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

@@ -43,6 +43,30 @@ static func draw(rng: DeterministicRng, day: int) -> Dictionary:
 	return {&"day": day, &"kind": kind, &"roll": roll, &"slot": slot,
 		&"start": start, &"end": start + int(DURATION_MINUTES[kind])}
 
+## A saved day's draw must be this rule's own result (SPEC section 5.3): the roll
+## picks the kind, a clear day has no slot, and any other day starts on its slot
+## and lasts its kind's duration. An empty draw (no day drawn yet) is consistent.
+static func is_consistent_draw(draw: Dictionary) -> bool:
+	if draw.is_empty():
+		return true
+	var roll := int(draw[&"roll"])
+	var kind := StringName(draw[&"kind"])
+	var expected: StringName = &"clear"
+	if roll >= FOG_BELOW:
+		expected = &"storm"
+	elif roll >= RAIN_BELOW:
+		expected = &"mana_fog"
+	elif roll >= CLEAR_BELOW:
+		expected = &"rain"
+	if kind != expected:
+		return false
+	if kind == &"clear":
+		return int(draw[&"slot"]) == -1 and int(draw[&"start"]) == -1 and int(draw[&"end"]) == -1
+	var slot := int(draw[&"slot"])
+	var start := int(draw[&"day"]) * DAY_MINUTES + FIRST_START_MINUTE_OF_DAY + slot * START_SLOT_MINUTES
+	return slot >= 0 and slot < START_SLOTS and int(draw[&"start"]) == start \
+		and int(draw[&"end"]) == start + int(DURATION_MINUTES[kind])
+
 static func arrival_percent(kind: StringName) -> int:
 	return RAIN_ARRIVAL_PERCENT if kind == &"rain" else 100