diff --git a/tests/test_build_services_wiring.py b/tests/test_build_services_wiring.py
new file mode 100644
index 0000000..3e194c6
--- /dev/null
+++ b/tests/test_build_services_wiring.py
@@ -0,0 +1,139 @@
+"""Pins the cross-service wiring that ``build_core_services`` performs.
+
+Two non-obvious attachments are critical and have already been the cause of
+silent regressions:
+
+* ``subscription_service.yookassa_service`` powers auto-renew. Without it the
+  charge step logs ``YooKassa unavailable for auto-renew`` and gives up.
+* ``panel_webhook_service.subscription_service`` lets the 24h-before-expiry
+  panel webhook trigger an auto-renew through the subscription service.
+
+These tests catch any future regression that drops either attachment, or
+silently swallows the wiring step.
+"""
+
+import json
+import tempfile
+import unittest
+from pathlib import Path
+from typing import Any
+from unittest.mock import MagicMock
+
+from bot.app.factories.build_services import build_core_services
+from bot.services.panel_webhook_service import PanelWebhookService
+from bot.services.subscription_service import SubscriptionService
+from bot.services.yookassa_service import YooKassaService
+from config.settings import Settings
+
+
+def _make_settings(tmpdir: str, **overrides: Any) -> Settings:
+    config_path = Path(tmpdir) / "tariffs.json"
+    config_path.write_text(
+        json.dumps(
+            {
+                "default_tariff": "standard",
+                "tariffs": [
+                    {
+                        "key": "standard",
+                        "names": {"en": "Standard"},
+                        "descriptions": {"en": "Base"},
+                        "squad_uuids": ["main"],
+                        "billing_model": "period",
+                        "monthly_gb": 100,
+                        "prices_rub": {"1": 100},
+                        "prices_stars": {"1": 0},
+                        "enabled_periods": [1],
+                        "enabled": True,
+                    }
+                ],
+            }
+        ),
+        encoding="utf-8",
+    )
+    values: dict[str, Any] = {
+        "_env_file": None,
+        "BOT_TOKEN": "token",
+        "POSTGRES_USER": "u",
+        "POSTGRES_PASSWORD": "p",
+        "TARIFFS_CONFIG_PATH": str(config_path),
+    }
+    values.update(overrides)
+    return Settings(**values)
+
+
+class BuildServicesWiringTests(unittest.TestCase):
+    def test_subscription_service_receives_yookassa_handle(self):
+        """Auto-renew reads ``self.yookassa_service`` directly. If this
+        attachment ever disappears, every YooKassa auto-renew will silently
+        return False without anyone noticing until a charge is missed."""
+        with tempfile.TemporaryDirectory() as tmpdir:
+            settings = _make_settings(tmpdir)
+            services = build_core_services(
+                settings=settings,
+                bot=MagicMock(),
+                async_session_factory=MagicMock(),
+                i18n=MagicMock(),
+                bot_username_for_default_return="testbot",
+            )
+
+        subscription = services["subscription_service"]
+        yookassa = services["yookassa_service"]
+        self.assertIsInstance(subscription, SubscriptionService)
+        self.assertIsInstance(yookassa, YooKassaService)
+        # Identity check: the wired attribute must be the *same* instance.
+        self.assertIs(getattr(subscription, "yookassa_service", None), yookassa)
+
+    def test_panel_webhook_service_can_reach_subscription_service(self):
+        """The 24h pre-expiry handler in panel_webhook_service.handle_event
+        calls ``getattr(self, 'subscription_service', None)`` and skips the
+        auto-renew nudge if it returns None. Pin the back-reference."""
+        with tempfile.TemporaryDirectory() as tmpdir:
+            settings = _make_settings(tmpdir)
+            services = build_core_services(
+                settings=settings,
+                bot=MagicMock(),
+                async_session_factory=MagicMock(),
+                i18n=MagicMock(),
+                bot_username_for_default_return="testbot",
+            )
+
+        panel_webhook = services["panel_webhook_service"]
+        subscription = services["subscription_service"]
+        self.assertIsInstance(panel_webhook, PanelWebhookService)
+        self.assertIs(
+            getattr(panel_webhook, "subscription_service", None), subscription
+        )
+
+    def test_factory_returns_every_documented_service(self):
+        """Guards against silently dropping a service from the bundle. The
+        web layer reads these keys off ``request.app`` directly — a missing
+        key turns into a runtime KeyError at request time."""
+        with tempfile.TemporaryDirectory() as tmpdir:
+            settings = _make_settings(tmpdir)
+            services = build_core_services(
+                settings=settings,
+                bot=MagicMock(),
+                async_session_factory=MagicMock(),
+                i18n=MagicMock(),
+                bot_username_for_default_return="testbot",
+            )
+
+        expected_keys = {
+            "panel_service",
+            "subscription_service",
+            "referral_service",
+            "promo_code_service",
+            "stars_service",
+            "cryptopay_service",
+            "freekassa_service",
+            "panel_webhook_service",
+            "yookassa_service",
+            "lknpd_service",
+            "platega_service",
+            "severpay_service",
+        }
+        self.assertEqual(set(services), expected_keys)
+
+
+if __name__ == "__main__":  # pragma: no cover
+    unittest.main()