a named time that did not parse never borrows the last one (V-543)

Four reminders in a row on the box all landed at the first one's hour, each
confirmed as if it had been read from the sentence: "напомни без четверти
восемь выходить" fired at 07:30. followUpMerge inherits a missing slot from
the previous same-intent turn, and a reminder time is one of those slots. It
also filled the slot before actionReminder's own fallback parse could run, so
inheriting hid a time that did parse.

router.MentionsTime tells the two cases apart. A sentence that names no time
still inherits, which is the follow-up the seam exists for. A sentence that
names one the parser missed keeps an empty slot, so she asks. Missing the hour
he said costs a question; borrowing one costs an alarm he stops thinking about.

Signals are lexicon classes and digits only: the day qualifiers, parts of day,
day offsets, weekdays by lemma through morph, the half-past and quarter-to
markers, and a written clock whose minutes are two digits so a score does not
pass for one.

Fact keys and act fns inherit through the same call and are left alone: a
borrowed key answers about the wrong thing out loud, which he hears, while a
borrowed hour is silent until it fires.

cmd/mavend/followup.go

@@ -97,7 +97,8 @@ var anaphoraResolver router.AnaphoraResolver
 // followUpMerge fills the current turn's missing slots from a prior
 // non-expired session — the multi-turn seam. It handles three cases:
 //
-//  1. Same-intent: inherit missing slots via InheritSlots (existing behavior).
+//  1. Same-intent: inherit missing slots via InheritSlots (existing behavior),
+//     except a reminder time the current sentence named and the parser missed.
 //  2. Cross-intent anaphora: if the current utterance contains a pronoun
 //     ("это" / "он" / "она" etc.) AND the prior session has a key, inherit
 //     the key for fact-lookup queries and reminder creation.
@@ -113,8 +114,22 @@ func followUpMerge(prev *dialogue.Session, dec router.Decision, now time.Time) r
 
 	// Case 1: same-intent inheritance (existing).
 	if prev.Intent == dialogue.Intent(dec.Intent) {
+		// A reminder that named an hour nobody could read must not borrow the
+		// last one's. Two reminders in a row and the second landed at the
+		// first's time, confirmed as if it had been read from the sentence:
+		// "напомни без четверти восемь выходить" fired at 07:30 (V-543). The
+		// hour is also what fills before the action's own fallback parse can
+		// run, so inheriting it hid a time that did parse.
+		//
+		// Inheriting is still right when the sentence names no time at all,
+		// which is the follow-up this seam exists for.
+		blockTime := dec.Intent == router.IntentReminder &&
+			!dec.Slots.HasTime && router.MentionsTime(dec.Utterance)
 		merged := dialogue.InheritSlots(prev.Slots, toDialogueSlots(dec.Slots))
 		dec.Slots = applyDialogueSlots(dec.Slots, merged)
+		if blockTime {
+			dec.Slots.Time, dec.Slots.HasTime = time.Time{}, false
+		}
 		return dec
 	}
 

cmd/mavend/followup_test.go

@@ -35,6 +35,42 @@ func TestFollowUpMerge(t *testing.T) {
 		}
 	})
 
+	// V-543, measured on the box: four reminders in a row all landed at the
+	// first one's hour, each confirmed as if it had been read from the sentence.
+	// A sentence that names a time and fails to parse must ask, not borrow.
+	t.Run("a named time that did not parse is not inherited", func(t *testing.T) {
+		for _, utt := range []string{
+			"напомни без четверти восемь выходить",
+			"напомни в половине первого пообедать",
+			"напомни завтра принять лекарство",
+			"remind me at noon to stretch",
+		} {
+			cur := router.Decision{
+				Intent:    router.IntentReminder,
+				Utterance: utt,
+				Slots:     router.Slots{Text: utt},
+			}
+			got := followUpMerge(prev, cur, base.Add(30*time.Second))
+			if got.Slots.HasTime {
+				t.Errorf("%q borrowed the previous hour %v", utt, got.Slots.Time)
+			}
+		}
+	})
+
+	// The follow-up this seam exists for still works: the sentence names no
+	// time, so the previous one is the only one it could mean.
+	t.Run("a follow-up naming no time still inherits", func(t *testing.T) {
+		cur := router.Decision{
+			Intent:    router.IntentReminder,
+			Utterance: "и ещё полить цветы",
+			Slots:     router.Slots{Text: "полить цветы"},
+		}
+		got := followUpMerge(prev, cur, base.Add(30*time.Second))
+		if !got.Slots.HasTime || !got.Slots.Time.Equal(fireAt) {
+			t.Errorf("time not inherited: HasTime=%v Time=%v", got.Slots.HasTime, got.Slots.Time)
+		}
+	})
+
 	t.Run("current slot wins over prior (gaps only)", func(t *testing.T) {
 		own := base.Add(48 * time.Hour)
 		cur := router.Decision{