P05-02: 全費目と資金区分：表金・裏金、維持費未払い、仕入れ、人件費、元本、利息、税の帳簿への接続（原 P05-02 の完了の条件）

scripts/economy/facility_upkeep_settlement.gd

@@ -65,6 +65,33 @@ func settle(period: Dictionary, economy: EconomyService) -> Dictionary:
 	return {&"ok": true, &"replayed": false, &"receipt": receipt.duplicate(true), &"transaction_id": transaction_id}
 
 
+## Whole Gold that settling these closed periods would owe (arrears included),
+## planned with no cash; -1 if a period is invalid or already settled. Nothing changes.
+func preview_debt(periods: Array) -> int:
+	var arrears := _arrears.duplicate()
+	var fractions := _fractions.duplicate()
+	var last_end := int(_receipts[-1].period.period_end) if not _receipts.is_empty() else -1
+	var candidate := FacilityUpkeepSettlement.new()
+	for raw: Variant in periods:
+		if not raw is Dictionary:
+			return -1
+		var canonical := _parse_period(raw)
+		if canonical.is_empty() or (last_end >= 0 and canonical.period_start != last_end):
+			return -1
+		candidate._arrears = arrears
+		candidate._fractions = fractions
+		var plan := candidate._plan(canonical, 0)
+		if not plan[&"ok"]:
+			return -1
+		arrears = plan.arrears
+		fractions = plan.fractions
+		last_end = canonical.period_end
+	var debt := 0
+	for amount: int in arrears.values():
+		debt += amount
+	return debt
+
+
 func get_arrears_through(minute: int) -> int:
 	var low := 0
 	var high := _receipts.size()

scripts/economy/finance_policy.gd

@@ -0,0 +1,86 @@
+class_name FinancePolicy
+extends RefCounted
+
+## Front (表金) and hidden (裏金) funds, the World Tree rank tax and dark bank interest.
+## Values are the user-approved initial test values (decisions A09-A12, 2026-10-23).
+## The front fund keeps the existing PLAYER_CASH account; saves made before the split
+## carry no hidden fund account and are read with every Gold as front funds (A12).
+
+const FRONT_CASH: StringName = &"PLAYER_CASH"
+const BACK_CASH: StringName = &"BACK_CASH"
+const RANK_TAX_EXPENSE: StringName = &"RANK_TAX_EXPENSE"
+const RANK_TAX_PAYABLE: StringName = &"RANK_TAX_PAYABLE"
+const LOAN_INTEREST_EXPENSE: StringName = &"LOAN_INTEREST_EXPENSE"
+const LOAN_INTEREST_PAYABLE: StringName = &"LOAN_INTEREST_PAYABLE"
+const LOAN_LIABILITY_PREFIX := "LOAN_LIABILITY:"
+
+## A10: 10% of the closed day's sales (front + hidden), whole Gold rounded down.
+const RANK_TAX_PERCENT := 10
+## A11: 1% of the outstanding principal per day, whole Gold rounded down.
+const LOAN_INTEREST_PERCENT_PER_DAY := 1
+
+## Services of facilities with one of these tags earn hidden funds (原本: 成人施設、
+## カジノ、脅迫金、ユニット売却は裏の収益). Every other service earns front funds.
+const BACK_FUND_TAGS: Array[StringName] = [&"restricted_service", &"adult_only"]
+
+## Ledger categories. Accruals are expenses of the closed day; payments, top-ups and
+## the payable balances are not income or expense.
+const TOP_UP_CATEGORY: StringName = &"BACK_FUND_TOP_UP"
+const RANK_TAX_CATEGORY: StringName = &"RANK_TAX"
+const RANK_TAX_PAYMENT_CATEGORY: StringName = &"RANK_TAX_PAYMENT"
+const LOAN_INTEREST_CATEGORY: StringName = &"LOAN_INTEREST"
+const LOAN_INTEREST_PAYMENT_CATEGORY: StringName = &"LOAN_INTEREST_PAYMENT"
+const NON_PROFIT_CATEGORIES: Array[StringName] = [TOP_UP_CATEGORY, RANK_TAX_PAYMENT_CATEGORY, LOAN_INTEREST_PAYMENT_CATEGORY]
+
+
+static func rank_tax(sales: int) -> int:
+	return maxi(sales, 0) / 100 * RANK_TAX_PERCENT + maxi(sales, 0) % 100 * RANK_TAX_PERCENT / 100
+
+
+static func loan_interest(outstanding_principal: int) -> int:
+	return maxi(outstanding_principal, 0) / 100 * LOAN_INTEREST_PERCENT_PER_DAY \
+		+ maxi(outstanding_principal, 0) % 100 * LOAN_INTEREST_PERCENT_PER_DAY / 100
+
+
+static func is_back_fund_service(tags: Array) -> bool:
+	for tag: StringName in BACK_FUND_TAGS:
+		if tag in tags:
+			return true
+	return false
+
+
+## Accounts of the split funds. A save without BACK_CASH predates the split and must
+## not hold any of the other accounts either; they are then created empty (A12).
+## Any other partial or incompatible set is rejected.
+static func prepare_accounts(economy: EconomyService) -> bool:
+	if economy == null or not economy.has_account(FRONT_CASH) or economy.account_allows_negative(FRONT_CASH):
+		return false
+	var expected := {
+		BACK_CASH: false, RANK_TAX_EXPENSE: false, LOAN_INTEREST_EXPENSE: false,
+		RANK_TAX_PAYABLE: true, LOAN_INTEREST_PAYABLE: true,
+	}
+	if not economy.has_account(BACK_CASH):
+		for account_id: StringName in expected:
+			if economy.has_account(account_id):
+				return false
+		for account_id: StringName in expected:
+			if not economy.register_account(account_id, bool(expected[account_id])):
+				return false
+		return true
+	for account_id: StringName in expected:
+		if not economy.has_account(account_id) \
+				or economy.account_allows_negative(account_id) != bool(expected[account_id]):
+			return false
+	return true
+
+
+static func outstanding_principal(economy: EconomyService) -> int:
+	var total := 0
+	for account: Dictionary in economy.get_accounts():
+		if String(account[&"account_id"]).begins_with(LOAN_LIABILITY_PREFIX):
+			total += -int(account[&"balance"])
+	return total
+
+
+static func available_funds(economy: EconomyService) -> int:
+	return economy.get_balance(FRONT_CASH) + economy.get_balance(BACK_CASH)

scripts/economy/finance_policy.gd.uid

@@ -0,0 +1 @@
+uid://l14tq0avw0ux