a time slot naming no hour is asked about, never filled (V-579)

Both parsers answer a bare day word with that day at the current minute, so "на
завтра" set a reminder at 01:38, the minute he happened to be speaking. The gate
is textual now: NamesAnHour reads the sentence, and the slot stays empty when
nobody said an hour.

Beside it, NamesAnInterval and HourIsAmbiguous, which the owner's commit rule
reads. "на" joins "в" as a frame around a spoken hour in both parsers, a clock
keeps its meaning with a full stop after it, and the stub applies a day word and
a part-of-day qualifier from anywhere in the sentence rather than only from the
token after the hour.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

internal/router/slots.go

@@ -55,7 +55,11 @@ func (e Extractor) Extract(ctx context.Context, intent Intent, utterance string,
 	switch intent {
 	case IntentReminder:
 		if e.Time != nil {
-			if t, ok, err := e.Time.Parse(ctx, utterance, now); err == nil && ok {
+			// NamesAnHour is the gate, not the parser's ok (V-577, V-579). A
+			// sentence that names a day and no hour parses to that day at the
+			// current minute, and filling the slot with it invents the answer
+			// she asked for. Left empty, the daemon asks.
+			if t, ok, err := e.Time.Parse(ctx, utterance, now); err == nil && ok && NamesAnHour(utterance) {
 				s.Time = t
 				s.HasTime = true
 			}
@@ -171,6 +175,11 @@ func afterWord(s, w string) string {
 	return ""
 }
 
+// hourPrepositions — the words a spoken hour sits behind. Three, and no more:
+// the lexicon's frame set is much wider, and a word goes in here only when the
+// number after it is an hour of the day rather than a count of anything.
+var hourPrepositions = map[string]bool{"в": true, "во": true, "на": true}
+
 // StubDateTimeParser — a tiny relative/absolute parser standing in for
 // `dateparser` until the i18n module lands. Handles "in Nh"/"in Nm"/"in Ns" and
 // "at HH:MM" / "HH:MM". The production path replaces this wholesale; the
@@ -210,18 +219,27 @@ func (StubDateTimeParser) Parse(_ context.Context, text string, now time.Time) (
 	// after the hour moves it into the afternoon: "в 7 вечера" is 19:00, and
 	// with SpellOutDigits in front of this that is what "в семь вечера" reads
 	// as too (Vikunja #469).
+	//
+	// "на" and "во" frame a spoken hour the same way, and until V-579 only "в"
+	// did: "в 9" set the reminder and "на 9" was not read at all.
 	for i := 0; i+1 < len(toks); i++ {
-		if toks[i] != "в" {
+		if !hourPrepositions[toks[i]] {
 			continue
 		}
 		t, ok := parseClock(toks[i+1], now)
 		if !ok {
 			continue
 		}
-		if i+2 < len(toks) {
-			t = applyRuQualifier(t, toks[i+2], now)
+		// The qualifier is looked for anywhere in the sentence, not only right
+		// after the hour. It arrives on its own turn when she asks which half of
+		// the day he meant, and "на 9" plus "вечера" is one time (V-579).
+		if qual := ruQualifierIn(toks); qual != "" {
+			t = applyRuQualifier(t, qual, now)
 		}
-		return t, true, nil
+		// A day word anywhere in the sentence moves the hour onto that day. This
+		// scan runs before the calendar one below, so without this "напомни
+		// завтра в 15:00" landed today and V-579 asks about exactly that gap.
+		return applyRuDayShift(t, toks, now), true, nil
 	}
 
 	// "через <N> <unit>" / "через <unit>" (bare = 1) / "через полчаса".
@@ -307,6 +325,10 @@ func sortDescByLen(ss []string) {
 // parseClock — "7", "7:30" → today at that time; if already past today, roll
 // to tomorrow (a "wake me 7" at 8pm fires tomorrow 7). Used by the stub scan.
 func parseClock(clock string, now time.Time) (time.Time, bool) {
+	// Speech arrives with its punctuation attached: "на 9." ends a sentence and
+	// still names nine o'clock (V-579). The colon is kept, since it is the one
+	// mark that is part of a clock.
+	clock = strings.Trim(clock, ".,!?;")
 	parts := strings.SplitN(clock, ":", 2)
 	h, err := strconv.Atoi(parts[0])
 	if err != nil || h < 0 || h > 23 {
@@ -480,6 +502,39 @@ func midnight(now time.Time, days int) time.Time {
 //
 // The date is recomputed rather than shifted, so an hour that parseClock
 // already pushed to tomorrow does not land two days out.
+// applyRuDayShift moves an hour onto the day the sentence names, if it names
+// one. The hour is kept exactly as read: the day word says which day and says
+// nothing about when in it.
+// ruQualifierIn returns the first part-of-day word in the sentence, or "".
+func ruQualifierIn(toks []string) string {
+	for _, tok := range toks {
+		switch cleanWord(tok) {
+		case "утра", "вечера", "дня", "ночи":
+			return cleanWord(tok)
+		}
+	}
+	return ""
+}
+
+func applyRuDayShift(t time.Time, toks []string, now time.Time) time.Time {
+	for _, tok := range toks {
+		days := 0
+		switch cleanWord(tok) {
+		case "сегодня":
+			days = 0
+		case "завтра":
+			days = 1
+		case "послезавтра":
+			days = 2
+		default:
+			continue
+		}
+		base := now.AddDate(0, 0, days)
+		return time.Date(base.Year(), base.Month(), base.Day(), t.Hour(), t.Minute(), 0, 0, now.Location())
+	}
+	return t
+}
+
 func applyRuQualifier(t time.Time, qualifier string, now time.Time) time.Time {
 	h := t.Hour()
 	switch strings.Trim(strings.ToLower(qualifier), ".,!?;:") {