feat(domains): support username root domain claims

domain_manager.py

@@ -463,7 +463,7 @@ class DomainManager:
         """
         try:
             # Validate inputs
-            if not username or not subdomain_name:
+            if not username or subdomain_name is None:
                 return {
                     'success': False,
                     'message': "Username and subdomain name are required",
@@ -478,7 +478,7 @@ class DomainManager:
                 return {'success': False, 'message': "Username cannot be represented as a DNS name", 'domain_data': None}
 
             # Hostnames are single labels below u-<username>.
-            if not self._is_valid_subdomain(subdomain_name):
+            if subdomain_name and not self._is_valid_subdomain(subdomain_name):
                 return {
                     'success': False,
                     'message': "Invalid subdomain name. Use only letters, numbers, and hyphens",
@@ -487,7 +487,7 @@ class DomainManager:
 
             # Construct domains
             user_domain = f"u-{username}.{self.base_domain}"
-            full_subdomain = f"{subdomain_name}.{user_domain}"
+            full_subdomain = f"{subdomain_name}.{user_domain}" if subdomain_name else user_domain
             namespace = self.ensure_user_namespace(username)
             if not namespace['success']:
                 return {'success': False, 'message': namespace['message'], 'domain_data': None}
@@ -631,7 +631,7 @@ class DomainManager:
     def delete_subdomain(self, username: str, subdomain_name: str) -> Dict:
         """Delete a subdomain"""
         try:
-            if not username or not subdomain_name:
+            if not username or subdomain_name is None:
                 return {
                     'success': False,
                     'message': "Username and subdomain name are required"
@@ -639,9 +639,14 @@ class DomainManager:
 
             username = username.lower().strip()
             subdomain_name = subdomain_name.lower().strip()
-            if not self._is_valid_username_label(username) or not self._is_valid_subdomain(subdomain_name):
+            if not self._is_valid_username_label(username):
                 return {'success': False, 'message': "Invalid username or subdomain"}
             user_domain = f"u-{username}.{self.base_domain}"
+            # Releasing the optional root claim must never remove the shared namespace DNS.
+            if not subdomain_name:
+                return {'success': True, 'message': f"Domain claim {user_domain} deleted"}
+            if not self._is_valid_subdomain(subdomain_name):
+                return {'success': False, 'message': "Invalid username or subdomain"}
             full_subdomain = f"{subdomain_name}.{user_domain}"
 
             # New namespaces use a shared wildcard in the parent zone. Do not
@@ -848,7 +853,7 @@ class DomainManager:
             subdomain_name = subdomain_name.lower().strip()
 
             # First validate the subdomain name
-            if not self._is_valid_subdomain(subdomain_name):
+            if subdomain_name and not self._is_valid_subdomain(subdomain_name):
                 return {
                     'available': False,
                     'message': f"Invalid subdomain name: {subdomain_name}"