, nil
+}
+
+func optList(args map[string]any, key string) ([]string, error) {
+	v, ok := args[key]
+	if !ok || v == nil {
+		return nil, nil
+	}
+	items, ok := v.([]any)
+	if !ok {
+		return nil, fmt.Errorf("%s must be a list of strings", key)
+	}
+	out := make([]string, 0, len(items))
+	for _, it := range items {
+		s, ok := it.(string)
+		if !ok || strings.TrimSpace(s) == "" {
+			return nil, fmt.Errorf("%s must be a list of non-empty strings", key)
+		}
+		out = append(out, s)
+	}
+	return out, nil
+}
+
+// oneOf refuses a value outside a closed set.
+func oneOf(key, value string, allowed ...string) error {
+	for _, a := range allowed {
+		if value == a {
+			return nil
+		}
+	}
+	return fmt.Errorf("%s must be one of %s, not %q", key, strings.Join(allowed, ", "), value)
+}
+
+// plainName refuses a name that could be read as an option or carries a path or a space: package,
+// snap, application and printer names never do.
+func plainName(key, value string) error {
+	if strings.HasPrefix(value, "-") || strings.ContainsAny(value, " \t\n/\\") {
+		return fmt.Errorf("%s %q is not a plain name", key, value)
+	}
+	return nil
+}

modules/bluetooth/cmd/bluetooth-tools/kit_test.go

@@ -0,0 +1,147 @@
+package main
+
+// Tests of kit.go, the same in each workstation module.
+
+import (
+	"strings"
+	"testing"
+	"time"
+)
+
+// fake records the commands asked and answers each from a function of the command line.
+type fake struct {
+	asked  []Cmd
+	answer func(line string, c Cmd) Result
+}
+
+func (f *fake) runner() Runner {
+	return func(c Cmd) Result {
+		f.asked = append(f.asked, c)
+		name, args := argv(c)
+		line := strings.TrimSpace(name + " " + strings.Join(args, " "))
+		if f.answer == nil {
+			return Result{}
+		}
+		return f.answer(line, c)
+	}
+}
+
+func (f *fake) lines() []string {
+	out := []string{}
+	for _, c := range f.asked {
+		name, args := argv(c)
+		out = append(out, strings.TrimSpace(name+" "+strings.Join(args, " ")))
+	}
+	return out
+}
+
+// using installs a fake runner and a non-root uid for one test.
+func using(t *testing.T, answer func(line string, c Cmd) Result) *fake {
+	t.Helper()
+	f := &fake{answer: answer}
+	wasRun, wasUID := run, euid
+	run, euid = f.runner(), func() int { return 1000 }
+	t.Cleanup(func() { run, euid = wasRun, wasUID })
+	return f
+}
+
+func ok(stdout string) Result { return Result{Stdout: stdout} }
+
+func TestKitAnActThatNeedsRootGoesThroughSudoWithoutAPromptUnlessAlreadyRoot(t *testing.T) {
+	was := euid
+	defer func() { euid = was }()
+	euid = func() int { return 1000 }
+	if name, args := argv(Cmd{Name: "x", Args: []string{"a"}, Root: true}); name != "sudo" || strings.Join(args, " ") != "-n x a" {
+		t.Fatalf("not root: %s %v", name, args)
+	}
+	if name, _ := argv(Cmd{Name: "x"}); name != "x" {
+		t.Fatalf("a read is run as the account: %s", name)
+	}
+	euid = func() int { return 0 }
+	if name, _ := argv(Cmd{Name: "x", Root: true}); name != "x" {
+		t.Fatalf("as root no sudo: %s", name)
+	}
+}
+
+func TestKitAFailureIsNamedByHowItFailed(t *testing.T) {
+	was := euid
+	defer func() { euid = was }()
+	euid = func() int { return 1000 }
+	cases := []struct {
+		c    Cmd
+		r    Result
+		want string
+	}{
+		{Cmd{Name: "nothere"}, Result{Status: 127, Error: "not-found"}, "not installed"},
+		{Cmd{Name: "x", Root: true}, Result{Status: 127, Error: "not-found"}, "sudo is not installed"},
+		{Cmd{Name: "x", Root: true}, Result{Status: 1, Stderr: "sudo: a password is required\n"}, "sudo -n refused"},
+		{Cmd{Name: "x", Root: true}, Result{Status: 1, Stderr: "sudo: x: command not found\n"}, "x is not installed"},
+		{Cmd{Name: "x"}, Result{Status: 124, Error: "timeout"}, "within 20s"},
+		{Cmd{Name: "x", Args: []string{"y"}}, Result{Status: 3, Stderr: "boom\n"}, "x y exited 3: boom"},
+		{Cmd{Name: "x"}, Result{Status: 3}, "said nothing"},
+	}
+	for _, k := range cases {
+		err := failure(k.c, k.r)
+		if err == nil || !strings.Contains(err.Error(), k.want) {
+			t.Errorf("%+v: %v, want %q", k.r, err, k.want)
+		}
+	}
+}
+
+func TestKitOutputIsBoundedAndSaysSo(t *testing.T) {
+	var w bounded
+	big := strings.Repeat("a", MostOutput+10)
+	n, _ := w.Write([]byte(big))
+	if n != len(big) || w.b.Len() != MostOutput || !w.cut {
+		t.Fatalf("kept %d of %d, cut %v", w.b.Len(), len(big), w.cut)
+	}
+}
+
+func TestKitTheRealRunnerRunsEndsAndReportsAMissingProgram(t *testing.T) {
+	r := execRun(Cmd{Name: "sh", Args: []string{"-c", "echo out; echo err >&2; exit 3"}})
+	if r.Status != 3 || strings.TrimSpace(r.Stdout) != "out" || strings.TrimSpace(r.Stderr) != "err" {
+		t.Fatalf("%+v", r)
+	}
+	r = execRun(Cmd{Name: "sh", Args: []string{"-c", "sleep 5 & sleep 5"}, Timeout: 200 * time.Millisecond})
+	if r.Error != "timeout" {
+		t.Fatalf("a slow command: %+v", r)
+	}
+	r = execRun(Cmd{Name: "no-such-program-anywhere"})
+	if r.Error != "not-found" {
+		t.Fatalf("a missing program: %+v", r)
+	}
+	r = execRun(Cmd{Name: "cat", Stdin: "given"})
+	if r.Stdout != "given" {
+		t.Fatalf("stdin: %+v", r)
+	}
+	start := time.Now()
+	r = execRun(Cmd{Name: "sh", Args: []string{"-c", "echo kept; (sleep 3 &) ; exit 0"}, Detached: true})
+	if r.Status != 0 || strings.TrimSpace(r.Stdout) != "kept" || time.Since(start) > 2*time.Second {
+		t.Fatalf("a detached command returns when it exits, not when its child does: %+v after %s", r, time.Since(start))
+	}
+}
+
+func TestKitArgumentsAreReadStrictly(t *testing.T) {
+	args := map[string]any{"s": "x", "n": float64(5), "f": 1.5, "b": true, "l": []any{"a", "b"}}
+	if _, err := text(args, "missing"); err == nil {
+		t.Error("a missing required string")
+	}
+	if n, _ := optWhole(args, "n", 1, 1, 3); n != 3 {
+		t.Errorf("held to most: %d", n)
+	}
+	if _, err := optWhole(args, "n", 1, 6, 9); err == nil {
+		t.Error("below least")
+	}
+	if _, err := optWhole(args, "f", 1, 0, 9); err == nil {
+		t.Error("a fraction")
+	}
+	if l, _ := optList(args, "l"); len(l) != 2 {
+		t.Errorf("list: %v", l)
+	}
+	if b, _ := optFlag(args, "b", false); !b {
+		t.Error("flag")
+	}
+	if err := plainName("name", "--all"); err == nil {
+		t.Error("an option as a name")
+	}
+}

modules/bluetooth/cmd/bluetooth-tools/main.go

@@ -0,0 +1,135 @@
+// The bluetooth module's tools (novox/hq research 027/02, 026/05): the controller, the devices with
+// their state and battery, scanning, and pairing, connecting, trusting and forgetting a device. A Go
+// bundle the node's runtime launches over stdio (ADR 0188, ADR 0193); it runs as the operator
+// account, and speaks to bluez through bluetoothctl.
+package main
+
+import (
+	"fmt"
+	"os"
+
+	stdio "git.novox.be/novox/mesh-sdk/go"
+)
+
+var providedBy = map[string]string{
+	"bluetoothctl": "the bluez-utils package, which this module installs",
+}
+
+func main() {
+	if err := stdio.Serve("", tools()); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
+
+var addressArg = map[string]any{"type": "string", "description": "the device's address, such as 80:99:E7:C2:29:DA, as bluetooth_devices answers it"}
+
+func withAddress(f func(string) (any, error)) func(map[string]any) (any, error) {
+	return func(args map[string]any) (any, error) {
+		a, err := addressOf(args)
+		if err != nil {
+			return nil, err
+		}
+		return f(a)
+	}
+}
+
+func tools() []stdio.Tool {
+	return []stdio.Tool{
+		{
+			Name:        "bluetooth_controller",
+			Description: "The machine's Bluetooth controller: address, name, powered, discoverable, pairable, discovering. (r)",
+			Input:       map[string]any{},
+			Run:         func(map[string]any) (any, error) { return Controller() },
+		},
+		{
+			Name:        "bluetooth_power",
+			Description: "Whether the controller is powered; with on, switch it on or off. (r/a)",
+			Input:       map[string]any{"on": map[string]any{"type": "boolean", "description": "power the controller on (true) or off (false)"}},
+			Run: func(args map[string]any) (any, error) {
+				if _, given := args["on"]; !given {
+					c, err := Controller()
+					if err != nil {
+						return nil, err
+					}
+					return map[string]any{"powered": c.Powered}, nil
+				}
+				on, err := optFlag(args, "on", true)
+				if err != nil {
+					return nil, err
+				}
+				return Power(on)
+			},
+		},
+		{
+			Name: "bluetooth_devices",
+			Description: "The devices bluez knows: every one, or only the paired, connected or trusted. Each with its " +
+				"name, kind, paired, bonded, trusted, blocked, connected, and its battery where the device reports it. (r)",
+			Input: map[string]any{"which": map[string]any{"type": "string", "enum": []string{"all", "paired", "connected", "trusted"}, "description": "which devices (default all)"}},
+			Run: func(args map[string]any) (any, error) {
+				which, err := optText(args, "which", "all")
+				if err != nil {
+					return nil, err
+				}
+				return Devices(which)
+			},
+		},
+		{
+			Name: "bluetooth_scan",
+			Description: "Discover devices nearby for a few seconds (default 8, at most 15), and answer the ones not " +
+				"paired, with their signal strength. (r)",
+			Input: map[string]any{"seconds": map[string]any{"type": "integer", "description": "how long to scan (default 8, at most 15)"}},
+			Run: func(args map[string]any) (any, error) {
+				s, err := optWhole(args, "seconds", 8, 1, 15)
+				if err != nil {
+					return nil, err
+				}
+				return Scan(s)
+			},
+		},
+		{
+			Name:        "bluetooth_connect",
+			Description: "Connect a paired device, such as headphones. Answers its state afterwards. (a)",
+			Input:       map[string]any{"address": addressArg},
+			Run:         withAddress(func(a string) (any, error) { return Act("connect", a) }),
+		},
+		{
+			Name:        "bluetooth_disconnect",
+			Description: "Disconnect a device. (a)",
+			Input:       map[string]any{"address": addressArg},
+			Run:         withAddress(func(a string) (any, error) { return Act("disconnect", a) }),
+		},
+		{
+			Name:        "bluetooth_trust",
+			Description: "Trust a device, so it may connect by itself; or with trusted false, stop trusting it. (a)",
+			Input:       map[string]any{"address": addressArg, "trusted": map[string]any{"type": "boolean", "description": "trust (default) or untrust"}},
+			Run: func(args map[string]any) (any, error) {
+				a, err := addressOf(args)
+				if err != nil {
+					return nil, err
+				}
+				trusted, err := optFlag(args, "trusted", true)
+				if err != nil {
+					return nil, err
+				}
+				if trusted {
+					return Act("trust", a)
+				}
+				return Act("untrust", a)
+			},
+		},
+		{
+			Name: "bluetooth_pair",
+			Description: "Pair a device found by a scan, and trust it. Works for a device that needs no code to be " +
+				"confirmed, such as headphones; one that shows a code is paired from the desktop. (a)",
+			Input: map[string]any{"address": addressArg},
+			Run:   withAddress(func(a string) (any, error) { return Pair(a) }),
+		},
+		{
+			Name:        "bluetooth_remove",
+			Description: "Forget a device: unpair it and drop what bluez knows of it. (a)",
+			Input:       map[string]any{"address": addressArg},
+			Run:         withAddress(func(a string) (any, error) { return Act("remove", a) }),
+		},
+	}
+}

modules/bluetooth/cmd/bluetooth-tools/manifest_kit_test.go

@@ -0,0 +1,107 @@
+package main
+
+// manifest_kit_test.go is the same file in each workstation module: it reads the module's
+// definition so the module's own tests can hold it to what it says.
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"testing"
+)
+
+type manifest struct {
+	Module       string           `json:"module"`
+	Capabilities []string         `json:"capabilities"`
+	Claims       []any            `json:"claims"`
+	Seats        []any            `json:"seats"`
+	Tools        []string         `json:"tools"`
+	Resources    []map[string]any `json:"resources"`
+	Build        struct {
+		Artifacts []map[string]any `json:"artifacts"`
+	} `json:"build"`
+}
+
+func readManifest(t *testing.T) manifest {
+	t.Helper()
+	raw, err := os.ReadFile(filepath.Join("..", "..", "module.json"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	var m manifest
+	if err := json.Unmarshal(raw, &m); err != nil {
+		t.Fatalf("module.json: %v", err)
+	}
+	return m
+}
+
+func (m manifest) resource(id string) map[string]any {
+	for _, r := range m.Resources {
+		if r["id"] == id {
+			return r
+		}
+	}
+	return nil
+}
+
+// packages are the packages the module installs, sorted.
+func (m manifest) packages() []string {
+	out := []string{}
+	for _, r := range m.Resources {
+		if r["type"] == "package" && r["absent"] != true {
+			out = append(out, r["package"].(string))
+		}
+	}
+	sort.Strings(out)
+	return out
+}
+
+// services are the units the module declares, by unit name.
+func (m manifest) services() map[string]map[string]any {
+	out := map[string]map[string]any{}
+	for _, r := range m.Resources {
+		if r["type"] == "service" {
+			out[r["unit"].(string)] = r
+		}
+	}
+	return out
+}
+
+// holdsTheBundle holds the manifest to the Go bundle this directory builds: every tool registered
+// is listed and nothing else, each named <prefix>_…, and the artifact builds this command.
+func holdsTheBundle(t *testing.T, m manifest, prefix string) {
+	t.Helper()
+	registered := []string{}
+	for _, tool := range tools() {
+		registered = append(registered, tool.Name)
+		if !strings.HasPrefix(tool.Name, prefix+"_") {
+			t.Errorf("tool %s is not named %s_…", tool.Name, prefix)
+		}
+		if tool.Description == "" || tool.Run == nil || tool.Input == nil {
+			t.Errorf("tool %s is not described, runnable and given an input schema", tool.Name)
+		}
+	}
+	if strings.Join(registered, ",") != strings.Join(m.Tools, ",") {
+		t.Errorf("registered %v, listed %v", registered, m.Tools)
+	}
+	if len(m.Build.Artifacts) != 1 {
+		t.Fatalf("one artifact, got %d", len(m.Build.Artifacts))
+	}
+	cwd, _ := os.Getwd()
+	binary := filepath.Base(cwd)
+	a := m.Build.Artifacts[0]
+	want := map[string]any{"kind": "bundle", "language": "go", "system": "arch", "from": "cmd/" + binary, "binary": binary}
+	for k, v := range want {
+		if a[k] != v {
+			t.Errorf("artifact %s = %v, want %v", k, a[k], v)
+		}
+	}
+	if loads, _ := a["loads"].([]any); len(loads) != 1 || loads[0] != binary {
+		t.Errorf("artifact loads %v, want [%s]", a["loads"], binary)
+	}
+	if m.Claims != nil || m.Seats != nil {
+		t.Errorf("claims %v, seats %v: this module holds no seat", m.Claims, m.Seats)
+	}
+}

modules/bluetooth/go.mod

@@ -0,0 +1,5 @@
+module bluetooth
+
+go 1.22
+
+require git.novox.be/novox/mesh-sdk/go v0.1.6

modules/bluetooth/go.sum

@@ -0,0 +1,2 @@
+git.novox.be/novox/mesh-sdk/go v0.1.6 h1:9qzdYONYbJdWcu6sxQcq9v1LI0JxcfkiKYkMUzJSkVQ=
+git.novox.be/novox/mesh-sdk/go v0.1.6/go.mod h1:GFuZUElBZ9A++mxgIKo97aXXo+kV0uJ/UkbhQPPIbrY=

modules/bluetooth/module.json

@@ -0,0 +1,53 @@
+{
+  "module": "bluetooth",
+  "version": "1",
+  "capabilities": [
+    "package-manager",
+    "service-manager"
+  ],
+  "tools": [
+    "bluetooth_controller",
+    "bluetooth_power",
+    "bluetooth_devices",
+    "bluetooth_scan",
+    "bluetooth_connect",
+    "bluetooth_disconnect",
+    "bluetooth_trust",
+    "bluetooth_pair",
+    "bluetooth_remove"
+  ],
+  "resources": [
+    {
+      "id": "stack",
+      "type": "package",
+      "package": "bluez"
+    },
+    {
+      "id": "utilities",
+      "type": "package",
+      "package": "bluez-utils"
+    },
+    {
+      "id": "daemon",
+      "type": "service",
+      "unit": "bluetooth.service",
+      "state": "running",
+      "boot": "enabled"
+    }
+  ],
+  "build": {
+    "artifacts": [
+      {
+        "name": "tools",
+        "kind": "bundle",
+        "language": "go",
+        "system": "arch",
+        "from": "cmd/bluetooth-tools",
+        "binary": "bluetooth-tools",
+        "loads": [
+          "bluetooth-tools"
+        ]
+      }
+    ]
+  }
+}

modules/claude-licence-manager/cmd/claude-licence-manager/manager.go

@@ -198,6 +198,12 @@ func (m *Manager) Consider(ctx context.Context, reports []Holdings) ([]string, e
 		accounts = append(accounts, a)
 	}
 	sort.Strings(accounts)
+	// A node reporting an account the manager already holds, and bound to nothing, is bound to it
+	// (ADR 0206 §7) — whenever its report arrives, not only when the licence is adopted: a node whose own
+	// login is older than the one adopted is never a candidate, and would otherwise never be bound.
+	if err := m.bindReporters(ctx, reports); err != nil {
+		return nil, err
+	}
 	var adopted []string
 	for _, account := range accounts {
 		list := byAccount[account]
@@ -225,6 +231,38 @@ func (m *Manager) Consider(ctx context.Context, reports []Holdings) ([]string, e
 	return adopted, nil
 }
 
+// bindReporters binds each reporting node that is bound to nothing to the licence its account already has.
+func (m *Manager) bindReporters(ctx context.Context, reports []Holdings) error {
+	for _, rep := range reports {
+		if rep.Identity == nil || rep.Identity.AccountUUID == "" {
+			continue
+		}
+		if b, err := m.Store.Binding(ctx, rep.Node); err != nil || b != nil {
+			if err != nil {
+				return err
+			}
+			continue
+		}
+		l, err := m.Store.LicenceForAccount(ctx, rep.Identity.AccountUUID)
+		if err != nil {
+			return err
+		}
+		if l == nil {
+			continue
+		}
+		b, err := m.Store.Bind(ctx, rep.Node, l.Name)
+		if err != nil {
+			return err
+		}
+		_ = m.Store.Audit(ctx, "bound", map[string]any{"consumer": rep.Node, "licence": l.Name, "by": "its account's report"})
+		if err := m.PutBinding(ctx, rep.Node, BindingState{Licence: l.Name, Kind: l.Kind, Generation: b.Generation}); err != nil {
+			return err
+		}
+		m.Log("bound %s to %s, the licence its account already has", rep.Node, l.Name)
+	}
+	return nil
+}
+
 func (m *Manager) adoptOne(ctx context.Context, c Candidate, reports []Holdings) (string, error) {
 	answer, err := m.AskGrant(ctx, c.Node, m.Keys.PublicKey)
 	if err != nil {

modules/claude-licence-manager/cmd/claude-licence-manager/manager_test.go

@@ -336,3 +336,24 @@ func TestAReportIsReadAsTheAgentModuleWritesIt(t *testing.T) {
 		t.Fatalf("the report's time does not parse: %v", err)
 	}
 }
+
+// A node whose report arrives after its account was adopted — with an older login, so never a candidate —
+// is still bound to that account's licence, once.
+func TestANodeReportingAnAdoptedAccountLaterIsBoundToIt(t *testing.T) {
+	mm := newMesh(t)
+	ctx := context.Background()
+	_, _ = mm.m.Consider(ctx, []Holdings{mm.login("novox", "rt-new", true, t0)})
+	late := mm.login("laptop", "rt-older", true, t0.Add(-24*time.Hour))
+	_, _ = mm.m.Consider(ctx, []Holdings{late})
+	if mm.state["laptop"].Licence != licence1 {
+		t.Fatalf("a node reporting the adopted account later was not bound: %v", mm.state)
+	}
+	if strings.Contains(strings.Join(mm.vendor.exchanged, ","), "rt-older") {
+		t.Fatal("the older login was exchanged")
+	}
+	g := mm.state["laptop"].Generation
+	_, _ = mm.m.Consider(ctx, []Holdings{late})
+	if mm.state["laptop"].Generation != g {
+		t.Fatal("a node already bound was bound again")
+	}
+}

modules/clipmenu/README.md

@@ -0,0 +1,69 @@
+# clipmenu
+
+The clipboard manager as a module (novox/hq ADR 0208, research 026/04).
+
+- Installs `clipmenu` from the official repositories. It brings `clipnotify`, `xsel`, `xdotool` and
+  `dmenu` as its own dependencies.
+- Claims the mesh's `node-clipboard` seat and serves its verbs `history` and `copy`. Requires
+  `x11-display` on its own machine.
+- **Declares `rofi-greenclip` absent** (ADR 0180). This module replaces it.
+- Starts `clipmenud` **once per session**, from the session's start (the `xinitrc` slot `normal`).
+  It is not a user unit as well. Its packaged unit needs user-scoped units (mesh-host #72, not
+  merged), and the session start alone is one starter.
+- Binds `$mod+period` to `clipmenu`, as its own i3 drop-in (`50-clipmenu.conf`). clipmenu shows the
+  history through `dmenu`, the seat command of `node-launcher`, so it looks like every other menu.
+- Its settings are environment contributions (ADR 0203), read by the daemon, the menu and the tools
+  alike:
+  - `CM_SELECTIONS=clipboard`: what was copied, not every highlighted word. The found greenclip did
+    the same.
+  - `CM_MAX_CLIPS=500`: how many clips are kept.
+  - `CM_HISTLENGTH=15`: how many lines the menu shows.
+
+## Tools
+
+| tool | does |
+|---|---|
+| `node-clipboard.history` | the history, newest first, each entry once with its id, first line, time, size and text (cut) |
+| `node-clipboard.copy` | put text on the clipboard; it enters the history like any copy |
+| `clipmenu_paste` | what the clipboard holds now |
+| `clipmenu_clear` | forget the history; the daemon's locks stay |
+| `clipmenu_delete` | forget one entry, by id or first line |
+
+The history is read from clipmenu's own store, in the account's runtime directory, under clipmenu's
+own lock, so a copy arriving meanwhile is neither lost nor half-written. `copy` hands the text to an
+owner (`xsel`) under the account's service manager. As a child of the tools runtime, the clipboard
+would empty whenever the runtime restarted.
+
+## What it improves on what was found
+
+- **No AUR package.** greenclip came from the user repository. clipmenu is in the official one.
+- **Started once.** greenclip was started by the window manager on both workstations, and on the
+  desktop by an enabled user unit as well.
+- **No absolute home path** in any configuration. greenclip's named one.
+- **The history does not outlive a reboot.** greenclip kept it in `~/.cache`, so every password ever
+  copied stayed on disk. clipmenu keeps it in the runtime directory, which is memory.
+- **One menu.** The history appears in the launcher's own menu, through the seat's `dmenu` command,
+  instead of a theme from a cloned theme repository.
+
+## What it leaves as found
+
+- `~/.config/greenclip.toml` and greenclip's history, `~/.cache/greenclip.history`.
+- On the desktop: greenclip's enabled user unit link
+  (`~/.config/systemd/user/default.target.wants/greenclip.service`). It dangles once the package is
+  gone.
+
+## Migration (ADR 0182)
+
+1. After the first push, delete `~/.config/greenclip.toml` and `~/.cache/greenclip.history`.
+2. On the desktop: `systemctl --user disable greenclip.service`, before the push if you can. The
+   package's removal takes the unit file with it.
+3. Until the `i3` module carries the main configuration, the found `exec --no-startup-id greenclip
+   daemon` and `$mod+period` lines stay in `~/.config/i3/config`. i3 reports `$mod+period` as bound
+   twice. The `i3` module's configuration carries neither.
+
+## Blockers
+
+- `node-clipboard`, `x11-display` and the `xinitrc` slot are ADR 0208's. Until the controller knows
+  them, `mctl` reads them as unknown.
+- `CM_*` reach the session through `node-env` (ADR 0203), so the account's environment module must
+  be assigned too. Without it clipmenu runs on its defaults: both selections, 1000 clips, 8 lines.

modules/clipmenu/cmd/clipmenu-tools/args.go

@@ -0,0 +1,97 @@
+// Reading a tool's arguments: JSON numbers arrive as float64, and a missing argument is its default.
+// The same in every desktop module that carries it.
+package main
+
+import (
+	"fmt"
+	"math"
+	"strings"
+	"time"
+)
+
+// text is a string argument, trimmed; required says an empty one is refused.
+func text(args map[string]any, key string, required bool) (string, error) {
+	v, present := args[key]
+	if !present || v == nil {
+		if required {
+			return "", fmt.Errorf("%s is required", key)
+		}
+		return "", nil
+	}
+	s, ok := v.(string)
+	if !ok {
+		return "", fmt.Errorf("%s is a string, not %T", key, v)
+	}
+	s = strings.TrimSpace(s)
+	if s == "" && required {
+		return "", fmt.Errorf("%s is required", key)
+	}
+	return s, nil
+}
+
+// whole is a whole-number argument within [least, most], or def when absent.
+func whole(args map[string]any, key string, def, least, most int) (int, error) {
+	v, present := args[key]
+	if !present || v == nil {
+		return def, nil
+	}
+	f, ok := v.(float64)
+	if !ok {
+		if i, isInt := v.(int); isInt {
+			f = float64(i)
+		} else {
+			return 0, fmt.Errorf("%s is a number, not %T", key, v)
+		}
+	}
+	if f != math.Trunc(f) {
+		return 0, fmt.Errorf("%s is a whole number, not %v", key, f)
+	}
+	n := int(f)
+	if n < least || n > most {
+		return 0, fmt.Errorf("%s is %d; it is between %d and %d", key, n, least, most)
+	}
+	return n, nil
+}
+
+// flag is a boolean argument, or def when absent.
+func flag(args map[string]any, key string, def bool) (bool, error) {
+	v, present := args[key]
+	if !present || v == nil {
+		return def, nil
+	}
+	b, ok := v.(bool)
+	if !ok {
+		return false, fmt.Errorf("%s is true or false, not %T", key, v)
+	}
+	return b, nil
+}
+
+// texts is a list-of-strings argument.
+func texts(args map[string]any, key string) ([]string, error) {
+	v, present := args[key]
+	if !present || v == nil {
+		return nil, nil
+	}
+	list, ok := v.([]any)
+	if !ok {
+		if ss, isStrings := v.([]string); isStrings {
+			return ss, nil
+		}
+		return nil, fmt.Errorf("%s is a list of strings, not %T", key, v)
+	}
+	out := make([]string, 0, len(list))
+	for i, item := range list {
+		s, ok := item.(string)
+		if !ok {
+			return nil, fmt.Errorf("%s[%d] is a string, not %T", key, i, item)
+		}
+		out = append(out, s)
+	}
+	return out, nil
+}
+
+// seconds is a timeout argument in seconds, defaulted and bounded below the runtime's call limit.
+func seconds(args map[string]any, key string, def, most int) (time.Duration, error) {
+	n, err := whole(args, key, def, 1, most)
+	return time.Duration(n) * time.Second, err
+}

modules/clipmenu/cmd/clipmenu-tools/clipboard.go

@@ -0,0 +1,348 @@
+package main
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"os"
+	"os/user"
+	"path/filepath"
+	"sort"
+	"strconv"
+	"strings"
+	"syscall"
+	"time"
+)
+
+const (
+	mostCopy  = 1 << 20
+	mostPaste = 64 << 10
+	// majorVersion is clipmenu's store layout: <dir>/clipmenu.<major>.<user>/.
+	majorVersion = 6
+)
+
+// account is the user clipmenu's store is named for.
+func account() string {
+	for _, k := range []string{"USER", "MESH_OPERATOR_ACCOUNT", "LOGNAME"} {
+		if v := strings.TrimSpace(os.Getenv(k)); v != "" {
+			return v
+		}
+	}
+	if u, err := user.Current(); err == nil {
+		return u.Username
+	}
+	return ""
+}
+
+// storeDir is where clipmenud keeps the history: CM_DIR, else the account's runtime directory.
+func storeDir(s Session) (string, error) {
+	base := os.Getenv("CM_DIR")
+	if base == "" {
+		base = s.RuntimeDir
+	}
+	if base == "" {
+		return "", fmt.Errorf("%w: the account's runtime directory, where the clipboard history lives, is missing (the account is not logged in)", ErrNoBus)
+	}
+	return filepath.Join(base, fmt.Sprintf("clipmenu.%d.%s", majorVersion, account())), nil
+}
+
+// cksum is POSIX cksum(1) of data: clipmenu names each entry's file by the cksum of its first line
+// followed by a newline, as "<crc> <length>".
+func cksum(data []byte) string {
+	var crc uint32
+	step := func(b byte) {
+		crc ^= uint32(b) << 24
+		for i := 0; i < 8; i++ {
+			if crc&0x80000000 != 0 {
+				crc = crc<<1 ^ 0x04C11DB7
+			} else {
+				crc <<= 1
+			}
+		}
+	}
+	for _, b := range data {
+		step(b)
+	}
+	for n := len(data); n != 0; n >>= 8 {
+		step(byte(n))
+	}
+	return fmt.Sprintf("%d %d", ^crc, len(data))
+}
+
+func entryID(line string) string { return cksum([]byte(line + "\n")) }
+
+// Entry is one clip in the history.
+type Entry struct {
+	ID        string `json:"id"`
+	Line      string `json:"line"`
+	At        string `json:"at"`
+	Bytes     int    `json:"bytes"`
+	Text      string `json:"text,omitempty"`
+	Truncated bool   `json:"truncated,omitempty"`
+	at        int64
+}
+
+// HistoryResult is what node-clipboard.history answers.
+type HistoryResult struct {
+	Collecting bool    `json:"collecting"`
+	Store      string  `json:"store"`
+	Total      int     `json:"total"`
+	Entries    []Entry `json:"entries"`
+}
+
+// readStore reads clipmenu's line cache: one "<nanoseconds> <first line>" per copy, oldest first, a
+// line repeated when the same thing was copied again. The newest copy of each line wins.
+func readStore(dir string) ([]Entry, error) {
+	f, err := os.Open(filepath.Join(dir, "line_cache"))
+	if errors.Is(err, os.ErrNotExist) {
+		return []Entry{}, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	latest := map[string]int64{}
+	scan := bufio.NewScanner(f)
+	scan.Buffer(make([]byte, 64<<10), 1<<20)
+	for scan.Scan() {
+		stamp, line, ok := strings.Cut(scan.Text(), " ")
+		if !ok {
+			continue
+		}
+		ns, err := strconv.ParseInt(stamp, 10, 64)
+		if err != nil {
+			continue
+		}
+		if ns >= latest[line] {
+			latest[line] = ns
+		}
+	}
+	out := make([]Entry, 0, len(latest))
+	for line, ns := range latest {
+		out = append(out, Entry{ID: entryID(line), Line: line, at: ns, At: time.Unix(0, ns).Format(time.RFC3339)})
+	}
+	sort.Slice(out, func(i, j int) bool { return out[i].at > out[j].at })
+	return out, scan.Err()
+}
+
+// History is the clipboard's history, newest first.
+func History(limit, maxBytes int) (HistoryResult, error) {
+	dir, err := storeDir(findEnvironment())
+	if err != nil {
+		return HistoryResult{}, err
+	}
+	entries, err := readStore(dir)
+	if err != nil {
+		return HistoryResult{}, err
+	}
+	out := HistoryResult{Collecting: len(processesOf("clipmenud")) > 0, Store: dir, Total: len(entries), Entries: []Entry{}}
+	for i, e := range entries {
+		if i == limit {
+			break
+		}
+		if info, err := os.Stat(filepath.Join(dir, e.ID)); err == nil {
+			e.Bytes = int(info.Size())
+			if maxBytes > 0 {
+				raw, _ := os.ReadFile(filepath.Join(dir, e.ID))
+				if len(raw) > maxBytes {
+					raw, e.Truncated = raw[:maxBytes], true
+				}
+				e.Text = string(raw)
+			}
+		}
+		out.Entries = append(out.Entries, e)
+	}
+	return out, nil
+}
+
+// CopyResult is what node-clipboard.copy answers.
+type CopyResult struct {
+	Bytes int    `json:"bytes"`
+	Unit  string `json:"unit"`
+}
+
+// Copy puts text on the clipboard. The clipboard is owned by a process until another copies, so the
+// owner (xsel) runs under the account's service manager, not as a child of this tool.
+func Copy(text string) (CopyResult, error) {
+	if len(text) == 0 {
+		return CopyResult{}, errors.New("text is empty; to empty the clipboard's history, clipmenu_clear")
+	}
+	if len(text) > mostCopy {
+		return CopyResult{}, fmt.Errorf("%d bytes; the clipboard takes at most %d here", len(text), mostCopy)
+	}
+	s, err := findSession()
+	if err != nil {
+		return CopyResult{}, err
+	}
+	if s.RuntimeDir == "" {
+		return CopyResult{}, fmt.Errorf("%w: no runtime directory to hand the text over in", ErrNoBus)
+	}
+	// Handed over in a file only the account can read, which the owner reads and removes.
+	f, err := os.CreateTemp(s.RuntimeDir, "clipmenu-copy-")
+	if err != nil {
+		return CopyResult{}, err
+	}
+	if _, err := f.WriteString(text); err != nil {
+		f.Close()
+		os.Remove(f.Name())
+		return CopyResult{}, err
+	}
+	f.Close()
+	unit := uniqueUnit("clipmenu-copy")
+	script := `xsel --nodetach --input --clipboard < "$0" & sleep 1; rm -f "$0"; wait`
+	if err := s.detach(unit, "/bin/sh", "-c", script, f.Name()); err != nil {
+		os.Remove(f.Name())
+		return CopyResult{}, err
+	}
+	return CopyResult{Bytes: len(text), Unit: unit + ".service"}, nil
+}
+
+// PasteResult is what clipmenu_paste answers.
+type PasteResult struct {
+	Text      string `json:"text"`
+	Bytes     int    `json:"bytes"`
+	Truncated bool   `json:"truncated,omitempty"`
+}
+
+// Paste reads the clipboard now.
+func Paste() (PasteResult, error) {
+	s, err := findSession()
+	if err != nil {
+		return PasteResult{}, err
+	}
+	r, err := s.run(5*time.Second, "", "xsel", "--output", "--clipboard")
+	if err != nil {
+		return PasteResult{}, err
+	}
+	if r.Code != 0 {
+		return PasteResult{}, fmt.Errorf("xsel: %s", strings.TrimSpace(r.Stderr))
+	}
+	out := PasteResult{Text: r.Stdout, Bytes: len(r.Stdout), Truncated: r.Truncated}
+	if len(out.Text) > mostPaste {
+		out.Text, out.Truncated = out.Text[:mostPaste], true
+	}
+	return out, nil
+}
+
+// ChangeResult is what clear and delete answer.
+type ChangeResult struct {
+	Removed   int `json:"removed"`
+	Remaining int `json:"remaining"`
+}
+
+// withStoreLock holds clipmenu's own lock on its store, the one clipmenud and clipdel take, while
+// change runs, so a copy arriving meanwhile is neither lost nor half-written.
+func withStoreLock(dir string, change func() error) error {
+	lock, err := os.OpenFile(filepath.Join(dir, "lock"), os.O_CREATE|os.O_WRONLY, 0o600)
+	if err != nil {
+		return err
+	}
+	defer lock.Close()
+	deadline := time.Now().Add(2 * time.Second)
+	for {
+		err := syscall.Flock(int(lock.Fd()), syscall.LOCK_EX|syscall.LOCK_NB)
+		if err == nil {
+			break
+		}
+		if time.Now().After(deadline) {
+			return fmt.Errorf("the clipboard store is locked by clipmenud and did not come free within 2s")
+		}
+		time.Sleep(50 * time.Millisecond)
+	}
+	defer syscall.Flock(int(lock.Fd()), syscall.LOCK_UN)
+	return change()
+}
+
+func storeOf() (string, error) {
+	dir, err := storeDir(findEnvironment())
+	if err != nil {
+		return "", err
+	}
+	if _, err := os.Stat(dir); errors.Is(err, os.ErrNotExist) {
+		return "", fmt.Errorf("there is no clipboard history at %s: clipmenud has not run in this login", dir)
+	}
+	return dir, nil
+}
+
+// Clear forgets every entry and its text, keeping the store and its locks (clipdel's own clear
+// removes the directory, the daemon's lock with it).
+func Clear() (ChangeResult, error) {
+	dir, err := storeOf()
+	if err != nil {
+		return ChangeResult{}, err
+	}
+	var out ChangeResult
+	err = withStoreLock(dir, func() error {
+		entries, err := readStore(dir)
+		if err != nil {
+			return err
+		}
+		out.Removed = len(entries)
+		files, err := os.ReadDir(dir)
+		if err != nil {
+			return err
+		}
+		for _, f := range files {
+			switch f.Name() {
+			case "lock", "session_lock", "line_cache":
+				continue
+			}
+			if f.Type().IsRegular() {
+				if err := os.Remove(filepath.Join(dir, f.Name())); err != nil {
+					return err
+				}
+			}
+		}
+		return os.WriteFile(filepath.Join(dir, "line_cache"), nil, 0o600)
+	})
+	return out, err
+}
+
+// Delete forgets one entry, by id or by its first line.
+func Delete(id, line string) (ChangeResult, error) {
+	if (id == "") == (line == "") {
+		return ChangeResult{}, errors.New("give the entry's id or its line, one of the two")
+	}
+	dir, err := storeOf()
+	if err != nil {
+		return ChangeResult{}, err
+	}
+	var out ChangeResult
+	err = withStoreLock(dir, func() error {
+		raw, err := os.ReadFile(filepath.Join(dir, "line_cache"))
+		if err != nil && !errors.Is(err, os.ErrNotExist) {
+			return err
+		}
+		var kept []string
+		for _, l := range strings.Split(strings.TrimRight(string(raw), "\n"), "\n") {
+			if l == "" {
+				continue
+			}
+			_, text, _ := strings.Cut(l, " ")
+			if text == line || (id != "" && entryID(text) == id) {
+				out.Removed++
+				_ = os.Remove(filepath.Join(dir, entryID(text)))
+				continue
+			}
+			kept = append(kept, l)
+		}
+		if out.Removed == 0 {
+			return fmt.Errorf("no entry %s%s in the clipboard history", id, line)
+		}
+		content := strings.Join(kept, "\n")
+		if content != "" {
+			content += "\n"
+		}
+		tmp := filepath.Join(dir, ".line_cache.mesh")
+		if err := os.WriteFile(tmp, []byte(content), 0o600); err != nil {
+			return err
+		}
+		return os.Rename(tmp, filepath.Join(dir, "line_cache"))
+	})
+	if err != nil {
+		return ChangeResult{}, err
+	}
+	entries, _ := readStore(dir)
+	out.Remaining = len(entries)
+	return out, nil
+}

modules/clipmenu/cmd/clipmenu-tools/clipboard_test.go

@@ -0,0 +1,163 @@
+package main
+
+import (
+	"errors"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"testing"
+)
+
+const nobody = 4194400
+
+func TestEntryIdsAreWhatClipmenuNamesItsFiles(t *testing.T) {
+	for _, line := range []string{"hello", "", "two words (3 lines)", "ünïcode ✓", strings.Repeat("x", 300)} {
+		out, err := exec.Command("bash", "-c", `cksum <<< "$1"`, "_", line).Output()
+		if err != nil {
+			t.Skip("bash or cksum is missing here")
+		}
+		if got, want := entryID(line), strings.TrimSpace(string(out)); got != want {
+			t.Errorf("%q: %s, cksum says %s", line, got, want)
+		}
+	}
+}
+
+// store makes clipmenu's store as clipmenud leaves it, for the account the tools run as.
+func store(t *testing.T, clips map[string]string, order ...string) string {
+	t.Helper()
+	fakeMachine(t)
+	runtime := filepath.Join(runUserDir, strconv.Itoa(os.Getuid()))
+	t.Setenv("USER", "op")
+	t.Setenv("CM_DIR", "")
+	dir := filepath.Join(runtime, "clipmenu.6.op")
+	if err := os.MkdirAll(dir, 0o700); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(runtime, "bus"), nil, 0o600); err != nil {
+		t.Fatal(err)
+	}
+	var cache strings.Builder
+	for i, line := range order {
+		cache.WriteString(strconv.FormatInt(1_700_000_000_000_000_000+int64(i)*1_000_000_000, 10) + " " + line + "\n")
+		if err := os.WriteFile(filepath.Join(dir, entryID(line)), []byte(clips[line]), 0o600); err != nil {
+			t.Fatal(err)
+		}
+	}
+	if err := os.WriteFile(filepath.Join(dir, "line_cache"), []byte(cache.String()), 0o600); err != nil {
+		t.Fatal(err)
+	}
+	return dir
+}
+
+func TestTheHistoryIsNewestFirstOnceEachWithItsText(t *testing.T) {
+	store(t, map[string]string{"first": "first", "second (2 lines)": "second\nline two"}, "first", "second (2 lines)", "first")
+	fakeProcess(t, nobody, "clipmenud")
+	h, err := History(10, 4096)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !h.Collecting || h.Total != 2 || h.Entries[0].Line != "first" || h.Entries[1].Text != "second\nline two" || h.Entries[1].Bytes != 15 {
+		t.Fatalf("%+v", h)
+	}
+	if h, _ := History(1, 3); len(h.Entries) != 1 || h.Entries[0].Text != "fir" || !h.Entries[0].Truncated {
+		t.Fatalf("limited and cut: %+v", h)
+	}
+	if h, _ := History(10, 0); h.Entries[0].Text != "" || h.Entries[0].Bytes != 5 {
+		t.Fatalf("without text: %+v", h)
+	}
+}
+
+func TestAnEntryIsDeletedByIdOrLineWithItsText(t *testing.T) {
+	dir := store(t, map[string]string{"a": "a", "b": "b", "c": "c"}, "a", "b", "c", "a")
+	r, err := Delete(entryID("a"), "")
+	if err != nil || r.Removed != 2 || r.Remaining != 2 {
+		t.Fatalf("by id, both copies: %+v, %v", r, err)
+	}
+	if _, err := os.Stat(filepath.Join(dir, entryID("a"))); !errors.Is(err, os.ErrNotExist) {
+		t.Fatal("the text stayed")
+	}
+	if r, err := Delete("", "b"); err != nil || r.Removed != 1 || r.Remaining != 1 {
+		t.Fatalf("by line: %+v, %v", r, err)
+	}
+	if _, err := Delete("", "zzz"); err == nil {
+		t.Fatal("a missing entry was reported deleted")
+	}
+	if _, err := Delete("x", "y"); err == nil {
+		t.Fatal("both an id and a line were accepted")
+	}
+	cache, _ := os.ReadFile(filepath.Join(dir, "line_cache"))
+	if !strings.HasSuffix(string(cache), " c\n") || strings.Count(string(cache), "\n") != 1 {
+		t.Fatalf("line cache: %q", cache)
+	}
+}
+
+func TestClearForgetsEverythingButKeepsTheDaemonsLocks(t *testing.T) {
+	dir := store(t, map[string]string{"a": "a", "b": "b"}, "a", "b")
+	if err := os.WriteFile(filepath.Join(dir, "session_lock"), nil, 0o600); err != nil {
+		t.Fatal(err)
+	}
+	r, err := Clear()
+	if err != nil || r.Removed != 2 {
+		t.Fatalf("%+v, %v", r, err)
+	}
+	left, _ := os.ReadDir(dir)
+	var names []string
+	for _, f := range left {
+		names = append(names, f.Name())
+	}
+	if strings.Join(names, ",") != "line_cache,lock,session_lock" {
+		t.Fatalf("left: %v", names)
+	}
+}
+
+func TestCopyHandsTheTextToAnOwnerUnderTheAccountsServiceManager(t *testing.T) {
+	store(t, nil)
+	fakeProcess(t, nobody, "i3", "DISPLAY=:1")
+	bin := fakeBinaries(t, map[string]string{"systemctl": "true", "systemd-run": `echo "$*" > "$LOG"; for last; do :; done; cat "$last" > "$LOG.text"`})
+	t.Setenv("LOG", filepath.Join(bin, "log"))
+	r, err := Copy("secret-free text")
+	if err != nil || r.Bytes != 16 || !strings.HasPrefix(r.Unit, "clipmenu-copy-") {
+		t.Fatalf("%+v, %v", r, err)
+	}
+	asked, _ := os.ReadFile(filepath.Join(bin, "log"))
+	if !strings.Contains(string(asked), "--setenv=DISPLAY=:1 -- /bin/sh -c xsel --nodetach --input --clipboard") {
+		t.Fatalf("asked: %s", asked)
+	}
+	handed, _ := os.ReadFile(filepath.Join(bin, "log.text"))
+	if string(handed) != "secret-free text" {
+		t.Fatalf("handed over: %q", handed)
+	}
+	if _, err := Copy(""); err == nil {
+		t.Fatal("empty text was accepted")
+	}
+}
+
+func TestPasteReadsTheClipboardOrSaysThereIsNoSession(t *testing.T) {
+	fakeMachine(t)
+	if _, err := Paste(); !errors.Is(err, ErrNoSession) {
+		t.Fatal(err)
+	}
+	fakeProcess(t, nobody, "i3", "DISPLAY=:1")
+	fakeBinaries(t, map[string]string{"xsel": `[ "$*" = "--output --clipboard" ] && printf 'on the clipboard'`})
+	p, err := Paste()
+	if err != nil || p.Text != "on the clipboard" || p.Bytes != 16 {
+		t.Fatalf("%+v, %v", p, err)
+	}
+}
+
+func TestWithoutAStoreTheChangesSayWhy(t *testing.T) {
+	fakeMachine(t)
+	runtime := filepath.Join(runUserDir, strconv.Itoa(os.Getuid()))
+	if err := os.MkdirAll(runtime, 0o700); err != nil {
+		t.Fatal(err)
+	}
+	t.Setenv("USER", "op")
+	if _, err := Clear(); err == nil || !strings.Contains(err.Error(), "clipmenud has not run") {
+		t.Fatal(err)
+	}
+	if h, err := History(5, 0); err != nil || h.Total != 0 || h.Collecting {
+		t.Fatalf("an empty history: %+v, %v", h, err)
+	}
+}

modules/clipmenu/cmd/clipmenu-tools/main.go

@@ -0,0 +1,90 @@
+// clipmenu's Go tools bundle (novox/hq ADR 0188, ADR 0193, ADR 0208): its implementation of
+// node-clipboard's verbs `history` and `copy`, and its own tools, served by the node's runtime as the
+// operator account. The history is read from clipmenu's own store in the account's runtime directory;
+// the clipboard itself is the X session's.
+package main
+
+import (
+	"fmt"
+	"os"
+
+	stdio "git.novox.be/novox/mesh-sdk/go"
+)
+
+func main() {
+	if err := stdio.Serve("", tools()); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
+
+func tools() []stdio.Tool {
+	return []stdio.Tool{
+		{
+			Name: "node-clipboard.history",
+			Description: "What the operator copied, newest first: each entry's id, its first line, when, its size " +
+				"and its text (each cut at max_bytes). Whether the clipboard daemon is collecting.",
+			Input: map[string]any{
+				"limit":     map[string]any{"type": "integer", "description": "at most this many entries (default 20, at most 500)"},
+				"max_bytes": map[string]any{"type": "integer", "description": "cut each entry's text at this many bytes; 0 leaves the text out (default 4096, at most 65536)"},
+			},
+			Run: func(args map[string]any) (any, error) {
+				limit, err := whole(args, "limit", 20, 1, 500)
+				if err != nil {
+					return nil, err
+				}
+				most, err := whole(args, "max_bytes", 4096, 0, 65536)
+				if err != nil {
+					return nil, err
+				}
+				return History(limit, most)
+			},
+		},
+		{
+			Name: "node-clipboard.copy",
+			Description: "Put text on the operator's clipboard, as if they had copied it; it enters the history " +
+				"like any copy. Answers how many bytes.",
+			Input: map[string]any{
+				"type": "object",
+				"properties": map[string]any{
+					"text": map[string]any{"type": "string", "description": fmt.Sprintf("the text (at most %d bytes)", mostCopy)},
+				},
+				"required": []string{"text"},
+			},
+			Run: func(args map[string]any) (any, error) {
+				t, ok := args["text"].(string)
+				if !ok {
+					return nil, fmt.Errorf("text is required, as a string")
+				}
+				return Copy(t)
+			},
+		},
+		{
+			Name:        "clipmenu_paste",
+			Description: "What the operator's clipboard holds right now, as text (cut at 64 KiB, said in truncated).",
+			Run:         func(map[string]any) (any, error) { return Paste() },
+		},
+		{
+			Name:        "clipmenu_clear",
+			Description: "Forget the whole clipboard history. What is on the clipboard now stays there.",
+			Run:         func(map[string]any) (any, error) { return Clear() },
+		},
+		{
+			Name: "clipmenu_delete",
+			Description: "Forget one entry of the clipboard history, by its id as the history answers it, or by " +
+				"its first line exactly.",
+			Input: map[string]any{
+				"id":   map[string]any{"type": "string", "description": "the entry's id"},
+				"line": map[string]any{"type": "string", "description": "the entry's first line, exactly"},
+			},
+			Run: func(args map[string]any) (any, error) {
+				id, err := text(args, "id", false)
+				if err != nil {
+					return nil, err
+				}
+				line, _ := args["line"].(string)
+				return Delete(id, line)
+			},
+		},
+	}
+}

modules/clipmenu/cmd/clipmenu-tools/manifest_helpers_test.go

@@ -0,0 +1,175 @@
+package main
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+// The module's manifest, read the way the catalogue reads it, for the manifest tests. The same in
+// every desktop module that carries it.
+
+type manifest struct {
+	Module       string           `json:"module"`
+	Version      string           `json:"version"`
+	Capabilities []string         `json:"capabilities"`
+	Requires     []string         `json:"requires"`
+	Claims       []claim          `json:"claims"`
+	Seats        []any            `json:"seats"`
+	Tools        []string         `json:"tools"`
+	Environment  *environment     `json:"environment"`
+	Shell        []shellCode      `json:"shell"`
+	Resources    []map[string]any `json:"resources"`
+	Build        struct {
+		Artifacts []map[string]any `json:"artifacts"`
+	} `json:"build"`
+}
+
+type claim struct {
+	Name   string   `json:"name"`
+	Scope  string   `json:"scope"`
+	Serves []string `json:"serves"`
+}
+
+type environment struct {
+	Variables map[string]string `json:"variables"`
+	Path      []map[string]any  `json:"path"`
+}
+
+type shellCode struct {
+	For  string `json:"for"`
+	Slot string `json:"slot"`
+	Code string `json:"code"`
+}
+
+func readManifest(t *testing.T) manifest {
+	t.Helper()
+	raw, err := os.ReadFile(filepath.Join("..", "..", "module.json"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	dec := json.NewDecoder(strings.NewReader(string(raw)))
+	dec.DisallowUnknownFields()
+	var m manifest
+	if err := dec.Decode(&m); err != nil {
+		t.Fatalf("module.json: %v", err)
+	}
+	return m
+}
+
+func (m manifest) resource(t *testing.T, id string) map[string]any {
+	t.Helper()
+	for _, r := range m.Resources {
+		if r["id"] == id {
+			return r
+		}
+	}
+	t.Fatalf("no resource %q", id)
+	return nil
+}
+
+func (m manifest) packages() (present, absent []string) {
+	for _, r := range m.Resources {
+		if r["type"] == "package" {
+			if r["absent"] == true {
+				absent = append(absent, r["package"].(string))
+			} else {
+				present = append(present, r["package"].(string))
+			}
+		}
+	}
+	return present, absent
+}
+
+// sameAsSource checks that a file resource's content is byte for byte the module's source file, so
+// the readable file in the repository is what the machine gets.
+func (m manifest) sameAsSource(t *testing.T, id, source string) {
+	t.Helper()
+	want, err := os.ReadFile(filepath.Join("..", "..", source))
+	if err != nil {
+		t.Fatal(err)
+	}
+	r := m.resource(t, id)
+	if r["type"] != "file" {
+		t.Fatalf("%s is a %v, not a file", id, r["type"])
+	}
+	if got, _ := r["content"].(string); got != string(want) {
+		t.Fatalf("resource %s's content is not %s: edit the source and copy it into module.json", id, source)
+	}
+	if r["owner"] != "${machine:account}" && !strings.HasPrefix(r["path"].(string), "/etc/") {
+		t.Fatalf("%s under the home is the account's", id)
+	}
+}
+
+// checkTheToolsAgree checks that the manifest lists the module's own tools exactly, that the bundle
+// serves each seat verb the claims promise as <seat>.<verb>, and that the Go bundle is declared.
+func checkTheToolsAgree(t *testing.T, m manifest) {
+	t.Helper()
+	own, seat := map[string]bool{}, map[string]bool{}
+	for _, tool := range tools() {
+		if strings.Contains(tool.Name, ".") {
+			seat[tool.Name] = true
+		} else {
+			own[tool.Name] = true
+		}
+		if strings.TrimSpace(tool.Description) == "" {
+			t.Errorf("%s has no description", tool.Name)
+		}
+	}
+	listed := map[string]bool{}
+	for _, name := range m.Tools {
+		listed[name] = true
+		if !own[name] {
+			t.Errorf("module.json lists %s, which the bundle does not serve", name)
+		}
+	}
+	for name := range own {
+		if !listed[name] {
+			t.Errorf("the bundle serves %s, which module.json does not list", name)
+		}
+		if !strings.HasPrefix(name, strings.ReplaceAll(m.Module, "-", "_")+"_") {
+			t.Errorf("%s is not prefixed with the module's name", name)
+		}
+	}
+	promised := map[string]bool{}
+	for _, c := range m.Claims {
+		for _, verb := range c.Serves {
+			promised[c.Name+"."+verb] = true
+			if !seat[c.Name+"."+verb] {
+				t.Errorf("the claim on %s promises %s, which the bundle does not serve", c.Name, verb)
+			}
+		}
+	}
+	for name := range seat {
+		if !promised[name] {
+			t.Errorf("the bundle serves %s, which no claim promises", name)
+		}
+	}
+	var bundle map[string]any
+	for _, a := range m.Build.Artifacts {
+		if a["kind"] == "bundle" {
+			bundle = a
+		}
+	}
+	if bundle == nil || bundle["language"] != "go" || bundle["system"] != "arch" ||
+		bundle["from"] != "cmd/"+m.Module+"-tools" || bundle["binary"] != m.Module+"-tools" {
+		t.Errorf("the Go tools bundle: %v", bundle)
+	}
+}
+
+// checkNoSecretsOrInstallationNames refuses what a catalogue manifest must never carry.
+func checkNoSecretsOrInstallationNames(t *testing.T) {
+	t.Helper()
+	raw, err := os.ReadFile(filepath.Join("..", "..", "module.json"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	s := strings.ToLower(string(raw))
+	for _, never := range []string{"/home/", "jochen", "g14", "shanks", "novox.be", "api_key", ".hal/", "greenclip daemon"} {
+		if strings.Contains(s, never) {
+			t.Errorf("module.json names %q", never)
+		}
+	}
+}

modules/clipmenu/cmd/clipmenu-tools/manifest_test.go

@@ -0,0 +1,64 @@
+package main
+
+import (
+	"reflect"
+	"strings"
+	"testing"
+)
+
+// clipmenu's shape (novox/hq ADR 0208, research 026/04): it claims node-clipboard serving history
+// and copy, requires the X display on its own machine, replaces greenclip, starts its daemon once
+// from the session's start, and binds its menu as an i3 drop-in through the launcher's dmenu command.
+
+func TestItClaimsTheClipboardSeatServingHistoryAndCopy(t *testing.T) {
+	m := readManifest(t)
+	if m.Module != "clipmenu" || m.Seats != nil {
+		t.Fatalf("module %q declares seats %v", m.Module, m.Seats)
+	}
+	if !reflect.DeepEqual(m.Claims, []claim{{Name: "node-clipboard", Scope: "node", Serves: []string{"history", "copy"}}}) {
+		t.Fatalf("claims: %+v", m.Claims)
+	}
+	if !reflect.DeepEqual(m.Requires, []string{"x11-display"}) {
+		t.Fatalf("requires: %v", m.Requires)
+	}
+	present, absent := m.packages()
+	if !reflect.DeepEqual(present, []string{"clipmenu"}) || !reflect.DeepEqual(absent, []string{"rofi-greenclip"}) {
+		t.Fatalf("packages: %v, absent %v", present, absent)
+	}
+}
+
+func TestTheDaemonStartsOnceFromTheSessionsStart(t *testing.T) {
+	m := readManifest(t)
+	if len(m.Shell) != 1 || m.Shell[0].For != "xinitrc" || m.Shell[0].Slot != "normal" {
+		t.Fatalf("%+v", m.Shell)
+	}
+	code := m.Shell[0].Code
+	if strings.Count(code, "\nclipmenud &\n") != 1 || strings.Contains(code, "greenclip") {
+		t.Fatalf("%q", code)
+	}
+	for _, r := range m.Resources {
+		if r["type"] == "service" || r["type"] == "process" {
+			t.Fatalf("a second start: %v", r)
+		}
+	}
+}
+
+func TestItsSettingsAreEnvironmentAndItsMenuIsTheLaunchersDmenu(t *testing.T) {
+	m := readManifest(t)
+	if !reflect.DeepEqual(m.Environment.Variables, map[string]string{"CM_SELECTIONS": "clipboard", "CM_MAX_CLIPS": "500", "CM_HISTLENGTH": "15"}) {
+		t.Fatalf("%v", m.Environment.Variables)
+	}
+	if _, set := m.Environment.Variables["CM_LAUNCHER"]; set {
+		t.Fatal("the launcher is clipmenu's default, dmenu: the seat's command")
+	}
+	m.sameAsSource(t, "i3-bindings", "files/i3/50-clipmenu.conf")
+	if c := m.resource(t, "i3-bindings")["content"].(string); !strings.Contains(c, "bindsym $mod+period exec --no-startup-id clipmenu") {
+		t.Fatalf("%s", c)
+	}
+}
+
+func TestTheToolsAgreeWithTheManifest(t *testing.T) {
+	m := readManifest(t)
+	checkTheToolsAgree(t, m)
+	checkNoSecretsOrInstallationNames(t)
+}

modules/clipmenu/cmd/clipmenu-tools/session.go

@@ -0,0 +1,423 @@
+// The operator's graphical session, as a tool the node's runtime runs finds it (novox/hq ADR 0208).
+//
+// The runtime is a system service running as the operator account (ADR 0175): it has the account's
+// uid and none of the session's environment — no DISPLAY, no XAUTHORITY, no session bus. A tool that
+// draws on the screen or talks to the desktop's D-Bus must find them. It reads them from a process of
+// the account that is part of the session (the window manager first), the same thing `loginctl` and
+// a person's own shell would point at, and says where it found them.
+//
+// Long-lived programs a tool starts go to the account's own service manager through `systemd-run
+// --user`, never as children of the tool: the runtime's unit is a cgroup the service manager empties
+// whenever the runtime restarts, and a compositor or a clipboard owner started from inside it would
+// die with it.
+//
+// This file is the same in every desktop module that carries it; it moves into the Go SDK once a
+// second consumer outside the desktop wants it.
+package main
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"sort"
+	"strconv"
+	"strings"
+	"syscall"
+	"time"
+)
+
+// Where the session is looked for. Variables so a test can point them at a fake tree.
+var (
+	procRoot   = "/proc"
+	runUserDir = "/run/user"
+	x11Sockets = "/tmp/.X11-unix"
+)
+
+// sessionHolders are the processes whose environment is the session's, best first: the window
+// manager is the session, the rest are its children. Anything else carrying DISPLAY ranks after them.
+var sessionHolders = []string{"i3", "sway", "i3bar", "picom", "xss-lock", "dunst", "clipmenud", "xterm"}
+
+// sessionKeys are the variables a session carries that a tool hands on to what it runs.
+var sessionKeys = []string{"DISPLAY", "XAUTHORITY", "WAYLAND_DISPLAY", "DBUS_SESSION_BUS_ADDRESS",
+	"XDG_RUNTIME_DIR", "XDG_SESSION_ID", "I3SOCK"}
+
+// Session is what a tool needs to reach the operator's desktop.
+type Session struct {
+	UID        int    `json:"uid"`
+	Display    string `json:"display,omitempty"`
+	XAuthority string `json:"xauthority,omitempty"`
+	Wayland    string `json:"wayland_display,omitempty"`
+	Bus        string `json:"bus,omitempty"`
+	RuntimeDir string `json:"runtime_dir,omitempty"`
+	SessionID  string `json:"session_id,omitempty"`
+	I3Sock     string `json:"i3sock,omitempty"`
+	// From says where the values were found: the tool's own environment, a process, or the socket.
+	From string `json:"from"`
+}
+
+// ErrNoSession is answered by a tool that needs the desktop when nobody is logged in to it.
+var ErrNoSession = errors.New("no graphical session")
+
+// ErrTimedOut is what run answers for a command ended because it ran past its time.
+var ErrTimedOut = errors.New("timed out")
+
+// ErrNoBus is answered by a tool that needs the session bus when the account has none.
+var ErrNoBus = errors.New("no session bus")
+
+// operatorHome is the account's home: what the runtime was told, else the process's own.
+func operatorHome() string {
+	if h := strings.TrimSpace(os.Getenv("MESH_OPERATOR_HOME")); h != "" {
+		return h
+	}
+	h, _ := os.UserHomeDir()
+	return h
+}
+
+// findSession finds the graphical session of the account this tool runs as, or answers
+// ErrNoSession with what it looked at.
+func findSession() (Session, error) {
+	s := findEnvironment()
+	if s.Display == "" && s.Wayland == "" {
+		return s, fmt.Errorf("%w for uid %d on this machine: no process of the account carries DISPLAY "+
+			"or WAYLAND_DISPLAY, and no X server socket in %s has an authority file to go with it. "+
+			"Is anyone logged in to the desktop?", ErrNoSession, s.UID, x11Sockets)
+	}
+	return s, nil
+}
+
+// findBus finds the account's session bus, which a logged-in account has whether or not a desktop
+// is running.
+func findBus() (Session, error) {
+	s := findEnvironment()
+	if s.Bus == "" {
+		return s, fmt.Errorf("%w for uid %d: DBUS_SESSION_BUS_ADDRESS is not set and %s does not exist "+
+			"(the account is not logged in)", ErrNoBus, s.UID, filepath.Join(runUserDir, strconv.Itoa(s.UID), "bus"))
+	}
+	return s, nil
+}
+
+func findEnvironment() Session {
+	uid := os.Getuid()
+	s := Session{UID: uid}
+	own := map[string]string{}
+	for _, k := range sessionKeys {
+		own[k] = os.Getenv(k)
+	}
+	if own["DISPLAY"] != "" || own["WAYLAND_DISPLAY"] != "" {
+		s.fill(own)
+		s.From = "the tool's own environment"
+	} else if pid, comm, env, ok := sessionProcess(uid); ok {
+		s.fill(env)
+		s.From = fmt.Sprintf("process %s (pid %d)", comm, pid)
+	} else if display, ok := lonelyX11Socket(); ok {
+		if a := filepath.Join(operatorHome(), ".Xauthority"); exists(a) {
+			s.Display, s.XAuthority = display, a
+			s.From = "the X server socket and the account's ~/.Xauthority"
+		}
+		s.fill(own)
+	} else {
+		s.fill(own)
+		s.From = "nothing: no session found"
+	}
+	// The bus and the runtime directory are the account's, whether or not the process named them.
+	runtime := filepath.Join(runUserDir, strconv.Itoa(uid))
+	if s.RuntimeDir == "" && exists(runtime) {
+		s.RuntimeDir = runtime
+	}
+	if s.Bus == "" && s.RuntimeDir != "" && exists(filepath.Join(s.RuntimeDir, "bus")) {
+		s.Bus = "unix:path=" + filepath.Join(s.RuntimeDir, "bus")
+	}
+	return s
+}
+
+func (s *Session) fill(env map[string]string) {
+	set := func(dst *string, key string) {
+		if *dst == "" {
+			*dst = env[key]
+		}
+	}
+	set(&s.Display, "DISPLAY")
+	set(&s.XAuthority, "XAUTHORITY")
+	set(&s.Wayland, "WAYLAND_DISPLAY")
+	set(&s.Bus, "DBUS_SESSION_BUS_ADDRESS")
+	set(&s.RuntimeDir, "XDG_RUNTIME_DIR")
+	set(&s.SessionID, "XDG_SESSION_ID")
+	set(&s.I3Sock, "I3SOCK")
+}
+
+// sessionProcess is the best process of this uid whose environment names a display.
+func sessionProcess(uid int) (int, string, map[string]string, bool) {
+	entries, err := os.ReadDir(procRoot)
+	if err != nil {
+		return 0, "", nil, false
+	}
+	type candidate struct {
+		pid  int
+		comm string
+		env  map[string]string
+		rank int
+	}
+	var found []candidate
+	for _, e := range entries {
+		pid, err := strconv.Atoi(e.Name())
+		if err != nil {
+			continue
+		}
+		dir := filepath.Join(procRoot, e.Name())
+		if owner, ok := ownerOf(dir); !ok || owner != uid {
+			continue
+		}
+		raw, err := os.ReadFile(filepath.Join(dir, "environ"))
+		if err != nil {
+			continue
+		}
+		env := parseEnviron(raw)
+		if env["DISPLAY"] == "" && env["WAYLAND_DISPLAY"] == "" {
+			continue
+		}
+		comm := readTrimmed(filepath.Join(dir, "comm"))
+		rank := len(sessionHolders)
+		for i, h := range sessionHolders {
+			if h == comm {
+				rank = i
+				break
+			}
+		}
+		found = append(found, candidate{pid, comm, env, rank})
+	}
+	if len(found) == 0 {
+		return 0, "", nil, false
+	}
+	sort.Slice(found, func(i, j int) bool {
+		if found[i].rank != found[j].rank {
+			return found[i].rank < found[j].rank
+		}
+		return found[i].pid > found[j].pid // the newer of two equals
+	})
+	best := found[0]
+	return best.pid, best.comm, best.env, true
+}
+
+func parseEnviron(raw []byte) map[string]string {
+	env := map[string]string{}
+	for _, kv := range bytes.Split(raw, []byte{0}) {
+		if i := bytes.IndexByte(kv, '='); i > 0 {
+			env[string(kv[:i])] = string(kv[i+1:])
+		}
+	}
+	return env
+}
+
+func ownerOf(path string) (int, bool) {
+	info, err := os.Stat(path)
+	if err != nil {
+		return 0, false
+	}
+	st, ok := info.Sys().(*syscall.Stat_t)
+	if !ok {
+		return 0, false
+	}
+	return int(st.Uid), true
+}
+
+// lonelyX11Socket is the display of the one X server socket there is, when there is exactly one.
+func lonelyX11Socket() (string, bool) {
+	entries, err := os.ReadDir(x11Sockets)
+	if err != nil {
+		return "", false
+	}
+	var displays []string
+	for _, e := range entries {
+		if n := strings.TrimPrefix(e.Name(), "X"); n != e.Name() {
+			if _, err := strconv.Atoi(n); err == nil {
+				displays = append(displays, ":"+n)
+			}
+		}
+	}
+	if len(displays) != 1 {
+		return "", false
+	}
+	return displays[0], true
+}
+
+func readTrimmed(path string) string {
+	b, err := os.ReadFile(path)
+	if err != nil {
+		return ""
+	}
+	return strings.TrimSpace(string(b))
+}
+
+func exists(path string) bool {
+	_, err := os.Stat(path)
+	return err == nil
+}
+
+// Env is this process's environment with the session's variables in place of its own.
+func (s Session) Env() []string {
+	drop := map[string]bool{}
+	for _, k := range sessionKeys {
+		drop[k] = true
+	}
+	var env []string
+	for _, kv := range os.Environ() {
+		if i := strings.IndexByte(kv, '='); i > 0 && drop[kv[:i]] {
+			continue
+		}
+		env = append(env, kv)
+	}
+	add := func(k, v string) {
+		if v != "" {
+			env = append(env, k+"="+v)
+		}
+	}
+	add("DISPLAY", s.Display)
+	add("XAUTHORITY", s.XAuthority)
+	add("WAYLAND_DISPLAY", s.Wayland)
+	add("DBUS_SESSION_BUS_ADDRESS", s.Bus)
+	add("XDG_RUNTIME_DIR", s.RuntimeDir)
+	add("XDG_SESSION_ID", s.SessionID)
+	add("I3SOCK", s.I3Sock)
+	return env
+}
+
+// mostOutput bounds what a command may answer with, per stream.
+const mostOutput = 256 << 10
+
+// Result is what a command did.
+type Result struct {
+	Stdout    string `json:"stdout"`
+	Stderr    string `json:"stderr,omitempty"`
+	Code      int    `json:"code"`
+	Truncated bool   `json:"truncated,omitempty"`
+}
+
+// run runs a command in the session's environment, its input given, ended with everything it
+// started after timeout. A command that is not installed is an error naming it; one that exits
+// non-zero is a Result with its code, for the caller to judge.
+func (s Session) run(timeout time.Duration, stdin string, name string, args ...string) (Result, error) {
+	path, err := exec.LookPath(name)
+	if err != nil {
+		return Result{}, fmt.Errorf("%s is not installed on this machine", name)
+	}
+	cmd := exec.Command(path, args...)
+	cmd.Env = s.Env()
+	if home := operatorHome(); exists(home) {
+		cmd.Dir = home
+	}
+	if stdin != "" {
+		cmd.Stdin = strings.NewReader(stdin)
+	}
+	var out, errOut capped
+	cmd.Stdout, cmd.Stderr = &out, &errOut
+	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+	if err := cmd.Start(); err != nil {
+		return Result{}, fmt.Errorf("%s: %w", name, err)
+	}
+	done := make(chan error, 1)
+	go func() { done <- cmd.Wait() }()
+	select {
+	case err = <-done:
+	case <-time.After(timeout):
+		_ = syscall.Kill(-cmd.Process.Pid, syscall.SIGKILL)
+		<-done
+		return Result{Stdout: out.String(), Stderr: errOut.String()},
+			fmt.Errorf("%s did not finish within %s and was ended: %w", name, timeout, ErrTimedOut)
+	}
+	r := Result{Stdout: out.String(), Stderr: errOut.String(), Truncated: out.cut || errOut.cut}
+	var exit *exec.ExitError
+	if errors.As(err, &exit) {
+		r.Code = exit.ExitCode()
+	} else if err != nil {
+		return r, fmt.Errorf("%s: %w", name, err)
+	}
+	return r, nil
+}
+
+// detach starts a long-lived program under the account's own service manager, as a transient unit
+// that carries the session's display, so it outlives the runtime that asked for it. A unit already
+// running under the same name is stopped first, so a fixed name means "at most one".
+func (s Session) detach(unit string, args ...string) error {
+	if s.RuntimeDir == "" {
+		return fmt.Errorf("%w: the account's runtime directory is missing, so its service manager "+
+			"cannot be reached", ErrNoBus)
+	}
+	_, _ = s.run(5*time.Second, "", "systemctl", "--user", "stop", unit+".service")
+	call := []string{"--user", "--collect", "--quiet", "--unit=" + unit}
+	for _, kv := range [][2]string{{"DISPLAY", s.Display}, {"XAUTHORITY", s.XAuthority},
+		{"WAYLAND_DISPLAY", s.Wayland}, {"XDG_SESSION_ID", s.SessionID}, {"I3SOCK", s.I3Sock}} {
+		if kv[1] != "" {
+			call = append(call, "--setenv="+kv[0]+"="+kv[1])
+		}
+	}
+	call = append(call, "--")
+	call = append(call, args...)
+	r, err := s.run(10*time.Second, "", "systemd-run", call...)
+	if err != nil {
+		return err
+	}
+	if r.Code != 0 {
+		return fmt.Errorf("systemd-run %s: %s", unit, strings.TrimSpace(r.Stderr))
+	}
+	return nil
+}
+
+// uniqueUnit is a transient unit name that will not collide with an earlier one.
+func uniqueUnit(prefix string) string {
+	return fmt.Sprintf("%s-%d", prefix, time.Now().UnixNano())
+}
+
+type capped struct {
+	bytes.Buffer
+	cut bool
+}
+
+func (c *capped) Write(p []byte) (int, error) {
+	if room := mostOutput - c.Len(); room < len(p) {
+		if room > 0 {
+			c.Buffer.Write(p[:room])
+		}
+		c.cut = true
+		return len(p), nil
+	}
+	return c.Buffer.Write(p)
+}
+
+// processesOf are the pids of this uid's processes whose command name is comm, oldest first.
+func processesOf(comm string) []int {
+	entries, err := os.ReadDir(procRoot)
+	if err != nil {
+		return nil
+	}
+	uid := os.Getuid()
+	var pids []int
+	for _, e := range entries {
+		pid, err := strconv.Atoi(e.Name())
+		if err != nil {
+			continue
+		}
+		dir := filepath.Join(procRoot, e.Name())
+		if owner, ok := ownerOf(dir); !ok || owner != uid {
+			continue
+		}
+		if readTrimmed(filepath.Join(dir, "comm")) == comm {
+			pids = append(pids, pid)
+		}
+	}
+	sort.Ints(pids)
+	return pids
+}
+
+// signalAll sends sig to every process of this uid named comm, and answers the pids it reached.
+func signalAll(comm string, sig syscall.Signal) []int {
+	var reached []int
+	for _, pid := range processesOf(comm) {
+		if syscall.Kill(pid, sig) == nil {
+			reached = append(reached, pid)
+		}
+	}
+	return reached
+}

modules/clipmenu/cmd/clipmenu-tools/session_test.go

@@ -0,0 +1,174 @@
+package main
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"testing"
+	"time"
+)
+
+// fakeMachine points the session finder at a temporary /proc, /run/user and X socket directory, with
+// none of the test process's own session variables, and gives back the root.
+func fakeMachine(t *testing.T) string {
+	t.Helper()
+	root := t.TempDir()
+	procRoot, runUserDir, x11Sockets = filepath.Join(root, "proc"), filepath.Join(root, "run-user"), filepath.Join(root, "x11")
+	for _, d := range []string{procRoot, runUserDir, x11Sockets} {
+		if err := os.MkdirAll(d, 0o755); err != nil {
+			t.Fatal(err)
+		}
+	}
+	for _, k := range sessionKeys {
+		t.Setenv(k, "")
+	}
+	t.Setenv("MESH_OPERATOR_HOME", filepath.Join(root, "home"))
+	t.Cleanup(func() { procRoot, runUserDir, x11Sockets = "/proc", "/run/user", "/tmp/.X11-unix" })
+	return root
+}
+
+func fakeProcess(t *testing.T, pid int, comm string, env ...string) {
+	t.Helper()
+	dir := filepath.Join(procRoot, strconv.Itoa(pid))
+	if err := os.MkdirAll(dir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(dir, "comm"), []byte(comm+"\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(dir, "environ"), []byte(strings.Join(env, "\x00")+"\x00"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestTheSessionIsReadFromTheWindowManagerBeforeAnyOtherProcess(t *testing.T) {
+	fakeMachine(t)
+	fakeProcess(t, 900, "xterm", "DISPLAY=:9", "XAUTHORITY=/elsewhere")
+	fakeProcess(t, 100, "i3", "DISPLAY=:1", "XAUTHORITY=/home/op/.Xauthority",
+		"DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus", "XDG_SESSION_ID=3", "SECRET_TOKEN=never-copied")
+	fakeProcess(t, 50, "bash", "PATH=/usr/bin")
+	s, err := findSession()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if s.Display != ":1" || s.XAuthority != "/home/op/.Xauthority" || s.SessionID != "3" || !strings.Contains(s.From, "i3 (pid 100)") {
+		t.Fatalf("the window manager's environment: %+v", s)
+	}
+	for _, kv := range s.Env() {
+		if strings.HasPrefix(kv, "SECRET_TOKEN=") {
+			t.Fatal("a variable of the session process that is not a session variable was handed on")
+		}
+	}
+}
+
+func TestAnyProcessCarryingADisplayServesWhenTheWindowManagerIsNotFound(t *testing.T) {
+	fakeMachine(t)
+	fakeProcess(t, 10, "firefox", "DISPLAY=:0")
+	fakeProcess(t, 20, "firefox", "DISPLAY=:2")
+	s, err := findSession()
+	if err != nil || s.Display != ":2" {
+		t.Fatalf("the newest of two equals: %+v, %v", s, err)
+	}
+}
+
+func TestNoSessionIsAClearAnswerNotAGuess(t *testing.T) {
+	fakeMachine(t)
+	fakeProcess(t, 10, "sshd", "PATH=/usr/bin")
+	_, err := findSession()
+	if !errors.Is(err, ErrNoSession) || !strings.Contains(err.Error(), "logged in to the desktop") {
+		t.Fatalf("no session: %v", err)
+	}
+}
+
+func TestOneXSocketAndTheAccountsAuthorityFileAreASession(t *testing.T) {
+	root := fakeMachine(t)
+	if err := os.WriteFile(filepath.Join(x11Sockets, "X0"), nil, 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.MkdirAll(filepath.Join(root, "home"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(root, "home", ".Xauthority"), nil, 0o600); err != nil {
+		t.Fatal(err)
+	}
+	s, err := findSession()
+	if err != nil || s.Display != ":0" || !strings.HasSuffix(s.XAuthority, "/home/.Xauthority") {
+		t.Fatalf("socket and authority: %+v, %v", s, err)
+	}
+}
+
+func TestTheBusIsTheAccountsRuntimeDirectoryWhenNoProcessNamesIt(t *testing.T) {
+	fakeMachine(t)
+	runtime := filepath.Join(runUserDir, strconv.Itoa(os.Getuid()))
+	if _, err := findBus(); !errors.Is(err, ErrNoBus) {
+		t.Fatalf("no runtime directory is no bus: %v", err)
+	}
+	if err := os.MkdirAll(runtime, 0o700); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(runtime, "bus"), nil, 0o600); err != nil {
+		t.Fatal(err)
+	}
+	s, err := findBus()
+	if err != nil || s.Bus != "unix:path="+filepath.Join(runtime, "bus") || s.RuntimeDir != runtime {
+		t.Fatalf("bus: %+v, %v", s, err)
+	}
+	env := strings.Join(s.Env(), "\n")
+	if !strings.Contains(env, "XDG_RUNTIME_DIR="+runtime) || !strings.Contains(env, "DBUS_SESSION_BUS_ADDRESS=unix:path=") {
+		t.Fatalf("the bus is handed on: %s", env)
+	}
+}
+
+func TestACommandIsBoundedAndANonZeroExitIsAResult(t *testing.T) {
+	fakeMachine(t)
+	s := Session{}
+	r, err := s.run(5*time.Second, "in", "sh", "-c", "cat; echo err >&2; exit 3")
+	if err != nil || r.Stdout != "in" || r.Code != 3 || strings.TrimSpace(r.Stderr) != "err" {
+		t.Fatalf("result: %+v, %v", r, err)
+	}
+	start := time.Now()
+	if _, err := s.run(200*time.Millisecond, "", "sh", "-c", "sleep 30 & sleep 30"); err == nil || time.Since(start) > 5*time.Second {
+		t.Fatalf("a command past its time is ended with what it started: %v after %s", err, time.Since(start))
+	}
+	if _, err := s.run(time.Second, "", "no-such-program-here"); err == nil || !strings.Contains(err.Error(), "not installed") {
+		t.Fatalf("a missing program: %v", err)
+	}
+}
+
+func TestDetachAsksTheAccountsServiceManagerWithTheSessionsDisplay(t *testing.T) {
+	fakeMachine(t)
+	bin := fakeBinaries(t, map[string]string{
+		"systemctl":   `echo "systemctl $*" >> "$LOG"`,
+		"systemd-run": `echo "systemd-run $*" >> "$LOG"`,
+	})
+	log := filepath.Join(bin, "log")
+	t.Setenv("LOG", log)
+	s := Session{Display: ":1", XAuthority: "/x", RuntimeDir: "/run/user/1"}
+	if err := s.detach("picom-session", "picom", "--config", "/c"); err != nil {
+		t.Fatal(err)
+	}
+	got, _ := os.ReadFile(log)
+	want := "systemctl --user stop picom-session.service\n" +
+		"systemd-run --user --collect --quiet --unit=picom-session --setenv=DISPLAY=:1 --setenv=XAUTHORITY=/x -- picom --config /c\n"
+	if string(got) != want {
+		t.Fatalf("detach ran:\n%s\nwant:\n%s", got, want)
+	}
+	if err := (Session{}).detach("x", "y"); !errors.Is(err, ErrNoBus) {
+		t.Fatalf("no runtime directory: %v", err)
+	}
+}
+
+// fakeBinaries puts shell scripts named for programs first on PATH, and answers their directory.
+func fakeBinaries(t *testing.T, scripts map[string]string) string {
+	t.Helper()
+	dir := t.TempDir()
+	for name, body := range scripts {
+		if err := os.WriteFile(filepath.Join(dir, name), []byte("#!/bin/sh\n"+body+"\n"), 0o755); err != nil {
+			t.Fatal(err)
+		}
+	}
+	t.Setenv("PATH", dir+string(os.PathListSeparator)+os.Getenv("PATH"))
+	return dir
+}

modules/clipmenu/files/i3/50-clipmenu.conf

@@ -0,0 +1,5 @@
+# The clipboard's history key (module clipmenu, novox/hq ADR 0208). Owned by the mesh: replaced at
+# every push. clipmenu shows the history through `dmenu`, the node's dmenu-compatible command, which
+# the holder of node-launcher answers (rofi on the workstations); the chosen entry is put back on the
+# clipboard.
+bindsym $mod+period exec --no-startup-id clipmenu -p Clipboard

modules/clipmenu/go.mod

@@ -0,0 +1,5 @@
+module clipmenu
+
+go 1.22
+
+require git.novox.be/novox/mesh-sdk/go v0.1.7

modules/clipmenu/go.sum

@@ -0,0 +1,2 @@
+git.novox.be/novox/mesh-sdk/go v0.1.7 h1:C0sTQmtTiyYH7bnqZb7PusXnqA37gKuT7Nqjn9gG47w=
+git.novox.be/novox/mesh-sdk/go v0.1.7/go.mod h1:GFuZUElBZ9A++mxgIKo97aXXo+kV0uJ/UkbhQPPIbrY=

modules/clipmenu/module.json

@@ -0,0 +1,75 @@
+{
+  "module": "clipmenu",
+  "version": "1",
+  "capabilities": [
+    "package-manager"
+  ],
+  "requires": [
+    "x11-display"
+  ],
+  "claims": [
+    {
+      "name": "node-clipboard",
+      "scope": "node",
+      "serves": [
+        "history",
+        "copy"
+      ]
+    }
+  ],
+  "tools": [
+    "clipmenu_paste",
+    "clipmenu_clear",
+    "clipmenu_delete"
+  ],
+  "environment": {
+    "variables": {
+      "CM_SELECTIONS": "clipboard",
+      "CM_MAX_CLIPS": "500",
+      "CM_HISTLENGTH": "15"
+    }
+  },
+  "shell": [
+    {
+      "for": "xinitrc",
+      "slot": "normal",
+      "code": "# The clipboard's history (module clipmenu, novox/hq ADR 0208): clipmenud collects every copy from\n# here on, once per session. It keeps the history in the account's runtime directory, so a reboot\n# forgets it, and with it every password that was ever copied.\nclipmenud &\n"
+    }
+  ],
+  "resources": [
+    {
+      "id": "package",
+      "type": "package",
+      "package": "clipmenu"
+    },
+    {
+      "id": "greenclip",
+      "type": "package",
+      "package": "rofi-greenclip",
+      "absent": true
+    },
+    {
+      "id": "i3-bindings",
+      "type": "file",
+      "path": "${machine:account-home}/.config/i3/config.d/50-clipmenu.conf",
+      "owner": "${machine:account}",
+      "mode": "0644",
+      "content": "# The clipboard's history key (module clipmenu, novox/hq ADR 0208). Owned by the mesh: replaced at\n# every push. clipmenu shows the history through `dmenu`, the node's dmenu-compatible command, which\n# the holder of node-launcher answers (rofi on the workstations); the chosen entry is put back on the\n# clipboard.\nbindsym $mod+period exec --no-startup-id clipmenu -p Clipboard\n"
+    }
+  ],
+  "build": {
+    "artifacts": [
+      {
+        "name": "tools",
+        "kind": "bundle",
+        "language": "go",
+        "system": "arch",
+        "from": "cmd/clipmenu-tools",
+        "binary": "clipmenu-tools",
+        "loads": [
+          "clipmenu-tools"
+        ]
+      }
+    ]
+  }
+}

modules/cups/README.md

@@ -0,0 +1,84 @@
+# cups
+
+Printing on the two workstations (novox/hq research 027/02: "`cups` with the printer's driver"; to-be 42
+phase 2 step 9).
+
+## Owns
+
+| what | where |
+|---|---|
+| the print scheduler | package `cups` |
+| driverless printing: the filters that turn a document into what an IPP Everywhere printer takes | package `cups-filters` |
+| the scheduler, started on demand and at boot | `cups.socket` and `cups.service`, running and enabled |
+
+All from the official repositories. The queues (`/etc/cups/printers.conf`, the PPDs CUPS generates)
+and the default printer are CUPS's own state, set through its tools. They are found (ADR 0182), and
+the module declares none of them.
+
+## The printer's driver: none needed for the Brother
+
+Research 027 asked for "`cups` with the printer's driver". Measured on 2026-10-04:
+
+| workstation | queue | device | prints through | driver package installed |
+|---|---|---|---|---|
+| laptop | `Brother` (MFC-L8690CDW) | `ipp://` on the LAN | **IPP Everywhere, driverless** | `brother-mfc-l8690cdw` (AUR), unused |
+| desktop | `Brother_MFC_Novox` (default) | `ipp://` on the LAN | **IPP Everywhere, driverless** | `brother-mfc-l8390cdw` and its `-debug` (AUR), unused |
+| desktop | `Kanjuro` (Canon PIXMA MG4200) | `cnijnet:` | the vendor's PPD and filter | `cnijfilter-mg4200` 3.80 (AUR) |
+
+**Both Brother queues already print without a vendor driver.** CUPS's own IPP Everywhere support,
+with `cups-filters`, is the whole driver. The vendor packages installed beside them serve no queue,
+and the laptop's pulls in 32-bit glibc from multilib for a filter nothing runs. So the module declares
+no driver, and the Brother needs nothing outside the official repositories.
+
+**The Canon is the exception, and it is blocked.** Its driver is a user-repository package from 2012,
+with its own network backend. Like snapd, it waits for the mesh's package repository (research 027
+question 1, option P2). Until then it stays as found on the desktop. If the printer answers IPP (check
+with `cups_drivers` on a fresh queue, or `driverless` from `cups-filters`), a driverless queue replaces
+it and the question goes away.
+
+## Improves
+
+- **An owner for the scheduler.** It runs on both workstations today, enabled by nothing the mesh records.
+- **No driver package that nothing uses.** The README's one-off step below removes them, once.
+- **Supplies and state from anywhere.** `cups_printers` answers each queue's toner levels and flags a
+  low one. It also answers why a queue stopped, without opening the printer's page.
+- **The laptop has no default printer**, so a print without a named printer fails there.
+  `cups_default` sets one; it is the operator's choice, not declared.
+
+## Tools
+
+All answer JSON; `(r)` reads, `(a)` acts. They run as the operator account. CUPS lets any account
+print and cancel its own jobs. Setting the default, resuming a printer, and cancelling another
+account's job are kept for its administrators, so those go through `sudo -n`; a cancel tries the
+account first.
+
+| tool | what |
+|---|---|
+| `cups_printers` (r) | every queue: state, enabled, accepting, default, device, make and model, driverless or not, state reasons, supply levels (low flagged) |
+| `cups_queue` (r) | jobs waiting or printing, or the completed ones, newest first, bounded |
+| `cups_cancel` (a) | one job, or every job on a printer |
+| `cups_print` (a) | a file on this machine to a printer or the default, with copies and IPP options; answers the job id |
+| `cups_default` (r/a) | read the default, or set it |
+| `cups_resume` (a) | enable a stopped printer and make it accept jobs |
+| `cups_drivers` (r) | how each queue prints, the packages that bring filters and backends (foreign ones flagged), findings, and the driver models CUPS offers, filtered |
+
+## What changes when it is assigned
+
+Nothing on disk on either workstation: both have `cups` (explicit) and `cups-filters` (as its
+dependency), with `cups.socket` and `cups.service` enabled and running. The packages become the
+mesh's; `cups-filters` is now declared explicitly.
+
+## The one-off step for the operator (ADR 0182)
+
+The mesh removes nothing it did not install. Once the Brother queues are confirmed printing (they do
+today), remove the unused vendor drivers, once:
+
+- **laptop:** `brother-mfc-l8690cdw`, then whatever `pacman -Qdtq` shows it alone pulled in
+  (`lib32-glibc`).
+- **desktop:** `brother-mfc-l8390cdw` and `brother-mfc-l8390cdw-debug`. Keep `cnijfilter-mg4200` while
+  the Canon queue is used.
+
+## Leaves as found
+
+The queues and their PPDs, the default printer, `cups.path` (enabled by the package's preset),
+`system-config-printer` on the desktop, and `cnijfilter-mg4200`.

modules/cups/cmd/cups-tools/cups.go

@@ -0,0 +1,560 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"regexp"
+	"sort"
+	"strconv"
+	"strings"
+)
+
+var queueName = regexp.MustCompile(`^[A-Za-z0-9_.@-]{1,127}$`)
+
+func checkPrinter(p string) error {
+	if !queueName.MatchString(p) || strings.HasPrefix(p, "-") {
+		return fmt.Errorf("%q is not a printer queue's name", p)
+	}
+	return nil
+}
+
+var optionName = regexp.MustCompile(`^[a-z][a-z0-9-]{0,63}$`)
+var optionValue = regexp.MustCompile(`^[A-Za-z0-9._:-]{1,128}$`)
+
+// optionsOf reads the print options object.
+func optionsOf(args map[string]any) (map[string]string, error) {
+	v, ok := args["options"]
+	if !ok || v == nil {
+		return nil, nil
+	}
+	m, ok := v.(map[string]any)
+	if !ok {
+		return nil, fmt.Errorf("options must be an object of names to values")
+	}
+	out := map[string]string{}
+	for k, val := range m {
+		s, ok := val.(string)
+		if !ok || !optionName.MatchString(k) || !optionValue.MatchString(s) {
+			return nil, fmt.Errorf("option %s=%v is not an IPP option name and a plain value", k, val)
+		}
+		out[k] = s
+	}
+	return out, nil
+}
+
+// lpoptionsOf reads lpoptions' answer: name=value pairs, a value quoted with ' or with backslash escapes.
+func lpoptionsOf(s string) map[string]string {
+	out := map[string]string{}
+	s = strings.TrimSpace(s)
+	i := 0
+	for i < len(s) {
+		for i < len(s) && s[i] == ' ' {
+			i++
+		}
+		start := i
+		for i < len(s) && s[i] != '=' && s[i] != ' ' {
+			i++
+		}
+		key := s[start:i]
+		if i >= len(s) || s[i] != '=' {
+			if key != "" {
+				out[key] = ""
+			}
+			continue
+		}
+		i++
+		var b strings.Builder
+		for i < len(s) && s[i] != ' ' {
+			switch s[i] {
+			case '\'':
+				i++
+				for i < len(s) && s[i] != '\'' {
+					if s[i] == '\\' && i+1 < len(s) {
+						i++
+					}
+					b.WriteByte(s[i])
+					i++
+				}
+				i++
+			case '\\':
+				if i+1 < len(s) {
+					b.WriteByte(s[i+1])
+				}
+				i += 2
+			default:
+				b.WriteByte(s[i])
+				i++
+			}
+		}
+		out[key] = b.String()
+	}
+	return out
+}
+
+// Marker is one supply the printer reports.
+type Marker struct {
+	Name  string `json:"name"`
+	Type  string `json:"type,omitempty"`
+	Level int    `json:"level_percent"`
+	Low   bool   `json:"low"`
+}
+
+// Printer is one queue.
+type Printer struct {
+	Name       string   `json:"name"`
+	State      string   `json:"state"`
+	Enabled    bool     `json:"enabled"`
+	Accepting  bool     `json:"accepting"`
+	Default    bool     `json:"default"`
+	URI        string   `json:"uri"`
+	MakeModel  string   `json:"make_and_model"`
+	Driverless bool     `json:"driverless"`
+	Shared     bool     `json:"shared"`
+	Reasons    []string `json:"reasons"`
+	Markers    []Marker `json:"markers"`
+	Since      string   `json:"since,omitempty"`
+	Message    string   `json:"message,omitempty"`
+}
+
+// PrintersAnswer is what cups_printers answers.
+type PrintersAnswer struct {
+	Scheduler string    `json:"scheduler"`
+	Default   string    `json:"default,omitempty"`
+	Printers  []Printer `json:"printers"`
+}
+
+func lpstat(args ...string) (string, error) {
+	r, err := call(Cmd{Name: "lpstat", Args: args})
+	if err != nil {
+		if strings.Contains(r.Stderr, "Scheduler is not running") || strings.Contains(r.Stderr, "Connection refused") {
+			return "", fmt.Errorf("the print scheduler is not running on this machine: %s", firstLine(r.Stderr))
+		}
+		// lpstat answers "No destinations added." with a non-zero status: that is no printers.
+		if strings.Contains(r.Stderr, "No destinations added") {
+			return "", nil
+		}
+		return "", err
+	}
+	return r.Stdout, nil
+}
+
+func defaultPrinter() (string, error) {
+	out, err := lpstat("-d")
+	if err != nil {
+		return "", err
+	}
+	if _, after, ok := strings.Cut(out, "system default destination: "); ok {
+		return strings.TrimSpace(firstLine(after)), nil
+	}
+	return "", nil
+}
+
+// Printers answers every queue with its state, device, model and supplies.
+func Printers() (PrintersAnswer, error) {
+	out := PrintersAnswer{Printers: []Printer{}}
+	sched, err := lpstat("-r")
+	if err != nil {
+		return out, err
+	}
+	out.Scheduler = strings.TrimSpace(sched)
+	if out.Default, err = defaultPrinter(); err != nil {
+		return out, err
+	}
+	ps, err := lpstat("-p")
+	if err != nil {
+		return out, err
+	}
+	var cur *Printer
+	for _, l := range strings.Split(ps, "\n") {
+		if strings.HasPrefix(l, "printer ") {
+			f := strings.Fields(l)
+			if len(f) < 3 {
+				continue
+			}
+			out.Printers = append(out.Printers, Printer{Name: f[1], Reasons: []string{}, Markers: []Marker{}})
+			cur = &out.Printers[len(out.Printers)-1]
+			rest := strings.Join(f[2:], " ")
+			switch {
+			case strings.HasPrefix(rest, "is idle"):
+				cur.State = "idle"
+			case strings.HasPrefix(rest, "now printing"):
+				cur.State = "printing"
+			default:
+				cur.State = "stopped"
+			}
+			// "disabled since …" (stopped), or "enabled since …" after the state.
+			cur.Enabled = !strings.HasPrefix(rest, "disabled") && !strings.Contains(rest, "disabled since")
+			if _, since, found := strings.Cut(rest, " since "); found {
+				cur.Since = strings.TrimSuffix(strings.TrimSpace(since), " -")
+			}
+			continue
+		}
+		if cur != nil && strings.HasPrefix(l, "\t") && strings.TrimSpace(l) != "" {
+			cur.Message = strings.TrimSpace(cur.Message + " " + strings.TrimSpace(l))
+		}
+	}
+	acc, err := lpstat("-a")
+	if err != nil {
+		return out, err
+	}
+	accepting := map[string]bool{}
+	for _, l := range lines(acc) {
+		if f := strings.Fields(l); len(f) >= 2 && f[1] == "accepting" {
+			accepting[f[0]] = true
+		}
+	}
+	for i := range out.Printers {
+		p := &out.Printers[i]
+		p.Accepting = accepting[p.Name]
+		p.Default = p.Name == out.Default
+		r, err := call(Cmd{Name: "lpoptions", Args: []string{"-p", p.Name}})
+		if err != nil {
+			return out, err
+		}
+		o := lpoptionsOf(r.Stdout)
+		p.URI = o["device-uri"]
+		p.MakeModel = o["printer-make-and-model"]
+		p.Driverless = driverless(p.MakeModel, p.URI)
+		p.Shared = o["printer-is-shared"] == "true"
+		for _, reason := range strings.Split(o["printer-state-reasons"], ",") {
+			if reason = strings.TrimSpace(reason); reason != "" && reason != "none" {
+				p.Reasons = append(p.Reasons, reason)
+			}
+		}
+		p.Markers = markersOf(o)
+	}
+	return out, nil
+}
+
+// driverless says a queue prints without a vendor driver: CUPS's own IPP Everywhere model, or a
+// driverless URI.
+func driverless(model, uri string) bool {
+	m := strings.ToLower(model)
+	return strings.Contains(m, "ipp everywhere") || strings.Contains(m, "driverless") || strings.HasPrefix(uri, "implicitclass:") ||
+		strings.HasPrefix(uri, "ipp://") && strings.Contains(m, "everywhere")
+}
+
+func markersOf(o map[string]string) []Marker {
+	split := func(k string) []string {
+		if o[k] == "" {
+			return nil
+		}
+		return strings.Split(o[k], ",")
+	}
+	names, levels, lows, types := split("marker-names"), split("marker-levels"), split("marker-low-levels"), split("marker-types")
+	out := []Marker{}
+	for i, n := range names {
+		if i >= len(levels) {
+			break
+		}
+		level, err := strconv.Atoi(strings.TrimSpace(levels[i]))
+		if err != nil {
+			continue
+		}
+		m := Marker{Name: strings.TrimSpace(n), Level: level}
+		if i < len(types) {
+			m.Type = strings.TrimSpace(types[i])
+		}
+		if i < len(lows) {
+			if low, err := strconv.Atoi(strings.TrimSpace(lows[i])); err == nil && level >= 0 && level <= low {
+				m.Low = true
+			}
+		}
+		out = append(out, m)
+	}
+	return out
+}
+
+// Job is one print job.
+type Job struct {
+	ID        string `json:"id"`
+	Printer   string `json:"printer"`
+	User      string `json:"user"`
+	Bytes     int64  `json:"bytes"`
+	Submitted string `json:"submitted"`
+}
+
+// Queue answers the jobs waiting, or the finished ones.
+func Queue(printer string, completed bool, limit int) (map[string]any, error) {
+	args := []string{}
+	if completed {
+		args = append(args, "-W", "completed")
+	}
+	args = append(args, "-o")
+	if printer != "" {
+		if err := checkPrinter(printer); err != nil {
+			return nil, err
+		}
+		args = append(args, printer)
+	}
+	out, err := lpstat(args...)
+	if err != nil {
+		return nil, err
+	}
+	jobs := []Job{}
+	for _, l := range lines(out) {
+		f := strings.Fields(l)
+		if len(f) < 4 {
+			continue
+		}
+		i := strings.LastIndex(f[0], "-")
+		if i <= 0 {
+			continue
+		}
+		size, _ := strconv.ParseInt(f[2], 10, 64)
+		jobs = append(jobs, Job{ID: f[0], Printer: f[0][:i], User: f[1], Bytes: size, Submitted: strings.Join(f[3:], " ")})
+	}
+	sort.SliceStable(jobs, func(a, b int) bool { return jobNumber(jobs[a].ID) > jobNumber(jobs[b].ID) })
+	total := len(jobs)
+	if len(jobs) > limit {
+		jobs = jobs[:limit]
+	}
+	return map[string]any{"count": total, "jobs": jobs, "completed": completed}, nil
+}
+
+func jobNumber(id string) int {
+	n, _ := strconv.Atoi(id[strings.LastIndex(id, "-")+1:])
+	return n
+}
+
+var jobID = regexp.MustCompile(`^([A-Za-z0-9_.@-]+-)?[0-9]+$`)
+
+// refused says CUPS kept an act for its administrators.
+func refused(r Result) bool {
+	s := r.Stderr + r.Stdout
+	return strings.Contains(s, "Forbidden") || strings.Contains(s, "not-authorized") || strings.Contains(s, "Not authorized") || strings.Contains(s, "not allowed")
+}
+
+// asAccountThenRoot runs an act as the account, and through sudo -n when CUPS refuses the account.
+func asAccountThenRoot(c Cmd) (Result, bool, error) {
+	r := run(c)
+	if r.Status == 0 && r.Error == "" {
+		return r, false, nil
+	}
+	if !refused(r) {
+		return r, false, failure(c, r)
+	}
+	c.Root = true
+	r, err := call(c)
+	return r, true, err
+}
+
+// Cancel cancels one job, or every job on a printer.
+func Cancel(job, printer string, all bool) (map[string]any, error) {
+	var c Cmd
+	switch {
+	case all:
+		if printer == "" {
+			return nil, fmt.Errorf("all needs printer: cancelling every job on every printer is not offered")
+		}
+		if err := checkPrinter(printer); err != nil {
+			return nil, err
+		}
+		c = Cmd{Name: "cancel", Args: []string{"-a", printer}}
+	case job != "":
+		if !jobID.MatchString(job) {
+			return nil, fmt.Errorf("%q is not a job id", job)
+		}
+		c = Cmd{Name: "cancel", Args: []string{job}}
+	default:
+		return nil, fmt.Errorf("give job, or printer with all")
+	}
+	_, escalated, err := asAccountThenRoot(c)
+	if err != nil {
+		return nil, err
+	}
+	return map[string]any{"cancelled": strings.Join(c.Args, " "), "as_root": escalated}, nil
+}
+
+var requestID = regexp.MustCompile(`request id is (\S+)`)
+
+// statFile tells a regular file. Tests replace it.
+var statFile = func(p string) error {
+	info, err := os.Stat(p)
+	if err != nil {
+		return err
+	}
+	if !info.Mode().IsRegular() {
+		return fmt.Errorf("%s is not a regular file", p)
+	}
+	return nil
+}
+
+// Print sends a file to a printer.
+func Print(file, printer string, copies int, opts map[string]string, title string) (map[string]any, error) {
+	if !filepath.IsAbs(file) {
+		return nil, fmt.Errorf("file must be an absolute path, not %q", file)
+	}
+	if err := statFile(file); err != nil {
+		return nil, fmt.Errorf("cannot print %s: %v", file, err)
+	}
+	args := []string{}
+	if printer != "" {
+		if err := checkPrinter(printer); err != nil {
+			return nil, err
+		}
+		args = append(args, "-d", printer)
+	}
+	args = append(args, "-n", strconv.Itoa(copies))
+	names := make([]string, 0, len(opts))
+	for k := range opts {
+		names = append(names, k)
+	}
+	sort.Strings(names)
+	for _, k := range names {
+		args = append(args, "-o", k+"="+opts[k])
+	}
+	if title == "" {
+		title = filepath.Base(file)
+	}
+	args = append(args, "-t", title, "--", file)
+	r, err := call(Cmd{Name: "lp", Args: args})
+	if err != nil {
+		if strings.Contains(r.Stderr, "No default destination") {
+			return nil, fmt.Errorf("no printer given and this machine has no default printer: name one, or set one with cups_default")
+		}
+		return nil, err
+	}
+	m := requestID.FindStringSubmatch(r.Stdout)
+	if m == nil {
+		return nil, fmt.Errorf("lp answered no job id: %s", strings.TrimSpace(r.Stdout+r.Stderr))
+	}
+	return map[string]any{"job": m[1], "file": file, "copies": copies, "follow": "cups_queue"}, nil
+}
+
+// Default answers the default printer, or sets it.
+func Default(printer string) (map[string]any, error) {
+	if printer == "" {
+		d, err := defaultPrinter()
+		if err != nil {
+			return nil, err
+		}
+		return map[string]any{"default": d}, nil
+	}
+	if err := checkPrinter(printer); err != nil {
+		return nil, err
+	}
+	was, err := defaultPrinter()
+	if err != nil {
+		return nil, err
+	}
+	if _, err := call(Cmd{Name: "lpadmin", Args: []string{"-d", printer}, Root: true}); err != nil {
+		return nil, err
+	}
+	return map[string]any{"default": printer, "was": was}, nil
+}
+
+// Resume enables a printer and makes it accept jobs.
+func Resume(printer string) (map[string]any, error) {
+	if err := checkPrinter(printer); err != nil {
+		return nil, err
+	}
+	for _, c := range []string{"cupsenable", "cupsaccept"} {
+		if _, err := call(Cmd{Name: c, Args: []string{printer}, Root: true}); err != nil {
+			return nil, err
+		}
+	}
+	return map[string]any{"printer": printer, "enabled": true, "accepting": true}, nil
+}
+
+// DriverPackage is a package that brings filters or backends.
+type DriverPackage struct {
+	Package string `json:"package"`
+	Version string `json:"version"`
+	Foreign bool   `json:"foreign"`
+}
+
+// Model is one driver model CUPS offers.
+type Model struct {
+	PPD         string `json:"ppd"`
+	Description string `json:"description"`
+}
+
+// QueueDriver is how one queue prints.
+type QueueDriver struct {
+	Printer    string `json:"printer"`
+	MakeModel  string `json:"make_and_model"`
+	Driverless bool   `json:"driverless"`
+	URI        string `json:"uri"`
+}
+
+// DriversAnswer is what cups_drivers answers.
+type DriversAnswer struct {
+	Queues   []QueueDriver   `json:"queues"`
+	Packages []DriverPackage `json:"driver_packages"`
+	Models   []Model         `json:"models"`
+	Matched  int             `json:"models_matched"`
+	Findings []string        `json:"findings"`
+}
+
+// driverDirs are where drivers put what CUPS runs.
+var driverDirs = []string{"/usr/lib/cups/filter", "/usr/lib/cups/backend"}
+
+// basePackages bring CUPS's own filters and backends, not a printer's driver.
+var basePackages = map[string]bool{"cups": true, "cups-filters": true, "libcups": true, "ghostscript": true, "cups-pdf": false}
+
+// Drivers answers how each queue prints and which packages bring drivers.
+func Drivers(match string, limit int) (DriversAnswer, error) {
+	out := DriversAnswer{Queues: []QueueDriver{}, Packages: []DriverPackage{}, Models: []Model{}, Findings: []string{}}
+	ps, err := Printers()
+	if err != nil {
+		return out, err
+	}
+	for _, p := range ps.Printers {
+		out.Queues = append(out.Queues, QueueDriver{Printer: p.Name, MakeModel: p.MakeModel, Driverless: p.Driverless, URI: p.URI})
+	}
+	r := run(Cmd{Name: "pacman", Args: append([]string{"-Qo"}, driverDirs...)})
+	if r.Error != "" {
+		return out, failure(Cmd{Name: "pacman", Args: []string{"-Qo"}}, r)
+	}
+	seen := map[string]bool{}
+	for _, l := range lines(r.Stdout) {
+		if _, after, ok := strings.Cut(l, " is owned by "); ok {
+			f := strings.Fields(after)
+			if len(f) >= 2 && !seen[f[0]] && !basePackages[f[0]] {
+				seen[f[0]] = true
+				out.Packages = append(out.Packages, DriverPackage{Package: f[0], Version: f[1]})
+			}
+		}
+	}
+	if len(out.Packages) > 0 {
+		r := run(Cmd{Name: "pacman", Args: []string{"-Qqm"}})
+		foreign := map[string]bool{}
+		for _, l := range lines(r.Stdout) {
+			foreign[strings.TrimSpace(l)] = true
+		}
+		for i := range out.Packages {
+			out.Packages[i].Foreign = foreign[out.Packages[i].Package]
+		}
+	}
+	sort.Slice(out.Packages, func(i, k int) bool { return out.Packages[i].Package < out.Packages[k].Package })
+	m, err := call(Cmd{Name: "lpinfo", Args: []string{"-m"}})
+	if err != nil {
+		return out, err
+	}
+	for _, l := range lines(m.Stdout) {
+		ppd, desc, _ := strings.Cut(l, " ")
+		if match != "" && !strings.Contains(strings.ToLower(desc), strings.ToLower(match)) && !strings.Contains(strings.ToLower(ppd), strings.ToLower(match)) {
+			continue
+		}
+		out.Matched++
+		if len(out.Models) < limit {
+			out.Models = append(out.Models, Model{PPD: ppd, Description: desc})
+		}
+	}
+	// Which driver packages no queue prints through.
+	allDriverless := len(out.Queues) > 0
+	for _, q := range out.Queues {
+		allDriverless = allDriverless && q.Driverless
+	}
+	for _, p := range out.Packages {
+		if p.Foreign {
+			out.Findings = append(out.Findings, "driver package "+p.Package+" is not from the official repositories")
+		}
+		if allDriverless {
+			out.Findings = append(out.Findings, "every queue prints driverless, so no queue uses the driver package "+p.Package)
+		}
+	}
+	return out, nil
+}

modules/cups/cmd/cups-tools/cups_test.go

@@ -0,0 +1,234 @@
+package main
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestTheManifestIsTheSchedulerAndDriverlessPrintingAndNoVendorDriver(t *testing.T) {
+	m := readManifest(t)
+	holdsTheBundle(t, m, "cups")
+	if got := strings.Join(m.packages(), ","); got != "cups,cups-filters" {
+		t.Errorf("packages %s: a vendor driver is from outside the official repositories, and no queue measured needs one but the desktop's Canon", got)
+	}
+	s := m.services()
+	for _, u := range []string{"cups.socket", "cups.service"} {
+		if s[u] == nil || s[u]["state"] != "running" || s[u]["boot"] != "enabled" {
+			t.Errorf("%s: %v", u, s[u])
+		}
+	}
+	for _, r := range m.Resources {
+		if r["type"] == "file" {
+			t.Errorf("the queues and cupsd's files are CUPS's own: %v", r["id"])
+		}
+	}
+}
+
+// The desktop's two queues on 2026-10-04.
+func theDesktop(t *testing.T, more func(line string, c Cmd) (Result, bool)) *fake {
+	return using(t, func(line string, c Cmd) Result {
+		if more != nil {
+			if r, handled := more(line, c); handled {
+				return r
+			}
+		}
+		switch line {
+		case "lpstat -r":
+			return ok("scheduler is running\n")
+		case "lpstat -d":
+			return ok("system default destination: Brother_MFC_Novox\n")
+		case "lpstat -p":
+			return ok("printer Brother_MFC_Novox is idle.  enabled since Mon Jun 29 21:34:30 2026\n" +
+				"printer Kanjuro disabled since Sun Jun  9 11:16:03 2024 -\n\tPaused\n")
+		case "lpstat -a":
+			return ok("Brother_MFC_Novox accepting requests since Mon Jun 29 21:34:30 2026\nKanjuro not accepting requests since Sun Jun  9 11:16:03 2024 -\n\tRejecting Jobs\n")
+		case "lpoptions -p Brother_MFC_Novox":
+			return ok(`copies=1 device-uri=ipp://192.0.2.171/ipp/port1 finishings=3 marker-levels=70,100,8,100 marker-low-levels=10,10,10,10 marker-names='Black\ Toner\ Cartridge,Cyan\ Toner\ Cartridge,Magenta\ Toner\ Cartridge,Yellow\ Toner\ Cartridge' marker-types=toner,toner,toner,toner printer-is-shared=false printer-make-and-model='Printer - IPP Everywhere' printer-state-reasons=none`)
+		case "lpoptions -p Kanjuro":
+			return ok(`device-uri=cnijnet:/18-0C-AC-B0-62-83 printer-is-shared=false printer-make-and-model='Canon MG4200 series Ver.3.80' printer-state-reasons=paused`)
+		}
+		return Result{Status: 9, Stderr: "unexpected " + line}
+	})
+}
+
+func TestPrintersReadsStateDeviceModelAndSupplies(t *testing.T) {
+	theDesktop(t, nil)
+	got, err := Printers()
+	if err != nil || len(got.Printers) != 2 || got.Default != "Brother_MFC_Novox" || got.Scheduler != "scheduler is running" {
+		t.Fatalf("%+v %v", got, err)
+	}
+	b, k := got.Printers[0], got.Printers[1]
+	if b.State != "idle" || !b.Enabled || !b.Accepting || !b.Default || !b.Driverless || b.URI != "ipp://192.0.2.171/ipp/port1" || len(b.Reasons) != 0 {
+		t.Errorf("%+v", b)
+	}
+	if len(b.Markers) != 4 || b.Markers[0].Name != "Black Toner Cartridge" || b.Markers[2].Level != 8 || !b.Markers[2].Low || b.Markers[0].Low {
+		t.Errorf("markers %+v", b.Markers)
+	}
+	if k.State != "stopped" || k.Enabled || k.Accepting || k.Driverless || strings.Join(k.Reasons, ",") != "paused" || k.Message != "Paused" {
+		t.Errorf("%+v", k)
+	}
+}
+
+func TestPrintersWithoutAQueueOrAScheduler(t *testing.T) {
+	using(t, func(line string, c Cmd) Result {
+		if line == "lpstat -r" {
+			return ok("scheduler is running\n")
+		}
+		return Result{Status: 1, Stderr: "lpstat: No destinations added.\n"}
+	})
+	got, err := Printers()
+	if err != nil || len(got.Printers) != 0 {
+		t.Fatalf("no queue is an empty answer, not a failure: %+v %v", got, err)
+	}
+	using(t, func(string, Cmd) Result { return Result{Status: 1, Stderr: "lpstat: Scheduler is not running.\n"} })
+	if _, err := Printers(); err == nil || !strings.Contains(err.Error(), "scheduler is not running") {
+		t.Fatalf("%v", err)
+	}
+}
+
+func TestLpoptionsQuotingIsRead(t *testing.T) {
+	o := lpoptionsOf(`a=1 b='x y' c=p\ q d e=`)
+	if o["a"] != "1" || o["b"] != "x y" || o["c"] != "p q" || o["d"] != "" || o["e"] != "" {
+		t.Errorf("%v", o)
+	}
+}
+
+func TestQueueReadsJobsNewestFirstAndBounded(t *testing.T) {
+	f := using(t, func(string, Cmd) Result {
+		return ok("Brother-6               jochen            1024   Mon Jul  8 12:15:34 2024\nBrother-8               jochen            2048   Mon Jul  8 12:19:56 2024\nBrother-7               other             1024   Mon Jul  8 12:15:23 2024\n")
+	})
+	got, err := Queue("Brother", true, 2)
+	jobs := got["jobs"].([]Job)
+	if err != nil || got["count"] != 3 || len(jobs) != 2 || jobs[0].ID != "Brother-8" || jobs[0].Printer != "Brother" || jobs[0].Bytes != 2048 || jobs[0].Submitted != "Mon Jul 8 12:19:56 2024" {
+		t.Fatalf("%+v %v", got, err)
+	}
+	if f.lines()[0] != "lpstat -W completed -o Brother" {
+		t.Errorf("%v", f.lines())
+	}
+	if _, err := Queue("-h", false, 5); err == nil {
+		t.Error("an option as a printer")
+	}
+}
+
+func TestCancelTriesTheAccountThenRootWhenCUPSRefusesIt(t *testing.T) {
+	f := using(t, func(line string, c Cmd) Result {
+		if !strings.HasPrefix(line, "sudo") {
+			return Result{Status: 1, Stderr: "cancel: Forbidden\n"}
+		}
+		return ok("")
+	})
+	got, err := Cancel("Brother-12", "", false)
+	if err != nil || got["as_root"] != true {
+		t.Fatalf("%v %v", got, err)
+	}
+	if strings.Join(f.lines(), "|") != "cancel Brother-12|sudo -n cancel Brother-12" {
+		t.Errorf("%v", f.lines())
+	}
+	f = using(t, func(string, Cmd) Result { return ok("") })
+	if got, err := Cancel("", "Brother", true); err != nil || got["as_root"] != false || f.lines()[0] != "cancel -a Brother" {
+		t.Fatalf("%v %v %v", got, err, f.lines())
+	}
+	using(t, func(string, Cmd) Result { return Result{Status: 1, Stderr: "cancel: Unknown job 99\n"} })
+	if _, err := Cancel("99", "", false); err == nil || !strings.Contains(err.Error(), "Unknown job") {
+		t.Errorf("a failure that is not a refusal is not retried as root: %v", err)
+	}
+	for _, bad := range [][3]string{{"", "", ""}, {"12; rm", "", ""}, {"", "", "all"}} {
+		if _, err := Cancel(bad[0], bad[1], bad[2] == "all"); err == nil {
+			t.Errorf("%v accepted", bad)
+		}
+	}
+}
+
+func TestPrintChecksTheFileAndOptionsAndAnswersTheJob(t *testing.T) {
+	was := statFile
+	defer func() { statFile = was }()
+	statFile = func(p string) error {
+		if p == "/home/op/doc.pdf" {
+			return nil
+		}
+		return errString("no such file")
+	}
+	f := using(t, func(string, Cmd) Result { return ok("request id is Brother-13 (1 file(s))\n") })
+	got, err := Print("/home/op/doc.pdf", "Brother", 2, map[string]string{"sides": "two-sided-long-edge", "media": "A4"}, "")
+	if err != nil || got["job"] != "Brother-13" {
+		t.Fatalf("%v %v", got, err)
+	}
+	if l := f.lines()[0]; l != "lp -d Brother -n 2 -o media=A4 -o sides=two-sided-long-edge -t doc.pdf -- /home/op/doc.pdf" {
+		t.Errorf("%s", l)
+	}
+	if _, err := Print("doc.pdf", "", 1, nil, ""); err == nil {
+		t.Error("a relative file")
+	}
+	if _, err := Print("/home/op/missing.pdf", "", 1, nil, ""); err == nil {
+		t.Error("a missing file")
+	}
+	if _, err := optionsOf(map[string]any{"options": map[string]any{"sides": "x y"}}); err == nil {
+		t.Error("an option value with a space")
+	}
+	if _, err := optionsOf(map[string]any{"options": map[string]any{"-o": "x"}}); err == nil {
+		t.Error("an option name that is an option")
+	}
+	using(t, func(string, Cmd) Result { return Result{Status: 1, Stderr: "lp: Error - No default destination."} })
+	if _, err := Print("/home/op/doc.pdf", "", 1, nil, ""); err == nil || !strings.Contains(err.Error(), "no default printer") {
+		t.Errorf("%v", err)
+	}
+}
+
+type errString string
+
+func (e errString) Error() string { return string(e) }
+
+func TestDefaultReadsAndSetsThroughSudo(t *testing.T) {
+	f := theDesktop(t, func(line string, c Cmd) (Result, bool) {
+		if strings.HasPrefix(line, "sudo -n lpadmin") {
+			return ok(""), true
+		}
+		return Result{}, false
+	})
+	got, err := Default("")
+	if err != nil || got["default"] != "Brother_MFC_Novox" {
+		t.Fatalf("%v %v", got, err)
+	}
+	got, err = Default("Kanjuro")
+	if err != nil || got["default"] != "Kanjuro" || got["was"] != "Brother_MFC_Novox" {
+		t.Fatalf("%v %v", got, err)
+	}
+	if l := f.lines(); l[len(l)-1] != "sudo -n lpadmin -d Kanjuro" {
+		t.Errorf("%v", l)
+	}
+}
+
+func TestResumeEnablesAndAcceptsThroughSudo(t *testing.T) {
+	f := using(t, func(string, Cmd) Result { return ok("") })
+	if _, err := Resume("Kanjuro"); err != nil {
+		t.Fatal(err)
+	}
+	if strings.Join(f.lines(), "|") != "sudo -n cupsenable Kanjuro|sudo -n cupsaccept Kanjuro" {
+		t.Errorf("%v", f.lines())
+	}
+}
+
+func TestDriversNamesForeignDriverPackagesAndOnesNoQueueUses(t *testing.T) {
+	theDesktop(t, func(line string, c Cmd) (Result, bool) {
+		switch {
+		case strings.HasPrefix(line, "pacman -Qo"):
+			return ok("/usr/lib/cups/filter/ is owned by brother-mfc-l8390cdw 3.5.1-2\n/usr/lib/cups/filter/ is owned by cups 2:2.4.19-1\n/usr/lib/cups/filter/ is owned by cups-filters 2.0.1-2\n/usr/lib/cups/backend/ is owned by cnijfilter-mg4200 3.80-6\n/usr/lib/cups/backend/ is owned by cups 2:2.4.19-1\n"), true
+		case line == "pacman -Qqm":
+			return ok("brother-mfc-l8390cdw\ncnijfilter-mg4200\nsnapd\n"), true
+		case line == "lpinfo -m":
+			return ok("drv:///sample.drv/dymo.ppd DYMO Label Printer\ncanonmg4200.ppd Canon MG4200 series Ver.3.80\neverywhere IPP Everywhere\n"), true
+		}
+		return Result{}, false
+	})
+	got, err := Drivers("canon", 10)
+	if err != nil || len(got.Queues) != 2 || len(got.Packages) != 2 || got.Matched != 1 || got.Models[0].PPD != "canonmg4200.ppd" {
+		t.Fatalf("%+v %v", got, err)
+	}
+	if !got.Packages[0].Foreign || got.Packages[0].Package != "brother-mfc-l8390cdw" {
+		t.Errorf("%+v", got.Packages)
+	}
+	all := strings.Join(got.Findings, ";")
+	if !strings.Contains(all, "cnijfilter-mg4200 is not from the official") || strings.Contains(all, "every queue prints driverless") {
+		t.Errorf("the Canon queue uses its driver, so not every queue is driverless: %s", all)
+	}
+}

modules/cups/cmd/cups-tools/kit.go

@@ -0,0 +1,352 @@
+package main
+
+// kit.go is the same file in each of the workstations' tool bundles (fonts, docker-compose, snapd,
+// flatpak, cups, bluetooth, xclip, dmenu): how a tool runs a command, escalates, bounds what it
+// keeps, and names a failure. A module is built from its own directory, so the file is copied rather
+// than shared; a change to one copy is made to all eight.
+//
+// The rules it holds (novox/hq research 026/05, to-be 38 WP4):
+//   - the node's tool runtime runs as the operator account, not root (ADR 0175 §4); a command that
+//     needs root goes through `sudo -n`, never a prompt, and a refusal is named as such;
+//   - one command gets 20 s, below the runtime's 30 s call limit, and is ended with everything it
+//     started when it takes longer;
+//   - each stream is kept to 256 KiB, and the answer says when it was cut;
+//   - a failure is an error with what went wrong in it, never an empty answer.
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"strings"
+	"syscall"
+	"time"
+)
+
+// Bounds every command is held to.
+const (
+	CallTimeout = 20 * time.Second
+	MostOutput  = 256 << 10
+)
+
+// Cmd is one command a tool runs.
+type Cmd struct {
+	Name string
+	Args []string
+	// Stdin is written to the command's standard input when not empty.
+	Stdin string
+	// Env is added to this process's own environment.
+	Env []string
+	// Root says the command needs root: it is run through `sudo -n` when this process is not root.
+	Root bool
+	// Timeout replaces CallTimeout; only a background job (jobs.go) asks for longer.
+	Timeout time.Duration
+	// Detached is for a program that forks a child which outlives it, as xclip does to keep the
+	// selection: its streams go to files, because a pipe the child inherits would hold the call open
+	// until the child exits.
+	Detached bool
+}
+
+// Result is what a command did.
+type Result struct {
+	Stdout string `json:"stdout"`
+	Stderr string `json:"stderr"`
+	Status int    `json:"status"`
+	// Error is why it did not run to an answer: "not-found" when the program is not there,
+	// "timeout" when it was ended for taking too long, else the spawn error.
+	Error     string `json:"error,omitempty"`
+	Truncated bool   `json:"truncated,omitempty"`
+}
+
+// Runner runs a command. Tests replace it; nothing else does.
+type Runner func(Cmd) Result
+
+var (
+	run  Runner = execRun
+	euid        = os.Geteuid
+)
+
+// argv is the command as it is run: through sudo without a prompt when it needs root and this
+// process is not root.
+func argv(c Cmd) (string, []string) {
+	if c.Root && euid() != 0 {
+		return "sudo", append([]string{"-n", c.Name}, c.Args...)
+	}
+	return c.Name, c.Args
+}
+
+// bounded keeps the first MostOutput bytes written to it and notes that more came.
+type bounded struct {
+	b   bytes.Buffer
+	cut bool
+}
+
+func (w *bounded) Write(p []byte) (int, error) {
+	room := MostOutput - w.b.Len()
+	if room <= 0 {
+		w.cut = w.cut || len(p) > 0
+		return len(p), nil
+	}
+	if len(p) > room {
+		w.b.Write(p[:room])
+		w.cut = true
+		return len(p), nil
+	}
+	return w.b.Write(p)
+}
+
+func execRun(c Cmd) Result {
+	timeout := c.Timeout
+	if timeout <= 0 {
+		timeout = CallTimeout
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), timeout)
+	defer cancel()
+	name, args := argv(c)
+	cmd := exec.CommandContext(ctx, name, args...)
+	cmd.Env = append(append(os.Environ(), "LC_ALL=C"), c.Env...)
+	if !c.Detached {
+		// Its own process group, so that ending it on a timeout ends what it started too.
+		cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+		cmd.Cancel = func() error {
+			if cmd.Process != nil {
+				_ = syscall.Kill(-cmd.Process.Pid, syscall.SIGKILL)
+			}
+			return nil
+		}
+	}
+	cmd.WaitDelay = 2 * time.Second
+	if c.Stdin != "" {
+		cmd.Stdin = strings.NewReader(c.Stdin)
+	}
+	var out, errs bounded
+	var outFile, errFile *os.File
+	if c.Detached {
+		var err error
+		if outFile, err = os.CreateTemp("", "mesh-tool-out-*"); err != nil {
+			return Result{Status: 127, Error: err.Error()}
+		}
+		defer os.Remove(outFile.Name())
+		defer outFile.Close()
+		if errFile, err = os.CreateTemp("", "mesh-tool-err-*"); err != nil {
+			return Result{Status: 127, Error: err.Error()}
+		}
+		defer os.Remove(errFile.Name())
+		defer errFile.Close()
+		cmd.Stdout, cmd.Stderr = outFile, errFile
+	} else {
+		cmd.Stdout, cmd.Stderr = &out, &errs
+	}
+	err := cmd.Run()
+	if c.Detached {
+		for _, f := range []struct {
+			file *os.File
+			into *bounded
+		}{{outFile, &out}, {errFile, &errs}} {
+			if _, e := f.file.Seek(0, io.SeekStart); e == nil {
+				_, _ = io.Copy(f.into, f.file)
+			}
+		}
+	}
+	r := Result{Stdout: out.b.String(), Stderr: errs.b.String(), Truncated: out.cut || errs.cut}
+	var exit *exec.ExitError
+	switch {
+	case err == nil:
+	case ctx.Err() == context.DeadlineExceeded:
+		r.Status, r.Error = 124, "timeout"
+	case errors.Is(err, exec.ErrNotFound) || errors.Is(err, os.ErrNotExist):
+		r.Status, r.Error = 127, "not-found"
+	case errors.As(err, &exit):
+		r.Status = exit.ExitCode()
+	default:
+		r.Status, r.Error = 127, err.Error()
+	}
+	return r
+}
+
+// call runs a command and answers its result, or an error naming what went wrong.
+func call(c Cmd) (Result, error) {
+	r := run(c)
+	if r.Status == 0 && r.Error == "" {
+		return r, nil
+	}
+	return r, failure(c, r)
+}
+
+// failure names how a command failed: not installed, refused escalation, too slow, or its exit
+// status with the end of what it said.
+func failure(c Cmd, r Result) error {
+	program, _ := argv(c)
+	switch {
+	case r.Error == "not-found" && program == "sudo":
+		return fmt.Errorf("%s needs root, and sudo is not installed here for the runtime's account to escalate with", c.Name)
+	case r.Error == "not-found":
+		if hint, ok := providedBy[c.Name]; ok {
+			return fmt.Errorf("%s is not installed on this machine (%s)", c.Name, hint)
+		}
+		return fmt.Errorf("%s is not installed on this machine", c.Name)
+	case r.Error == "timeout":
+		limit := c.Timeout
+		if limit <= 0 {
+			limit = CallTimeout
+		}
+		return fmt.Errorf("%s gave no answer within %s and was ended", c.Name, limit)
+	case r.Error != "":
+		return fmt.Errorf("%s did not run: %s", c.Name, r.Error)
+	case program == "sudo" && strings.Contains(r.Stderr, "command not found"):
+		if hint, ok := providedBy[c.Name]; ok {
+			return fmt.Errorf("%s is not installed on this machine (%s)", c.Name, hint)
+		}
+		return fmt.Errorf("%s is not installed on this machine", c.Name)
+	case program == "sudo" && strings.HasPrefix(strings.TrimSpace(r.Stderr), "sudo:"):
+		return fmt.Errorf("%s needs root, and sudo -n refused the runtime's account: %s (the escalation is the sudo module's to declare)",
+			c.Name, firstLine(r.Stderr))
+	}
+	said := tail(strings.TrimSpace(r.Stderr), 2000)
+	if said == "" {
+		said = tail(strings.TrimSpace(r.Stdout), 2000)
+	}
+	if said == "" {
+		said = "and said nothing"
+	}
+	return fmt.Errorf("%s %s exited %d: %s", c.Name, strings.Join(c.Args, " "), r.Status, said)
+}
+
+func firstLine(s string) string {
+	s = strings.TrimSpace(s)
+	if i := strings.IndexByte(s, '\n'); i >= 0 {
+		return s[:i]
+	}
+	return s
+}
+
+func tail(s string, n int) string {
+	if len(s) <= n {
+		return s
+	}
+	return "…" + s[len(s)-n:]
+}
+
+// lines are a command's output lines, blank ones dropped.
+func lines(s string) []string {
+	out := []string{}
+	for _, l := range strings.Split(s, "\n") {
+		if strings.TrimSpace(l) != "" {
+			out = append(out, strings.TrimRight(l, "\r"))
+		}
+	}
+	return out
+}
+
+// Arguments, read the way a tool's JSON arguments arrive.
+
+func text(args map[string]any, key string) (string, error) {
+	v, ok := args[key]
+	if !ok || v == nil {
+		return "", fmt.Errorf("%s is required", key)
+	}
+	s, ok := v.(string)
+	if !ok {
+		return "", fmt.Errorf("%s must be a string", key)
+	}
+	if strings.TrimSpace(s) == "" {
+		return "", fmt.Errorf("%s must not be empty", key)
+	}
+	return s, nil
+}
+
+func optText(args map[string]any, key, def string) (string, error) {
+	v, ok := args[key]
+	if !ok || v == nil {
+		return def, nil
+	}
+	s, ok := v.(string)
+	if !ok {
+		return "", fmt.Errorf("%s must be a string", key)
+	}
+	if strings.TrimSpace(s) == "" {
+		return def, nil
+	}
+	return s, nil
+}
+
+// optWhole reads a whole number, defaulted, refused below least and held to most.
+func optWhole(args map[string]any, key string, def, least, most int) (int, error) {
+	v, ok := args[key]
+	if !ok || v == nil {
+		return def, nil
+	}
+	f, ok := v.(float64)
+	if !ok {
+		if i, isInt := v.(int); isInt {
+			f = float64(i)
+		} else {
+			return 0, fmt.Errorf("%s must be a number", key)
+		}
+	}
+	if f != float64(int(f)) {
+		return 0, fmt.Errorf("%s must be a whole number", key)
+	}
+	n := int(f)
+	if n < least {
+		return 0, fmt.Errorf("%s must be at least %d", key, least)
+	}
+	if n > most {
+		n = most
+	}
+	return n, nil
+}
+
+func optFlag(args map[string]any, key string, def bool) (bool, error) {
+	v, ok := args[key]
+	if !ok || v == nil {
+		return def, nil
+	}
+	b, ok := v.(bool)
+	if !ok {
+		return false, fmt.Errorf("%s must be true or false", key)
+	}
+	return b, nil
+}
+
+func optList(args map[string]any, key string) ([]string, error) {
+	v, ok := args[key]
+	if !ok || v == nil {
+		return nil, nil
+	}
+	items, ok := v.([]any)
+	if !ok {
+		return nil, fmt.Errorf("%s must be a list of strings", key)
+	}
+	out := make([]string, 0, len(items))
+	for _, it := range items {
+		s, ok := it.(string)
+		if !ok || strings.TrimSpace(s) == "" {
+			return nil, fmt.Errorf("%s must be a list of non-empty strings", key)
+		}
+		out = append(out, s)
+	}
+	return out, nil
+}
+
+// oneOf refuses a value outside a closed set.
+func oneOf(key, value string, allowed ...string) error {
+	for _, a := range allowed {
+		if value == a {
+			return nil
+		}
+	}
+	return fmt.Errorf("%s must be one of %s, not %q", key, strings.Join(allowed, ", "), value)
+}
+
+// plainName refuses a name that could be read as an option or carries a path or a space: package,
+// snap, application and printer names never do.
+func plainName(key, value string) error {
+	if strings.HasPrefix(value, "-") || strings.ContainsAny(value, " \t\n/\\") {
+		return fmt.Errorf("%s %q is not a plain name", key, value)
+	}
+	return nil
+}

modules/cups/cmd/cups-tools/kit_test.go

@@ -0,0 +1,147 @@
+package main
+
+// Tests of kit.go, the same in each workstation module.
+
+import (
+	"strings"
+	"testing"
+	"time"
+)
+
+// fake records the commands asked and answers each from a function of the command line.
+type fake struct {
+	asked  []Cmd
+	answer func(line string, c Cmd) Result
+}
+
+func (f *fake) runner() Runner {
+	return func(c Cmd) Result {
+		f.asked = append(f.asked, c)
+		name, args := argv(c)
+		line := strings.TrimSpace(name + " " + strings.Join(args, " "))
+		if f.answer == nil {
+			return Result{}
+		}
+		return f.answer(line, c)
+	}
+}
+
+func (f *fake) lines() []string {
+	out := []string{}
+	for _, c := range f.asked {
+		name, args := argv(c)
+		out = append(out, strings.TrimSpace(name+" "+strings.Join(args, " ")))
+	}
+	return out
+}
+
+// using installs a fake runner and a non-root uid for one test.
+func using(t *testing.T, answer func(line string, c Cmd) Result) *fake {
+	t.Helper()
+	f := &fake{answer: answer}
+	wasRun, wasUID := run, euid
+	run, euid = f.runner(), func() int { return 1000 }
+	t.Cleanup(func() { run, euid = wasRun, wasUID })
+	return f
+}
+
+func ok(stdout string) Result { return Result{Stdout: stdout} }
+
+func TestKitAnActThatNeedsRootGoesThroughSudoWithoutAPromptUnlessAlreadyRoot(t *testing.T) {
+	was := euid
+	defer func() { euid = was }()
+	euid = func() int { return 1000 }
+	if name, args := argv(Cmd{Name: "x", Args: []string{"a"}, Root: true}); name != "sudo" || strings.Join(args, " ") != "-n x a" {
+		t.Fatalf("not root: %s %v", name, args)
+	}
+	if name, _ := argv(Cmd{Name: "x"}); name != "x" {
+		t.Fatalf("a read is run as the account: %s", name)
+	}
+	euid = func() int { return 0 }
+	if name, _ := argv(Cmd{Name: "x", Root: true}); name != "x" {
+		t.Fatalf("as root no sudo: %s", name)
+	}
+}
+
+func TestKitAFailureIsNamedByHowItFailed(t *testing.T) {
+	was := euid
+	defer func() { euid = was }()
+	euid = func() int { return 1000 }
+	cases := []struct {
+		c    Cmd
+		r    Result
+		want string
+	}{
+		{Cmd{Name: "nothere"}, Result{Status: 127, Error: "not-found"}, "not installed"},
+		{Cmd{Name: "x", Root: true}, Result{Status: 127, Error: "not-found"}, "sudo is not installed"},
+		{Cmd{Name: "x", Root: true}, Result{Status: 1, Stderr: "sudo: a password is required\n"}, "sudo -n refused"},
+		{Cmd{Name: "x", Root: true}, Result{Status: 1, Stderr: "sudo: x: command not found\n"}, "x is not installed"},
+		{Cmd{Name: "x"}, Result{Status: 124, Error: "timeout"}, "within 20s"},
+		{Cmd{Name: "x", Args: []string{"y"}}, Result{Status: 3, Stderr: "boom\n"}, "x y exited 3: boom"},
+		{Cmd{Name: "x"}, Result{Status: 3}, "said nothing"},
+	}
+	for _, k := range cases {
+		err := failure(k.c, k.r)
+		if err == nil || !strings.Contains(err.Error(), k.want) {
+			t.Errorf("%+v: %v, want %q", k.r, err, k.want)
+		}
+	}
+}
+
+func TestKitOutputIsBoundedAndSaysSo(t *testing.T) {
+	var w bounded
+	big := strings.Repeat("a", MostOutput+10)
+	n, _ := w.Write([]byte(big))
+	if n != len(big) || w.b.Len() != MostOutput || !w.cut {
+		t.Fatalf("kept %d of %d, cut %v", w.b.Len(), len(big), w.cut)
+	}
+}
+
+func TestKitTheRealRunnerRunsEndsAndReportsAMissingProgram(t *testing.T) {
+	r := execRun(Cmd{Name: "sh", Args: []string{"-c", "echo out; echo err >&2; exit 3"}})
+	if r.Status != 3 || strings.TrimSpace(r.Stdout) != "out" || strings.TrimSpace(r.Stderr) != "err" {
+		t.Fatalf("%+v", r)
+	}
+	r = execRun(Cmd{Name: "sh", Args: []string{"-c", "sleep 5 & sleep 5"}, Timeout: 200 * time.Millisecond})
+	if r.Error != "timeout" {
+		t.Fatalf("a slow command: %+v", r)
+	}
+	r = execRun(Cmd{Name: "no-such-program-anywhere"})
+	if r.Error != "not-found" {
+		t.Fatalf("a missing program: %+v", r)
+	}
+	r = execRun(Cmd{Name: "cat", Stdin: "given"})
+	if r.Stdout != "given" {
+		t.Fatalf("stdin: %+v", r)
+	}
+	start := time.Now()
+	r = execRun(Cmd{Name: "sh", Args: []string{"-c", "echo kept; (sleep 3 &) ; exit 0"}, Detached: true})
+	if r.Status != 0 || strings.TrimSpace(r.Stdout) != "kept" || time.Since(start) > 2*time.Second {
+		t.Fatalf("a detached command returns when it exits, not when its child does: %+v after %s", r, time.Since(start))
+	}
+}
+
+func TestKitArgumentsAreReadStrictly(t *testing.T) {
+	args := map[string]any{"s": "x", "n": float64(5), "f": 1.5, "b": true, "l": []any{"a", "b"}}
+	if _, err := text(args, "missing"); err == nil {
+		t.Error("a missing required string")
+	}
+	if n, _ := optWhole(args, "n", 1, 1, 3); n != 3 {
+		t.Errorf("held to most: %d", n)
+	}
+	if _, err := optWhole(args, "n", 1, 6, 9); err == nil {
+		t.Error("below least")
+	}
+	if _, err := optWhole(args, "f", 1, 0, 9); err == nil {
+		t.Error("a fraction")
+	}
+	if l, _ := optList(args, "l"); len(l) != 2 {
+		t.Errorf("list: %v", l)
+	}
+	if b, _ := optFlag(args, "b", false); !b {
+		t.Error("flag")
+	}
+	if err := plainName("name", "--all"); err == nil {
+		t.Error("an option as a name")
+	}
+}

modules/cups/cmd/cups-tools/main.go

@@ -0,0 +1,177 @@
+// The cups module's tools (novox/hq research 027/02, 026/05): the printers, their state, supplies and
+// driver, the queue, and printing, cancelling and choosing the default. A Go bundle the node's runtime
+// launches over stdio (ADR 0188, ADR 0193); it runs as the operator account. An act CUPS keeps for
+// its administrators goes through `sudo -n`.
+package main
+
+import (
+	"fmt"
+	"os"
+
+	stdio "git.novox.be/novox/mesh-sdk/go"
+)
+
+var providedBy = map[string]string{
+	"lpstat":     "the cups package, which this module installs",
+	"lpoptions":  "the cups package, which this module installs",
+	"lp":         "the cups package, which this module installs",
+	"cancel":     "the cups package, which this module installs",
+	"lpadmin":    "the cups package, which this module installs",
+	"lpinfo":     "the cups package, which this module installs",
+	"cupsenable": "the cups package, which this module installs",
+	"cupsaccept": "the cups package, which this module installs",
+	"pacman":     "this is not an Arch machine",
+}
+
+func main() {
+	if err := stdio.Serve("", tools()); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
+
+var printerArg = map[string]any{"type": "string", "description": "the printer's queue name, as cups_printers answers it"}
+
+func tools() []stdio.Tool {
+	return []stdio.Tool{
+		{
+			Name: "cups_printers",
+			Description: "Every printer queue: state, whether it is enabled and accepting jobs, the default, its device " +
+				"address, make and model, whether it prints driverless (IPP Everywhere), the reasons for its state, and " +
+				"supply levels where the printer reports them. (r)",
+			Input: map[string]any{},
+			Run:   func(map[string]any) (any, error) { return Printers() },
+		},
+		{
+			Name: "cups_queue",
+			Description: "The jobs waiting or printing, on every printer or one; or, with completed, the finished ones. " +
+				"Each with its id, printer, owner, size and when it was submitted. (r)",
+			Input: map[string]any{
+				"printer":   printerArg,
+				"completed": map[string]any{"type": "boolean", "description": "the finished jobs instead"},
+				"limit":     map[string]any{"type": "integer", "description": "at most this many, newest first (default 50, at most 500)"},
+			},
+			Run: func(args map[string]any) (any, error) {
+				p, err := optText(args, "printer", "")
+				if err != nil {
+					return nil, err
+				}
+				done, err := optFlag(args, "completed", false)
+				if err != nil {
+					return nil, err
+				}
+				limit, err := optWhole(args, "limit", 50, 1, 500)
+				if err != nil {
+					return nil, err
+				}
+				return Queue(p, done, limit)
+			},
+		},
+		{
+			Name: "cups_cancel",
+			Description: "Cancel one job by its id (\"Brother-12\" or 12), or every job on a printer with all. Another " +
+				"account's job is cancelled through sudo -n. (a)",
+			Input: map[string]any{
+				"job":     map[string]any{"type": "string", "description": "the job id"},
+				"printer": printerArg,
+				"all":     map[string]any{"type": "boolean", "description": "every job on printer"},
+			},
+			Run: func(args map[string]any) (any, error) {
+				job, err := optText(args, "job", "")
+				if err != nil {
+					return nil, err
+				}
+				p, err := optText(args, "printer", "")
+				if err != nil {
+					return nil, err
+				}
+				all, err := optFlag(args, "all", false)
+				if err != nil {
+					return nil, err
+				}
+				return Cancel(job, p, all)
+			},
+		},
+		{
+			Name: "cups_print",
+			Description: "Print a file on this machine, to a printer or the default, with copies and IPP options such as " +
+				"sides=two-sided-long-edge or media=A4. Answers the job id. (a)",
+			Input: map[string]any{
+				"file":    map[string]any{"type": "string", "description": "the file's absolute path on this machine"},
+				"printer": printerArg,
+				"copies":  map[string]any{"type": "integer", "description": "copies (default 1, at most 99)"},
+				"options": map[string]any{"type": "object", "additionalProperties": map[string]any{"type": "string"}, "description": "IPP options, name to value"},
+				"title":   map[string]any{"type": "string", "description": "the job's title (default the file's name)"},
+			},
+			Run: func(args map[string]any) (any, error) {
+				file, err := text(args, "file")
+				if err != nil {
+					return nil, err
+				}
+				p, err := optText(args, "printer", "")
+				if err != nil {
+					return nil, err
+				}
+				copies, err := optWhole(args, "copies", 1, 1, 99)
+				if err != nil {
+					return nil, err
+				}
+				opts, err := optionsOf(args)
+				if err != nil {
+					return nil, err
+				}
+				title, err := optText(args, "title", "")
+				if err != nil {
+					return nil, err
+				}
+				return Print(file, p, copies, opts, title)
+			},
+		},
+		{
+			Name: "cups_default",
+			Description: "The machine's default printer; with printer, make that printer the default (through sudo -n). " +
+				"The default is CUPS's own setting, kept as the operator chose it: the mesh does not declare it. (r/a)",
+			Input: map[string]any{"printer": printerArg},
+			Run: func(args map[string]any) (any, error) {
+				p, err := optText(args, "printer", "")
+				if err != nil {
+					return nil, err
+				}
+				return Default(p)
+			},
+		},
+		{
+			Name:        "cups_resume",
+			Description: "Enable a printer and make it accept jobs again, after CUPS stopped it on an error. Through sudo -n. (a)",
+			Input:       map[string]any{"printer": printerArg},
+			Run: func(args map[string]any) (any, error) {
+				p, err := text(args, "printer")
+				if err != nil {
+					return nil, err
+				}
+				return Resume(p)
+			},
+		},
+		{
+			Name: "cups_drivers",
+			Description: "What each printer prints through (driverless or a driver's PPD), the packages that bring drivers " +
+				"and backends, which of them are from outside the official repositories, and the driver models CUPS " +
+				"offers, filtered by match. (r)",
+			Input: map[string]any{
+				"match": map[string]any{"type": "string", "description": "only models whose description contains this, any case"},
+				"limit": map[string]any{"type": "integer", "description": "at most this many models (default 50, at most 1000)"},
+			},
+			Run: func(args map[string]any) (any, error) {
+				match, err := optText(args, "match", "")
+				if err != nil {
+					return nil, err
+				}
+				limit, err := optWhole(args, "limit", 50, 0, 1000)
+				if err != nil {
+					return nil, err
+				}
+				return Drivers(match, limit)
+			},
+		},
+	}
+}

modules/cups/cmd/cups-tools/manifest_kit_test.go

@@ -0,0 +1,107 @@
+package main
+
+// manifest_kit_test.go is the same file in each workstation module: it reads the module's
+// definition so the module's own tests can hold it to what it says.
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"testing"
+)
+
+type manifest struct {
+	Module       string           `json:"module"`
+	Capabilities []string         `json:"capabilities"`
+	Claims       []any            `json:"claims"`
+	Seats        []any            `json:"seats"`
+	Tools        []string         `json:"tools"`
+	Resources    []map[string]any `json:"resources"`
+	Build        struct {
+		Artifacts []map[string]any `json:"artifacts"`
+	} `json:"build"`
+}
+
+func readManifest(t *testing.T) manifest {
+	t.Helper()
+	raw, err := os.ReadFile(filepath.Join("..", "..", "module.json"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	var m manifest
+	if err := json.Unmarshal(raw, &m); err != nil {
+		t.Fatalf("module.json: %v", err)
+	}
+	return m
+}
+
+func (m manifest) resource(id string) map[string]any {
+	for _, r := range m.Resources {
+		if r["id"] == id {
+			return r
+		}
+	}
+	return nil
+}
+
+// packages are the packages the module installs, sorted.
+func (m manifest) packages() []string {
+	out := []string{}
+	for _, r := range m.Resources {
+		if r["type"] == "package" && r["absent"] != true {
+			out = append(out, r["package"].(string))
+		}
+	}
+	sort.Strings(out)
+	return out
+}
+
+// services are the units the module declares, by unit name.
+func (m manifest) services() map[string]map[string]any {
+	out := map[string]map[string]any{}
+	for _, r := range m.Resources {
+		if r["type"] == "service" {
+			out[r["unit"].(string)] = r
+		}
+	}
+	return out
+}
+
+// holdsTheBundle holds the manifest to the Go bundle this directory builds: every tool registered
+// is listed and nothing else, each named <prefix>_…, and the artifact builds this command.
+func holdsTheBundle(t *testing.T, m manifest, prefix string) {
+	t.Helper()
+	registered := []string{}
+	for _, tool := range tools() {
+		registered = append(registered, tool.Name)
+		if !strings.HasPrefix(tool.Name, prefix+"_") {
+			t.Errorf("tool %s is not named %s_…", tool.Name, prefix)
+		}
+		if tool.Description == "" || tool.Run == nil || tool.Input == nil {
+			t.Errorf("tool %s is not described, runnable and given an input schema", tool.Name)
+		}
+	}
+	if strings.Join(registered, ",") != strings.Join(m.Tools, ",") {
+		t.Errorf("registered %v, listed %v", registered, m.Tools)
+	}
+	if len(m.Build.Artifacts) != 1 {
+		t.Fatalf("one artifact, got %d", len(m.Build.Artifacts))
+	}
+	cwd, _ := os.Getwd()
+	binary := filepath.Base(cwd)
+	a := m.Build.Artifacts[0]
+	want := map[string]any{"kind": "bundle", "language": "go", "system": "arch", "from": "cmd/" + binary, "binary": binary}
+	for k, v := range want {
+		if a[k] != v {
+			t.Errorf("artifact %s = %v, want %v", k, a[k], v)
+		}
+	}
+	if loads, _ := a["loads"].([]any); len(loads) != 1 || loads[0] != binary {
+		t.Errorf("artifact loads %v, want [%s]", a["loads"], binary)
+	}
+	if m.Claims != nil || m.Seats != nil {
+		t.Errorf("claims %v, seats %v: this module holds no seat", m.Claims, m.Seats)
+	}
+}

modules/cups/go.mod

@@ -0,0 +1,5 @@
+module cups
+
+go 1.22
+
+require git.novox.be/novox/mesh-sdk/go v0.1.6

modules/cups/go.sum

@@ -0,0 +1,2 @@
+git.novox.be/novox/mesh-sdk/go v0.1.6 h1:9qzdYONYbJdWcu6sxQcq9v1LI0JxcfkiKYkMUzJSkVQ=
+git.novox.be/novox/mesh-sdk/go v0.1.6/go.mod h1:GFuZUElBZ9A++mxgIKo97aXXo+kV0uJ/UkbhQPPIbrY=

modules/cups/module.json

@@ -0,0 +1,58 @@
+{
+  "module": "cups",
+  "version": "1",
+  "capabilities": [
+    "package-manager",
+    "service-manager"
+  ],
+  "tools": [
+    "cups_printers",
+    "cups_queue",
+    "cups_cancel",
+    "cups_print",
+    "cups_default",
+    "cups_resume",
+    "cups_drivers"
+  ],
+  "resources": [
+    {
+      "id": "package",
+      "type": "package",
+      "package": "cups"
+    },
+    {
+      "id": "driverless",
+      "type": "package",
+      "package": "cups-filters"
+    },
+    {
+      "id": "socket",
+      "type": "service",
+      "unit": "cups.socket",
+      "state": "running",
+      "boot": "enabled"
+    },
+    {
+      "id": "scheduler",
+      "type": "service",
+      "unit": "cups.service",
+      "state": "running",
+      "boot": "enabled"
+    }
+  ],
+  "build": {
+    "artifacts": [
+      {
+        "name": "tools",
+        "kind": "bundle",
+        "language": "go",
+        "system": "arch",
+        "from": "cmd/cups-tools",
+        "binary": "cups-tools",
+        "loads": [
+          "cups-tools"
+        ]
+      }
+    ]
+  }
+}

modules/dmenu/README.md

@@ -0,0 +1,56 @@
+# dmenu
+
+The suckless menu, as a module (novox/hq research 026/04: "`dmenu` is a module of its own (official
+repositories), able to hold the same seat on a machine that wants it"; to-be 42 phase 2 step 7).
+
+## Owns
+
+| what | where |
+|---|---|
+| `dmenu`, `dmenu_run`, `dmenu_path`, `stest` | package `dmenu` (official repositories) |
+
+## Improves: two broken calls work by existing
+
+Research 026/04 measured "plain `dmenu` in two places" in the operator's configuration, with dmenu
+installed on neither workstation, so both failed. Measured again on 2026-10-04, the two are one line on
+each workstation, in the notifier's configuration:
+
+- `~/.config/dunst/dunstrc`: `dmenu = /usr/bin/dmenu -p dunst:`
+
+It is the menu dunst opens to pick a notification's action or link. Every other menu in the
+operator's scripts calls `rofi -dmenu`. Once this module installs the package, `/usr/bin/dmenu` exists
+and that menu opens. The `dunst` module may later point the line at the launcher seat's command
+instead (below). The line is that module's to own, so this module does not touch it.
+
+## The seat it would hold: not claimed yet
+
+Research 026/04 gives `node-launcher` to `rofi`, with a dmenu-compatible command as part of its
+protocol, and lets `dmenu` hold the same seat on a machine that wants it. **The seat is not in the
+controller's seat table yet**, and a claim on an unknown seat is refused. So this module claims
+nothing. Its tool `dmenu_menu` is shaped like the seat's `menu` verb (research 026/05): show a list,
+answer the chosen line. When the seat is recorded, the claim is one line here, serving `menu`.
+
+## Tools
+
+All answer JSON. `(r)` reads; `(d)` acts in the operator's session.
+
+| tool | what |
+|---|---|
+| `dmenu_menu` (d) | show up to 1000 choices, with a prompt, as one line or a vertical list, case-insensitive by default. Answers the chosen line and its index; a typed line that is not a choice (`typed`); `cancelled` when dismissed; `timed_out` when not answered in time (default 20 s, at most 25, below the runtime's 30 s call limit) |
+| `dmenu_session` (r) | the session the menu would appear in and how it was found, or why there is none; dmenu's version |
+
+**Reaching the session** works as the `xclip` module's README describes: the runtime runs as the
+account with no session words, and `session.go` finds the account's display and cookie from its own
+processes. With no session, the tool says so and shows nothing. A keyboard held by another program
+(a locked screen, an open menu) is answered as such.
+
+The menu draws in fontconfig's `monospace` at dmenu's default size, which the `fonts` module makes
+JetBrains Mono Nerd Font.
+
+## What changes when it is assigned
+
+On both workstations, the `dmenu` package is installed, which neither has today. Nothing else.
+
+## Leaves as found
+
+The notifier's configuration, and every `rofi -dmenu` call in the operator's scripts.

modules/dmenu/cmd/dmenu-tools/dmenu.go

@@ -0,0 +1,112 @@
+package main
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// MostWait is the longest a menu stays open: below the runtime's 30 s call limit, so an unanswered
+// menu is answered as such rather than as a call the runtime gave up on.
+const MostWait = 25
+
+// MostChoices bounds the list.
+const MostChoices = 1000
+
+// Ask is one menu.
+type Ask struct {
+	Choices         []string
+	Prompt          string
+	Lines           int
+	CaseInsensitive bool
+	Timeout         int
+}
+
+// MenuAnswer is what dmenu_menu answers.
+type MenuAnswer struct {
+	Chosen    string  `json:"chosen,omitempty"`
+	Index     int     `json:"index"`
+	Typed     bool    `json:"typed"`
+	Cancelled bool    `json:"cancelled"`
+	TimedOut  bool    `json:"timed_out"`
+	Session   Session `json:"session"`
+}
+
+// Menu shows the choices and answers the one taken. dmenu prints the selected (or typed) line and
+// exits 0; it exits 1 with nothing printed when dismissed.
+func Menu(a Ask) (MenuAnswer, error) {
+	if len(a.Choices) == 0 {
+		return MenuAnswer{}, fmt.Errorf("choices is required: at least one line")
+	}
+	if len(a.Choices) > MostChoices {
+		return MenuAnswer{}, fmt.Errorf("%d choices; at most %d are shown", len(a.Choices), MostChoices)
+	}
+	for _, c := range a.Choices {
+		if strings.ContainsAny(c, "\n\r") {
+			return MenuAnswer{}, fmt.Errorf("a choice holds a line break: %q", c)
+		}
+	}
+	if strings.ContainsAny(a.Prompt, "\n\r") {
+		return MenuAnswer{}, fmt.Errorf("the prompt holds a line break")
+	}
+	s, err := findSession()
+	if err != nil {
+		return MenuAnswer{}, err
+	}
+	args := []string{}
+	if a.CaseInsensitive {
+		args = append(args, "-i")
+	}
+	if a.Lines > 0 {
+		args = append(args, "-l", strconv.Itoa(a.Lines))
+	}
+	if a.Prompt != "" {
+		args = append(args, "-p", a.Prompt)
+	}
+	c := Cmd{Name: "dmenu", Args: args, Stdin: strings.Join(a.Choices, "\n") + "\n", Env: s.Env(), Timeout: time.Duration(a.Timeout) * time.Second}
+	r := run(c)
+	out := MenuAnswer{Index: -1, Session: s}
+	switch {
+	case r.Error == "timeout":
+		out.TimedOut = true
+		return out, nil
+	case r.Error != "":
+		return MenuAnswer{}, failure(c, r)
+	case strings.Contains(r.Stderr, "cannot open display"):
+		return MenuAnswer{}, fmt.Errorf("the X session at %s (found by %s) refused the connection", s.Display, s.FoundBy)
+	case strings.Contains(r.Stderr, "cannot grab keyboard"):
+		return MenuAnswer{}, fmt.Errorf("dmenu could not take the keyboard: another program holds it (a locked screen, an open menu)")
+	case r.Status == 1 && strings.TrimSpace(r.Stdout) == "":
+		out.Cancelled = true
+		return out, nil
+	case r.Status != 0:
+		return MenuAnswer{}, failure(c, r)
+	}
+	out.Chosen = strings.TrimRight(r.Stdout, "\r\n")
+	for i, ch := range a.Choices {
+		if ch == out.Chosen {
+			out.Index = i
+			break
+		}
+	}
+	out.Typed = out.Index < 0
+	return out, nil
+}
+
+// SessionCheck answers the session the menu would appear in, and dmenu's version.
+func SessionCheck() (map[string]any, error) {
+	out := map[string]any{}
+	if r := run(Cmd{Name: "dmenu", Args: []string{"-v"}}); r.Error == "" {
+		out["dmenu"] = strings.TrimSpace(r.Stdout + r.Stderr)
+	} else {
+		out["dmenu"] = failure(Cmd{Name: "dmenu"}, r).Error()
+	}
+	s, err := findSession()
+	if err != nil {
+		out["found"], out["why"] = false, err.Error()
+		return out, nil
+	}
+	out["found"], out["session"] = true, s
+	return out, nil
+}

modules/dmenu/cmd/dmenu-tools/dmenu_test.go

@@ -0,0 +1,108 @@
+package main
+
+import (
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestTheManifestIsThePackageAndClaimsNoSeatYet(t *testing.T) {
+	m := readManifest(t)
+	// holdsTheBundle also holds it to no claim: node-launcher is not in the controller's seat table
+	// yet (README).
+	holdsTheBundle(t, m, "dmenu")
+	if got := strings.Join(m.packages(), ","); got != "dmenu" || len(m.Resources) != 1 {
+		t.Errorf("packages %s, resources %v", got, m.Resources)
+	}
+}
+
+func aSession(t *testing.T) {
+	t.Helper()
+	_, sockets := aMachine(t, map[string]string{"DISPLAY": ":1", "XAUTHORITY": "/home/op/.Xauthority"})
+	aSocket(t, sockets, "X1")
+}
+
+func TestMenuShowsTheChoicesInTheSessionAndAnswersTheOneTaken(t *testing.T) {
+	aSession(t)
+	f := using(t, func(string, Cmd) Result { return ok("Lock\n") })
+	got, err := Menu(Ask{Choices: []string{"Shutdown", "Lock"}, Prompt: "power:", Lines: 5, CaseInsensitive: true, Timeout: 20})
+	if err != nil || got.Chosen != "Lock" || got.Index != 1 || got.Typed || got.Cancelled || got.TimedOut {
+		t.Fatalf("%+v %v", got, err)
+	}
+	c := f.asked[0]
+	if f.lines()[0] != "dmenu -i -l 5 -p power:" || c.Stdin != "Shutdown\nLock\n" || c.Timeout != 20*time.Second {
+		t.Errorf("%v %+v", f.lines(), c)
+	}
+	if strings.Join(c.Env, " ") != "DISPLAY=:1 XAUTHORITY=/home/op/.Xauthority" {
+		t.Errorf("env %v", c.Env)
+	}
+}
+
+func TestMenuTellsTypedDismissedAndUnansweredApart(t *testing.T) {
+	aSession(t)
+	answer := ok("something else\n")
+	using(t, func(string, Cmd) Result { return answer })
+	got, err := Menu(Ask{Choices: []string{"a"}, Timeout: 5})
+	if err != nil || !got.Typed || got.Index != -1 || got.Chosen != "something else" {
+		t.Errorf("typed: %+v %v", got, err)
+	}
+	answer = Result{Status: 1}
+	got, err = Menu(Ask{Choices: []string{"a"}, Timeout: 5})
+	if err != nil || !got.Cancelled || got.Chosen != "" {
+		t.Errorf("dismissed: %+v %v", got, err)
+	}
+	answer = Result{Status: 124, Error: "timeout"}
+	got, err = Menu(Ask{Choices: []string{"a"}, Timeout: 5})
+	if err != nil || !got.TimedOut {
+		t.Errorf("unanswered: %+v %v", got, err)
+	}
+	answer = Result{Status: 1, Stderr: "cannot grab keyboard\n"}
+	if _, err := Menu(Ask{Choices: []string{"a"}, Timeout: 5}); err == nil || !strings.Contains(err.Error(), "keyboard") {
+		t.Errorf("a held keyboard: %v", err)
+	}
+	answer = Result{Status: 1, Stderr: "cannot open display\n"}
+	if _, err := Menu(Ask{Choices: []string{"a"}, Timeout: 5}); err == nil || !strings.Contains(err.Error(), "refused") {
+		t.Errorf("a refusing display: %v", err)
+	}
+}
+
+func TestMenuRefusesWhatCannotBeShownAndRunsNothingWithoutASession(t *testing.T) {
+	aSession(t)
+	f := using(t, func(string, Cmd) Result { return ok("") })
+	for _, bad := range []Ask{{}, {Choices: []string{"a\nb"}}, {Choices: []string{"a"}, Prompt: "x\ny"}, {Choices: make([]string, MostChoices+1)}} {
+		if _, err := Menu(bad); err == nil {
+			t.Errorf("%+v accepted", bad)
+		}
+	}
+	aMachine(t, map[string]string{})
+	if _, err := Menu(Ask{Choices: []string{"a"}, Timeout: 5}); err == nil || !strings.Contains(err.Error(), "no graphical session") {
+		t.Errorf("%v", err)
+	}
+	if len(f.asked) != 0 {
+		t.Errorf("ran %v", f.lines())
+	}
+}
+
+func TestTheWaitIsBelowTheRuntimesCallLimit(t *testing.T) {
+	if MostWait >= 30 {
+		t.Fatalf("a menu may stay open %d s; the runtime gives a call 30", MostWait)
+	}
+	n, _ := optWhole(map[string]any{"timeout_seconds": float64(600)}, "timeout_seconds", 20, 1, MostWait)
+	if n != MostWait {
+		t.Errorf("%d", n)
+	}
+}
+
+func TestSessionCheckSaysTheVersionAndTheSession(t *testing.T) {
+	aSession(t)
+	using(t, func(string, Cmd) Result { return ok("dmenu-5.4\n") })
+	got, err := SessionCheck()
+	if err != nil || got["dmenu"] != "dmenu-5.4" || got["found"] != true {
+		t.Fatalf("%v %v", got, err)
+	}
+	using(t, func(string, Cmd) Result { return Result{Status: 127, Error: "not-found"} })
+	got, _ = SessionCheck()
+	if !strings.Contains(got["dmenu"].(string), "not installed") {
+		t.Errorf("%v", got)
+	}
+}

modules/dmenu/cmd/dmenu-tools/kit.go

@@ -0,0 +1,352 @@
+package main
+
+// kit.go is the same file in each of the workstations' tool bundles (fonts, docker-compose, snapd,
+// flatpak, cups, bluetooth, xclip, dmenu): how a tool runs a command, escalates, bounds what it
+// keeps, and names a failure. A module is built from its own directory, so the file is copied rather
+// than shared; a change to one copy is made to all eight.
+//
+// The rules it holds (novox/hq research 026/05, to-be 38 WP4):
+//   - the node's tool runtime runs as the operator account, not root (ADR 0175 §4); a command that
+//     needs root goes through `sudo -n`, never a prompt, and a refusal is named as such;
+//   - one command gets 20 s, below the runtime's 30 s call limit, and is ended with everything it
+//     started when it takes longer;
+//   - each stream is kept to 256 KiB, and the answer says when it was cut;
+//   - a failure is an error with what went wrong in it, never an empty answer.
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"strings"
+	"syscall"
+	"time"
+)
+
+// Bounds every command is held to.
+const (
+	CallTimeout = 20 * time.Second
+	MostOutput  = 256 << 10
+)
+
+// Cmd is one command a tool runs.
+type Cmd struct {
+	Name string
+	Args []string
+	// Stdin is written to the command's standard input when not empty.
+	Stdin string
+	// Env is added to this process's own environment.
+	Env []string
+	// Root says the command needs root: it is run through `sudo -n` when this process is not root.
+	Root bool
+	// Timeout replaces CallTimeout; only a background job (jobs.go) asks for longer.
+	Timeout time.Duration
+	// Detached is for a program that forks a child which outlives it, as xclip does to keep the
+	// selection: its streams go to files, because a pipe the child inherits would hold the call open
+	// until the child exits.
+	Detached bool
+}
+
+// Result is what a command did.
+type Result struct {
+	Stdout string `json:"stdout"`
+	Stderr string `json:"stderr"`
+	Status int    `json:"status"`
+	// Error is why it did not run to an answer: "not-found" when the program is not there,
+	// "timeout" when it was ended for taking too long, else the spawn error.
+	Error     string `json:"error,omitempty"`
+	Truncated bool   `json:"truncated,omitempty"`
+}
+
+// Runner runs a command. Tests replace it; nothing else does.
+type Runner func(Cmd) Result
+
+var (
+	run  Runner = execRun
+	euid        = os.Geteuid
+)
+
+// argv is the command as it is run: through sudo without a prompt when it needs root and this
+// process is not root.
+func argv(c Cmd) (string, []string) {
+	if c.Root && euid() != 0 {
+		return "sudo", append([]string{"-n", c.Name}, c.Args...)
+	}
+	return c.Name, c.Args
+}
+
+// bounded keeps the first MostOutput bytes written to it and notes that more came.
+type bounded struct {
+	b   bytes.Buffer
+	cut bool
+}
+
+func (w *bounded) Write(p []byte) (int, error) {
+	room := MostOutput - w.b.Len()
+	if room <= 0 {
+		w.cut = w.cut || len(p) > 0
+		return len(p), nil
+	}
+	if len(p) > room {
+		w.b.Write(p[:room])
+		w.cut = true
+		return len(p), nil
+	}
+	return w.b.Write(p)
+}
+
+func execRun(c Cmd) Result {
+	timeout := c.Timeout
+	if timeout <= 0 {
+		timeout = CallTimeout
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), timeout)
+	defer cancel()
+	name, args := argv(c)
+	cmd := exec.CommandContext(ctx, name, args...)
+	cmd.Env = append(append(os.Environ(), "LC_ALL=C"), c.Env...)
+	if !c.Detached {
+		// Its own process group, so that ending it on a timeout ends what it started too.
+		cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+		cmd.Cancel = func() error {
+			if cmd.Process != nil {
+				_ = syscall.Kill(-cmd.Process.Pid, syscall.SIGKILL)
+			}
+			return nil
+		}
+	}
+	cmd.WaitDelay = 2 * time.Second
+	if c.Stdin != "" {
+		cmd.Stdin = strings.NewReader(c.Stdin)
+	}
+	var out, errs bounded
+	var outFile, errFile *os.File
+	if c.Detached {
+		var err error
+		if outFile, err = os.CreateTemp("", "mesh-tool-out-*"); err != nil {
+			return Result{Status: 127, Error: err.Error()}
+		}
+		defer os.Remove(outFile.Name())
+		defer outFile.Close()
+		if errFile, err = os.CreateTemp("", "mesh-tool-err-*"); err != nil {
+			return Result{Status: 127, Error: err.Error()}
+		}
+		defer os.Remove(errFile.Name())
+		defer errFile.Close()
+		cmd.Stdout, cmd.Stderr = outFile, errFile
+	} else {
+		cmd.Stdout, cmd.Stderr = &out, &errs
+	}
+	err := cmd.Run()
+	if c.Detached {
+		for _, f := range []struct {
+			file *os.File
+			into *bounded
+		}{{outFile, &out}, {errFile, &errs}} {
+			if _, e := f.file.Seek(0, io.SeekStart); e == nil {
+				_, _ = io.Copy(f.into, f.file)
+			}
+		}
+	}
+	r := Result{Stdout: out.b.String(), Stderr: errs.b.String(), Truncated: out.cut || errs.cut}
+	var exit *exec.ExitError
+	switch {
+	case err == nil:
+	case ctx.Err() == context.DeadlineExceeded:
+		r.Status, r.Error = 124, "timeout"
+	case errors.Is(err, exec.ErrNotFound) || errors.Is(err, os.ErrNotExist):
+		r.Status, r.Error = 127, "not-found"
+	case errors.As(err, &exit):
+		r.Status = exit.ExitCode()
+	default:
+		r.Status, r.Error = 127, err.Error()
+	}
+	return r
+}
+
+// call runs a command and answers its result, or an error naming what went wrong.
+func call(c Cmd) (Result, error) {
+	r := run(c)
+	if r.Status == 0 && r.Error == "" {
+		return r, nil
+	}
+	return r, failure(c, r)
+}
+
+// failure names how a command failed: not installed, refused escalation, too slow, or its exit
+// status with the end of what it said.
+func failure(c Cmd, r Result) error {
+	program, _ := argv(c)
+	switch {
+	case r.Error == "not-found" && program == "sudo":
+		return fmt.Errorf("%s needs root, and sudo is not installed here for the runtime's account to escalate with", c.Name)
+	case r.Error == "not-found":
+		if hint, ok := providedBy[c.Name]; ok {
+			return fmt.Errorf("%s is not installed on this machine (%s)", c.Name, hint)
+		}
+		return fmt.Errorf("%s is not installed on this machine", c.Name)
+	case r.Error == "timeout":
+		limit := c.Timeout
+		if limit <= 0 {
+			limit = CallTimeout
+		}
+		return fmt.Errorf("%s gave no answer within %s and was ended", c.Name, limit)
+	case r.Error != "":
+		return fmt.Errorf("%s did not run: %s", c.Name, r.Error)
+	case program == "sudo" && strings.Contains(r.Stderr, "command not found"):
+		if hint, ok := providedBy[c.Name]; ok {
+			return fmt.Errorf("%s is not installed on this machine (%s)", c.Name, hint)
+		}
+		return fmt.Errorf("%s is not installed on this machine", c.Name)
+	case program == "sudo" && strings.HasPrefix(strings.TrimSpace(r.Stderr), "sudo:"):
+		return fmt.Errorf("%s needs root, and sudo -n refused the runtime's account: %s (the escalation is the sudo module's to declare)",
+			c.Name, firstLine(r.Stderr))
+	}
+	said := tail(strings.TrimSpace(r.Stderr), 2000)
+	if said == "" {
+		said = tail(strings.TrimSpace(r.Stdout), 2000)
+	}
+	if said == "" {
+		said = "and said nothing"
+	}
+	return fmt.Errorf("%s %s exited %d: %s", c.Name, strings.Join(c.Args, " "), r.Status, said)
+}
+
+func firstLine(s string) string {
+	s = strings.TrimSpace(s)
+	if i := strings.IndexByte(s, '\n'); i >= 0 {
+		return s[:i]
+	}
+	return s
+}
+
+func tail(s string, n int) string {
+	if len(s) <= n {
+		return s
+	}
+	return "…" + s[len(s)-n:]
+}
+
+// lines are a command's output lines, blank ones dropped.
+func lines(s string) []string {
+	out := []string{}
+	for _, l := range strings.Split(s, "\n") {
+		if strings.TrimSpace(l) != "" {
+			out = append(out, strings.TrimRight(l, "\r"))
+		}
+	}
+	return out
+}
+
+// Arguments, read the way a tool's JSON arguments arrive.
+
+func text(args map[string]any, key string) (string, error) {
+	v, ok := args[key]
+	if !ok || v == nil {
+		return "", fmt.Errorf("%s is required", key)
+	}
+	s, ok := v.(string)
+	if !ok {
+		return "", fmt.Errorf("%s must be a string", key)
+	}
+	if strings.TrimSpace(s) == "" {
+		return "", fmt.Errorf("%s must not be empty", key)
+	}
+	return s, nil
+}
+
+func optText(args map[string]any, key, def string) (string, error) {
+	v, ok := args[key]
+	if !ok || v == nil {
+		return def, nil
+	}
+	s, ok := v.(string)
+	if !ok {
+		return "", fmt.Errorf("%s must be a string", key)
+	}
+	if strings.TrimSpace(s) == "" {
+		return def, nil
+	}
+	return s, nil
+}
+
+// optWhole reads a whole number, defaulted, refused below least and held to most.
+func optWhole(args map[string]any, key string, def, least, most int) (int, error) {
+	v, ok := args[key]
+	if !ok || v == nil {
+		return def, nil
+	}
+	f, ok := v.(float64)
+	if !ok {
+		if i, isInt := v.(int); isInt {
+			f = float64(i)
+		} else {
+			return 0, fmt.Errorf("%s must be a number", key)
+		}
+	}
+	if f != float64(int(f)) {
+		return 0, fmt.Errorf("%s must be a whole number", key)
+	}
+	n := int(f)
+	if n < least {
+		return 0, fmt.Errorf("%s must be at least %d", key, least)
+	}
+	if n > most {
+		n = most
+	}
+	return n, nil
+}
+
+func optFlag(args map[string]any, key string, def bool) (bool, error) {
+	v, ok := args[key]
+	if !ok || v == nil {
+		return def, nil
+	}
+	b, ok := v.(bool)
+	if !ok {
+		return false, fmt.Errorf("%s must be true or false", key)
+	}
+	return b, nil
+}
+
+func optList(args map[string]any, key string) ([]string, error) {
+	v, ok := args[key]
+	if !ok || v == nil {
+		return nil, nil
+	}
+	items, ok := v.([]any)
+	if !ok {
+		return nil, fmt.Errorf("%s must be a list of strings", key)
+	}
+	out := make([]string, 0, len(items))
+	for _, it := range items {
+		s, ok := it.(string)
+		if !ok || strings.TrimSpace(s) == "" {
+			return nil, fmt.Errorf("%s must be a list of non-empty strings", key)
+		}
+		out = append(out, s)
+	}
+	return out, nil
+}
+
+// oneOf refuses a value outside a closed set.
+func oneOf(key, value string, allowed ...string) error {
+	for _, a := range allowed {
+		if value == a {
+			return nil
+		}
+	}
+	return fmt.Errorf("%s must be one of %s, not %q", key, strings.Join(allowed, ", "), value)
+}
+
+// plainName refuses a name that could be read as an option or carries a path or a space: package,
+// snap, application and printer names never do.
+func plainName(key, value string) error {
+	if strings.HasPrefix(value, "-") || strings.ContainsAny(value, " \t\n/\\") {
+		return fmt.Errorf("%s %q is not a plain name", key, value)
+	}
+	return nil
+}

modules/dmenu/cmd/dmenu-tools/kit_test.go

@@ -0,0 +1,147 @@
+package main
+
+// Tests of kit.go, the same in each workstation module.
+
+import (
+	"strings"
+	"testing"
+	"time"
+)
+
+// fake records the commands asked and answers each from a function of the command line.
+type fake struct {
+	asked  []Cmd
+	answer func(line string, c Cmd) Result
+}
+
+func (f *fake) runner() Runner {
+	return func(c Cmd) Result {
+		f.asked = append(f.asked, c)
+		name, args := argv(c)
+		line := strings.TrimSpace(name + " " + strings.Join(args, " "))
+		if f.answer == nil {
+			return Result{}
+		}
+		return f.answer(line, c)
+	}
+}
+
+func (f *fake) lines() []string {
+	out := []string{}
+	for _, c := range f.asked {
+		name, args := argv(c)
+		out = append(out, strings.TrimSpace(name+" "+strings.Join(args, " ")))
+	}
+	return out
+}
+
+// using installs a fake runner and a non-root uid for one test.
+func using(t *testing.T, answer func(line string, c Cmd) Result) *fake {
+	t.Helper()
+	f := &fake{answer: answer}
+	wasRun, wasUID := run, euid
+	run, euid = f.runner(), func() int { return 1000 }
+	t.Cleanup(func() { run, euid = wasRun, wasUID })
+	return f
+}
+
+func ok(stdout string) Result { return Result{Stdout: stdout} }
+
+func TestKitAnActThatNeedsRootGoesThroughSudoWithoutAPromptUnlessAlreadyRoot(t *testing.T) {
+	was := euid
+	defer func() { euid = was }()
+	euid = func() int { return 1000 }
+	if name, args := argv(Cmd{Name: "x", Args: []string{"a"}, Root: true}); name != "sudo" || strings.Join(args, " ") != "-n x a" {
+		t.Fatalf("not root: %s %v", name, args)
+	}
+	if name, _ := argv(Cmd{Name: "x"}); name != "x" {
+		t.Fatalf("a read is run as the account: %s", name)
+	}
+	euid = func() int { return 0 }
+	if name, _ := argv(Cmd{Name: "x", Root: true}); name != "x" {
+		t.Fatalf("as root no sudo: %s", name)
+	}
+}
+
+func TestKitAFailureIsNamedByHowItFailed(t *testing.T) {
+	was := euid
+	defer func() { euid = was }()
+	euid = func() int { return 1000 }
+	cases := []struct {
+		c    Cmd
+		r    Result
+		want string
+	}{
+		{Cmd{Name: "nothere"}, Result{Status: 127, Error: "not-found"}, "not installed"},
+		{Cmd{Name: "x", Root: true}, Result{Status: 127, Error: "not-found"}, "sudo is not installed"},
+		{Cmd{Name: "x", Root: true}, Result{Status: 1, Stderr: "sudo: a password is required\n"}, "sudo -n refused"},
+		{Cmd{Name: "x", Root: true}, Result{Status: 1, Stderr: "sudo: x: command not found\n"}, "x is not installed"},
+		{Cmd{Name: "x"}, Result{Status: 124, Error: "timeout"}, "within 20s"},
+		{Cmd{Name: "x", Args: []string{"y"}}, Result{Status: 3, Stderr: "boom\n"}, "x y exited 3: boom"},
+		{Cmd{Name: "x"}, Result{Status: 3}, "said nothing"},
+	}
+	for _, k := range cases {
+		err := failure(k.c, k.r)
+		if err == nil || !strings.Contains(err.Error(), k.want) {
+			t.Errorf("%+v: %v, want %q", k.r, err, k.want)
+		}
+	}
+}
+
+func TestKitOutputIsBoundedAndSaysSo(t *testing.T) {
+	var w bounded
+	big := strings.Repeat("a", MostOutput+10)
+	n, _ := w.Write([]byte(big))
+	if n != len(big) || w.b.Len() != MostOutput || !w.cut {
+		t.Fatalf("kept %d of %d, cut %v", w.b.Len(), len(big), w.cut)
+	}
+}
+
+func TestKitTheRealRunnerRunsEndsAndReportsAMissingProgram(t *testing.T) {
+	r := execRun(Cmd{Name: "sh", Args: []string{"-c", "echo out; echo err >&2; exit 3"}})
+	if r.Status != 3 || strings.TrimSpace(r.Stdout) != "out" || strings.TrimSpace(r.Stderr) != "err" {
+		t.Fatalf("%+v", r)
+	}
+	r = execRun(Cmd{Name: "sh", Args: []string{"-c", "sleep 5 & sleep 5"}, Timeout: 200 * time.Millisecond})
+	if r.Error != "timeout" {
+		t.Fatalf("a slow command: %+v", r)
+	}
+	r = execRun(Cmd{Name: "no-such-program-anywhere"})
+	if r.Error != "not-found" {
+		t.Fatalf("a missing program: %+v", r)
+	}
+	r = execRun(Cmd{Name: "cat", Stdin: "given"})
+	if r.Stdout != "given" {
+		t.Fatalf("stdin: %+v", r)
+	}
+	start := time.Now()
+	r = execRun(Cmd{Name: "sh", Args: []string{"-c", "echo kept; (sleep 3 &) ; exit 0"}, Detached: true})
+	if r.Status != 0 || strings.TrimSpace(r.Stdout) != "kept" || time.Since(start) > 2*time.Second {
+		t.Fatalf("a detached command returns when it exits, not when its child does: %+v after %s", r, time.Since(start))
+	}
+}
+
+func TestKitArgumentsAreReadStrictly(t *testing.T) {
+	args := map[string]any{"s": "x", "n": float64(5), "f": 1.5, "b": true, "l": []any{"a", "b"}}
+	if _, err := text(args, "missing"); err == nil {
+		t.Error("a missing required string")
+	}
+	if n, _ := optWhole(args, "n", 1, 1, 3); n != 3 {
+		t.Errorf("held to most: %d", n)
+	}
+	if _, err := optWhole(args, "n", 1, 6, 9); err == nil {
+		t.Error("below least")
+	}
+	if _, err := optWhole(args, "f", 1, 0, 9); err == nil {
+		t.Error("a fraction")
+	}
+	if l, _ := optList(args, "l"); len(l) != 2 {
+		t.Errorf("list: %v", l)
+	}
+	if b, _ := optFlag(args, "b", false); !b {
+		t.Error("flag")
+	}
+	if err := plainName("name", "--all"); err == nil {
+		t.Error("an option as a name")
+	}
+}

modules/dmenu/cmd/dmenu-tools/main.go

@@ -0,0 +1,70 @@
+// The dmenu module's tool (novox/hq research 026/04, 026/05): show the operator a menu of choices in
+// the graphical session and answer the one chosen — the dmenu-compatible command as a tool. A Go
+// bundle the node's runtime launches over stdio (ADR 0188, ADR 0193). It runs as the operator account
+// and reaches the account's X session as session.go finds it; with no session, it says so.
+package main
+
+import (
+	"fmt"
+	"os"
+
+	stdio "git.novox.be/novox/mesh-sdk/go"
+)
+
+var providedBy = map[string]string{
+	"dmenu": "the dmenu package, which this module installs",
+}
+
+func main() {
+	if err := stdio.Serve("", tools()); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
+
+func tools() []stdio.Tool {
+	return []stdio.Tool{
+		{
+			Name: "dmenu_menu",
+			Description: "Show the operator a menu of choices on their screen and answer the line chosen, its index, or " +
+				"that the menu was dismissed or not answered in time (default 20 s, at most 25). The operator may also " +
+				"type a line that is not a choice. Needs the operator's graphical session. (d)",
+			Input: map[string]any{
+				"choices":          map[string]any{"type": "array", "items": map[string]any{"type": "string"}, "description": "the lines to choose from, at most 1000, none with a line break"},
+				"prompt":           map[string]any{"type": "string", "description": "a prompt shown left of the input"},
+				"lines":            map[string]any{"type": "integer", "description": "show the choices as a vertical list of this many lines (default 0: one horizontal line; at most 40)"},
+				"case_insensitive": map[string]any{"type": "boolean", "description": "match what is typed regardless of case (default true)"},
+				"timeout_seconds":  map[string]any{"type": "integer", "description": "close the menu unanswered after this long (default 20, at most 25)"},
+			},
+			Run: func(args map[string]any) (any, error) {
+				choices, err := optList(args, "choices")
+				if err != nil {
+					return nil, err
+				}
+				prompt, err := optText(args, "prompt", "")
+				if err != nil {
+					return nil, err
+				}
+				n, err := optWhole(args, "lines", 0, 0, 40)
+				if err != nil {
+					return nil, err
+				}
+				ci, err := optFlag(args, "case_insensitive", true)
+				if err != nil {
+					return nil, err
+				}
+				timeout, err := optWhole(args, "timeout_seconds", 20, 1, MostWait)
+				if err != nil {
+					return nil, err
+				}
+				return Menu(Ask{Choices: choices, Prompt: prompt, Lines: n, CaseInsensitive: ci, Timeout: timeout})
+			},
+		},
+		{
+			Name:        "dmenu_session",
+			Description: "Which X session the menu would appear in and how it was found, or why there is none; and dmenu's version. (r)",
+			Input:       map[string]any{},
+			Run:         func(map[string]any) (any, error) { return SessionCheck() },
+		},
+	}
+}

modules/dmenu/cmd/dmenu-tools/manifest_kit_test.go

@@ -0,0 +1,107 @@
+package main
+
+// manifest_kit_test.go is the same file in each workstation module: it reads the module's
+// definition so the module's own tests can hold it to what it says.
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"testing"
+)
+
+type manifest struct {
+	Module       string           `json:"module"`
+	Capabilities []string         `json:"capabilities"`
+	Claims       []any            `json:"claims"`
+	Seats        []any            `json:"seats"`
+	Tools        []string         `json:"tools"`
+	Resources    []map[string]any `json:"resources"`
+	Build        struct {
+		Artifacts []map[string]any `json:"artifacts"`
+	} `json:"build"`
+}
+
+func readManifest(t *testing.T) manifest {
+	t.Helper()
+	raw, err := os.ReadFile(filepath.Join("..", "..", "module.json"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	var m manifest
+	if err := json.Unmarshal(raw, &m); err != nil {
+		t.Fatalf("module.json: %v", err)
+	}
+	return m
+}
+
+func (m manifest) resource(id string) map[string]any {
+	for _, r := range m.Resources {
+		if r["id"] == id {
+			return r
+		}
+	}
+	return nil
+}
+
+// packages are the packages the module installs, sorted.
+func (m manifest) packages() []string {
+	out := []string{}
+	for _, r := range m.Resources {
+		if r["type"] == "package" && r["absent"] != true {
+			out = append(out, r["package"].(string))
+		}
+	}
+	sort.Strings(out)
+	return out
+}
+
+// services are the units the module declares, by unit name.
+func (m manifest) services() map[string]map[string]any {
+	out := map[string]map[string]any{}
+	for _, r := range m.Resources {
+		if r["type"] == "service" {
+			out[r["unit"].(string)] = r
+		}
+	}
+	return out
+}
+
+// holdsTheBundle holds the manifest to the Go bundle this directory builds: every tool registered
+// is listed and nothing else, each named <prefix>_…, and the artifact builds this command.
+func holdsTheBundle(t *testing.T, m manifest, prefix string) {
+	t.Helper()
+	registered := []string{}
+	for _, tool := range tools() {
+		registered = append(registered, tool.Name)
+		if !strings.HasPrefix(tool.Name, prefix+"_") {
+			t.Errorf("tool %s is not named %s_…", tool.Name, prefix)
+		}
+		if tool.Description == "" || tool.Run == nil || tool.Input == nil {
+			t.Errorf("tool %s is not described, runnable and given an input schema", tool.Name)
+		}
+	}
+	if strings.Join(registered, ",") != strings.Join(m.Tools, ",") {
+		t.Errorf("registered %v, listed %v", registered, m.Tools)
+	}
+	if len(m.Build.Artifacts) != 1 {
+		t.Fatalf("one artifact, got %d", len(m.Build.Artifacts))
+	}
+	cwd, _ := os.Getwd()
+	binary := filepath.Base(cwd)
+	a := m.Build.Artifacts[0]
+	want := map[string]any{"kind": "bundle", "language": "go", "system": "arch", "from": "cmd/" + binary, "binary": binary}
+	for k, v := range want {
+		if a[k] != v {
+			t.Errorf("artifact %s = %v, want %v", k, a[k], v)
+		}
+	}
+	if loads, _ := a["loads"].([]any); len(loads) != 1 || loads[0] != binary {
+		t.Errorf("artifact loads %v, want [%s]", a["loads"], binary)
+	}
+	if m.Claims != nil || m.Seats != nil {
+		t.Errorf("claims %v, seats %v: this module holds no seat", m.Claims, m.Seats)
+	}
+}

modules/dmenu/cmd/dmenu-tools/session.go

@@ -0,0 +1,177 @@
+package main
+
+// session.go is the same file in the bundles whose tools act in the operator's graphical session
+// (xclip, dmenu): how a process the node's tool runtime launched reaches that session.
+//
+// The runtime is a system service running as the operator account (novox/hq ADR 0175 §4), in the
+// machine's own mount namespace, and is given no session words: no DISPLAY, no XAUTHORITY. An X
+// server accepts a client that names its display and presents the cookie in the authority file, and
+// both are the account's: the display's socket is in /tmp/.X11-unix, and the cookie file is
+// readable by the account. So the session is found, not configured:
+//
+//  1. the process's own DISPLAY, when the runtime happens to have one;
+//  2. else the DISPLAY and XAUTHORITY of the account's own running processes, read from
+//     /proc/<pid>/environ (the window manager's, by preference), whose socket exists;
+//  3. else the only X socket there is, with the authority file in the account's home.
+//
+// When none is found the tool says that no graphical session of the account is running, and does
+// nothing.
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+	"strconv"
+	"strings"
+	"syscall"
+)
+
+// Session is the operator's X session as a tool reaches it.
+type Session struct {
+	Display    string `json:"display"`
+	XAuthority string `json:"xauthority,omitempty"`
+	// FoundBy says how: "environment", "process <pid> (<name>)" or "socket".
+	FoundBy string `json:"found_by"`
+}
+
+// Env is what a command needs to reach the session.
+func (s Session) Env() []string {
+	env := []string{"DISPLAY=" + s.Display}
+	if s.XAuthority != "" {
+		env = append(env, "XAUTHORITY="+s.XAuthority)
+	}
+	return env
+}
+
+// Where the session is looked for. Tests point these at a tree of their own.
+var (
+	procRoot   = "/proc"
+	x11Sockets = "/tmp/.X11-unix"
+	getenv     = os.Getenv
+	myUID      = os.Getuid
+)
+
+// sessionWMs are the programs whose environment is the session's own, preferred over any other
+// process's (a terminal's child may carry a stale or forwarded DISPLAY).
+var sessionWMs = map[string]bool{"i3": true, "sway": true, "xinit": true, "i3bar": true, "picom": true, "dunst": true}
+
+func accountHome() string {
+	if h := strings.TrimSpace(getenv("MESH_OPERATOR_HOME")); h != "" {
+		return h
+	}
+	if h := strings.TrimSpace(getenv("HOME")); h != "" {
+		return h
+	}
+	h, _ := os.UserHomeDir()
+	return h
+}
+
+// socketOf is the local socket of a display such as ":1" or ":1.0", or "" for a remote one.
+func socketOf(display string) string {
+	if !strings.HasPrefix(display, ":") {
+		return ""
+	}
+	n := strings.TrimPrefix(display, ":")
+	if i := strings.IndexByte(n, '.'); i >= 0 {
+		n = n[:i]
+	}
+	if _, err := strconv.Atoi(n); err != nil {
+		return ""
+	}
+	return filepath.Join(x11Sockets, "X"+n)
+}
+
+func exists(p string) bool {
+	_, err := os.Stat(p)
+	return err == nil
+}
+
+// findSession answers the account's X session, or an error saying there is none.
+func findSession() (Session, error) {
+	if d := strings.TrimSpace(getenv("DISPLAY")); d != "" {
+		if s := socketOf(d); s == "" || exists(s) {
+			return Session{Display: d, XAuthority: getenv("XAUTHORITY"), FoundBy: "environment"}, nil
+		}
+	}
+	type seen struct {
+		Session
+		wm    bool
+		count int
+	}
+	found := map[string]*seen{}
+	entries, _ := os.ReadDir(procRoot)
+	for _, e := range entries {
+		pid, err := strconv.Atoi(e.Name())
+		if err != nil || !e.IsDir() {
+			continue
+		}
+		dir := filepath.Join(procRoot, e.Name())
+		info, err := os.Stat(dir)
+		if err != nil {
+			continue
+		}
+		if st, ok := info.Sys().(*syscall.Stat_t); !ok || int(st.Uid) != myUID() {
+			continue
+		}
+		raw, err := os.ReadFile(filepath.Join(dir, "environ"))
+		if err != nil {
+			continue
+		}
+		var display, auth string
+		for _, kv := range strings.Split(string(raw), "\x00") {
+			switch {
+			case strings.HasPrefix(kv, "DISPLAY="):
+				display = strings.TrimPrefix(kv, "DISPLAY=")
+			case strings.HasPrefix(kv, "XAUTHORITY="):
+				auth = strings.TrimPrefix(kv, "XAUTHORITY=")
+			}
+		}
+		if display == "" {
+			continue
+		}
+		if s := socketOf(display); s == "" || !exists(s) {
+			continue
+		}
+		comm, _ := os.ReadFile(filepath.Join(dir, "comm"))
+		name := strings.TrimSpace(string(comm))
+		key := display + "\x00" + auth
+		if found[key] == nil {
+			found[key] = &seen{Session: Session{Display: display, XAuthority: auth, FoundBy: fmt.Sprintf("process %d (%s)", pid, name)}}
+		}
+		f := found[key]
+		f.count++
+		if sessionWMs[name] && !f.wm {
+			f.wm = true
+			f.FoundBy = fmt.Sprintf("process %d (%s)", pid, name)
+		}
+	}
+	if len(found) > 0 {
+		all := make([]*seen, 0, len(found))
+		for _, f := range found {
+			all = append(all, f)
+		}
+		sort.Slice(all, func(i, k int) bool {
+			if all[i].wm != all[k].wm {
+				return all[i].wm
+			}
+			if all[i].count != all[k].count {
+				return all[i].count > all[k].count
+			}
+			return all[i].Display < all[k].Display
+		})
+		return all[0].Session, nil
+	}
+	sockets, _ := filepath.Glob(filepath.Join(x11Sockets, "X*"))
+	if len(sockets) == 1 {
+		s := Session{Display: ":" + strings.TrimPrefix(filepath.Base(sockets[0]), "X"), FoundBy: "socket"}
+		if a := filepath.Join(accountHome(), ".Xauthority"); exists(a) {
+			s.XAuthority = a
+		}
+		return s, nil
+	}
+	if len(sockets) > 1 {
+		return Session{}, fmt.Errorf("no process of this account names its X display, and there are %d X sockets in %s: which one is the operator's session cannot be told", len(sockets), x11Sockets)
+	}
+	return Session{}, fmt.Errorf("no graphical session of this account is running on this machine: no process of the account has DISPLAY set, and there is no X socket in %s. A desktop tool acts only while the operator is logged in to the graphical session", x11Sockets)
+}

modules/dmenu/cmd/dmenu-tools/session_test.go

@@ -0,0 +1,94 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"testing"
+)
+
+// aMachine gives findSession a /proc and an X socket directory of the test's own.
+func aMachine(t *testing.T, env map[string]string) (proc, sockets string) {
+	t.Helper()
+	root := t.TempDir()
+	proc, sockets = filepath.Join(root, "proc"), filepath.Join(root, "x11")
+	for _, d := range []string{proc, sockets} {
+		if err := os.MkdirAll(d, 0o755); err != nil {
+			t.Fatal(err)
+		}
+	}
+	wasProc, wasX, wasEnv := procRoot, x11Sockets, getenv
+	procRoot, x11Sockets = proc, sockets
+	getenv = func(k string) string { return env[k] }
+	t.Cleanup(func() { procRoot, x11Sockets, getenv = wasProc, wasX, wasEnv })
+	return proc, sockets
+}
+
+func aProcess(t *testing.T, proc string, pid int, comm string, env ...string) {
+	t.Helper()
+	dir := filepath.Join(proc, strconv.Itoa(pid))
+	if err := os.MkdirAll(dir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	_ = os.WriteFile(filepath.Join(dir, "comm"), []byte(comm+"\n"), 0o644)
+	_ = os.WriteFile(filepath.Join(dir, "environ"), []byte(strings.Join(env, "\x00")+"\x00"), 0o644)
+}
+
+func aSocket(t *testing.T, dir, name string) {
+	t.Helper()
+	if err := os.WriteFile(filepath.Join(dir, name), nil, 0o644); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestSessionTheWindowManagersDisplayAndCookieAreTheSessions(t *testing.T) {
+	proc, sockets := aMachine(t, map[string]string{"MESH_OPERATOR_HOME": "/home/op"})
+	aSocket(t, sockets, "X1")
+	aProcess(t, proc, 3, "bash", "DISPLAY=:9", "XAUTHORITY=/stale")
+	aProcess(t, proc, 4, "kitty", "DISPLAY=:1", "XAUTHORITY=/home/op/.Xauthority")
+	aProcess(t, proc, 5, "i3", "DISPLAY=:1.0", "XAUTHORITY=/home/op/.Xauthority")
+	aProcess(t, proc, 6, "sshd", "PATH=/bin")
+	s, err := findSession()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if s.Display != ":1.0" || s.XAuthority != "/home/op/.Xauthority" || !strings.Contains(s.FoundBy, "i3") {
+		t.Fatalf("%+v: a display without a socket (:9) is skipped, and the window manager's is preferred", s)
+	}
+	if got := strings.Join(s.Env(), " "); got != "DISPLAY=:1.0 XAUTHORITY=/home/op/.Xauthority" {
+		t.Fatalf("env %s", got)
+	}
+}
+
+func TestSessionTheOnlySocketWithTheHomesCookieIsTheFallback(t *testing.T) {
+	home := t.TempDir()
+	_ = os.WriteFile(filepath.Join(home, ".Xauthority"), []byte("c"), 0o600)
+	_, sockets := aMachine(t, map[string]string{"MESH_OPERATOR_HOME": home})
+	aSocket(t, sockets, "X0")
+	s, err := findSession()
+	if err != nil || s.Display != ":0" || s.XAuthority != filepath.Join(home, ".Xauthority") || s.FoundBy != "socket" {
+		t.Fatalf("%+v %v", s, err)
+	}
+}
+
+func TestSessionNoSessionIsSaidNotGuessed(t *testing.T) {
+	_, sockets := aMachine(t, map[string]string{})
+	if _, err := findSession(); err == nil || !strings.Contains(err.Error(), "no graphical session") {
+		t.Fatalf("none: %v", err)
+	}
+	aSocket(t, sockets, "X0")
+	aSocket(t, sockets, "X1")
+	if _, err := findSession(); err == nil || !strings.Contains(err.Error(), "2 X sockets") {
+		t.Fatalf("two: %v", err)
+	}
+}
+
+func TestSessionTheProcessesOwnDisplayComesFirst(t *testing.T) {
+	_, sockets := aMachine(t, map[string]string{"DISPLAY": ":2", "XAUTHORITY": "/a"})
+	aSocket(t, sockets, "X2")
+	s, err := findSession()
+	if err != nil || s.Display != ":2" || s.FoundBy != "environment" {
+		t.Fatalf("%+v %v", s, err)
+	}
+}

modules/dmenu/go.mod

@@ -0,0 +1,5 @@
+module dmenu
+
+go 1.22
+
+require git.novox.be/novox/mesh-sdk/go v0.1.6

modules/dmenu/go.sum

@@ -0,0 +1,2 @@
+git.novox.be/novox/mesh-sdk/go v0.1.6 h1:9qzdYONYbJdWcu6sxQcq9v1LI0JxcfkiKYkMUzJSkVQ=
+git.novox.be/novox/mesh-sdk/go v0.1.6/go.mod h1:GFuZUElBZ9A++mxgIKo97aXXo+kV0uJ/UkbhQPPIbrY=

modules/dmenu/module.json

@@ -0,0 +1,33 @@
+{
+  "module": "dmenu",
+  "version": "1",
+  "capabilities": [
+    "package-manager"
+  ],
+  "tools": [
+    "dmenu_menu",
+    "dmenu_session"
+  ],
+  "resources": [
+    {
+      "id": "package",
+      "type": "package",
+      "package": "dmenu"
+    }
+  ],
+  "build": {
+    "artifacts": [
+      {
+        "name": "tools",
+        "kind": "bundle",
+        "language": "go",
+        "system": "arch",
+        "from": "cmd/dmenu-tools",
+        "binary": "dmenu-tools",
+        "loads": [
+          "dmenu-tools"
+        ]
+      }
+    ]
+  }
+}

modules/docker-compose/README.md

@@ -0,0 +1,65 @@
+# docker-compose
+
+Compose, for development work on the two workstations (novox/hq research 027/02: "the distribution's
+package and nothing else", assigned only to the workstations; to-be 42 phase 2 step 9). The servers
+run nothing through compose.
+
+## Owns
+
+| what | where |
+|---|---|
+| compose, as the container runtime's plugin (`docker compose`) and as `docker-compose` | package `docker-compose` |
+
+Nothing else. The runtime, its configuration, buildx and the `docker` group are the `docker` module's
+(to-be 42 phase 1 step 8). This module needs that runtime on the machine. Until the `docker` module
+holds `node-container-runtime` there, nothing in the mesh says so, and the tools answer that the
+runtime is missing or unreachable rather than an empty list.
+
+## Improves
+
+- **An owner for a package both workstations already carry.** On both, `docker-compose` 5.5.0 is
+  installed explicitly by hand, as the plugin in `/usr/lib/docker/cli-plugins`. Assigning the module
+  changes nothing on disk; from then on the package is the mesh's, upgraded with the machine and
+  given back when the module goes.
+- **The projects become visible from the mesh** without a shell on the machine: which are running,
+  where their files are, their containers, logs and rendered configuration.
+- **No account-level copy of the plugin** exists on either workstation (`~/.docker/cli-plugins` is
+  empty), so there is no second compose to remove.
+
+## Tools
+
+All answer JSON; `(r)` reads, `(a)` acts. They run as the operator account, which reaches the runtime
+through the `docker` group. Nothing goes through `sudo`.
+
+A project is named by `dir`, its absolute directory, or by `project`, its name. A directory docker
+already knows a project for is that project, with the files it was started from, overrides included.
+Any other directory must hold a compose file.
+
+| tool | what |
+|---|---|
+| `docker_compose_projects` (r) | every project docker knows, running or stopped: status, working directory (from the containers' labels), compose files, services, containers running of total |
+| `docker_compose_ps` (r) | one project's containers: service, state, health, exit code, image, published ports |
+| `docker_compose_logs` (r) | the last lines per service (default 200, at most 5000), optionally `since`; cut at 256 KiB |
+| `docker_compose_config` (r) | the rendered configuration. Values of environment variables, build arguments and labels whose names suggest a secret, and inline secret or config content, are replaced with `[redacted]`, and the answer counts them |
+| `docker_compose_up` (a) | `up --detach`, with the pull policy (default `missing`) and optionally `--build`, for all or some services |
+| `docker_compose_down` (a) | `down`: containers and networks. **Volumes are kept**: no tool here removes data |
+| `docker_compose_restart` (a) | restart all or some services |
+| `docker_compose_pull` (a) | pull images without starting anything |
+| `docker_compose_job` (r) | a long act's state: running or finished, exit status, the end of its output; without an id, every act this process knows |
+
+**Acts are jobs.** An `up` that pulls or builds takes minutes, and the runtime gives a call 30 s. Each
+act runs inside the tool's process for up to 15 minutes, and is waited on for 18 s. A finished act is
+answered with its output, and a failed one as an error. One still running is answered with its job id,
+which `docker_compose_job` follows. A job ends if the runtime restarts the bundle.
+
+## Leaves as found
+
+The projects themselves are the operator's work, under the operator's directories. Measured on
+2026-10-04:
+
+- **laptop:** `anton-lavinmq` and `anton-traefik` running, `anton-redis` stopped.
+- **desktop:** `anton-lavinmq`, `lavinmq` (from `/services/lavinmq`, a predecessor's directory) and
+  `registry` running.
+
+Whether the desktop's `lavinmq` and `registry` should still run is the operator's call;
+`docker_compose_down` with their directory stops them.

modules/docker-compose/cmd/docker-compose-tools/compose.go

@@ -0,0 +1,455 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"regexp"
+	"sort"
+	"strings"
+)
+
+// Project is one compose project as docker knows it.
+type Project struct {
+	Name        string   `json:"name"`
+	Status      string   `json:"status,omitempty"`
+	WorkingDir  string   `json:"working_dir,omitempty"`
+	ConfigFiles []string `json:"config_files"`
+	Services    []string `json:"services"`
+	Running     int      `json:"running"`
+	Containers  int      `json:"containers"`
+}
+
+// ProjectsAnswer is what docker_compose_projects answers.
+type ProjectsAnswer struct {
+	Count    int       `json:"count"`
+	Projects []Project `json:"projects"`
+}
+
+// composeFiles are the names compose looks for in a directory, in its order.
+var composeFiles = []string{"compose.yaml", "compose.yml", "docker-compose.yaml", "docker-compose.yml"}
+
+// statDir says whether a path is a directory. Tests replace it.
+var statDir = func(p string) bool {
+	info, err := os.Stat(p)
+	return err == nil && info.IsDir()
+}
+
+// statFile says whether a path is a regular file. Tests replace it.
+var statFile = func(p string) bool {
+	info, err := os.Stat(p)
+	return err == nil && info.Mode().IsRegular()
+}
+
+// docker runs one docker command and names a daemon the account cannot reach as such.
+func docker(args ...string) (Result, error) {
+	r, err := call(Cmd{Name: "docker", Args: args})
+	if err != nil && strings.Contains(r.Stderr, "permission denied") && strings.Contains(r.Stderr, "docker.sock") {
+		return r, fmt.Errorf("the account cannot reach the container runtime's socket (permission denied): it is not in the docker group, or has not logged in since it was added. The docker module owns the group's members")
+	}
+	if err != nil && strings.Contains(r.Stderr, "Cannot connect to the Docker daemon") {
+		return r, fmt.Errorf("the container runtime is not running on this machine: %s", firstLine(r.Stderr))
+	}
+	return r, err
+}
+
+// Projects merges what compose lists with what the containers' labels say.
+func Projects() (ProjectsAnswer, error) {
+	r, err := docker("compose", "ls", "--all", "--format", "json")
+	if err != nil {
+		return ProjectsAnswer{}, err
+	}
+	var listed []struct {
+		Name        string `json:"Name"`
+		Status      string `json:"Status"`
+		ConfigFiles string `json:"ConfigFiles"`
+	}
+	if s := strings.TrimSpace(r.Stdout); s != "" {
+		if err := json.Unmarshal([]byte(s), &listed); err != nil {
+			return ProjectsAnswer{}, fmt.Errorf("docker compose ls answered what is not JSON: %v", err)
+		}
+	}
+	by := map[string]*Project{}
+	get := func(name string) *Project {
+		if by[name] == nil {
+			by[name] = &Project{Name: name, ConfigFiles: []string{}, Services: []string{}}
+		}
+		return by[name]
+	}
+	for _, l := range listed {
+		p := get(l.Name)
+		p.Status = l.Status
+		p.ConfigFiles = splitFiles(l.ConfigFiles)
+	}
+	r, err = docker("ps", "-a", "--filter", "label=com.docker.compose.project", "--format",
+		`{{.Label "com.docker.compose.project"}}`+"\t"+`{{.Label "com.docker.compose.project.working_dir"}}`+"\t"+
+			`{{.Label "com.docker.compose.project.config_files"}}`+"\t"+`{{.Label "com.docker.compose.service"}}`+"\t{{.State}}")
+	if err != nil {
+		return ProjectsAnswer{}, err
+	}
+	services := map[string]map[string]bool{}
+	for _, l := range lines(r.Stdout) {
+		f := strings.Split(l, "\t")
+		if len(f) < 5 || f[0] == "" {
+			continue
+		}
+		p := get(f[0])
+		if p.WorkingDir == "" {
+			p.WorkingDir = f[1]
+		}
+		if len(p.ConfigFiles) == 0 {
+			p.ConfigFiles = splitFiles(f[2])
+		}
+		if services[f[0]] == nil {
+			services[f[0]] = map[string]bool{}
+		}
+		if f[3] != "" {
+			services[f[0]][f[3]] = true
+		}
+		p.Containers++
+		if f[4] == "running" {
+			p.Running++
+		}
+	}
+	out := ProjectsAnswer{Projects: []Project{}}
+	for name, p := range by {
+		for s := range services[name] {
+			p.Services = append(p.Services, s)
+		}
+		sort.Strings(p.Services)
+		if p.WorkingDir == "" && len(p.ConfigFiles) > 0 {
+			p.WorkingDir = filepath.Dir(p.ConfigFiles[0])
+		}
+		out.Projects = append(out.Projects, *p)
+	}
+	sort.Slice(out.Projects, func(i, k int) bool { return out.Projects[i].Name < out.Projects[k].Name })
+	out.Count = len(out.Projects)
+	return out, nil
+}
+
+func splitFiles(s string) []string {
+	out := []string{}
+	for _, f := range strings.Split(s, ",") {
+		if f = strings.TrimSpace(f); f != "" {
+			out = append(out, f)
+		}
+	}
+	return out
+}
+
+// Target is the project a tool acts on, and how compose is told which it is.
+type Target struct {
+	Project string   `json:"project,omitempty"`
+	Dir     string   `json:"dir,omitempty"`
+	Files   []string `json:"files,omitempty"`
+}
+
+// args are compose's own options naming the target.
+func (t Target) args() []string {
+	out := []string{"compose"}
+	if t.Dir != "" {
+		out = append(out, "--project-directory", t.Dir)
+	}
+	for _, f := range t.Files {
+		out = append(out, "-f", f)
+	}
+	if t.Project != "" {
+		out = append(out, "-p", t.Project)
+	}
+	return out
+}
+
+var projectName = regexp.MustCompile(`^[a-z0-9][a-z0-9_-]*$`)
+
+// targetOf reads dir or project. A directory docker already knows a project for is that project,
+// with the files it was started from; otherwise it must hold a compose file. needFiles says the
+// tool reads the files (config, up, pull), so a project known only by its containers is not enough.
+func targetOf(args map[string]any, needFiles bool) (Target, error) {
+	dir, err := optText(args, "dir", "")
+	if err != nil {
+		return Target{}, err
+	}
+	name, err := optText(args, "project", "")
+	if err != nil {
+		return Target{}, err
+	}
+	if dir == "" && name == "" {
+		return Target{}, fmt.Errorf("give dir, the project's directory, or project, its name")
+	}
+	if dir != "" {
+		if !filepath.IsAbs(dir) {
+			return Target{}, fmt.Errorf("dir must be an absolute path, not %q", dir)
+		}
+		dir = filepath.Clean(dir)
+		if !statDir(dir) {
+			return Target{}, fmt.Errorf("%s is not a directory on this machine", dir)
+		}
+	}
+	if name != "" && !projectName.MatchString(name) {
+		return Target{}, fmt.Errorf("%q is not a compose project name", name)
+	}
+	known, err := Projects()
+	if err != nil {
+		return Target{}, err
+	}
+	for _, p := range known.Projects {
+		if (dir != "" && p.WorkingDir == dir) || (dir == "" && p.Name == name) {
+			if name != "" && p.Name != name {
+				continue
+			}
+			t := Target{Project: p.Name, Dir: p.WorkingDir}
+			present := len(p.ConfigFiles) > 0
+			for _, f := range p.ConfigFiles {
+				present = present && statFile(f)
+			}
+			if present {
+				t.Files = p.ConfigFiles
+			} else if needFiles && !hasComposeFile(t.Dir) {
+				return Target{}, fmt.Errorf("project %s was started from %s, which is no longer there", p.Name, strings.Join(p.ConfigFiles, ", "))
+			}
+			return t, nil
+		}
+	}
+	if dir == "" {
+		return Target{}, fmt.Errorf("no compose project named %s is known to docker here: give dir, its directory", name)
+	}
+	if !hasComposeFile(dir) {
+		return Target{}, fmt.Errorf("%s holds no compose file (%s)", dir, strings.Join(composeFiles, ", "))
+	}
+	return Target{Dir: dir, Project: name}, nil
+}
+
+func hasComposeFile(dir string) bool {
+	for _, f := range composeFiles {
+		if statFile(filepath.Join(dir, f)) {
+			return true
+		}
+	}
+	return false
+}
+
+// Container is one of a project's containers.
+type Container struct {
+	Name     string   `json:"name"`
+	Service  string   `json:"service"`
+	State    string   `json:"state"`
+	Status   string   `json:"status"`
+	Health   string   `json:"health,omitempty"`
+	ExitCode int      `json:"exit_code"`
+	Image    string   `json:"image"`
+	Ports    []string `json:"ports"`
+}
+
+// PsAnswer is what docker_compose_ps answers.
+type PsAnswer struct {
+	Target     Target      `json:"target"`
+	Containers []Container `json:"containers"`
+}
+
+// jsonObjects reads compose's JSON output, which is one array or one object per line by version.
+func jsonObjects(s string, into any) error {
+	s = strings.TrimSpace(s)
+	if s == "" {
+		s = "[]"
+	}
+	if !strings.HasPrefix(s, "[") {
+		s = "[" + strings.Join(lines(s), ",") + "]"
+	}
+	return json.Unmarshal([]byte(s), into)
+}
+
+// Ps answers a project's containers.
+func Ps(t Target) (PsAnswer, error) {
+	r, err := docker(append(t.args(), "ps", "-a", "--format", "json")...)
+	if err != nil {
+		return PsAnswer{}, err
+	}
+	var raw []struct {
+		Name       string `json:"Name"`
+		Service    string `json:"Service"`
+		State      string `json:"State"`
+		Status     string `json:"Status"`
+		Health     string `json:"Health"`
+		ExitCode   int    `json:"ExitCode"`
+		Image      string `json:"Image"`
+		Publishers []struct {
+			URL           string `json:"URL"`
+			TargetPort    int    `json:"TargetPort"`
+			PublishedPort int    `json:"PublishedPort"`
+			Protocol      string `json:"Protocol"`
+		} `json:"Publishers"`
+	}
+	if err := jsonObjects(r.Stdout, &raw); err != nil {
+		return PsAnswer{}, fmt.Errorf("docker compose ps answered what is not JSON: %v", err)
+	}
+	out := PsAnswer{Target: t, Containers: []Container{}}
+	for _, c := range raw {
+		ports := []string{}
+		for _, p := range c.Publishers {
+			if p.PublishedPort == 0 {
+				continue
+			}
+			ports = append(ports, fmt.Sprintf("%s:%d->%d/%s", p.URL, p.PublishedPort, p.TargetPort, p.Protocol))
+		}
+		out.Containers = append(out.Containers, Container{Name: c.Name, Service: c.Service, State: c.State, Status: c.Status,
+			Health: c.Health, ExitCode: c.ExitCode, Image: c.Image, Ports: ports})
+	}
+	return out, nil
+}
+
+// LogsAnswer is what docker_compose_logs answers.
+type LogsAnswer struct {
+	Target    Target   `json:"target"`
+	Lines     []string `json:"lines"`
+	Truncated bool     `json:"truncated,omitempty"`
+}
+
+var since = regexp.MustCompile(`^[0-9A-Za-z:.+-]+$`)
+
+// Logs answers a project's last lines.
+func Logs(t Target, services []string, n int, from string) (LogsAnswer, error) {
+	args := append(t.args(), "logs", "--no-color", "--timestamps", "--tail", fmt.Sprint(n))
+	if from != "" {
+		if !since.MatchString(from) {
+			return LogsAnswer{}, fmt.Errorf("since %q is neither a duration nor a timestamp", from)
+		}
+		args = append(args, "--since", from)
+	}
+	for _, s := range services {
+		if err := plainName("service", s); err != nil {
+			return LogsAnswer{}, err
+		}
+	}
+	r, err := docker(append(args, services...)...)
+	if err != nil {
+		return LogsAnswer{}, err
+	}
+	// compose writes the containers' output on its stdout, and its own complaints on stderr.
+	return LogsAnswer{Target: t, Lines: lines(r.Stdout), Truncated: r.Truncated}, nil
+}
+
+// ConfigAnswer is what docker_compose_config answers.
+type ConfigAnswer struct {
+	Target   Target         `json:"target"`
+	Services []string       `json:"services"`
+	Redacted int            `json:"redacted"`
+	Rendered map[string]any `json:"rendered"`
+}
+
+// secretish is a name whose value is not shown.
+var secretish = regexp.MustCompile(`(?i)(pass|secret|token|key|credential|auth|private|cert|cookie|session|salt|dsn|api)`)
+
+// redact replaces the values of secret-looking names in the maps compose renders.
+func redact(v any, count *int) {
+	switch x := v.(type) {
+	case map[string]any:
+		for k, child := range x {
+			switch k {
+			case "environment", "args", "labels", "build_args":
+				if m, ok := child.(map[string]any); ok {
+					for name, val := range m {
+						if val != nil && secretish.MatchString(name) {
+							m[name] = "[redacted]"
+							*count++
+						}
+					}
+					continue
+				}
+			case "content":
+				// An inline config or secret: its content is the secret itself.
+				if _, ok := child.(string); ok {
+					x[k] = "[redacted]"
+					*count++
+					continue
+				}
+			}
+			redact(child, count)
+		}
+	case []any:
+		for _, child := range x {
+			redact(child, count)
+		}
+	}
+}
+
+// Config answers the rendered configuration.
+func Config(t Target) (ConfigAnswer, error) {
+	r, err := docker(append(t.args(), "config", "--format", "json")...)
+	if err != nil {
+		return ConfigAnswer{}, err
+	}
+	var rendered map[string]any
+	if err := json.Unmarshal([]byte(r.Stdout), &rendered); err != nil {
+		return ConfigAnswer{}, fmt.Errorf("docker compose config answered what is not JSON: %v", err)
+	}
+	out := ConfigAnswer{Target: t, Services: []string{}, Rendered: rendered}
+	if s, ok := rendered["services"].(map[string]any); ok {
+		for name := range s {
+			out.Services = append(out.Services, name)
+		}
+		sort.Strings(out.Services)
+	}
+	redact(rendered, &out.Redacted)
+	return out, nil
+}
+
+// ActAnswer is what an act answers: the target and the job that carries it.
+type ActAnswer struct {
+	Act    string `json:"act"`
+	Target Target `json:"target"`
+	Job    Job    `json:"job"`
+}
+
+func act(name string, t Target, extra ...string) (ActAnswer, error) {
+	j, err := actAsJob(Cmd{Name: "docker", Args: append(append(t.args(), name), extra...)})
+	if err != nil {
+		return ActAnswer{}, err
+	}
+	return ActAnswer{Act: name, Target: t, Job: j}, nil
+}
+
+func checkServices(services []string) error {
+	for _, s := range services {
+		if err := plainName("service", s); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// Up brings a project up, detached.
+func Up(t Target, services []string, build bool, pull string) (ActAnswer, error) {
+	if err := oneOf("pull", pull, "missing", "always", "never"); err != nil {
+		return ActAnswer{}, err
+	}
+	if err := checkServices(services); err != nil {
+		return ActAnswer{}, err
+	}
+	extra := []string{"--detach", "--pull", pull}
+	if build {
+		extra = append(extra, "--build")
+	}
+	return act("up", t, append(extra, services...)...)
+}
+
+// Down stops and removes a project's containers and networks, keeping its volumes.
+func Down(t Target) (ActAnswer, error) {
+	return act("down", t)
+}
+
+// Restart restarts a project's containers.
+func Restart(t Target, services []string) (ActAnswer, error) {
+	if err := checkServices(services); err != nil {
+		return ActAnswer{}, err
+	}
+	return act("restart", t, services...)
+}
+
+// Pull pulls a project's images.
+func Pull(t Target, services []string) (ActAnswer, error) {
+	if err := checkServices(services); err != nil {
+		return ActAnswer{}, err
+	}
+	return act("pull", t, services...)
+}

modules/docker-compose/cmd/docker-compose-tools/compose_test.go

@@ -0,0 +1,222 @@
+package main
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+)
+
+func TestTheManifestIsComposesPackageAndNothingElse(t *testing.T) {
+	m := readManifest(t)
+	holdsTheBundle(t, m, "docker_compose")
+	if got := strings.Join(m.packages(), ","); got != "docker-compose" {
+		t.Errorf("packages %s: buildx and the runtime are the docker module's", got)
+	}
+	if len(m.Resources) != 1 {
+		t.Errorf("one resource, the package: %v", m.Resources)
+	}
+}
+
+const lsJSON = `[{"Name":"anton-lavinmq","Status":"running(1)","ConfigFiles":"/home/op/hub/lavinmq/docker-compose.yml"},{"Name":"old","Status":"exited(2)","ConfigFiles":"/srv/old/compose.yaml,/srv/old/compose.override.yaml"}]`
+
+const psLabels = "anton-lavinmq\t/home/op/hub/lavinmq\t/home/op/hub/lavinmq/docker-compose.yml\tlavinmq\trunning\n" +
+	"old\t/srv/old\t/srv/old/compose.yaml,/srv/old/compose.override.yaml\tweb\texited\n" +
+	"old\t/srv/old\t/srv/old/compose.yaml,/srv/old/compose.override.yaml\tdb\texited\n"
+
+// aDocker answers compose ls and the labelled ps, and hands every other line to rest.
+func aDocker(t *testing.T, rest func(line string) Result) *fake {
+	return using(t, func(line string, c Cmd) Result {
+		switch {
+		case strings.HasPrefix(line, "docker compose ls"):
+			return ok(lsJSON)
+		case strings.HasPrefix(line, "docker ps -a --filter label=com.docker.compose.project"):
+			return ok(psLabels)
+		}
+		if rest != nil {
+			return rest(line)
+		}
+		return ok("")
+	})
+}
+
+func onDisk(t *testing.T, dirs, files []string) {
+	t.Helper()
+	wasD, wasF := statDir, statFile
+	in := func(set []string) func(string) bool {
+		return func(p string) bool {
+			for _, s := range set {
+				if s == p {
+					return true
+				}
+			}
+			return false
+		}
+	}
+	statDir, statFile = in(dirs), in(files)
+	t.Cleanup(func() { statDir, statFile = wasD, wasF })
+}
+
+func TestProjectsMergesComposesListWithTheContainersLabels(t *testing.T) {
+	aDocker(t, nil)
+	got, err := Projects()
+	if err != nil || got.Count != 2 {
+		t.Fatalf("%+v %v", got, err)
+	}
+	p := got.Projects[0]
+	if p.Name != "anton-lavinmq" || p.WorkingDir != "/home/op/hub/lavinmq" || p.Running != 1 || p.Containers != 1 || p.Status != "running(1)" {
+		t.Errorf("%+v", p)
+	}
+	o := got.Projects[1]
+	if strings.Join(o.Services, ",") != "db,web" || len(o.ConfigFiles) != 2 || o.Running != 0 || o.Containers != 2 {
+		t.Errorf("%+v", o)
+	}
+}
+
+func TestProjectsNamesADaemonTheAccountCannotReach(t *testing.T) {
+	using(t, func(string, Cmd) Result {
+		return Result{Status: 1, Stderr: "permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock"}
+	})
+	if _, err := Projects(); err == nil || !strings.Contains(err.Error(), "docker group") {
+		t.Fatalf("%v", err)
+	}
+}
+
+func TestATargetIsAKnownProjectWithItsFilesOrADirectoryHoldingAComposeFile(t *testing.T) {
+	aDocker(t, nil)
+	onDisk(t, []string{"/home/op/hub/lavinmq", "/srv/new", "/srv/empty", "/srv/old"},
+		[]string{"/home/op/hub/lavinmq/docker-compose.yml", "/srv/new/compose.yaml"})
+	got, err := targetOf(map[string]any{"dir": "/home/op/hub/lavinmq/"}, true)
+	if err != nil || got.Project != "anton-lavinmq" || len(got.Files) != 1 {
+		t.Fatalf("a known directory: %+v %v", got, err)
+	}
+	if a := strings.Join(got.args(), " "); a != "compose --project-directory /home/op/hub/lavinmq -f /home/op/hub/lavinmq/docker-compose.yml -p anton-lavinmq" {
+		t.Errorf("args %s", a)
+	}
+	got, err = targetOf(map[string]any{"dir": "/srv/new"}, true)
+	if err != nil || got.Project != "" || got.Dir != "/srv/new" {
+		t.Fatalf("a new directory: %+v %v", got, err)
+	}
+	got, err = targetOf(map[string]any{"project": "old"}, false)
+	if err != nil || got.Dir != "/srv/old" || got.Files != nil {
+		t.Fatalf("a project whose files are gone, for an act that needs none: %+v %v", got, err)
+	}
+	if _, err := targetOf(map[string]any{"project": "old"}, true); err == nil || !strings.Contains(err.Error(), "no longer there") {
+		t.Errorf("its files are needed: %v", err)
+	}
+	for _, bad := range []map[string]any{{}, {"dir": "rel/path"}, {"dir": "/nope"}, {"dir": "/srv/empty"}, {"project": "Bad Name"}, {"project": "unknown"}} {
+		if _, err := targetOf(bad, false); err == nil {
+			t.Errorf("%v was accepted", bad)
+		}
+	}
+}
+
+func TestPsReadsEitherJSONShapeAndKeepsOnlyPublishedPorts(t *testing.T) {
+	aDocker(t, func(line string) Result {
+		return ok(`{"Name":"a-web-1","Service":"web","State":"running","Status":"Up 2 hours","Health":"healthy","ExitCode":0,"Image":"nginx","Publishers":[{"URL":"0.0.0.0","TargetPort":80,"PublishedPort":8080,"Protocol":"tcp"},{"URL":"","TargetPort":443,"PublishedPort":0,"Protocol":"tcp"}]}
+{"Name":"a-db-1","Service":"db","State":"exited","Status":"Exited (1)","ExitCode":1,"Image":"postgres","Publishers":[]}`)
+	})
+	got, err := Ps(Target{Project: "a"})
+	if err != nil || len(got.Containers) != 2 {
+		t.Fatalf("%+v %v", got, err)
+	}
+	if c := got.Containers[0]; strings.Join(c.Ports, ",") != "0.0.0.0:8080->80/tcp" || c.Health != "healthy" {
+		t.Errorf("%+v", c)
+	}
+	var arr []map[string]any
+	if err := jsonObjects(`[{"Name":"x"}]`, &arr); err != nil || len(arr) != 1 {
+		t.Errorf("an array: %v %v", arr, err)
+	}
+}
+
+func TestLogsAreBoundedAndRefuseAnOptionInAName(t *testing.T) {
+	f := aDocker(t, func(line string) Result { return Result{Stdout: "web-1 | a\nweb-1 | b\n", Truncated: true} })
+	got, err := Logs(Target{Project: "a"}, []string{"web"}, 50, "10m")
+	if err != nil || len(got.Lines) != 2 || !got.Truncated {
+		t.Fatalf("%+v %v", got, err)
+	}
+	if l := f.lines()[0]; l != "docker compose -p a logs --no-color --timestamps --tail 50 --since 10m web" {
+		t.Errorf("%s", l)
+	}
+	if _, err := Logs(Target{Project: "a"}, []string{"--follow"}, 5, ""); err == nil {
+		t.Error("an option as a service")
+	}
+	if _, err := Logs(Target{Project: "a"}, nil, 5, "1h; rm"); err == nil {
+		t.Error("a since that is neither")
+	}
+}
+
+func TestConfigRedactsSecretLookingValuesAndInlineContent(t *testing.T) {
+	aDocker(t, func(string) Result {
+		return ok(`{"name":"a","services":{"web":{"image":"nginx","environment":{"DB_PASSWORD":"hunter2","PORT":"80","API_TOKEN":"t"},"build":{"args":{"NPM_TOKEN":"n","NODE_ENV":"production"}}}},"secrets":{"s":{"content":"raw"}}}`)
+	})
+	got, err := Config(Target{Dir: "/srv/a"})
+	if err != nil || got.Redacted != 4 || strings.Join(got.Services, ",") != "web" {
+		t.Fatalf("%+v %v", got, err)
+	}
+	raw, _ := json.Marshal(got.Rendered)
+	for _, secret := range []string{"hunter2", `"t"`, `"n"`, "raw"} {
+		if strings.Contains(string(raw), secret) {
+			t.Errorf("%s shown: %s", secret, raw)
+		}
+	}
+	for _, kept := range []string{`"PORT":"80"`, `"NODE_ENV":"production"`, `"image":"nginx"`} {
+		if !strings.Contains(string(raw), kept) {
+			t.Errorf("%s hidden: %s", kept, raw)
+		}
+	}
+}
+
+func TestConfigAnInvalidFileIsComposesError(t *testing.T) {
+	aDocker(t, func(string) Result {
+		return Result{Status: 15, Stderr: "services.web Additional property foo is not allowed"}
+	})
+	if _, err := Config(Target{Dir: "/srv/a"}); err == nil || !strings.Contains(err.Error(), "Additional property") {
+		t.Fatalf("%v", err)
+	}
+}
+
+func TestActsAreJobsAsTheAccountKeepVolumesAndCheckTheirArguments(t *testing.T) {
+	f := aDocker(t, nil)
+	tg := Target{Dir: "/srv/a", Project: "a"}
+	if got, err := Up(tg, []string{"web"}, true, "always"); err != nil || got.Job.Running || got.Act != "up" {
+		t.Fatalf("%+v %v", got, err)
+	}
+	if _, err := Down(tg); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := Restart(tg, nil); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := Pull(tg, nil); err != nil {
+		t.Fatal(err)
+	}
+	want := []string{
+		"docker compose --project-directory /srv/a -p a up --detach --pull always --build web",
+		"docker compose --project-directory /srv/a -p a down",
+		"docker compose --project-directory /srv/a -p a restart",
+		"docker compose --project-directory /srv/a -p a pull",
+	}
+	if got := strings.Join(f.lines(), "\n"); got != strings.Join(want, "\n") {
+		t.Errorf("asked\n%s\nwant\n%s", got, strings.Join(want, "\n"))
+	}
+	for _, l := range f.lines() {
+		if strings.Contains(l, "sudo") || strings.Contains(l, "-v") || strings.Contains(l, "--volumes") {
+			t.Errorf("%s", l)
+		}
+	}
+	if _, err := Up(tg, nil, false, "sometimes"); err == nil {
+		t.Error("an unknown pull policy")
+	}
+	if _, err := Restart(tg, []string{"-t"}); err == nil {
+		t.Error("an option as a service")
+	}
+}
+
+func TestAFailedActIsAnError(t *testing.T) {
+	aDocker(t, func(string) Result {
+		return Result{Status: 1, Stderr: "Error response from daemon: port is already allocated"}
+	})
+	if _, err := Up(Target{Dir: "/srv/a"}, nil, false, "missing"); err == nil || !strings.Contains(err.Error(), "already allocated") {
+		t.Fatalf("%v", err)
+	}
+}

modules/docker-compose/cmd/docker-compose-tools/jobs.go

@@ -0,0 +1,151 @@
+package main
+
+// jobs.go is the same file in the bundles whose acts can outlast one call (flatpak, docker-compose):
+// an install or an `up` that pulls images takes minutes, and the runtime gives a call 30 s. Such an
+// act is started as a job inside this process, waited on for a while, and answered either finished
+// or with the job's id for the module's `_job` tool to follow. A job ends with this process: if the
+// runtime restarts the bundle, a running job is cut off, and its id is then unknown.
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+	"sync"
+	"time"
+)
+
+// JobLimit is the longest a job may run; JobWait how long an act waits before answering a job id.
+const (
+	JobLimit = 15 * time.Minute
+	JobWait  = 18 * time.Second
+	keptJobs = 50
+)
+
+// Job is one long act, as its tool answers it.
+type Job struct {
+	ID        string     `json:"job"`
+	Command   string     `json:"command"`
+	Started   time.Time  `json:"started"`
+	Finished  *time.Time `json:"finished,omitempty"`
+	Running   bool       `json:"running"`
+	Status    *int       `json:"status,omitempty"`
+	Error     string     `json:"error,omitempty"`
+	Output    string     `json:"output,omitempty"`
+	Truncated bool       `json:"truncated,omitempty"`
+	done      chan struct{}
+}
+
+type jobBook struct {
+	mu   sync.Mutex
+	seq  int
+	jobs map[string]*Job
+}
+
+var jobs = &jobBook{jobs: map[string]*Job{}}
+
+// startJob runs c in the background, held to JobLimit.
+func startJob(c Cmd) *Job {
+	c.Timeout = JobLimit
+	name, args := argv(c)
+	jobs.mu.Lock()
+	jobs.seq++
+	j := &Job{ID: fmt.Sprintf("%d-%d", time.Now().Unix(), jobs.seq), Command: strings.TrimSpace(name + " " + strings.Join(args, " ")),
+		Started: time.Now().UTC(), Running: true, done: make(chan struct{})}
+	jobs.jobs[j.ID] = j
+	jobs.forgetOldest()
+	jobs.mu.Unlock()
+	go func() {
+		r := run(c)
+		var err error
+		if r.Status != 0 || r.Error != "" {
+			err = failure(c, r)
+		}
+		jobs.mu.Lock()
+		now := time.Now().UTC()
+		j.Finished, j.Running = &now, false
+		status := r.Status
+		j.Status = &status
+		if err != nil {
+			j.Error = err.Error()
+		}
+		j.Output = tail(strings.TrimSpace(r.Stdout+"\n"+r.Stderr), 16<<10)
+		j.Truncated = r.Truncated || len(r.Stdout)+len(r.Stderr) > 16<<10
+		jobs.mu.Unlock()
+		close(j.done)
+	}()
+	return j
+}
+
+// forgetOldest keeps the book bounded; finished jobs go first. Called with the lock held.
+func (b *jobBook) forgetOldest() {
+	if len(b.jobs) <= keptJobs {
+		return
+	}
+	all := make([]*Job, 0, len(b.jobs))
+	for _, j := range b.jobs {
+		all = append(all, j)
+	}
+	sort.Slice(all, func(i, k int) bool { return all[i].Started.Before(all[k].Started) })
+	for _, j := range all {
+		if len(b.jobs) <= keptJobs {
+			return
+		}
+		if !j.Running {
+			delete(b.jobs, j.ID)
+		}
+	}
+}
+
+// awaitJob waits up to d for a job to finish and answers a copy of it as it then stands.
+func awaitJob(j *Job, d time.Duration) Job {
+	select {
+	case <-j.done:
+	case <-time.After(d):
+	}
+	return snapshot(j)
+}
+
+func snapshot(j *Job) Job {
+	jobs.mu.Lock()
+	defer jobs.mu.Unlock()
+	c := *j
+	c.done = nil
+	return c
+}
+
+// jobByID answers a job by its id, or says it is not known to this process.
+func jobByID(id string) (Job, error) {
+	jobs.mu.Lock()
+	j, ok := jobs.jobs[id]
+	jobs.mu.Unlock()
+	if !ok {
+		return Job{}, fmt.Errorf("no job %s in this process: it was never started here, was forgotten after %d newer ones, or the bundle has restarted since", id, keptJobs)
+	}
+	return snapshot(j), nil
+}
+
+// listJobs answers every job this process knows, newest first.
+func listJobs() []Job {
+	jobs.mu.Lock()
+	all := make([]*Job, 0, len(jobs.jobs))
+	for _, j := range jobs.jobs {
+		all = append(all, j)
+	}
+	jobs.mu.Unlock()
+	sort.Slice(all, func(i, k int) bool { return all[i].Started.After(all[k].Started) })
+	out := make([]Job, 0, len(all))
+	for _, j := range all {
+		out = append(out, snapshot(j))
+	}
+	return out
+}
+
+// actAsJob starts c and answers the job once it finishes or JobWait passes, whichever is first.
+// A finished job that failed is answered as an error, so a failed act is never read as success.
+func actAsJob(c Cmd) (Job, error) {
+	j := awaitJob(startJob(c), JobWait)
+	if !j.Running && j.Error != "" {
+		return j, fmt.Errorf("%s (job %s)", j.Error, j.ID)
+	}
+	return j, nil
+}

modules/docker-compose/cmd/docker-compose-tools/jobs_test.go

@@ -0,0 +1,51 @@
+package main
+
+import (
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestJobsAFastActIsAnsweredFinishedAndAFailedOneAsAnError(t *testing.T) {
+	using(t, func(line string, c Cmd) Result {
+		if c.Timeout != JobLimit {
+			t.Errorf("a job is held to JobLimit, not %s", c.Timeout)
+		}
+		if strings.Contains(line, "bad") {
+			return Result{Status: 2, Stderr: "it broke"}
+		}
+		return ok("done")
+	})
+	j, err := actAsJob(Cmd{Name: "good"})
+	if err != nil || j.Running || j.Status == nil || *j.Status != 0 || j.Output != "done" {
+		t.Fatalf("%+v %v", j, err)
+	}
+	if _, err := actAsJob(Cmd{Name: "bad"}); err == nil || !strings.Contains(err.Error(), "it broke") {
+		t.Fatalf("a failed job: %v", err)
+	}
+	got, err := jobByID(j.ID)
+	if err != nil || got.ID != j.ID {
+		t.Fatalf("by id: %+v %v", got, err)
+	}
+	if _, err := jobByID("nope"); err == nil {
+		t.Fatal("an unknown job")
+	}
+	if len(listJobs()) < 2 {
+		t.Fatal("listed")
+	}
+}
+
+func TestJobsASlowActIsAnsweredRunningWithItsID(t *testing.T) {
+	release := make(chan struct{})
+	using(t, func(line string, c Cmd) Result { <-release; return ok("") })
+	j := awaitJob(startJob(Cmd{Name: "slow"}), 50*time.Millisecond)
+	if !j.Running || j.ID == "" {
+		t.Fatalf("%+v", j)
+	}
+	close(release)
+	time.Sleep(50 * time.Millisecond)
+	got, _ := jobByID(j.ID)
+	if got.Running {
+		t.Fatalf("finished afterwards: %+v", got)
+	}
+}

modules/docker-compose/cmd/docker-compose-tools/kit.go

@@ -0,0 +1,352 @@
+package main
+
+// kit.go is the same file in each of the workstations' tool bundles (fonts, docker-compose, snapd,
+// flatpak, cups, bluetooth, xclip, dmenu): how a tool runs a command, escalates, bounds what it
+// keeps, and names a failure. A module is built from its own directory, so the file is copied rather
+// than shared; a change to one copy is made to all eight.
+//
+// The rules it holds (novox/hq research 026/05, to-be 38 WP4):
+//   - the node's tool runtime runs as the operator account, not root (ADR 0175 §4); a command that
+//     needs root goes through `sudo -n`, never a prompt, and a refusal is named as such;
+//   - one command gets 20 s, below the runtime's 30 s call limit, and is ended with everything it
+//     started when it takes longer;
+//   - each stream is kept to 256 KiB, and the answer says when it was cut;
+//   - a failure is an error with what went wrong in it, never an empty answer.
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"strings"
+	"syscall"
+	"time"
+)
+
+// Bounds every command is held to.
+const (
+	CallTimeout = 20 * time.Second
+	MostOutput  = 256 << 10
+)
+
+// Cmd is one command a tool runs.
+type Cmd struct {
+	Name string
+	Args []string
+	// Stdin is written to the command's standard input when not empty.
+	Stdin string
+	// Env is added to this process's own environment.
+	Env []string
+	// Root says the command needs root: it is run through `sudo -n` when this process is not root.
+	Root bool
+	// Timeout replaces CallTimeout; only a background job (jobs.go) asks for longer.
+	Timeout time.Duration
+	// Detached is for a program that forks a child which outlives it, as xclip does to keep the
+	// selection: its streams go to files, because a pipe the child inherits would hold the call open
+	// until the child exits.
+	Detached bool
+}
+
+// Result is what a command did.
+type Result struct {
+	Stdout string `json:"stdout"`
+	Stderr string `json:"stderr"`
+	Status int    `json:"status"`
+	// Error is why it did not run to an answer: "not-found" when the program is not there,
+	// "timeout" when it was ended for taking too long, else the spawn error.
+	Error     string `json:"error,omitempty"`
+	Truncated bool   `json:"truncated,omitempty"`
+}
+
+// Runner runs a command. Tests replace it; nothing else does.
+type Runner func(Cmd) Result
+
+var (
+	run  Runner = execRun
+	euid        = os.Geteuid
+)
+
+// argv is the command as it is run: through sudo without a prompt when it needs root and this
+// process is not root.
+func argv(c Cmd) (string, []string) {
+	if c.Root && euid() != 0 {
+		return "sudo", append([]string{"-n", c.Name}, c.Args...)
+	}
+	return c.Name, c.Args
+}
+
+// bounded keeps the first MostOutput bytes written to it and notes that more came.
+type bounded struct {
+	b   bytes.Buffer
+	cut bool
+}
+
+func (w *bounded) Write(p []byte) (int, error) {
+	room := MostOutput - w.b.Len()
+	if room <= 0 {
+		w.cut = w.cut || len(p) > 0
+		return len(p), nil
+	}
+	if len(p) > room {
+		w.b.Write(p[:room])
+		w.cut = true
+		return len(p), nil
+	}
+	return w.b.Write(p)
+}
+
+func execRun(c Cmd) Result {
+	timeout := c.Timeout
+	if timeout <= 0 {
+		timeout = CallTimeout
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), timeout)
+	defer cancel()
+	name, args := argv(c)
+	cmd := exec.CommandContext(ctx, name, args...)
+	cmd.Env = append(append(os.Environ(), "LC_ALL=C"), c.Env...)
+	if !c.Detached {
+		// Its own process group, so that ending it on a timeout ends what it started too.
+		cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+		cmd.Cancel = func() error {
+			if cmd.Process != nil {
+				_ = syscall.Kill(-cmd.Process.Pid, syscall.SIGKILL)
+			}
+			return nil
+		}
+	}
+	cmd.WaitDelay = 2 * time.Second
+	if c.Stdin != "" {
+		cmd.Stdin = strings.NewReader(c.Stdin)
+	}
+	var out, errs bounded
+	var outFile, errFile *os.File
+	if c.Detached {
+		var err error
+		if outFile, err = os.CreateTemp("", "mesh-tool-out-*"); err != nil {
+			return Result{Status: 127, Error: err.Error()}
+		}
+		defer os.Remove(outFile.Name())
+		defer outFile.Close()
+		if errFile, err = os.CreateTemp("", "mesh-tool-err-*"); err != nil {
+			return Result{Status: 127, Error: err.Error()}
+		}
+		defer os.Remove(errFile.Name())
+		defer errFile.Close()
+		cmd.Stdout, cmd.Stderr = outFile, errFile
+	} else {
+		cmd.Stdout, cmd.Stderr = &out, &errs
+	}
+	err := cmd.Run()
+	if c.Detached {
+		for _, f := range []struct {
+			file *os.File
+			into *bounded
+		}{{outFile, &out}, {errFile, &errs}} {
+			if _, e := f.file.Seek(0, io.SeekStart); e == nil {
+				_, _ = io.Copy(f.into, f.file)
+			}
+		}
+	}
+	r := Result{Stdout: out.b.String(), Stderr: errs.b.String(), Truncated: out.cut || errs.cut}
+	var exit *exec.ExitError
+	switch {
+	case err == nil:
+	case ctx.Err() == context.DeadlineExceeded:
+		r.Status, r.Error = 124, "timeout"
+	case errors.Is(err, exec.ErrNotFound) || errors.Is(err, os.ErrNotExist):
+		r.Status, r.Error = 127, "not-found"
+	case errors.As(err, &exit):
+		r.Status = exit.ExitCode()
+	default:
+		r.Status, r.Error = 127, err.Error()
+	}
+	return r
+}
+
+// call runs a command and answers its result, or an error naming what went wrong.
+func call(c Cmd) (Result, error) {
+	r := run(c)
+	if r.Status == 0 && r.Error == "" {
+		return r, nil
+	}
+	return r, failure(c, r)
+}
+
+// failure names how a command failed: not installed, refused escalation, too slow, or its exit
+// status with the end of what it said.
+func failure(c Cmd, r Result) error {
+	program, _ := argv(c)
+	switch {
+	case r.Error == "not-found" && program == "sudo":
+		return fmt.Errorf("%s needs root, and sudo is not installed here for the runtime's account to escalate with", c.Name)
+	case r.Error == "not-found":
+		if hint, ok := providedBy[c.Name]; ok {
+			return fmt.Errorf("%s is not installed on this machine (%s)", c.Name, hint)
+		}
+		return fmt.Errorf("%s is not installed on this machine", c.Name)
+	case r.Error == "timeout":
+		limit := c.Timeout
+		if limit <= 0 {
+			limit = CallTimeout
+		}
+		return fmt.Errorf("%s gave no answer within %s and was ended", c.Name, limit)
+	case r.Error != "":
+		return fmt.Errorf("%s did not run: %s", c.Name, r.Error)
+	case program == "sudo" && strings.Contains(r.Stderr, "command not found"):
+		if hint, ok := providedBy[c.Name]; ok {
+			return fmt.Errorf("%s is not installed on this machine (%s)", c.Name, hint)
+		}
+		return fmt.Errorf("%s is not installed on this machine", c.Name)
+	case program == "sudo" && strings.HasPrefix(strings.TrimSpace(r.Stderr), "sudo:"):
+		return fmt.Errorf("%s needs root, and sudo -n refused the runtime's account: %s (the escalation is the sudo module's to declare)",
+			c.Name, firstLine(r.Stderr))
+	}
+	said := tail(strings.TrimSpace(r.Stderr), 2000)
+	if said == "" {
+		said = tail(strings.TrimSpace(r.Stdout), 2000)
+	}
+	if said == "" {
+		said = "and said nothing"
+	}
+	return fmt.Errorf("%s %s exited %d: %s", c.Name, strings.Join(c.Args, " "), r.Status, said)
+}
+
+func firstLine(s string) string {
+	s = strings.TrimSpace(s)
+	if i := strings.IndexByte(s, '\n'); i >= 0 {
+		return s[:i]
+	}
+	return s
+}
+
+func tail(s string, n int) string {
+	if len(s) <= n {
+		return s
+	}
+	return "…" + s[len(s)-n:]
+}
+
+// lines are a command's output lines, blank ones dropped.
+func lines(s string) []string {
+	out := []string{}
+	for _, l := range strings.Split(s, "\n") {
+		if strings.TrimSpace(l) != "" {
+			out = append(out, strings.TrimRight(l, "\r"))
+		}
+	}
+	return out
+}
+
+// Arguments, read the way a tool's JSON arguments arrive.
+
+func text(args map[string]any, key string) (string, error) {
+	v, ok := args[key]
+	if !ok || v == nil {
+		return "", fmt.Errorf("%s is required", key)
+	}
+	s, ok := v.(string)
+	if !ok {
+		return "", fmt.Errorf("%s must be a string", key)
+	}
+	if strings.TrimSpace(s) == "" {
+		return "", fmt.Errorf("%s must not be empty", key)
+	}
+	return s, nil
+}
+
+func optText(args map[string]any, key, def string) (string, error) {
+	v, ok := args[key]
+	if !ok || v == nil {
+		return def, nil
+	}
+	s, ok := v.(string)
+	if !ok {
+		return "", fmt.Errorf("%s must be a string", key)
+	}
+	if strings.TrimSpace(s) == "" {
+		return def, nil
+	}
+	return s, nil
+}
+
+// optWhole reads a whole number, defaulted, refused below least and held to most.
+func optWhole(args map[string]any, key string, def, least, most int) (int, error) {
+	v, ok := args[key]
+	if !ok || v == nil {
+		return def, nil
+	}
+	f, ok := v.(float64)
+	if !ok {
+		if i, isInt := v.(int); isInt {
+			f = float64(i)
+		} else {
+			return 0, fmt.Errorf("%s must be a number", key)
+		}
+	}
+	if f != float64(int(f)) {
+		return 0, fmt.Errorf("%s must be a whole number", key)
+	}
+	n := int(f)
+	if n < least {
+		return 0, fmt.Errorf("%s must be at least %d", key, least)
+	}
+	if n > most {
+		n = most
+	}
+	return n, nil
+}
+
+func optFlag(args map[string]any, key string, def bool) (bool, error) {
+	v, ok := args[key]
+	if !ok || v == nil {
+		return def, nil
+	}
+	b, ok := v.(bool)
+	if !ok {
+		return false, fmt.Errorf("%s must be true or false", key)
+	}
+	return b, nil
+}
+
+func optList(args map[string]any, key string) ([]string, error) {
+	v, ok := args[key]
+	if !ok || v == nil {
+		return nil, nil
+	}
+	items, ok := v.([]any)
+	if !ok {
+		return nil, fmt.Errorf("%s must be a list of strings", key)
+	}
+	out := make([]string, 0, len(items))
+	for _, it := range items {
+		s, ok := it.(string)
+		if !ok || strings.TrimSpace(s) == "" {
+			return nil, fmt.Errorf("%s must be a list of non-empty strings", key)
+		}
+		out = append(out, s)
+	}
+	return out, nil
+}
+
+// oneOf refuses a value outside a closed set.
+func oneOf(key, value string, allowed ...string) error {
+	for _, a := range allowed {
+		if value == a {
+			return nil
+		}
+	}
+	return fmt.Errorf("%s must be one of %s, not %q", key, strings.Join(allowed, ", "), value)
+}
+
+// plainName refuses a name that could be read as an option or carries a path or a space: package,
+// snap, application and printer names never do.
+func plainName(key, value string) error {
+	if strings.HasPrefix(value, "-") || strings.ContainsAny(value, " \t\n/\\") {
+		return fmt.Errorf("%s %q is not a plain name", key, value)
+	}
+	return nil
+}

modules/docker-compose/cmd/docker-compose-tools/kit_test.go

@@ -0,0 +1,147 @@
+package main
+
+// Tests of kit.go, the same in each workstation module.
+
+import (
+	"strings"
+	"testing"
+	"time"
+)
+
+// fake records the commands asked and answers each from a function of the command line.
+type fake struct {
+	asked  []Cmd
+	answer func(line string, c Cmd) Result
+}
+
+func (f *fake) runner() Runner {
+	return func(c Cmd) Result {
+		f.asked = append(f.asked, c)
+		name, args := argv(c)
+		line := strings.TrimSpace(name + " " + strings.Join(args, " "))
+		if f.answer == nil {
+			return Result{}
+		}
+		return f.answer(line, c)
+	}
+}
+
+func (f *fake) lines() []string {
+	out := []string{}
+	for _, c := range f.asked {
+		name, args := argv(c)
+		out = append(out, strings.TrimSpace(name+" "+strings.Join(args, " ")))
+	}
+	return out
+}
+
+// using installs a fake runner and a non-root uid for one test.
+func using(t *testing.T, answer func(line string, c Cmd) Result) *fake {
+	t.Helper()
+	f := &fake{answer: answer}
+	wasRun, wasUID := run, euid
+	run, euid = f.runner(), func() int { return 1000 }
+	t.Cleanup(func() { run, euid = wasRun, wasUID })
+	return f
+}
+
+func ok(stdout string) Result { return Result{Stdout: stdout} }
+
+func TestKitAnActThatNeedsRootGoesThroughSudoWithoutAPromptUnlessAlreadyRoot(t *testing.T) {
+	was := euid
+	defer func() { euid = was }()
+	euid = func() int { return 1000 }
+	if name, args := argv(Cmd{Name: "x", Args: []string{"a"}, Root: true}); name != "sudo" || strings.Join(args, " ") != "-n x a" {
+		t.Fatalf("not root: %s %v", name, args)
+	}
+	if name, _ := argv(Cmd{Name: "x"}); name != "x" {
+		t.Fatalf("a read is run as the account: %s", name)
+	}
+	euid = func() int { return 0 }
+	if name, _ := argv(Cmd{Name: "x", Root: true}); name != "x" {
+		t.Fatalf("as root no sudo: %s", name)
+	}
+}
+
+func TestKitAFailureIsNamedByHowItFailed(t *testing.T) {
+	was := euid
+	defer func() { euid = was }()
+	euid = func() int { return 1000 }
+	cases := []struct {
+		c    Cmd
+		r    Result
+		want string
+	}{
+		{Cmd{Name: "nothere"}, Result{Status: 127, Error: "not-found"}, "not installed"},
+		{Cmd{Name: "x", Root: true}, Result{Status: 127, Error: "not-found"}, "sudo is not installed"},
+		{Cmd{Name: "x", Root: true}, Result{Status: 1, Stderr: "sudo: a password is required\n"}, "sudo -n refused"},
+		{Cmd{Name: "x", Root: true}, Result{Status: 1, Stderr: "sudo: x: command not found\n"}, "x is not installed"},
+		{Cmd{Name: "x"}, Result{Status: 124, Error: "timeout"}, "within 20s"},
+		{Cmd{Name: "x", Args: []string{"y"}}, Result{Status: 3, Stderr: "boom\n"}, "x y exited 3: boom"},
+		{Cmd{Name: "x"}, Result{Status: 3}, "said nothing"},
+	}
+	for _, k := range cases {
+		err := failure(k.c, k.r)
+		if err == nil || !strings.Contains(err.Error(), k.want) {
+			t.Errorf("%+v: %v, want %q", k.r, err, k.want)
+		}
+	}
+}
+
+func TestKitOutputIsBoundedAndSaysSo(t *testing.T) {
+	var w bounded
+	big := strings.Repeat("a", MostOutput+10)
+	n, _ := w.Write([]byte(big))
+	if n != len(big) || w.b.Len() != MostOutput || !w.cut {
+		t.Fatalf("kept %d of %d, cut %v", w.b.Len(), len(big), w.cut)
+	}
+}
+
+func TestKitTheRealRunnerRunsEndsAndReportsAMissingProgram(t *testing.T) {
+	r := execRun(Cmd{Name: "sh", Args: []string{"-c", "echo out; echo err >&2; exit 3"}})
+	if r.Status != 3 || strings.TrimSpace(r.Stdout) != "out" || strings.TrimSpace(r.Stderr) != "err" {
+		t.Fatalf("%+v", r)
+	}
+	r = execRun(Cmd{Name: "sh", Args: []string{"-c", "sleep 5 & sleep 5"}, Timeout: 200 * time.Millisecond})
+	if r.Error != "timeout" {
+		t.Fatalf("a slow command: %+v", r)
+	}
+	r = execRun(Cmd{Name: "no-such-program-anywhere"})
+	if r.Error != "not-found" {
+		t.Fatalf("a missing program: %+v", r)
+	}
+	r = execRun(Cmd{Name: "cat", Stdin: "given"})
+	if r.Stdout != "given" {
+		t.Fatalf("stdin: %+v", r)
+	}
+	start := time.Now()
+	r = execRun(Cmd{Name: "sh", Args: []string{"-c", "echo kept; (sleep 3 &) ; exit 0"}, Detached: true})
+	if r.Status != 0 || strings.TrimSpace(r.Stdout) != "kept" || time.Since(start) > 2*time.Second {
+		t.Fatalf("a detached command returns when it exits, not when its child does: %+v after %s", r, time.Since(start))
+	}
+}
+
+func TestKitArgumentsAreReadStrictly(t *testing.T) {
+	args := map[string]any{"s": "x", "n": float64(5), "f": 1.5, "b": true, "l": []any{"a", "b"}}
+	if _, err := text(args, "missing"); err == nil {
+		t.Error("a missing required string")
+	}
+	if n, _ := optWhole(args, "n", 1, 1, 3); n != 3 {
+		t.Errorf("held to most: %d", n)
+	}
+	if _, err := optWhole(args, "n", 1, 6, 9); err == nil {
+		t.Error("below least")
+	}
+	if _, err := optWhole(args, "f", 1, 0, 9); err == nil {
+		t.Error("a fraction")
+	}
+	if l, _ := optList(args, "l"); len(l) != 2 {
+		t.Errorf("list: %v", l)
+	}
+	if b, _ := optFlag(args, "b", false); !b {
+		t.Error("flag")
+	}
+	if err := plainName("name", "--all"); err == nil {
+		t.Error("an option as a name")
+	}
+}

modules/docker-compose/cmd/docker-compose-tools/main.go

@@ -0,0 +1,199 @@
+// The docker-compose module's tools (novox/hq research 027/02, 026/05): the compose projects on this
+// machine, their containers, logs and rendered configuration, and bringing one up, down or round
+// again by its directory. A Go bundle the node's runtime launches over stdio (ADR 0188, ADR 0193); it
+// runs as the operator account, which reaches the container runtime through the docker group.
+package main
+
+import (
+	"fmt"
+	"os"
+
+	stdio "git.novox.be/novox/mesh-sdk/go"
+)
+
+var providedBy = map[string]string{
+	"docker": "the docker module installs the container runtime; this module adds compose to it",
+}
+
+func main() {
+	if err := stdio.Serve("", tools()); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
+
+// where is the argument schema every tool that acts on one project takes.
+var where = map[string]any{
+	"dir":     map[string]any{"type": "string", "description": "the project's directory, absolute: where its compose file is"},
+	"project": map[string]any{"type": "string", "description": "the project's name, for a project docker already knows (instead of dir)"},
+}
+
+func with(extra map[string]any) map[string]any {
+	out := map[string]any{}
+	for k, v := range where {
+		out[k] = v
+	}
+	for k, v := range extra {
+		out[k] = v
+	}
+	return out
+}
+
+var servicesArg = map[string]any{"type": "array", "items": map[string]any{"type": "string"}, "description": "only these services (default all)"}
+
+func tools() []stdio.Tool {
+	return []stdio.Tool{
+		{
+			Name: "docker_compose_projects",
+			Description: "The compose projects docker knows on this machine, running or stopped: name, status, working " +
+				"directory, compose files, services, and containers running of total. (r)",
+			Input: map[string]any{},
+			Run:   func(map[string]any) (any, error) { return Projects() },
+		},
+		{
+			Name:        "docker_compose_ps",
+			Description: "One project's containers: service, state, health, exit code, image and published ports. (r)",
+			Input:       with(nil),
+			Run: func(args map[string]any) (any, error) {
+				t, err := targetOf(args, false)
+				if err != nil {
+					return nil, err
+				}
+				return Ps(t)
+			},
+		},
+		{
+			Name: "docker_compose_logs",
+			Description: "One project's logs, the last lines of each service (default 200, at most 5000), optionally since a " +
+				"time (\"10m\", \"2026-10-04T12:00:00\"). Cut at 256 KiB. (r)",
+			Input: with(map[string]any{
+				"services": servicesArg,
+				"tail":     map[string]any{"type": "integer", "description": "lines per service (default 200, at most 5000)"},
+				"since":    map[string]any{"type": "string", "description": "only lines since this: a duration such as 10m or a timestamp"},
+			}),
+			Run: func(args map[string]any) (any, error) {
+				t, err := targetOf(args, false)
+				if err != nil {
+					return nil, err
+				}
+				services, err := optList(args, "services")
+				if err != nil {
+					return nil, err
+				}
+				n, err := optWhole(args, "tail", 200, 1, 5000)
+				if err != nil {
+					return nil, err
+				}
+				since, err := optText(args, "since", "")
+				if err != nil {
+					return nil, err
+				}
+				return Logs(t, services, n, since)
+			},
+		},
+		{
+			Name: "docker_compose_config",
+			Description: "A project's configuration as compose renders it: files merged, variables filled. Values of " +
+				"environment variables, build arguments and labels whose names suggest a secret are replaced with " +
+				"[redacted]. An invalid file is answered as the error compose gives. (r)",
+			Input: with(nil),
+			Run: func(args map[string]any) (any, error) {
+				t, err := targetOf(args, true)
+				if err != nil {
+					return nil, err
+				}
+				return Config(t)
+			},
+		},
+		{
+			Name: "docker_compose_up",
+			Description: "Bring a project up, detached: create and start its containers, building or pulling what is " +
+				"missing. Answers when finished, or after 18 s with a job to follow with docker_compose_job. (a)",
+			Input: with(map[string]any{
+				"services": servicesArg,
+				"build":    map[string]any{"type": "boolean", "description": "build images before starting (--build)"},
+				"pull":     map[string]any{"type": "string", "enum": []string{"missing", "always", "never"}, "description": "pull policy (default missing)"},
+			}),
+			Run: func(args map[string]any) (any, error) {
+				t, err := targetOf(args, true)
+				if err != nil {
+					return nil, err
+				}
+				services, err := optList(args, "services")
+				if err != nil {
+					return nil, err
+				}
+				build, err := optFlag(args, "build", false)
+				if err != nil {
+					return nil, err
+				}
+				pull, err := optText(args, "pull", "missing")
+				if err != nil {
+					return nil, err
+				}
+				return Up(t, services, build, pull)
+			},
+		},
+		{
+			Name: "docker_compose_down",
+			Description: "Stop and remove a project's containers and networks. Its volumes are kept: removing data is not " +
+				"this tool's. Answers when finished, or with a job to follow. (a)",
+			Input: with(nil),
+			Run: func(args map[string]any) (any, error) {
+				t, err := targetOf(args, false)
+				if err != nil {
+					return nil, err
+				}
+				return Down(t)
+			},
+		},
+		{
+			Name:        "docker_compose_restart",
+			Description: "Restart a project's containers, or some of its services. Answers when finished, or with a job to follow. (a)",
+			Input:       with(map[string]any{"services": servicesArg}),
+			Run: func(args map[string]any) (any, error) {
+				t, err := targetOf(args, false)
+				if err != nil {
+					return nil, err
+				}
+				services, err := optList(args, "services")
+				if err != nil {
+					return nil, err
+				}
+				return Restart(t, services)
+			},
+		},
+		{
+			Name:        "docker_compose_pull",
+			Description: "Pull a project's images, or some services', without starting anything. Answers when finished, or with a job to follow. (a)",
+			Input:       with(map[string]any{"services": servicesArg}),
+			Run: func(args map[string]any) (any, error) {
+				t, err := targetOf(args, true)
+				if err != nil {
+					return nil, err
+				}
+				services, err := optList(args, "services")
+				if err != nil {
+					return nil, err
+				}
+				return Pull(t, services)
+			},
+		},
+		{
+			Name: "docker_compose_job",
+			Description: "A long act this module started (up, down, restart, pull): running or finished, its exit status " +
+				"and the end of its output. Without job, every act this process knows, newest first. (r)",
+			Input: map[string]any{"job": map[string]any{"type": "string", "description": "the job id an act answered"}},
+			Run: func(args map[string]any) (any, error) {
+				id, err := optText(args, "job", "")
+				if err != nil {
+					return nil, err
+				}
+				if id == "" {
+					return map[string]any{"jobs": listJobs()}, nil
+				}
+				return jobByID(id)
+			},
+		},
+	}
+}

modules/docker-compose/cmd/docker-compose-tools/manifest_kit_test.go

@@ -0,0 +1,107 @@
+package main
+
+// manifest_kit_test.go is the same file in each workstation module: it reads the module's
+// definition so the module's own tests can hold it to what it says.
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"testing"
+)
+
+type manifest struct {
+	Module       string           `json:"module"`
+	Capabilities []string         `json:"capabilities"`
+	Claims       []any            `json:"claims"`
+	Seats        []any            `json:"seats"`
+	Tools        []string         `json:"tools"`
+	Resources    []map[string]any `json:"resources"`
+	Build        struct {
+		Artifacts []map[string]any `json:"artifacts"`
+	} `json:"build"`
+}
+
+func readManifest(t *testing.T) manifest {
+	t.Helper()
+	raw, err := os.ReadFile(filepath.Join("..", "..", "module.json"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	var m manifest
+	if err := json.Unmarshal(raw, &m); err != nil {
+		t.Fatalf("module.json: %v", err)
+	}
+	return m
+}
+
+func (m manifest) resource(id string) map[string]any {
+	for _, r := range m.Resources {
+		if r["id"] == id {
+			return r
+		}
+	}
+	return nil
+}
+
+// packages are the packages the module installs, sorted.
+func (m manifest) packages() []string {
+	out := []string{}
+	for _, r := range m.Resources {
+		if r["type"] == "package" && r["absent"] != true {
+			out = append(out, r["package"].(string))
+		}
+	}
+	sort.Strings(out)
+	return out
+}
+
+// services are the units the module declares, by unit name.
+func (m manifest) services() map[string]map[string]any {
+	out := map[string]map[string]any{}
+	for _, r := range m.Resources {
+		if r["type"] == "service" {
+			out[r["unit"].(string)] = r
+		}
+	}
+	return out
+}
+
+// holdsTheBundle holds the manifest to the Go bundle this directory builds: every tool registered
+// is listed and nothing else, each named <prefix>_…, and the artifact builds this command.
+func holdsTheBundle(t *testing.T, m manifest, prefix string) {
+	t.Helper()
+	registered := []string{}
+	for _, tool := range tools() {
+		registered = append(registered, tool.Name)
+		if !strings.HasPrefix(tool.Name, prefix+"_") {
+			t.Errorf("tool %s is not named %s_…", tool.Name, prefix)
+		}
+		if tool.Description == "" || tool.Run == nil || tool.Input == nil {
+			t.Errorf("tool %s is not described, runnable and given an input schema", tool.Name)
+		}
+	}
+	if strings.Join(registered, ",") != strings.Join(m.Tools, ",") {
+		t.Errorf("registered %v, listed %v", registered, m.Tools)
+	}
+	if len(m.Build.Artifacts) != 1 {
+		t.Fatalf("one artifact, got %d", len(m.Build.Artifacts))
+	}
+	cwd, _ := os.Getwd()
+	binary := filepath.Base(cwd)
+	a := m.Build.Artifacts[0]
+	want := map[string]any{"kind": "bundle", "language": "go", "system": "arch", "from": "cmd/" + binary, "binary": binary}
+	for k, v := range want {
+		if a[k] != v {
+			t.Errorf("artifact %s = %v, want %v", k, a[k], v)
+		}
+	}
+	if loads, _ := a["loads"].([]any); len(loads) != 1 || loads[0] != binary {
+		t.Errorf("artifact loads %v, want [%s]", a["loads"], binary)
+	}
+	if m.Claims != nil || m.Seats != nil {
+		t.Errorf("claims %v, seats %v: this module holds no seat", m.Claims, m.Seats)
+	}
+}

modules/docker-compose/go.mod

@@ -0,0 +1,5 @@
+module docker-compose
+
+go 1.22
+
+require git.novox.be/novox/mesh-sdk/go v0.1.6

modules/docker-compose/go.sum

@@ -0,0 +1,2 @@
+git.novox.be/novox/mesh-sdk/go v0.1.6 h1:9qzdYONYbJdWcu6sxQcq9v1LI0JxcfkiKYkMUzJSkVQ=
+git.novox.be/novox/mesh-sdk/go v0.1.6/go.mod h1:GFuZUElBZ9A++mxgIKo97aXXo+kV0uJ/UkbhQPPIbrY=

modules/docker-compose/module.json

@@ -0,0 +1,40 @@
+{
+  "module": "docker-compose",
+  "version": "1",
+  "capabilities": [
+    "package-manager"
+  ],
+  "tools": [
+    "docker_compose_projects",
+    "docker_compose_ps",
+    "docker_compose_logs",
+    "docker_compose_config",
+    "docker_compose_up",
+    "docker_compose_down",
+    "docker_compose_restart",
+    "docker_compose_pull",
+    "docker_compose_job"
+  ],
+  "resources": [
+    {
+      "id": "package",
+      "type": "package",
+      "package": "docker-compose"
+    }
+  ],
+  "build": {
+    "artifacts": [
+      {
+        "name": "tools",
+        "kind": "bundle",
+        "language": "go",
+        "system": "arch",
+        "from": "cmd/docker-compose-tools",
+        "binary": "docker-compose-tools",
+        "loads": [
+          "docker-compose-tools"
+        ]
+      }
+    ]
+  }
+}

modules/docker/README.md

@@ -0,0 +1,166 @@
+# docker
+
+The container runtime as a module (novox/hq to-be 42 phase 1, item 8; research 027/01–02; ADR 0166,
+ADR 0207). It claims the node seat `node-container-runtime`. That seat carries no verbs yet: its verbs,
+and the host creating containers through its holder, wait on ADR 0166's acceptance. Until then the
+tools below are the module's own.
+
+## What it declares
+
+| resource | what | the host's rule |
+|---|---|---|
+| `package` | `docker` | installed if absent; never uninstalled when the module goes |
+| `buildx` | `docker-buildx` | the same. Only the build machine has it today; `docker build` needs it for BuildKit everywhere |
+| `socket` | `docker.socket` running, enabled at boot | given back as found when the module goes (ADR 0118) |
+| `prune-service`, `prune-timer` | `/etc/systemd/system/docker-prune.{service,timer}`, written whole | removed with the module |
+| `prune` | `docker-prune.timer` running, enabled at boot; restarted when either file changes | stopped and disabled with the module (the mesh made the unit) |
+
+The weekly prune takes **dangling images and build cache unused for a week, and nothing else**. It
+takes no volume, no container and no image a container uses, so it never touches a container the mesh
+holds. It runs at idle priority, at a random point in the hour after the weekly mark. A run missed
+while the machine was off happens at the next boot.
+
+**Capabilities:** `package-manager`, `service-manager`, `privileged`. It does not declare
+`container-runtime`: under ADR 0165, which is still proposed, that word means a running daemon, and
+the module that installs the daemon cannot require it.
+
+## What it does not declare yet, and why
+
+Three things this module should own are already declared by other modules on every machine. The
+controller refuses two modules on one node that declare the same `path`, `unit`, `name` or `package`
+(`checkResources`, mesh-controller `internal/catalogue/resolve.go`). Declaring any of them here would
+make the module unassignable everywhere. The refusals were checked against the controller's own
+check:
+
+```
+zsh and docker both declare the name "${machine:account}"
+dnsmasq and docker both declare the path "/etc/docker/daemon.json"
+dnsmasq and docker both declare the unit "docker.service"
+```
+
+### 1. `/etc/docker/daemon.json` and `docker.service` (issue 190)
+
+Today the file has three writers. Each writes into it (`into: json`, ADR 0102) and reloads the
+service:
+
+- **`dnsmasq`** writes `dns` and `live-restore`, through `dnsmasq.runtime-dns` and `dnsmasq.runtime`.
+- **The private network**, generated by the controller (`internal/overlay/generator.go`), writes
+  `insecure-registries`. The collision check does not see generated resources.
+- **Nobody** writes log rotation. One machine has `log-driver` and `log-opts` by hand.
+
+**The change proposed, in one merge:**
+
+1. `dnsmasq` drops its `runtime-dns` and `runtime` resources.
+2. `docker` adds the two resources below:
+
+   ```json
+   {"id": "daemon", "type": "file", "path": "/etc/docker/daemon.json", "mode": "0644", "into": "json",
+    "content": "{\"dns\": [\"${machine:address}\"], \"live-restore\": true, \"log-driver\": \"json-file\", \"log-opts\": {\"max-size\": \"100m\", \"max-file\": \"5\"}}\n"},
+   {"id": "runtime", "type": "service", "unit": "docker.service", "state": "running", "boot": "enabled", "reload-on": ["daemon"]}
+   ```
+
+   The service is **reloaded, never restarted**: a restart stops every container. The daemon reads
+   `live-restore` on a reload. It reads `dns`, `log-driver` and `log-opts` only at its next start, so
+   they apply then (to containers created afterwards, for the log keys). With `live-restore` on, that
+   start keeps every container running.
+
+**Why one merge, and only after this module is on every machine:**
+
+- In one apply, the host first gives back the resources that are no longer declared, then applies
+  the new ones (mesh-host `apply.go`).
+- `dnsmasq` gives back `dns` and `live-restore` to what they held before it, and `docker` sets them
+  again in the same apply. The daemon is reloaded once, after both steps.
+- A machine pushed the new `dnsmasq` *without* this module would keep its pre-mesh values for both
+  keys. On one machine that is `live-restore: false`, and the next daemon restart there would stop
+  every container.
+
+**Later:** the controller hands the registry to this module as a value, and the overlay stops
+generating its two resources (issue 190, steps 2 and 5). Until then the overlay keeps writing its one
+key beside this module's. The host merges disjoint keys correctly; the mesh-host `into.go` record is
+per resource.
+
+### 2. The operator account's membership of the `docker` group
+
+The right shape is the host's `user` shape. Its `groups` are additive: the host runs
+`usermod --append` and never takes a group away.
+
+```json
+{"id": "group", "type": "user", "name": "${machine:account}", "groups": ["docker"]}
+```
+
+`zsh` already declares a `user` resource for the same account (its login shell). The controller
+compares `name` across modules, so the two collide.
+
+**The change proposed (mesh-controller, `checkResources`):** judge a `user` resource by the fields it
+sets, not by its name:
+
+- `shell` and `home` stay single-owner;
+- `groups` may be declared by any number of modules, because the host only adds them.
+
+Then this module declares the resource above, and no module has to carry another's group.
+
+Today the operator account is in the group on every machine, by hand. Nothing is lost while it waits.
+
+## The bootstrap's runtime
+
+On the machine the mesh was first installed on, the foundation bundle declared `package docker`
+(`container-runtime`) and `docker.service` running and enabled (`container-runtime-running`). ADR 0207
+§5 exempts them.
+
+- The host records them under their bare ids, with origin *carried*. A mesh declaration's orphan pass
+  never sees them (mesh-host `store.go`).
+- So `docker.package` here is a **second record of the same package**. The apply says "already
+  installed", and neither record ever uninstalls it.
+- This module does not declare `docker.service` today, so nothing overlaps there. The proposed step
+  1 would add a second record of that unit. Its found state is *running*, because genesis started
+  it, so undeclaring this module would leave the daemon running.
+
+## Tools
+
+The tools run as the operator account. If the daemon's socket refuses that account, a call is asked
+again through `sudo -n` (a process keeps the groups it started with). Every call has a 20 s bound.
+A failure is an error naming how it failed, never an empty answer.
+
+**Every container on the machine is in scope.** A container the mesh holds carries the host's label
+`mesh-host.id` (its value names the assignment), and every answer says `mesh_held`.
+
+| tool | | what |
+|---|---|---|
+| `docker_list` | r | every container: image, state, health, restarts, ports, mounts, compose project, `mesh_held`; filter by owner, state or name |
+| `docker_inspect` | r | one container whole, **environment values left out** (names kept) |
+| `docker_logs` | r | the last lines of both streams, merged in order, with timestamps (default 200, at most 2000) |
+| `docker_stats` | r | CPU, memory, I/O and process count per running container, heaviest first |
+| `docker_start` / `docker_stop` / `docker_restart` | a | one container. On a mesh-held one, the answer says the host restores its declared state at its next apply |
+| `docker_top` | r | the processes inside one container |
+| `docker_images` | r | images, largest first, with the containers using each; `dangling`, `unused` or `used` |
+| `docker_prune` | a | dangling images and build cache, and stopped containers the mesh does not hold if `containers` is true. **A dry run unless `dry_run` is false. Never a volume** |
+| `docker_disk_usage` | r | `docker system df -v`: total, active and reclaimable per kind, with the largest of each |
+| `docker_networks` | r | networks, subnets, and the containers on each |
+| `docker_volumes` | r | volumes, who mounts each, whether the mesh holds one of them, anonymous or not, and sizes if asked |
+| `docker_events` | r | the runtime's events over a window ending now (default 60 min, at most 24 h), without exec noise |
+| `docker_daemon_config` | r | `daemon.json` as on disk, `docker info`'s essentials, and keys the daemon has not taken yet |
+| `docker_unlabelled` | r | the containers the mesh does not hold: the cleanup list |
+| `docker_problems` | r | unhealthy, restarting, dead, killed for memory, failed, or restarted five times or more |
+| `docker_ports` | r | every published port, and the containers on the host's network |
+
+## Tests
+
+```
+go test ./...
+```
+
+The tests run against a fake runner and cover:
+
+- escalation through `sudo -n` on a refused socket, and never as root;
+- each failure named by its cause;
+- a name or id never read as an option;
+- mesh-held marking;
+- the environment left out of `inspect`;
+- the restore note on a mesh-held act;
+- prune being a dry run by default and never reaching a volume, a mesh container or `--volumes`;
+- the log merge;
+- size parsing;
+- what the daemon has not yet taken;
+- event filtering;
+- volume ownership;
+- that the tools served are exactly the manifest's `tools`.

modules/docker/cmd/docker-tools/docker_test.go

@@ -0,0 +1,360 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"io/fs"
+	"os"
+	"reflect"
+	"strings"
+	"testing"
+	"time"
+)
+
+type call struct {
+	name string
+	args []string
+}
+
+// fake answers each command by the first rule whose prefix matches "name arg arg…".
+type fake struct {
+	rules []rule
+	calls []call
+}
+
+type rule struct {
+	prefix string
+	ran    Ran
+}
+
+func (f *fake) on(prefix string, r Ran) *fake { f.rules = append(f.rules, rule{prefix, r}); return f }
+
+func (f *fake) run(_ context.Context, name string, args ...string) Ran {
+	f.calls = append(f.calls, call{name, args})
+	line := strings.Join(append([]string{name}, args...), " ")
+	for _, r := range f.rules {
+		if strings.HasPrefix(line, r.prefix) {
+			return r.ran
+		}
+	}
+	return Ran{Status: 1, Stderr: "unexpected: " + line}
+}
+
+func (f *fake) ran(prefix string) bool {
+	for _, c := range f.calls {
+		if strings.HasPrefix(strings.Join(append([]string{c.name}, c.args...), " "), prefix) {
+			return true
+		}
+	}
+	return false
+}
+
+func client(f *fake, uid int) *Client {
+	return &Client{Run: f.run, UID: uid, ReadFile: func(string) ([]byte, error) { return nil, fs.ErrNotExist },
+		Now: func() time.Time { return time.Date(2026, 10, 4, 12, 0, 0, 0, time.UTC) }}
+}
+
+const held = `{"Id":"aaaaaaaaaaaaaaaa","Name":"/mesh-web","Created":"2026-10-01T00:00:00Z","Image":"sha256:img1",
+ "Config":{"Image":"web:1","Labels":{"mesh-host.id":"hello-web.server","mesh-host.spec":"x"},"Env":["PASSWORD=hunter2","PATH=/bin"]},
+ "State":{"Status":"running","Running":true,"StartedAt":"2026-10-01T00:00:01Z","FinishedAt":"0001-01-01T00:00:00Z","Health":{"Status":"healthy"}},
+ "HostConfig":{"RestartPolicy":{"Name":"unless-stopped"},"NetworkMode":"bridge"},
+ "NetworkSettings":{"Ports":{"80/tcp":[{"HostIp":"0.0.0.0","HostPort":"8080"}]}},
+ "Mounts":[{"Type":"volume","Name":"webdata","Destination":"/data","RW":true}]}`
+
+const stray = `{"Id":"bbbbbbbbbbbbbbbb","Name":"/dev-db","Created":"2026-09-01T00:00:00Z","Image":"sha256:img2",
+ "Config":{"Image":"postgres:16","Labels":{"com.docker.compose.project":"dev","com.docker.compose.project.working_dir":"/home/op/dev"}},
+ "State":{"Status":"exited","ExitCode":1,"FinishedAt":"2026-09-02T00:00:00Z"},
+ "HostConfig":{"RestartPolicy":{"Name":"no"}},"NetworkSettings":{"Ports":{}},
+ "Mounts":[{"Type":"volume","Name":"dbdata","Destination":"/var/lib/postgresql/data","RW":true}]}`
+
+func machine() *fake {
+	return (&fake{}).
+		on("docker ps --all --quiet --no-trunc", Ran{Stdout: "aaaaaaaaaaaaaaaa\nbbbbbbbbbbbbbbbb\n"}).
+		on("docker container inspect aaaaaaaaaaaaaaaa bbbbbbbbbbbbbbbb", Ran{Stdout: "[" + held + "," + stray + "]"}).
+		on("docker container inspect mesh-web", Ran{Stdout: "[" + held + "]"}).
+		on("docker container inspect dev-db", Ran{Stdout: "[" + stray + "]"})
+}
+
+func TestARefusedSocketIsAskedAgainThroughSudoWithoutAPromptUnlessThisIsRoot(t *testing.T) {
+	denied := Ran{Status: 1, Stderr: "permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Get ...: dial unix /var/run/docker.sock: connect: permission denied\n"}
+	f := (&fake{}).on("docker ", denied).on("sudo -n docker info", Ran{Stdout: "{}"})
+	if _, err := client(f, 1000).docker(context.Background(), "info", "--format", "{{json .}}"); err != nil {
+		t.Fatal(err)
+	}
+	if !f.ran("sudo -n docker info --format") {
+		t.Fatalf("not escalated: %+v", f.calls)
+	}
+	f = (&fake{}).on("docker ", denied)
+	if _, err := client(f, 0).docker(context.Background(), "info"); err == nil || f.ran("sudo") {
+		t.Fatalf("root escalated or answered: %v %+v", err, f.calls)
+	}
+}
+
+func TestFailuresAreNamedByHowTheyFailed(t *testing.T) {
+	denied := Ran{Status: 1, Stderr: "permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock\n"}
+	cases := map[string]*fake{
+		"may not escalate without a prompt": (&fake{}).on("docker ", denied).on("sudo ", Ran{Status: 1, Stderr: "sudo: a password is required\n"}),
+		"sudo is not installed":             (&fake{}).on("docker ", denied).on("sudo ", Ran{Status: 127, Err: "ENOENT"}),
+		"docker is not installed":           (&fake{}).on("docker ", Ran{Status: 127, Err: "ENOENT"}),
+		"daemon is not answering":           (&fake{}).on("docker ", Ran{Status: 1, Stderr: "Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?\n"}),
+		"did not answer: no answer within":  (&fake{}).on("docker ", Ran{Status: 124, Err: "no answer within 20 s"}),
+		"docker info failed (3): boom":      (&fake{}).on("docker ", Ran{Status: 3, Stderr: "boom\n"}),
+	}
+	for want, f := range cases {
+		_, err := client(f, 1000).docker(context.Background(), "info")
+		if err == nil || !strings.Contains(err.Error(), want) {
+			t.Errorf("want %q, got %v", want, err)
+		}
+	}
+}
+
+func TestANameIsNeverAnOption(t *testing.T) {
+	for _, bad := range []string{"--help", "-v", "", "a b", "x;y"} {
+		if _, err := Ref(bad); err == nil {
+			t.Errorf("%q accepted", bad)
+		}
+	}
+	for _, good := range []string{"mesh-web", "aaaaaaaaaaaa", "registry.mesh.internal:5100/x@sha256:abc", "dev_db.1"} {
+		if _, err := Ref(good); err != nil {
+			t.Errorf("%q refused: %v", good, err)
+		}
+	}
+	f := machine()
+	for _, verb := range []string{"start", "stop", "restart"} {
+		if _, err := client(f, 1000).Act(context.Background(), verb, "--rm"); err == nil {
+			t.Errorf("%s took an option", verb)
+		}
+	}
+	if len(f.calls) != 0 {
+		t.Fatalf("docker was called: %+v", f.calls)
+	}
+}
+
+func TestEveryContainerIsListedAndTheMeshsAreMarked(t *testing.T) {
+	c := client(machine(), 1000)
+	all, err := c.Containers(context.Background(), "", "", "")
+	if err != nil || len(all) != 2 {
+		t.Fatalf("%v %+v", err, all)
+	}
+	web, db := all[1], all[0]
+	if !web.MeshHeld || web.HeldBy != "hello-web.server" || web.Module != "hello-web" || web.Health != "healthy" {
+		t.Errorf("held: %+v", web)
+	}
+	if !reflect.DeepEqual(web.Ports, []string{"0.0.0.0:8080->80/tcp"}) || web.Mounts[0].Name != "webdata" {
+		t.Errorf("ports/mounts: %+v", web)
+	}
+	if db.MeshHeld || db.Compose != "dev" || db.ComposeDir != "/home/op/dev" || db.FinishedAt == "" {
+		t.Errorf("stray: %+v", db)
+	}
+	mesh, _ := c.Containers(context.Background(), "mesh", "", "")
+	other, _ := c.Containers(context.Background(), "other", "", "")
+	if len(mesh) != 1 || mesh[0].Name != "mesh-web" || len(other) != 1 || other[0].Name != "dev-db" {
+		t.Errorf("held filter: %+v / %+v", mesh, other)
+	}
+	if _, err := c.Containers(context.Background(), "mine", "", ""); err == nil {
+		t.Error("an unknown held filter was accepted")
+	}
+}
+
+func TestNoContainersIsAnEmptyListAndAFailureIsAnError(t *testing.T) {
+	got, err := client((&fake{}).on("docker ps", Ran{}), 1000).Containers(context.Background(), "", "", "")
+	if err != nil || got == nil || len(got) != 0 {
+		t.Fatalf("%v %v", got, err)
+	}
+	if _, err := client((&fake{}).on("docker ps", Ran{Status: 1, Stderr: "Cannot connect to the Docker daemon\n"}), 1000).Containers(context.Background(), "", "", ""); err == nil {
+		t.Fatal("a daemon that does not answer read as no containers")
+	}
+}
+
+func TestInspectLeavesTheEnvironmentsValuesOut(t *testing.T) {
+	got, err := client(machine(), 1000).Inspect(context.Background(), "mesh-web")
+	if err != nil {
+		t.Fatal(err)
+	}
+	b, _ := json.Marshal(got)
+	if strings.Contains(string(b), "hunter2") || !strings.Contains(string(b), `"PASSWORD"`) || got["mesh_held"] != true {
+		t.Fatalf("%s", b)
+	}
+}
+
+func TestActingOnAMeshContainerSaysTheHostRestoresIt(t *testing.T) {
+	f := machine().on("docker stop", Ran{}).on("docker start", Ran{})
+	got, err := client(f, 1000).Act(context.Background(), "stop", "mesh-web")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !f.ran("docker stop --time 10 mesh-web") || got["mesh_held"] != true || !strings.Contains(got["note"].(string), "host restores") {
+		t.Fatalf("%v %+v", got, f.calls)
+	}
+	got, _ = client(f, 1000).Act(context.Background(), "start", "dev-db")
+	if _, noted := got["note"]; noted || got["mesh_held"] != false {
+		t.Fatalf("a stray was noted: %v", got)
+	}
+}
+
+func TestPruneIsADryRunByDefaultAndNeverTouchesAVolumeOrAMeshContainer(t *testing.T) {
+	f := machine().
+		on("docker image ls --no-trunc --filter dangling=true", Ran{Stdout: `{"ID":"sha256:dead","Size":"1.5GB"}` + "\n"}).
+		on("docker system df --format", Ran{Stdout: `{"Type":"Build Cache","TotalCount":"3","Size":"2GB","Reclaimable":"1GB"}` + "\n"}).
+		on("docker image prune", Ran{Stdout: "Deleted Images:\nx\n\nTotal reclaimed space: 1.5GB\n"}).
+		on("docker builder prune", Ran{Stdout: "Total:\t1GB\n"}).
+		on("docker container rm", Ran{})
+	c := client(f, 1000)
+	got, err := c.Prune(context.Background(), PruneAsk{Images: true, BuildCache: true, Containers: true, DryRun: true})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if f.ran("docker image prune") || f.ran("docker builder prune") || f.ran("docker container rm") {
+		t.Fatalf("a dry run removed something: %+v", f.calls)
+	}
+	if got["images"].(map[string]any)["dangling"] != 1 || !reflect.DeepEqual(got["containers"].(map[string]any)["stopped_not_held"], []string{"dev-db"}) {
+		t.Fatalf("%v", got)
+	}
+	got, err = c.Prune(context.Background(), PruneAsk{Images: true, BuildCache: true, Containers: true, OlderThanH: 24})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !f.ran("docker image prune --force --filter until=24h") || !f.ran("docker builder prune --force --filter until=24h") || !f.ran("docker container rm dev-db") {
+		t.Fatalf("not pruned: %+v", f.calls)
+	}
+	for _, c := range f.calls {
+		line := strings.Join(c.args, " ")
+		if strings.Contains(line, "volume") || strings.Contains(line, "mesh-web") && c.args[0] != "container" || strings.Contains(line, "--volumes") || strings.Contains(line, "--all") && c.args[0] != "ps" {
+			t.Errorf("prune reached too far: %s", line)
+		}
+	}
+	if got["images"].(map[string]any)["reclaimed"] != "1.5GB" || got["build_cache"].(map[string]any)["reclaimed"] != "1GB" {
+		t.Errorf("reclaimed: %v", got)
+	}
+}
+
+func TestLogsMergeBothStreamsInOrderAndKeepTheTail(t *testing.T) {
+	f := (&fake{}).on("docker logs", Ran{Stdout: "2026-10-04T10:00:01Z out one\n2026-10-04T10:00:03Z out two\n", Stderr: "2026-10-04T10:00:02Z err one\n"})
+	got, err := client(f, 1000).Logs(context.Background(), "web", 2, "30m")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !reflect.DeepEqual(got["lines"], []string{"2026-10-04T10:00:02Z err one", "2026-10-04T10:00:03Z out two"}) {
+		t.Fatalf("%v", got["lines"])
+	}
+	if !f.ran("docker logs --timestamps --tail 2 --since 30m web") {
+		t.Fatalf("%+v", f.calls)
+	}
+	if _, err := client(f, 1000).Logs(context.Background(), "web", 2, "--follow"); err == nil {
+		t.Fatal("since took an option")
+	}
+	f = (&fake{}).on("docker logs", Ran{Status: 1, Stderr: "Error response from daemon: No such container: nope\n"})
+	if _, err := client(f, 1000).Logs(context.Background(), "nope", 2, ""); err == nil {
+		t.Fatal("a missing container read as no lines")
+	}
+}
+
+func TestSizesAreReadAsDockerPrintsThem(t *testing.T) {
+	for in, want := range map[string]int64{"0B": 0, "55.63GB": 55630000000, "33.2MiB": 34812723, "1.5kB": 1500, "12MB (34%)": 12000000, "N/A": -1} {
+		if got := Bytes(in); got != want {
+			t.Errorf("%s: %d, want %d", in, got, want)
+		}
+	}
+}
+
+func TestDaemonConfigSaysWhatTheDaemonHasNotTakenYet(t *testing.T) {
+	f := (&fake{}).on("docker info", Ran{Stdout: `{"ServerVersion":"29.8.2","LiveRestoreEnabled":false,"LoggingDriver":"json-file","RegistryConfig":{"IndexConfigs":{"docker.io":{"Secure":true},"registry.mesh.internal:5100":{"Secure":false}}}}`})
+	c := client(f, 1000)
+	c.ReadFile = func(string) ([]byte, error) {
+		return []byte(`{"live-restore": true, "dns": ["10.0.0.1"], "log-driver": "local"}`), nil
+	}
+	got, err := c.DaemonConfig(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+	pending := strings.Join(got["pending"].([]string), "\n")
+	if !strings.Contains(pending, "live-restore is true in the file and false") || !strings.Contains(pending, "log-driver is local") {
+		t.Errorf("pending: %s", pending)
+	}
+	if !reflect.DeepEqual(got["daemon"].(map[string]any)["InsecureRegistries"], []string{"registry.mesh.internal:5100"}) {
+		t.Errorf("registries: %v", got["daemon"])
+	}
+	if !reflect.DeepEqual(got["read_only_at_start"], []string{"dns", "log-driver"}) {
+		t.Errorf("start-only: %v", got["read_only_at_start"])
+	}
+	c.ReadFile = func(string) ([]byte, error) { return nil, os.ErrNotExist }
+	got, _ = c.DaemonConfig(context.Background())
+	if !strings.HasPrefix(got["file_state"].(string), "absent") {
+		t.Errorf("absent: %v", got["file_state"])
+	}
+	c.ReadFile = func(string) ([]byte, error) { return nil, errors.New("permission denied") }
+	got, _ = c.DaemonConfig(context.Background())
+	if !strings.HasPrefix(got["file_state"].(string), "unreadable") {
+		t.Errorf("unreadable: %v", got["file_state"])
+	}
+}
+
+func TestEventsAreABoundedWindowWithoutExecNoise(t *testing.T) {
+	out := `{"Type":"container","Action":"exec_start: pg_isready","Actor":{"ID":"aaaaaaaaaaaaaaaa","Attributes":{"name":"db"}},"timeNano":1}
+{"Type":"container","Action":"die","Actor":{"ID":"aaaaaaaaaaaaaaaa","Attributes":{"name":"web","mesh-host.id":"hello-web.server","exitCode":"137"}},"timeNano":2}
+`
+	f := (&fake{}).on("docker events", Ran{Stdout: out})
+	got, err := client(f, 1000).Events(context.Background(), 30, "container", 10, false)
+	if err != nil {
+		t.Fatal(err)
+	}
+	evs := got["events"].([]map[string]any)
+	if len(evs) != 1 || evs[0]["action"] != "die" || evs[0]["mesh_held"] != true || evs[0]["exit_code"] != "137" {
+		t.Fatalf("%v", evs)
+	}
+	if !f.ran("docker events --since 30m --until 0s --format {{json .}} --filter type=container") {
+		t.Fatalf("%+v", f.calls)
+	}
+	if _, err := client(f, 1000).Events(context.Background(), 30, "secret", 10, false); err == nil {
+		t.Fatal("an unknown type was accepted")
+	}
+}
+
+func TestVolumesSayWhoMountsThemAndWhetherTheMeshDoes(t *testing.T) {
+	f := machine().
+		on("docker volume ls --quiet", Ran{Stdout: "webdata\ndbdata\nloose\n"}).
+		on("docker volume inspect", Ran{Stdout: `[{"Name":"webdata","Driver":"local"},{"Name":"dbdata","Driver":"local"},{"Name":"loose","Driver":"local","Labels":{"com.docker.volume.anonymous":""}}]`})
+	got, err := client(f, 1000).Volumes(context.Background(), false, false)
+	if err != nil {
+		t.Fatal(err)
+	}
+	vols := got["volumes"].([]map[string]any)
+	if vols[0]["mesh_held"] != true || vols[1]["mesh_held"] != false || len(vols[2]["mounted_by"].([]map[string]any)) != 0 || vols[2]["anonymous"] != true {
+		t.Fatalf("%v", vols)
+	}
+	got, _ = client(f, 1000).Volumes(context.Background(), true, false)
+	if got["count"] != 1 {
+		t.Fatalf("unmounted: %v", got)
+	}
+}
+
+func TestImagesNameTheirUsers(t *testing.T) {
+	f := machine().on("docker image ls", Ran{Stdout: `{"ID":"sha256:img1","Repository":"web","Tag":"1","Size":"100MB"}
+{"ID":"sha256:img3","Repository":"<none>","Tag":"<none>","Size":"2GB"}
+`})
+	got, err := client(f, 1000).Images(context.Background(), "", "", 10)
+	if err != nil {
+		t.Fatal(err)
+	}
+	imgs := got["images"].([]Image)
+	if imgs[0].ID != "sha256:img3" || !imgs[0].Dangling || imgs[1].UsedBy[0] != "mesh-web" || !imgs[1].MeshUsed {
+		t.Fatalf("%+v", imgs)
+	}
+	got, _ = client(f, 1000).Images(context.Background(), "unused", "", 10)
+	if got["count"] != 1 {
+		t.Fatalf("unused: %v", got)
+	}
+}
+
+func TestProblemsNameWhyAndUnlabelledIsTheCleanupList(t *testing.T) {
+	c := client(machine(), 1000)
+	p, err := c.Problems(context.Background())
+	if err != nil || len(p) != 1 || p[0]["name"] != "dev-db" || p[0]["why"].([]string)[0] != "exited 1" {
+		t.Fatalf("%v %v", p, err)
+	}
+	u, err := c.Unlabelled(context.Background())
+	if err != nil || u["count"] != 1 {
+		t.Fatalf("%v %v", u, err)
+	}
+}

modules/docker/cmd/docker-tools/main.go

@@ -0,0 +1,279 @@
+// docker's Go tools bundle (novox/hq ADR 0188, ADR 0193): a process the node's tool runtime launches
+// and speaks MCP over stdio to, through the Go SDK. It answers for every container on this machine —
+// the mesh's and every other — and for the runtime's images, networks, volumes, events and
+// configuration. It runs as the operator account (ADR 0175 §4); docker.go says how it reaches the
+// daemon's socket. The host applies the module's resources; these tools answer about the runtime.
+package main
+
+import (
+	"context"
+	"fmt"
+	"math"
+	"os"
+	"strings"
+
+	stdio "git.novox.be/novox/mesh-sdk/go"
+)
+
+func main() {
+	// An empty name serves as the module the runtime names (MESH_SERVED_MODULE): docker.
+	if err := stdio.Serve("", tools(NewClient())); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
+
+var containerArg = map[string]any{"type": "string", "description": "the container's name or id"}
+
+func tools(c *Client) []stdio.Tool {
+	ctx := context.Background()
+	act := func(verb, description string) stdio.Tool {
+		return stdio.Tool{
+			Name: "docker_" + verb, Description: description,
+			Input: map[string]any{"container": containerArg},
+			Run: func(args map[string]any) (any, error) {
+				ref, err := text(args, "container")
+				if err != nil {
+					return nil, err
+				}
+				return c.Act(ctx, verb, ref)
+			},
+		}
+	}
+	return []stdio.Tool{
+		{
+			Name: "docker_list",
+			Description: "Every container on this machine — the mesh's and every other — with its image, state, health, restarts, " +
+				"published ports, mounts, compose project, and mesh_held/held_by (the assignment that holds it).",
+			Input: map[string]any{
+				"held":  map[string]any{"type": "string", "enum": []string{"all", "mesh", "other"}, "description": "whose: all (default), the mesh's, or the others"},
+				"state": map[string]any{"type": "string", "description": "only containers in this state (running, exited, created, restarting, paused, dead)"},
+				"match": map[string]any{"type": "string", "description": "only containers whose name or image contains this"},
+			},
+			Run: func(args map[string]any) (any, error) {
+				list, err := c.Containers(ctx, optional(args, "held"), optional(args, "state"), optional(args, "match"))
+				if err != nil {
+					return nil, err
+				}
+				return map[string]any{"count": len(list), "containers": list}, nil
+			},
+		},
+		{
+			Name:        "docker_inspect",
+			Description: "One container whole, as docker inspects it, with mesh_held; its environment's values are left out (names kept), because that is where a container's secrets are.",
+			Input:       map[string]any{"container": containerArg},
+			Run: func(args map[string]any) (any, error) {
+				ref, err := text(args, "container")
+				if err != nil {
+					return nil, err
+				}
+				return c.Inspect(ctx, ref)
+			},
+		},
+		{
+			Name:        "docker_logs",
+			Description: "The last lines one container wrote, both streams merged in order, each with its timestamp (default 200, at most 2000 lines; a line is cut at 4 KiB).",
+			Input: map[string]any{
+				"container": containerArg,
+				"lines":     map[string]any{"type": "integer", "description": "how many lines from the end (default 200, at most 2000)"},
+				"since":     map[string]any{"type": "string", "description": "only lines since then: a duration such as 30m or 2h, or a time"},
+			},
+			Run: func(args map[string]any) (any, error) {
+				ref, err := text(args, "container")
+				if err != nil {
+					return nil, err
+				}
+				n, err := bounded(args, "lines", 200, 2000)
+				if err != nil {
+					return nil, err
+				}
+				return c.Logs(ctx, ref, n, optional(args, "since"))
+			},
+		},
+		{
+			Name:        "docker_stats",
+			Description: "What the running containers use now — CPU, memory, network and disk I/O, processes — the heaviest by memory first; or one container's.",
+			Input:       map[string]any{"container": map[string]any{"type": "string", "description": "one container (optional)"}},
+			Run: func(args map[string]any) (any, error) {
+				stats, err := c.Stats(ctx, optional(args, "container"))
+				if err != nil {
+					return nil, err
+				}
+				return map[string]any{"count": len(stats), "containers": stats}, nil
+			},
+		},
+		act("start", "Start one container. A container the mesh holds is started too, and the answer says the host restores what its declaration says at its next apply."),
+		act("stop", "Stop one container (ten seconds, then killed). For a container the mesh holds, the answer says the host will start it again at its next apply if its declaration says running."),
+		act("restart", "Restart one container (ten seconds to stop, then killed); the answer says whether the mesh holds it."),
+		{
+			Name:        "docker_top",
+			Description: "The processes running inside one container: pid, user, elapsed time, CPU, resident memory and command.",
+			Input:       map[string]any{"container": containerArg},
+			Run: func(args map[string]any) (any, error) {
+				ref, err := text(args, "container")
+				if err != nil {
+					return nil, err
+				}
+				return c.Top(ctx, ref)
+			},
+		},
+		{
+			Name: "docker_images",
+			Description: "The images on this machine, the largest first, each with its size and the containers using it (and whether one of them is the mesh's). " +
+				"filter: all, dangling, unused or used.",
+			Input: map[string]any{
+				"filter": map[string]any{"type": "string", "enum": []string{"all", "dangling", "unused", "used"}, "description": "which images (default all)"},
+				"match":  map[string]any{"type": "string", "description": "only images whose repository:tag contains this"},
+				"limit":  map[string]any{"type": "integer", "description": "how many to show (default 100, at most 1000); count says how many matched"},
+			},
+			Run: func(args map[string]any) (any, error) {
+				n, err := bounded(args, "limit", 100, 1000)
+				if err != nil {
+					return nil, err
+				}
+				return c.Images(ctx, optional(args, "filter"), optional(args, "match"), n)
+			},
+		},
+		{
+			Name: "docker_prune",
+			Description: "Reclaim space: dangling images and unused build cache, and — only when containers is true — stopped containers the mesh does not hold. " +
+				"Never a volume, never a container the mesh holds, never an image a container uses. A dry run by default: it lists what would go; dry_run false removes it.",
+			Input: map[string]any{
+				"dry_run":          map[string]any{"type": "boolean", "description": "list only (default true)"},
+				"images":           map[string]any{"type": "boolean", "description": "dangling images (default true)"},
+				"build_cache":      map[string]any{"type": "boolean", "description": "build cache nothing refers to (default true)"},
+				"containers":       map[string]any{"type": "boolean", "description": "stopped containers the mesh does not hold (default false); what they mounted is kept"},
+				"older_than_hours": map[string]any{"type": "integer", "description": "only what is older than this many hours (default 0: any age)"},
+			},
+			Run: func(args map[string]any) (any, error) {
+				older := 0
+				if v, ok := args["older_than_hours"]; ok && v != nil && v != float64(0) {
+					n, err := bounded(args, "older_than_hours", 0, 24*365)
+					if err != nil {
+						return nil, err
+					}
+					older = n
+				}
+				return c.Prune(ctx, PruneAsk{
+					DryRun: flag(args, "dry_run", true), Images: flag(args, "images", true), BuildCache: flag(args, "build_cache", true),
+					Containers: flag(args, "containers", false), OlderThanH: older,
+				})
+			},
+		},
+		{
+			Name:        "docker_disk_usage",
+			Description: "What the runtime takes on disk (docker system df -v): per kind — images, containers, volumes, build cache — the total, the active and the reclaimable, and the largest of each.",
+			Input:       map[string]any{"top": map[string]any{"type": "integer", "description": "how many of the largest per kind (default 10, at most 100)"}},
+			Run: func(args map[string]any) (any, error) {
+				n, err := bounded(args, "top", 10, 100)
+				if err != nil {
+					return nil, err
+				}
+				return c.DiskUsage(ctx, n)
+			},
+		},
+		{
+			Name:        "docker_networks",
+			Description: "Every network the runtime has: driver, scope, subnets and gateway, and the running containers on it with their addresses and whether the mesh holds them.",
+			Run:         func(map[string]any) (any, error) { return c.Networks(ctx) },
+		},
+		{
+			Name:        "docker_volumes",
+			Description: "Every volume with the containers mounting it, whether the mesh holds any of them, whether it is anonymous, its compose project, and — when sizes is true (slower) — its size.",
+			Input: map[string]any{
+				"unmounted": map[string]any{"type": "boolean", "description": "only volumes no container mounts (default false)"},
+				"sizes":     map[string]any{"type": "boolean", "description": "measure each volume (default false: it walks every volume)"},
+			},
+			Run: func(args map[string]any) (any, error) {
+				return c.Volumes(ctx, flag(args, "unmounted", false), flag(args, "sizes", false))
+			},
+		},
+		{
+			Name:        "docker_events",
+			Description: "What the runtime did in a window ending now (default the last 60 minutes, at most 24 hours): containers created, started, died, health changes, images pulled — with mesh_held. Exec events are left out unless asked.",
+			Input: map[string]any{
+				"minutes": map[string]any{"type": "integer", "description": "how far back (default 60, at most 1440)"},
+				"type":    map[string]any{"type": "string", "description": "only one kind: container, image, network, volume, daemon, plugin or builder"},
+				"limit":   map[string]any{"type": "integer", "description": "the latest this many (default 200, at most 2000)"},
+				"execs":   map[string]any{"type": "boolean", "description": "include exec_* events (default false: health checks make many)"},
+			},
+			Run: func(args map[string]any) (any, error) {
+				minutes, err := bounded(args, "minutes", 60, 1440)
+				if err != nil {
+					return nil, err
+				}
+				limit, err := bounded(args, "limit", 200, 2000)
+				if err != nil {
+					return nil, err
+				}
+				return c.Events(ctx, minutes, optional(args, "type"), limit, flag(args, "execs", false))
+			},
+		},
+		{
+			Name: "docker_daemon_config",
+			Description: "The runtime's configuration: /etc/docker/daemon.json as it is on disk, the daemon's essentials as it runs now (docker info: version, storage and logging drivers, " +
+				"live restore, root directory, insecure registries, warnings), and where the two differ — keys a reload or only a restart would take.",
+			Run: func(map[string]any) (any, error) { return c.DaemonConfig(ctx) },
+		},
+		{
+			Name:        "docker_unlabelled",
+			Description: "The containers the mesh does not hold — the cleanup list — each with its image, state, compose project and directory, ports and mounts.",
+			Run:         func(map[string]any) (any, error) { return c.Unlabelled(ctx) },
+		},
+		{
+			Name:        "docker_problems",
+			Description: "Every container that is not well: unhealthy, restarting, dead, killed for memory, exited with a failure, or restarted five times or more — with whether the mesh holds it.",
+			Run: func(map[string]any) (any, error) {
+				p, err := c.Problems(ctx)
+				if err != nil {
+					return nil, err
+				}
+				return map[string]any{"count": len(p), "containers": p}, nil
+			},
+		},
+		{
+			Name:        "docker_ports",
+			Description: "Every port the containers publish on this machine (address:port -> container port), and the containers on the host's network, which publish whatever they listen on.",
+			Run: func(map[string]any) (any, error) {
+				p, err := c.Ports(ctx)
+				if err != nil {
+					return nil, err
+				}
+				return map[string]any{"count": len(p), "ports": p}, nil
+			},
+		},
+	}
+}
+
+func text(args map[string]any, key string) (string, error) {
+	s, _ := args[key].(string)
+	if s = strings.TrimSpace(s); s == "" {
+		return "", fmt.Errorf("%s is required", key)
+	}
+	return s, nil
+}
+
+func optional(args map[string]any, key string) string {
+	s, _ := args[key].(string)
+	return strings.TrimSpace(s)
+}
+
+func flag(args map[string]any, key string, def bool) bool {
+	if b, ok := args[key].(bool); ok {
+		return b
+	}
+	return def
+}
+
+// bounded is a whole number argument, defaulted when absent and held to a ceiling.
+func bounded(args map[string]any, key string, def, most int) (int, error) {
+	v, ok := args[key]
+	if !ok || v == nil {
+		return def, nil
+	}
+	f, ok := v.(float64)
+	if !ok || f != math.Trunc(f) || f < 1 {
+		return 0, fmt.Errorf("%s must be a whole number of at least 1", key)
+	}
+	return int(math.Min(f, float64(most))), nil
+}

modules/docker/cmd/docker-tools/runner.go

@@ -0,0 +1,59 @@
+package main
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"os/exec"
+	"strings"
+	"time"
+)
+
+// Ran is what a command did: its output, its exit status, and why it never ran to an answer.
+type Ran struct {
+	Stdout string
+	Stderr string
+	Status int
+	// Err is "ENOENT" when the program is not installed, or says it was ended for taking too long.
+	Err string
+}
+
+// Runner runs one command, so every tool can be tested without a daemon.
+type Runner func(ctx context.Context, name string, args ...string) Ran
+
+// CallTimeout is how long one docker command may take: below the runtime's thirty-second call
+// limit, so a daemon that hangs is answered as such rather than as a call the runtime gave up on.
+const CallTimeout = 20 * time.Second
+
+// ExecRunner runs a command on this machine, bounded by CallTimeout.
+func ExecRunner(ctx context.Context, name string, args ...string) Ran {
+	ctx, cancel := context.WithTimeout(ctx, CallTimeout)
+	defer cancel()
+	cmd := exec.CommandContext(ctx, name, args...)
+	var out, errb bytes.Buffer
+	cmd.Stdout, cmd.Stderr = &out, &errb
+	err := cmd.Run()
+	r := Ran{Stdout: out.String(), Stderr: errb.String()}
+	var exitErr *exec.ExitError
+	switch {
+	case errors.Is(ctx.Err(), context.DeadlineExceeded):
+		r.Status, r.Err = 124, fmt.Sprintf("no answer within %d s", int(CallTimeout/time.Second))
+	case errors.Is(err, exec.ErrNotFound):
+		r.Status, r.Err = 127, "ENOENT"
+	case errors.As(err, &exitErr):
+		r.Status = exitErr.ExitCode()
+	case err != nil:
+		r.Status, r.Err = 1, err.Error()
+	}
+	return r
+}
+
+func firstLine(s string) string {
+	for _, l := range strings.Split(s, "\n") {
+		if l = strings.TrimSpace(l); l != "" {
+			return l
+		}
+	}
+	return ""
+}

modules/docker/cmd/docker-tools/tools_test.go

@@ -0,0 +1,60 @@
+package main
+
+import (
+	"encoding/json"
+	"os"
+	"reflect"
+	"sort"
+	"strings"
+	"testing"
+)
+
+func TestTheToolsServedAreTheToolsTheManifestNames(t *testing.T) {
+	raw, err := os.ReadFile("../../module.json")
+	if err != nil {
+		t.Fatal(err)
+	}
+	var m struct {
+		Tools []string `json:"tools"`
+	}
+	if err := json.Unmarshal(raw, &m); err != nil {
+		t.Fatal(err)
+	}
+	served := []string{}
+	for _, tool := range tools(client(&fake{}, 1000)) {
+		if !strings.HasPrefix(tool.Name, "docker_") || tool.Description == "" || tool.Run == nil {
+			t.Errorf("tool %q", tool.Name)
+		}
+		served = append(served, tool.Name)
+	}
+	sort.Strings(served)
+	listed := append([]string{}, m.Tools...)
+	sort.Strings(listed)
+	if !reflect.DeepEqual(served, listed) {
+		t.Fatalf("served %v, manifest %v", served, listed)
+	}
+}
+
+func TestNumbersAreDefaultedAndBounded(t *testing.T) {
+	if n, _ := bounded(map[string]any{}, "lines", 200, 2000); n != 200 {
+		t.Error(n)
+	}
+	if n, _ := bounded(map[string]any{"lines": float64(99999)}, "lines", 200, 2000); n != 2000 {
+		t.Error(n)
+	}
+	for _, bad := range []any{float64(0), float64(-1), float64(1.5), "10"} {
+		if _, err := bounded(map[string]any{"lines": bad}, "lines", 200, 2000); err == nil {
+			t.Errorf("%v accepted", bad)
+		}
+	}
+}
+
+func TestAStopFromTheToolNeedsAContainer(t *testing.T) {
+	for _, tool := range tools(client(&fake{}, 1000)) {
+		if tool.Name == "docker_stop" {
+			if _, err := tool.Run(map[string]any{}); err == nil {
+				t.Fatal("a stop without a container was accepted")
+			}
+		}
+	}
+}

modules/docker/go.mod

@@ -0,0 +1,5 @@
+module docker
+
+go 1.22
+
+require git.novox.be/novox/mesh-sdk/go v0.1.6

modules/docker/go.sum

@@ -0,0 +1,2 @@
+git.novox.be/novox/mesh-sdk/go v0.1.6 h1:9qzdYONYbJdWcu6sxQcq9v1LI0JxcfkiKYkMUzJSkVQ=
+git.novox.be/novox/mesh-sdk/go v0.1.6/go.mod h1:GFuZUElBZ9A++mxgIKo97aXXo+kV0uJ/UkbhQPPIbrY=

modules/docker/module.json

@@ -0,0 +1,94 @@
+{
+  "module": "docker",
+  "version": "1",
+  "capabilities": [
+    "package-manager",
+    "service-manager",
+    "privileged"
+  ],
+  "claims": [
+    {
+      "name": "node-container-runtime",
+      "scope": "node"
+    }
+  ],
+  "tools": [
+    "docker_list",
+    "docker_inspect",
+    "docker_logs",
+    "docker_stats",
+    "docker_start",
+    "docker_stop",
+    "docker_restart",
+    "docker_top",
+    "docker_images",
+    "docker_prune",
+    "docker_disk_usage",
+    "docker_networks",
+    "docker_volumes",
+    "docker_events",
+    "docker_daemon_config",
+    "docker_unlabelled",
+    "docker_problems",
+    "docker_ports"
+  ],
+  "resources": [
+    {
+      "id": "package",
+      "type": "package",
+      "package": "docker"
+    },
+    {
+      "id": "buildx",
+      "type": "package",
+      "package": "docker-buildx"
+    },
+    {
+      "id": "socket",
+      "type": "service",
+      "unit": "docker.socket",
+      "state": "running",
+      "boot": "enabled"
+    },
+    {
+      "id": "prune-service",
+      "type": "file",
+      "path": "/etc/systemd/system/docker-prune.service",
+      "mode": "0644",
+      "content": "# Generated by the mesh. Do not edit — module docker writes this file and replaces it at every push.\n[Unit]\nDescription=Prune dangling images and unused build cache (the mesh's docker module)\n# Never volumes, never a container, never an image a container uses: dangling\n# images and build cache nothing refers to, unused for a week. What a person\n# prunes beyond that is docker_prune's, by hand.\nAfter=docker.service\nConditionPathExists=/run/docker.sock\n\n[Service]\nType=oneshot\nNice=19\nIOSchedulingClass=idle\nExecStart=/usr/bin/docker image prune --force --filter until=168h\nExecStart=/usr/bin/docker builder prune --force --filter until=168h\n"
+    },
+    {
+      "id": "prune-timer",
+      "type": "file",
+      "path": "/etc/systemd/system/docker-prune.timer",
+      "mode": "0644",
+      "content": "# Generated by the mesh. Do not edit — module docker writes this file and replaces it at every push.\n[Unit]\nDescription=Weekly prune of dangling images and unused build cache (the mesh's docker module)\n\n[Timer]\nOnCalendar=weekly\nRandomizedDelaySec=1h\nPersistent=true\n\n[Install]\nWantedBy=timers.target\n"
+    },
+    {
+      "id": "prune",
+      "type": "service",
+      "unit": "docker-prune.timer",
+      "state": "running",
+      "boot": "enabled",
+      "restart-on": [
+        "prune-service",
+        "prune-timer"
+      ]
+    }
+  ],
+  "build": {
+    "artifacts": [
+      {
+        "name": "tools",
+        "kind": "bundle",
+        "language": "go",
+        "system": "arch",
+        "from": "cmd/docker-tools",
+        "binary": "docker-tools",
+        "loads": [
+          "docker-tools"
+        ]
+      }
+    ]
+  }
+}

modules/dunst/README.md

@@ -0,0 +1,60 @@
+# dunst
+
+The notifier as a module (novox/hq ADR 0208, research 026/05).
+
+- Installs `dunst`, and `libnotify` for `notify-send`, the client every program and these tools use.
+- Claims the mesh's `node-notifier` seat and serves its verbs `send` and `history`.
+- Owns `~/.config/dunst/dunstrc` and the directory `~/.config/dunst/dunstrc.d/`. Another module's
+  rule is that module's own file in the directory (ADR 0208 §4). dunst reads the directory after
+  `dunstrc`, so a drop-in outranks it.
+- **Starts nothing.** The package registers dunst with D-Bus, which starts it on the first
+  notification, inside the account's service manager. There is no autostart line, no unit and no
+  session-start contribution.
+- **Requires no display of its own.** dunst speaks both X11 and Wayland and picks the one the session
+  has, so it serves an X session and a later sway one alike.
+
+## Tools
+
+Every tool goes over the account's session bus. None needs the screen, and each answers clearly when
+the account is not logged in.
+
+| tool | does |
+|---|---|
+| `node-notifier.send` | a notification: title, body, urgency, sender, icon, how long; answers its id |
+| `node-notifier.history` | what was shown, newest first, with how long ago |
+| `dunst_pause` / `dunst_resume` | do not disturb: notifications are held back, not lost |
+| `dunst_close_all` | clear the screen; the history keeps them |
+| `dunst_rules` | the rules the running notifier holds, and the files they come from |
+| `dunst_count` | shown, waiting, in history, and whether paused |
+
+## What it chose, and what it improves
+
+The workstations' files differed: one had the notifications bottom-right, 15 % transparent and with
+rounded corners; the other top-right, opaque and square. This module takes the second, because the
+rest of the desktop is square and opaque, and the top-right corner sits under the bar that shows the
+count. The file keeps only the settings that differ from dunst's defaults.
+
+- **The context menu works.** It called `/usr/bin/dmenu`, installed on neither machine. It now calls
+  `dmenu`, the seat command of whichever module holds `node-launcher` (`rofi` on the workstations).
+- **The face is the interface one,** Inter (research 026/04), instead of a monospace Nerd font.
+- `icon_path`, which named two directories of an icon theme that is not installed, is gone. The icon
+  theme is looked up recursively.
+
+## What it leaves as found
+
+- `~/.config/dunst/dunstrc.d/50-slack.conf`, the Slack rule. It becomes the Slack module's own drop-in
+  when there is one, and until then it is the operator's file in a directory this module owns.
+
+## Migration (ADR 0182)
+
+- The first push keeps the found `dunstrc` once, then writes the module's.
+- **The desktop runs two notification daemons** because its session began before the session bus
+  fix (research 026/01). That ends at the next login, and nothing here starts a second one.
+  `dunst_count` after logging in again shows the one daemon's counts.
+
+## Blockers
+
+- `node-notifier` is ADR 0208's seat. Until the controller knows it, `mctl` reads the claim as
+  unknown.
+- `dunst_rules` and the counts ask the running notifier. When none runs, the bus starts one, which
+  needs a session to draw on.

modules/dunst/cmd/dunst-tools/args.go

@@ -0,0 +1,97 @@
+// Reading a tool's arguments: JSON numbers arrive as float64, and a missing argument is its default.
+// The same in every desktop module that carries it.
+package main
+
+import (
+	"fmt"
+	"math"
+	"strings"
+	"time"
+)
+
+// text is a string argument, trimmed; required says an empty one is refused.
+func text(args map[string]any, key string, required bool) (string, error) {
+	v, present := args[key]
+	if !present || v == nil {
+		if required {
+			return "", fmt.Errorf("%s is required", key)
+		}
+		return "", nil
+	}
+	s, ok := v.(string)
+	if !ok {
+		return "", fmt.Errorf("%s is a string, not %T", key, v)
+	}
+	s = strings.TrimSpace(s)
+	if s == "" && required {
+		return "", fmt.Errorf("%s is required", key)
+	}
+	return s, nil
+}
+
+// whole is a whole-number argument within [least, most], or def when absent.
+func whole(args map[string]any, key string, def, least, most int) (int, error) {
+	v, present := args[key]
+	if !present || v == nil {
+		return def, nil
+	}
+	f, ok := v.(float64)
+	if !ok {
+		if i, isInt := v.(int); isInt {
+			f = float64(i)
+		} else {
+			return 0, fmt.Errorf("%s is a number, not %T", key, v)
+		}
+	}
+	if f != math.Trunc(f) {
+		return 0, fmt.Errorf("%s is a whole number, not %v", key, f)
+	}
+	n := int(f)
+	if n < least || n > most {
+		return 0, fmt.Errorf("%s is %d; it is between %d and %d", key, n, least, most)
+	}
+	return n, nil
+}
+
+// flag is a boolean argument, or def when absent.
+func flag(args map[string]any, key string, def bool) (bool, error) {
+	v, present := args[key]
+	if !present || v == nil {
+		return def, nil
+	}
+	b, ok := v.(bool)
+	if !ok {
+		return false, fmt.Errorf("%s is true or false, not %T", key, v)
+	}
+	return b, nil
+}
+
+// texts is a list-of-strings argument.
+func texts(args map[string]any, key string) ([]string, error) {
+	v, present := args[key]
+	if !present || v == nil {
+		return nil, nil
+	}
+	list, ok := v.([]any)
+	if !ok {
+		if ss, isStrings := v.([]string); isStrings {
+			return ss, nil
+		}
+		return nil, fmt.Errorf("%s is a list of strings, not %T", key, v)
+	}
+	out := make([]string, 0, len(list))
+	for i, item := range list {
+		s, ok := item.(string)
+		if !ok {
+			return nil, fmt.Errorf("%s[%d] is a string, not %T", key, i, item)
+		}
+		out = append(out, s)
+	}
+	return out, nil
+}
+
+// seconds is a timeout argument in seconds, defaulted and bounded below the runtime's call limit.
+func seconds(args map[string]any, key string, def, most int) (time.Duration, error) {
+	n, err := whole(args, key, def, 1, most)
+	return time.Duration(n) * time.Second, err
+}

modules/dunst/cmd/dunst-tools/dunst.go

@@ -0,0 +1,355 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+	"strconv"
+	"strings"
+	"syscall"
+	"time"
+	"unsafe"
+)
+
+var urgencies = []string{"low", "normal", "critical"}
+
+const busTimeout = 10 * time.Second
+
+// Notification is what node-notifier.send shows.
+type Notification struct {
+	Summary   string
+	Body      string
+	Urgency   string
+	AppName   string
+	Icon      string
+	ExpireMS  int
+	Category  string
+	ReplaceID int
+}
+
+func notificationOf(args map[string]any) (Notification, error) {
+	var n Notification
+	var err error
+	if n.Summary, err = text(args, "summary", true); err != nil {
+		return n, err
+	}
+	if n.Body, err = text(args, "body", false); err != nil {
+		return n, err
+	}
+	if n.Urgency, err = text(args, "urgency", false); err != nil {
+		return n, err
+	}
+	if n.Urgency == "" {
+		n.Urgency = "normal"
+	}
+	known := false
+	for _, u := range urgencies {
+		known = known || u == n.Urgency
+	}
+	if !known {
+		return n, fmt.Errorf("urgency %q is low, normal or critical", n.Urgency)
+	}
+	if n.AppName, err = text(args, "app_name", false); err != nil {
+		return n, err
+	}
+	if n.AppName == "" {
+		n.AppName = "mesh"
+	}
+	if n.Icon, err = text(args, "icon", false); err != nil {
+		return n, err
+	}
+	if n.ExpireMS, err = whole(args, "expire_ms", -1, 0, 24*3600*1000); err != nil {
+		return n, err
+	}
+	if n.Category, err = text(args, "category", false); err != nil {
+		return n, err
+	}
+	n.ReplaceID, err = whole(args, "replace_id", 0, 0, 1<<31-1)
+	return n, err
+}
+
+// SendResult is what node-notifier.send answers.
+type SendResult struct {
+	ID int `json:"id"`
+}
+
+// Send shows a notification through the desktop's notification service, whichever runs it.
+func Send(n Notification) (SendResult, error) {
+	s, err := findBus()
+	if err != nil {
+		return SendResult{}, err
+	}
+	args := []string{"--print-id", "--urgency=" + n.Urgency, "--app-name=" + n.AppName}
+	if n.Icon != "" {
+		args = append(args, "--icon="+n.Icon)
+	}
+	if n.ExpireMS >= 0 {
+		args = append(args, "--expire-time="+strconv.Itoa(n.ExpireMS))
+	}
+	if n.Category != "" {
+		args = append(args, "--category="+n.Category)
+	}
+	if n.ReplaceID > 0 {
+		args = append(args, "--replace-id="+strconv.Itoa(n.ReplaceID))
+	}
+	// "--" so a title that starts with a dash is a title.
+	args = append(args, "--", n.Summary)
+	if n.Body != "" {
+		args = append(args, n.Body)
+	}
+	r, err := s.run(busTimeout, "", "notify-send", args...)
+	if err != nil {
+		return SendResult{}, err
+	}
+	if r.Code != 0 {
+		return SendResult{}, fmt.Errorf("notify-send: %s", strings.TrimSpace(r.Stderr))
+	}
+	id, err := strconv.Atoi(strings.TrimSpace(r.Stdout))
+	if err != nil {
+		return SendResult{}, fmt.Errorf("notify-send answered no id: %q", r.Stdout)
+	}
+	return SendResult{ID: id}, nil
+}
+
+// dunstctl runs one dunstctl command over the session bus and answers what it printed.
+func dunstctl(args ...string) (string, error) {
+	s, err := findBus()
+	if err != nil {
+		return "", err
+	}
+	r, err := s.run(busTimeout, "", "dunstctl", args...)
+	if err != nil {
+		return "", err
+	}
+	if r.Code != 0 {
+		return "", fmt.Errorf("dunstctl %s: %s", strings.Join(args, " "), strings.TrimSpace(r.Stderr+r.Stdout))
+	}
+	return r.Stdout, nil
+}
+
+// variantMaps reads busctl's JSON form of an array of dictionaries (aa{sv}), which is how dunstctl
+// answers history and rules, into plain maps.
+func variantMaps(raw string) ([]map[string]any, error) {
+	var doc struct {
+		Type string `json:"type"`
+		Data [][]map[string]struct {
+			Data any `json:"data"`
+		} `json:"data"`
+	}
+	if err := json.Unmarshal([]byte(raw), &doc); err != nil {
+		return nil, fmt.Errorf("dunstctl's answer is not the bus's JSON: %w", err)
+	}
+	if doc.Type != "aa{sv}" {
+		return nil, fmt.Errorf("dunstctl answered %s, not aa{sv}", doc.Type)
+	}
+	out := []map[string]any{}
+	for _, group := range doc.Data {
+		for _, entry := range group {
+			m := map[string]any{}
+			for k, v := range entry {
+				m[k] = v.Data
+			}
+			out = append(out, m)
+		}
+	}
+	return out, nil
+}
+
+// Shown is one notification in the history.
+type Shown struct {
+	ID         int    `json:"id"`
+	AppName    string `json:"app_name"`
+	Summary    string `json:"summary"`
+	Body       string `json:"body,omitempty"`
+	Urgency    string `json:"urgency"`
+	Category   string `json:"category,omitempty"`
+	AgeSeconds int64  `json:"age_seconds"`
+}
+
+// HistoryResult is what node-notifier.history answers.
+type HistoryResult struct {
+	Total         int     `json:"total"`
+	Notifications []Shown `json:"notifications"`
+}
+
+// History is dunst's history, newest first.
+func History(limit int) (HistoryResult, error) {
+	raw, err := dunstctl("history")
+	if err != nil {
+		return HistoryResult{}, err
+	}
+	return parseHistory(raw, monotonicMicros(), limit)
+}
+
+func parseHistory(raw string, nowMicros int64, limit int) (HistoryResult, error) {
+	entries, err := variantMaps(raw)
+	if err != nil {
+		return HistoryResult{}, err
+	}
+	out := HistoryResult{Total: len(entries), Notifications: []Shown{}}
+	type stamped struct {
+		Shown
+		at int64
+	}
+	var all []stamped
+	for _, e := range entries {
+		at := number(e["timestamp"])
+		all = append(all, stamped{Shown{
+			ID: int(number(e["id"])), AppName: str(e["appname"]), Summary: str(e["summary"]), Body: str(e["body"]),
+			Urgency: strings.ToLower(str(e["urgency"])), Category: str(e["category"]),
+			AgeSeconds: max(0, (nowMicros-at)/1_000_000),
+		}, at})
+	}
+	sort.SliceStable(all, func(i, j int) bool { return all[i].at > all[j].at })
+	for i, s := range all {
+		if i == limit {
+			break
+		}
+		out.Notifications = append(out.Notifications, s.Shown)
+	}
+	return out, nil
+}
+
+func number(v any) int64 {
+	switch n := v.(type) {
+	case float64:
+		return int64(n)
+	case json.Number:
+		i, _ := n.Int64()
+		return i
+	}
+	return 0
+}
+
+func str(v any) string {
+	s, _ := v.(string)
+	return s
+}
+
+// monotonicMicros is the clock dunst stamps its notifications with (CLOCK_MONOTONIC, microseconds).
+func monotonicMicros() int64 {
+	var ts syscall.Timespec
+	const clockMonotonic = 1
+	if _, _, errno := syscall.Syscall(syscall.SYS_CLOCK_GETTIME, clockMonotonic, uintptr(unsafe.Pointer(&ts)), 0); errno != 0 {
+		return 0
+	}
+	return ts.Sec*1_000_000 + ts.Nsec/1000
+}
+
+// PauseResult is what dunst_pause and dunst_resume answer.
+type PauseResult struct {
+	Paused bool   `json:"paused"`
+	Note   string `json:"note"`
+}
+
+// SetPaused turns do-not-disturb on or off.
+func SetPaused(on bool) (PauseResult, error) {
+	if _, err := dunstctl("set-paused", strconv.FormatBool(on)); err != nil {
+		return PauseResult{}, err
+	}
+	out, err := dunstctl("is-paused")
+	if err != nil {
+		return PauseResult{}, err
+	}
+	paused := strings.TrimSpace(out) == "true"
+	note := "notifications are shown"
+	if paused {
+		note = "notifications are held back until dunst_resume; the next login starts unpaused"
+	}
+	return PauseResult{Paused: paused, Note: note}, nil
+}
+
+// CloseAll closes what is on screen.
+func CloseAll() (CountResult, error) {
+	if _, err := dunstctl("close-all"); err != nil {
+		return CountResult{}, err
+	}
+	return Count()
+}
+
+// CountResult is what dunst_count answers.
+type CountResult struct {
+	Displayed int  `json:"displayed"`
+	Waiting   int  `json:"waiting"`
+	History   int  `json:"history"`
+	Paused    bool `json:"paused"`
+}
+
+// Count is how many notifications are where.
+func Count() (CountResult, error) {
+	var c CountResult
+	for _, part := range []struct {
+		which string
+		into  *int
+	}{{"displayed", &c.Displayed}, {"waiting", &c.Waiting}, {"history", &c.History}} {
+		out, err := dunstctl("count", part.which)
+		if err != nil {
+			return c, err
+		}
+		n, err := strconv.Atoi(strings.TrimSpace(out))
+		if err != nil {
+			return c, fmt.Errorf("dunstctl count %s answered %q", part.which, out)
+		}
+		*part.into = n
+	}
+	out, err := dunstctl("is-paused")
+	if err != nil {
+		return c, err
+	}
+	c.Paused = strings.TrimSpace(out) == "true"
+	return c, nil
+}
+
+// Rule is one notifier rule in force.
+type Rule struct {
+	Name    string         `json:"name"`
+	Enabled bool           `json:"enabled"`
+	Sets    map[string]any `json:"sets"`
+}
+
+// RulesResult is what dunst_rules answers.
+type RulesResult struct {
+	Files []string `json:"files"`
+	Rules []Rule   `json:"rules"`
+}
+
+// Rules are the rules the running notifier holds, and the files it reads them from.
+func Rules() (RulesResult, error) {
+	raw, err := dunstctl("rules", "--json")
+	if err != nil {
+		return RulesResult{}, err
+	}
+	return parseRules(raw, configFiles(filepath.Join(operatorHome(), ".config", "dunst")))
+}
+
+func parseRules(raw string, files []string) (RulesResult, error) {
+	entries, err := variantMaps(raw)
+	if err != nil {
+		return RulesResult{}, err
+	}
+	out := RulesResult{Files: files, Rules: []Rule{}}
+	for _, e := range entries {
+		r := Rule{Name: str(e["name"]), Enabled: e["enabled"] == true, Sets: map[string]any{}}
+		for k, v := range e {
+			if k != "name" && k != "enabled" {
+				r.Sets[k] = v
+			}
+		}
+		out.Rules = append(out.Rules, r)
+	}
+	sort.SliceStable(out.Rules, func(i, j int) bool { return out.Rules[i].Name < out.Rules[j].Name })
+	return out, nil
+}
+
+// configFiles are dunstrc and its drop-ins in the order dunst reads them.
+func configFiles(dir string) []string {
+	files := []string{}
+	if _, err := os.Stat(filepath.Join(dir, "dunstrc")); err == nil {
+		files = append(files, filepath.Join(dir, "dunstrc"))
+	}
+	dropins, _ := filepath.Glob(filepath.Join(dir, "dunstrc.d", "*.conf"))
+	sort.Strings(dropins)
+	return append(files, dropins...)
+}

modules/dunst/cmd/dunst-tools/dunst_test.go

@@ -0,0 +1,160 @@
+package main
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"reflect"
+	"strconv"
+	"strings"
+	"testing"
+)
+
+// withBus gives the fake machine the account's runtime directory and bus socket.
+func withBus(t *testing.T) string {
+	t.Helper()
+	root := fakeMachine(t)
+	runtime := filepath.Join(runUserDir, strconv.Itoa(os.Getuid()))
+	if err := os.MkdirAll(runtime, 0o700); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(runtime, "bus"), nil, 0o600); err != nil {
+		t.Fatal(err)
+	}
+	return root
+}
+
+// A history as dunstctl answers it (busctl's JSON), two entries out of order.
+const history = `{"type":"aa{sv}","data":[[
+ {"body":{"type":"s","data":"the build is green"},"summary":{"type":"s","data":"CI"},"appname":{"type":"s","data":"mesh"},
+  "category":{"type":"s","data":""},"id":{"type":"i","data":7},"timestamp":{"type":"x","data":100000000},"urgency":{"type":"s","data":"NORMAL"}},
+ {"body":{"type":"s","data":""},"summary":{"type":"s","data":"Battery low"},"appname":{"type":"s","data":"upower"},
+  "category":{"type":"s","data":"device"},"id":{"type":"i","data":9},"timestamp":{"type":"x","data":160000000},"urgency":{"type":"s","data":"CRITICAL"}}
+]]}`
+
+func TestTheHistoryIsNewestFirstWithAgesFromDunstsOwnClock(t *testing.T) {
+	got, err := parseHistory(history, 200_000_000, 20)
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := []Shown{
+		{ID: 9, AppName: "upower", Summary: "Battery low", Urgency: "critical", Category: "device", AgeSeconds: 40},
+		{ID: 7, AppName: "mesh", Summary: "CI", Body: "the build is green", Urgency: "normal", AgeSeconds: 100},
+	}
+	if got.Total != 2 || !reflect.DeepEqual(got.Notifications, want) {
+		t.Fatalf("%+v", got)
+	}
+	if got, _ := parseHistory(history, 200_000_000, 1); len(got.Notifications) != 1 || got.Total != 2 {
+		t.Fatalf("limited: %+v", got)
+	}
+	if _, err := parseHistory(`{"type":"as","data":[]}`, 0, 1); err == nil {
+		t.Fatal("an answer of another type was accepted")
+	}
+	if monotonicMicros() <= 0 {
+		t.Fatal("the monotonic clock")
+	}
+}
+
+func TestSendAsksNotifySendOverTheAccountsBusAndAnswersTheId(t *testing.T) {
+	withBus(t)
+	bin := fakeBinaries(t, map[string]string{"notify-send": `for a in "$@"; do printf '[%s]' "$a"; done > "$LOG"; echo >> "$LOG"; echo "bus=$DBUS_SESSION_BUS_ADDRESS" >> "$LOG"; echo 42`})
+	t.Setenv("LOG", filepath.Join(bin, "log"))
+	n, err := notificationOf(map[string]any{"summary": "-dash title", "body": "hello", "urgency": "critical", "expire_ms": float64(0)})
+	if err != nil {
+		t.Fatal(err)
+	}
+	got, err := Send(n)
+	if err != nil || got.ID != 42 {
+		t.Fatalf("%+v, %v", got, err)
+	}
+	asked, _ := os.ReadFile(filepath.Join(bin, "log"))
+	want := "[--print-id][--urgency=critical][--app-name=mesh][--expire-time=0][--][-dash title][hello]\nbus=unix:path=" +
+		filepath.Join(runUserDir, strconv.Itoa(os.Getuid()), "bus") + "\n"
+	if string(asked) != want {
+		t.Fatalf("notify-send was asked:\n%s\nwant:\n%s", asked, want)
+	}
+}
+
+func TestANotificationIsRefusedForWhatItCannotBe(t *testing.T) {
+	for _, bad := range []map[string]any{{}, {"summary": " "}, {"summary": "x", "urgency": "urgent"}, {"summary": "x", "expire_ms": float64(-5)}} {
+		if _, err := notificationOf(bad); err == nil {
+			t.Errorf("accepted %v", bad)
+		}
+	}
+	n, _ := notificationOf(map[string]any{"summary": "x"})
+	if n.Urgency != "normal" || n.AppName != "mesh" || n.ExpireMS != -1 {
+		t.Fatalf("defaults: %+v", n)
+	}
+}
+
+func TestWithoutABusTheToolsSaySo(t *testing.T) {
+	fakeMachine(t)
+	if _, err := Send(Notification{Summary: "x"}); !errors.Is(err, ErrNoBus) {
+		t.Fatal(err)
+	}
+	if _, err := Count(); !errors.Is(err, ErrNoBus) {
+		t.Fatal(err)
+	}
+}
+
+func TestCountPauseAndCloseAllAreDunstctlsAnswers(t *testing.T) {
+	withBus(t)
+	bin := fakeBinaries(t, map[string]string{"dunstctl": `echo "$*" >> "$LOG"
+case "$*" in
+  "count displayed") echo 1 ;;
+  "count waiting") echo 0 ;;
+  "count history") echo 12 ;;
+  is-paused) cat "$STATE" 2>/dev/null || echo false ;;
+  "set-paused true") echo true > "$STATE" ;;
+  "set-paused false") echo false > "$STATE" ;;
+esac`})
+	t.Setenv("LOG", filepath.Join(bin, "log"))
+	t.Setenv("STATE", filepath.Join(bin, "paused"))
+	c, err := Count()
+	if err != nil || c != (CountResult{Displayed: 1, History: 12}) {
+		t.Fatalf("%+v, %v", c, err)
+	}
+	p, err := SetPaused(true)
+	if err != nil || !p.Paused || !strings.Contains(p.Note, "held back") {
+		t.Fatalf("%+v, %v", p, err)
+	}
+	if c, _ := CloseAll(); !c.Paused {
+		t.Fatalf("close-all answers the counts: %+v", c)
+	}
+	if p, _ := SetPaused(false); p.Paused {
+		t.Fatalf("resumed: %+v", p)
+	}
+	log, _ := os.ReadFile(filepath.Join(bin, "log"))
+	if !strings.Contains(string(log), "close-all\n") {
+		t.Fatalf("dunstctl was asked:\n%s", log)
+	}
+}
+
+func TestRulesAreTheRunningNotifiersWithTheFilesTheyComeFrom(t *testing.T) {
+	root := t.TempDir()
+	for _, f := range []string{"dunstrc", "dunstrc.d/50-slack.conf", "dunstrc.d/10-mail.conf", "dunstrc.d/notes.txt"} {
+		if err := os.MkdirAll(filepath.Dir(filepath.Join(root, f)), 0o755); err != nil {
+			t.Fatal(err)
+		}
+		if err := os.WriteFile(filepath.Join(root, f), nil, 0o644); err != nil {
+			t.Fatal(err)
+		}
+	}
+	raw := `{"type":"aa{sv}","data":[[{"enabled":{"type":"b","data":true},"appname":{"type":"s","data":"Slack"},
+	  "fc":{"type":"s","data":"#6715ebff"},"name":{"type":"s","data":"slack"},"timeout":{"type":"x","data":10000000}}]]}`
+	got, err := parseRules(raw, configFiles(root))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(got.Rules) != 1 || got.Rules[0].Name != "slack" || !got.Rules[0].Enabled || got.Rules[0].Sets["appname"] != "Slack" {
+		t.Fatalf("%+v", got)
+	}
+	var names []string
+	for _, f := range got.Files {
+		rel, _ := filepath.Rel(root, f)
+		names = append(names, rel)
+	}
+	if !reflect.DeepEqual(names, []string{"dunstrc", "dunstrc.d/10-mail.conf", "dunstrc.d/50-slack.conf"}) {
+		t.Fatalf("files: %v", names)
+	}
+}

modules/dunst/cmd/dunst-tools/main.go

@@ -0,0 +1,91 @@
+// dunst's Go tools bundle (novox/hq ADR 0188, ADR 0193, ADR 0208): its implementation of
+// node-notifier's verbs `send` and `history`, and its own tools, served by the node's runtime as the
+// operator account. Everything here goes over the account's session bus; none of it needs the screen.
+package main
+
+import (
+	"fmt"
+	"os"
+
+	stdio "git.novox.be/novox/mesh-sdk/go"
+)
+
+func main() {
+	if err := stdio.Serve("", tools()); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
+
+func tools() []stdio.Tool {
+	return []stdio.Tool{
+		{
+			Name: "node-notifier.send",
+			Description: "Show a notification on the operator's desktop: a title, a body, an urgency (low, " +
+				"normal, critical), and optionally the sending application's name, an icon and how long it stays. " +
+				"Answers the notification's id.",
+			Input: map[string]any{
+				"type": "object",
+				"properties": map[string]any{
+					"summary":    map[string]any{"type": "string", "description": "the title"},
+					"body":       map[string]any{"type": "string", "description": "the text; simple markup (<b>, <i>, <u>, <a href>) is shown"},
+					"urgency":    map[string]any{"type": "string", "enum": urgencies, "description": "default normal"},
+					"app_name":   map[string]any{"type": "string", "description": "who it is from (default: mesh); a notifier rule can match it"},
+					"icon":       map[string]any{"type": "string", "description": "an icon name from the icon theme, or a file"},
+					"expire_ms":  map[string]any{"type": "integer", "description": "how long it stays; 0 until dismissed (default: the urgency's own)"},
+					"category":   map[string]any{"type": "string", "description": "a notification category, e.g. email.arrived"},
+					"replace_id": map[string]any{"type": "integer", "description": "replace the notification with this id instead of adding one"},
+				},
+				"required": []string{"summary"},
+			},
+			Run: func(args map[string]any) (any, error) {
+				n, err := notificationOf(args)
+				if err != nil {
+					return nil, err
+				}
+				return Send(n)
+			},
+		},
+		{
+			Name: "node-notifier.history",
+			Description: "The notifications the operator was shown, newest first: id, application, title, " +
+				"body, urgency and how long ago.",
+			Input: map[string]any{
+				"limit": map[string]any{"type": "integer", "description": "at most this many (default 20, at most 200)"},
+			},
+			Run: func(args map[string]any) (any, error) {
+				limit, err := whole(args, "limit", 20, 1, 200)
+				if err != nil {
+					return nil, err
+				}
+				return History(limit)
+			},
+		},
+		{
+			Name:        "dunst_pause",
+			Description: "Do not disturb: hold every new notification back until resumed. They are shown then, not lost.",
+			Run:         func(map[string]any) (any, error) { return SetPaused(true) },
+		},
+		{
+			Name:        "dunst_resume",
+			Description: "End do-not-disturb: notifications held back are shown.",
+			Run:         func(map[string]any) (any, error) { return SetPaused(false) },
+		},
+		{
+			Name:        "dunst_close_all",
+			Description: "Close every notification on screen. They stay in the history.",
+			Run:         func(map[string]any) (any, error) { return CloseAll() },
+		},
+		{
+			Name: "dunst_rules",
+			Description: "The notifier's rules in force — each rule's name, whether it is enabled, what it " +
+				"matches and what it sets — and the files they come from (the mesh's dunstrc, then dunstrc.d).",
+			Run: func(map[string]any) (any, error) { return Rules() },
+		},
+		{
+			Name:        "dunst_count",
+			Description: "How many notifications are shown, waiting and in the history, and whether do-not-disturb is on.",
+			Run:         func(map[string]any) (any, error) { return Count() },
+		},
+	}
+}

modules/dunst/cmd/dunst-tools/manifest_helpers_test.go

@@ -0,0 +1,175 @@
+package main
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+// The module's manifest, read the way the catalogue reads it, for the manifest tests. The same in
+// every desktop module that carries it.
+
+type manifest struct {
+	Module       string           `json:"module"`
+	Version      string           `json:"version"`
+	Capabilities []string         `json:"capabilities"`
+	Requires     []string         `json:"requires"`
+	Claims       []claim          `json:"claims"`
+	Seats        []any            `json:"seats"`
+	Tools        []string         `json:"tools"`
+	Environment  *environment     `json:"environment"`
+	Shell        []shellCode      `json:"shell"`
+	Resources    []map[string]any `json:"resources"`
+	Build        struct {
+		Artifacts []map[string]any `json:"artifacts"`
+	} `json:"build"`
+}
+
+type claim struct {
+	Name   string   `json:"name"`
+	Scope  string   `json:"scope"`
+	Serves []string `json:"serves"`
+}
+
+type environment struct {
+	Variables map[string]string `json:"variables"`
+	Path      []map[string]any  `json:"path"`
+}
+
+type shellCode struct {
+	For  string `json:"for"`
+	Slot string `json:"slot"`
+	Code string `json:"code"`
+}
+
+func readManifest(t *testing.T) manifest {
+	t.Helper()
+	raw, err := os.ReadFile(filepath.Join("..", "..", "module.json"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	dec := json.NewDecoder(strings.NewReader(string(raw)))
+	dec.DisallowUnknownFields()
+	var m manifest
+	if err := dec.Decode(&m); err != nil {
+		t.Fatalf("module.json: %v", err)
+	}
+	return m
+}
+
+func (m manifest) resource(t *testing.T, id string) map[string]any {
+	t.Helper()
+	for _, r := range m.Resources {
+		if r["id"] == id {
+			return r
+		}
+	}
+	t.Fatalf("no resource %q", id)
+	return nil
+}
+
+func (m manifest) packages() (present, absent []string) {
+	for _, r := range m.Resources {
+		if r["type"] == "package" {
+			if r["absent"] == true {
+				absent = append(absent, r["package"].(string))
+			} else {
+				present = append(present, r["package"].(string))
+			}
+		}
+	}
+	return present, absent
+}
+
+// sameAsSource checks that a file resource's content is byte for byte the module's source file, so
+// the readable file in the repository is what the machine gets.
+func (m manifest) sameAsSource(t *testing.T, id, source string) {
+	t.Helper()
+	want, err := os.ReadFile(filepath.Join("..", "..", source))
+	if err != nil {
+		t.Fatal(err)
+	}
+	r := m.resource(t, id)
+	if r["type"] != "file" {
+		t.Fatalf("%s is a %v, not a file", id, r["type"])
+	}
+	if got, _ := r["content"].(string); got != string(want) {
+		t.Fatalf("resource %s's content is not %s: edit the source and copy it into module.json", id, source)
+	}
+	if r["owner"] != "${machine:account}" && !strings.HasPrefix(r["path"].(string), "/etc/") {
+		t.Fatalf("%s under the home is the account's", id)
+	}
+}
+
+// checkTheToolsAgree checks that the manifest lists the module's own tools exactly, that the bundle
+// serves each seat verb the claims promise as <seat>.<verb>, and that the Go bundle is declared.
+func checkTheToolsAgree(t *testing.T, m manifest) {
+	t.Helper()
+	own, seat := map[string]bool{}, map[string]bool{}
+	for _, tool := range tools() {
+		if strings.Contains(tool.Name, ".") {
+			seat[tool.Name] = true
+		} else {
+			own[tool.Name] = true
+		}
+		if strings.TrimSpace(tool.Description) == "" {
+			t.Errorf("%s has no description", tool.Name)
+		}
+	}
+	listed := map[string]bool{}
+	for _, name := range m.Tools {
+		listed[name] = true
+		if !own[name] {
+			t.Errorf("module.json lists %s, which the bundle does not serve", name)
+		}
+	}
+	for name := range own {
+		if !listed[name] {
+			t.Errorf("the bundle serves %s, which module.json does not list", name)
+		}
+		if !strings.HasPrefix(name, strings.ReplaceAll(m.Module, "-", "_")+"_") {
+			t.Errorf("%s is not prefixed with the module's name", name)
+		}
+	}
+	promised := map[string]bool{}
+	for _, c := range m.Claims {
+		for _, verb := range c.Serves {
+			promised[c.Name+"."+verb] = true
+			if !seat[c.Name+"."+verb] {
+				t.Errorf("the claim on %s promises %s, which the bundle does not serve", c.Name, verb)
+			}
+		}
+	}
+	for name := range seat {
+		if !promised[name] {
+			t.Errorf("the bundle serves %s, which no claim promises", name)
+		}
+	}
+	var bundle map[string]any
+	for _, a := range m.Build.Artifacts {
+		if a["kind"] == "bundle" {
+			bundle = a
+		}
+	}
+	if bundle == nil || bundle["language"] != "go" || bundle["system"] != "arch" ||
+		bundle["from"] != "cmd/"+m.Module+"-tools" || bundle["binary"] != m.Module+"-tools" {
+		t.Errorf("the Go tools bundle: %v", bundle)
+	}
+}
+
+// checkNoSecretsOrInstallationNames refuses what a catalogue manifest must never carry.
+func checkNoSecretsOrInstallationNames(t *testing.T) {
+	t.Helper()
+	raw, err := os.ReadFile(filepath.Join("..", "..", "module.json"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	s := strings.ToLower(string(raw))
+	for _, never := range []string{"/home/", "jochen", "g14", "shanks", "novox.be", "api_key", ".hal/", "greenclip daemon"} {
+		if strings.Contains(s, never) {
+			t.Errorf("module.json names %q", never)
+		}
+	}
+}

modules/dunst/cmd/dunst-tools/manifest_test.go

@@ -0,0 +1,77 @@
+package main
+
+import (
+	"reflect"
+	"strings"
+	"testing"
+)
+
+// dunst's shape (novox/hq ADR 0208): it claims node-notifier serving send and history, owns its
+// dunstrc and the drop-in directory other modules' rules go in, and starts nothing — D-Bus starts it
+// on the first notification. It draws only once a notification arrives, through the bus's
+// activation, so it requires no display of its own.
+
+func TestItClaimsTheNotifierSeatServingSendAndHistory(t *testing.T) {
+	m := readManifest(t)
+	if m.Module != "dunst" || m.Seats != nil {
+		t.Fatalf("module %q declares seats %v", m.Module, m.Seats)
+	}
+	if !reflect.DeepEqual(m.Claims, []claim{{Name: "node-notifier", Scope: "node", Serves: []string{"send", "history"}}}) {
+		t.Fatalf("claims: %+v", m.Claims)
+	}
+	if present, absent := m.packages(); !reflect.DeepEqual(present, []string{"dunst", "libnotify"}) || absent != nil {
+		t.Fatalf("packages: %v, absent %v", present, absent)
+	}
+}
+
+func TestItOwnsItsFileAndTheDropInDirectory(t *testing.T) {
+	m := readManifest(t)
+	m.sameAsSource(t, "configuration", "files/dunstrc")
+	if p := m.resource(t, "configuration")["path"]; p != "${machine:account-home}/.config/dunst/dunstrc" {
+		t.Fatalf("path: %v", p)
+	}
+	if d := m.resource(t, "dropins"); d["type"] != "directory" || d["path"] != "${machine:account-home}/.config/dunst/dunstrc.d" {
+		t.Fatalf("drop-ins: %v", d)
+	}
+	for _, r := range m.Resources {
+		if p, _ := r["path"].(string); strings.Contains(p, "dunstrc.d/") {
+			t.Fatalf("a rule of another module's: %v", r)
+		}
+	}
+}
+
+func TestTheFileIsTheDecidedOneAndCallsTheSeatsMenu(t *testing.T) {
+	m := readManifest(t)
+	c := m.resource(t, "configuration")["content"].(string)
+	for _, want := range []string{"origin = top-right", "transparency = 0", "corner_radius = 0", "font = Inter 10", "dmenu = dmenu -p dunst"} {
+		if !strings.Contains(c, "    "+want+"\n") {
+			t.Errorf("lacks %q", want)
+		}
+	}
+	for _, never := range []string{"/usr/bin/dmenu", "Hack", "icon_path", "/home/"} {
+		if strings.Contains(c, never) {
+			t.Errorf("names %q", never)
+		}
+	}
+}
+
+func TestNothingStartsItButTheBus(t *testing.T) {
+	m := readManifest(t)
+	if m.Shell != nil {
+		t.Fatalf("a session start: %+v", m.Shell)
+	}
+	for _, r := range m.Resources {
+		if r["type"] == "service" || r["type"] == "process" {
+			t.Fatalf("a unit: %v", r)
+		}
+		if p, _ := r["path"].(string); strings.Contains(p, "autostart") || strings.Contains(p, "i3/config.d") {
+			t.Fatalf("a start: %v", r)
+		}
+	}
+}
+
+func TestTheToolsAgreeWithTheManifest(t *testing.T) {
+	m := readManifest(t)
+	checkTheToolsAgree(t, m)
+	checkNoSecretsOrInstallationNames(t)
+}

modules/dunst/cmd/dunst-tools/session.go

@@ -0,0 +1,423 @@
+// The operator's graphical session, as a tool the node's runtime runs finds it (novox/hq ADR 0208).
+//
+// The runtime is a system service running as the operator account (ADR 0175): it has the account's
+// uid and none of the session's environment — no DISPLAY, no XAUTHORITY, no session bus. A tool that
+// draws on the screen or talks to the desktop's D-Bus must find them. It reads them from a process of
+// the account that is part of the session (the window manager first), the same thing `loginctl` and
+// a person's own shell would point at, and says where it found them.
+//
+// Long-lived programs a tool starts go to the account's own service manager through `systemd-run
+// --user`, never as children of the tool: the runtime's unit is a cgroup the service manager empties
+// whenever the runtime restarts, and a compositor or a clipboard owner started from inside it would
+// die with it.
+//
+// This file is the same in every desktop module that carries it; it moves into the Go SDK once a
+// second consumer outside the desktop wants it.
+package main
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"sort"
+	"strconv"
+	"strings"
+	"syscall"
+	"time"
+)
+
+// Where the session is looked for. Variables so a test can point them at a fake tree.
+var (
+	procRoot   = "/proc"
+	runUserDir = "/run/user"
+	x11Sockets = "/tmp/.X11-unix"
+)
+
+// sessionHolders are the processes whose environment is the session's, best first: the window
+// manager is the session, the rest are its children. Anything else carrying DISPLAY ranks after them.
+var sessionHolders = []string{"i3", "sway", "i3bar", "picom", "xss-lock", "dunst", "clipmenud", "xterm"}
+
+// sessionKeys are the variables a session carries that a tool hands on to what it runs.
+var sessionKeys = []string{"DISPLAY", "XAUTHORITY", "WAYLAND_DISPLAY", "DBUS_SESSION_BUS_ADDRESS",
+	"XDG_RUNTIME_DIR", "XDG_SESSION_ID", "I3SOCK"}
+
+// Session is what a tool needs to reach the operator's desktop.
+type Session struct {
+	UID        int    `json:"uid"`
+	Display    string `json:"display,omitempty"`
+	XAuthority string `json:"xauthority,omitempty"`
+	Wayland    string `json:"wayland_display,omitempty"`
+	Bus        string `json:"bus,omitempty"`
+	RuntimeDir string `json:"runtime_dir,omitempty"`
+	SessionID  string `json:"session_id,omitempty"`
+	I3Sock     string `json:"i3sock,omitempty"`
+	// From says where the values were found: the tool's own environment, a process, or the socket.
+	From string `json:"from"`
+}
+
+// ErrNoSession is answered by a tool that needs the desktop when nobody is logged in to it.
+var ErrNoSession = errors.New("no graphical session")
+
+// ErrTimedOut is what run answers for a command ended because it ran past its time.
+var ErrTimedOut = errors.New("timed out")
+
+// ErrNoBus is answered by a tool that needs the session bus when the account has none.
+var ErrNoBus = errors.New("no session bus")
+
+// operatorHome is the account's home: what the runtime was told, else the process's own.
+func operatorHome() string {
+	if h := strings.TrimSpace(os.Getenv("MESH_OPERATOR_HOME")); h != "" {
+		return h
+	}
+	h, _ := os.UserHomeDir()
+	return h
+}
+
+// findSession finds the graphical session of the account this tool runs as, or answers
+// ErrNoSession with what it looked at.
+func findSession() (Session, error) {
+	s := findEnvironment()
+	if s.Display == "" && s.Wayland == "" {
+		return s, fmt.Errorf("%w for uid %d on this machine: no process of the account carries DISPLAY "+
+			"or WAYLAND_DISPLAY, and no X server socket in %s has an authority file to go with it. "+
+			"Is anyone logged in to the desktop?", ErrNoSession, s.UID, x11Sockets)
+	}
+	return s, nil
+}
+
+// findBus finds the account's session bus, which a logged-in account has whether or not a desktop
+// is running.
+func findBus() (Session, error) {
+	s := findEnvironment()
+	if s.Bus == "" {
+		return s, fmt.Errorf("%w for uid %d: DBUS_SESSION_BUS_ADDRESS is not set and %s does not exist "+
+			"(the account is not logged in)", ErrNoBus, s.UID, filepath.Join(runUserDir, strconv.Itoa(s.UID), "bus"))
+	}
+	return s, nil
+}
+
+func findEnvironment() Session {
+	uid := os.Getuid()
+	s := Session{UID: uid}
+	own := map[string]string{}
+	for _, k := range sessionKeys {
+		own[k] = os.Getenv(k)
+	}
+	if own["DISPLAY"] != "" || own["WAYLAND_DISPLAY"] != "" {
+		s.fill(own)
+		s.From = "the tool's own environment"
+	} else if pid, comm, env, ok := sessionProcess(uid); ok {
+		s.fill(env)
+		s.From = fmt.Sprintf("process %s (pid %d)", comm, pid)
+	} else if display, ok := lonelyX11Socket(); ok {
+		if a := filepath.Join(operatorHome(), ".Xauthority"); exists(a) {
+			s.Display, s.XAuthority = display, a
+			s.From = "the X server socket and the account's ~/.Xauthority"
+		}
+		s.fill(own)
+	} else {
+		s.fill(own)
+		s.From = "nothing: no session found"
+	}
+	// The bus and the runtime directory are the account's, whether or not the process named them.
+	runtime := filepath.Join(runUserDir, strconv.Itoa(uid))
+	if s.RuntimeDir == "" && exists(runtime) {
+		s.RuntimeDir = runtime
+	}
+	if s.Bus == "" && s.RuntimeDir != "" && exists(filepath.Join(s.RuntimeDir, "bus")) {
+		s.Bus = "unix:path=" + filepath.Join(s.RuntimeDir, "bus")
+	}
+	return s
+}
+
+func (s *Session) fill(env map[string]string) {
+	set := func(dst *string, key string) {
+		if *dst == "" {
+			*dst = env[key]
+		}
+	}
+	set(&s.Display, "DISPLAY")
+	set(&s.XAuthority, "XAUTHORITY")
+	set(&s.Wayland, "WAYLAND_DISPLAY")
+	set(&s.Bus, "DBUS_SESSION_BUS_ADDRESS")
+	set(&s.RuntimeDir, "XDG_RUNTIME_DIR")
+	set(&s.SessionID, "XDG_SESSION_ID")
+	set(&s.I3Sock, "I3SOCK")
+}
+
+// sessionProcess is the best process of this uid whose environment names a display.
+func sessionProcess(uid int) (int, string, map[string]string, bool) {
+	entries, err := os.ReadDir(procRoot)
+	if err != nil {
+		return 0, "", nil, false
+	}
+	type candidate struct {
+		pid  int
+		comm string
+		env  map[string]string
+		rank int
+	}
+	var found []candidate
+	for _, e := range entries {
+		pid, err := strconv.Atoi(e.Name())
+		if err != nil {
+			continue
+		}
+		dir := filepath.Join(procRoot, e.Name())
+		if owner, ok := ownerOf(dir); !ok || owner != uid {
+			continue
+		}
+		raw, err := os.ReadFile(filepath.Join(dir, "environ"))
+		if err != nil {
+			continue
+		}
+		env := parseEnviron(raw)
+		if env["DISPLAY"] == "" && env["WAYLAND_DISPLAY"] == "" {
+			continue
+		}
+		comm := readTrimmed(filepath.Join(dir, "comm"))
+		rank := len(sessionHolders)
+		for i, h := range sessionHolders {
+			if h == comm {
+				rank = i
+				break
+			}
+		}
+		found = append(found, candidate{pid, comm, env, rank})
+	}
+	if len(found) == 0 {
+		return 0, "", nil, false
+	}
+	sort.Slice(found, func(i, j int) bool {
+		if found[i].rank != found[j].rank {
+			return found[i].rank < found[j].rank
+		}
+		return found[i].pid > found[j].pid // the newer of two equals
+	})
+	best := found[0]
+	return best.pid, best.comm, best.env, true
+}
+
+func parseEnviron(raw []byte) map[string]string {
+	env := map[string]string{}
+	for _, kv := range bytes.Split(raw, []byte{0}) {
+		if i := bytes.IndexByte(kv, '='); i > 0 {
+			env[string(kv[:i])] = string(kv[i+1:])
+		}
+	}
+	return env
+}
+
+func ownerOf(path string) (int, bool) {
+	info, err := os.Stat(path)
+	if err != nil {
+		return 0, false
+	}
+	st, ok := info.Sys().(*syscall.Stat_t)
+	if !ok {
+		return 0, false
+	}
+	return int(st.Uid), true
+}
+
+// lonelyX11Socket is the display of the one X server socket there is, when there is exactly one.
+func lonelyX11Socket() (string, bool) {
+	entries, err := os.ReadDir(x11Sockets)
+	if err != nil {
+		return "", false
+	}
+	var displays []string
+	for _, e := range entries {
+		if n := strings.TrimPrefix(e.Name(), "X"); n != e.Name() {
+			if _, err := strconv.Atoi(n); err == nil {
+				displays = append(displays, ":"+n)
+			}
+		}
+	}
+	if len(displays) != 1 {
+		return "", false
+	}
+	return displays[0], true
+}
+
+func readTrimmed(path string) string {
+	b, err := os.ReadFile(path)
+	if err != nil {
+		return ""
+	}
+	return strings.TrimSpace(string(b))
+}
+
+func exists(path string) bool {
+	_, err := os.Stat(path)
+	return err == nil
+}
+
+// Env is this process's environment with the session's variables in place of its own.
+func (s Session) Env() []string {
+	drop := map[string]bool{}
+	for _, k := range sessionKeys {
+		drop[k] = true
+	}
+	var env []string
+	for _, kv := range os.Environ() {
+		if i := strings.IndexByte(kv, '='); i > 0 && drop[kv[:i]] {
+			continue
+		}
+		env = append(env, kv)
+	}
+	add := func(k, v string) {
+		if v != "" {
+			env = append(env, k+"="+v)
+		}
+	}
+	add("DISPLAY", s.Display)
+	add("XAUTHORITY", s.XAuthority)
+	add("WAYLAND_DISPLAY", s.Wayland)
+	add("DBUS_SESSION_BUS_ADDRESS", s.Bus)
+	add("XDG_RUNTIME_DIR", s.RuntimeDir)
+	add("XDG_SESSION_ID", s.SessionID)
+	add("I3SOCK", s.I3Sock)
+	return env
+}
+
+// mostOutput bounds what a command may answer with, per stream.
+const mostOutput = 256 << 10
+
+// Result is what a command did.
+type Result struct {
+	Stdout    string `json:"stdout"`
+	Stderr    string `json:"stderr,omitempty"`
+	Code      int    `json:"code"`
+	Truncated bool   `json:"truncated,omitempty"`
+}
+
+// run runs a command in the session's environment, its input given, ended with everything it
+// started after timeout. A command that is not installed is an error naming it; one that exits
+// non-zero is a Result with its code, for the caller to judge.
+func (s Session) run(timeout time.Duration, stdin string, name string, args ...string) (Result, error) {
+	path, err := exec.LookPath(name)
+	if err != nil {
+		return Result{}, fmt.Errorf("%s is not installed on this machine", name)
+	}
+	cmd := exec.Command(path, args...)
+	cmd.Env = s.Env()
+	if home := operatorHome(); exists(home) {
+		cmd.Dir = home
+	}
+	if stdin != "" {
+		cmd.Stdin = strings.NewReader(stdin)
+	}
+	var out, errOut capped
+	cmd.Stdout, cmd.Stderr = &out, &errOut
+	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+	if err := cmd.Start(); err != nil {
+		return Result{}, fmt.Errorf("%s: %w", name, err)
+	}
+	done := make(chan error, 1)
+	go func() { done <- cmd.Wait() }()
+	select {
+	case err = <-done:
+	case <-time.After(timeout):
+		_ = syscall.Kill(-cmd.Process.Pid, syscall.SIGKILL)
+		<-done
+		return Result{Stdout: out.String(), Stderr: errOut.String()},
+			fmt.Errorf("%s did not finish within %s and was ended: %w", name, timeout, ErrTimedOut)
+	}
+	r := Result{Stdout: out.String(), Stderr: errOut.String(), Truncated: out.cut || errOut.cut}
+	var exit *exec.ExitError
+	if errors.As(err, &exit) {
+		r.Code = exit.ExitCode()
+	} else if err != nil {
+		return r, fmt.Errorf("%s: %w", name, err)
+	}
+	return r, nil
+}
+
+// detach starts a long-lived program under the account's own service manager, as a transient unit
+// that carries the session's display, so it outlives the runtime that asked for it. A unit already
+// running under the same name is stopped first, so a fixed name means "at most one".
+func (s Session) detach(unit string, args ...string) error {
+	if s.RuntimeDir == "" {
+		return fmt.Errorf("%w: the account's runtime directory is missing, so its service manager "+
+			"cannot be reached", ErrNoBus)
+	}
+	_, _ = s.run(5*time.Second, "", "systemctl", "--user", "stop", unit+".service")
+	call := []string{"--user", "--collect", "--quiet", "--unit=" + unit}
+	for _, kv := range [][2]string{{"DISPLAY", s.Display}, {"XAUTHORITY", s.XAuthority},
+		{"WAYLAND_DISPLAY", s.Wayland}, {"XDG_SESSION_ID", s.SessionID}, {"I3SOCK", s.I3Sock}} {
+		if kv[1] != "" {
+			call = append(call, "--setenv="+kv[0]+"="+kv[1])
+		}
+	}
+	call = append(call, "--")
+	call = append(call, args...)
+	r, err := s.run(10*time.Second, "", "systemd-run", call...)
+	if err != nil {
+		return err
+	}
+	if r.Code != 0 {
+		return fmt.Errorf("systemd-run %s: %s", unit, strings.TrimSpace(r.Stderr))
+	}
+	return nil
+}
+
+// uniqueUnit is a transient unit name that will not collide with an earlier one.
+func uniqueUnit(prefix string) string {
+	return fmt.Sprintf("%s-%d", prefix, time.Now().UnixNano())
+}
+
+type capped struct {
+	bytes.Buffer
+	cut bool
+}
+
+func (c *capped) Write(p []byte) (int, error) {
+	if room := mostOutput - c.Len(); room < len(p) {
+		if room > 0 {
+			c.Buffer.Write(p[:room])
+		}
+		c.cut = true
+		return len(p), nil
+	}
+	return c.Buffer.Write(p)
+}
+
+// processesOf are the pids of this uid's processes whose command name is comm, oldest first.
+func processesOf(comm string) []int {
+	entries, err := os.ReadDir(procRoot)
+	if err != nil {
+		return nil
+	}
+	uid := os.Getuid()
+	var pids []int
+	for _, e := range entries {
+		pid, err := strconv.Atoi(e.Name())
+		if err != nil {
+			continue
+		}
+		dir := filepath.Join(procRoot, e.Name())
+		if owner, ok := ownerOf(dir); !ok || owner != uid {
+			continue
+		}
+		if readTrimmed(filepath.Join(dir, "comm")) == comm {
+			pids = append(pids, pid)
+		}
+	}
+	sort.Ints(pids)
+	return pids
+}
+
+// signalAll sends sig to every process of this uid named comm, and answers the pids it reached.
+func signalAll(comm string, sig syscall.Signal) []int {
+	var reached []int
+	for _, pid := range processesOf(comm) {
+		if syscall.Kill(pid, sig) == nil {
+			reached = append(reached, pid)
+		}
+	}
+	return reached
+}

modules/dunst/cmd/dunst-tools/session_test.go

@@ -0,0 +1,174 @@
+package main
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"testing"
+	"time"
+)
+
+// fakeMachine points the session finder at a temporary /proc, /run/user and X socket directory, with
+// none of the test process's own session variables, and gives back the root.
+func fakeMachine(t *testing.T) string {
+	t.Helper()
+	root := t.TempDir()
+	procRoot, runUserDir, x11Sockets = filepath.Join(root, "proc"), filepath.Join(root, "run-user"), filepath.Join(root, "x11")
+	for _, d := range []string{procRoot, runUserDir, x11Sockets} {
+		if err := os.MkdirAll(d, 0o755); err != nil {
+			t.Fatal(err)
+		}
+	}
+	for _, k := range sessionKeys {
+		t.Setenv(k, "")
+	}
+	t.Setenv("MESH_OPERATOR_HOME", filepath.Join(root, "home"))
+	t.Cleanup(func() { procRoot, runUserDir, x11Sockets = "/proc", "/run/user", "/tmp/.X11-unix" })
+	return root
+}
+
+func fakeProcess(t *testing.T, pid int, comm string, env ...string) {
+	t.Helper()
+	dir := filepath.Join(procRoot, strconv.Itoa(pid))
+	if err := os.MkdirAll(dir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(dir, "comm"), []byte(comm+"\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(dir, "environ"), []byte(strings.Join(env, "\x00")+"\x00"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestTheSessionIsReadFromTheWindowManagerBeforeAnyOtherProcess(t *testing.T) {
+	fakeMachine(t)
+	fakeProcess(t, 900, "xterm", "DISPLAY=:9", "XAUTHORITY=/elsewhere")
+	fakeProcess(t, 100, "i3", "DISPLAY=:1", "XAUTHORITY=/home/op/.Xauthority",
+		"DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus", "XDG_SESSION_ID=3", "SECRET_TOKEN=never-copied")
+	fakeProcess(t, 50, "bash", "PATH=/usr/bin")
+	s, err := findSession()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if s.Display != ":1" || s.XAuthority != "/home/op/.Xauthority" || s.SessionID != "3" || !strings.Contains(s.From, "i3 (pid 100)") {
+		t.Fatalf("the window manager's environment: %+v", s)
+	}
+	for _, kv := range s.Env() {
+		if strings.HasPrefix(kv, "SECRET_TOKEN=") {
+			t.Fatal("a variable of the session process that is not a session variable was handed on")
+		}
+	}
+}
+
+func TestAnyProcessCarryingADisplayServesWhenTheWindowManagerIsNotFound(t *testing.T) {
+	fakeMachine(t)
+	fakeProcess(t, 10, "firefox", "DISPLAY=:0")
+	fakeProcess(t, 20, "firefox", "DISPLAY=:2")
+	s, err := findSession()
+	if err != nil || s.Display != ":2" {
+		t.Fatalf("the newest of two equals: %+v, %v", s, err)
+	}
+}
+
+func TestNoSessionIsAClearAnswerNotAGuess(t *testing.T) {
+	fakeMachine(t)
+	fakeProcess(t, 10, "sshd", "PATH=/usr/bin")
+	_, err := findSession()
+	if !errors.Is(err, ErrNoSession) || !strings.Contains(err.Error(), "logged in to the desktop") {
+		t.Fatalf("no session: %v", err)
+	}
+}
+
+func TestOneXSocketAndTheAccountsAuthorityFileAreASession(t *testing.T) {
+	root := fakeMachine(t)
+	if err := os.WriteFile(filepath.Join(x11Sockets, "X0"), nil, 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.MkdirAll(filepath.Join(root, "home"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(root, "home", ".Xauthority"), nil, 0o600); err != nil {
+		t.Fatal(err)
+	}
+	s, err := findSession()
+	if err != nil || s.Display != ":0" || !strings.HasSuffix(s.XAuthority, "/home/.Xauthority") {
+		t.Fatalf("socket and authority: %+v, %v", s, err)
+	}
+}
+
+func TestTheBusIsTheAccountsRuntimeDirectoryWhenNoProcessNamesIt(t *testing.T) {
+	fakeMachine(t)
+	runtime := filepath.Join(runUserDir, strconv.Itoa(os.Getuid()))
+	if _, err := findBus(); !errors.Is(err, ErrNoBus) {
+		t.Fatalf("no runtime directory is no bus: %v", err)
+	}
+	if err := os.MkdirAll(runtime, 0o700); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(runtime, "bus"), nil, 0o600); err != nil {
+		t.Fatal(err)
+	}
+	s, err := findBus()
+	if err != nil || s.Bus != "unix:path="+filepath.Join(runtime, "bus") || s.RuntimeDir != runtime {
+		t.Fatalf("bus: %+v, %v", s, err)
+	}
+	env := strings.Join(s.Env(), "\n")
+	if !strings.Contains(env, "XDG_RUNTIME_DIR="+runtime) || !strings.Contains(env, "DBUS_SESSION_BUS_ADDRESS=unix:path=") {
+		t.Fatalf("the bus is handed on: %s", env)
+	}
+}
+
+func TestACommandIsBoundedAndANonZeroExitIsAResult(t *testing.T) {
+	fakeMachine(t)
+	s := Session{}
+	r, err := s.run(5*time.Second, "in", "sh", "-c", "cat; echo err >&2; exit 3")
+	if err != nil || r.Stdout != "in" || r.Code != 3 || strings.TrimSpace(r.Stderr) != "err" {
+		t.Fatalf("result: %+v, %v", r, err)
+	}
+	start := time.Now()
+	if _, err := s.run(200*time.Millisecond, "", "sh", "-c", "sleep 30 & sleep 30"); err == nil || time.Since(start) > 5*time.Second {
+		t.Fatalf("a command past its time is ended with what it started: %v after %s", err, time.Since(start))
+	}
+	if _, err := s.run(time.Second, "", "no-such-program-here"); err == nil || !strings.Contains(err.Error(), "not installed") {
+		t.Fatalf("a missing program: %v", err)
+	}
+}
+
+func TestDetachAsksTheAccountsServiceManagerWithTheSessionsDisplay(t *testing.T) {
+	fakeMachine(t)
+	bin := fakeBinaries(t, map[string]string{
+		"systemctl":   `echo "systemctl $*" >> "$LOG"`,
+		"systemd-run": `echo "systemd-run $*" >> "$LOG"`,
+	})
+	log := filepath.Join(bin, "log")
+	t.Setenv("LOG", log)
+	s := Session{Display: ":1", XAuthority: "/x", RuntimeDir: "/run/user/1"}
+	if err := s.detach("picom-session", "picom", "--config", "/c"); err != nil {
+		t.Fatal(err)
+	}
+	got, _ := os.ReadFile(log)
+	want := "systemctl --user stop picom-session.service\n" +
+		"systemd-run --user --collect --quiet --unit=picom-session --setenv=DISPLAY=:1 --setenv=XAUTHORITY=/x -- picom --config /c\n"
+	if string(got) != want {
+		t.Fatalf("detach ran:\n%s\nwant:\n%s", got, want)
+	}
+	if err := (Session{}).detach("x", "y"); !errors.Is(err, ErrNoBus) {
+		t.Fatalf("no runtime directory: %v", err)
+	}
+}
+
+// fakeBinaries puts shell scripts named for programs first on PATH, and answers their directory.
+func fakeBinaries(t *testing.T, scripts map[string]string) string {
+	t.Helper()
+	dir := t.TempDir()
+	for name, body := range scripts {
+		if err := os.WriteFile(filepath.Join(dir, name), []byte("#!/bin/sh\n"+body+"\n"), 0o755); err != nil {
+			t.Fatal(err)
+		}
+	}
+	t.Setenv("PATH", dir+string(os.PathListSeparator)+os.Getenv("PATH"))
+	return dir
+}

modules/dunst/files/dunstrc

@@ -0,0 +1,92 @@
+# dunst, the notifier (module dunst, novox/hq ADR 0208). Owned by the mesh: this file is replaced
+# at every push. Adopted from the laptop's file of 2026-10-04 (the two workstations differed in
+# position, transparency and corner radius; the laptop's square, opaque, top-right one matches the
+# rest of the desktop). Only what differs from dunst's defaults, and what the desktop relies on.
+#
+# Other modules' rules go in ~/.config/dunst/dunstrc.d/*.conf, which dunst reads after this file,
+# so a drop-in outranks it. dunst is started by D-Bus on the first notification: nothing starts it.
+
+[global]
+    monitor = 0
+    follow = none
+
+    # Geometry
+    width = 250
+    height = (0, 300)
+    origin = top-right
+    offset = (10, 50)
+    notification_limit = 20
+
+    progress_bar = true
+    progress_bar_height = 10
+    progress_bar_frame_width = 1
+    progress_bar_min_width = 150
+    progress_bar_max_width = 300
+
+    indicate_hidden = yes
+    transparency = 0
+    separator_height = 2
+    padding = 8
+    horizontal_padding = 8
+    text_icon_padding = 0
+    frame_width = 3
+    frame_color = "#de5200"
+    gap_size = 0
+    separator_color = frame
+    sort = yes
+    corner_radius = 0
+
+    # Text: the interface face (research 026/04)
+    font = Inter 10
+    line_height = 0
+    markup = full
+    format = "<b>%s</b>\n%b"
+    alignment = left
+    vertical_alignment = center
+    show_age_threshold = 60
+    ellipsize = middle
+    ignore_newline = no
+    stack_duplicates = true
+    hide_duplicate_count = false
+    show_indicators = yes
+
+    # Icons, from the desktop's icon theme
+    enable_recursive_icon_lookup = true
+    icon_theme = Adwaita
+    icon_position = left
+    min_icon_size = 32
+    max_icon_size = 128
+
+    # History
+    sticky_history = yes
+    history_length = 20
+
+    # The context menu is the node's dmenu-compatible command, which the holder of node-launcher
+    # answers (rofi on the workstations). Links open in the desktop's default browser.
+    dmenu = dmenu -p dunst
+    browser = /usr/bin/xdg-open
+    always_run_script = true
+
+    title = Dunst
+    class = Dunst
+    ignore_dbusclose = false
+
+    mouse_left_click = close_current
+    mouse_middle_click = do_action, close_current
+    mouse_right_click = close_all
+
+[urgency_low]
+    background = "#000000"
+    foreground = "#ffffff"
+    timeout = 10
+
+[urgency_normal]
+    background = "#000000"
+    foreground = "#ffffff"
+    timeout = 10
+
+[urgency_critical]
+    background = "#000000"
+    foreground = "#ffffff"
+    frame_color = "#ff0000"
+    timeout = 0

modules/dunst/go.mod

@@ -0,0 +1,5 @@
+module dunst
+
+go 1.22
+
+require git.novox.be/novox/mesh-sdk/go v0.1.7

modules/dunst/go.sum

@@ -0,0 +1,2 @@
+git.novox.be/novox/mesh-sdk/go v0.1.7 h1:C0sTQmtTiyYH7bnqZb7PusXnqA37gKuT7Nqjn9gG47w=
+git.novox.be/novox/mesh-sdk/go v0.1.7/go.mod h1:GFuZUElBZ9A++mxgIKo97aXXo+kV0uJ/UkbhQPPIbrY=

modules/dunst/module.json

@@ -0,0 +1,73 @@
+{
+  "module": "dunst",
+  "version": "1",
+  "capabilities": [
+    "package-manager"
+  ],
+  "claims": [
+    {
+      "name": "node-notifier",
+      "scope": "node",
+      "serves": [
+        "send",
+        "history"
+      ]
+    }
+  ],
+  "tools": [
+    "dunst_pause",
+    "dunst_resume",
+    "dunst_close_all",
+    "dunst_rules",
+    "dunst_count"
+  ],
+  "resources": [
+    {
+      "id": "package",
+      "type": "package",
+      "package": "dunst"
+    },
+    {
+      "id": "client",
+      "type": "package",
+      "package": "libnotify"
+    },
+    {
+      "id": "configuration-dir",
+      "type": "directory",
+      "path": "${machine:account-home}/.config/dunst",
+      "owner": "${machine:account}",
+      "mode": "0755"
+    },
+    {
+      "id": "dropins",
+      "type": "directory",
+      "path": "${machine:account-home}/.config/dunst/dunstrc.d",
+      "owner": "${machine:account}",
+      "mode": "0755"
+    },
+    {
+      "id": "configuration",
+      "type": "file",
+      "path": "${machine:account-home}/.config/dunst/dunstrc",
+      "owner": "${machine:account}",
+      "mode": "0644",
+      "content": "# dunst, the notifier (module dunst, novox/hq ADR 0208). Owned by the mesh: this file is replaced\n# at every push. Adopted from the laptop's file of 2026-10-04 (the two workstations differed in\n# position, transparency and corner radius; the laptop's square, opaque, top-right one matches the\n# rest of the desktop). Only what differs from dunst's defaults, and what the desktop relies on.\n#\n# Other modules' rules go in ~/.config/dunst/dunstrc.d/*.conf, which dunst reads after this file,\n# so a drop-in outranks it. dunst is started by D-Bus on the first notification: nothing starts it.\n\n[global]\n    monitor = 0\n    follow = none\n\n    # Geometry\n    width = 250\n    height = (0, 300)\n    origin = top-right\n    offset = (10, 50)\n    notification_limit = 20\n\n    progress_bar = true\n    progress_bar_height = 10\n    progress_bar_frame_width = 1\n    progress_bar_min_width = 150\n    progress_bar_max_width = 300\n\n    indicate_hidden = yes\n    transparency = 0\n    separator_height = 2\n    padding = 8\n    horizontal_padding = 8\n    text_icon_padding = 0\n    frame_width = 3\n    frame_color = \"#de5200\"\n    gap_size = 0\n    separator_color = frame\n    sort = yes\n    corner_radius = 0\n\n    # Text: the interface face (research 026/04)\n    font = Inter 10\n    line_height = 0\n    markup = full\n    format = \"<b>%s</b>\\n%b\"\n    alignment = left\n    vertical_alignment = center\n    show_age_threshold = 60\n    ellipsize = middle\n    ignore_newline = no\n    stack_duplicates = true\n    hide_duplicate_count = false\n    show_indicators = yes\n\n    # Icons, from the desktop's icon theme\n    enable_recursive_icon_lookup = true\n    icon_theme = Adwaita\n    icon_position = left\n    min_icon_size = 32\n    max_icon_size = 128\n\n    # History\n    sticky_history = yes\n    history_length = 20\n\n    # The context menu is the node's dmenu-compatible command, which the holder of node-launcher\n    # answers (rofi on the workstations). Links open in the desktop's default browser.\n    dmenu = dmenu -p dunst\n    browser = /usr/bin/xdg-open\n    always_run_script = true\n\n    title = Dunst\n    class = Dunst\n    ignore_dbusclose = false\n\n    mouse_left_click = close_current\n    mouse_middle_click = do_action, close_current\n    mouse_right_click = close_all\n\n[urgency_low]\n    background = \"#000000\"\n    foreground = \"#ffffff\"\n    timeout = 10\n\n[urgency_normal]\n    background = \"#000000\"\n    foreground = \"#ffffff\"\n    timeout = 10\n\n[urgency_critical]\n    background = \"#000000\"\n    foreground = \"#ffffff\"\n    frame_color = \"#ff0000\"\n    timeout = 0\n"
+    }
+  ],
+  "build": {
+    "artifacts": [
+      {
+        "name": "tools",
+        "kind": "bundle",
+        "language": "go",
+        "system": "arch",
+        "from": "cmd/dunst-tools",
+        "binary": "dunst-tools",
+        "loads": [
+          "dunst-tools"
+        ]
+      }
+    ]
+  }
+}

modules/feh/README.md

@@ -0,0 +1,47 @@
+# feh
+
+The wallpaper as a module (novox/hq ADR 0208, research 026/05).
+
+- Installs `feh` and requires `x11-display` on its own machine. It holds no seat: a wallpaper is not a
+  role anything else calls.
+- **Carries the wallpaper itself.** `wallpaper/default.jpg` is built into an archive of the module
+  (ADR 0205) and unpacked into `~/.local/share/feh/wallpapers/`, which the module owns.
+- Owns `~/.fehbg`, which sets that image, filled, on every monitor, without rewriting itself
+  (`--no-fehbg`).
+- Runs `~/.fehbg` once per session, from the session's start (the `xinitrc` slot `normal`).
+- Binds `$mod+Shift+b` to the same file, as its own i3 drop-in (`50-feh.conf`): the declared wallpaper
+  back, after a monitor change.
+
+## Tools
+
+| tool | does |
+|---|---|
+| `feh_set` | set images (one for all monitors, or one each) in a mode: fill, center, max, scale, tile. For this session; the declared wallpaper returns at the next login |
+| `feh_current` | the declared wallpaper (from `~/.fehbg`) and the one `feh_set` put up in this session |
+
+`feh_set` never writes `~/.fehbg`. A wallpaper that should stay is a change to this module, or a
+setting once issue 168 closes, not a file the next push would overwrite.
+
+## What it improves on what was found
+
+- **The wallpaper no longer lives in the predecessor's tree.** `~/.fehbg` pointed into a directory
+  of the retired predecessor's. Deleting that directory would have left the desktop black, silently.
+- **One image file, the same on both workstations.** The image was byte-identical on both. It is now
+  the module's own.
+
+## What it leaves as found
+
+- The predecessor's wallpaper directory. It is part of the predecessor's tree, which goes as a whole.
+
+## Migration (ADR 0182)
+
+- The first push keeps the found `~/.fehbg` once, then writes the module's.
+- Once the `xorg` module writes the session's start, delete the `~/.fehbg &` line from your own part
+  of `~/.xinitrc`.
+- The image's origin is the predecessor's desktop module. Check that it may be redistributed before
+  this catalogue is published anywhere public.
+
+## Blockers
+
+- `x11-display` and the `xinitrc` slot are ADR 0208's. Until the controller knows them, `mctl` reads
+  them as unknown.

modules/feh/cmd/feh-tools/args.go

@@ -0,0 +1,97 @@
+// Reading a tool's arguments: JSON numbers arrive as float64, and a missing argument is its default.
+// The same in every desktop module that carries it.
+package main
+
+import (
+	"fmt"
+	"math"
+	"strings"
+	"time"
+)
+
+// text is a string argument, trimmed; required says an empty one is refused.
+func text(args map[string]any, key string, required bool) (string, error) {
+	v, present := args[key]
+	if !present || v == nil {
+		if required {
+			return "", fmt.Errorf("%s is required", key)
+		}
+		return "", nil
+	}
+	s, ok := v.(string)
+	if !ok {
+		return "", fmt.Errorf("%s is a string, not %T", key, v)
+	}
+	s = strings.TrimSpace(s)
+	if s == "" && required {
+		return "", fmt.Errorf("%s is required", key)
+	}
+	return s, nil
+}
+
+// whole is a whole-number argument within [least, most], or def when absent.
+func whole(args map[string]any, key string, def, least, most int) (int, error) {
+	v, present := args[key]
+	if !present || v == nil {
+		return def, nil
+	}
+	f, ok := v.(float64)
+	if !ok {
+		if i, isInt := v.(int); isInt {
+			f = float64(i)
+		} else {
+			return 0, fmt.Errorf("%s is a number, not %T", key, v)
+		}
+	}
+	if f != math.Trunc(f) {
+		return 0, fmt.Errorf("%s is a whole number, not %v", key, f)
+	}
+	n := int(f)
+	if n < least || n > most {
+		return 0, fmt.Errorf("%s is %d; it is between %d and %d", key, n, least, most)
+	}
+	return n, nil
+}
+
+// flag is a boolean argument, or def when absent.
+func flag(args map[string]any, key string, def bool) (bool, error) {
+	v, present := args[key]
+	if !present || v == nil {
+		return def, nil
+	}
+	b, ok := v.(bool)
+	if !ok {
+		return false, fmt.Errorf("%s is true or false, not %T", key, v)
+	}
+	return b, nil
+}
+
+// texts is a list-of-strings argument.
+func texts(args map[string]any, key string) ([]string, error) {
+	v, present := args[key]
+	if !present || v == nil {
+		return nil, nil
+	}
+	list, ok := v.([]any)
+	if !ok {
+		if ss, isStrings := v.([]string); isStrings {
+			return ss, nil
+		}
+		return nil, fmt.Errorf("%s is a list of strings, not %T", key, v)
+	}
+	out := make([]string, 0, len(list))
+	for i, item := range list {
+		s, ok := item.(string)
+		if !ok {
+			return nil, fmt.Errorf("%s[%d] is a string, not %T", key, i, item)
+		}
+		out = append(out, s)
+	}
+	return out, nil
+}
+
+// seconds is a timeout argument in seconds, defaulted and bounded below the runtime's call limit.
+func seconds(args map[string]any, key string, def, most int) (time.Duration, error) {
+	n, err := whole(args, key, def, 1, most)
+	return time.Duration(n) * time.Second, err
+}

modules/feh/cmd/feh-tools/main.go

@@ -0,0 +1,53 @@
+// feh's Go tools bundle (novox/hq ADR 0188, ADR 0193, ADR 0208): the wallpaper's tools, served by the
+// node's runtime as the operator account.
+package main
+
+import (
+	"fmt"
+	"os"
+
+	stdio "git.novox.be/novox/mesh-sdk/go"
+)
+
+func main() {
+	if err := stdio.Serve("", tools()); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
+
+func tools() []stdio.Tool {
+	return []stdio.Tool{
+		{
+			Name: "feh_set",
+			Description: "Set the wallpaper in the operator's session: one image for every monitor, or one per " +
+				"monitor in the X screen order, filled, centred, scaled to fit, stretched or tiled. Lasts until the " +
+				"next session start, when the declared wallpaper returns; the declared one is untouched.",
+			Input: map[string]any{
+				"type": "object",
+				"properties": map[string]any{
+					"images": map[string]any{"type": "array", "items": map[string]any{"type": "string"}, "description": "image files on this machine, absolute or under the account's home; one per monitor, or one for all"},
+					"mode":   map[string]any{"type": "string", "enum": modes, "description": "default fill"},
+				},
+				"required": []string{"images"},
+			},
+			Run: func(args map[string]any) (any, error) {
+				images, err := texts(args, "images")
+				if err != nil {
+					return nil, err
+				}
+				mode, err := text(args, "mode", false)
+				if err != nil {
+					return nil, err
+				}
+				return Set(images, mode)
+			},
+		},
+		{
+			Name: "feh_current",
+			Description: "The wallpaper: the declared one the session start sets (images and mode, read from " +
+				"~/.fehbg), and the one feh_set put up in this session, if any.",
+			Run: func(map[string]any) (any, error) { return Current() },
+		},
+	}
+}

modules/feh/cmd/feh-tools/manifest_helpers_test.go

@@ -0,0 +1,175 @@
+package main
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+// The module's manifest, read the way the catalogue reads it, for the manifest tests. The same in
+// every desktop module that carries it.
+
+type manifest struct {
+	Module       string           `json:"module"`
+	Version      string           `json:"version"`
+	Capabilities []string         `json:"capabilities"`
+	Requires     []string         `json:"requires"`
+	Claims       []claim          `json:"claims"`
+	Seats        []any            `json:"seats"`
+	Tools        []string         `json:"tools"`
+	Environment  *environment     `json:"environment"`
+	Shell        []shellCode      `json:"shell"`
+	Resources    []map[string]any `json:"resources"`
+	Build        struct {
+		Artifacts []map[string]any `json:"artifacts"`
+	} `json:"build"`
+}
+
+type claim struct {
+	Name   string   `json:"name"`
+	Scope  string   `json:"scope"`
+	Serves []string `json:"serves"`
+}
+
+type environment struct {
+	Variables map[string]string `json:"variables"`
+	Path      []map[string]any  `json:"path"`
+}
+
+type shellCode struct {
+	For  string `json:"for"`
+	Slot string `json:"slot"`
+	Code string `json:"code"`
+}
+
+func readManifest(t *testing.T) manifest {
+	t.Helper()
+	raw, err := os.ReadFile(filepath.Join("..", "..", "module.json"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	dec := json.NewDecoder(strings.NewReader(string(raw)))
+	dec.DisallowUnknownFields()
+	var m manifest
+	if err := dec.Decode(&m); err != nil {
+		t.Fatalf("module.json: %v", err)
+	}
+	return m
+}
+
+func (m manifest) resource(t *testing.T, id string) map[string]any {
+	t.Helper()
+	for _, r := range m.Resources {
+		if r["id"] == id {
+			return r
+		}
+	}
+	t.Fatalf("no resource %q", id)
+	return nil
+}
+
+func (m manifest) packages() (present, absent []string) {
+	for _, r := range m.Resources {
+		if r["type"] == "package" {
+			if r["absent"] == true {
+				absent = append(absent, r["package"].(string))
+			} else {
+				present = append(present, r["package"].(string))
+			}
+		}
+	}
+	return present, absent
+}
+
+// sameAsSource checks that a file resource's content is byte for byte the module's source file, so
+// the readable file in the repository is what the machine gets.
+func (m manifest) sameAsSource(t *testing.T, id, source string) {
+	t.Helper()
+	want, err := os.ReadFile(filepath.Join("..", "..", source))
+	if err != nil {
+		t.Fatal(err)
+	}
+	r := m.resource(t, id)
+	if r["type"] != "file" {
+		t.Fatalf("%s is a %v, not a file", id, r["type"])
+	}
+	if got, _ := r["content"].(string); got != string(want) {
+		t.Fatalf("resource %s's content is not %s: edit the source and copy it into module.json", id, source)
+	}
+	if r["owner"] != "${machine:account}" && !strings.HasPrefix(r["path"].(string), "/etc/") {
+		t.Fatalf("%s under the home is the account's", id)
+	}
+}
+
+// checkTheToolsAgree checks that the manifest lists the module's own tools exactly, that the bundle
+// serves each seat verb the claims promise as <seat>.<verb>, and that the Go bundle is declared.
+func checkTheToolsAgree(t *testing.T, m manifest) {
+	t.Helper()
+	own, seat := map[string]bool{}, map[string]bool{}
+	for _, tool := range tools() {
+		if strings.Contains(tool.Name, ".") {
+			seat[tool.Name] = true
+		} else {
+			own[tool.Name] = true
+		}
+		if strings.TrimSpace(tool.Description) == "" {
+			t.Errorf("%s has no description", tool.Name)
+		}
+	}
+	listed := map[string]bool{}
+	for _, name := range m.Tools {
+		listed[name] = true
+		if !own[name] {
+			t.Errorf("module.json lists %s, which the bundle does not serve", name)
+		}
+	}
+	for name := range own {
+		if !listed[name] {
+			t.Errorf("the bundle serves %s, which module.json does not list", name)
+		}
+		if !strings.HasPrefix(name, strings.ReplaceAll(m.Module, "-", "_")+"_") {
+			t.Errorf("%s is not prefixed with the module's name", name)
+		}
+	}
+	promised := map[string]bool{}
+	for _, c := range m.Claims {
+		for _, verb := range c.Serves {
+			promised[c.Name+"."+verb] = true
+			if !seat[c.Name+"."+verb] {
+				t.Errorf("the claim on %s promises %s, which the bundle does not serve", c.Name, verb)
+			}
+		}
+	}
+	for name := range seat {
+		if !promised[name] {
+			t.Errorf("the bundle serves %s, which no claim promises", name)
+		}
+	}
+	var bundle map[string]any
+	for _, a := range m.Build.Artifacts {
+		if a["kind"] == "bundle" {
+			bundle = a
+		}
+	}
+	if bundle == nil || bundle["language"] != "go" || bundle["system"] != "arch" ||
+		bundle["from"] != "cmd/"+m.Module+"-tools" || bundle["binary"] != m.Module+"-tools" {
+		t.Errorf("the Go tools bundle: %v", bundle)
+	}
+}
+
+// checkNoSecretsOrInstallationNames refuses what a catalogue manifest must never carry.
+func checkNoSecretsOrInstallationNames(t *testing.T) {
+	t.Helper()
+	raw, err := os.ReadFile(filepath.Join("..", "..", "module.json"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	s := strings.ToLower(string(raw))
+	for _, never := range []string{"/home/", "jochen", "g14", "shanks", "novox.be", "api_key", ".hal/", "greenclip daemon"} {
+		if strings.Contains(s, never) {
+			t.Errorf("module.json names %q", never)
+		}
+	}
+}

modules/feh/cmd/feh-tools/manifest_test.go

@@ -0,0 +1,79 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"reflect"
+	"strings"
+	"testing"
+)
+
+// feh's shape (novox/hq ADR 0208): no seat; it requires the X display on its own machine, carries
+// the wallpaper as its own archive (ADR 0205), owns ~/.fehbg pointing at it, and sets it once from
+// the session's start.
+
+func TestItRequiresTheXDisplayAndClaimsNothing(t *testing.T) {
+	m := readManifest(t)
+	if m.Module != "feh" || m.Seats != nil || m.Claims != nil {
+		t.Fatalf("module %q, seats %v, claims %v", m.Module, m.Seats, m.Claims)
+	}
+	if !reflect.DeepEqual(m.Requires, []string{"x11-display"}) {
+		t.Fatalf("requires: %v", m.Requires)
+	}
+	if present, absent := m.packages(); !reflect.DeepEqual(present, []string{"feh"}) || absent != nil {
+		t.Fatalf("packages: %v, absent %v", present, absent)
+	}
+}
+
+func TestTheWallpaperIsTheModulesOwnArchive(t *testing.T) {
+	m := readManifest(t)
+	a := m.resource(t, "wallpapers")
+	if a["type"] != "archive" || a["artifact"] != "wallpapers" || a["path"] != "${machine:account-home}/.local/share/feh/wallpapers" || a["owner"] != "${machine:account}" {
+		t.Fatalf("%v", a)
+	}
+	found := false
+	for _, art := range m.Build.Artifacts {
+		if art["name"] == "wallpapers" && art["kind"] == "archive" && art["from"] == "wallpaper" {
+			found = true
+		}
+	}
+	if !found {
+		t.Fatal("no archive artifact built from wallpaper/")
+	}
+	info, err := os.Stat(filepath.Join("..", "..", "wallpaper", "default.jpg"))
+	if err != nil || info.Size() == 0 {
+		t.Fatalf("the image: %v", err)
+	}
+}
+
+func TestFehbgIsOwnedAndTheSessionStartRunsItOnce(t *testing.T) {
+	m := readManifest(t)
+	m.sameAsSource(t, "fehbg", "files/fehbg")
+	f := m.resource(t, "fehbg")
+	if f["path"] != "${machine:account-home}/.fehbg" || f["mode"] != "0755" {
+		t.Fatalf("%v", f)
+	}
+	if c := f["content"].(string); !strings.Contains(c, "$HOME/.local/share/feh/wallpapers/default.jpg") || strings.Contains(c, ".hal") {
+		t.Fatalf("%s", c)
+	}
+	if len(m.Shell) != 1 || m.Shell[0].For != "xinitrc" || m.Shell[0].Slot != "normal" || strings.Count(m.Shell[0].Code, `"$HOME/.fehbg"`) != 1 {
+		t.Fatalf("%+v", m.Shell)
+	}
+}
+
+func TestTheKeyThatRestoresTheWallpaperIsAnI3DropIn(t *testing.T) {
+	m := readManifest(t)
+	m.sameAsSource(t, "i3-bindings", "files/i3/50-feh.conf")
+	if p := m.resource(t, "i3-bindings")["path"]; p != "${machine:account-home}/.config/i3/config.d/50-feh.conf" {
+		t.Fatalf("path: %v", p)
+	}
+	if c := m.resource(t, "i3-bindings")["content"].(string); !strings.Contains(c, "bindsym $mod+Shift+b exec --no-startup-id ~/.fehbg\n") {
+		t.Fatalf("%s", c)
+	}
+}
+
+func TestTheToolsAgreeWithTheManifest(t *testing.T) {
+	m := readManifest(t)
+	checkTheToolsAgree(t, m)
+	checkNoSecretsOrInstallationNames(t)
+}

modules/feh/cmd/feh-tools/session.go

@@ -0,0 +1,423 @@
+// The operator's graphical session, as a tool the node's runtime runs finds it (novox/hq ADR 0208).
+//
+// The runtime is a system service running as the operator account (ADR 0175): it has the account's
+// uid and none of the session's environment — no DISPLAY, no XAUTHORITY, no session bus. A tool that
+// draws on the screen or talks to the desktop's D-Bus must find them. It reads them from a process of
+// the account that is part of the session (the window manager first), the same thing `loginctl` and
+// a person's own shell would point at, and says where it found them.
+//
+// Long-lived programs a tool starts go to the account's own service manager through `systemd-run
+// --user`, never as children of the tool: the runtime's unit is a cgroup the service manager empties
+// whenever the runtime restarts, and a compositor or a clipboard owner started from inside it would
+// die with it.
+//
+// This file is the same in every desktop module that carries it; it moves into the Go SDK once a
+// second consumer outside the desktop wants it.
+package main
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"sort"
+	"strconv"
+	"strings"
+	"syscall"
+	"time"
+)
+
+// Where the session is looked for. Variables so a test can point them at a fake tree.
+var (
+	procRoot   = "/proc"
+	runUserDir = "/run/user"
+	x11Sockets = "/tmp/.X11-unix"
+)
+
+// sessionHolders are the processes whose environment is the session's, best first: the window
+// manager is the session, the rest are its children. Anything else carrying DISPLAY ranks after them.
+var sessionHolders = []string{"i3", "sway", "i3bar", "picom", "xss-lock", "dunst", "clipmenud", "xterm"}
+
+// sessionKeys are the variables a session carries that a tool hands on to what it runs.
+var sessionKeys = []string{"DISPLAY", "XAUTHORITY", "WAYLAND_DISPLAY", "DBUS_SESSION_BUS_ADDRESS",
+	"XDG_RUNTIME_DIR", "XDG_SESSION_ID", "I3SOCK"}
+
+// Session is what a tool needs to reach the operator's desktop.
+type Session struct {
+	UID        int    `json:"uid"`
+	Display    string `json:"display,omitempty"`
+	XAuthority string `json:"xauthority,omitempty"`
+	Wayland    string `json:"wayland_display,omitempty"`
+	Bus        string `json:"bus,omitempty"`
+	RuntimeDir string `json:"runtime_dir,omitempty"`
+	SessionID  string `json:"session_id,omitempty"`
+	I3Sock     string `json:"i3sock,omitempty"`
+	// From says where the values were found: the tool's own environment, a process, or the socket.
+	From string `json:"from"`
+}
+
+// ErrNoSession is answered by a tool that needs the desktop when nobody is logged in to it.
+var ErrNoSession = errors.New("no graphical session")
+
+// ErrTimedOut is what run answers for a command ended because it ran past its time.
+var ErrTimedOut = errors.New("timed out")
+
+// ErrNoBus is answered by a tool that needs the session bus when the account has none.
+var ErrNoBus = errors.New("no session bus")
+
+// operatorHome is the account's home: what the runtime was told, else the process's own.
+func operatorHome() string {
+	if h := strings.TrimSpace(os.Getenv("MESH_OPERATOR_HOME")); h != "" {
+		return h
+	}
+	h, _ := os.UserHomeDir()
+	return h
+}
+
+// findSession finds the graphical session of the account this tool runs as, or answers
+// ErrNoSession with what it looked at.
+func findSession() (Session, error) {
+	s := findEnvironment()
+	if s.Display == "" && s.Wayland == "" {
+		return s, fmt.Errorf("%w for uid %d on this machine: no process of the account carries DISPLAY "+
+			"or WAYLAND_DISPLAY, and no X server socket in %s has an authority file to go with it. "+
+			"Is anyone logged in to the desktop?", ErrNoSession, s.UID, x11Sockets)
+	}
+	return s, nil
+}
+
+// findBus finds the account's session bus, which a logged-in account has whether or not a desktop
+// is running.
+func findBus() (Session, error) {
+	s := findEnvironment()
+	if s.Bus == "" {
+		return s, fmt.Errorf("%w for uid %d: DBUS_SESSION_BUS_ADDRESS is not set and %s does not exist "+
+			"(the account is not logged in)", ErrNoBus, s.UID, filepath.Join(runUserDir, strconv.Itoa(s.UID), "bus"))
+	}
+	return s, nil
+}
+
+func findEnvironment() Session {
+	uid := os.Getuid()
+	s := Session{UID: uid}
+	own := map[string]string{}
+	for _, k := range sessionKeys {
+		own[k] = os.Getenv(k)
+	}
+	if own["DISPLAY"] != "" || own["WAYLAND_DISPLAY"] != "" {
+		s.fill(own)
+		s.From = "the tool's own environment"
+	} else if pid, comm, env, ok := sessionProcess(uid); ok {
+		s.fill(env)
+		s.From = fmt.Sprintf("process %s (pid %d)", comm, pid)
+	} else if display, ok := lonelyX11Socket(); ok {
+		if a := filepath.Join(operatorHome(), ".Xauthority"); exists(a) {
+			s.Display, s.XAuthority = display, a
+			s.From = "the X server socket and the account's ~/.Xauthority"
+		}
+		s.fill(own)
+	} else {
+		s.fill(own)
+		s.From = "nothing: no session found"
+	}
+	// The bus and the runtime directory are the account's, whether or not the process named them.
+	runtime := filepath.Join(runUserDir, strconv.Itoa(uid))
+	if s.RuntimeDir == "" && exists(runtime) {
+		s.RuntimeDir = runtime
+	}
+	if s.Bus == "" && s.RuntimeDir != "" && exists(filepath.Join(s.RuntimeDir, "bus")) {
+		s.Bus = "unix:path=" + filepath.Join(s.RuntimeDir, "bus")
+	}
+	return s
+}
+
+func (s *Session) fill(env map[string]string) {
+	set := func(dst *string, key string) {
+		if *dst == "" {
+			*dst = env[key]
+		}
+	}
+	set(&s.Display, "DISPLAY")
+	set(&s.XAuthority, "XAUTHORITY")
+	set(&s.Wayland, "WAYLAND_DISPLAY")
+	set(&s.Bus, "DBUS_SESSION_BUS_ADDRESS")
+	set(&s.RuntimeDir, "XDG_RUNTIME_DIR")
+	set(&s.SessionID, "XDG_SESSION_ID")
+	set(&s.I3Sock, "I3SOCK")
+}
+
+// sessionProcess is the best process of this uid whose environment names a display.
+func sessionProcess(uid int) (int, string, map[string]string, bool) {
+	entries, err := os.ReadDir(procRoot)
+	if err != nil {
+		return 0, "", nil, false
+	}
+	type candidate struct {
+		pid  int
+		comm string
+		env  map[string]string
+		rank int
+	}
+	var found []candidate
+	for _, e := range entries {
+		pid, err := strconv.Atoi(e.Name())
+		if err != nil {
+			continue
+		}
+		dir := filepath.Join(procRoot, e.Name())
+		if owner, ok := ownerOf(dir); !ok || owner != uid {
+			continue
+		}
+		raw, err := os.ReadFile(filepath.Join(dir, "environ"))
+		if err != nil {
+			continue
+		}
+		env := parseEnviron(raw)
+		if env["DISPLAY"] == "" && env["WAYLAND_DISPLAY"] == "" {
+			continue
+		}
+		comm := readTrimmed(filepath.Join(dir, "comm"))
+		rank := len(sessionHolders)
+		for i, h := range sessionHolders {
+			if h == comm {
+				rank = i
+				break
+			}
+		}
+		found = append(found, candidate{pid, comm, env, rank})
+	}
+	if len(found) == 0 {
+		return 0, "", nil, false
+	}
+	sort.Slice(found, func(i, j int) bool {
+		if found[i].rank != found[j].rank {
+			return found[i].rank < found[j].rank
+		}
+		return found[i].pid > found[j].pid // the newer of two equals
+	})
+	best := found[0]
+	return best.pid, best.comm, best.env, true
+}
+
+func parseEnviron(raw []byte) map[string]string {
+	env := map[string]string{}
+	for _, kv := range bytes.Split(raw, []byte{0}) {
+		if i := bytes.IndexByte(kv, '='); i > 0 {
+			env[string(kv[:i])] = string(kv[i+1:])
+		}
+	}
+	return env
+}
+
+func ownerOf(path string) (int, bool) {
+	info, err := os.Stat(path)
+	if err != nil {
+		return 0, false
+	}
+	st, ok := info.Sys().(*syscall.Stat_t)
+	if !ok {
+		return 0, false
+	}
+	return int(st.Uid), true
+}
+
+// lonelyX11Socket is the display of the one X server socket there is, when there is exactly one.
+func lonelyX11Socket() (string, bool) {
+	entries, err := os.ReadDir(x11Sockets)
+	if err != nil {
+		return "", false
+	}
+	var displays []string
+	for _, e := range entries {
+		if n := strings.TrimPrefix(e.Name(), "X"); n != e.Name() {
+			if _, err := strconv.Atoi(n); err == nil {
+				displays = append(displays, ":"+n)
+			}
+		}
+	}
+	if len(displays) != 1 {
+		return "", false
+	}
+	return displays[0], true
+}
+
+func readTrimmed(path string) string {
+	b, err := os.ReadFile(path)
+	if err != nil {
+		return ""
+	}
+	return strings.TrimSpace(string(b))
+}
+
+func exists(path string) bool {
+	_, err := os.Stat(path)
+	return err == nil
+}
+
+// Env is this process's environment with the session's variables in place of its own.
+func (s Session) Env() []string {
+	drop := map[string]bool{}
+	for _, k := range sessionKeys {
+		drop[k] = true
+	}
+	var env []string
+	for _, kv := range os.Environ() {
+		if i := strings.IndexByte(kv, '='); i > 0 && drop[kv[:i]] {
+			continue
+		}
+		env = append(env, kv)
+	}
+	add := func(k, v string) {
+		if v != "" {
+			env = append(env, k+"="+v)
+		}
+	}
+	add("DISPLAY", s.Display)
+	add("XAUTHORITY", s.XAuthority)
+	add("WAYLAND_DISPLAY", s.Wayland)
+	add("DBUS_SESSION_BUS_ADDRESS", s.Bus)
+	add("XDG_RUNTIME_DIR", s.RuntimeDir)
+	add("XDG_SESSION_ID", s.SessionID)
+	add("I3SOCK", s.I3Sock)
+	return env
+}
+
+// mostOutput bounds what a command may answer with, per stream.
+const mostOutput = 256 << 10
+
+// Result is what a command did.
+type Result struct {
+	Stdout    string `json:"stdout"`
+	Stderr    string `json:"stderr,omitempty"`
+	Code      int    `json:"code"`
+	Truncated bool   `json:"truncated,omitempty"`
+}
+
+// run runs a command in the session's environment, its input given, ended with everything it
+// started after timeout. A command that is not installed is an error naming it; one that exits
+// non-zero is a Result with its code, for the caller to judge.
+func (s Session) run(timeout time.Duration, stdin string, name string, args ...string) (Result, error) {
+	path, err := exec.LookPath(name)
+	if err != nil {
+		return Result{}, fmt.Errorf("%s is not installed on this machine", name)
+	}
+	cmd := exec.Command(path, args...)
+	cmd.Env = s.Env()
+	if home := operatorHome(); exists(home) {
+		cmd.Dir = home
+	}
+	if stdin != "" {
+		cmd.Stdin = strings.NewReader(stdin)
+	}
+	var out, errOut capped
+	cmd.Stdout, cmd.Stderr = &out, &errOut
+	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+	if err := cmd.Start(); err != nil {
+		return Result{}, fmt.Errorf("%s: %w", name, err)
+	}
+	done := make(chan error, 1)
+	go func() { done <- cmd.Wait() }()
+	select {
+	case err = <-done:
+	case <-time.After(timeout):
+		_ = syscall.Kill(-cmd.Process.Pid, syscall.SIGKILL)
+		<-done
+		return Result{Stdout: out.String(), Stderr: errOut.String()},
+			fmt.Errorf("%s did not finish within %s and was ended: %w", name, timeout, ErrTimedOut)
+	}
+	r := Result{Stdout: out.String(), Stderr: errOut.String(), Truncated: out.cut || errOut.cut}
+	var exit *exec.ExitError
+	if errors.As(err, &exit) {
+		r.Code = exit.ExitCode()
+	} else if err != nil {
+		return r, fmt.Errorf("%s: %w", name, err)
+	}
+	return r, nil
+}
+
+// detach starts a long-lived program under the account's own service manager, as a transient unit
+// that carries the session's display, so it outlives the runtime that asked for it. A unit already
+// running under the same name is stopped first, so a fixed name means "at most one".
+func (s Session) detach(unit string, args ...string) error {
+	if s.RuntimeDir == "" {
+		return fmt.Errorf("%w: the account's runtime directory is missing, so its service manager "+
+			"cannot be reached", ErrNoBus)
+	}
+	_, _ = s.run(5*time.Second, "", "systemctl", "--user", "stop", unit+".service")
+	call := []string{"--user", "--collect", "--quiet", "--unit=" + unit}
+	for _, kv := range [][2]string{{"DISPLAY", s.Display}, {"XAUTHORITY", s.XAuthority},
+		{"WAYLAND_DISPLAY", s.Wayland}, {"XDG_SESSION_ID", s.SessionID}, {"I3SOCK", s.I3Sock}} {
+		if kv[1] != "" {
+			call = append(call, "--setenv="+kv[0]+"="+kv[1])
+		}
+	}
+	call = append(call, "--")
+	call = append(call, args...)
+	r, err := s.run(10*time.Second, "", "systemd-run", call...)
+	if err != nil {
+		return err
+	}
+	if r.Code != 0 {
+		return fmt.Errorf("systemd-run %s: %s", unit, strings.TrimSpace(r.Stderr))
+	}
+	return nil
+}
+
+// uniqueUnit is a transient unit name that will not collide with an earlier one.
+func uniqueUnit(prefix string) string {
+	return fmt.Sprintf("%s-%d", prefix, time.Now().UnixNano())
+}
+
+type capped struct {
+	bytes.Buffer
+	cut bool
+}
+
+func (c *capped) Write(p []byte) (int, error) {
+	if room := mostOutput - c.Len(); room < len(p) {
+		if room > 0 {
+			c.Buffer.Write(p[:room])
+		}
+		c.cut = true
+		return len(p), nil
+	}
+	return c.Buffer.Write(p)
+}
+
+// processesOf are the pids of this uid's processes whose command name is comm, oldest first.
+func processesOf(comm string) []int {
+	entries, err := os.ReadDir(procRoot)
+	if err != nil {
+		return nil
+	}
+	uid := os.Getuid()
+	var pids []int
+	for _, e := range entries {
+		pid, err := strconv.Atoi(e.Name())
+		if err != nil {
+			continue
+		}
+		dir := filepath.Join(procRoot, e.Name())
+		if owner, ok := ownerOf(dir); !ok || owner != uid {
+			continue
+		}
+		if readTrimmed(filepath.Join(dir, "comm")) == comm {
+			pids = append(pids, pid)
+		}
+	}
+	sort.Ints(pids)
+	return pids
+}
+
+// signalAll sends sig to every process of this uid named comm, and answers the pids it reached.
+func signalAll(comm string, sig syscall.Signal) []int {
+	var reached []int
+	for _, pid := range processesOf(comm) {
+		if syscall.Kill(pid, sig) == nil {
+			reached = append(reached, pid)
+		}
+	}
+	return reached
+}

modules/feh/cmd/feh-tools/session_test.go

@@ -0,0 +1,174 @@
+package main
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"testing"
+	"time"
+)
+
+// fakeMachine points the session finder at a temporary /proc, /run/user and X socket directory, with
+// none of the test process's own session variables, and gives back the root.
+func fakeMachine(t *testing.T) string {
+	t.Helper()
+	root := t.TempDir()
+	procRoot, runUserDir, x11Sockets = filepath.Join(root, "proc"), filepath.Join(root, "run-user"), filepath.Join(root, "x11")
+	for _, d := range []string{procRoot, runUserDir, x11Sockets} {
+		if err := os.MkdirAll(d, 0o755); err != nil {
+			t.Fatal(err)
+		}
+	}
+	for _, k := range sessionKeys {
+		t.Setenv(k, "")
+	}
+	t.Setenv("MESH_OPERATOR_HOME", filepath.Join(root, "home"))
+	t.Cleanup(func() { procRoot, runUserDir, x11Sockets = "/proc", "/run/user", "/tmp/.X11-unix" })
+	return root
+}
+
+func fakeProcess(t *testing.T, pid int, comm string, env ...string) {
+	t.Helper()
+	dir := filepath.Join(procRoot, strconv.Itoa(pid))
+	if err := os.MkdirAll(dir, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(dir, "comm"), []byte(comm+"\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(dir, "environ"), []byte(strings.Join(env, "\x00")+"\x00"), 0o600); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestTheSessionIsReadFromTheWindowManagerBeforeAnyOtherProcess(t *testing.T) {
+	fakeMachine(t)
+	fakeProcess(t, 900, "xterm", "DISPLAY=:9", "XAUTHORITY=/elsewhere")
+	fakeProcess(t, 100, "i3", "DISPLAY=:1", "XAUTHORITY=/home/op/.Xauthority",
+		"DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/1000/bus", "XDG_SESSION_ID=3", "SECRET_TOKEN=never-copied")
+	fakeProcess(t, 50, "bash", "PATH=/usr/bin")
+	s, err := findSession()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if s.Display != ":1" || s.XAuthority != "/home/op/.Xauthority" || s.SessionID != "3" || !strings.Contains(s.From, "i3 (pid 100)") {
+		t.Fatalf("the window manager's environment: %+v", s)
+	}
+	for _, kv := range s.Env() {
+		if strings.HasPrefix(kv, "SECRET_TOKEN=") {
+			t.Fatal("a variable of the session process that is not a session variable was handed on")
+		}
+	}
+}
+
+func TestAnyProcessCarryingADisplayServesWhenTheWindowManagerIsNotFound(t *testing.T) {
+	fakeMachine(t)
+	fakeProcess(t, 10, "firefox", "DISPLAY=:0")
+	fakeProcess(t, 20, "firefox", "DISPLAY=:2")
+	s, err := findSession()
+	if err != nil || s.Display != ":2" {
+		t.Fatalf("the newest of two equals: %+v, %v", s, err)
+	}
+}
+
+func TestNoSessionIsAClearAnswerNotAGuess(t *testing.T) {
+	fakeMachine(t)
+	fakeProcess(t, 10, "sshd", "PATH=/usr/bin")
+	_, err := findSession()
+	if !errors.Is(err, ErrNoSession) || !strings.Contains(err.Error(), "logged in to the desktop") {
+		t.Fatalf("no session: %v", err)
+	}
+}
+
+func TestOneXSocketAndTheAccountsAuthorityFileAreASession(t *testing.T) {
+	root := fakeMachine(t)
+	if err := os.WriteFile(filepath.Join(x11Sockets, "X0"), nil, 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.MkdirAll(filepath.Join(root, "home"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(root, "home", ".Xauthority"), nil, 0o600); err != nil {
+		t.Fatal(err)
+	}
+	s, err := findSession()
+	if err != nil || s.Display != ":0" || !strings.HasSuffix(s.XAuthority, "/home/.Xauthority") {
+		t.Fatalf("socket and authority: %+v, %v", s, err)
+	}
+}
+
+func TestTheBusIsTheAccountsRuntimeDirectoryWhenNoProcessNamesIt(t *testing.T) {
+	fakeMachine(t)
+	runtime := filepath.Join(runUserDir, strconv.Itoa(os.Getuid()))
+	if _, err := findBus(); !errors.Is(err, ErrNoBus) {
+		t.Fatalf("no runtime directory is no bus: %v", err)
+	}
+	if err := os.MkdirAll(runtime, 0o700); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(runtime, "bus"), nil, 0o600); err != nil {
+		t.Fatal(err)
+	}
+	s, err := findBus()
+	if err != nil || s.Bus != "unix:path="+filepath.Join(runtime, "bus") || s.RuntimeDir != runtime {
+		t.Fatalf("bus: %+v, %v", s, err)
+	}
+	env := strings.Join(s.Env(), "\n")
+	if !strings.Contains(env, "XDG_RUNTIME_DIR="+runtime) || !strings.Contains(env, "DBUS_SESSION_BUS_ADDRESS=unix:path=") {
+		t.Fatalf("the bus is handed on: %s", env)
+	}
+}
+
+func TestACommandIsBoundedAndANonZeroExitIsAResult(t *testing.T) {
+	fakeMachine(t)
+	s := Session{}
+	r, err := s.run(5*time.Second, "in", "sh", "-c", "cat; echo err >&2; exit 3")
+	if err != nil || r.Stdout != "in" || r.Code != 3 || strings.TrimSpace(r.Stderr) != "err" {
+		t.Fatalf("result: %+v, %v", r, err)
+	}
+	start := time.Now()
+	if _, err := s.run(200*time.Millisecond, "", "sh", "-c", "sleep 30 & sleep 30"); err == nil || time.Since(start) > 5*time.Second {
+		t.Fatalf("a command past its time is ended with what it started: %v after %s", err, time.Since(start))
+	}
+	if _, err := s.run(time.Second, "", "no-such-program-here"); err == nil || !strings.Contains(err.Error(), "not installed") {
+		t.Fatalf("a missing program: %v", err)
+	}
+}
+
+func TestDetachAsksTheAccountsServiceManagerWithTheSessionsDisplay(t *testing.T) {
+	fakeMachine(t)
+	bin := fakeBinaries(t, map[string]string{
+		"systemctl":   `echo "systemctl $*" >> "$LOG"`,
+		"systemd-run": `echo "systemd-run $*" >> "$LOG"`,
+	})
+	log := filepath.Join(bin, "log")
+	t.Setenv("LOG", log)
+	s := Session{Display: ":1", XAuthority: "/x", RuntimeDir: "/run/user/1"}
+	if err := s.detach("picom-session", "picom", "--config", "/c"); err != nil {
+		t.Fatal(err)
+	}
+	got, _ := os.ReadFile(log)
+	want := "systemctl --user stop picom-session.service\n" +
+		"systemd-run --user --collect --quiet --unit=picom-session --setenv=DISPLAY=:1 --setenv=XAUTHORITY=/x -- picom --config /c\n"
+	if string(got) != want {
+		t.Fatalf("detach ran:\n%s\nwant:\n%s", got, want)
+	}
+	if err := (Session{}).detach("x", "y"); !errors.Is(err, ErrNoBus) {
+		t.Fatalf("no runtime directory: %v", err)
+	}
+}
+
+// fakeBinaries puts shell scripts named for programs first on PATH, and answers their directory.
+func fakeBinaries(t *testing.T, scripts map[string]string) string {
+	t.Helper()
+	dir := t.TempDir()
+	for name, body := range scripts {
+		if err := os.WriteFile(filepath.Join(dir, name), []byte("#!/bin/sh\n"+body+"\n"), 0o755); err != nil {
+			t.Fatal(err)
+		}
+	}
+	t.Setenv("PATH", dir+string(os.PathListSeparator)+os.Getenv("PATH"))
+	return dir
+}

modules/feh/cmd/feh-tools/wallpaper.go

@@ -0,0 +1,174 @@
+package main
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+	"time"
+)
+
+// modes are feh's background modes, by the word feh_set takes.
+var modes = []string{"fill", "center", "max", "scale", "tile"}
+
+// Wallpaper is images and how they are laid on the screens.
+type Wallpaper struct {
+	Images []string `json:"images"`
+	Mode   string   `json:"mode"`
+	At     string   `json:"at,omitempty"`
+}
+
+func fehbg() string { return filepath.Join(operatorHome(), ".fehbg") }
+
+// sessionRecord is where feh_set notes what it put up, for feh_current: in the runtime directory,
+// so it lasts exactly as long as the login, like the wallpaper itself.
+func sessionRecord(s Session) string {
+	if s.RuntimeDir == "" {
+		return ""
+	}
+	return filepath.Join(s.RuntimeDir, "feh", "current.json")
+}
+
+// SetResult is what feh_set answers.
+type SetResult struct {
+	Wallpaper
+	Note string `json:"note"`
+}
+
+// Set puts images up as the wallpaper for this session.
+func Set(images []string, mode string) (SetResult, error) {
+	if mode == "" {
+		mode = "fill"
+	}
+	known := false
+	for _, m := range modes {
+		known = known || m == mode
+	}
+	if !known {
+		return SetResult{}, fmt.Errorf("mode %q is one of %s", mode, strings.Join(modes, ", "))
+	}
+	if len(images) == 0 {
+		return SetResult{}, errors.New("images is required: at least one image")
+	}
+	var paths []string
+	for _, img := range images {
+		p := img
+		if strings.HasPrefix(p, "~/") {
+			p = filepath.Join(operatorHome(), p[2:])
+		}
+		if !filepath.IsAbs(p) {
+			p = filepath.Join(operatorHome(), p)
+		}
+		info, err := os.Stat(p)
+		if err != nil {
+			return SetResult{}, fmt.Errorf("image %s: %w", img, err)
+		}
+		if info.IsDir() {
+			return SetResult{}, fmt.Errorf("image %s is a directory", img)
+		}
+		paths = append(paths, p)
+	}
+	s, err := findSession()
+	if err != nil {
+		return SetResult{}, err
+	}
+	args := append([]string{"--no-fehbg", "--bg-" + mode}, paths...)
+	r, err := s.run(15*time.Second, "", "feh", args...)
+	if err != nil {
+		return SetResult{}, err
+	}
+	if r.Code != 0 {
+		return SetResult{}, fmt.Errorf("feh: %s", strings.TrimSpace(r.Stderr))
+	}
+	w := Wallpaper{Images: paths, Mode: mode, At: time.Now().Format(time.RFC3339)}
+	if rec := sessionRecord(s); rec != "" {
+		if err := os.MkdirAll(filepath.Dir(rec), 0o700); err == nil {
+			raw, _ := json.Marshal(w)
+			_ = os.WriteFile(rec, raw, 0o600)
+		}
+	}
+	return SetResult{Wallpaper: w, Note: "for this session; the declared wallpaper returns at the next login"}, nil
+}
+
+// CurrentResult is what feh_current answers.
+type CurrentResult struct {
+	Declared *Wallpaper `json:"declared"`
+	Session  *Wallpaper `json:"session,omitempty"`
+}
+
+var bgMode = regexp.MustCompile(`--bg-(fill|center|max|scale|tile)\b`)
+
+// Current is the declared wallpaper and the one set in this session.
+func Current() (CurrentResult, error) {
+	var out CurrentResult
+	if raw, err := os.ReadFile(fehbg()); err == nil {
+		out.Declared = parseFehbg(string(raw), operatorHome())
+	}
+	if rec := sessionRecord(findEnvironment()); rec != "" {
+		if raw, err := os.ReadFile(rec); err == nil {
+			var w Wallpaper
+			if json.Unmarshal(raw, &w) == nil {
+				out.Session = &w
+			}
+		}
+	}
+	return out, nil
+}
+
+// parseFehbg reads the feh line of a ~/.fehbg: its mode and its images, with $HOME expanded.
+func parseFehbg(script, home string) *Wallpaper {
+	for _, line := range strings.Split(script, "\n") {
+		line = strings.TrimSpace(line)
+		if !strings.HasPrefix(line, "feh ") {
+			continue
+		}
+		w := &Wallpaper{Images: []string{}}
+		if m := bgMode.FindStringSubmatch(line); m != nil {
+			w.Mode = m[1]
+		}
+		for _, word := range shellWords(line)[1:] {
+			if strings.HasPrefix(word, "-") {
+				continue
+			}
+			word = strings.ReplaceAll(strings.ReplaceAll(word, "${HOME}", home), "$HOME", home)
+			w.Images = append(w.Images, word)
+		}
+		return w
+	}
+	return nil
+}
+
+// shellWords splits a simple command line on blanks, honouring single and double quotes.
+func shellWords(line string) []string {
+	var words []string
+	var cur strings.Builder
+	var quote byte
+	in := false
+	for i := 0; i < len(line); i++ {
+		c := line[i]
+		switch {
+		case quote != 0 && c == quote:
+			quote = 0
+		case quote != 0:
+			cur.WriteByte(c)
+		case c == '\'' || c == '"':
+			quote, in = c, true
+		case c == ' ' || c == '\t':
+			if in {
+				words = append(words, cur.String())
+				cur.Reset()
+				in = false
+			}
+		default:
+			cur.WriteByte(c)
+			in = true
+		}
+	}
+	if in {
+		words = append(words, cur.String())
+	}
+	return words
+}