The hour unit has one home and it carries the dative plural (V-609)

"напомни к двум часам позвонить маме" now reads two o'clock. It read no
time at all, so the reminder reached the daemon with an empty slot and she
asked the open "Когда?" about an hour he had just said.

The word that lost it was "часам", the dative plural of "час". Four sets in
internal/router listed the hour noun and every one of them stopped at
"часу". They are now one lexicon key, hour_units, read by all four through
lexicon.HourUnits and lexicon.IsHourUnit. The minute noun had the same gap
one word over and gets the same treatment in minute_units: "минутам" was
missing everywhere "минут" and "минуты" were present. The slot_value_frame
set no longer lists either noun and appends both, so there is one copy of
each closed class rather than a copy per caller.

Two more sites had to move for the sentence to parse. hourPrepositions knew
"в", "во" and "на" and not "к", and the python dateparser rewrite knew the
same three. Both now read the fifth preposition and the oblique forms of the
hour that follow it.

Fixture unchanged: classifier+hash 27/91 before and after, reach 18/30
before and after, no case moved in either direction.

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

internal/lexicon/lexicon.go

@@ -65,7 +65,7 @@ func mustLoad() lexiconFile {
 		"day_offsets", "weekdays", "weekdays_english", "months_genitive", "hours_spoken",
 		"not_place_after_v", "parts_of_day", "reminder_verbs", "half_hour",
 		"filler_particles", "task_done_words", "task_drop_words",
-		"confirm_yes", "confirm_no",
+		"confirm_yes", "confirm_no", "hour_units", "minute_units",
 	} {
 		s, ok := f.Sets[name]
 		if !ok || (len(s.Words) == 0 && len(s.Values) == 0) {
@@ -139,7 +139,40 @@ func TaskDropWords() []string { return words("task_drop_words") }
 // making the utterance a request of its own. A caller strips these (along with
 // the numbers and the other closed time sets) to see whether an utterance
 // carries any content beside the value it was asked for. See the set's note.
-func SlotValueFrame() []string { return words("slot_value_frame") }
+// The hour and the minute nouns are part of the frame and are kept in their own
+// sets, so there is one copy of each closed class rather than a copy per caller.
+func SlotValueFrame() []string {
+	out := words("slot_value_frame")
+	out = append(out, HourUnits()...)
+	out = append(out, MinuteUnits()...)
+	return out
+}
+
+// HourUnits returns every form of the hour noun, and MinuteUnits every form of
+// the minute noun. One home for each, because four router sets used to list the
+// hour and all four stopped at "часу" (V-609). A caller folding time words into
+// one set reads these; a caller asking about a single word reads IsHourUnit or
+// IsMinuteUnit.
+func HourUnits() []string { return words("hour_units") }
+
+// MinuteUnits — see HourUnits.
+func MinuteUnits() []string { return words("minute_units") }
+
+// IsHourUnit reports whether a word is the hour noun in any form.
+func IsHourUnit(word string) bool { return inSet("hour_units", word) }
+
+// IsMinuteUnit reports whether a word is the minute noun in any form.
+func IsMinuteUnit(word string) bool { return inSet("minute_units", word) }
+
+func inSet(set, word string) bool {
+	w := norm(word)
+	for _, s := range ru.Sets[set].Words {
+		if w == s {
+			return true
+		}
+	}
+	return false
+}
 
 // DialogueCancel returns the ways he calls off the request Maven is assembling.
 // Distinct from TaskDropWords, which abandons an item that already exists.