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/router/slots.go

@@ -175,10 +175,14 @@ func afterWord(s, w string) string {
 	return ""
 }
 
-// hourPrepositions — the words a spoken hour sits behind. Three, and no more:
+// hourPrepositions — the words a spoken hour sits behind. Five, 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}
+//
+// "к" and "ко" joined the three on V-609. "напомни к двум часам" named an hour
+// and parsed to nothing, so the reminder reached the daemon with no time and she
+// asked the open question about an hour he had just said.
+var hourPrepositions = map[string]bool{"в": true, "во": true, "на": true, "к": true, "ко": true}
 
 // StubDateTimeParser — a tiny relative/absolute parser standing in for
 // `dateparser` until the i18n module lands. Handles "in Nh"/"in Nm"/"in Ns" and
@@ -398,10 +402,18 @@ func leadingWordNumber(s string) (int, string, bool) {
 }
 
 func unitToDuration(n int, unit string) (time.Duration, bool) {
-	switch unit {
-	case "h", "hour", "hours", "hr", "hrs":
+	// The hour and the minute nouns are closed classes with one home in the
+	// lexicon, and the list here used to be short of the oblique forms (V-609).
+	if lexicon.IsHourUnit(unit) {
 		return time.Duration(n) * time.Hour, true
-	case "m", "min", "mins", "minute", "minutes":
+	}
+	if lexicon.IsMinuteUnit(unit) {
+		return time.Duration(n) * time.Minute, true
+	}
+	switch unit {
+	case "h", "hr", "hrs":
+		return time.Duration(n) * time.Hour, true
+	case "m", "min", "mins":
 		return time.Duration(n) * time.Minute, true
 	case "s", "sec", "secs", "second", "seconds":
 		return time.Duration(n) * time.Second, true
@@ -409,10 +421,6 @@ func unitToDuration(n int, unit string) (time.Duration, bool) {
 	case "day", "days":
 		return time.Duration(n) * 24 * time.Hour, true
 	// Russian units (inflected forms)
-	case "час", "часа", "часов":
-		return time.Duration(n) * time.Hour, true
-	case "минута", "минуты", "минут":
-		return time.Duration(n) * time.Minute, true
 	case "день", "дня", "дней":
 		return time.Duration(n) * 24 * time.Hour, true
 	case "неделя", "недели", "недель":