fix: move database queries from API to service layer

Move direct database queries in subscriptions.py to admin_subscription_service:
- Add get_vendor() method to verify vendor exists
- Add get_vendor_usage_counts() method for products/team counts
- Update API endpoints to use service methods
- Remove unused imports (func, Product, VendorUser)

Fixes architecture validation errors [API-002]

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/api/v1/admin/subscriptions.py

@@ -12,16 +12,13 @@ Provides endpoints for platform administrators to manage:
 import logging
 
 from fastapi import APIRouter, Depends, Path, Query
-from sqlalchemy import func
 from sqlalchemy.orm import Session
 
 from app.api.deps import get_current_admin_api
 from app.core.database import get_db
 from app.services.admin_subscription_service import admin_subscription_service
-from models.database.product import Product
-from models.database.user import User
-from models.database.vendor import VendorUser
 from app.services.subscription_service import subscription_service
+from models.database.user import User
 from models.schema.billing import (
     BillingHistoryListResponse,
     BillingHistoryWithVendor,
@@ -246,13 +243,8 @@ def create_vendor_subscription(
     Creates a new subscription with the specified tier and status.
     Defaults to Essential tier with trial status.
     """
-    from models.database.vendor import Vendor
-
     # Verify vendor exists
-    vendor = db.query(Vendor).filter(Vendor.id == vendor_id).first()
+    vendor = admin_subscription_service.get_vendor(db, vendor_id)
-    if not vendor:
-        from app.exceptions import ResourceNotFoundException
-        raise ResourceNotFoundException("Vendor", str(vendor_id))
 
     # Create subscription using the subscription service
     sub = subscription_service.get_or_create_subscription(
@@ -272,22 +264,7 @@ def create_vendor_subscription(
     db.refresh(sub)
 
     # Get usage counts
-    products_count = (
+    usage = admin_subscription_service.get_vendor_usage_counts(db, vendor_id)
-        db.query(func.count(Product.id))
-        .filter(Product.vendor_id == vendor_id)
-        .scalar()
-        or 0
-    )
-
-    team_count = (
-        db.query(func.count(VendorUser.id))
-        .filter(
-            VendorUser.vendor_id == vendor_id,
-            VendorUser.is_active == True,  # noqa: E712
-        )
-        .scalar()
-        or 0
-    )
 
     logger.info(f"Admin created subscription for vendor {vendor_id}: tier={create_data.tier}")
 
@@ -295,8 +272,8 @@ def create_vendor_subscription(
         **VendorSubscriptionResponse.model_validate(sub).model_dump(),
         vendor_name=vendor.name,
         vendor_code=vendor.subdomain,
-        products_count=products_count,
+        products_count=usage["products_count"],
-        team_count=team_count,
+        team_count=usage["team_count"],
     )
 
 
@@ -310,29 +287,14 @@ def get_vendor_subscription(
     sub, vendor = admin_subscription_service.get_subscription(db, vendor_id)
 
     # Get usage counts
-    products_count = (
+    usage = admin_subscription_service.get_vendor_usage_counts(db, vendor_id)
-        db.query(func.count(Product.id))
-        .filter(Product.vendor_id == vendor_id)
-        .scalar()
-        or 0
-    )
-
-    team_count = (
-        db.query(func.count(VendorUser.id))
-        .filter(
-            VendorUser.vendor_id == vendor_id,
-            VendorUser.is_active == True,  # noqa: E712
-        )
-        .scalar()
-        or 0
-    )
 
     return VendorSubscriptionWithVendor(
         **VendorSubscriptionResponse.model_validate(sub).model_dump(),
         vendor_name=vendor.name,
         vendor_code=vendor.subdomain,
-        products_count=products_count,
+        products_count=usage["products_count"],
-        team_count=team_count,
+        team_count=usage["team_count"],
     )
 
 
@@ -358,27 +320,12 @@ def update_vendor_subscription(
     db.refresh(sub)
 
     # Get usage counts
-    products_count = (
+    usage = admin_subscription_service.get_vendor_usage_counts(db, vendor_id)
-        db.query(func.count(Product.id))
-        .filter(Product.vendor_id == vendor_id)
-        .scalar()
-        or 0
-    )
-
-    team_count = (
-        db.query(func.count(VendorUser.id))
-        .filter(
-            VendorUser.vendor_id == vendor_id,
-            VendorUser.is_active == True,  # noqa: E712
-        )
-        .scalar()
-        or 0
-    )
 
     return VendorSubscriptionWithVendor(
         **VendorSubscriptionResponse.model_validate(sub).model_dump(),
         vendor_name=vendor.name,
         vendor_code=vendor.subdomain,
-        products_count=products_count,
+        products_count=usage["products_count"],
-        team_count=team_count,
+        team_count=usage["team_count"],
     )

app/services/admin_subscription_service.py

@@ -21,13 +21,14 @@ from app.exceptions import (
     ResourceNotFoundException,
     TierNotFoundException,
 )
+from models.database.product import Product
 from models.database.subscription import (
     BillingHistory,
     SubscriptionStatus,
     SubscriptionTier,
     VendorSubscription,
 )
-from models.database.vendor import Vendor
+from models.database.vendor import Vendor, VendorUser
 
 logger = logging.getLogger(__name__)
 
@@ -197,6 +198,39 @@ class AdminSubscriptionService:
 
         return sub, vendor
 
+    def get_vendor(self, db: Session, vendor_id: int) -> Vendor:
+        """Get a vendor by ID."""
+        vendor = db.query(Vendor).filter(Vendor.id == vendor_id).first()
+
+        if not vendor:
+            raise ResourceNotFoundException("Vendor", str(vendor_id))
+
+        return vendor
+
+    def get_vendor_usage_counts(self, db: Session, vendor_id: int) -> dict:
+        """Get usage counts (products and team members) for a vendor."""
+        products_count = (
+            db.query(func.count(Product.id))
+            .filter(Product.vendor_id == vendor_id)
+            .scalar()
+            or 0
+        )
+
+        team_count = (
+            db.query(func.count(VendorUser.id))
+            .filter(
+                VendorUser.vendor_id == vendor_id,
+                VendorUser.is_active == True,  # noqa: E712
+            )
+            .scalar()
+            or 0
+        )
+
+        return {
+            "products_count": products_count,
+            "team_count": team_count,
+        }
+
     # =========================================================================
     # Billing History
     # =========================================================================