P07-01-WX: 仕上がった天候の機能の受入：自然天候・雨・嵐・世界樹と成人客のマナ霧・上部の表示と予報・保存と移行（マナ炉の産出 120 を除く。P07-01 の補助の作業。原単位への加算 0）

scripts/environment/natural_weather_policy.gd

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+extends RefCounted
+
+## Approved initial weather values A13 (P07-01 SPEC sections 2 and 4). The
+## timeline stays a pure state model; this file owns the draw and the effects.
+const DAY_MINUTES := 1440
+const DRAW_MINUTE_OF_DAY := 360
+const FIRST_START_MINUTE_OF_DAY := 360
+const START_SLOT_MINUTES := 30
+const START_SLOTS := 29
+## Rolls 0..99: clear 0-59, rain 60-84, mana fog 85-94, storm 95-99.
+const CLEAR_BELOW := 60
+const RAIN_BELOW := 85
+const FOG_BELOW := 95
+const DURATION_MINUTES := {&"rain": 360, &"mana_fog": 240, &"storm": 120}
+const RAIN_ARRIVAL_PERCENT := 50
+const RAIN_HOLD_MAX_MINUTES := 240
+const FOG_MANA_NUMERATOR := 12
+const FOG_MANA_DENOMINATOR := 10
+const FOG_INTIMACY_NUMERATOR := 3
+const FOG_INTIMACY_DENOMINATOR := 2
+
+static func is_draw_minute(absolute_minute: int) -> bool:
+	return absolute_minute >= 0 and posmod(absolute_minute, DAY_MINUTES) == DRAW_MINUTE_OF_DAY
+
+static func day_of(absolute_minute: int) -> int:
+	return int(floor(float(absolute_minute) / DAY_MINUTES)) if absolute_minute >= 0 else -1
+
+## One draw per day from the saved weather stream. A clear day consumes one
+## roll; other days also consume one start-slot roll.
+static func draw(rng: DeterministicRng, day: int) -> Dictionary:
+	var roll := rng.randi_range(0, 99)
+	var kind: StringName = &"clear"
+	if roll >= FOG_BELOW:
+		kind = &"storm"
+	elif roll >= RAIN_BELOW:
+		kind = &"mana_fog"
+	elif roll >= CLEAR_BELOW:
+		kind = &"rain"
+	if kind == &"clear":
+		return {&"day": day, &"kind": kind, &"roll": roll, &"slot": -1, &"start": -1, &"end": -1}
+	var slot := rng.randi_range(0, START_SLOTS - 1)
+	var start := day * DAY_MINUTES + FIRST_START_MINUTE_OF_DAY + slot * START_SLOT_MINUTES
+	return {&"day": day, &"kind": kind, &"roll": roll, &"slot": slot,
+		&"start": start, &"end": start + int(DURATION_MINUTES[kind])}
+
+static func arrival_percent(kind: StringName) -> int:
+	return RAIN_ARRIVAL_PERCENT if kind == &"rain" else 100
+
+static func mana_yield(base_amount: int, kind: StringName) -> int:
+	if kind != &"mana_fog":
+		return base_amount
+	return int(floor(float(base_amount * FOG_MANA_NUMERATOR) / FOG_MANA_DENOMINATOR))
+
+static func fog_intimacy_increase(increase: int) -> int:
+	if increase <= 0:
+		return increase
+	return int(floor(float(increase * FOG_INTIMACY_NUMERATOR) / FOG_INTIMACY_DENOMINATOR))
+
+## Japanese HUD guidance for the current kind (SPEC section 4.6).
+static func effect_text(kind: StringName) -> String:
+	match kind:
+		&"rain":
+			return "雨: 新規来客が半分になり、帰る予定の客は雨が止むまで（最大4時間）残ります。"
+		&"storm":
+			return "嵐: 新規来客はありません。館内の客は残ります。"
+		&"mana_fog":
+			return "マナ霧: 世界樹のマナ産出が1.2倍、成人確認済みの客の性欲の増え方が1.5倍になります。"
+	return "晴れ: 天候の影響はありません。"