Run the router as its own account, ask unlinking of the linked account, and take no approval where an agent can become root (hq ADR 0259 §7, §8)

2026-10-09 17:08:17 +02:00
parent c2c75ceb3b
commit debb897c21
20 changed files with 937 additions and 111 deletions
@@ -36,9 +36,21 @@ channel's client and no channel's secret.
  linked an hour or more. The ask is then closed by compare-and-set — a second answer loses — and the
  warrant published to the asker alone. A warrant the bus did not take is published again every minute.
 - **An ask never defaults**: at its expiry it ends `expired` and its asker does what it said it would.
- **Linking** (`/start` to the bot): a six-digit code is shown on the desk for ten minutes, the operator
-  sends it to the bot, and the account is linked; it acknowledges at once and approves after an hour.
-  Every link and unlink is said on every channel. `messenger_unlink` unlinks.
+- **Linking** (`/start` to the bot): a six-digit code is shown, with the account's name and number, on a
+  channel whose words stay private (the desk) for ten minutes; the operator sends it to the bot, and the
+  account is linked. It acknowledges at once and approves after an hour. At most three links are asked of a
+  kind in an hour. Every link and unlink is said on every channel.
+- **Unlinking is asked of the account that is linked** (`messenger_unlink` asks it): an approve question put
+  to that account alone. Its approval unlinks it, told to it first, by name, then everywhere. **A link within
+  a day of an unlink waits for the replaced account's approval**, asked of it by name.
+- **When that account is lost with its phone**, root at the router's machine leaves a file in this module's
+  state directory — `unlink.<kind>`, or `allow-link.<kind>` for a link that waits — and the router does it,
+  announced as done at the machine. A file not made by root is refused and said.
+- **A channel proving its sender says only to the linked account**: none linked, it is not ready, and asks
+  for approval are not offered on it. While the controller says an agent can become root without a person
+  where the router or the channel runs (`agent-root`), no approval is offered or taken there.
+- **The router runs as its own account `messenger`, on a bus account of its own**, never carried by the
+  machine's runtime (ADR 0259 §8): its state and its bus credential are that account's.

 ## What is sent, and when

@@ -229,7 +229,17 @@ func (h *Holder) Failed(kind string, f asks.Failed) {
 			r.Pending = "raised"
 		}
 	}
+	desk := h.Bench != nil && h.Bench.roleOf(kind) == RoleDesk
 	h.mu.Unlock()
+	// A warning the desk could not show goes to the channel that reaches the operator away, as it did when the
+	// desk was the router's own (the correctness review of 2026-10-08).
+	if desk && r != nil && r.Cleared.IsZero() && r.Severity != Urgent && h.Away != nil && h.Away.Ready() == nil {
+		h.enqueue(h.Away.Name(), item{Key: r.Key, What: "raised", Severity: r.Severity, At: h.Now()})
+		h.mu.Lock()
+		r.Pending = ""
+		h.mu.Unlock()
+		h.flush(h.Now(), false)
+	}
 	outcome := "failed: " + f.Why
 	if f.Permanent {
 		outcome = "failed for good: " + f.Why
@@ -2,6 +2,9 @@ package main

 import (
 	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
 	"strings"
 	"testing"
 	"time"
@@ -14,16 +17,17 @@ import (

 // memAsks is the router's state in memory, with the compare-and-set the bus gives.
 type memAsks struct {
-	asks  map[string]AskRecord
-	revs  map[string]uint64
-	ids   map[string]Identity
-	links map[string]PendingLink
-	rev   uint64
+	asks     map[string]AskRecord
+	revs     map[string]uint64
+	ids      map[string]Identity
+	links    map[string]PendingLink
+	unlinked map[string]Unlinked
+	rev      uint64
 }

 func newMemAsks() *memAsks {
 	return &memAsks{asks: map[string]AskRecord{}, revs: map[string]uint64{}, ids: map[string]Identity{},
-		links: map[string]PendingLink{}}
+		links: map[string]PendingLink{}, unlinked: map[string]Unlinked{}}
 }

 func clone(r AskRecord) AskRecord {
@@ -89,6 +93,14 @@ func (m *memAsks) GetLink(kind string) (*PendingLink, error) {
 }
 func (m *memAsks) PutLink(kind string, l PendingLink) error { m.links[kind] = l; return nil }
 func (m *memAsks) DeleteLink(kind string) error             { delete(m.links, kind); return nil }
+func (m *memAsks) GetUnlinked(kind string) (*Unlinked, error) {
+	u, ok := m.unlinked[kind]
+	if !ok {
+		return nil, nil
+	}
+	return &u, nil
+}
+func (m *memAsks) PutUnlinked(kind string, u Unlinked) error { m.unlinked[kind] = u; return nil }

 // told is what the router published to askers, by subject.
 type told struct{ by map[string][]asks.Warrant }
@@ -104,9 +116,16 @@ func newRouter(t *testing.T) (*Holder, *fakeChannel, *fakeChannel, *clock, *memA
 	w := &told{by: map[string][]asks.Warrant{}}
 	bench := NewBench(c.now)
 	bench.SetKinds([]KindInfo{
-		{Kind: "telegram", Module: "telegram", Capabilities: []string{"deliver", "reaches-away", "choice", "edit", "verified-sender"}},
-		{Kind: "desktop", Module: "desk-channel", Capabilities: []string{"deliver", "choice", "edit"}},
+		{Kind: "telegram", Module: "telegram", Node: "anchor", Capabilities: []string{"deliver", "reaches-away", "choice", "edit",
+			"verified-sender", "exact-render"}},
+		{Kind: "desktop", Module: "desk-channel", Node: "anchor", Capabilities: []string{"deliver", "choice", "edit", "exact-render", "private"}},
 	})
+	bench.To = func(kind string) string {
+		if ids := h.identitiesOf(kind); len(ids) > 0 {
+			return ids[0].Identity
+		}
+		return ""
+	}
 	bench.Stand("telegram", Standing{Ready: true, At: c.now()})
 	bench.Stand("desktop", Standing{Ready: true, At: c.now()})
 	h.Bench, h.Asks = bench, store
@@ -198,16 +217,22 @@ func TestAnAskIsOfferedOnEachKindAsFarAsItCanCarryIt(t *testing.T) {
 }

 func TestWithoutALinkedAccountOnlyTheMeshMCPServerApproves(t *testing.T) {
-	h, tg, _, c, _, _ := newRouter(t)
+	h, tg, dt, c, _, _ := newRouter(t)
 	submit(t, h, "mesh-delivery", heldAsk(c, "d-1"))
-	c.pass(BurstWindow)
-	h.Flush()
-	if len(tg.sends) == 0 {
-		t.Fatal("nothing was said")
+	settle(h, c)
+	// Telegram says only to the account linked as the operator: none linked, it is not used at all.
+	if len(tg.sends) != 0 {
+		t.Errorf("an unlinked Telegram was sent %d messages", len(tg.sends))
 	}
-	m := tg.sends[0]
+	if err := h.Bench.Ready("telegram"); err == nil || !strings.Contains(err.Error(), "send /start to the bot") {
+		t.Errorf("an unlinked Telegram is ready: %v", err)
+	}
+	if len(dt.sends) == 0 {
+		t.Fatal("nothing was said on the desk")
+	}
+	m := dt.sends[0]
 	if got := labelsOf(m); got != "Silence for a week" || !strings.Contains(m.Body, "Release or Stop: from the mesh MCP server.") {
-		t.Errorf("telegram without a link offers %q and says %q", got, m.Body)
+		t.Errorf("the desk without a link offers %q and says %q", got, m.Body)
 	}
 }

@@ -561,13 +586,6 @@ func TestLinkingShowsACodeOnTheDeskAndLinksOnlyWhoAsked(t *testing.T) {
 	if _, pending := store.links["telegram"]; pending {
 		t.Error("a second link was begun while one is linked")
 	}
-	// Unlinking is said everywhere, and the account's answers are refused from then.
-	if _, err := h.Unlink("telegram"); err != nil {
-		t.Fatal(err)
-	}
-	if len(store.ids) != 0 || !strings.Contains(tg.sends[len(tg.sends)-1].Title, "No Telegram account is linked") {
-		t.Errorf("not unlinked and said: %v %q", store.ids, tg.sends[len(tg.sends)-1].Title)
-	}
 }

 func TestALinkCodeExpiresAndFiveWrongTriesEndIt(t *testing.T) {
@@ -591,3 +609,206 @@ func TestALinkCodeExpiresAndFiveWrongTriesEndIt(t *testing.T) {
 		t.Error("the desk began a link")
 	}
 }
+
+// novox/hq ADR 0259 §7 (revised): unlinking is an approve ask put to the account that is linked; its notice
+// reaches that account first, by name; nobody else's answer unlinks it.
+func TestUnlinkingIsAskedOfTheLinkedAccountAndToldToItFirst(t *testing.T) {
+	h, tg, dt, c, store, _ := newRouter(t)
+	link(h, store, c, "42", c.now().Add(-2*time.Hour))
+	got, err := h.Unlink("telegram")
+	if err != nil || got["asked"] != true {
+		t.Fatalf("%v %v", got, err)
+	}
+	if len(store.ids) != 1 {
+		t.Fatal("unlinked before the account answered")
+	}
+	ask := tg.sends[len(tg.sends)-1]
+	if ask.Title != "Urgent: Unlink this account?" || tg.to[len(tg.to)-1] != "42" || labelsOf(ask) != "Unlink" {
+		t.Fatalf("the question: %q to %q offers %q", ask.Title, tg.to[len(tg.to)-1], labelsOf(ask))
+	}
+	if last := dt.sends[len(dt.sends)-1]; !strings.Contains(last.Title, "An unlink of your Telegram account was asked") {
+		t.Errorf("the desk was not told: %q", last.Title)
+	}
+	unlink := ticketFor(ask, "Unlink")
+	// Another account cannot answer it.
+	if out, _ := h.Chosen("telegram", choiceOf(unlink, "666", c.now())); out != "refused" || len(store.ids) != 1 {
+		t.Fatalf("another account unlinked it: %s", out)
+	}
+	before := len(tg.sends)
+	if out, err := h.Chosen("telegram", choiceOf(unlink, "42", c.now())); err != nil || out != "chosen" {
+		t.Fatalf("%s %v", out, err)
+	}
+	if len(store.ids) != 0 {
+		t.Fatal("the account's own approval did not unlink it")
+	}
+	notice := tg.sends[before]
+	if notice.Title != "This account is no longer linked as you" || tg.to[before] != "42" {
+		t.Errorf("the account was not told first, by name: %q to %q", notice.Title, tg.to[before])
+	}
+	if last := dt.sends[len(dt.sends)-1]; !strings.Contains(last.Title, "No Telegram account is linked as you") {
+		t.Errorf("the desk was not told: %q", last.Title)
+	}
+}
+
+// A link within a day of an unlink waits for the replaced account's approval.
+func TestARelinkWithinADayWaitsForTheReplacedAccount(t *testing.T) {
+	h, tg, dt, c, store, _ := newRouter(t)
+	link(h, store, c, "42", c.now().Add(-2*time.Hour))
+	_, _ = h.Unlink("telegram")
+	_, _ = h.Chosen("telegram", choiceOf(ticketFor(tg.sends[len(tg.sends)-1], "Unlink"), "42", c.now()))
+	h.Link("telegram", asks.LinkAsked{ID: "l9", At: c.now(), Sender: asks.Sender{Identity: "666", Display: "Eve", Authenticated: true}})
+	code := codeOf(t, dt.sends[len(dt.sends)-1])
+	a := h.Prove("telegram", asks.Code{Sender: asks.Sender{Identity: "666", Authenticated: true}, Code: code})
+	if !a.Accepted || !strings.Contains(a.Words, "waits for that account's approval") || len(store.ids) != 0 {
+		t.Fatalf("linked at once within a day of an unlink: %+v %v", a, store.ids)
+	}
+	asked := tg.sends[len(tg.sends)-1]
+	if asked.Title != "Urgent: Allow another account in your place?" || tg.to[len(tg.to)-1] != "42" {
+		t.Fatalf("the replaced account was not asked: %q to %q", asked.Title, tg.to[len(tg.to)-1])
+	}
+	if out, _ := h.Chosen("telegram", choiceOf(ticketFor(asked, "Allow"), "666", c.now())); out != "refused" {
+		t.Error("the new account allowed itself")
+	}
+	if out, err := h.Chosen("telegram", choiceOf(ticketFor(asked, "Allow"), "42", c.now())); err != nil || out != "chosen" {
+		t.Fatalf("%s %v", out, err)
+	}
+	if id, ok := store.ids[identityKey("telegram", "666")]; !ok || id.ApproveFrom.Sub(id.Linked) != time.Hour {
+		t.Errorf("not linked on the replaced account's approval: %+v", store.ids)
+	}
+}
+
+// Root at the router's machine unlinks, or allows a waiting link, by a file only root makes.
+func TestBreakGlassIsAFileRootMade(t *testing.T) {
+	h, _, dt, c, store, _ := newRouter(t)
+	link(h, store, c, "42", c.now().Add(-2*time.Hour))
+	h.StateDir = t.TempDir()
+	if err := os.WriteFile(filepath.Join(h.StateDir, "unlink.telegram"), nil, 0o600); err != nil {
+		t.Fatal(err)
+	}
+	h.BreakGlass()
+	if len(store.ids) != 1 || !strings.Contains(dt.sends[len(dt.sends)-1].Title, "was refused") {
+		t.Fatalf("a file not made by root unlinked: %v", store.ids)
+	}
+	was := fileOwner
+	t.Cleanup(func() { fileOwner = was })
+	fileOwner = func(os.FileInfo) uint32 { return 0 }
+	_ = os.WriteFile(filepath.Join(h.StateDir, "unlink.telegram"), nil, 0o600)
+	h.BreakGlass()
+	if len(store.ids) != 0 {
+		t.Fatal("root's file did not unlink")
+	}
+	if _, err := os.Stat(filepath.Join(h.StateDir, "unlink.telegram")); err == nil {
+		t.Error("the file was left to act again")
+	}
+}
+
+// While an agent can become root where the router or the channel runs, nothing proven there approves.
+func TestNoApprovalWhileAnAgentCanBecomeRootThere(t *testing.T) {
+	h, tg, _, c, store, w := newRouter(t)
+	link(h, store, c, "42", c.now().Add(-2*time.Hour))
+	submit(t, h, "mesh-delivery", heldAsk(c, "d-1"))
+	settle(h, c)
+	release := ticketFor(tg.sends[0], "Release")
+	h.mu.Lock()
+	h.open["machine.anchor.agent-root"] = &Record{Key: "machine.anchor.agent-root", Kind: KindAgentRoot, Severity: Urgent,
+		Origin: "condition", Raised: c.now()}
+	h.mu.Unlock()
+	if out, err := h.Chosen("telegram", choiceOf(release, "42", c.now())); err == nil || out != "refused" ||
+		!strings.Contains(err.Error(), "can become root on anchor") {
+		t.Fatalf("approved while an agent can become root there: %s %v", out, err)
+	}
+	if len(w.of("mesh-delivery")) != 0 {
+		t.Error("a warrant was issued")
+	}
+	if got := h.carriers(asks.Approve); len(got) != 0 {
+		t.Errorf("an approval is still offered on %v", got)
+	}
+}
+
+// Another asker naming a condition's key does not take that condition's message over.
+func TestOnlyTheConditionsOwnerAsksOnItsMessage(t *testing.T) {
+	h, _, _, c, store, _ := newRouter(t)
+	k := cond("delivery.hq.held", Warning, "the delivery of hq is held")
+	k.Raised = c.now()
+	h.Condition(EventRaised, k)
+	a := heldAsk(c, "d-1")
+	a.About = "delivery.hq.held"
+	submit(t, h, "mesh-delivery", a)
+	if got := store.asks["mesh-delivery.d-1"].Record; got == "delivery.hq.held" {
+		t.Error("another asker took the condition's message")
+	}
+}
+
+// A channel that does not render exactly as the router does carries no answer.
+func TestAnAnswerNeedsAChannelThatRendersExactly(t *testing.T) {
+	h, _, _, c, _, _ := newRouter(t)
+	h.Bench.SetKinds([]KindInfo{{Kind: "desktop", Module: "desk-channel", Capabilities: []string{"deliver", "choice", "private"}}})
+	h.Bench.Stand("desktop", Standing{Ready: true, At: c.now()})
+	if got := h.carriers(asks.Acknowledge); len(got) != 0 {
+		t.Errorf("a channel without exact-render carries %v", got)
+	}
+}
+
+// At most three links an hour per kind, and the code is shown only where the words stay private.
+func TestLinksAreBoundedAndTheCodeShownOnlyInPrivate(t *testing.T) {
+	h, tg, dt, c, store, _ := newRouter(t)
+	jo := asks.Sender{Identity: "42", Display: "Jo", Authenticated: true}
+	for i := 0; i < LinksAnHour; i++ {
+		h.Link("telegram", asks.LinkAsked{ID: fmt.Sprint("l", i), At: c.now(), Sender: jo})
+	}
+	shown := len(dt.sends)
+	h.Link("telegram", asks.LinkAsked{ID: "l9", At: c.now(), Sender: jo})
+	if len(dt.sends) != shown || !strings.Contains(tg.sends[len(tg.sends)-1].Body, "Try again in an hour") {
+		t.Error("a fourth link this hour showed a code")
+	}
+	if !strings.Contains(dt.sends[0].Body, "(number 42)") {
+		t.Errorf("the notice does not name the account by its number: %q", dt.sends[0].Body)
+	}
+	h2, tg2, _, c2, store2, _ := newRouter(t)
+	h2.Bench.SetKinds([]KindInfo{
+		{Kind: "telegram", Module: "telegram", Capabilities: []string{"choice", "verified-sender", "exact-render", "reaches-away"}},
+		{Kind: "desktop", Module: "desk-channel", Capabilities: []string{"choice", "exact-render"}}})
+	h2.Link("telegram", asks.LinkAsked{ID: "l1", At: c2.now(), Sender: jo})
+	if _, pending := store2.links["telegram"]; pending || !strings.Contains(tg2.sends[len(tg2.sends)-1].Body, "No private place") {
+		t.Error("a code was shown where the words are not private")
+	}
+	_ = store
+}
+
+// A warning the desk could not show goes to the channel that reaches the operator away.
+func TestAWarningTheDeskCouldNotShowGoesAway(t *testing.T) {
+	h, tg, dt, c, store, _ := newRouter(t)
+	link(h, store, c, "42", c.now().Add(-2*time.Hour))
+	k := cond("module.x.unhealthy", Warning, "x is not healthy")
+	k.Raised = c.now()
+	h.Condition(EventRaised, k)
+	settle(h, c)
+	if len(dt.sends) != 1 {
+		t.Fatalf("the desk was sent %d", len(dt.sends))
+	}
+	h.Failed("desktop", asks.Failed{Handle: "g14=1", Why: "no session answers", At: c.now()})
+	c.pass(BurstWindow)
+	h.Flush()
+	if len(tg.sends) == 0 {
+		t.Error("a warning the desk could not show did not go to Telegram")
+	}
+}
+
+// codeOf reads the six digits a link's notice shows.
+func codeOf(t *testing.T, m Message) string {
+	t.Helper()
+	i := strings.Index(m.Body, ": ")
+	for i >= 0 {
+		rest := m.Body[i+2:]
+		if len(rest) >= 7 && rest[3] == ' ' {
+			return rest[:3] + rest[4:7]
+		}
+		j := strings.Index(rest, ": ")
+		if j < 0 {
+			break
+		}
+		i += 2 + j
+	}
+	t.Fatalf("no code in %q", m.Body)
+	return ""
+}
@@ -62,6 +62,11 @@ type AskRecord struct {
 	Told bool `json:"told,omitempty"`
 	// Record is the message the ask is shown on: a condition's key, or its own.
 	Record string `json:"record,omitempty"`
+	// Only is the one account that may answer it, on its kind: an ask of the router's own, put to the account
+	// an unlink or a relink concerns (novox/hq ADR 0259 §7).
+	Only *Identity `json:"only,omitempty"`
+	// Act is what the router does on its own ask's warrant: unlink, or link (selfact.go).
+	Act *SelfAct `json:"act,omitempty"`
 }

 // Identity is one account linked as the operator on a channel kind.
@@ -86,6 +91,8 @@ type AskStore interface {
 	GetLink(kind string) (*PendingLink, error)
 	PutLink(kind string, l PendingLink) error
 	DeleteLink(kind string) error
+	GetUnlinked(kind string) (*Unlinked, error)
+	PutUnlinked(kind string, u Unlinked) error
 }

 type askEntry struct {
@@ -161,14 +168,15 @@ func (h *Holder) carriers(level asks.Level) []string {
 	}
 	var out []string
 	for _, k := range h.Bench.Kinds() {
-		if h.Bench.Ready(k.Kind) != nil || !h.Bench.Promises(k.Kind, "choice") {
+		// Every level needs a choice made in one act, shown exactly as the router rendered it (ADR 0234 §8).
+		if h.Bench.Ready(k.Kind) != nil || !h.Bench.Promises(k.Kind, "choice") || !h.Bench.Promises(k.Kind, "exact-render") {
 			continue
 		}
 		switch level {
 		case asks.Acknowledge:
 			out = append(out, k.Kind)
 		case asks.Approve:
-			if h.Bench.Promises(k.Kind, "verified-sender") && h.linked(k.Kind) {
+			if h.Bench.Promises(k.Kind, "verified-sender") && h.linked(k.Kind) && h.rootFreeFor(k) == "" {
 				out = append(out, k.Kind)
 			}
 		}
@@ -177,6 +185,32 @@ func (h *Holder) carriers(level asks.Level) []string {
 	return out
 }

+// rootFreeFor is why a kind's proof is not believed now, or "": an agent can become root without a person
+// where the router or the kind's holder runs, which the controller's self-check says as an open condition
+// (novox/hq ADR 0259 §8, rule 2).
+func (h *Holder) rootFreeFor(k KindInfo) string {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	for _, r := range h.open {
+		if r.Kind != KindAgentRoot || !r.Cleared.IsZero() {
+			continue
+		}
+		machine := strings.TrimPrefix(strings.TrimSuffix(r.Key, "."+KindAgentRoot), "machine.")
+		if machine == k.Node || (h.Node != "" && machine == h.Node) {
+			return "a program working for you can become root on " + machine + " without asking you, so an answer " +
+				"proven there proves nothing until that changes"
+		}
+	}
+	return ""
+}
+
+// ConditionOwner is the module whose asks may be shown on a condition's message: the controller, which
+// raises the conditions.
+const ConditionOwner = "mesh-controller"
+
+// KindAgentRoot is the controller's condition while an agent can become root without a person on a machine.
+const KindAgentRoot = "agent-root"
+
 // TakeAsk takes one ask or cancel from the seat's queue. asker is the subject's last token, which the bus
 // grants that module alone. An error is returned only when the ask could not be recorded, so the queue
 // offers it again; a refusal is said to the asker and the work is taken.
@@ -257,8 +291,10 @@ func (h *Holder) TakeAsk(verb, asker string, body json.RawMessage) error {
 	// Shown on the condition it is about, when that is open here; otherwise as a message of its own.
 	h.mu.Lock()
 	target := h.open["ask."+key]
-	if a.About != "" {
-		if r := h.open[a.About]; r != nil && r.Cleared.IsZero() {
+	// Shown on a condition's message only when asked by the condition's owner: another asker naming a
+	// condition's key does not take its message over.
+	if a.About != "" && asker == ConditionOwner {
+		if r := h.open[a.About]; r != nil && r.Cleared.IsZero() && r.Origin == "condition" {
 			target = r
 		}
 	}
@@ -416,6 +452,13 @@ func (h *Holder) closeAsk(key string, outcome asks.Outcome, words string, w *ask
 		rev = newRev
 	}
 	h.keepAsk(key, rec, rev)
+	if rec.Asker == SelfAsker {
+		// The router's own ask: it does what was decided, and tells nobody else (selfact.go).
+		h.markTold(key)
+		h.showClosed(rec)
+		h.selfAct(rec, *w)
+		return nil
+	}
 	if h.tell(*w) == nil {
 		h.markTold(key)
 	}
@@ -590,7 +633,7 @@ func (h *Holder) judge(kind string, c asks.Choice, key string) (string, error) {
 		return h.refuseChoice(kind, c, "it names an answer the question does not offer")
 	}
 	info, held := h.Bench.Kind(kind)
-	if !held || !h.Bench.Promises(kind, "choice") {
+	if !held || !h.Bench.Promises(kind, "choice") || !h.Bench.Promises(kind, "exact-render") {
 		return h.refuseChoice(kind, c, "this channel is not one the mesh holds for answers")
 	}
 	person := asks.Person{Who: asks.Operator, Kind: kind, Identity: c.Sender.Identity, Display: c.Sender.Display}
@@ -601,6 +644,14 @@ func (h *Holder) judge(kind string, c asks.Choice, key string) (string, error) {
 			return h.refuseChoice(kind, c, "the service did not authenticate who sent it")
 		}
 		id = h.identity(kind, c.Sender.Identity)
+		if rec.Only != nil {
+			// An ask put to one account is answered by that account alone, linked or not any more.
+			if rec.Only.Kind != kind || rec.Only.Identity != c.Sender.Identity {
+				return h.refuseChoice(kind, c, "this question was put to another account")
+			}
+			only := *rec.Only
+			id = &only
+		}
 		if id == nil {
 			return h.refuseChoice(kind, c, "this account is not linked as the operator")
 		}
@@ -619,6 +670,9 @@ func (h *Holder) judge(kind string, c asks.Choice, key string) (string, error) {
 			return h.refuseChoice(kind, c, "this account was linked at "+id.Linked.In(h.zone()).Format("15:04")+
 				" and can approve from "+id.ApproveFrom.In(h.zone()).Format("15:04"))
 		}
+		if why := h.rootFreeFor(info); why != "" {
+			return h.refuseChoice(kind, c, why)
+		}
 		proofs = append(proofs, "P1")
 	default:
 		return h.refuseChoice(kind, c, "it needs a code from the authenticator app, which the mesh does not take yet")
@@ -645,6 +699,30 @@ func (h *Holder) refuseChoice(kind string, c asks.Choice, why string) (string, e
 	return "refused", errorf("%s", why)
 }

+// showOnHandle is showOn, answering the handle the message is known by.
+func (h *Holder) showOnHandle(kind string, m Message) (string, error) {
+	for _, ch := range h.channels() {
+		if ch.Name() == kind {
+			id, err := ch.Send(m)
+			h.noteChannel(kind, err)
+			return id, err
+		}
+	}
+	if h.Publish == nil {
+		return "", errors.New("this router cannot reach the bus")
+	}
+	out := asks.Message{Handle: newHandle(), Title: m.Title, Body: m.Body, Urgent: m.Urgent, Silent: m.Quiet, Reply: m.Reply, To: m.To}
+	if out.To == "" && h.Bench != nil && h.Bench.To != nil {
+		out.To = h.Bench.To(kind)
+	}
+	for _, a := range m.Actions {
+		out.Buttons = append(out.Buttons, asks.Button{Label: a.Label, Ticket: a.Token})
+	}
+	err := h.Publish(asks.ChannelSubject(asks.Show, kind), out, out.Handle)
+	h.noteChannel(kind, err)
+	return out.Handle, err
+}
+
 // showOn says a message of the router's own on one kind, at once: an answer's refusal, details, a link's code.
 func (h *Holder) showOn(kind string, m Message) error {
 	for _, ch := range h.channels() {
@@ -661,6 +739,12 @@ func (h *Holder) showOn(kind string, m Message) error {
 	if h.Bench != nil && h.Bench.To != nil {
 		out.To = h.Bench.To(kind)
 	}
+	if m.To != "" {
+		out.To = m.To
+	}
+	for _, a := range m.Actions {
+		out.Buttons = append(out.Buttons, asks.Button{Label: a.Label, Ticket: a.Token})
+	}
 	err := h.Publish(asks.ChannelSubject(asks.Send, kind), out, out.Handle)
 	h.noteChannel(kind, err)
 	return err
@@ -91,6 +91,9 @@ type Message struct {
 	Actions []Choice
 	// Reply is the answer this message answers, by its id: the channel shows it where that was given.
 	Reply string
+	// To is the account it is for, when not the one linked: a notice to an account being unlinked, or an
+	// ask put to the account a relink replaces.
+	To string
 }

 // Choice is one answer a message offers: the token a channel hands back when it is chosen, and its label.
@@ -229,8 +232,12 @@ type Holder struct {
 	Asks    AskStore
 	Bench   *Bench
 	Publish func(subject string, body any, id string) error
-	Now     func() time.Time
-	Logf    func(string, ...any)
+	// Node is the machine this router runs on; StateDir its own directory, where root leaves a break-glass
+	// request (selfact.go).
+	Node     string
+	StateDir string
+	Now      func() time.Time
+	Logf     func(string, ...any)
 	// Emit states a fact as this module (refused); nil states nothing.
 	Emit func(event string, body any) error
 	// Ask calls a seat verb through the mesh, as this module: the answers the operator chooses.
@@ -270,6 +277,9 @@ type Holder struct {
 	// asks are the asks this router holds, by `<asker>.<id>`, and tickets each ask's tickets to it.
 	asks    map[string]*askEntry
 	tickets map[string]string
+	// linksAsked are when links were asked, by kind, for the hourly bound; lastUnlink the last unlink of each.
+	linksAsked map[string][]time.Time
+	lastUnlink map[string]Unlinked
 }

 func (h *Holder) init() {
@@ -551,6 +561,7 @@ func (h *Holder) Tick() {
 	h.mu.Unlock()
 	sort.Slice(recs, func(i, j int) bool { return recs[i].Raised.Before(recs[j].Raised) })
 	h.sweepAsks(now)
+	h.BreakGlass()
 	for _, r := range recs {
 		switch {
 		case !r.Cleared.IsZero():
@@ -9,6 +9,7 @@ import (
 )

 type fakeChannel struct {
+	to       []string // whom each send was for, by account; "" for the linked one
 	name     string
 	notReady error
 	fail     error
@@ -29,6 +30,7 @@ func (f *fakeChannel) Send(m Message) (string, error) {
 	}
 	f.n++
 	f.sends = append(f.sends, m)
+	f.to = append(f.to, m.To)
 	if f.name == "desktop" {
 		return fmt.Sprintf("g14=%d", f.n), nil // as the desktop answers: the machine and the notification
 	}
@@ -49,6 +49,8 @@ type PendingLink struct {
 	CodeHash string    `json:"code-hash"`
 	Expires  time.Time `json:"expires"`
 	Tries    int       `json:"tries"`
+	// Confirmed: the code was right, and the link waits for the account it replaces.
+	Confirmed bool `json:"confirmed,omitempty"`
 }

 func identityKey(kind, identity string) string { return kind + "." + kvKey(identity) }
@@ -93,7 +95,11 @@ func (h *Holder) identitiesOf(kind string) []Identity {

 func (h *Holder) linked(kind string) bool { return len(h.identitiesOf(kind)) > 0 }

-// Link takes a link asked for on a kind: a code shown on the desk, or a refusal said on the kind.
+// LinksAnHour is how many links may be asked of one kind in an hour.
+const LinksAnHour = 3
+
+// Link takes a link asked for on a kind: a code shown where only the operator sees it, or a refusal said on
+// the kind.
 func (h *Holder) Link(kind string, l asks.LinkAsked) string {
 	h.work.Lock()
 	defer h.work.Unlock()
@@ -107,7 +113,8 @@ func (h *Holder) Link(kind string, l asks.LinkAsked) string {
 	if !l.Sender.Authenticated || l.Sender.Identity == "" {
 		return reply("Not linked", "The service did not say who you are.")
 	}
-	if now := h.Now(); now.Sub(l.At) > FreshFor {
+	now := h.Now()
+	if now.Sub(l.At) > FreshFor {
 		h.Logf("[messenger] a link asked on %s at %s is too old to act on", kind, l.At.Format(time.RFC3339))
 		return "too old"
 	}
@@ -115,10 +122,38 @@ func (h *Holder) Link(kind string, l asks.LinkAsked) string {
 		if id.Identity == l.Sender.Identity {
 			return reply("Already linked", "This account is already linked as the operator.")
 		}
-		return reply("Another account is linked", "Another account is linked as the operator here. It is unlinked from the mesh MCP server (messenger_unlink), and then this one can be linked.")
+		return reply("Another account is linked", "Another account is linked as the operator here. It is unlinked "+
+			"with that account's own approval, and then this one can be linked.")
 	}
-	if h.Desk == nil || h.Desk.Ready() != nil {
-		return reply("Not linked", "No desk can show the code now. Try again when you are at your machine.")
+	h.mu.Lock()
+	if h.linksAsked == nil {
+		h.linksAsked = map[string][]time.Time{}
+	}
+	var recent []time.Time
+	for _, t := range h.linksAsked[kind] {
+		if now.Sub(t) < time.Hour {
+			recent = append(recent, t)
+		}
+	}
+	full := len(recent) >= LinksAnHour
+	if !full {
+		recent = append(recent, now)
+	}
+	h.linksAsked[kind] = recent
+	h.mu.Unlock()
+	if full {
+		return reply("Not linked", fmt.Sprintf("Links were asked %d times this hour. Try again in an hour.", LinksAnHour))
+	}
+	// A code is shown only where the words stay on the operator's machines: a kind declaring `private`.
+	shows := ""
+	for _, k := range h.Bench.Kinds() {
+		if k.Kind != kind && h.Bench.Promises(k.Kind, "private") && h.Bench.Ready(k.Kind) == nil {
+			shows = k.Kind
+			break
+		}
+	}
+	if shows == "" {
+		return reply("Not linked", "No private place can show the code now. Try again when you are at your machine.")
 	}
 	code, err := sixDigits()
 	if err != nil {
@@ -126,7 +161,7 @@ func (h *Holder) Link(kind string, l asks.LinkAsked) string {
 	}
 	salt := ticket()
 	p := PendingLink{Kind: kind, Identity: l.Sender.Identity, Display: l.Sender.Display, Salt: salt,
-		CodeHash: hashCode(salt, code), Expires: h.Now().Add(LinkCodeFor)}
+		CodeHash: hashCode(salt, code), Expires: now.Add(LinkCodeFor)}
 	if err := h.Asks.PutLink(kind, p); err != nil {
 		return reply("Not linked", "The link could not be recorded: "+err.Error())
 	}
@@ -134,16 +169,16 @@ func (h *Holder) Link(kind string, l asks.LinkAsked) string {
 	if who == "" {
 		who = "an account"
 	}
-	desk := Message{Title: "Link a " + Display(kind) + " account as you",
-		Body: fmt.Sprintf("The %s account %q asked to be linked as you. If that is you, send this code to the bot "+
-			"before %s: %s %s. If it is not you, do nothing: nothing is linked.", Display(kind), who,
-			p.Expires.In(h.zone()).Format("15:04"), code[:3], code[3:]),
+	notice := Message{Title: "Link a " + Display(kind) + " account as you",
+		Body: fmt.Sprintf("The %s account %q (number %s) asked to be linked as you. If that is you, send this code to "+
+			"the bot before %s: %s %s. If it is not you, do nothing: nothing is linked.", Display(kind), who,
+			l.Sender.Identity, p.Expires.In(h.zone()).Format("15:04"), code[:3], code[3:]),
 		Urgent: true}
-	if _, err := h.Desk.Send(desk); err != nil {
+	if err := h.showOn(shows, notice); err != nil {
 		_ = h.Asks.DeleteLink(kind)
-		return reply("Not linked", "The desk could not show the code: "+err.Error())
+		return reply("Not linked", "The code could not be shown: "+err.Error())
 	}
-	h.Logf("[messenger] a link was asked on %s by %q; its code is shown on the desk", kind, who)
+	h.Logf("[messenger] a link was asked on %s by %q (%s); its code is shown on %s", kind, who, l.Sender.Identity, shows)
 	return reply("Send the code shown on your desk", "Six digits, within ten minutes.")
 }

@@ -159,8 +194,8 @@ func (h *Holder) Prove(kind string, c asks.Code) asks.ProofAnswer {
 		return no("Nothing can be linked here.")
 	}
 	p, err := h.Asks.GetLink(kind)
-	if err != nil || p == nil {
-		return no("No link was asked for. Send /start to begin.")
+	if err != nil || p == nil || p.Confirmed {
+		return no("No link waits for a code. Send /start to begin.")
 	}
 	now := h.Now()
 	if !now.Before(p.Expires) {
@@ -181,44 +216,32 @@ func (h *Holder) Prove(kind string, c asks.Code) asks.ProofAnswer {
 		_ = h.Asks.PutLink(kind, *p)
 		return no("That code is not right.")
 	}
-	id := Identity{Kind: kind, Identity: p.Identity, Display: p.Display, Linked: now, ApproveFrom: now.Add(LinkedApproveAfter)}
-	if err := h.Asks.PutIdentity(identityKey(kind, p.Identity), id); err != nil {
-		return no("The link could not be recorded: " + err.Error())
-	}
-	_ = h.Asks.DeleteLink(kind)
-	from := id.ApproveFrom.In(h.zone()).Format("15:04")
-	h.announce(Message{Title: "A " + Display(kind) + " account is now linked as you",
-		Body: fmt.Sprintf("The %s account %q can answer acknowledgements now, and approve from %s. If this was not "+
-			"you, unlink it from the mesh MCP server (messenger_unlink) before then.", Display(kind), p.Display, from),
-		Urgent: true})
-	h.record(Sent{At: now, Channel: kind, Key: "(link)", What: "linked " + p.Display, Outcome: "linked"})
-	h.Logf("[messenger] linked %q on %s; it approves from %s", p.Display, kind, from)
-	return asks.ProofAnswer{Accepted: true, Words: "Linked. You can answer acknowledgements now, and approve from " + from + "."}
-}
-
-// Unlink removes every account linked on a kind, said on every channel.
-func (h *Holder) Unlink(kind string) (map[string]any, error) {
-	h.work.Lock()
-	defer h.work.Unlock()
-	if h.Asks == nil {
-		return nil, errorf("nothing is linked here")
-	}
-	ids := h.identitiesOf(kind)
-	if len(ids) == 0 {
-		return map[string]any{"kind": kind, "unlinked": []string{}}, nil
-	}
-	var names []string
-	for _, id := range ids {
-		if err := h.Asks.DeleteIdentity(identityKey(kind, id.Identity)); err != nil {
-			return nil, err
+	id := Identity{Kind: kind, Identity: p.Identity, Display: p.Display}
+	if u := h.recentUnlink(kind); u != nil && u.Identity.Identity != p.Identity {
+		// Within a day of an unlink: the account it replaces decides (novox/hq ADR 0259 §7).
+		p.Confirmed = true
+		p.Expires = now.Add(RelinkWaits)
+		_ = h.Asks.PutLink(kind, *p)
+		a := asks.Ask{ID: "relink-" + kind + "-" + fmt.Sprint(now.Unix()),
+			Headline: "Allow another account in your place?",
+			Explanation: fmt.Sprintf("This account was unlinked from being you less than a day ago. The %s account %s "+
+				"(number %s) now asks to be linked as you. If you choose Allow, it is.", Display(kind), p.Display, p.Identity),
+			Who: asks.Operator, Expires: now.Add(RelinkWaits - time.Minute), OnExpiry: "nothing is linked",
+			Options: []asks.Option{{ID: "allow", Label: "Allow", Does: "the other account is linked as you", Level: asks.Approve}}}
+		prior := u.Identity
+		prior.ApproveFrom = prior.Linked // an account linked before: its hour passed while it was linked
+		if err := h.askSelf(a, prior, SelfAct{Do: "link", Kind: kind, Link: &id}); err != nil {
+			return no("The link could not be asked of the account it replaces: " + err.Error())
 		}
-		names = append(names, id.Display)
+		h.announce(Message{Title: "A new " + Display(kind) + " account asks to be linked as you",
+			Body: fmt.Sprintf("%s (number %s), less than a day after an unlink. It waits for the account it replaces, "+
+				"or for root at the router's machine.", p.Display, p.Identity), Urgent: true})
+		return asks.ProofAnswer{Accepted: true, Words: "The code is right. Because an account was unlinked here less " +
+			"than a day ago, the link waits for that account's approval, or for you at the router's machine."}
 	}
-	h.announce(Message{Title: "No " + Display(kind) + " account is linked as you any more",
-		Body: "Unlinked: " + strings.Join(names, ", ") + ". Answers that need you to be proven cannot be given on " +
-			Display(kind) + " until an account is linked again.", Urgent: true})
-	h.record(Sent{At: h.Now(), Channel: kind, Key: "(link)", What: "unlinked", Outcome: strings.Join(names, ", ")})
-	return map[string]any{"kind": kind, "unlinked": names}, nil
+	h.linkNow(id, "with the code shown on the desk")
+	from := now.Add(LinkedApproveAfter).In(h.zone()).Format("15:04")
+	return asks.ProofAnswer{Accepted: true, Words: "Linked. You can answer acknowledgements now, and approve from " + from + "."}
 }

 // Identities is every linked account, by kind.
@@ -126,9 +126,9 @@ func (stateStore) Recent() ([]Sent, error) {
 // `identities` (novox/hq ADR 0259). Each write that must win once is a compare-and-set.
 type askStore struct{}

-// changed reads the runtime's refusal of a compare-and-set that lost as ErrChanged.
+// changed reads the runtime's refusal of a compare-and-set that lost, told by its code, as ErrChanged.
 func changed(err error) error {
-	if err != nil && strings.Contains(err.Error(), "written by another writer first") {
+	if errors.Is(err, stdio.ErrChanged) {
 		return ErrChanged
 	}
 	return err
@@ -171,7 +171,7 @@ func (askStore) IdentityKeys() ([]string, error) {
 	keys, err := stdio.State("identities").Keys()
 	var out []string
 	for _, k := range keys {
-		if !strings.HasPrefix(k, "pending.") {
+		if !strings.HasPrefix(k, "pending.") && !strings.HasPrefix(k, "unlinked.") {
 			out = append(out, k)
 		}
 	}
@@ -192,6 +192,18 @@ func (askStore) PutLink(kind string, l PendingLink) error {
 func (askStore) DeleteLink(kind string) error {
 	return stdio.State("identities").Delete("pending." + kind)
 }
+func (askStore) GetUnlinked(kind string) (*Unlinked, error) {
+	e, err := stdio.State("identities").Get("unlinked." + kind)
+	if err != nil || e == nil {
+		return nil, err
+	}
+	var u Unlinked
+	return &u, json.Unmarshal(e.Value, &u)
+}
+func (askStore) PutUnlinked(kind string, u Unlinked) error {
+	_, err := stdio.State("identities").Put("unlinked."+kind, u)
+	return err
+}

 // listening is whether condition events reach this holder, in words.
 type listening struct {
@@ -222,14 +234,16 @@ func main() {
 	bench := NewBench(time.Now)
 	publish := func(subject string, body any, id string) error { return stdio.SeatPublish(subject, body, id) }
 	h := &Holder{
-		Away:    &SeatChannel{Bench: bench, Role: RoleAway, Publish: publish},
-		Desk:    &SeatChannel{Bench: bench, Role: RoleDesk, Publish: publish},
-		Store:   stateStore{},
-		Asks:    askStore{},
-		Bench:   bench,
-		Publish: publish,
-		Ask:     stdio.Ask,
-		Logf:    logf,
+		Away:     &SeatChannel{Bench: bench, Role: RoleAway, Publish: publish},
+		Desk:     &SeatChannel{Bench: bench, Role: RoleDesk, Publish: publish},
+		Store:    stateStore{},
+		Asks:     askStore{},
+		Node:     os.Getenv("MESH_NODE"),
+		StateDir: os.Getenv("MESH_MESSENGER_STATE"),
+		Bench:    bench,
+		Publish:  publish,
+		Ask:      stdio.Ask,
+		Logf:     logf,
 		Zone: func() *time.Location {
 			loc, err := zoneOf(settings().TimeZone)
 			said.Lock()
@@ -18,17 +18,19 @@ import (
 // no channel's secret, and names nothing of one installation.

 type manifest struct {
-	Module   string `json:"module"`
-	Seats    []seat `json:"seats"`
-	Claims   []seat `json:"claims"`
-	Uses     []string
-	Consumes []string
-	Emits    []string
-	Invokes  []string
-	State    []json.RawMessage
-	Own      map[string]string `json:"own-secrets"`
-	Tools    []string
-	Build    struct {
+	Module       string `json:"module"`
+	Seats        []seat `json:"seats"`
+	Claims       []seat `json:"claims"`
+	Uses         []string
+	Consumes     []string
+	Emits        []string
+	Invokes      []string
+	State        []json.RawMessage
+	Own          map[string]string `json:"own-secrets"`
+	RunsAs       string            `json:"runs-as"`
+	SecretsOwner string            `json:"secrets-owner"`
+	Tools        []string
+	Build        struct {
 		Artifacts []map[string]any `json:"artifacts"`
 	} `json:"build"`
 }
@@ -99,8 +101,9 @@ func TestItDeclaresTheSeatsOfAnAskAndHoldsTheOperatorChannel(t *testing.T) {
 	if !reflect.DeepEqual(state, []string{"open", "sent", "asks", "identities"}) {
 		t.Fatalf("state %v", state)
 	}
-	if len(m.Own) != 0 {
-		t.Fatalf("it holds a channel's secret: %v", m.Own)
+	// It holds no channel's secret: only its own bus account, read by its own account alone (ADR 0259 §8).
+	if len(m.Own) != 1 || m.Own["broker"] == "" || m.RunsAs != "messenger" || m.SecretsOwner != "messenger" {
+		t.Fatalf("own secrets %v, runs as %q, secrets owned by %q", m.Own, m.RunsAs, m.SecretsOwner)
 	}
 }

@@ -137,6 +137,10 @@ func (b *Bench) Ready(kind string) error {
 			return fmt.Errorf("%s says it cannot send", kind)
 		}
 		return errors.New(s.Why)
+	case b.Promises(kind, "verified-sender") && b.To != nil && b.To(kind) == "":
+		// A channel proving its sender says only to the account linked as the operator: none linked, it has
+		// nobody to say anything to (the correctness review of 2026-10-08).
+		return fmt.Errorf("no %s account is linked as the operator: send /start to the bot", Display(kind))
 	}
 	return nil
 }
@@ -255,6 +259,9 @@ func (c *SeatChannel) putOn(kind, handle string, m Message, edit bool) error {
 	if c.Bench.To != nil {
 		out.To = c.Bench.To(kind)
 	}
+	if m.To != "" {
+		out.To = m.To
+	}
 	for _, a := range m.Actions {
 		out.Buttons = append(out.Buttons, asks.Button{Label: a.Label, Ticket: a.Token})
 	}
@@ -0,0 +1,247 @@
+package main
+
+// The router's own asks (novox/hq ADR 0259 §7, as revised after the security review of 2026-10-08): who the
+// operator is on a channel changes only with the word of the account it is now.
+//
+//   - **Unlinking is an approve ask, put to the account that is linked.** Whoever could unlink the
+//     operator's account without it could link their own in its place. The notice of the unlink reaches that
+//     account first, by name, and then every channel.
+//   - **A link within a day of an unlink waits for the replaced account's approval**, asked of it by name.
+//   - **When that account is lost with its phone**, the operator, as root at the router's machine, leaves a
+//     file in the router's directory — `unlink.<kind>` or `allow-link.<kind>`, owned by root — and the router
+//     does it, announced as done at the machine. A file of any other owner is refused and said: an agent
+//     without root cannot make one.
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"syscall"
+	"time"
+
+	"git.novox.be/novox/mesh-sdk/go/asks"
+)
+
+// SelfAsker is the name the router asks its own questions under.
+const SelfAsker = "messenger"
+
+// RelinkWaits is how long after an unlink a new link waits for the replaced account's approval.
+const RelinkWaits = 24 * time.Hour
+
+// SelfAct is what the router does on its own ask's warrant.
+type SelfAct struct {
+	Do   string    `json:"do"` // "unlink" or "link"
+	Kind string    `json:"kind"`
+	Link *Identity `json:"link,omitempty"` // the account a link makes the operator's
+}
+
+// Unlinked is the last account unlinked on a kind, kept a day so a relink is asked of it.
+type Unlinked struct {
+	Identity Identity  `json:"identity"`
+	At       time.Time `json:"at"`
+}
+
+// askSelf puts a question of the router's own to one account, on its kind, and keeps it like any ask.
+func (h *Holder) askSelf(a asks.Ask, only Identity, act SelfAct) error {
+	key := askKey(SelfAsker, a.ID)
+	now := h.Now()
+	rec := AskRecord{Asker: SelfAsker, Ask: a, State: StateOpen, Opened: now, Tickets: map[string]Ticket{},
+		Only: &only, Act: &act, Record: "ask." + key}
+	for _, o := range a.Options {
+		rec.Tickets[ticket()] = Ticket{Option: o.ID, Kind: only.Kind}
+	}
+	if h.Asks != nil {
+		rev, err := h.Asks.CreateAsk(key, rec)
+		if err != nil {
+			return err
+		}
+		h.keepAsk(key, rec, rev)
+	} else {
+		h.keepAsk(key, rec, 0)
+	}
+	r := Record{Key: rec.Record, Kind: "ask", Subject: SelfAsker, Severity: Urgent, Summary: a.Headline,
+		Headline: a.Headline, Explanation: a.Explanation, Origin: "ask", More: "operator-channel.asks",
+		Raised: now, Sent: map[string]string{}, Seen: now, Count: 1, Ask: key}
+	h.mu.Lock()
+	h.open[r.Key] = &r
+	h.mu.Unlock()
+	m := h.words(&r, "raised")
+	m.Actions = h.offers(&rec, only.Kind)
+	m.To = only.Identity
+	handle, err := h.showOnHandle(only.Kind, m)
+	if err == nil {
+		h.mu.Lock()
+		r.Sent[only.Kind] = handle
+		r.FirstSent = now
+		h.mu.Unlock()
+	}
+	h.persist(&r)
+	return err
+}
+
+// selfAct does what the router's own ask decided.
+func (h *Holder) selfAct(rec AskRecord, w asks.Warrant) {
+	if rec.Act == nil || w.Outcome != asks.OutcomeChosen {
+		return
+	}
+	switch rec.Act.Do {
+	case "unlink":
+		h.unlinkNow(rec.Act.Kind, "approved by the account itself")
+	case "link":
+		if rec.Act.Link != nil {
+			h.linkNow(*rec.Act.Link, "approved by the account it replaces")
+		}
+	}
+}
+
+// Unlink asks the account linked on a kind whether it is to be unlinked: an approve ask put to it alone.
+func (h *Holder) Unlink(kind string) (map[string]any, error) {
+	h.work.Lock()
+	defer h.work.Unlock()
+	ids := h.identitiesOf(kind)
+	if len(ids) == 0 {
+		return map[string]any{"kind": kind, "linked": false, "asked": false}, nil
+	}
+	id := ids[0]
+	now := h.Now()
+	a := asks.Ask{ID: "unlink-" + kind + "-" + fmt.Sprint(now.Unix()), Headline: "Unlink this account?",
+		Explanation: fmt.Sprintf("Unlinking this %s account (%s, number %s) was asked. If you choose Unlink, answers "+
+			"from here stop counting as yours until an account is linked again.", Display(kind), id.Display, id.Identity),
+		Who: asks.Operator, Expires: now.Add(time.Hour), OnExpiry: "the account stays linked",
+		Options: []asks.Option{{ID: "unlink", Label: "Unlink", Does: "this account stops answering as you", Level: asks.Approve}}}
+	if err := h.askSelf(a, id, SelfAct{Do: "unlink", Kind: kind}); err != nil {
+		return nil, err
+	}
+	h.announceExcept(kind, Message{Title: "An unlink of your " + Display(kind) + " account was asked",
+		Body: fmt.Sprintf("It waits for the account itself (%s, number %s) to approve it within the hour. If you "+
+			"cannot answer there, you unlink it as root at the router's machine.", id.Display, id.Identity), Urgent: true})
+	return map[string]any{"kind": kind, "asked": true, "of": id.Display}, nil
+}
+
+// unlinkNow unlinks a kind's account: told first, by name, then every channel.
+func (h *Holder) unlinkNow(kind, how string) {
+	ids := h.identitiesOf(kind)
+	if len(ids) == 0 || h.Asks == nil {
+		return
+	}
+	id := ids[0]
+	_ = h.showOn(kind, Message{Title: "This account is no longer linked as you",
+		Body: "Unlinked, " + how + ". Answers from here no longer count as yours.", Urgent: true, To: id.Identity})
+	if err := h.Asks.DeleteIdentity(identityKey(kind, id.Identity)); err != nil {
+		h.Logf("[messenger] the unlink of %s on %s could not be recorded: %v", id.Display, kind, err)
+		return
+	}
+	h.unlinked(kind, Unlinked{Identity: id, At: h.Now()})
+	h.announce(Message{Title: "No " + Display(kind) + " account is linked as you any more",
+		Body: fmt.Sprintf("Unlinked: %s (number %s), %s. A new link within a day waits for that account's approval.",
+			id.Display, id.Identity, how), Urgent: true})
+	h.record(Sent{At: h.Now(), Channel: kind, Key: "(link)", What: "unlinked", Outcome: id.Display + ", " + how})
+}
+
+// linkNow links an account as the operator's: acknowledges at once, approves after the hour.
+func (h *Holder) linkNow(id Identity, how string) {
+	if h.Asks == nil {
+		return
+	}
+	now := h.Now()
+	id.Linked, id.ApproveFrom = now, now.Add(LinkedApproveAfter)
+	if err := h.Asks.PutIdentity(identityKey(id.Kind, id.Identity), id); err != nil {
+		h.Logf("[messenger] the link of %s on %s could not be recorded: %v", id.Display, id.Kind, err)
+		return
+	}
+	_ = h.Asks.DeleteLink(id.Kind)
+	from := id.ApproveFrom.In(h.zone()).Format("15:04")
+	h.announce(Message{Title: "A " + Display(id.Kind) + " account is now linked as you",
+		Body: fmt.Sprintf("The %s account %s (number %s) is linked, %s. It can answer acknowledgements now, and "+
+			"approve from %s. If this was not you, unlink it before then.", Display(id.Kind), id.Display, id.Identity, how, from),
+		Urgent: true})
+	h.record(Sent{At: now, Channel: id.Kind, Key: "(link)", What: "linked " + id.Display, Outcome: how})
+}
+
+// BreakGlass does what root asked at the router's machine: a file `unlink.<kind>` or `allow-link.<kind>` in the
+// router's directory, owned by root. Called every minute.
+func (h *Holder) BreakGlass() {
+	if h.StateDir == "" {
+		return
+	}
+	for _, pattern := range []string{"unlink.*", "allow-link.*"} {
+		files, _ := filepath.Glob(filepath.Join(h.StateDir, pattern))
+		for _, f := range files {
+			name := filepath.Base(f)
+			what, kind, _ := strings.Cut(name, ".")
+			info, err := os.Lstat(f)
+			if err != nil {
+				continue
+			}
+			owner := fileOwner(info)
+			_ = os.Remove(f)
+			if !info.Mode().IsRegular() || owner != 0 {
+				h.Logf("[messenger] %s was refused: it is not a file root made", name)
+				h.announce(Message{Title: "A request to change who is you was refused",
+					Body:   "A file asking it was left at the router's machine by someone other than root. Nothing changed.",
+					Urgent: true})
+				continue
+			}
+			h.work.Lock()
+			switch what {
+			case "unlink":
+				h.unlinkNow(kind, "at the router's machine, as root")
+			case "allow-link":
+				if p, err := h.Asks.GetLink(kind); err == nil && p != nil && p.Confirmed {
+					h.linkNow(Identity{Kind: kind, Identity: p.Identity, Display: p.Display}, "allowed at the router's machine, as root")
+				}
+			}
+			h.work.Unlock()
+		}
+	}
+}
+
+// fileOwner is the uid owning a file; a variable so a test, which is not root, can stand for root.
+var fileOwner = func(info os.FileInfo) uint32 {
+	if st, ok := info.Sys().(*syscall.Stat_t); ok {
+		return st.Uid
+	}
+	return 1
+}
+
+// unlinked keeps the last unlink of a kind, a day.
+func (h *Holder) unlinked(kind string, u Unlinked) {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	if h.lastUnlink == nil {
+		h.lastUnlink = map[string]Unlinked{}
+	}
+	h.lastUnlink[kind] = u
+	if h.Asks != nil {
+		_ = h.Asks.PutUnlinked(kind, u)
+	}
+}
+
+// recentUnlink is the account unlinked on a kind less than a day ago, if any.
+func (h *Holder) recentUnlink(kind string) *Unlinked {
+	h.mu.Lock()
+	u, ok := h.lastUnlink[kind]
+	h.mu.Unlock()
+	if !ok && h.Asks != nil {
+		if got, err := h.Asks.GetUnlinked(kind); err == nil && got != nil {
+			u, ok = *got, true
+		}
+	}
+	if !ok || h.Now().Sub(u.At) >= RelinkWaits {
+		return nil
+	}
+	return &u
+}
+
+// announceExcept says a message on every kind that can send but one.
+func (h *Holder) announceExcept(kind string, m Message) {
+	if h.Bench == nil {
+		return
+	}
+	for _, k := range h.Bench.Kinds() {
+		if k.Kind != kind && h.Bench.Ready(k.Kind) == nil {
+			_ = h.showOn(k.Kind, m)
+		}
+	}
+}
@@ -314,3 +314,34 @@ func TestTimesAreSaidInTheOperatorsZone(t *testing.T) {
 		t.Errorf("a zone that does not exist was not said: %v", err)
 	}
 }
+
+// A warning kept quiet is said once after a day, and not again (novox/hq ADR 0258 §6).
+func TestAQuietWarningIsSaidOnceAfterADay(t *testing.T) {
+	h, tg, dt, c, _ := newHolder(t)
+	c.t = time.Date(2026, 10, 8, 10, 40, 0, 0, time.UTC)
+	e := examples[0]
+	raised, _ := DecodeCondition(EventRaised, e.event(c.now(), false))
+	h.Condition(EventRaised, raised)
+	settle(h, c)
+	if len(dt.sends)+len(tg.sends) != 0 {
+		t.Fatal("said while it needed nothing")
+	}
+	c.pass(QuietRemindAfter - time.Hour)
+	h.Tick()
+	settle(h, c)
+	if len(dt.sends)+len(tg.sends) != 0 {
+		t.Fatal("said before a day")
+	}
+	c.pass(time.Hour)
+	h.Tick()
+	settle(h, c)
+	if len(dt.sends) != 1 || !strings.HasPrefix(dt.sends[0].Title, "Still open after a day: ") {
+		t.Fatalf("not said once after a day: %+v", dt.sends)
+	}
+	c.pass(QuietRemindAfter)
+	h.Tick()
+	settle(h, c)
+	if len(dt.sends) != 1 {
+		t.Errorf("said again: %d", len(dt.sends))
+	}
+}
@@ -2,4 +2,4 @@ module messenger

 go 1.22

-require git.novox.be/novox/mesh-sdk/go v0.1.8-0.20261008145004-62367ce15ad6
+require git.novox.be/novox/mesh-sdk/go v0.1.8-0.20261008162031-55090da7e08f
@@ -6,3 +6,5 @@ git.novox.be/novox/mesh-sdk/go v0.1.8-0.20261008144136-2f2840488818 h1:o0yf4yyH8
 git.novox.be/novox/mesh-sdk/go v0.1.8-0.20261008144136-2f2840488818/go.mod h1:GFuZUElBZ9A++mxgIKo97aXXo+kV0uJ/UkbhQPPIbrY=
 git.novox.be/novox/mesh-sdk/go v0.1.8-0.20261008145004-62367ce15ad6 h1:JT7xM1bnLNInW7/oImV2OlXTrcQ4/GSM0Y8tAb+AhmY=
 git.novox.be/novox/mesh-sdk/go v0.1.8-0.20261008145004-62367ce15ad6/go.mod h1:GFuZUElBZ9A++mxgIKo97aXXo+kV0uJ/UkbhQPPIbrY=
+git.novox.be/novox/mesh-sdk/go v0.1.8-0.20261008162031-55090da7e08f h1:BNvyWq899GwP7F3sY4ACieB5a5fnFAq+sJ9lP6HQ5qI=
+git.novox.be/novox/mesh-sdk/go v0.1.8-0.20261008162031-55090da7e08f/go.mod h1:GFuZUElBZ9A++mxgIKo97aXXo+kV0uJ/UkbhQPPIbrY=
@@ -2,6 +2,7 @@
  "module": "messenger",
  "version": "1",
  "slug": "msgr",
+  "runs-as": "messenger",
  "seats": [
    {
      "name": "operator-channel",
@@ -92,6 +93,10 @@
    },
    "identities"
  ],
+  "own-secrets": {
+    "broker": "${dir:state}/broker"
+  },
+  "secrets-owner": "messenger",
  "tools": [
    "messenger_status",
    "messenger_recent",
@@ -101,11 +106,19 @@
    "messenger_unlink"
  ],
  "resources": [
+    {
+      "id": "account",
+      "type": "user",
+      "name": "messenger",
+      "shell": "/usr/bin/nologin",
+      "home": "/var/lib/messenger"
+    },
    {
      "id": "state",
      "type": "directory",
      "mode": "0700",
-      "place": "."
+      "place": ".",
+      "owner": "messenger"
    },
    {
      "id": "settings",
@@ -113,7 +126,8 @@
      "path": "${dir:state}/settings.json",
      "mode": "0600",
      "merge": "json",
-      "content": "{\n  \"time-zone\": \"\"\n}\n"
+      "content": "{\n  \"time-zone\": \"\"\n}\n",
+      "owner": "messenger"
    }
  ],
  "build": {
@@ -129,7 +143,8 @@
          "messenger"
        ],
        "env": {
-          "MESH_MESSENGER_SETTINGS": "${dir:state}/settings.json"
+          "MESH_MESSENGER_SETTINGS": "${dir:state}/settings.json",
+          "MESH_MESSENGER_STATE": "${dir:state}"
        }
      }
    ]
@@ -0,0 +1,89 @@
+package main
+
+// Who can become root here without a person (novox/hq ADR 0259 §8): the controller's self-check asks it of
+// every machine where the router or a channel proving its sender runs, for the accounts agents run as and
+// the account the machine's runtime runs commands as.
+//
+// Root without a person is any of: a sudo rule letting the account run every command as root with no
+// password; membership of a group that is root by another name (docker, which mounts the host; disk, which
+// reads it raw; wheel or sudo only where a rule grants them without a password, which the listing shows); or
+// the account being root itself.
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+)
+
+// Escalation is one account's answer.
+type Escalation struct {
+	Account string `json:"account"`
+	Root    bool   `json:"root_without_a_person"`
+	Why     string `json:"why"`
+}
+
+// rootGroups are groups that are root by another name.
+var rootGroups = map[string]string{"docker": "the docker group, which can mount the machine's root file system",
+	"disk": "the disk group, which reads and writes the drives raw", "root": "the root group"}
+
+var accountShape = regexp.MustCompile(`^[a-z_][a-z0-9_-]{0,31}$`)
+
+// Escalations answers, for each account, whether it can become root here without a person.
+func (m *Machine) Escalations(accounts []string) ([]Escalation, error) {
+	if len(accounts) == 0 {
+		return nil, fmt.Errorf("name the accounts to judge")
+	}
+	var out []Escalation
+	for _, a := range accounts {
+		if !accountShape.MatchString(a) {
+			return nil, fmt.Errorf("%q is not an account name", a)
+		}
+		out = append(out, m.escalation(a))
+	}
+	return out, nil
+}
+
+func (m *Machine) escalation(account string) Escalation {
+	e := Escalation{Account: account}
+	if account == "root" {
+		e.Root, e.Why = true, "it is root"
+		return e
+	}
+	id := m.Run(bg(), "id", "-nG", account)
+	if id.Status != 0 || id.Err != "" {
+		e.Why = "no such account here"
+		return e
+	}
+	for _, g := range strings.Fields(id.Stdout) {
+		if why, ok := rootGroups[g]; ok {
+			e.Root, e.Why = true, "a member of "+why
+			return e
+		}
+	}
+	// sudo's own word, for that account: listing another account's rules needs root, which the runtime's
+	// account escalates to as the mesh's acting tools do.
+	r := m.Run(bg(), "sudo", "-n", "-l", "-U", account)
+	if r.Status != 0 || r.Err != "" {
+		if strings.Contains(r.Stdout+r.Stderr, "not allowed to run sudo") {
+			e.Why = "no sudo rule names it"
+			return e
+		}
+		e.Why = "sudo could not be asked: " + strings.TrimSpace(firstLine(r.Stderr+r.Err))
+		return e
+	}
+	if strings.Contains(r.Stdout, "is not allowed to run sudo") {
+		e.Why = "no sudo rule names it"
+		return e
+	}
+	rules := ParseList(r.Stdout, account)
+	if rules.PasswordlessAll {
+		for _, rule := range rules.Rules {
+			if hasTag(rule.Tags, "NOPASSWD") && contains(rule.Commands, "ALL") && runsAsRoot(rule.RunAs) {
+				e.Root, e.Why = true, "sudo lets it run every command as root without a password ("+rule.Line+")"
+				return e
+			}
+		}
+	}
+	e.Why = "sudo asks it for a password, or lets it run named commands only"
+	return e
+}
@@ -0,0 +1,34 @@
+package main
+
+import (
+	"strings"
+	"testing"
+)
+
+// novox/hq ADR 0259 §8: who can become root here without a person, as the self-check asks it.
+func TestWhoCanBecomeRootWithoutAPerson(t *testing.T) {
+	var calls []call
+	run := byLine(map[string]Ran{
+		"id -nG ops":            {Stdout: "ops wheel\n"},
+		"sudo -n -l -U ops":     {Stdout: "User ops may run the following commands on anchor:\n    (ALL : ALL) NOPASSWD: ALL\n"},
+		"id -nG agents":         {Stdout: "agents\n"},
+		"sudo -n -l -U agents":  {Stdout: "User agents is not allowed to run sudo on anchor.\n"},
+		"id -nG builder":        {Stdout: "builder docker\n"},
+		"id -nG careful":        {Stdout: "careful wheel\n"},
+		"sudo -n -l -U careful": {Stdout: "User careful may run the following commands on anchor:\n    (ALL : ALL) ALL\n"},
+		"id -nG ghost":          {Status: 1, Stderr: "id: 'ghost': no such user"},
+	}, &calls)
+	got, err := machine(run, 1000).Escalations([]string{"ops", "agents", "builder", "careful", "ghost", "root"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := map[string]bool{"ops": true, "agents": false, "builder": true, "careful": false, "ghost": false, "root": true}
+	for _, e := range got {
+		if e.Root != want[e.Account] || e.Why == "" {
+			t.Errorf("%s: root %v (%s), want %v", e.Account, e.Root, e.Why, want[e.Account])
+		}
+	}
+	if _, err := machine(run, 1000).Escalations([]string{"a b"}); err == nil || !strings.Contains(err.Error(), "not an account name") {
+		t.Errorf("an account name that is not one was asked: %v", err)
+	}
+}
@@ -44,6 +44,26 @@ func tools(m *Machine) []stdio.Tool {
 			Input: schema(map[string]any{}),
 			Run:   func(map[string]any) (any, error) { return m.CheckEscalation() },
 		},
+		{
+			Name: "sudo_escalation",
+			Description: "Can these accounts become root on this machine without a person: a sudo rule running every " +
+				"command as root with no password, or a group that is root by another name (docker, disk). Each " +
+				"account with yes or no and why. Asked by the self-check where the router or a channel proving its " +
+				"sender runs (novox/hq ADR 0259).",
+			Input: schema(map[string]any{"accounts": map[string]any{"type": "array", "items": map[string]any{"type": "string"},
+				"description": "the accounts to judge"}}),
+			Run: func(a map[string]any) (any, error) {
+				var accounts []string
+				if list, ok := a["accounts"].([]any); ok {
+					for _, x := range list {
+						if s, ok := x.(string); ok {
+							accounts = append(accounts, s)
+						}
+					}
+				}
+				return m.Escalations(accounts)
+			},
+		},
 		{
 			Name: "sudo_drop_ins",
 			Description: "The files of /etc/sudoers.d with owner, mode and size, whether sudo reads each (a name with a dot " +
@@ -7,6 +7,7 @@
  "tools": [
    "sudo_rules",
    "sudo_check",
+    "sudo_escalation",
    "sudo_drop_ins"
  ],
  "resources": [