Answer the day the user asked about and the city he named (#388)

replySystem had two arms that PR 30 made reachable, and both answered confidently wrong: the date arm keyword-matched "числ" and always answered today, so "какое число завтра" answered today; the clock arm ignored a named city and answered local time. The date arm now reads the day word through router.ParseCalendarDate (which grew послезавтра/вчера and now cuts the day boundary in the local zone instead of UTC). The clock arm answers the named zone when it resolves offline from the tz database embedded in the binary, and otherwise says plainly that she only knows local time.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CGeSZxh1DCtRxmFVSYVGvJ

internal/router/slots.go

@@ -449,16 +449,30 @@ func (AnaphoraResolver) Resolve(text string) (ref string, ok bool) {
 	return "", false
 }
 
-// ParseCalendarDate detects RU calendar date words in text and returns the
-// resolved time (midnight UTC+0 for "сегодня"/"today", next day for "завтра"/"tomorrow").
-// Returns zero time + false if no match.
+// ParseCalendarDate detects RU/EN calendar day words in text and returns
+// midnight of that day in now's own time zone. Handles "сегодня", "завтра",
+// "послезавтра", "вчера" (and the English words). Returns zero time + false
+// if no match.
+//
+// "послезавтра" is checked before "завтра" because it contains it.
 func ParseCalendarDate(text string, now time.Time) (time.Time, bool) {
 	lower := strings.ToLower(text)
-	if strings.Contains(lower, "сегодня") || strings.Contains(lower, "today") {
-		return now.Truncate(24 * time.Hour), true
-	}
-	if strings.Contains(lower, "завтра") || strings.Contains(lower, "tomorrow") {
-		return now.Truncate(24 * time.Hour).Add(24 * time.Hour), true
+	switch {
+	case strings.Contains(lower, "сегодня") || strings.Contains(lower, "today"):
+		return midnight(now, 0), true
+	case strings.Contains(lower, "послезавтра") || strings.Contains(lower, "day after tomorrow"):
+		return midnight(now, 2), true
+	case strings.Contains(lower, "завтра") || strings.Contains(lower, "tomorrow"):
+		return midnight(now, 1), true
+	case strings.Contains(lower, "вчера") || strings.Contains(lower, "yesterday"):
+		return midnight(now, -1), true
 	}
 	return time.Time{}, false
 }
+
+// midnight returns the start of the day that is `days` away from now, in
+// now's time zone (now.Truncate(24h) would cut on a UTC boundary instead).
+func midnight(now time.Time, days int) time.Time {
+	y, m, d := now.AddDate(0, 0, days).Date()
+	return time.Date(y, m, d, 0, 0, 0, 0, now.Location())
+}

internal/router/slots_ru_test.go

@@ -45,6 +45,9 @@ func TestParseCalendarDate(t *testing.T) {
 		{"расписание на завтра", time.Date(2026, 7, 7, 0, 0, 0, 0, time.UTC), true},
 		{"what's today", time.Date(2026, 7, 6, 0, 0, 0, 0, time.UTC), true},
 		{"tomorrow plans", time.Date(2026, 7, 7, 0, 0, 0, 0, time.UTC), true},
+		{"какое число послезавтра", time.Date(2026, 7, 8, 0, 0, 0, 0, time.UTC), true},
+		{"что было вчера", time.Date(2026, 7, 5, 0, 0, 0, 0, time.UTC), true},
+		{"yesterday plans", time.Date(2026, 7, 5, 0, 0, 0, 0, time.UTC), true},
 		{"какая погода", time.Time{}, false},
 		{"сколько времени", time.Time{}, false},
 		{"", time.Time{}, false},