Complete Implemenation of tenancy

backend/igny8_core/business/billing/models.py

@@ -201,9 +201,6 @@ class Invoice(AccountBaseModel):
     # Payment integration
     stripe_invoice_id = models.CharField(max_length=255, null=True, blank=True)
     payment_method = models.CharField(max_length=50, null=True, blank=True)
-    billing_email = models.EmailField(null=True, blank=True)
-    billing_period_start = models.DateTimeField(null=True, blank=True)
-    billing_period_end = models.DateTimeField(null=True, blank=True)
     
     # Metadata
     notes = models.TextField(blank=True)
@@ -240,6 +237,23 @@ class Invoice(AccountBaseModel):
     def total_amount(self):
         return self.total
 
+    @property
+    def billing_period_start(self):
+        """Get from subscription - single source of truth"""
+        return self.subscription.current_period_start if self.subscription else None
+    
+    @property
+    def billing_period_end(self):
+        """Get from subscription - single source of truth"""
+        return self.subscription.current_period_end if self.subscription else None
+    
+    @property
+    def billing_email(self):
+        """Get from metadata snapshot or account"""
+        if self.metadata and 'billing_snapshot' in self.metadata:
+            return self.metadata['billing_snapshot'].get('email')
+        return self.account.billing_email if self.account else None
+
     def add_line_item(self, description: str, quantity: int, unit_price: Decimal, amount: Decimal = None):
         """Append a line item and keep JSON shape consistent."""
         items = list(self.line_items or [])
@@ -316,7 +330,6 @@ class Payment(AccountBaseModel):
         help_text="Bank transfer reference, wallet transaction ID, etc."
     )
     manual_notes = models.TextField(blank=True, help_text="Admin notes for manual payments")
-    transaction_reference = models.CharField(max_length=255, blank=True)
     admin_notes = models.TextField(blank=True, help_text="Internal notes on approval/rejection")
     approved_by = models.ForeignKey(
         settings.AUTH_USER_MODEL,