diff --git a/cloud_backend/routers/heartbeat.py b/cloud_backend/routers/heartbeat.py
index eeef21b..5f84e90 100644
--- a/cloud_backend/routers/heartbeat.py
+++ b/cloud_backend/routers/heartbeat.py
@@ -39,4 +39,5 @@ def heartbeat(
         expires_at=site.license_expires_at,
         latest_version=settings.LATEST_VERSION,
         waiter_domain=site.waiter_domain,
+        site_numeric_id=site.id,
     )
diff --git a/cloud_backend/schemas/site.py b/cloud_backend/schemas/site.py
index 257f92b..0ede54c 100644
--- a/cloud_backend/schemas/site.py
+++ b/cloud_backend/schemas/site.py
@@ -57,3 +57,4 @@ class HeartbeatResponse(BaseModel):
     expires_at: datetime
     latest_version: str | None = None
     waiter_domain: str | None = None
+    site_numeric_id: int | None = None  # cloud DB pk — needed by Connect sync loops