fix(calendar): BYDAY=1MO — RecurrenceRule хранит/сериализует ординал (был потерян в toRrule) + разворот n-го дня месяца в CalendarRecurrence +4 теста (P1 добивка, mail/101)

feature/calendar/src/main/java/ru/forbion/f7cloud/feature/calendar/CalendarRecurrence.kt

@@ -83,13 +83,58 @@ object CalendarRecurrence {
         upTo: LocalDate,
         onOccurrence: (LocalDate) -> Boolean,
     ) {
-        if (rule.freq == "WEEKLY" && rule.byDays.isNotEmpty()) {
+        when {
+            rule.freq == "MONTHLY" && rule.monthlyOrdinal != null && rule.byDays.isNotEmpty() ->
+                forEachMonthlyNthWeekday(rule, start, upTo, onOccurrence)
+            rule.freq == "WEEKLY" && rule.byDays.isNotEmpty() ->
                 forEachWeeklyByDay(rule, start, upTo, onOccurrence)
-        } else {
+            else -> forEachSimpleStep(rule, start, upTo, onOccurrence)
-            forEachSimpleStep(rule, start, upTo, onOccurrence)
         }
     }
 
+    /** MONTHLY с BYDAY=<n><день>: n-й (или последний при -1) день недели каждого интервал-месяца. */
+    private inline fun forEachMonthlyNthWeekday(
+        rule: RecurrenceRule,
+        start: LocalDate,
+        upTo: LocalDate,
+        onOccurrence: (LocalDate) -> Boolean,
+    ) {
+        val interval = rule.interval.coerceAtLeast(1)
+        val (until, maxCount) = bounds(rule)
+        val ordinal = rule.monthlyOrdinal ?: return
+        val dow = RecurrenceRule.ICS_DAYS.firstOrNull { it in rule.byDays }?.let { icsDayToDow(it) } ?: return
+        val baseMonth = java.time.YearMonth.from(start)
+        var emitted = 0
+        var n = 0L
+        while (n < MAX_STEPS) {
+            val month = baseMonth.plusMonths(n * interval)
+            val occ = nthWeekdayOfMonth(month, dow, ordinal)
+            n++
+            if (occ == null || occ.isBefore(start)) {
+                if (month.atEndOfMonth().isAfter(upTo)) return
+                continue
+            }
+            val pastUntil = until != null && occ.isAfter(until)
+            if (occ.isAfter(upTo) || pastUntil || emitted >= maxCount) return
+            emitted++
+            if (!onOccurrence(occ)) return
+        }
+    }
+
+    /** n-й день недели [dow] месяца [month]; ordinal>0 — с начала, -1 — последний; null если нет. */
+    private fun nthWeekdayOfMonth(month: java.time.YearMonth, dow: DayOfWeek, ordinal: Int): LocalDate? {
+        if (ordinal < 0) {
+            val last = month.atEndOfMonth()
+            val shift = (last.dayOfWeek.value - dow.value + 7) % 7
+            val candidate = last.minusDays(shift.toLong())
+            return if (java.time.YearMonth.from(candidate) == month) candidate else null
+        }
+        val first = month.atDay(1)
+        val shift = (dow.value - first.dayOfWeek.value + 7) % 7
+        val candidate = first.plusDays(shift.toLong() + (ordinal - 1) * 7L)
+        return if (java.time.YearMonth.from(candidate) == month) candidate else null
+    }
+
     /** WEEKLY с BYDAY: раскрываем выбранные дни недели в каждом интервал-блоке недель. */
     private inline fun forEachWeeklyByDay(
         rule: RecurrenceRule,

feature/calendar/src/main/java/ru/forbion/f7cloud/feature/calendar/RecurrenceRule.kt

@@ -9,6 +9,8 @@ data class RecurrenceRule(
     val interval: Int = 1,
     /** Дни недели для WEEKLY: MO..SU (порядок как в ICS). */
     val byDays: Set<String> = emptySet(),
+    /** Для MONTHLY с BYDAY=<n><день>: ординал (1..5 = n-й, -1 = последний). null — по числу месяца. */
+    val monthlyOrdinal: Int? = null,
     val endType: EndType = EndType.NEVER,
     val untilDate: LocalDate? = null,
     val count: Int = 10,
@@ -18,7 +20,10 @@ data class RecurrenceRule(
     fun toRrule(): String = buildString {
         append("FREQ=$freq")
         if (interval > 1) append(";INTERVAL=$interval")
-        if (freq == "WEEKLY" && byDays.isNotEmpty()) {
+        if (freq == "MONTHLY" && monthlyOrdinal != null && byDays.isNotEmpty()) {
+            // Месячный n-й день недели, напр. BYDAY=1MO (первый понедельник) — раньше терялся.
+            append(";BYDAY=$monthlyOrdinal${ICS_DAYS.first { it in byDays }}")
+        } else if (freq == "WEEKLY" && byDays.isNotEmpty()) {
             append(";BYDAY=${ICS_DAYS.filter { it in byDays }.joinToString(",")}")
         }
         when (endType) {
@@ -35,6 +40,7 @@ data class RecurrenceRule(
             "FR" to "Пт", "SA" to "Сб", "SU" to "Вс",
         )
         private val UNTIL_FMT = DateTimeFormatter.BASIC_ISO_DATE
+        private val BYDAY_ORDINAL = Regex("^(-?\\d+)(MO|TU|WE|TH|FR|SA|SU)$")
 
         /** Парсинг RRULE-строки; null для пустой/неразбираемой. */
         fun parse(rrule: String): RecurrenceRule? {
@@ -50,11 +56,16 @@ data class RecurrenceRule(
                 runCatching { LocalDate.parse(raw.take(8), UNTIL_FMT) }.getOrNull()
             }
             val count = parts["COUNT"]?.toIntOrNull()
+            val bydayTokens = parts["BYDAY"]?.split(',')?.map { it.trim().uppercase() }.orEmpty()
+            // Ординал для MONTHLY (BYDAY=1MO/-1FR): берём из первого токена с числовым префиксом.
+            val monthlyOrdinal = bydayTokens
+                .takeIf { freq == "MONTHLY" }
+                ?.firstNotNullOfOrNull { BYDAY_ORDINAL.find(it)?.groupValues?.get(1)?.toIntOrNull() }
             return RecurrenceRule(
                 freq = freq,
                 interval = parts["INTERVAL"]?.toIntOrNull()?.coerceAtLeast(1) ?: 1,
-                byDays = parts["BYDAY"]?.split(',')?.map { it.trim().takeLast(2).uppercase() }
+                byDays = bydayTokens.map { it.takeLast(2) }.filter { it in ICS_DAYS }.toSet(),
-                    ?.filter { it in ICS_DAYS }?.toSet().orEmpty(),
+                monthlyOrdinal = monthlyOrdinal,
                 endType = when {
                     until != null -> EndType.UNTIL
                     count != null -> EndType.COUNT

feature/calendar/src/test/java/ru/forbion/f7cloud/feature/calendar/CalendarRecurrenceTest.kt

@@ -80,6 +80,31 @@ class CalendarRecurrenceTest {
         assertFalse(occurs("FREQ=WEEKLY", "2026-07-01", "2026-07-10", span = 2, allDay = true))
     }
 
+    @Test fun monthly_nth_weekday_first_monday() {
+        // первый понедельник: июль'26 = 06, авг = 03, сен = 07
+        val r = "FREQ=MONTHLY;BYDAY=1MO"
+        assertTrue(occurs(r, "2026-07-06", "2026-07-06"))
+        assertTrue(occurs(r, "2026-07-06", "2026-08-03"))
+        assertTrue(occurs(r, "2026-07-06", "2026-09-07"))
+        assertFalse("второй понедельник — нет", occurs(r, "2026-07-06", "2026-07-13"))
+        assertFalse("число месяца, не день недели", occurs(r, "2026-07-06", "2026-08-06"))
+    }
+
+    @Test fun monthly_last_friday() {
+        // последняя пятница: июль'26 = 31, авг = 28
+        val r = "FREQ=MONTHLY;BYDAY=-1FR"
+        assertTrue(occurs(r, "2026-07-31", "2026-07-31"))
+        assertTrue(occurs(r, "2026-07-31", "2026-08-28"))
+        assertFalse(occurs(r, "2026-07-31", "2026-08-21"))
+    }
+
+    @Test fun byday_ordinal_round_trips_through_rrule() {
+        // раньше toRrule терял ординал (1MO → MO); теперь сохраняет.
+        assertEquals("FREQ=MONTHLY;BYDAY=1MO", rule("FREQ=MONTHLY;BYDAY=1MO").toRrule())
+        assertEquals("FREQ=MONTHLY;BYDAY=-1FR", rule("FREQ=MONTHLY;BYDAY=-1FR").toRrule())
+        assertEquals(1, rule("FREQ=MONTHLY;BYDAY=1MO").monthlyOrdinal)
+    }
+
     @Test fun range_listing() {
         val starts = CalendarRecurrence.occurrenceStartsInRange(
             rule = rule("FREQ=WEEKLY"),