One message per problem: a reminder replaces, a blip says nothing (issues 373 and 369)

The operator stopped believing the mesh's notifications: one problem stood
twice on the desk (a reminder beside the message it followed, an escalation
then a reminder 31 s later), a unit failing again at each apply was said
again 22 times, and a question's buttons outlived it on a reminder the
ask's end never reached.

- messenger: a reminder or escalation is said in place of the problem's
  message (Replace under its handle), alone, never as a digest line; a
  problem first said in a digest gets its own message next time. A
  reminder counts from when it was last said. A clearing is said once it
  stays cleared 2 min (10 min once it came back); back before that, the
  message continues without a word. Cleared before ever said and back:
  said. An ask's expiry is said with its day.
- desk-channel: a send or show under a handle already shown replaces its
  notification by the notifier's replace id.
- telegram: the same deletes the earlier message and sends the new one,
  ringing as its kind rings; one it cannot delete loses its buttons.

modules/desk-channel/README.md

@@ -11,6 +11,10 @@ each machine the operator sits at (the `node-notifier` seat), and says which but
   was made. A message with buttons stays until it is dismissed.
 - **A notifier that started again** (`dunst.started`) is shown again every open message with buttons it showed.
 - A message no machine took is said to the router as failed; the router tries it again.
+- **One notification per message** (issue 373): an `edit`, and a `send` or `show` under a handle already shown (a
+  reminder, an escalation), replace that message's notification on each machine by its id (the notifier's
+  `replace_id`), so a problem is one notification updated in place. An edit goes only where it was shown; a
+  message said again is shown anew on a machine it was not.
 
 ## What the operator gives
 

modules/desk-channel/cmd/desk-channel/desk.go

@@ -141,8 +141,13 @@ func (d *Desk) Take(subject string, body json.RawMessage) error {
 			machines = []string{on}
 		}
 	}
+	// **One notification per message** (issue 373): an edit, and a message said again under a handle already
+	// shown (a reminder, an escalation), replace the notification it had on each machine — dunst's replace id —
+	// so a problem is one notification updated in place, never one more beside it. An edit stays quiet where
+	// it was shown; a message said again is shown anew where it was not.
+	edit := parts[4] == asks.Edit
 	var before *Shown
-	if parts[4] == asks.Edit {
+	if edit || !m.Secret {
 		var err error
 		if before, err = d.Store.Get(m.Handle); err != nil {
 			return err
@@ -154,7 +159,7 @@ func (d *Desk) Take(subject string, body json.RawMessage) error {
 		replace := 0
 		if before != nil {
 			replace = before.On[machine]
-			if replace == 0 {
+			if edit && replace == 0 {
 				continue // an edit goes where the message was shown, and nowhere new
 			}
 		}

modules/desk-channel/cmd/desk-channel/desk_test.go

@@ -259,3 +259,42 @@ func TestItRunsAsItsOwnAccount(t *testing.T) {
 		t.Errorf("the account %v, its state %v, its settings %v", account, state, settings)
 	}
 }
+
+// Issue 373: a message said again under its handle (a reminder, an escalation) replaces its notification on
+// each machine — the notifier is called with that notification's replace id — and is shown anew only where it
+// was not shown; a message under a new handle replaces nothing.
+func TestAMessageSaidAgainUnderItsHandleReplacesItsNotification(t *testing.T) {
+	d, shown, _, store := newDesk(t, "laptop", "desktop")
+	take(t, d, asks.Send, asks.Message{Handle: "m1", Title: "2 failed services on shanks"})
+	take(t, d, asks.Send, asks.Message{Handle: "m2", Title: "another problem"})
+	if len(*shown) != 4 {
+		t.Fatalf("shown %d", len(*shown))
+	}
+	for _, n := range *shown {
+		if _, has := n.args["replace_id"]; has {
+			t.Fatalf("a new message replaced a notification: %+v", n)
+		}
+	}
+	first := store["m1"].On
+	// The desk now names a third machine as well.
+	d.Machines = func() []string { return []string{"laptop", "desktop", "third"} }
+	take(t, d, asks.Show, asks.Message{Handle: "m1", Title: "Still open: 2 failed services on shanks", Urgent: true,
+		Buttons: []asks.Button{{Label: "Silence for a week", Ticket: "t1"}}})
+	again := (*shown)[4:]
+	if len(again) != 3 {
+		t.Fatalf("said again on %d machines", len(again))
+	}
+	for _, n := range again {
+		want, was := first[n.machine]
+		got, replaces := n.args["replace_id"]
+		switch {
+		case was && (!replaces || got != want):
+			t.Errorf("on %s the reminder did not replace notification %d: %v", n.machine, want, n.args)
+		case !was && replaces:
+			t.Errorf("on %s, where it was not shown, it replaced %v", n.machine, got)
+		}
+	}
+	if s := store["m1"]; len(s.On) != 3 || len(s.Message.Buttons) != 1 {
+		t.Fatalf("what is shown was not kept: %+v", s)
+	}
+}

modules/messenger/README.md

@@ -114,12 +114,21 @@ warning kept quiet is also said once after a day.
 | When | What |
 |---|---|
 | `condition-raised` | one message, deduplicated by the condition's key |
-| still open after 1 h (urgent) or 12 h (warning) | once more — never sooner than that after it was first said |
-| `condition-changed` from warning to urgent | once more, to both channels |
-| `condition-cleared` | the first message edited to say so; said inside a digest, a line in the next one |
-| cleared and raised again within 10 min | the same message, edited back to open — not a new one |
+| still open after 1 h (urgent) or 12 h (warning) | once more, in place of its message — never sooner than that after it was last said |
+| `condition-changed` from warning to urgent | once more, in place of its message, to both channels |
+| `condition-cleared` | once it stays cleared 2 min (10 min once it came back): its message edited to say so; said inside a digest, a line in the next one |
+| cleared and raised again before its clearing was said | nothing: to the operator it never ended — a unit failing again after each apply is one message, not one per apply |
+| cleared, said so, and raised again within 10 min | the same message, edited back to open — not a new one |
 | silenced | nothing, its clearing included |
 
+**One message per problem** (issue 373). A record keeps the id of its message on each channel; a reminder or
+an escalation is said **in place of it** — the channel takes the earlier one away and shows the new one as a
+new message is shown, so it rings once and no second message stands beside the first (the desk replaces the
+notification by its id; Telegram deletes the earlier message). A message said again goes alone, never as a
+line of a digest beside the message it follows; one first said inside a digest gets a message of its own the
+next time, and later words replace or edit that one. An ask's buttons live on that one message, so an ask that
+ends takes them away everywhere; its expiry is said with its day when it is not today.
+
 - **Routing:** urgent to every kind that can send; a warning to the desk where it can send, otherwise to
   the channel that reaches the operator away; an ask to every kind that carries one of its answers.
 - **Bursts are one message.** What is to be said on a channel is held **30 s** from the first and goes

modules/messenger/cmd/messenger/details_test.go

@@ -11,6 +11,15 @@ import (
 // open message", because each new message replaced the ticket of the one before it. Every message still
 // shown keeps a Details of its own, used once, and Details never acts.
 
+// shownOn is every message a channel was given: sent, or said again in place of an earlier one (issue 373).
+func shownOn(ch *fakeChannel) []Message {
+	out := append([]Message(nil), ch.sends...)
+	for _, r := range ch.replaced {
+		out = append(out, r.m)
+	}
+	return out
+}
+
 func detailsOf(t *testing.T, m Message) string {
 	t.Helper()
 	tok := ticketFor(m, DetailsLabel)
@@ -47,10 +56,13 @@ func TestDetailsWorksOnEachOfThreeWarningsOnceEach(t *testing.T) {
 					settle(h, c)
 				}
 			}
-			if len(tg.sends) != 3 {
-				t.Fatalf("%d messages, want 3", len(tg.sends))
+			// Issue 373: one problem said again replaces its message rather than standing beside it; each of
+			// the three messages still has a Details of its own.
+			msgs := shownOn(tg)
+			if len(msgs) != 3 {
+				t.Fatalf("%d messages, want 3", len(msgs))
 			}
-			for _, m := range tg.sends {
+			for _, m := range msgs {
 				toks = append(toks, detailsOf(t, m))
 			}
 			if toks[0] == toks[1] || toks[1] == toks[2] || toks[0] == toks[2] {
@@ -188,10 +200,11 @@ func TestAnUnreadyChannelPushesOutNoShownDetails(t *testing.T) {
 	tg.notReady = nil
 	c.pass(2 * time.Minute)
 	h.Flush()
-	if len(tg.sends) != 2 {
-		t.Fatalf("%d messages, want 2", len(tg.sends))
+	msgs := shownOn(tg)
+	if len(msgs) != 2 {
+		t.Fatalf("%d messages, want 2", len(msgs))
 	}
-	for _, tk := range []string{tok, detailsOf(t, tg.sends[1])} {
+	for _, tk := range []string{tok, detailsOf(t, msgs[1])} {
 		if out, err := h.Chosen("telegram", choiceOf(tk, "42", c.now())); err != nil || out != "shown" {
 			t.Errorf("Details: %q %v", out, err)
 		}

modules/messenger/cmd/messenger/history_test.go

@@ -292,7 +292,7 @@ func TestABurstIsOneMessage(t *testing.T) {
 	for i := 0; i < 3; i++ {
 		h.Condition(EventCleared, Condition{Key: fmt.Sprintf("seat.s%d.silent", i)})
 	}
-	runFor(h, c, time.Minute)
+	runFor(h, c, ClearSettle+time.Minute) // a clearing is said once it stays cleared (issue 373)
 	if len(tg.sends) != 2 || len(tg.edits) != 0 || !strings.HasPrefix(tg.sends[1].Title, "Mesh: 3 resolved") {
 		t.Fatalf("sends %d edits %d: %q", len(tg.sends), len(tg.edits), tg.sends[len(tg.sends)-1].Title)
 	}

modules/messenger/cmd/messenger/holder.go

@@ -25,9 +25,11 @@ package main
 //
 //   - On `condition-raised`: one message, deduplicated by the condition's key. Said again with the
 //     same key while open, it is the same message, not a second.
-//   - Once more if still open after 1 hour (urgent) or 12 hours (warning).
-//   - On `condition-cleared`: the first message is edited where the channel can (both can).
-//     Cleared and raised again within ten minutes, it is the same message, edited back to open.
+//   - Once more if still open after 1 hour (urgent) or 12 hours (warning), counted from when it was last
+//     said; a reminder or an escalation replaces its message, never stands beside it (issue 373).
+//   - On `condition-cleared`: once it stays cleared ClearSettle, its message is edited where the channel can
+//     (both can). Raised again before that, nothing is said: to the operator it never ended. Cleared, said
+//     so, and raised again within ten minutes, it is the same message, edited back to open.
 //   - A silenced condition sends nothing.
 //   - Urgent to both channels; warning to the desktop when the operator's session is there,
 //     otherwise to Telegram.
@@ -59,9 +61,13 @@ const (
 	// QuietRemindAfter: a warning kept quiet as needing nothing is said once after this.
 	QuietRemindAfter = 24 * time.Hour
 	ReopenWindow     = 10 * time.Minute
-	CapPerHour       = 20
-	KeptSends        = 200
-	KeptRefusals     = 50
+	// ClearSettle: a clearing is said once the condition stayed cleared this long. One raised again sooner
+	// (a unit failing again after each apply, issue 373) continues its message without a word, and its
+	// clearing is never said. Once it has come back, its next clearing waits the whole ReopenWindow.
+	ClearSettle  = 2 * time.Minute
+	CapPerHour   = 20
+	KeptSends    = 200
+	KeptRefusals = 50
 
 	// FreshFor: an event older than this by its own time is history — state, never a message.
 	FreshFor = 10 * time.Minute
@@ -120,6 +126,18 @@ type Channel interface {
 	CanEdit() bool
 }
 
+// replacer is a channel that can say a message again in place of the one it showed under that id: the earlier
+// one goes, the new one is shown as a new message is — it rings as its kind rings (issue 373). A reminder or
+// an escalation is then one message per problem, never one more beside it.
+type replacer interface {
+	Replace(id string, m Message) error
+}
+
+func replaces(ch Channel) bool {
+	_, ok := ch.(replacer)
+	return ok
+}
+
 // silentEditor is a channel whose edits notify nobody (Telegram's are): what is over is said there
 // even when it ended while the holder was away, since saying it costs the operator nothing.
 type silentEditor interface{ SilentEdit() bool }
@@ -160,14 +178,22 @@ type Record struct {
 	More         string            `json:"more"`
 	Raised       time.Time         `json:"raised"`
 	SilencedTill time.Time         `json:"silenced_till,omitempty"`
-	Sent         map[string]string `json:"sent,omitempty"` // channel -> the first message's id; "" when said in a digest
+	Sent         map[string]string `json:"sent,omitempty"` // channel -> its message's id; "" when said in a digest
 	FirstSent    time.Time         `json:"first_sent,omitempty"`
-	Reminded     bool              `json:"reminded,omitempty"`
-	Pending      string            `json:"pending,omitempty"` // what could not be said yet: raised, reminder, …
-	Folded       bool              `json:"folded,omitempty"`  // held by the cap
-	Cleared      time.Time         `json:"cleared,omitempty"`
-	Count        int               `json:"count"`
-	Refused      string            `json:"refused,omitempty"`
+	// LastSaid is when a message about it last went out: a reminder is due its bound after it, never sooner
+	// (an escalation followed by a reminder 31 s later, issue 373).
+	LastSaid time.Time `json:"last_said,omitempty"`
+	// ClearUnsaid: cleared, and the clearing not said yet — it is said once it stays cleared ClearSettle;
+	// raised again before, the message continues as if it never cleared. ClearSilent: said only where an edit
+	// notifies nobody (it ended while this holder was away).
+	ClearUnsaid bool      `json:"clear_unsaid,omitempty"`
+	ClearSilent bool      `json:"clear_silent,omitempty"`
+	Reminded    bool      `json:"reminded,omitempty"`
+	Pending     string    `json:"pending,omitempty"` // what could not be said yet: raised, reminder, …
+	Folded      bool      `json:"folded,omitempty"`  // held by the cap
+	Cleared     time.Time `json:"cleared,omitempty"`
+	Count       int       `json:"count"`
+	Refused     string    `json:"refused,omitempty"`
 	// History: known from the state or from an old event, and never said — not news.
 	History bool `json:"history,omitempty"`
 	// Seen is when this holder last took word of it; the open set read after it is authoritative.
@@ -454,14 +480,27 @@ func (h *Holder) raised(rec Record, quiet bool) {
 	if old != nil && now.Sub(old.Cleared) < ReopenWindow {
 		// Cleared and raised again within ten minutes: the same message, back to open (to-be 45 §2).
 		h.mu.Lock()
+		blip := old.ClearUnsaid
+		gone := now.Sub(old.Cleared)
 		old.Cleared = time.Time{}
+		old.ClearUnsaid, old.ClearSilent = false, false
 		old.Count++
 		old.Summary, old.Severity, old.SilencedTill = rec.Summary, rec.Severity, rec.SilencedTill
 		old.takeWords(rec)
 		old.Seen = now
 		h.mu.Unlock()
-		if !quiet && !old.silenced(now) && old.told() {
+		switch {
+		case quiet || old.silenced(now):
+		case blip:
+			// Its clearing was never said (issue 373): to the operator it never ended, so nothing is said now.
+			h.Logf("[messenger] %s back %s after it cleared, which was not said yet: the same message continues, nothing said",
+				old.Key, roughly(gone))
+			h.record(Sent{At: now, Channel: "-", Key: old.Key, What: "reopened", Outcome: "quiet: back before its clearing was said"})
+		case old.told():
 			h.edit(old, "reopened", false)
+		case !needsNothing(old) && !h.queued(old.Key):
+			// Cleared before it was ever said, and back: a problem the operator has not heard of is said.
+			h.deliver(old, "raised")
 		}
 		h.persist(old)
 		return
@@ -553,11 +592,32 @@ func (h *Holder) cleared(key string, quiet bool) {
 			h.Logf("[messenger] %s cleared before it was said: nothing to unsay", key)
 		}
 	default:
-		h.edit(old, "cleared", quiet)
+		// Said once it stays cleared (ClearSettle; a condition that came back, ReopenWindow): a blip of a few
+		// seconds is not said at all (issue 373).
+		h.mu.Lock()
+		old.ClearUnsaid, old.ClearSilent = true, quiet
+		h.mu.Unlock()
 	}
 	h.persist(old)
 }
 
+// clearSettle is how long a record stays cleared before its clearing is said: one that came back before
+// waits the whole reopen window, so a condition that flaps is said cleared once, when it stopped flapping.
+func clearSettle(r *Record) time.Duration {
+	if r.Count > 1 {
+		return ReopenWindow - time.Minute
+	}
+	return ClearSettle
+}
+
+// lastSaid is when a message about a record last went out.
+func lastSaid(r *Record) time.Time {
+	if !r.LastSaid.IsZero() {
+		return r.LastSaid
+	}
+	return r.FirstSent
+}
+
 // Tick does what time asks: reminders, retries, what is held, and forgetting what cleared long
 // enough ago that a new raise is a new message.
 func (h *Holder) Tick() {
@@ -578,7 +638,17 @@ func (h *Holder) Tick() {
 	for _, r := range recs {
 		switch {
 		case !r.Cleared.IsZero():
-			if now.Sub(r.Cleared) >= ReopenWindow {
+			if r.ClearUnsaid && now.Sub(r.Cleared) >= clearSettle(r) {
+				h.mu.Lock()
+				r.ClearUnsaid = false
+				silent := r.ClearSilent
+				h.mu.Unlock()
+				if !r.silenced(now) {
+					h.edit(r, "cleared", silent)
+				}
+				h.persist(r)
+			}
+			if !r.ClearUnsaid && now.Sub(r.Cleared) >= ReopenWindow && !h.queued(r.Key) {
 				h.mu.Lock()
 				delete(h.open, r.Key)
 				h.mu.Unlock()
@@ -601,9 +671,10 @@ func (h *Holder) Tick() {
 			h.deliver(r, "quiet-reminder")
 			h.persist(r)
 		case !r.Reminded && !r.FirstSent.IsZero() && now.Sub(r.Raised) >= remindAfter(r.Severity) &&
-			now.Sub(r.FirstSent) >= remindAfter(r.Severity):
+			now.Sub(lastSaid(r)) >= remindAfter(r.Severity):
 			// Once more after its bound — counted from its raising, and never sooner after it was
-			// first said (an old condition said at a reading of the state is not reminded at once).
+			// last said (an old condition said at a reading of the state is not reminded at once, nor one
+			// just escalated: issue 373).
 			h.mu.Lock()
 			r.Reminded = true
 			h.mu.Unlock()
@@ -714,7 +785,7 @@ func (h *Holder) askLines(rec *AskRecord) []string {
 		}
 	}
 	if !rec.Ask.Expires.IsZero() && rec.Ask.OnExpiry != "" {
-		lines = append(lines, "If nobody answers by "+rec.Ask.Expires.In(h.zone()).Format("15:04")+": "+rec.Ask.OnExpiry+".")
+		lines = append(lines, "If nobody answers by "+by(rec.Ask.Expires, h.Now(), h.zone())+": "+rec.Ask.OnExpiry+".")
 	}
 	return lines
 }

modules/messenger/cmd/messenger/holder_test.go

@@ -17,6 +17,22 @@ type fakeChannel struct {
 	edits    map[string]Message
 	n        int
 	silent   bool // edits notify nobody, as Telegram's
+	// replaced is each message said again in place of an earlier one, as the id it replaced and the message.
+	replaced []replacement
+}
+
+type replacement struct {
+	id string
+	m  Message
+}
+
+// Replace says a message again in place of an earlier one: shown as a new message is, under the same id.
+func (f *fakeChannel) Replace(id string, m Message) error {
+	if f.fail != nil {
+		return f.fail
+	}
+	f.replaced = append(f.replaced, replacement{id, m})
+	return nil
 }
 
 func (f *fakeChannel) SilentEdit() bool { return f.silent }
@@ -208,7 +224,7 @@ func TestTheCapIsALastLineAndIsSaidOnce(t *testing.T) {
 }
 
 func TestAMessageCarryingAnAddressIsRefusedAndSaidWithItsWordsWithheld(t *testing.T) {
-	h, tg, _, _, _ := newHolder(t)
+	h, tg, _, c, _ := newHolder(t)
 	var emitted []string
 	h.Emit = func(e string, _ any) error { emitted = append(emitted, e); return nil }
 	h.Condition(EventRaised, cond("provider.keycloak.ace.failing", Urgent, "cannot reach 192.168.1.20:8443 with token=abc"))
@@ -231,6 +247,8 @@ func TestAMessageCarryingAnAddressIsRefusedAndSaidWithItsWordsWithheld(t *testin
 	}
 	// Its clearing keeps the words withheld.
 	h.Condition(EventCleared, Condition{Key: "provider.keycloak.ace.failing"})
+	c.pass(ClearSettle)
+	h.Tick()
 	for _, m := range tg.edits {
 		if strings.Contains(m.Text(), "192.168") {
 			t.Fatalf("the clearing carried it: %q", m.Text())
@@ -262,24 +280,26 @@ func TestStillOpenPastItsBoundItIsSaidOnceMore(t *testing.T) {
 	settle(h, c)
 	c.pass(59 * time.Minute)
 	h.Tick()
-	if len(tg.sends) != 2 {
-		t.Fatalf("reminded before the hour: %d", len(tg.sends))
+	if len(tg.sends) != 2 || len(tg.replaced) != 0 {
+		t.Fatalf("reminded before the hour: %d %d", len(tg.sends), len(tg.replaced))
 	}
 	c.pass(2 * time.Minute)
 	h.Tick()
-	if len(tg.sends) != 3 || (tg.sends[2].Title != "Still open: bus controller slow-consumer" || !strings.Contains(tg.sends[2].Body, "for 61 min")) {
-		t.Fatalf("urgent reminder: %d %q", len(tg.sends), tg.sends[len(tg.sends)-1].Title)
+	// Said once more in place of its first message (issue 373): one message per problem.
+	if len(tg.sends) != 2 || len(tg.replaced) != 1 || tg.replaced[0].id != "1" ||
+		tg.replaced[0].m.Title != "Still open: bus controller slow-consumer" || !strings.Contains(tg.replaced[0].m.Body, "for 61 min") {
+		t.Fatalf("urgent reminder: %d sends, %+v", len(tg.sends), tg.replaced)
 	}
 	c.pass(3 * time.Hour)
 	h.Tick()
-	if len(tg.sends) != 3 {
+	if len(tg.replaced) != 1 {
 		t.Fatalf("reminded twice")
 	}
 	c.pass(9 * time.Hour) // the warning is now 13 h old
 	h.Tick()
 	settle(h, c)
-	if len(tg.sends) != 4 || tg.sends[3].Title != "Still open: plan 41 stalled" {
-		t.Fatalf("warning reminder: %d", len(tg.sends))
+	if len(tg.sends) != 2 || len(tg.replaced) != 2 || tg.replaced[1].id != "2" || tg.replaced[1].m.Title != "Still open: plan 41 stalled" {
+		t.Fatalf("warning reminder: %d sends, %+v", len(tg.sends), tg.replaced)
 	}
 }
 
@@ -290,6 +310,8 @@ func TestClearedEditsTheFirstMessageAndReopenedWithinTenMinutesIsNotNew(t *testi
 	h.Condition(EventRaised, k)
 	c.pass(14 * time.Minute)
 	h.Condition(EventCleared, Condition{Key: k.Key})
+	c.pass(ClearSettle) // said once it stays cleared (issue 373)
+	h.Tick()
 	if len(tg.sends) != 1 || len(tg.edits) != 1 || len(dt.edits) != 1 {
 		t.Fatalf("telegram sends %d edits %d, desktop edits %d", len(tg.sends), len(tg.edits), len(dt.edits))
 	}
@@ -299,7 +321,7 @@ func TestClearedEditsTheFirstMessageAndReopenedWithinTenMinutesIsNotNew(t *testi
 	if len(h.Open()) != 0 {
 		t.Fatalf("still open")
 	}
-	c.pass(5 * time.Minute)
+	c.pass(3 * time.Minute)
 	k.At = c.now() // a reopening keeps its first raising time; the event says when it happened
 	h.Condition(EventRaised, k)
 	if len(tg.sends) != 1 || !strings.Contains(tg.edits["1"].Title, "(again, 2nd time)") {
@@ -351,8 +373,10 @@ func TestEscalationIsSaidOnce(t *testing.T) {
 	h.Condition(EventChanged, k)
 	h.Condition(EventChanged, k)
 	settle(h, c)
-	if len(dt.sends) != 2 || len(tg.sends) != 1 || !strings.HasPrefix(tg.sends[0].Title, "Now urgent: ") {
-		t.Fatalf("desktop %d telegram %d", len(dt.sends), len(tg.sends))
+	// The desktop's warning is replaced by the urgent message (issue 373); Telegram, which had none, is sent one.
+	if len(dt.sends) != 1 || len(dt.replaced) != 1 || dt.replaced[0].id != "g14=1" ||
+		!strings.HasPrefix(dt.replaced[0].m.Title, "Now urgent: ") || len(tg.sends) != 1 || !strings.HasPrefix(tg.sends[0].Title, "Now urgent: ") {
+		t.Fatalf("desktop %d sends %d replaced, telegram %d", len(dt.sends), len(dt.replaced), len(tg.sends))
 	}
 	// Escalated while the warning still waited its window: one message, the urgent one.
 	k2 := cond("machine.ace.silent", Warning, "the home server is silent")
@@ -360,9 +384,23 @@ func TestEscalationIsSaidOnce(t *testing.T) {
 	k2.Severity = Urgent
 	h.Condition(EventChanged, k2)
 	settle(h, c)
-	if len(dt.sends) != 3 || !strings.HasPrefix(dt.sends[2].Title, "Now urgent: ") {
+	if len(dt.sends) != 2 || !strings.HasPrefix(dt.sends[1].Title, "Now urgent: ") || len(dt.replaced) != 1 {
 		t.Fatalf("desktop %d: %q", len(dt.sends), dt.sends[len(dt.sends)-1].Title)
 	}
+	// Escalated, then the hour of an urgent one passes since it was raised: no reminder until an hour after the
+	// escalation was said (issue 373: "Now urgent" and "Still open" 31 s apart).
+	c.pass(59 * time.Minute)
+	h.Tick()
+	settle(h, c)
+	if len(dt.replaced) != 1 || len(tg.replaced) != 0 {
+		t.Fatalf("reminded within the hour of the escalation: %+v %+v", dt.replaced, tg.replaced)
+	}
+	c.pass(2 * time.Minute)
+	h.Tick()
+	settle(h, c)
+	if len(tg.replaced) != 2 || len(tg.sends) != 2 {
+		t.Fatalf("not reminded an hour after the escalation, in place: telegram %d sends %+v", len(tg.sends), tg.replaced)
+	}
 }
 
 func TestAChannelThatCannotSendSaysSoAndIsTriedAgain(t *testing.T) {
@@ -411,6 +449,12 @@ func TestARestartForgetsNothing(t *testing.T) {
 		t.Fatalf("a restart sent it again")
 	}
 	again.Condition(EventCleared, Condition{Key: k.Key})
+	third := &Holder{Away: tg, Store: st, Now: c.now, Logf: t.Logf}
+	if err := third.Load(); err != nil {
+		t.Fatal(err)
+	}
+	c.pass(ClearSettle)
+	third.Tick() // a clearing not said yet before a restart is said after it
 	if len(tg.edits) != 1 {
 		t.Fatalf("a restart lost the message to edit")
 	}

modules/messenger/cmd/messenger/onemessage_test.go

@@ -0,0 +1,198 @@
+package main
+
+// Issue 373: the operator no longer trusted the mesh's notifications — one problem shown twice, a unit that
+// failed again at each apply said again each time, a question still offered after it ended. One message per
+// problem at any time, updated in place.
+
+import (
+	"strings"
+	"testing"
+	"time"
+)
+
+func saidOn(chs ...*fakeChannel) int {
+	n := 0
+	for _, ch := range chs {
+		n += len(ch.sends) + len(ch.edits) + len(ch.replaced)
+	}
+	return n
+}
+
+// A unit that fails again seconds after each apply clears it: the message continues without a word — no
+// "again, 22nd time", no "Resolved" — and once it stays cleared, its clearing is said once.
+func TestAFlappingConditionIsSaidOnceAndItsClearingOnceWhenItStops(t *testing.T) {
+	h, tg, dt, c, _ := newHolder(t)
+	k := cond("machine.shanks.units", Warning, "2 failed services on shanks")
+	k.Raised = c.now()
+	h.Condition(EventRaised, k)
+	settle(h, c)
+	if len(dt.sends) != 1 || saidOn(tg) != 0 {
+		t.Fatalf("raised: desktop %d, telegram %d", len(dt.sends), saidOn(tg))
+	}
+	for i := 0; i < 22; i++ {
+		c.pass(3 * time.Minute)
+		h.Tick()
+		cl := Condition{Key: k.Key, At: c.now()}
+		h.Condition(EventCleared, cl)
+		c.pass(15 * time.Second)
+		h.Flush()
+		k.At = c.now()
+		h.Condition(EventRaised, k)
+		h.Flush()
+	}
+	runFor(h, c, 20*time.Minute)
+	if got := saidOn(tg, dt); got != 1 {
+		t.Fatalf("a flapping condition was said %d times; want once: desktop %+v %+v %+v", got, dt.sends, dt.edits, dt.replaced)
+	}
+	// Once it has come back, a longer gap — past ClearSettle, inside the reopen window — is still a blip.
+	h.Condition(EventCleared, Condition{Key: k.Key, At: c.now()})
+	runFor(h, c, 5*time.Minute)
+	k.At = c.now()
+	h.Condition(EventRaised, k)
+	runFor(h, c, time.Minute)
+	if got := saidOn(tg, dt); got != 1 {
+		t.Fatalf("a condition that flaps slower was said again: %d", got)
+	}
+	if open := h.Open(); len(open) != 1 || open[0].Count != 24 {
+		t.Fatalf("open: %+v", open)
+	}
+	// A genuinely new problem meanwhile is said.
+	n := cond("machine.ace.disk-full", Urgent, "the home server's disk is full")
+	n.Raised = c.now()
+	h.Condition(EventRaised, n)
+	if len(tg.sends) != 1 || len(dt.sends) != 2 {
+		t.Fatalf("a new problem was swallowed: telegram %d desktop %d", len(tg.sends), len(dt.sends))
+	}
+	// The unit stays mended: its clearing is said once, in place of its message.
+	h.Condition(EventCleared, Condition{Key: k.Key, At: c.now()})
+	runFor(h, c, 30*time.Minute)
+	if len(dt.edits) != 1 || !strings.HasPrefix(dt.edits["g14=1"].Title, "Resolved: ") || len(dt.sends) != 2 {
+		t.Fatalf("its clearing: edits %+v, sends %d", dt.edits, len(dt.sends))
+	}
+}
+
+// A clearing a few seconds long is never said, and the message continues; an urgent problem rang once.
+func TestAnUrgentBlipRingsOnceAndItsBlipsSayNothing(t *testing.T) {
+	h, tg, dt, c, _ := newHolder(t)
+	k := cond("machine.ace.silent", Urgent, "the home server is silent")
+	k.Raised = c.now()
+	h.Condition(EventRaised, k)
+	for i := 0; i < 5; i++ {
+		c.pass(time.Minute)
+		h.Condition(EventCleared, Condition{Key: k.Key, At: c.now()})
+		c.pass(20 * time.Second)
+		h.Tick()
+		k.At = c.now()
+		h.Condition(EventRaised, k)
+	}
+	runFor(h, c, 10*time.Minute)
+	if len(tg.sends) != 1 || len(dt.sends) != 1 || len(tg.edits)+len(dt.edits)+len(tg.replaced)+len(dt.replaced) != 0 {
+		t.Fatalf("telegram %d %d %d, desktop %d %d %d", len(tg.sends), len(tg.edits), len(tg.replaced), len(dt.sends),
+			len(dt.edits), len(dt.replaced))
+	}
+}
+
+// Cleared before it was ever said, and back within the reopen window: a problem the operator never heard of is
+// said, not swallowed as the same message.
+func TestAConditionClearedBeforeItWasSaidAndBackIsSaid(t *testing.T) {
+	h, _, dt, c, _ := newHolder(t)
+	k := cond("machine.shanks.units", Warning, "2 failed services on shanks")
+	k.Raised = c.now()
+	h.Condition(EventRaised, k)
+	c.pass(10 * time.Second)
+	h.Condition(EventCleared, Condition{Key: k.Key, At: c.now()})
+	c.pass(time.Minute)
+	k.At = c.now()
+	h.Condition(EventRaised, k)
+	runFor(h, c, 2*time.Minute)
+	if len(dt.sends) != 1 || !strings.Contains(dt.sends[0].Title, "machine shanks units") {
+		t.Fatalf("desktop %+v", dt.sends)
+	}
+}
+
+// Said first inside a digest, a problem's next message is one of its own, and the word after that replaces or
+// edits that one: never a second message beside it.
+func TestAProblemSaidInADigestGetsAMessageOfItsOwnThatLaterWordsReplace(t *testing.T) {
+	h, tg, _, c, _ := newHolder(t)
+	h.Desk = nil
+	a := cond("seat.s1.silent", Warning, "s1 is silent")
+	b := cond("seat.s2.silent", Warning, "s2 is silent")
+	a.Raised, b.Raised = c.now(), c.now()
+	h.Condition(EventRaised, a)
+	h.Condition(EventRaised, b)
+	settle(h, c)
+	if len(tg.sends) != 1 || !strings.HasPrefix(tg.sends[0].Title, "Mesh: 2 new problems") {
+		t.Fatalf("sends %+v", tg.sends)
+	}
+	b.Severity = Urgent
+	h.Condition(EventChanged, b)
+	settle(h, c)
+	if len(tg.sends) != 2 || !strings.HasPrefix(tg.sends[1].Title, "Now urgent: ") {
+		t.Fatalf("escalation: %+v", tg.sends)
+	}
+	h.Condition(EventCleared, Condition{Key: b.Key, At: c.now()})
+	c.pass(ClearSettle)
+	h.Tick()
+	settle(h, c)
+	if len(tg.sends) != 2 || !strings.HasPrefix(tg.edits["2"].Title, "Resolved: seat s2") {
+		t.Fatalf("its clearing was not an edit of its own message: sends %d, edits %+v", len(tg.sends), tg.edits)
+	}
+}
+
+// An ask's expiry is said with its day when it is not today: an ask lasting a week read as ending tonight.
+func TestAnAsksExpiryIsSaidWithItsDay(t *testing.T) {
+	now := time.Date(2026, 10, 9, 21, 33, 0, 0, time.UTC)
+	for at, want := range map[time.Time]string{
+		now.Add(time.Hour):          "22:33",
+		now.Add(24 * time.Hour):     "tomorrow 21:33",
+		now.Add(7 * 24 * time.Hour): "Fri 16 Oct 21:33",
+	} {
+		if got := by(at, now, time.UTC); got != want {
+			t.Errorf("%s: %q, want %q", at, got, want)
+		}
+	}
+	h, _, _, c, _ := newHolder(t)
+	h.Zone = func() *time.Location { return time.UTC }
+	c.t = now
+	rec := &AskRecord{Asker: ConditionOwner}
+	rec.Ask.Expires = now.Add(7 * 24 * time.Hour)
+	rec.Ask.OnExpiry = "nothing is done"
+	lines := strings.Join(h.askLines(rec), "\n")
+	if !strings.Contains(lines, "If nobody answers by Fri 16 Oct 21:33: nothing is done.") {
+		t.Fatalf("%s", lines)
+	}
+}
+
+// A question on a problem's message, then its reminder: when the question ends, the one message the operator
+// has loses its buttons and says so — none is left offering an answer nobody takes.
+func TestAnEndedQuestionLeavesNoMessageOfferingItsAnswers(t *testing.T) {
+	h, tg, dt, c, store, _ := newRouter(t)
+	link(h, store, c, "42", c.now().Add(-2*time.Hour))
+	k := cond("machine.novox.secret-given", Urgent, "a secret was given at the terminal")
+	k.Raised = c.now()
+	h.Condition(EventRaised, k)
+	settle(h, c)
+	a := ackAsk(c, "q-1")
+	a.About = k.Key
+	a.Expires = c.now().Add(3 * time.Hour)
+	submit(t, h, ConditionOwner, a)
+	settle(h, c)
+	for i := 0; i < 4*60; i++ {
+		c.pass(time.Minute)
+		stand(h, c)
+		h.Tick()
+		h.Flush()
+	}
+	if rec := store.asks[ConditionOwner+".q-1"]; rec.State == StateOpen {
+		t.Fatalf("the ask did not expire: %+v", rec.State)
+	}
+	for _, ch := range []*fakeChannel{tg, dt} {
+		if len(ch.sends) != 1 {
+			t.Fatalf("%s: %d messages for one problem", ch.name, len(ch.sends))
+		}
+		last := ch.edits[map[string]string{"telegram": "1", "desktop": "g14=1"}[ch.name]]
+		if len(ch.replaced) == 0 || len(last.Actions) > 1 || !strings.Contains(last.Body, "No longer answerable") {
+			t.Fatalf("%s: replaced %d, the message now: %q %v", ch.name, len(ch.replaced), last.Text(), labelsOf(last))
+		}
+	}
+}

modules/messenger/cmd/messenger/outbox.go

@@ -294,7 +294,9 @@ func (h *Holder) flushChannel(ch Channel, now time.Time, force bool) {
 		// an ask whose approval was not offered folded into a digest, and its one answer lost with it).
 		var alone, rest []entry
 		for _, e := range entries {
-			if len(e.msg.Actions) > 1 || (len(e.msg.Actions) > 0 && e.r != nil && e.r.Ask != "") {
+			// A message said again about a record shown here goes alone too: it replaces that record's message,
+			// so a reminder is never a digest line beside the message it follows (issue 373).
+			if len(e.msg.Actions) > 1 || (len(e.msg.Actions) > 0 && e.r != nil && e.r.Ask != "") || h.replacing(ch, e) != "" {
 				alone = append(alone, e)
 			} else {
 				rest = append(rest, e)
@@ -329,12 +331,26 @@ type entry struct {
 	msg Message
 }
 
-// sendEntries sends entries as one message — itself when alone, a digest when several — and records it.
+// replacing is the id of the message an entry replaces on a channel: the record's own message there, when the
+// entry says it again (not its clearing) and the channel can replace; "" for a new message.
+func (h *Holder) replacing(ch Channel, e entry) string {
+	if e.r == nil || e.it.What == "cleared" || !replaces(ch) {
+		return ""
+	}
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	return e.r.Sent[ch.Name()]
+}
+
+// sendEntries sends entries as one message — itself when alone, a digest when several — and records it. A
+// record said again where its message is shown replaces that message (issue 373): one message per problem.
 func (h *Holder) sendEntries(ch Channel, entries []entry, now time.Time) bool {
 	name := ch.Name()
 	var m Message
+	prior := ""
 	if len(entries) == 1 {
 		m = entries[0].msg
+		prior = h.replacing(ch, entries[0])
 	} else {
 		items := make([]item, len(entries))
 		msgs := make([]Message, len(entries))
@@ -343,7 +359,13 @@ func (h *Holder) sendEntries(ch Channel, entries []entry, now time.Time) bool {
 		}
 		m = digest(items, msgs)
 	}
-	id, err := ch.Send(m)
+	var id string
+	var err error
+	if prior != "" {
+		id, err = prior, ch.(replacer).Replace(prior, m)
+	} else {
+		id, err = ch.Send(m)
+	}
 	h.noteChannel(name, err)
 	if err != nil {
 		return false
@@ -367,22 +389,25 @@ func (h *Holder) sendEntries(ch Channel, entries []entry, now time.Time) bool {
 			if r.Sent == nil {
 				r.Sent = map[string]string{}
 			}
-			if _, has := r.Sent[name]; !has {
-				own := ""
-				if len(entries) == 1 {
-					own = id
-				}
-				r.Sent[name] = own
+			if len(entries) == 1 {
+				// Its own message: the one later words replace or edit — also after it was said in a digest.
+				r.Sent[name] = id
+			} else if _, has := r.Sent[name]; !has {
+				r.Sent[name] = ""
 			}
 			if r.FirstSent.IsZero() {
 				r.FirstSent = now
 			}
+			r.LastSaid = now
 		}
 	}
 	h.mu.Unlock()
 	key, what := "(digest)", fmt.Sprintf("digest of %d", len(entries))
 	if len(entries) == 1 {
 		key, what = entries[0].it.Key, entries[0].it.What
+		if prior != "" {
+			what += ", in place of its earlier message"
+		}
 	}
 	h.record(Sent{At: now, Channel: name, Key: key, What: what, Outcome: "sent"})
 	for _, e := range entries {

modules/messenger/cmd/messenger/seatchannel.go

@@ -243,6 +243,15 @@ func (c *SeatChannel) Send(m Message) (string, error) {
 	return handle, c.put(handle, m, false)
 }
 
+// Replace says a message again under the handle of one shown before: the channel takes the earlier one away
+// and shows this one as a new message is shown — ringing as its kind rings (issue 373). An edit is quiet.
+func (c *SeatChannel) Replace(handle string, m Message) error {
+	if handle == "" {
+		return errors.New("no message on record to replace")
+	}
+	return c.put(handle, m, false)
+}
+
 // Edit replaces the message a handle names.
 func (c *SeatChannel) Edit(handle string, m Message) error {
 	if handle == "" {
@@ -311,6 +320,13 @@ func (c *KindChannel) Send(m Message) (string, error) {
 	handle := newHandle()
 	return handle, s.putOn(c.Kind, handle, m, false)
 }
+func (c *KindChannel) Replace(handle string, m Message) error {
+	if handle == "" {
+		return errors.New("no message on record to replace")
+	}
+	s := &SeatChannel{Bench: c.Bench, Publish: c.Publish}
+	return s.putOn(c.Kind, handle, m, false)
+}
 func (c *KindChannel) Edit(handle string, m Message) error {
 	s := &SeatChannel{Bench: c.Bench, Publish: c.Publish}
 	return s.putOn(c.Kind, handle, m, true)

modules/messenger/cmd/messenger/sync.go

@@ -68,6 +68,7 @@ func (h *Holder) Sync(open []Condition, asked time.Time) SyncResult {
 			if !old.Cleared.IsZero() {
 				// Ended here, open there: back to open, quietly — the reading is not an event.
 				old.Cleared = time.Time{}
+				old.ClearUnsaid, old.ClearSilent = false, false
 				old.Count++
 			}
 			old.Summary, old.Subject, old.Kind, old.SilencedTill = rec.Summary, rec.Subject, rec.Kind, rec.SilencedTill

modules/messenger/cmd/messenger/words.go

@@ -198,6 +198,23 @@ func when(t, now time.Time, loc *time.Location) string {
 	return lt.Format("2 Jan 15:04")
 }
 
+// by is a moment ahead as the operator reads it, in their zone: "23:33" today, "tomorrow 23:33", "Fri 16 Oct
+// 23:33" later. An ask's expiry was said as a clock time alone, so an ask lasting a week read as one ending
+// tonight (issue 373).
+func by(t, now time.Time, loc *time.Location) string {
+	lt, ln := t.In(loc), now.In(loc)
+	y1, m1, d1 := lt.Date()
+	y2, m2, d2 := ln.Date()
+	if y1 == y2 && m1 == m2 && d1 == d2 {
+		return lt.Format("15:04")
+	}
+	ty, tm, td := ln.AddDate(0, 0, 1).Date()
+	if y1 == ty && m1 == tm && d1 == td {
+		return "tomorrow " + lt.Format("15:04")
+	}
+	return lt.Format("Mon 2 Jan 15:04")
+}
+
 func capital(s string) string {
 	if s == "" {
 		return s

modules/messenger/cmd/messenger/words_test.go

@@ -225,6 +225,8 @@ func TestRealNotificationsReadInOneGlanceAndAreAnsweredFromTheNotification(t *te
 				t.Fatal(err)
 			}
 			h.Condition(EventCleared, cleared)
+			c.pass(ClearSettle)
+			h.Tick()
 			end := dt.edits["g14=1"]
 			if end.Title != e.cleared || end.Body != "" || len(end.Actions) != 0 {
 				t.Errorf("clearance %q / %q / %v, want one line %q", end.Title, end.Body, end.Actions, e.cleared)

modules/telegram/README.md

@@ -8,6 +8,9 @@ as the operator.
 - **Shows what the router sends** (its kind's worker on the `channel` queue): a message, a question with
   buttons — each button carries only the router's one-time ticket — or an edit of a message shown before.
   It sends to the account the router names as linked, or, before one is, to the chat a `/start` came from.
+  A message sent under a handle already shown (a reminder, an escalation) **replaces** it (issue 373): the
+  earlier message is deleted and the new one sent, ringing as its kind rings, since an edit here notifies
+  nobody; one the service will not delete loses its buttons and says a newer message follows.
 - **Says what the operator chose** on `intake` under its own kind: a tapped button (`choice`), with the
   sender as Telegram authenticated it; `/start` (`link`); a message it could not deliver (`failed`); and
   whether it can send (`standing`). Only a private chat with the account itself counts.

modules/telegram/cmd/telegram/channel.go

@@ -10,7 +10,8 @@ package main
 //     handle). Up to 4096 characters arrive whole; longer is cut and the cut said (D1). A warning or a
 //     clearing arrives without sound, an urgent message or a question rings (D4). A rate limit is waited out
 //     as told (D5); a refusal is a permanent failure, said to the router, never retried; an edit to the same
-//     text is a success (D6). A message that cannot be delivered after three tries is said as failed.
+//     text is a success (D6). A message that cannot be delivered after three tries is said as failed. A
+//     `send` or `show` under a handle already shown replaces that message: deleted, and the new one sent.
 //   - **What arrives** is long-polled: outbound only. A tapped button is said as a `choice` with the sender
 //     the service authenticated, and acknowledged on the phone with the router's word on it — what was
 //     recorded, or why it was not — which comes as a reply to the tap; without one in TapWait, with words that
@@ -232,11 +233,19 @@ func (c *Channel) Take(subject string, body json.RawMessage) error {
 	words, buttons := text(m), c.buttons(m)
 	silent := m.Silent || (!m.Urgent && len(buttons) == 0)
 	var place *Placed
-	if verb == asks.Edit {
+	if verb == asks.Edit || !m.Secret {
 		if place, err = c.Store.Placed(m.Handle); err != nil {
 			return err // the state is away: offered again
 		}
 	}
+	if verb != asks.Edit && place != nil {
+		// **A message said again under a handle already shown replaces it** (issue 373): a reminder or an
+		// escalation is one message per problem, not one more beside it. An edit here notifies nobody, so the
+		// earlier message is deleted and this one sent, ringing as its kind rings; one the service will not
+		// delete loses its buttons and says where the newer one is.
+		c.replaced(*place)
+		place = nil
+	}
 	for try := 1; ; try++ {
 		var id int64
 		switch {
@@ -274,6 +283,19 @@ func (c *Channel) Take(subject string, body json.RawMessage) error {
 	}
 }
 
+// replaced takes an earlier message out of the chat: deleted, or where the service refuses that (a message
+// older than two days), its buttons taken away and the newer message named.
+func (c *Channel) replaced(p Placed) {
+	err := c.Bot.Delete(p.Chat, p.ID)
+	if err == nil {
+		return
+	}
+	c.Logf("[telegram] an earlier message could not be deleted (%v); its buttons are taken away instead", err)
+	if err := c.Bot.Edit(p.Chat, p.ID, "Replaced by a newer message below.", nil); err != nil && !gone(err) {
+		c.Logf("[telegram] an earlier message could not be marked replaced either: %v", err)
+	}
+}
+
 func (c *Channel) newMessage(handle string, chat int64, words string, buttons [][2]string, silent bool, id *int64) error {
 	got, err := c.Bot.Send(chat, words, buttons, silent)
 	if err != nil {

modules/telegram/cmd/telegram/channel_test.go

@@ -580,3 +580,48 @@ func TestAToastIsCutAtTelegramsBound(t *testing.T) {
 		t.Errorf("toast %q", got)
 	}
 }
+
+// Issue 373: a reminder or an escalation is sent under the handle of the message it follows, and replaces it:
+// the earlier one leaves the chat and the new one rings as its kind rings. One the service will not delete
+// loses its buttons. A new handle is a new message, and nothing is deleted.
+func TestAMessageSaidAgainUnderItsHandleReplacesTheEarlierOne(t *testing.T) {
+	c, f, _, st := newChannel(t, goodToken)
+	subject, body := work(asks.Show, asks.Message{Handle: "m1", Title: "Urgent: ace silent", Urgent: true, To: "42",
+		Buttons: []asks.Button{{Label: "Silence for a week", Ticket: "0123456789abcdef0123456789abcdef"}}})
+	if err := c.Take(subject, body); err != nil {
+		t.Fatal(err)
+	}
+	first := st.placed["m1"].ID
+	subject, body = work(asks.Send, asks.Message{Handle: "m2", Title: "another problem", To: "42"})
+	_ = c.Take(subject, body)
+	if len(f.of("deleteMessage")) != 0 {
+		t.Fatal("a new handle deleted a message")
+	}
+	subject, body = work(asks.Show, asks.Message{Handle: "m1", Title: "Still open: ace silent", Urgent: true, To: "42",
+		Buttons: []asks.Button{{Label: "Silence for a week", Ticket: "fedcba9876543210fedcba9876543210"}}})
+	if err := c.Take(subject, body); err != nil {
+		t.Fatal(err)
+	}
+	del := f.of("deleteMessage")
+	if len(del) != 1 || del[0].Body["message_id"] != float64(first) {
+		t.Fatalf("the earlier message was not deleted: %+v", del)
+	}
+	sent := f.of("sendMessage")
+	if len(sent) != 3 || sent[2].Body["disable_notification"] != false || st.placed["m1"].ID == first {
+		t.Fatalf("the reminder was not sent ringing in its place: %d sends, placed %d", len(sent), st.placed["m1"].ID)
+	}
+	// The service refuses the delete: the earlier message loses its buttons instead.
+	f.answer["deleteMessage"] = func(map[string]any) (int, string) {
+		return 400, `{"ok":false,"error_code":400,"description":"Bad Request: message can't be deleted"}`
+	}
+	second := st.placed["m1"].ID
+	subject, body = work(asks.Send, asks.Message{Handle: "m1", Title: "Now urgent: ace silent", Urgent: true, To: "42"})
+	_ = c.Take(subject, body)
+	ed := f.of("editMessageText")
+	if len(ed) != 1 || ed[0].Body["message_id"] != float64(second) || !strings.Contains(ed[0].Body["text"].(string), "Replaced") {
+		t.Fatalf("an undeletable earlier message kept its buttons: %+v", ed)
+	}
+	if kb, _ := json.Marshal(ed[0].Body["reply_markup"]); string(kb) != `{"inline_keyboard":[]}` {
+		t.Errorf("its buttons stayed: %s", kb)
+	}
+}