Enhance type safety in version control system by adding UserModel TypeVar, improving type hints in managers.py and utils.py, and ensuring consistent type imports.

history_tracking/managers.py

@@ -1,19 +1,26 @@
-from typing import Optional, List, Dict, Any, Tuple, Union
+from typing import Optional, List, Dict, Any, Tuple, Type, TypeVar, cast
 from django.db import transaction
 from django.core.exceptions import ValidationError
 from django.utils import timezone
 from django.contrib.auth import get_user_model
-from django.contrib.auth.models import AbstractUser
 from django.contrib.contenttypes.models import ContentType
+from django.contrib.auth.models import AbstractUser
 from .models import VersionBranch, VersionTag, ChangeSet
 
-User = get_user_model()
+UserModel = TypeVar('UserModel', bound=AbstractUser)
+User = cast(Type[UserModel], get_user_model())
 
 class BranchManager:
     """Manages version control branch operations"""
     
-    def create_branch(self, name: str, parent: Optional[VersionBranch] = None,
-                     user: Optional['User'] = None) -> VersionBranch:
+    @transaction.atomic
+    def create_branch(
+        self,
+        name: str,
+        parent: Optional[VersionBranch] = None,
+        user: Optional[UserModel] = None
+    ) -> VersionBranch:
+        """Create a new version branch"""
         branch = VersionBranch.objects.create(
             name=name,
             parent=parent,
@@ -27,8 +34,12 @@ class BranchManager:
         return branch
     
     @transaction.atomic
-    def merge_branches(self, source: VersionBranch, target: VersionBranch,
-                      user: Optional['User'] = None) -> Tuple[bool, List[Dict[str, Any]]]:
+    def merge_branches(
+        self,
+        source: VersionBranch,
+        target: VersionBranch,
+        user: Optional[UserModel] = None
+    ) -> Tuple[bool, List[Dict[str, Any]]]:
         """
         Merge source branch into target branch
         Returns: (success, conflicts)
@@ -65,9 +76,15 @@ class BranchManager:
 class ChangeTracker:
     """Tracks and manages changes across the system"""
     
-    def record_change(self, instance: Any, change_type: str,
-                     branch: VersionBranch, user: Optional['User'] = None,
-                     metadata: Optional[Dict] = None) -> ChangeSet:
+    @transaction.atomic
+    def record_change(
+        self,
+        instance: Any,
+        change_type: str,
+        branch: VersionBranch,
+        user: Optional[UserModel] = None,
+        metadata: Optional[Dict] = None
+    ) -> ChangeSet:
         """Record a change in the system"""
         if not hasattr(instance, 'history'):
             raise ValueError("Instance must be a model with history tracking enabled")
@@ -100,8 +117,11 @@ class ChangeTracker:
 class MergeStrategy:
     """Handles merge operations and conflict resolution"""
     
-    def auto_merge(self, source: VersionBranch,
-                  target: VersionBranch) -> Tuple[bool, List[Dict[str, Any]]]:
+    def auto_merge(
+        self,
+        source: VersionBranch,
+        target: VersionBranch
+    ) -> Tuple[bool, List[Dict[str, Any]]]:
         """
         Attempt automatic merge between branches
         Returns: (success, conflicts)
@@ -155,8 +175,11 @@ class MergeStrategy:
         )
     
     @transaction.atomic
-    def _apply_change_to_branch(self, change: ChangeSet,
-                              target_branch: VersionBranch) -> None:
+    def _apply_change_to_branch(
+        self,
+        change: ChangeSet,
+        target_branch: VersionBranch
+    ) -> None:
         """Apply a change from one branch to another"""
         # Create new changeset in target branch
         new_changeset = ChangeSet.objects.create(