test: expand PricingEngine tests + update CryptoBot payment tests

- Add 45 unit tests covering tariff/classic modes, discounts, edge cases
- Update CryptoBot payment tests for new PricingEngine integration
- Add original_total identity tests for both pricing modes

CONTRIBUTING.md

@@ -197,28 +197,17 @@ async def create_subscription(
 ### Документация кода
 
 ```python
-async def calculate_subscription_price(
-    period_days: int,
-    traffic_gb: int,
-    devices_count: int,
-    servers_count: int
-) -> int:
-    """
-    Рассчитывает стоимость подписки.
-    
-    Args:
-        period_days: Период подписки в днях
-        traffic_gb: Лимит трафика в ГБ (0 = безлимит)
-        devices_count: Количество устройств
-        servers_count: Количество серверов
-        
-    Returns:
-        Стоимость в копейках
-        
-    Raises:
-        ValueError: Если переданы некорректные параметры
-    """
-    # implementation
+from app.services.pricing_engine import PricingEngine
+
+pricing = PricingEngine.calculate_renewal_price(
+    subscription=subscription,
+    period_days=30,
+    user=user,
+)
+# pricing.final_total — стоимость в копейках
+# pricing.original_total — цена до скидок
+# pricing.promo_group_discount — скидка промогруппы
+# pricing.promo_offer_discount — скидка промо-оффера
 ```
 
 ### Обработка ошибок
@@ -341,20 +330,18 @@ python main.py
 ### Тестирование компонентов
 
 ```python
-# tests/test_subscription_service.py
+# tests/services/test_pricing_engine.py
 import pytest
-from app.services.subscription_service import SubscriptionService
+from app.services.pricing_engine import PricingEngine
 
-@pytest.mark.asyncio
-async def test_calculate_price():
-    price = await SubscriptionService.calculate_subscription_price(
+def test_calculate_renewal_price():
+    pricing = PricingEngine.calculate_renewal_price(
+        subscription=mock_subscription,
         period_days=30,
-        traffic_gb=100,
-        devices_count=3,
-        servers_count=1
+        user=mock_user,
     )
-    assert price > 0
-    assert isinstance(price, int)
+    assert pricing.final_total > 0
+    assert isinstance(pricing.final_total, int)
 ```
 
 ### Integration тесты

tests/test_miniapp_payments.py

@@ -20,6 +20,7 @@ os.environ.setdefault('BOT_TOKEN', 'test-token')
 from app.config import settings
 from app.database.models import PaymentMethod
 from app.services.payment.cryptobot import CryptoBotPaymentMixin
+from app.services.pricing_engine import PricingEngine
 from app.services.subscription_renewal_service import (
     SubscriptionRenewalPricing,
     SubscriptionRenewalResult,
@@ -348,7 +349,7 @@ async def test_cryptobot_renewal_uses_pricing_snapshot(monkeypatch):
     module = sys.modules['app.services.payment.cryptobot']
     mixin = CryptoBotPaymentMixin()
 
-    subscription = types.SimpleNamespace(id=77, connected_squads=[], traffic_limit_gb=100, device_limit=5)
+    subscription = types.SimpleNamespace(id=77, connected_squads=[], traffic_limit_gb=100, device_limit=5, tariff=None, tariff_id=None)
     user = types.SimpleNamespace(id=5, balance_kopeks=7000, subscription=subscription)
 
     pricing_model = SubscriptionRenewalPricing(
@@ -385,9 +386,9 @@ async def test_cryptobot_renewal_uses_pricing_snapshot(monkeypatch):
     )
 
     async def fail_calculate(*args, **kwargs):
-        raise AssertionError('calculate_pricing should not be called when snapshot is present')
+        raise AssertionError('PricingEngine.calculate_renewal_price should not be called when snapshot is present')
 
-    monkeypatch.setattr(module.renewal_service, 'calculate_pricing', fail_calculate)
+    monkeypatch.setattr(PricingEngine, 'calculate_renewal_price', fail_calculate)
 
     captured: dict[str, Any] = {}
 
@@ -431,7 +432,7 @@ async def test_cryptobot_renewal_accepts_changed_pricing_without_snapshot(monkey
     module = sys.modules['app.services.payment.cryptobot']
     mixin = CryptoBotPaymentMixin()
 
-    subscription = types.SimpleNamespace(id=55, connected_squads=[], traffic_limit_gb=50, device_limit=3)
+    subscription = types.SimpleNamespace(id=55, connected_squads=[], traffic_limit_gb=50, device_limit=3, tariff=None, tariff_id=None)
     user = types.SimpleNamespace(id=8, balance_kopeks=4000, subscription=subscription)
 
     descriptor = build_payment_descriptor(
@@ -451,25 +452,26 @@ async def test_cryptobot_renewal_accepts_changed_pricing_without_snapshot(monkey
         sys.modules, 'app.services.payment_service', types.SimpleNamespace(get_user_by_id=fake_get_user_by_id)
     )
 
+    # Recalculated price is LOWER than descriptor — user benefits, should proceed
     recalculated_pricing = SubscriptionRenewalPricing(
         period_days=30,
         period_id='days:30',
         months=1,
-        base_original_total=5200,
-        discounted_total=5200,
-        final_total=5200,
+        base_original_total=4800,
+        discounted_total=4800,
+        final_total=4800,
         promo_discount_value=0,
         promo_discount_percent=0,
         overall_discount_percent=0,
-        per_month=5200,
+        per_month=4800,
         server_ids=[],
         details={},
     )
 
-    async def fake_calculate(db, u, sub, period):
+    async def fake_calculate(self, db, sub, period_days, *, user=None):
         return recalculated_pricing
 
-    monkeypatch.setattr(module.renewal_service, 'calculate_pricing', fake_calculate)
+    monkeypatch.setattr(PricingEngine, 'calculate_renewal_price', fake_calculate)
 
     captured: dict[str, Any] = {}
 
@@ -499,8 +501,10 @@ async def test_cryptobot_renewal_accepts_changed_pricing_without_snapshot(monkey
     )
 
     assert result is True
-    assert captured['pricing'].final_total == 5000
-    assert captured['charge'] == 4000
+    # With C-4 fix: recalculated price (4800) < descriptor (5000) → use recalculated
+    assert captured['pricing'].final_total == 4800
+    # M-5 fix: required_balance = max(0, final_total - missing) = max(0, 4800 - 1000) = 3800
+    assert captured['charge'] == 3800
 
 
 @pytest.mark.anyio('asyncio')
@@ -508,7 +512,7 @@ async def test_cryptobot_webhook_uses_inline_payload_when_db_missing(monkeypatch
     module = sys.modules['app.services.payment.cryptobot']
     mixin = CryptoBotPaymentMixin()
 
-    subscription = types.SimpleNamespace(id=91, connected_squads=[], traffic_limit_gb=80, device_limit=4)
+    subscription = types.SimpleNamespace(id=91, connected_squads=[], traffic_limit_gb=80, device_limit=4, tariff=None, tariff_id=None)
     user = types.SimpleNamespace(id=21, balance_kopeks=6000, subscription=subscription)
 
     pricing_model = SubscriptionRenewalPricing(
@@ -560,9 +564,9 @@ async def test_cryptobot_webhook_uses_inline_payload_when_db_missing(monkeypatch
     )
 
     async def fail_calculate(*args, **kwargs):
-        raise AssertionError('calculate_pricing should not be called')
+        raise AssertionError('PricingEngine.calculate_renewal_price should not be called')
 
-    monkeypatch.setattr(module.renewal_service, 'calculate_pricing', fail_calculate)
+    monkeypatch.setattr(PricingEngine, 'calculate_renewal_price', fail_calculate)
 
     captured: dict[str, Any] = {}
 

tests/test_pricing_engine.py

@@ -59,12 +59,35 @@ class TestStackedDiscounts:
         assert g_val == 0
         assert o_val == 1500
 
+    def test_only_group(self):
+        result, gd, od = PricingEngine.apply_stacked_discounts(10000, 20, 0)
+        assert result == 8000
+        assert gd == 2000
+        assert od == 0
+
+    def test_both_100_percent(self):
+        result, gd, od = PricingEngine.apply_stacked_discounts(10000, 100, 100)
+        assert result == 0
+        assert gd == 10000
+        assert od == 0  # offer discount on 0 is 0
+
 
 from unittest.mock import AsyncMock, MagicMock, patch
 
 
-def _make_server(price_kopeks=5000, is_available=True, is_full=False, allowed_promo_groups=None):
+_server_id_counter = 0
+
+
+def _make_server(
+    price_kopeks=5000, is_available=True, is_full=False, allowed_promo_groups=None, server_id=None, squad_uuid=None
+):
+    global _server_id_counter
+    if server_id is None:
+        _server_id_counter += 1
+        server_id = _server_id_counter
     server = MagicMock()
+    server.id = server_id
+    server.squad_uuid = squad_uuid
     server.price_kopeks = price_kopeks
     server.is_available = is_available
     server.is_full = is_full
@@ -77,8 +100,8 @@ class TestCalculateServersPrice:
     async def test_available_server(self):
         engine = PricingEngine()
         db = AsyncMock()
-        server = _make_server(price_kopeks=5000)
-        with patch('app.services.pricing_engine.get_server_squad_by_uuid', return_value=server):
+        server = _make_server(price_kopeks=5000, squad_uuid='uuid-1')
+        with patch('app.services.pricing_engine.get_server_squads_by_uuids', return_value=[server]):
             total, details = await engine._calculate_servers_price(['uuid-1'], db, promo_group_id=None)
         assert total == 5000
         assert len(details) == 1
@@ -88,8 +111,8 @@ class TestCalculateServersPrice:
     async def test_unavailable_server_uses_real_price(self):
         engine = PricingEngine()
         db = AsyncMock()
-        server = _make_server(price_kopeks=7000, is_available=False)
-        with patch('app.services.pricing_engine.get_server_squad_by_uuid', return_value=server):
+        server = _make_server(price_kopeks=7000, is_available=False, squad_uuid='uuid-1')
+        with patch('app.services.pricing_engine.get_server_squads_by_uuids', return_value=[server]):
             total, details = await engine._calculate_servers_price(['uuid-1'], db, promo_group_id=None)
         assert total == 7000  # NOT 0!
         assert details[0]['status'] == 'unavailable'
@@ -98,8 +121,8 @@ class TestCalculateServersPrice:
     async def test_full_server_uses_real_price(self):
         engine = PricingEngine()
         db = AsyncMock()
-        server = _make_server(price_kopeks=3000, is_full=True)
-        with patch('app.services.pricing_engine.get_server_squad_by_uuid', return_value=server):
+        server = _make_server(price_kopeks=3000, is_full=True, squad_uuid='uuid-1')
+        with patch('app.services.pricing_engine.get_server_squads_by_uuids', return_value=[server]):
             total, details = await engine._calculate_servers_price(['uuid-1'], db, promo_group_id=None)
         assert total == 3000  # NOT 0!
 
@@ -107,7 +130,7 @@ class TestCalculateServersPrice:
     async def test_server_not_found_zero_price(self):
         engine = PricingEngine()
         db = AsyncMock()
-        with patch('app.services.pricing_engine.get_server_squad_by_uuid', return_value=None):
+        with patch('app.services.pricing_engine.get_server_squads_by_uuids', return_value=[]):
             total, details = await engine._calculate_servers_price(['uuid-orphan'], db, promo_group_id=None)
         assert total == 0
         assert details[0]['status'] == 'not_found'
@@ -116,12 +139,51 @@ class TestCalculateServersPrice:
     async def test_multiple_servers(self):
         engine = PricingEngine()
         db = AsyncMock()
-        s1 = _make_server(price_kopeks=5000)
-        s2 = _make_server(price_kopeks=3000, is_available=False)
-        with patch('app.services.pricing_engine.get_server_squad_by_uuid', side_effect=[s1, s2]):
+        s1 = _make_server(price_kopeks=5000, squad_uuid='uuid-1')
+        s2 = _make_server(price_kopeks=3000, is_available=False, squad_uuid='uuid-2')
+        with patch('app.services.pricing_engine.get_server_squads_by_uuids', return_value=[s1, s2]):
             total, details = await engine._calculate_servers_price(['uuid-1', 'uuid-2'], db, promo_group_id=None)
         assert total == 8000
 
+    @pytest.mark.asyncio
+    async def test_server_ids_and_prices_alignment_with_not_found(self):
+        """Verify server_ids and servers_individual_prices have same length when some servers are not found."""
+        engine = PricingEngine()
+        db = AsyncMock()
+        s1 = _make_server(price_kopeks=5000, server_id=10, squad_uuid='uuid-1')
+        s3 = _make_server(price_kopeks=3000, server_id=30, squad_uuid='uuid-3')
+        # uuid-orphan not in batch result — should be excluded from BOTH lists
+        with patch('app.services.pricing_engine.get_server_squads_by_uuids', return_value=[s1, s3]):
+            total, details = await engine._calculate_servers_price(
+                ['uuid-1', 'uuid-orphan', 'uuid-3'], db, promo_group_id=None
+            )
+        assert total == 8000  # 5000 + 0 + 3000
+        assert len(details) == 3
+        # Verify id fields
+        assert details[0]['id'] == 10
+        assert details[1]['id'] is None
+        assert details[2]['id'] == 30
+
+    @pytest.mark.asyncio
+    async def test_db_exception_path(self):
+        """Verify batch DB exception returns price=0 and status=error for all UUIDs."""
+        engine = PricingEngine()
+        db = AsyncMock()
+        with patch('app.services.pricing_engine.get_server_squads_by_uuids', side_effect=RuntimeError('DB error')):
+            total, details = await engine._calculate_servers_price(['uuid-1'], db, promo_group_id=None)
+        assert total == 0
+        assert details[0]['status'] == 'error'
+        assert details[0]['id'] is None
+
+    @pytest.mark.asyncio
+    async def test_empty_uuids_returns_empty(self):
+        """Verify empty UUIDs list returns 0 total and empty details."""
+        engine = PricingEngine()
+        db = AsyncMock()
+        total, details = await engine._calculate_servers_price([], db, promo_group_id=None)
+        assert total == 0
+        assert details == []
+
 
 class TestCalculateTrafficPrice:
     def test_base_only(self):
@@ -163,6 +225,7 @@ class TestCalculateRenewalPriceTariffMode:
         subscription.tariff = MagicMock()
         subscription.tariff.period_prices = {'30': 19000}
         subscription.tariff.device_limit = 2
+        subscription.tariff.device_price_kopeks = None
         subscription.tariff.id = 2
         subscription.device_limit = 2
         subscription.connected_squads = []
@@ -190,6 +253,7 @@ class TestCalculateRenewalPriceTariffMode:
         subscription.tariff = MagicMock()
         subscription.tariff.period_prices = {'30': 19000}
         subscription.tariff.device_limit = 2
+        subscription.tariff.device_price_kopeks = None
         subscription.tariff.id = 2
         subscription.device_limit = 4
         subscription.connected_squads = []
@@ -208,6 +272,30 @@ class TestCalculateRenewalPriceTariffMode:
         assert result.devices_price == 10000
         assert result.final_total == 29000
 
+    @pytest.mark.asyncio
+    async def test_tariff_device_price_from_tariff(self):
+        """When tariff has device_price_kopeks set, use it instead of settings."""
+        engine = PricingEngine()
+        db = AsyncMock()
+        subscription = MagicMock()
+        subscription.tariff_id = 2
+        subscription.tariff = MagicMock()
+        subscription.tariff.period_prices = {'30': 10000}
+        subscription.tariff.device_limit = 2
+        subscription.tariff.device_price_kopeks = 3000  # tariff-specific price
+        subscription.tariff.id = 2
+        subscription.device_limit = 4  # 2 extra devices
+        user = MagicMock()
+        user.promo_group = None
+        with (
+            patch('app.services.pricing_engine.get_user_active_promo_discount_percent', return_value=0),
+            patch('app.services.pricing_engine.settings') as ms,
+        ):
+            ms.PRICE_PER_DEVICE = 5000  # should NOT be used
+            result = await engine.calculate_renewal_price(db, subscription, 30, user=user)
+        assert result.devices_price == 6000  # 2 extra × 3000 (tariff price)
+        assert result.final_total == 16000  # 10000 + 6000
+
     @pytest.mark.asyncio
     async def test_tariff_with_discounts(self):
         engine = PricingEngine()
@@ -217,6 +305,7 @@ class TestCalculateRenewalPriceTariffMode:
         subscription.tariff = MagicMock()
         subscription.tariff.period_prices = {'30': 20000}
         subscription.tariff.device_limit = 1
+        subscription.tariff.device_price_kopeks = None
         subscription.tariff.id = 1
         subscription.device_limit = 1
         promo_group = MagicMock()
@@ -244,6 +333,7 @@ class TestCalculateRenewalPriceTariffMode:
         subscription.tariff = MagicMock()
         subscription.tariff.period_prices = {'30': 19000}
         subscription.tariff.device_limit = 1
+        subscription.tariff.device_price_kopeks = None
         subscription.tariff.id = 1
         subscription.device_limit = 1
         user = MagicMock()
@@ -257,6 +347,30 @@ class TestCalculateRenewalPriceTariffMode:
         assert result.base_price == 0
         assert result.final_total == 0
 
+    @pytest.mark.asyncio
+    async def test_tariff_device_limit_below_tariff_included(self):
+        """When subscription device_limit < tariff device_limit, extra_devices is 0 (not negative)."""
+        engine = PricingEngine()
+        db = AsyncMock()
+        tariff = MagicMock()
+        tariff.id = 1
+        tariff.period_prices = {'30': 10000}
+        tariff.device_price_kopeks = 5000
+        tariff.device_limit = 5
+        sub = MagicMock()
+        sub.tariff_id = 1
+        sub.tariff = tariff
+        sub.device_limit = 2  # less than tariff's 5
+        user = MagicMock()
+        user.promo_group = None
+
+        with patch('app.services.pricing_engine.get_user_active_promo_discount_percent', return_value=0):
+            result = await engine.calculate_renewal_price(db, sub, 30, user=user)
+
+        assert result.devices_price == 0
+        assert result.final_total == 10000
+        assert result.breakdown.get('extra_devices') == 0
+
 
 class TestCalculateRenewalPriceClassicMode:
     @pytest.mark.asyncio
@@ -275,9 +389,9 @@ class TestCalculateRenewalPriceClassicMode:
         user.promo_group_id = None
         user.promo_offer_discount_percent = 0
         user.promo_offer_expires_at = None
-        server = _make_server(price_kopeks=5000)
+        server = _make_server(price_kopeks=5000, squad_uuid='uuid-1')
         with (
-            patch('app.services.pricing_engine.get_server_squad_by_uuid', return_value=server),
+            patch('app.services.pricing_engine.get_server_squads_by_uuids', return_value=[server]),
             patch('app.services.pricing_engine.get_user_active_promo_discount_percent', return_value=0),
             patch('app.services.pricing_engine.settings') as ms,
             patch('app.services.pricing_engine.CLASSIC_PERIOD_PRICES', {30: 29000}),
@@ -286,6 +400,7 @@ class TestCalculateRenewalPriceClassicMode:
             ms.get_traffic_price.return_value = 3000
             ms.PRICE_PER_DEVICE = 0
             ms.DEFAULT_DEVICE_LIMIT = 2
+            ms.is_traffic_fixed.return_value = False
             result = await engine.calculate_renewal_price(db, subscription, 30, user=user)
         assert result.is_tariff_mode is False
         assert result.base_price == 29000
@@ -321,6 +436,7 @@ class TestCalculateRenewalPriceClassicMode:
             ms.get_traffic_price.return_value = 0
             ms.PRICE_PER_DEVICE = 0
             ms.DEFAULT_DEVICE_LIMIT = 2
+            ms.is_traffic_fixed.return_value = False
             result = await engine.calculate_renewal_price(db, subscription, 30, user=user)
         assert result.final_total == 7200
         assert result.promo_group_discount == 2000
@@ -350,6 +466,7 @@ class TestCalculateRenewalPriceClassicMode:
             ms.get_traffic_price.return_value = 0
             ms.PRICE_PER_DEVICE = 0
             ms.DEFAULT_DEVICE_LIMIT = 1
+            ms.is_traffic_fixed.return_value = False
             result = await engine.calculate_renewal_price(db, subscription, 30, user=user)
         assert result.base_price == 99000
         assert result.final_total == 99000
@@ -377,7 +494,373 @@ class TestCalculateRenewalPriceClassicMode:
             ms.get_traffic_price.return_value = 0
             ms.PRICE_PER_DEVICE = 3000
             ms.DEFAULT_DEVICE_LIMIT = 2
+            ms.is_traffic_fixed.return_value = False
             result = await engine.calculate_renewal_price(db, subscription, 30, user=user)
         # 5 - 2 = 3 extra devices * 3000 = 9000
         assert result.devices_price == 9000
         assert result.final_total == 19000
+
+    @pytest.mark.asyncio
+    async def test_classic_breakdown_server_ids_and_prices_alignment(self):
+        """Verify server_ids and servers_individual_prices have same length when orphaned UUIDs present."""
+        engine = PricingEngine()
+        db = AsyncMock()
+        subscription = MagicMock()
+        subscription.tariff_id = None
+        subscription.tariff = None
+        subscription.connected_squads = ['uuid-found', 'uuid-orphan', 'uuid-found2']
+        subscription.traffic_limit_gb = 0
+        subscription.purchased_traffic_gb = 0
+        subscription.device_limit = 1
+        user = MagicMock()
+        user.promo_group = None
+        user.promo_group_id = None
+        s1 = _make_server(price_kopeks=5000, server_id=10, squad_uuid='uuid-found')
+        s3 = _make_server(price_kopeks=3000, server_id=30, squad_uuid='uuid-found2')
+        with (
+            patch(
+                'app.services.pricing_engine.get_server_squads_by_uuids',
+                return_value=[s1, s3],
+            ),
+            patch('app.services.pricing_engine.get_user_active_promo_discount_percent', return_value=0),
+            patch('app.services.pricing_engine.settings') as ms,
+            patch('app.services.pricing_engine.CLASSIC_PERIOD_PRICES', {30: 10000}),
+            patch('app.services.pricing_engine.PERIOD_PRICES', {}),
+        ):
+            ms.get_traffic_price.return_value = 0
+            ms.PRICE_PER_DEVICE = 0
+            ms.DEFAULT_DEVICE_LIMIT = 1
+            ms.is_traffic_fixed.return_value = False
+            result = await engine.calculate_renewal_price(db, subscription, 30, user=user)
+        # Verify breakdown alignment — both lists must have same length
+        ids = result.breakdown['server_ids']
+        prices = result.breakdown['servers_individual_prices']
+        assert len(ids) == len(prices), f'server_ids({len(ids)}) != prices({len(prices)})'
+        assert ids == [10, 30]
+        assert prices == [5000, 3000]
+        # Total servers_price includes only found servers
+        assert result.servers_price == 8000
+
+    @pytest.mark.asyncio
+    async def test_classic_fixed_traffic_ignores_subscription_values(self):
+        """When is_traffic_fixed() is True, use fixed limit and zero purchased."""
+        engine = PricingEngine()
+        db = AsyncMock()
+        subscription = MagicMock()
+        subscription.tariff_id = None
+        subscription.tariff = None
+        subscription.connected_squads = []
+        subscription.traffic_limit_gb = 999  # should be ignored
+        subscription.purchased_traffic_gb = 500  # should be ignored
+        subscription.device_limit = 1
+        user = MagicMock()
+        user.promo_group = None
+        user.promo_group_id = None
+        with (
+            patch('app.services.pricing_engine.get_user_active_promo_discount_percent', return_value=0),
+            patch('app.services.pricing_engine.settings') as ms,
+            patch('app.services.pricing_engine.CLASSIC_PERIOD_PRICES', {30: 10000}),
+            patch('app.services.pricing_engine.PERIOD_PRICES', {}),
+        ):
+            ms.is_traffic_fixed.return_value = True
+            ms.get_fixed_traffic_limit.return_value = 50
+            ms.get_traffic_price.side_effect = lambda gb: {50: 4000}.get(gb, 0)
+            ms.PRICE_PER_DEVICE = 0
+            ms.DEFAULT_DEVICE_LIMIT = 1
+            result = await engine.calculate_renewal_price(db, subscription, 30, user=user)
+        assert result.traffic_price == 4000
+        assert result.breakdown['purchased_traffic_gb'] == 0
+
+    @pytest.mark.asyncio
+    async def test_classic_default_traffic_limit_when_none(self):
+        """When subscription.traffic_limit_gb is None, use DEFAULT_TRAFFIC_LIMIT_GB."""
+        engine = PricingEngine()
+        db = AsyncMock()
+        subscription = MagicMock()
+        subscription.tariff_id = None
+        subscription.tariff = None
+        subscription.connected_squads = []
+        subscription.traffic_limit_gb = None  # should fallback to default
+        subscription.purchased_traffic_gb = 0
+        subscription.device_limit = 1
+        user = MagicMock()
+        user.promo_group = None
+        user.promo_group_id = None
+        with (
+            patch('app.services.pricing_engine.get_user_active_promo_discount_percent', return_value=0),
+            patch('app.services.pricing_engine.settings') as ms,
+            patch('app.services.pricing_engine.CLASSIC_PERIOD_PRICES', {30: 10000}),
+            patch('app.services.pricing_engine.PERIOD_PRICES', {}),
+        ):
+            ms.is_traffic_fixed.return_value = False
+            ms.DEFAULT_TRAFFIC_LIMIT_GB = 50
+            ms.get_traffic_price.side_effect = lambda gb: {50: 4000}.get(gb, 0)
+            ms.PRICE_PER_DEVICE = 0
+            ms.DEFAULT_DEVICE_LIMIT = 1
+            result = await engine.calculate_renewal_price(db, subscription, 30, user=user)
+        assert result.traffic_price == 4000
+
+    @pytest.mark.asyncio
+    async def test_classic_multi_month_period(self):
+        """90-day period multiplies monthly prices by 3."""
+        engine = PricingEngine()
+        db = AsyncMock()
+        sub = MagicMock()
+        sub.tariff_id = None
+        sub.tariff = None
+        sub.connected_squads = ['uuid-s1']
+        sub.traffic_limit_gb = 50
+        sub.purchased_traffic_gb = 0
+        sub.device_limit = 1
+        user = MagicMock()
+        user.promo_group = None
+        user.promo_group_id = None
+
+        server = _make_server(price_kopeks=3000, squad_uuid='uuid-s1')
+
+        with (
+            patch('app.services.pricing_engine.get_server_squads_by_uuids', return_value=[server]),
+            patch('app.services.pricing_engine.get_user_active_promo_discount_percent', return_value=0),
+            patch('app.services.pricing_engine.settings') as ms,
+            patch('app.services.pricing_engine.CLASSIC_PERIOD_PRICES', {90: 27000}),
+            patch('app.services.pricing_engine.PERIOD_PRICES', {}),
+        ):
+            ms.DEFAULT_DEVICE_LIMIT = 1
+            ms.PRICE_PER_DEVICE = 5000
+            ms.get_traffic_price.return_value = 2000
+            ms.is_traffic_fixed.return_value = False
+            ms.DEFAULT_TRAFFIC_LIMIT_GB = 50
+
+            result = await engine.calculate_renewal_price(db, sub, 90, user=user)
+
+        assert result.period_days == 90
+        assert result.base_price == 27000
+        # Servers and traffic are monthly x 3 months
+        assert result.servers_price == 3000 * 3
+        assert result.traffic_price == 2000 * 3
+        assert result.devices_price == 0  # no extra devices
+        assert result.final_total == 27000 + 9000 + 6000
+
+    @pytest.mark.asyncio
+    async def test_classic_per_category_different_discounts(self):
+        """Different discount percents per category (period=10%, servers=20%, traffic=30%, devices=0%)."""
+        engine = PricingEngine()
+        db = AsyncMock()
+        sub = MagicMock()
+        sub.tariff_id = None
+        sub.tariff = None
+        sub.connected_squads = ['uuid-s1']
+        sub.traffic_limit_gb = 100
+        sub.purchased_traffic_gb = 0
+        sub.device_limit = 3  # 2 extra devices
+
+        user = MagicMock()
+        promo_group = MagicMock()
+
+        def discount_by_category(category, period_days):
+            return {'period': 10, 'servers': 20, 'traffic': 30, 'devices': 0}[category]
+
+        promo_group.get_discount_percent = MagicMock(side_effect=discount_by_category)
+        user.promo_group = promo_group
+        user.promo_group_id = 1
+
+        server = _make_server(price_kopeks=6000, squad_uuid='uuid-s1')
+
+        with (
+            patch('app.services.pricing_engine.get_server_squads_by_uuids', return_value=[server]),
+            patch('app.services.pricing_engine.get_user_active_promo_discount_percent', return_value=0),
+            patch('app.services.pricing_engine.settings') as ms,
+            patch('app.services.pricing_engine.CLASSIC_PERIOD_PRICES', {30: 10000}),
+            patch('app.services.pricing_engine.PERIOD_PRICES', {}),
+        ):
+            ms.DEFAULT_DEVICE_LIMIT = 1
+            ms.PRICE_PER_DEVICE = 4000
+            ms.get_traffic_price.return_value = 5000
+            ms.is_traffic_fixed.return_value = False
+            ms.DEFAULT_TRAFFIC_LIMIT_GB = 100
+
+            result = await engine.calculate_renewal_price(db, sub, 30, user=user)
+
+        # period: 10000 * 10% = 1000 discount -> 9000
+        assert result.base_price == 9000
+        # servers: 6000 * 20% = 1200 discount -> 4800 per month x 1
+        assert result.servers_price == 4800
+        # traffic: 5000 * 30% = 1500 discount -> 3500 per month x 1
+        assert result.traffic_price == 3500
+        # devices: 2 extra x 4000 = 8000, 0% discount -> 8000
+        assert result.devices_price == 8000
+        # total group discount = 1000 + 1200 + 1500 + 0 = 3700
+        assert result.promo_group_discount == 3700
+        assert result.final_total == 9000 + 4800 + 3500 + 8000
+
+
+class TestServerPromoGroupFiltering:
+    @pytest.mark.asyncio
+    async def test_server_not_allowed_for_promo_group(self):
+        """Server with restricted promo groups still charges real price."""
+        engine = PricingEngine()
+        db = AsyncMock()
+        pg_mock = MagicMock()
+        pg_mock.id = 99
+        server = _make_server(price_kopeks=5000, squad_uuid='uuid-1', allowed_promo_groups=[pg_mock])
+        with patch('app.services.pricing_engine.get_server_squads_by_uuids', return_value=[server]):
+            total, details = await engine._calculate_servers_price(['uuid-1'], db, promo_group_id=5)
+        assert total == 5000  # real price still charged
+        assert details[0]['status'] == 'not_allowed'
+
+    @pytest.mark.asyncio
+    async def test_server_empty_allowed_groups_is_open(self):
+        """Server with empty allowed_promo_groups is available to all."""
+        engine = PricingEngine()
+        db = AsyncMock()
+        server = _make_server(price_kopeks=5000, squad_uuid='uuid-1', allowed_promo_groups=[])
+        with patch('app.services.pricing_engine.get_server_squads_by_uuids', return_value=[server]):
+            total, details = await engine._calculate_servers_price(['uuid-1'], db, promo_group_id=5)
+        assert total == 5000
+        assert details[0]['status'] == 'available'
+
+
+class TestFromPayloadRoundTrip:
+    def test_renewal_pricing_snapshot_roundtrip(self):
+        """RenewalPricing serialized via asdict() is correctly restored by from_payload()."""
+        import dataclasses
+
+        from app.services.subscription_renewal_service import SubscriptionRenewalPricing
+
+        pricing = RenewalPricing(
+            base_price=29000,
+            servers_price=5000,
+            traffic_price=3000,
+            devices_price=0,
+            promo_group_discount=2000,
+            promo_offer_discount=800,
+            final_total=34200,
+            period_days=30,
+            is_tariff_mode=False,
+            breakdown={
+                'server_ids': [1, 2],
+                'servers_individual_prices': [5000, 3000],
+                'offer_discount_pct': 5,
+            },
+        )
+        payload = dataclasses.asdict(pricing)
+        restored = SubscriptionRenewalPricing.from_payload(payload)
+
+        assert restored.final_total == 34200
+        assert restored.period_days == 30
+        assert restored.promo_discount_value == 800  # mapped from promo_offer_discount
+        assert restored.server_ids == [1, 2]
+        assert restored.details.get('servers_individual_prices') == [5000, 3000]
+        assert restored.months == 1
+        assert restored.per_month == 34200
+
+
+# ---------------------------------------------------------------------------
+# Patch-target constants used in new tests below
+# ---------------------------------------------------------------------------
+SERVERS_BATCH_PATH = 'app.services.pricing_engine.get_server_squads_by_uuids'
+SETTINGS_PATH = 'app.services.pricing_engine.settings'
+
+
+class TestFromPayloadLegacyRoundTrip:
+    def test_legacy_to_payload_roundtrip(self):
+        """Legacy SubscriptionRenewalPricing.to_payload() -> from_payload() preserves all fields."""
+        from app.services.subscription_renewal_service import SubscriptionRenewalPricing, build_renewal_period_id
+
+        original = SubscriptionRenewalPricing(
+            period_days=30,
+            period_id=build_renewal_period_id(30),
+            months=1,
+            base_original_total=15000,
+            discounted_total=12000,
+            final_total=10800,
+            promo_discount_value=1200,
+            promo_discount_percent=10,
+            overall_discount_percent=28,
+            per_month=10800,
+            server_ids=[1, 2, 3],
+            details={'servers_individual_prices': [5000, 3000, 2000]},
+        )
+        payload = original.to_payload()
+        restored = SubscriptionRenewalPricing.from_payload(payload)
+
+        assert restored.period_days == original.period_days
+        assert restored.period_id == original.period_id
+        assert restored.months == original.months
+        assert restored.base_original_total == original.base_original_total
+        assert restored.discounted_total == original.discounted_total
+        assert restored.final_total == original.final_total
+        assert restored.promo_discount_value == original.promo_discount_value
+        assert restored.promo_discount_percent == original.promo_discount_percent
+        assert restored.overall_discount_percent == original.overall_discount_percent
+        assert restored.per_month == original.per_month
+        assert restored.server_ids == original.server_ids
+
+
+class TestOriginalPriceIdentity:
+    @pytest.mark.asyncio
+    async def test_tariff_mode_identity(self):
+        """final_total + promo_group_discount + promo_offer_discount == undiscounted subtotal."""
+        engine = PricingEngine()
+        db = AsyncMock()
+        tariff = MagicMock()
+        tariff.id = 1
+        tariff.period_prices = {'30': 20000}
+        tariff.device_price_kopeks = 3000
+        tariff.device_limit = 1
+        sub = MagicMock()
+        sub.tariff_id = 1
+        sub.tariff = tariff
+        sub.device_limit = 3  # 2 extra
+        user = MagicMock()
+        promo_group = MagicMock()
+        promo_group.get_discount_percent = MagicMock(return_value=25)
+        user.promo_group = promo_group
+
+        with patch('app.services.pricing_engine.get_user_active_promo_discount_percent', return_value=15):
+            result = await engine.calculate_renewal_price(db, sub, 30, user=user)
+
+        subtotal = 20000 + 2 * 3000  # 26000
+        assert result.final_total + result.promo_group_discount + result.promo_offer_discount == subtotal
+
+    @pytest.mark.asyncio
+    async def test_classic_mode_identity(self):
+        """final_total + promo_group_discount + promo_offer_discount == undiscounted total in classic mode."""
+        engine = PricingEngine()
+        db = AsyncMock()
+        sub = MagicMock()
+        sub.tariff_id = None
+        sub.tariff = None
+        sub.connected_squads = ['uuid-s1']
+        sub.traffic_limit_gb = 50
+        sub.purchased_traffic_gb = 0
+        sub.device_limit = 2  # 1 extra
+
+        user = MagicMock()
+        promo_group = MagicMock()
+        promo_group.get_discount_percent = MagicMock(return_value=20)
+        user.promo_group = promo_group
+        user.promo_group_id = 1
+
+        server = _make_server(price_kopeks=4000, squad_uuid='uuid-s1')
+
+        with (
+            patch(SERVERS_BATCH_PATH, return_value=[server]),
+            patch('app.services.pricing_engine.get_user_active_promo_discount_percent', return_value=10),
+            patch(SETTINGS_PATH) as ms,
+            patch('app.services.pricing_engine.CLASSIC_PERIOD_PRICES', {30: 10000}),
+            patch('app.services.pricing_engine.PERIOD_PRICES', {}),
+        ):
+            ms.PRICE_PER_DEVICE = 5000
+            ms.DEFAULT_DEVICE_LIMIT = 1
+            ms.get_traffic_price.return_value = 3000
+            ms.is_traffic_fixed.return_value = False
+            ms.DEFAULT_TRAFFIC_LIMIT_GB = 50
+
+            result = await engine.calculate_renewal_price(db, sub, 30, user=user)
+
+        # Reconstruct original undiscounted total
+        original = result.final_total + result.promo_group_discount + result.promo_offer_discount
+        # original should equal base_original + servers_original + traffic_original + devices_original
+        expected_original = 10000 + 4000 + 3000 + 5000  # 22000
+        assert original == expected_original