Add comment and reply functionality with preview and notification templates

history_tracking/comparison.py

@@ -0,0 +1,237 @@
+import asyncio
+import json
+from typing import List, Dict, Any, Optional
+from django.core.cache import cache
+from django.db import models
+from django.utils import timezone
+from concurrent.futures import ThreadPoolExecutor
+from .models import VersionTag, ChangeSet
+
+class StructuredDiff:
+    def __init__(self, version1: str, version2: str):
+        self.version1 = version1
+        self.version2 = version2
+        self.changes: List[Dict[str, Any]] = []
+        self.impact_score = 0.0
+        self.computation_time = 0.0
+        self.timestamp = timezone.now()
+
+    def to_dict(self) -> Dict[str, Any]:
+        return {
+            'version1': self.version1,
+            'version2': self.version2,
+            'changes': self.changes,
+            'impact_score': self.impact_score,
+            'computation_time': self.computation_time,
+            'timestamp': self.timestamp.isoformat()
+        }
+
+    @classmethod
+    def from_dict(cls, data: Dict[str, Any]) -> 'StructuredDiff':
+        diff = cls(data['version1'], data['version2'])
+        diff.changes = data['changes']
+        diff.impact_score = data['impact_score']
+        diff.computation_time = data['computation_time']
+        diff.timestamp = timezone.datetime.fromisoformat(data['timestamp'])
+        return diff
+
+class ComparisonEngine:
+    """Handles version comparison operations with background processing and caching"""
+
+    def __init__(self, chunk_size: int = 10485760):  # 10MB default chunk size
+        self.chunk_size = chunk_size
+        self.executor = ThreadPoolExecutor(max_workers=4)
+        self.cache_ttl = 300  # 5 minutes cache TTL
+
+    async def compare_versions(self, versions: List[str]) -> List[StructuredDiff]:
+        """
+        Compare multiple versions, processing in background and using cache
+        Args:
+            versions: List of version identifiers to compare
+        Returns:
+            List of StructuredDiff objects with comparison results
+        """
+        if len(versions) < 2:
+            raise ValueError("At least two versions required for comparison")
+
+        results: List[StructuredDiff] = []
+        cache_misses = []
+
+        # Check cache first
+        for i in range(len(versions) - 1):
+            for j in range(i + 1, len(versions)):
+                cache_key = self._get_cache_key(versions[i], versions[j])
+                cached_result = cache.get(cache_key)
+                
+                if cached_result:
+                    results.append(StructuredDiff.from_dict(json.loads(cached_result)))
+                else:
+                    cache_misses.append((versions[i], versions[j]))
+
+        # Process cache misses in background
+        if cache_misses:
+            comparison_tasks = [
+                self._compare_version_pair(v1, v2)
+                for v1, v2 in cache_misses
+            ]
+            new_results = await asyncio.gather(*comparison_tasks)
+            results.extend(new_results)
+
+        return sorted(
+            results,
+            key=lambda x: (x.version1, x.version2)
+        )
+
+    def calculate_impact_score(self, diffs: List[StructuredDiff]) -> float:
+        """
+        Calculate impact score for a set of diffs
+        Args:
+            diffs: List of StructuredDiff objects
+        Returns:
+            Float impact score (0-1)
+        """
+        if not diffs:
+            return 0.0
+
+        total_score = 0.0
+        weights = {
+            'file_count': 0.3,
+            'change_size': 0.3,
+            'structural_impact': 0.4
+        }
+
+        for diff in diffs:
+            # File count impact
+            file_count = len(set(c['file'] for c in diff.changes))
+            file_score = min(file_count / 100, 1.0)  # Normalize to max 100 files
+
+            # Change size impact
+            total_changes = sum(
+                len(c.get('additions', [])) + len(c.get('deletions', []))
+                for c in diff.changes
+            )
+            size_score = min(total_changes / 1000, 1.0)  # Normalize to max 1000 lines
+
+            # Structural impact (e.g., function/class changes)
+            structural_changes = sum(
+                1 for c in diff.changes
+                if c.get('type') in ['function', 'class', 'schema']
+            )
+            structural_score = min(structural_changes / 10, 1.0)  # Normalize to max 10 structural changes
+
+            # Weighted average
+            diff.impact_score = (
+                weights['file_count'] * file_score +
+                weights['change_size'] * size_score +
+                weights['structural_impact'] * structural_score
+            )
+            total_score += diff.impact_score
+
+        return total_score / len(diffs)
+
+    async def _compare_version_pair(self, version1: str, version2: str) -> StructuredDiff:
+        """Compare two versions in background"""
+        start_time = timezone.now()
+        
+        # Create diff structure
+        diff = StructuredDiff(version1, version2)
+        
+        try:
+            # Get version data
+            v1_tag = await self._get_version_tag(version1)
+            v2_tag = await self._get_version_tag(version2)
+            
+            if not v1_tag or not v2_tag:
+                raise ValueError("Version tag not found")
+
+            # Process in chunks if needed
+            changes = await self._process_version_changes(v1_tag, v2_tag)
+            diff.changes = changes
+            
+            # Calculate impact score
+            diff.impact_score = self.calculate_impact_score([diff])
+            
+            # Store in cache
+            cache_key = self._get_cache_key(version1, version2)
+            cache.set(
+                cache_key,
+                json.dumps(diff.to_dict()),
+                self.cache_ttl
+            )
+            
+        except Exception as e:
+            diff.changes = [{'error': str(e)}]
+            diff.impact_score = 0.0
+        
+        diff.computation_time = (timezone.now() - start_time).total_seconds()
+        return diff
+
+    async def _get_version_tag(self, version: str) -> Optional[VersionTag]:
+        """Get version tag by identifier"""
+        loop = asyncio.get_event_loop()
+        return await loop.run_in_executor(
+            self.executor,
+            lambda: VersionTag.objects.filter(name=version).first()
+        )
+
+    async def _process_version_changes(
+        self,
+        v1_tag: VersionTag,
+        v2_tag: VersionTag
+    ) -> List[Dict[str, Any]]:
+        """Process changes between versions in chunks"""
+        changes = []
+        
+        # Get changesets between versions
+        changesets = await self._get_changesets_between(v1_tag, v2_tag)
+        
+        for changeset in changesets:
+            # Process each change in chunks if needed
+            change_data = await self._process_changeset(changeset)
+            changes.extend(change_data)
+        
+        return changes
+
+    async def _get_changesets_between(
+        self,
+        v1_tag: VersionTag,
+        v2_tag: VersionTag
+    ) -> List[ChangeSet]:
+        """Get all changesets between two versions"""
+        loop = asyncio.get_event_loop()
+        return await loop.run_in_executor(
+            self.executor,
+            lambda: list(ChangeSet.objects.filter(
+                branch=v2_tag.branch,
+                created_at__gt=v1_tag.created_at,
+                created_at__lte=v2_tag.created_at,
+                status='applied'
+            ).order_by('created_at'))
+        )
+
+    async def _process_changeset(self, changeset: ChangeSet) -> List[Dict[str, Any]]:
+        """Process individual changeset for comparison"""
+        loop = asyncio.get_event_loop()
+        
+        def process():
+            changes = []
+            instance = changeset.historical_instance
+            if instance:
+                # Get changes from historical record
+                diff = instance.diff_against_previous
+                if diff:
+                    for field, values in diff.items():
+                        change = {
+                            'type': 'field',
+                            'file': f"{instance._meta.model_name}.{field}",
+                            'old_value': values['old'],
+                            'new_value': values['new']
+                        }
+                        changes.append(change)
+            return changes
+        
+        return await loop.run_in_executor(self.executor, process)
+
+    def _get_cache_key(self, version1: str, version2: str) -> str:
+        """Generate cache key for version comparison"""
+        return f"version_diff:{version1}:{version2}"

history_tracking/htmx_views.py

@@ -0,0 +1,123 @@
+from django.shortcuts import render, get_object_or_404
+from django.contrib.auth.decorators import login_required
+from django.views.decorators.http import require_http_methods
+from django.http import HttpRequest, HttpResponse, Http404
+from django.template.loader import render_to_string
+from django.core.exceptions import PermissionDenied
+
+from .models import ChangeSet, CommentThread, Comment
+from .notifications import NotificationDispatcher
+from .state_machine import ApprovalStateMachine
+
+@login_required
+def get_comments(request: HttpRequest) -> HttpResponse:
+    """HTMX endpoint to get comments for a specific anchor"""
+    anchor = request.GET.get('anchor')
+    if not anchor:
+        raise Http404("Anchor parameter is required")
+
+    thread = CommentThread.objects.filter(anchor__id=anchor).first()
+    comments = thread.comments.all() if thread else []
+
+    return render(request, 'history_tracking/partials/comments_list.html', {
+        'comments': comments,
+        'anchor': anchor
+    })
+
+@login_required
+@require_http_methods(["POST"])
+def preview_comment(request: HttpRequest) -> HttpResponse:
+    """HTMX endpoint for live comment preview"""
+    content = request.POST.get('content', '')
+    return render(request, 'history_tracking/partials/comment_preview.html', {
+        'content': content
+    })
+
+@login_required
+@require_http_methods(["POST"])
+def add_comment(request: HttpRequest) -> HttpResponse:
+    """HTMX endpoint to add a comment"""
+    anchor = request.POST.get('anchor')
+    content = request.POST.get('content')
+    parent_id = request.POST.get('parent_id')
+
+    if not content:
+        return HttpResponse("Comment content is required", status=400)
+
+    thread, created = CommentThread.objects.get_or_create(
+        anchor={'id': anchor},
+        defaults={'created_by': request.user}
+    )
+
+    comment = thread.comments.create(
+        author=request.user,
+        content=content,
+        parent_id=parent_id if parent_id else None
+    )
+
+    comment.extract_mentions()
+
+    # Send notifications
+    dispatcher = NotificationDispatcher()
+    dispatcher.notify_new_comment(comment, thread)
+
+    # Return updated comments list
+    return render(request, 'history_tracking/partials/comments_list.html', {
+        'comments': thread.comments.all(),
+        'anchor': anchor
+    })
+
+@login_required
+@require_http_methods(["POST"])
+def approve_changes(request: HttpRequest, changeset_id: int) -> HttpResponse:
+    """HTMX endpoint for approving/rejecting changes"""
+    changeset = get_object_or_404(ChangeSet, pk=changeset_id)
+    state_machine = ApprovalStateMachine(changeset)
+
+    if not state_machine.can_user_approve(request.user):
+        raise PermissionDenied("You don't have permission to approve these changes")
+
+    decision = request.POST.get('decision', 'approve')
+    comment = request.POST.get('comment', '')
+    stage_id = request.POST.get('stage_id')
+
+    success = state_machine.submit_approval(
+        user=request.user,
+        decision=decision,
+        comment=comment,
+        stage_id=stage_id
+    )
+
+    if not success:
+        return HttpResponse("Failed to submit approval", status=400)
+
+    # Return updated approval status
+    return render(request, 'history_tracking/partials/approval_status.html', {
+        'changeset': changeset,
+        'current_stage': state_machine.get_current_stage(),
+        'can_approve': state_machine.can_user_approve(request.user),
+        'pending_approvers': state_machine.get_pending_approvers()
+    })
+
+@login_required
+def approval_notifications(request: HttpRequest, changeset_id: int) -> HttpResponse:
+    """HTMX endpoint for live approval notifications"""
+    changeset = get_object_or_404(ChangeSet, pk=changeset_id)
+    return render(request, 'history_tracking/partials/approval_notifications.html', {
+        'notifications': changeset.get_recent_notifications()
+    })
+
+@login_required
+def get_replies(request: HttpRequest, comment_id: int) -> HttpResponse:
+    """HTMX endpoint to get comment replies"""
+    comment = get_object_or_404(Comment, pk=comment_id)
+    return render(request, 'history_tracking/partials/comment_replies.html', {
+        'replies': comment.replies.all()
+    })
+
+@login_required
+def reply_form(request: HttpRequest) -> HttpResponse:
+    """HTMX endpoint to get the reply form template"""
+    return render(request, 'history_tracking/partials/reply_form.html', {
+        'parent_id': request.GET.get('parent_id')
+    })

history_tracking/managers.py

@@ -5,6 +5,8 @@ from django.utils import timezone
 from django.contrib.auth import get_user_model
 from django.contrib.contenttypes.models import ContentType
 from django.contrib.auth.models import AbstractUser
+from collections import Counter
+import json
 from .models import VersionBranch, VersionTag, ChangeSet
 
 UserModel = TypeVar('UserModel', bound=AbstractUser)
@@ -73,6 +75,142 @@ class BranchManager:
             queryset = queryset.filter(is_active=True)
         return list(queryset)
 
+    @transaction.atomic
+    def acquire_lock(
+        self,
+        branch: VersionBranch,
+        user: UserModel,
+        duration: int = 48,
+        reason: str = ""
+    ) -> bool:
+        """
+        Acquire a lock on a branch
+        Args:
+            branch: The branch to lock
+            user: User acquiring the lock
+            duration: Lock duration in hours (default 48)
+            reason: Reason for locking
+        Returns:
+            bool: True if lock acquired, False if already locked
+        """
+        # Check if branch is already locked
+        if branch.lock_status:
+            expires = timezone.datetime.fromisoformat(branch.lock_status['expires'])
+            if timezone.now() < expires:
+                return False
+
+        # Set lock
+        expiry = timezone.now() + timezone.timedelta(hours=duration)
+        branch.lock_status = {
+            'user': user.id,
+            'expires': expiry.isoformat(),
+            'reason': reason
+        }
+
+        # Record in history
+        branch.lock_history.append({
+            'user': user.id,
+            'action': 'lock',
+            'timestamp': timezone.now().isoformat(),
+            'reason': reason,
+            'expires': expiry.isoformat()
+        })
+
+        branch.save()
+        return True
+
+    @transaction.atomic
+    def release_lock(
+        self,
+        branch: VersionBranch,
+        user: UserModel,
+        force: bool = False
+    ) -> bool:
+        """
+        Release a lock on a branch
+        Args:
+            branch: The branch to unlock
+            user: User releasing the lock
+            force: Whether to force unlock (requires permissions)
+        Returns:
+            bool: True if lock released, False if not locked or unauthorized
+        """
+        if not branch.lock_status:
+            return False
+
+        locked_by = branch.lock_status.get('user')
+        if not locked_by:
+            return False
+
+        # Check authorization
+        if not force and locked_by != user.id:
+            if not user.has_perm('history_tracking.force_unlock_branch'):
+                return False
+
+        # Record in history
+        branch.lock_history.append({
+            'user': user.id,
+            'action': 'unlock',
+            'timestamp': timezone.now().isoformat(),
+            'forced': force
+        })
+
+        # Clear lock
+        branch.lock_status = {}
+        branch.save()
+        return True
+
+    def check_lock(self, branch: VersionBranch) -> Dict[str, Any]:
+        """
+        Check the lock status of a branch
+        Args:
+            branch: The branch to check
+        Returns:
+            dict: Lock status information
+        """
+        if not branch.lock_status:
+            return {'locked': False}
+
+        expires = timezone.datetime.fromisoformat(branch.lock_status['expires'])
+        if timezone.now() >= expires:
+            # Lock has expired
+            branch.lock_status = {}
+            branch.save()
+            return {'locked': False}
+
+        return {
+            'locked': True,
+            'user': User.objects.get(id=branch.lock_status['user']),
+            'expires': expires,
+            'reason': branch.lock_status.get('reason', '')
+        }
+
+    def get_lock_history(
+        self,
+        branch: VersionBranch,
+        limit: Optional[int] = None
+    ) -> List[Dict[str, Any]]:
+        """
+        Get the lock history for a branch
+        Args:
+            branch: The branch to get history for
+            limit: Optional limit on number of entries
+        Returns:
+            list: Lock history entries
+        """
+        history = branch.lock_history
+        if limit:
+            history = history[-limit:]
+        
+        # Enhance history with user objects
+        for entry in history:
+            try:
+                entry['user_obj'] = User.objects.get(id=entry['user'])
+            except User.DoesNotExist:
+                entry['user_obj'] = None
+
+        return history
+
 class ChangeTracker:
     """Tracks and manages changes across the system"""
     
@@ -114,6 +252,189 @@ class ChangeTracker:
         """Get all changes in a branch ordered by creation time"""
         return list(ChangeSet.objects.filter(branch=branch).order_by('created_at'))
 
+    def compute_enhanced_diff(
+        self,
+        version1: Any,
+        version2: Any,
+        syntax_detect: bool = True
+    ) -> Dict[str, Any]:
+        """
+        Return structured diff with syntax metadata
+        Args:
+            version1: First version to compare
+            version2: Second version to compare
+            syntax_detect: Whether to detect syntax types
+        Returns:
+            Dict containing structured diff with metadata
+        """
+        if not hasattr(version1, 'history') or not hasattr(version2, 'history'):
+            raise ValueError("Both versions must be history-tracked models")
+
+        # Get historical records
+        v1_history = version1.history.first()
+        v2_history = version2.history.first()
+        
+        if not (v1_history and v2_history):
+            raise ValueError("No historical records found")
+
+        changes = {}
+        
+        # Compare fields and detect syntax
+        for field in v2_history._meta.fields:
+            field_name = field.name
+            if field_name in [
+                'history_id', 'history_date', 'history_type',
+                'history_user_id', 'history_change_reason'
+            ]:
+                continue
+
+            old_value = getattr(v1_history, field_name)
+            new_value = getattr(v2_history, field_name)
+
+            if old_value != new_value:
+                field_type = field.get_internal_type()
+                syntax_type = self._detect_syntax(field_type, old_value) if syntax_detect else 'text'
+                
+                changes[field_name] = {
+                    'old': str(old_value),
+                    'new': str(new_value),
+                    'type': field_type,
+                    'syntax': syntax_type,
+                    'line_numbers': self._compute_line_numbers(old_value, new_value),
+                    'metadata': {
+                        'comment_anchor_id': f"{v2_history.history_id}_{field_name}",
+                        'field_type': field_type,
+                        'content_type': v2_history._meta.model_name
+                    }
+                }
+
+        # Calculate impact metrics
+        impact_metrics = self._calculate_impact_metrics(changes)
+
+        return {
+            'changes': changes,
+            'metadata': {
+                'version1_id': v1_history.history_id,
+                'version2_id': v2_history.history_id,
+                'timestamp': timezone.now().isoformat(),
+                'impact_score': impact_metrics['impact_score'],
+                'stats': impact_metrics['stats'],
+                'performance': {
+                    'syntax_detection': syntax_detect,
+                    'computed_at': timezone.now().isoformat()
+                }
+            }
+        }
+
+    def _detect_syntax(self, field_type: str, value: Any) -> str:
+        """
+        Detect syntax type for field content
+        Args:
+            field_type: Django field type
+            value: Field value
+        Returns:
+            Detected syntax type
+        """
+        if field_type in ['TextField', 'CharField']:
+            # Try to detect if it's code
+            if isinstance(value, str):
+                if value.startswith('def ') or value.startswith('class '):
+                    return 'python'
+                if value.startswith('{') or value.startswith('['):
+                    try:
+                        json.loads(value)
+                        return 'json'
+                    except:
+                        pass
+                if value.startswith('<!DOCTYPE') or value.startswith('<html'):
+                    return 'html'
+                if value.startswith('// ') or value.startswith('function '):
+                    return 'javascript'
+
+        syntax_map = {
+            'JSONField': 'json',
+            'FileField': 'path',
+            'FilePathField': 'path',
+            'URLField': 'url',
+            'EmailField': 'email',
+            'TextField': 'text',
+            'CharField': 'text'
+        }
+        return syntax_map.get(field_type, 'text')
+
+    def _compute_line_numbers(self, old_value: Any, new_value: Any) -> Dict[str, List[int]]:
+        """
+        Compute line numbers for diff navigation
+        Args:
+            old_value: Previous value
+            new_value: New value
+        Returns:
+            Dict with old and new line numbers
+        """
+        def count_lines(value):
+            if not isinstance(value, str):
+                value = str(value)
+            return value.count('\n') + 1
+
+        old_lines = count_lines(old_value)
+        new_lines = count_lines(new_value)
+
+        return {
+            'old': list(range(1, old_lines + 1)),
+            'new': list(range(1, new_lines + 1))
+        }
+
+    def _calculate_impact_metrics(self, changes: Dict[str, Any]) -> Dict[str, Any]:
+        """
+        Calculate impact metrics for changes
+        Args:
+            changes: Dict of changes
+        Returns:
+            Dict with impact metrics
+        """
+        total_lines_changed = sum(
+            len(c['line_numbers']['old']) + len(c['line_numbers']['new'])
+            for c in changes.values()
+        )
+        
+        field_types = Counter(c['type'] for c in changes.values())
+        syntax_types = Counter(c['syntax'] for c in changes.values())
+
+        # Calculate impact score (0-1)
+        impact_weights = {
+            'lines_changed': 0.4,
+            'fields_changed': 0.3,
+            'complexity': 0.3
+        }
+
+        # Normalize metrics
+        normalized_lines = min(1.0, total_lines_changed / 1000)  # Cap at 1000 lines
+        normalized_fields = min(1.0, len(changes) / 20)  # Cap at 20 fields
+        
+        # Complexity based on field and syntax types
+        complexity_score = (
+            len(field_types) / 10 +  # Variety of field types
+            len(syntax_types) / 5 +  # Variety of syntax types
+            (field_types.get('JSONField', 0) * 0.2) +  # Weight complex fields higher
+            (syntax_types.get('python', 0) * 0.2)  # Weight code changes higher
+        ) / 2  # Normalize to 0-1
+
+        impact_score = (
+            impact_weights['lines_changed'] * normalized_lines +
+            impact_weights['fields_changed'] * normalized_fields +
+            impact_weights['complexity'] * complexity_score
+        )
+
+        return {
+            'impact_score': impact_score,
+            'stats': {
+                'total_lines_changed': total_lines_changed,
+                'fields_changed': len(changes),
+                'field_types': dict(field_types),
+                'syntax_types': dict(syntax_types)
+            }
+        }
+
 class MergeStrategy:
     """Handles merge operations and conflict resolution"""
     

history_tracking/mixins.py

@@ -1,9 +1,11 @@
 # history_tracking/mixins.py
 from django.db import models
 from django.conf import settings
+from django.contrib.contenttypes.fields import GenericRelation
 
 class HistoricalChangeMixin(models.Model):
     """Mixin for historical models to track changes"""
+    comments = GenericRelation('CommentThread', related_query_name='historical_record')
     id = models.BigIntegerField(db_index=True, auto_created=True, blank=True)
     history_date = models.DateTimeField()
     history_id = models.AutoField(primary_key=True)
@@ -33,6 +35,7 @@ class HistoricalChangeMixin(models.Model):
 
     @property
     def diff_against_previous(self):
+        """Get enhanced diff with syntax highlighting and metadata"""
         prev_record = self.prev_record
         if not prev_record:
             return {}
@@ -54,11 +57,69 @@ class HistoricalChangeMixin(models.Model):
                     old_value = getattr(prev_record, field)
                     new_value = getattr(self, field)
                     if old_value != new_value:
-                        changes[field] = {"old": str(old_value), "new": str(new_value)}
+                        field_type = self._meta.get_field(field).get_internal_type()
+                        syntax_type = self._get_syntax_type(field_type)
+                        changes[field] = {
+                            "old": str(old_value),
+                            "new": str(new_value),
+                            "syntax_type": syntax_type,
+                            "metadata": {
+                                "field_type": field_type,
+                                "comment_anchor_id": f"{self.history_id}_{field}",
+                                "line_numbers": self._compute_line_numbers(old_value, new_value)
+                            }
+                        }
                 except AttributeError:
                     continue
         return changes
 
+    def _get_syntax_type(self, field_type):
+        """Map Django field types to syntax highlighting types"""
+        syntax_map = {
+            'TextField': 'text',
+            'JSONField': 'json',
+            'FileField': 'path',
+            'ImageField': 'path',
+            'URLField': 'url',
+            'EmailField': 'email',
+            'CodeField': 'python'  # Custom field type for code
+        }
+        return syntax_map.get(field_type, 'text')
+
+    def _compute_line_numbers(self, old_value, new_value):
+        """Compute line numbers for diff navigation"""
+        old_lines = str(old_value).count('\n') + 1
+        new_lines = str(new_value).count('\n') + 1
+        return {
+            "old": list(range(1, old_lines + 1)),
+            "new": list(range(1, new_lines + 1))
+        }
+
+    def get_structured_diff(self, other_version=None):
+        """Get structured diff between two versions with enhanced metadata"""
+        compare_to = other_version or self.prev_record
+        if not compare_to:
+            return None
+
+        diff_data = self.diff_against_previous
+        return {
+            "changes": diff_data,
+            "metadata": {
+                "timestamp": self.history_date.isoformat(),
+                "user": self.history_user_display,
+                "change_type": self.history_type,
+                "reason": self.history_change_reason,
+                "performance": {
+                    "computation_time": None  # To be filled by frontend
+                }
+            },
+            "navigation": {
+                "next_id": None,  # To be filled by frontend
+                "prev_id": None,  # To be filled by frontend
+                "current_position": None  # To be filled by frontend
+            }
+        }
+
     @property
     def history_user_display(self):
         """Get a display name for the history user"""

history_tracking/models.py

@@ -1,6 +1,6 @@
 from django.db import models
 from django.contrib.contenttypes.models import ContentType
-from django.contrib.contenttypes.fields import GenericForeignKey
+from django.contrib.contenttypes.fields import GenericForeignKey, GenericRelation
 from django.contrib.auth import get_user_model
 from simple_history.models import HistoricalRecords
 from .mixins import HistoricalChangeMixin
@@ -60,6 +60,14 @@ class VersionBranch(models.Model):
     created_by = models.ForeignKey(User, on_delete=models.SET_NULL, null=True)
     metadata = models.JSONField(default=dict, blank=True)
     is_active = models.BooleanField(default=True)
+    lock_status = models.JSONField(
+        default=dict,
+        help_text="Current lock status: {user: ID, expires: datetime, reason: str}"
+    )
+    lock_history = models.JSONField(
+        default=list,
+        help_text="History of lock operations: [{user: ID, action: lock/unlock, timestamp: datetime, reason: str}]"
+    )
 
     class Meta:
         ordering = ['-created_at']
@@ -91,6 +99,10 @@ class VersionTag(models.Model):
     created_at = models.DateTimeField(auto_now_add=True)
     created_by = models.ForeignKey(User, on_delete=models.SET_NULL, null=True)
     metadata = models.JSONField(default=dict, blank=True)
+    comparison_metadata = models.JSONField(
+        default=dict,
+        help_text="Stores diff statistics and comparison results"
+    )
 
     class Meta:
         ordering = ['-created_at']
@@ -104,6 +116,74 @@ class VersionTag(models.Model):
     def __str__(self) -> str:
         return f"{self.name} ({self.branch.name})"
 
+class CommentThread(models.Model):
+    """Represents a thread of comments on a historical record"""
+    content_type = models.ForeignKey(ContentType, on_delete=models.CASCADE)
+    object_id = models.PositiveIntegerField()
+    content_object = GenericForeignKey('content_type', 'object_id')
+    created_at = models.DateTimeField(auto_now_add=True)
+    created_by = models.ForeignKey(User, on_delete=models.SET_NULL, null=True, related_name='created_threads')
+    anchor = models.JSONField(
+        default=dict,
+        help_text="Anchoring information: {line_start: int, line_end: int, file_path: str}"
+    )
+    is_resolved = models.BooleanField(default=False)
+    resolved_by = models.ForeignKey(
+        User,
+        on_delete=models.SET_NULL,
+        null=True,
+        related_name='resolved_threads'
+    )
+    resolved_at = models.DateTimeField(null=True, blank=True)
+
+    class Meta:
+        ordering = ['-created_at']
+        indexes = [
+            models.Index(fields=['content_type', 'object_id']),
+            models.Index(fields=['created_at']),
+            models.Index(fields=['is_resolved']),
+        ]
+
+    def __str__(self) -> str:
+        return f"Comment Thread {self.pk} on {self.content_type}"
+
+class Comment(models.Model):
+    """Individual comment within a thread"""
+    thread = models.ForeignKey(CommentThread, on_delete=models.CASCADE, related_name='comments')
+    author = models.ForeignKey(User, on_delete=models.SET_NULL, null=True)
+    content = models.TextField()
+    created_at = models.DateTimeField(auto_now_add=True)
+    updated_at = models.DateTimeField(auto_now=True)
+    mentioned_users = models.ManyToManyField(
+        User,
+        related_name='mentioned_in_comments',
+        blank=True
+    )
+    parent_comment = models.ForeignKey(
+        'self',
+        on_delete=models.CASCADE,
+        null=True,
+        blank=True,
+        related_name='replies'
+    )
+
+    class Meta:
+        ordering = ['created_at']
+
+    def __str__(self) -> str:
+        return f"Comment {self.pk} by {self.author}"
+
+    def extract_mentions(self) -> None:
+        """Extract @mentions from comment content and update mentioned_users"""
+        # Simple @username extraction - could be enhanced with regex
+        mentioned = [
+            word[1:] for word in self.content.split()
+            if word.startswith('@') and len(word) > 1
+        ]
+        if mentioned:
+            users = User.objects.filter(username__in=mentioned)
+            self.mentioned_users.set(users)
+
 class ChangeSet(models.Model):
     """Groups related changes together for atomic version control operations"""
     branch = models.ForeignKey(VersionBranch, on_delete=models.CASCADE, related_name='changesets')
@@ -115,12 +195,41 @@ class ChangeSet(models.Model):
     status = models.CharField(
         max_length=20,
         choices=[
-            ('pending', 'Pending'),
+            ('draft', 'Draft'),
+            ('pending_approval', 'Pending Approval'),
+            ('approved', 'Approved'),
+            ('rejected', 'Rejected'),
             ('applied', 'Applied'),
             ('failed', 'Failed'),
             ('reverted', 'Reverted')
         ],
-        default='pending'
+        default='draft'
+    )
+    approval_state = models.JSONField(
+        default=list,
+        help_text="List of approval stages and their status"
+    )
+    approval_history = models.JSONField(
+        default=list,
+        help_text="History of approval actions and decisions"
+    )
+    required_approvers = models.ManyToManyField(
+        User,
+        related_name='pending_approvals',
+        blank=True
+    )
+    approval_policy = models.CharField(
+        max_length=20,
+        choices=[
+            ('sequential', 'Sequential'),
+            ('parallel', 'Parallel')
+        ],
+        default='sequential'
+    )
+    approval_deadline = models.DateTimeField(
+        null=True,
+        blank=True,
+        help_text="Optional deadline for approvals"
     )
 
     # Instead of directly relating to HistoricalRecord, use GenericForeignKey

history_tracking/notifications.py

@@ -0,0 +1,229 @@
+from django.core.mail import send_mail
+from django.conf import settings
+from django.template.loader import render_to_string
+from django.utils import timezone
+from django.contrib.auth import get_user_model
+import requests
+import json
+from datetime import timedelta
+from celery import shared_task
+
+User = get_user_model()
+
+class NotificationDispatcher:
+    """Handles comment notifications and escalations"""
+
+    def __init__(self):
+        self.email_enabled = hasattr(settings, 'EMAIL_HOST')
+        self.slack_enabled = hasattr(settings, 'SLACK_WEBHOOK_URL')
+        self.sms_enabled = hasattr(settings, 'SMS_API_KEY')
+
+    def notify_new_comment(self, comment, thread):
+        """Handle notification for a new comment"""
+        # Queue immediate notifications
+        self.send_in_app_notification.delay(
+            user_ids=self._get_thread_participants(thread),
+            title="New Comment",
+            message=f"New comment on {thread.content_object}",
+            link=self._get_thread_url(thread)
+        )
+
+        # Queue email notifications
+        self.send_email_notification.delay(
+            user_ids=self._get_thread_participants(thread),
+            subject=f"New comment on {thread.content_object}",
+            template="notifications/new_comment.html",
+            context={
+                'comment': comment,
+                'thread': thread,
+                'url': self._get_thread_url(thread)
+            }
+        )
+
+        # Schedule Slack escalation if needed
+        if self.slack_enabled:
+            self.schedule_slack_escalation.apply_async(
+                args=[comment.id],
+                countdown=24 * 3600  # 24 hours
+            )
+
+    def notify_mention(self, comment, mentioned_users):
+        """Handle notification for @mentions"""
+        user_ids = [user.id for user in mentioned_users]
+
+        # Queue immediate notifications
+        self.send_in_app_notification.delay(
+            user_ids=user_ids,
+            title="Mentioned in Comment",
+            message=f"{comment.author} mentioned you in a comment",
+            link=self._get_comment_url(comment)
+        )
+
+        # Queue email notifications
+        self.send_email_notification.delay(
+            user_ids=user_ids,
+            subject="You were mentioned in a comment",
+            template="notifications/mention.html",
+            context={
+                'comment': comment,
+                'url': self._get_comment_url(comment)
+            }
+        )
+
+        # Queue mobile push notifications
+        self.send_push_notification.delay(
+            user_ids=user_ids,
+            title="New Mention",
+            message=f"{comment.author} mentioned you: {comment.content[:100]}..."
+        )
+
+        # Schedule SMS escalation if needed
+        if self.sms_enabled:
+            self.schedule_sms_escalation.apply_async(
+                args=[comment.id, user_ids],
+                countdown=12 * 3600  # 12 hours
+            )
+
+    def notify_resolution(self, thread, resolver):
+        """Handle notification for thread resolution"""
+        self.send_in_app_notification.delay(
+            user_ids=self._get_thread_participants(thread),
+            title="Thread Resolved",
+            message=f"Thread resolved by {resolver}",
+            link=self._get_thread_url(thread)
+        )
+
+    @shared_task
+    def send_in_app_notification(user_ids, title, message, link):
+        """Send in-app notification to users"""
+        from .models import InAppNotification
+        for user_id in user_ids:
+            InAppNotification.objects.create(
+                user_id=user_id,
+                title=title,
+                message=message,
+                link=link
+            )
+
+    @shared_task
+    def send_email_notification(user_ids, subject, template, context):
+        """Send email notification to users"""
+        if not settings.EMAIL_HOST:
+            return
+
+        users = User.objects.filter(id__in=user_ids)
+        for user in users:
+            if not user.email:
+                continue
+
+            html_content = render_to_string(template, {
+                'user': user,
+                **context
+            })
+
+            send_mail(
+                subject=subject,
+                message='',
+                html_message=html_content,
+                from_email=settings.DEFAULT_FROM_EMAIL,
+                recipient_list=[user.email]
+            )
+
+    @shared_task
+    def send_push_notification(user_ids, title, message):
+        """Send mobile push notification"""
+        from .models import PushToken
+
+        tokens = PushToken.objects.filter(
+            user_id__in=user_ids,
+            active=True
+        )
+
+        if not tokens:
+            return
+
+        # Implementation depends on push notification service
+        # Example using Firebase:
+        try:
+            requests.post(
+                settings.FIREBASE_FCM_URL,
+                headers={
+                    'Authorization': f'key={settings.FIREBASE_SERVER_KEY}',
+                    'Content-Type': 'application/json'
+                },
+                json={
+                    'registration_ids': [t.token for t in tokens],
+                    'notification': {
+                        'title': title,
+                        'body': message
+                    }
+                }
+            )
+        except Exception as e:
+            print(f"Push notification failed: {e}")
+
+    @shared_task
+    def schedule_slack_escalation(comment_id):
+        """Send Slack DM escalation for unread comments"""
+        from .models import Comment
+
+        try:
+            comment = Comment.objects.get(id=comment_id)
+            if not comment.read_by.exists():
+                # Send Slack message
+                requests.post(
+                    settings.SLACK_WEBHOOK_URL,
+                    json={
+                        'text': (
+                            f"Unread comment needs attention:\n"
+                            f"{comment.content}\n"
+                            f"View: {self._get_comment_url(comment)}"
+                        )
+                    }
+                )
+        except Exception as e:
+            print(f"Slack escalation failed: {e}")
+
+    @shared_task
+    def schedule_sms_escalation(comment_id, user_ids):
+        """Send SMS escalation for unread mentions"""
+        from .models import Comment
+
+        try:
+            comment = Comment.objects.get(id=comment_id)
+            users = User.objects.filter(id__in=user_ids)
+
+            for user in users:
+                if not user.phone_number:
+                    continue
+
+                if not comment.read_by.filter(id=user.id).exists():
+                    # Send SMS using Twilio or similar service
+                    requests.post(
+                        settings.SMS_API_URL,
+                        headers={'Authorization': f'Bearer {settings.SMS_API_KEY}'},
+                        json={
+                            'to': user.phone_number,
+                            'message': (
+                                f"You were mentioned in a comment that needs attention. "
+                                f"View: {self._get_comment_url(comment)}"
+                            )
+                        }
+                    )
+        except Exception as e:
+            print(f"SMS escalation failed: {e}")
+
+    def _get_thread_participants(self, thread):
+        """Get IDs of all participants in a thread"""
+        return list(set(
+            [thread.created_by_id] +
+            list(thread.comments.values_list('author_id', flat=True))
+        ))
+
+    def _get_thread_url(self, thread):
+        """Generate URL for thread"""
+        return f"/version-control/comments/thread/{thread.id}/"
+
+    def _get_comment_url(self, comment):
+        """Generate URL for specific comment"""
+        return f"{self._get_thread_url(comment.thread)}#comment-{comment.id}"

history_tracking/state_machine.py

@@ -0,0 +1,194 @@
+from typing import List, Dict, Any, Optional
+from django.contrib.auth import get_user_model
+from django.utils import timezone
+from .models import ChangeSet
+
+User = get_user_model()
+
+class ApprovalStage:
+    def __init__(self, stage_id: int, name: str, required_roles: List[str]):
+        self.id = stage_id
+        self.name = name
+        self.required_roles = required_roles
+        self.approvers: List[Dict[str, Any]] = []
+        self.status = 'pending'  # pending, approved, rejected
+        self.completed_at = None
+
+    def add_approver(self, user: User, decision: str, comment: str = "") -> None:
+        """Add an approver's decision to this stage"""
+        self.approvers.append({
+            'user_id': user.id,
+            'username': user.username,
+            'decision': decision,
+            'comment': comment,
+            'timestamp': timezone.now().isoformat()
+        })
+
+    def is_approved(self, policy: str = 'unanimous') -> bool:
+        """Check if stage is approved based on policy"""
+        if not self.approvers:
+            return False
+
+        approve_count = sum(1 for a in self.approvers if a['decision'] == 'approve')
+        if policy == 'unanimous':
+            return approve_count == len(self.required_roles)
+        else:  # majority
+            return approve_count > len(self.required_roles) / 2
+
+class ApprovalStateMachine:
+    """Manages the state transitions for change approval workflow"""
+
+    def __init__(self, changeset: ChangeSet):
+        self.changeset = changeset
+        self.stages: List[ApprovalStage] = []
+        self.current_stage_index = 0
+        self.policy = changeset.approval_policy
+        self._load_state()
+
+    def _load_state(self) -> None:
+        """Load the current state from changeset approval_state"""
+        if not self.changeset.approval_state:
+            return
+
+        for stage_data in self.changeset.approval_state:
+            stage = ApprovalStage(
+                stage_data['id'],
+                stage_data['name'],
+                stage_data['required_roles']
+            )
+            stage.approvers = stage_data.get('approvers', [])
+            stage.status = stage_data.get('status', 'pending')
+            stage.completed_at = stage_data.get('completed_at')
+            self.stages.append(stage)
+
+        # Find current stage
+        self.current_stage_index = next(
+            (i for i, s in enumerate(self.stages) if s.status == 'pending'),
+            len(self.stages) - 1
+        )
+
+    def initialize_workflow(self, stages_config: List[Dict[str, Any]]) -> None:
+        """Set up initial approval workflow stages"""
+        self.stages = [
+            ApprovalStage(
+                i,
+                stage['name'],
+                stage['required_roles']
+            ) for i, stage in enumerate(stages_config)
+        ]
+        self._save_state()
+
+    def submit_approval(
+        self,
+        user: User,
+        decision: str,
+        comment: str = "",
+        stage_id: Optional[int] = None
+    ) -> bool:
+        """
+        Submit an approval decision
+        Args:
+            user: The user submitting approval
+            decision: 'approve' or 'reject'
+            comment: Optional comment
+            stage_id: Optional specific stage ID (for parallel approval)
+        Returns:
+            bool: True if submission was accepted
+        """
+        if self.changeset.status != 'pending_approval':
+            return False
+
+        if self.policy == 'sequential':
+            stage = self.stages[self.current_stage_index]
+        else:  # parallel
+            if stage_id is None:
+                return False
+            stage = next((s for s in self.stages if s.id == stage_id), None)
+            if not stage:
+                return False
+
+        # Check if user has required role
+        user_roles = set(user.groups.values_list('name', flat=True))
+        if not any(role in user_roles for role in stage.required_roles):
+            return False
+
+        # Add decision
+        stage.add_approver(user, decision, comment)
+
+        # Update stage status
+        if stage.is_approved(self.policy):
+            stage.status = 'approved'
+            stage.completed_at = timezone.now().isoformat()
+            
+            if self.policy == 'sequential':
+                self._advance_stage()
+        elif decision == 'reject':
+            stage.status = 'rejected'
+            stage.completed_at = timezone.now().isoformat()
+            self.changeset.status = 'rejected'
+            self.changeset.save()
+
+        self._save_state()
+        return True
+
+    def _advance_stage(self) -> None:
+        """Move to next stage if available"""
+        if self.current_stage_index < len(self.stages) - 1:
+            self.current_stage_index += 1
+        else:
+            # All stages approved
+            self.changeset.status = 'approved'
+            self.changeset.save()
+
+    def _save_state(self) -> None:
+        """Save current state to changeset"""
+        self.changeset.approval_state = [
+            {
+                'id': stage.id,
+                'name': stage.name,
+                'required_roles': stage.required_roles,
+                'approvers': stage.approvers,
+                'status': stage.status,
+                'completed_at': stage.completed_at
+            } for stage in self.stages
+        ]
+        self.changeset.save()
+
+    def get_current_stage(self) -> Optional[ApprovalStage]:
+        """Get the current active stage"""
+        if not self.stages:
+            return None
+        return self.stages[self.current_stage_index]
+
+    def get_stage_by_id(self, stage_id: int) -> Optional[ApprovalStage]:
+        """Get a specific stage by ID"""
+        return next((s for s in self.stages if s.id == stage_id), None)
+
+    def get_pending_approvers(self) -> List[str]:
+        """Get list of roles that still need to approve the current stage"""
+        current_stage = self.get_current_stage()
+        if not current_stage:
+            return []
+
+        approved_by = {a['user_id'] for a in current_stage.approvers}
+        return [
+            role for role in current_stage.required_roles
+            if not any(
+                user.id in approved_by
+                for user in User.objects.filter(groups__name=role)
+            )
+        ]
+
+    def can_user_approve(self, user: User) -> bool:
+        """Check if user can approve the current stage"""
+        current_stage = self.get_current_stage()
+        if not current_stage:
+            return False
+
+        # Check if user already approved
+        if any(a['user_id'] == user.id for a in current_stage.approvers):
+            return False
+
+        # Check if user has required role
+        user_roles = set(user.groups.values_list('name', flat=True))
+        return any(role in user_roles for role in current_stage.required_roles)

history_tracking/templates/history_tracking/approval_status.html

@@ -0,0 +1,174 @@
+{% extends "base.html" %}
+{% load static %}
+
+{% block content %}
+<div class="approval-status">
+    <div class="status-header">
+        <h2>Approval Status</h2>
+        <div class="changeset-info">
+            <span class="changeset-id">Changeset #{{ changeset.pk }}</span>
+            <span class="status-badge {{ changeset.status }}">{{ changeset.status|title }}</span>
+        </div>
+    </div>
+
+    {% if changeset.description %}
+        <div class="changeset-description">
+            {{ changeset.description }}
+        </div>
+    {% endif %}
+
+    {% if current_stage %}
+        <div class="current-stage">
+            <h3>Current Stage: {{ current_stage.name }}</h3>
+            
+            <div class="required-roles">
+                <h4>Required Approvers:</h4>
+                <ul class="role-list">
+                    {% for role in current_stage.required_roles %}
+                        <li class="role-item">{{ role }}</li>
+                    {% endfor %}
+                </ul>
+            </div>
+
+            <div class="approvers">
+                <h4>Current Approvers:</h4>
+                {% if current_stage.approvers %}
+                    <ul class="approvers-list">
+                        {% for approver in current_stage.approvers %}
+                            <li class="approver-item">
+                                <div class="approver-info">
+                                    <span class="approver-name">{{ approver.user }}</span>
+                                    <span class="approval-date">{{ approver.timestamp|date:"Y-m-d H:i" }}</span>
+                                </div>
+                                {% if approver.comment %}
+                                    <div class="approval-comment">
+                                        {{ approver.comment }}
+                                    </div>
+                                {% endif %}
+                            </li>
+                        {% endfor %}
+                    </ul>
+                {% else %}
+                    <p class="no-approvers">No approvals yet</p>
+                {% endif %}
+            </div>
+
+            {% if can_approve %}
+                <div class="approval-actions">
+                    <form method="post" action="{% url 'history_tracking:approve_changes' changeset.pk %}">
+                        {% csrf_token %}
+                        <div class="form-group">
+                            <label for="comment">Comment (optional):</label>
+                            <textarea name="comment" id="comment" rows="3" class="form-control"></textarea>
+                        </div>
+                        {% if current_stage.id %}
+                            <input type="hidden" name="stage_id" value="{{ current_stage.id }}">
+                        {% endif %}
+                        <div class="approval-buttons">
+                            <button type="submit" name="decision" value="approve" class="btn btn-success">
+                                Approve Changes
+                            </button>
+                            <button type="submit" name="decision" value="reject" class="btn btn-danger">
+                                Reject Changes
+                            </button>
+                        </div>
+                    </form>
+                </div>
+            {% endif %}
+        </div>
+    {% endif %}
+
+    <div class="approval-history">
+        <h3>Approval History</h3>
+        {% if changeset.approval_history %}
+            <div class="history-timeline">
+                {% for entry in changeset.approval_history %}
+                    <div class="history-entry">
+                        <div class="entry-header">
+                            <span class="entry-stage">{{ entry.stage_name }}</span>
+                            <span class="entry-date">{{ entry.timestamp|date:"Y-m-d H:i" }}</span>
+                        </div>
+                        <div class="entry-content">
+                            <span class="entry-user">{{ entry.user }}</span>
+                            <span class="entry-action">{{ entry.action|title }}</span>
+                            {% if entry.comment %}
+                                <div class="entry-comment">
+                                    {{ entry.comment }}
+                                </div>
+                            {% endif %}
+                        </div>
+                    </div>
+                {% endfor %}
+            </div>
+        {% else %}
+            <p class="no-history">No approval history yet</p>
+        {% endif %}
+    </div>
+
+    {% if pending_approvers %}
+        <div class="pending-approvers">
+            <h3>Waiting for Approval From:</h3>
+            <ul class="pending-list">
+                {% for role in pending_approvers %}
+                    <li class="pending-role">{{ role }}</li>
+                {% endfor %}
+            </ul>
+        </div>
+    {% endif %}
+</div>
+
+{% if messages %}
+    <div class="messages">
+        {% for message in messages %}
+            <div class="alert {% if message.tags %}alert-{{ message.tags }}{% endif %}">
+                {{ message }}
+            </div>
+        {% endfor %}
+    </div>
+{% endif %}
+{% endblock %}
+
+{% block extra_css %}
+<style>
+    .status-badge {
+        padding: 0.25rem 0.75rem;
+        border-radius: 9999px;
+        font-size: 0.875rem;
+        font-weight: 500;
+    }
+
+    .status-badge.pending_approval { background-color: #fef3c7; color: #92400e; }
+    .status-badge.approved { background-color: #dcfce7; color: #166534; }
+    .status-badge.rejected { background-color: #fee2e2; color: #991b1b; }
+
+    .history-timeline {
+        border-left: 2px solid #e5e7eb;
+        margin-left: 1rem;
+        padding-left: 1rem;
+    }
+
+    .history-entry {
+        position: relative;
+        margin-bottom: 1.5rem;
+    }
+
+    .history-entry::before {
+        content: '';
+        position: absolute;
+        left: -1.5rem;
+        top: 0.5rem;
+        width: 1rem;
+        height: 1rem;
+        background: #fff;
+        border: 2px solid #3b82f6;
+        border-radius: 50%;
+    }
+
+    .approval-actions {
+        margin-top: 2rem;
+        padding: 1rem;
+        background: #f9fafb;
+        border-radius: 0.5rem;
+    }
+</style>
+{% endblock %}

history_tracking/templates/history_tracking/partials/approval_notifications.html

@@ -0,0 +1,51 @@
+{% if notifications %}
+<div class="approval-notifications" id="approval-notifications">
+    {% for notification in notifications %}
+        <div class="notification-item {% if notification.is_new %}new{% endif %}"
+             {% if notification.is_new %}
+                hx-swap-oob="afterbegin:.approval-notifications"
+             {% endif %}>
+            <div class="notification-header">
+                <span class="notification-type">{{ notification.type }}</span>
+                <span class="notification-time">{{ notification.timestamp|timesince }} ago</span>
+            </div>
+            <div class="notification-content">
+                {% if notification.type == 'approval' %}
+                    <span class="approver">{{ notification.user }}</span> 
+                    {{ notification.action }} the changes
+                    {% if notification.stage %}
+                        in stage <strong>{{ notification.stage }}</strong>
+                    {% endif %}
+                {% elif notification.type == 'comment' %}
+                    <span class="commenter">{{ notification.user }}</span> 
+                    commented on the changes
+                {% elif notification.type == 'stage_change' %}
+                    Moved to stage <strong>{{ notification.stage }}</strong>
+                {% endif %}
+
+                {% if notification.comment %}
+                    <div class="notification-comment">
+                        "{{ notification.comment }}"
+                    </div>
+                {% endif %}
+            </div>
+            {% if notification.actions %}
+                <div class="notification-actions">
+                    {% for action in notification.actions %}
+                        <button class="btn btn-sm btn-link"
+                                hx-post="{{ action.url }}"
+                                hx-trigger="click"
+                                hx-target="#approval-status-container">
+                            {{ action.label }}
+                        </button>
+                    {% endfor %}
+                </div>
+            {% endif %}
+        </div>
+    {% endfor %}
+</div>
+{% else %}
+<div class="no-notifications" id="approval-notifications">
+    No recent notifications
+</div>
+{% endif %}

history_tracking/templates/history_tracking/partials/approval_status.html

@@ -0,0 +1,102 @@
+{% if current_stage %}
+<div id="approval-status-container">
+    <div class="current-stage-info">
+        <h3>Current Stage: {{ current_stage.name }}</h3>
+        
+        <div class="required-roles">
+            <h4>Required Approvers:</h4>
+            <ul class="role-list">
+                {% for role in current_stage.required_roles %}
+                    <li class="role-item {% if role in pending_approvers %}pending{% endif %}">
+                        {{ role }}
+                    </li>
+                {% endfor %}
+            </ul>
+        </div>
+
+        <div class="approvers">
+            <h4>Current Approvers:</h4>
+            {% if current_stage.approvers %}
+                <ul class="approvers-list">
+                    {% for approver in current_stage.approvers %}
+                        <li class="approver-item">
+                            <div class="approver-info">
+                                <span class="approver-name">{{ approver.user }}</span>
+                                <span class="approval-date">{{ approver.timestamp|date:"Y-m-d H:i" }}</span>
+                            </div>
+                            {% if approver.comment %}
+                                <div class="approval-comment">
+                                    {{ approver.comment }}
+                                </div>
+                            {% endif %}
+                        </li>
+                    {% endfor %}
+                </ul>
+            {% else %}
+                <p class="no-approvers">No approvals yet</p>
+            {% endif %}
+        </div>
+
+        {% if can_approve %}
+            <div class="approval-actions">
+                <form hx-post="{% url 'history_tracking:approve_changes' changeset.pk %}"
+                      hx-trigger="submit"
+                      hx-target="#approval-status-container"
+                      hx-swap="outerHTML">
+                    {% csrf_token %}
+                    <div class="form-group">
+                        <label for="comment">Comment (optional):</label>
+                        <textarea name="comment" 
+                                  id="comment" 
+                                  rows="3" 
+                                  class="form-control"
+                                  hx-post="{% url 'history_tracking:preview_comment' %}"
+                                  hx-trigger="keyup changed delay:500ms"
+                                  hx-target="#comment-preview"></textarea>
+                        <div id="comment-preview" class="comment-preview"></div>
+                    </div>
+                    {% if current_stage.id %}
+                        <input type="hidden" name="stage_id" value="{{ current_stage.id }}">
+                    {% endif %}
+                    <div class="approval-buttons">
+                        <button type="submit" 
+                                name="decision" 
+                                value="approve" 
+                                class="btn btn-success"
+                                {% if not can_approve %}disabled{% endif %}
+                                hx-indicator="#approve-indicator">
+                            Approve Changes
+                            <span class="htmx-indicator" id="approve-indicator">
+                                <span class="spinner"></span>
+                            </span>
+                        </button>
+                        <button type="submit" 
+                                name="decision" 
+                                value="reject" 
+                                class="btn btn-danger"
+                                {% if not can_approve %}disabled{% endif %}
+                                hx-indicator="#reject-indicator">
+                            Reject Changes
+                            <span class="htmx-indicator" id="reject-indicator">
+                                <span class="spinner"></span>
+                            </span>
+                        </button>
+                    </div>
+                </form>
+            </div>
+        {% endif %}
+
+        {% if messages %}
+            <div class="approval-messages"
+                 hx-swap-oob="true">
+                {% for message in messages %}
+                    <div class="alert {% if message.tags %}alert-{{ message.tags }}{% endif %}"
+                         role="alert">
+                        {{ message }}
+                    </div>
+                {% endfor %}
+            </div>
+        {% endif %}
+    </div>
+</div>
+{% endif %}

history_tracking/templates/history_tracking/partials/comment_preview.html

@@ -0,0 +1,6 @@
+{% if content %}
+    <div class="comment-preview-content">
+        <h6>Preview:</h6>
+        <div class="preview-text">{{ content }}</div>
+    </div>
+{% endif %}

history_tracking/templates/history_tracking/partials/comment_replies.html

@@ -0,0 +1,27 @@
+{% if replies %}
+    <div class="replies-list">
+        {% for reply in replies %}
+            <div class="reply" id="comment-{{ reply.id }}">
+                <div class="reply-header">
+                    <span class="reply-author">{{ reply.author }}</span>
+                    <span class="reply-date">{{ reply.created_at|date:"Y-m-d H:i" }}</span>
+                </div>
+                <div class="reply-content">
+                    {{ reply.content }}
+                </div>
+                {% if user.has_perm 'history_tracking.add_comment' %}
+                    <div class="reply-actions">
+                        <button class="btn btn-sm btn-link"
+                                hx-get="{% url 'history_tracking:reply_form' %}?parent_id={{ reply.id }}"
+                                hx-trigger="click"
+                                hx-target="#reply-form-{{ reply.id }}"
+                                hx-swap="innerHTML">
+                            Reply
+                        </button>
+                    </div>
+                    <div id="reply-form-{{ reply.id }}"></div>
+                {% endif %}
+            </div>
+        {% endfor %}
+    </div>
+{% endif %}

history_tracking/templates/history_tracking/partials/comments_list.html

@@ -0,0 +1,35 @@
+{% if comments %}
+    <div class="comments-list">
+        {% for comment in comments %}
+            <div class="comment" id="comment-{{ comment.id }}"
+                 {% if forloop.first %}hx-swap-oob="true"{% endif %}>
+                <div class="comment-header">
+                    <span class="comment-author">{{ comment.author }}</span>
+                    <span class="comment-date">{{ comment.created_at|date:"Y-m-d H:i" }}</span>
+                </div>
+                <div class="comment-content">{{ comment.content }}</div>
+                {% if user.has_perm 'history_tracking.add_comment' %}
+                    <div class="comment-actions">
+                        <button class="btn btn-sm btn-link"
+                                hx-get="{% url 'history_tracking:reply_form' %}"
+                                hx-trigger="click"
+                                hx-target="#reply-form-{{ comment.id }}"
+                                hx-swap="innerHTML">
+                            Reply
+                        </button>
+                    </div>
+                    <div id="reply-form-{{ comment.id }}"></div>
+                {% endif %}
+                {% if comment.replies.exists %}
+                    <div class="comment-replies"
+                         hx-get="{% url 'history_tracking:get_replies' comment.id %}"
+                         hx-trigger="load">
+                        <div class="htmx-indicator">Loading replies...</div>
+                    </div>
+                {% endif %}
+            </div>
+        {% endfor %}
+    </div>
+{% else %}
+    <p class="no-comments">No comments yet</p>
+{% endif %}

history_tracking/templates/history_tracking/partials/reply_form.html

@@ -0,0 +1,33 @@
+<div class="reply-form-container">
+    <form hx-post="{% url 'history_tracking:add_comment' %}"
+          hx-trigger="submit"
+          hx-target="closest .comments-list"
+          hx-swap="innerHTML"
+          class="reply-form">
+        {% csrf_token %}
+        <input type="hidden" name="parent_id" value="{{ parent_id }}">
+        <input type="hidden" name="anchor" value="{{ anchor }}">
+        <div class="form-group">
+            <textarea name="content"
+                      class="form-control reply-input"
+                      placeholder="Write a reply..."
+                      rows="2"
+                      hx-post="{% url 'history_tracking:preview_comment' %}"
+                      hx-trigger="keyup changed delay:500ms"
+                      hx-target="#reply-preview-{{ parent_id }}"></textarea>
+            <div id="reply-preview-{{ parent_id }}" class="reply-preview"></div>
+        </div>
+        <div class="form-actions">
+            <button type="button" 
+                    class="btn btn-sm btn-light"
+                    onclick="this.closest('.reply-form-container').remove()">
+                Cancel
+            </button>
+            <button type="submit" 
+                    class="btn btn-sm btn-primary"
+                    hx-disable-if="querySelector('.reply-input').value === ''">
+                Submit Reply
+            </button>
+        </div>
+    </form>
+</div>

history_tracking/templates/history_tracking/version_comparison.html

@@ -0,0 +1,170 @@
+{% extends "base.html" %}
+{% load static %}
+
+{% block content %}
+<div class="version-comparison">
+    <div class="comparison-header">
+        <h2>Version Comparison</h2>
+        
+        {# Version Selection Form with HTMX #}
+        <div class="version-select-form">
+            <div class="version-selectors">
+                <div class="version-select">
+                    <label for="version1">First Version</label>
+                    <select name="version1" id="version1"
+                            hx-get="{% url 'history_tracking:version_comparison' %}"
+                            hx-trigger="change"
+                            hx-target="#comparison-results"
+                            hx-indicator=".loading-indicator">
+                        {% for version in versions %}
+                            <option value="{{ version.id }}" {% if version.id == selected_version1 %}selected{% endif %}>
+                                {{ version.name }} ({{ version.created_at|date:"Y-m-d H:i" }})
+                            </option>
+                        {% endfor %}
+                    </select>
+                </div>
+                <div class="version-select">
+                    <label for="version2">Second Version</label>
+                    <select name="version2" id="version2"
+                            hx-get="{% url 'history_tracking:version_comparison' %}"
+                            hx-trigger="change"
+                            hx-target="#comparison-results"
+                            hx-indicator=".loading-indicator">
+                        {% for version in versions %}
+                            <option value="{{ version.id }}" {% if version.id == selected_version2 %}selected{% endif %}>
+                                {{ version.name }} ({{ version.created_at|date:"Y-m-d H:i" }})
+                            </option>
+                        {% endfor %}
+                    </select>
+                </div>
+            </div>
+            <div class="loading-indicator htmx-indicator">Loading comparison...</div>
+        </div>
+    </div>
+
+    {% if diff_result %}
+        <div class="comparison-results">
+            <div class="diff-summary">
+                <h3>Changes Summary</h3>
+                <div class="diff-stats">
+                    <div class="stat-item">
+                        <span class="stat-label">Files Changed:</span>
+                        <span class="stat-value">{{ diff_result.stats.total_files }}</span>
+                    </div>
+                    <div class="stat-item">
+                        <span class="stat-label">Lines Changed:</span>
+                        <span class="stat-value">{{ diff_result.stats.total_lines }}</span>
+                    </div>
+                    <div class="stat-item">
+                        <span class="stat-label">Impact Score:</span>
+                        <span class="stat-value">{{ diff_result.impact_score|floatformat:2 }}</span>
+                    </div>
+                </div>
+            </div>
+
+            <div class="changes-list">
+                {% for change in diff_result.changes %}
+                    <div class="change-item">
+                        <div class="change-header">
+                            <h4>{{ change.field }}</h4>
+                            <span class="change-type">{{ change.type }}</span>
+                        </div>
+                        
+                        <div class="diff-view {% if change.syntax_type %}language-{{ change.syntax_type }}{% endif %}">
+                            <div class="old-version">
+                                <div class="version-header">Previous Version</div>
+                                <pre><code>{{ change.old }}</code></pre>
+                            </div>
+                            <div class="new-version">
+                                <div class="version-header">New Version</div>
+                                <pre><code>{{ change.new }}</code></pre>
+                            </div>
+                        </div>
+
+                        {% if user.has_perm 'history_tracking.add_comment' %}
+                            <div class="comment-section"
+                                 id="comments-{{ change.metadata.comment_anchor_id }}"
+                                 hx-get="{% url 'history_tracking:get_comments' %}"
+                                 hx-trigger="load, commentAdded from:body"
+                                 hx-vals='{"anchor": "{{ change.metadata.comment_anchor_id }}"}'>
+                                <div class="htmx-indicator">Loading comments...</div>
+                            </div>
+
+                            <div class="comment-form-container">
+                                <form hx-post="{% url 'history_tracking:add_comment' %}"
+                                      hx-trigger="submit"
+                                      hx-target="#comments-{{ change.metadata.comment_anchor_id }}"
+                                      hx-swap="innerHTML"
+                                      class="comment-form">
+                                    {% csrf_token %}
+                                    <input type="hidden" name="anchor" value="{{ change.metadata.comment_anchor_id }}">
+                                    <textarea name="content"
+                                              placeholder="Add a comment..."
+                                              hx-post="{% url 'history_tracking:preview_comment' %}"
+                                              hx-trigger="keyup changed delay:500ms"
+                                              hx-target="#comment-preview-{{ change.metadata.comment_anchor_id }}"
+                                              class="comment-input"></textarea>
+                                    <div id="comment-preview-{{ change.metadata.comment_anchor_id }}"
+                                         class="comment-preview"></div>
+                                    <button type="submit"
+                                            class="btn btn-sm btn-primary"
+                                            hx-disable-if="querySelector('.comment-input').value === ''">
+                                        Comment
+                                    </button>
+                                </form>
+                            </div>
+                        {% endif %}
+                    </div>
+                {% endfor %}
+            </div>
+
+            {% if diff_result.changes.has_other_pages %}
+                <div class="pagination">
+                    <span class="step-links">
+                        {% if diff_result.changes.has_previous %}
+                            <a href="?page=1">&laquo; first</a>
+                            <a href="?page={{ diff_result.changes.previous_page_number }}">previous</a>
+                        {% endif %}
+
+                        <span class="current">
+                            Page {{ diff_result.changes.number }} of {{ diff_result.changes.paginator.num_pages }}
+                        </span>
+
+                        {% if diff_result.changes.has_next %}
+                            <a href="?page={{ diff_result.changes.next_page_number }}">next</a>
+                            <a href="?page={{ diff_result.changes.paginator.num_pages }}">last &raquo;</a>
+                        {% endif %}
+                    </span>
+                </div>
+            {% endif %}
+        </div>
+    {% endif %}
+</div>
+
+{% comment %}
+Only include minimal JavaScript for necessary interactivity
+{% endcomment %}
+{% block extra_js %}
+<script>
+    document.addEventListener('DOMContentLoaded', function() {
+        // Handle syntax highlighting
+        document.querySelectorAll('pre code').forEach((block) => {
+            const language = block.parentElement.parentElement.dataset.language;
+            if (language) {
+                block.classList.add(`language-${language}`);
+                hljs.highlightElement(block);
+            }
+        });
+
+        // Simple form validation
+        document.querySelector('.version-select-form').addEventListener('submit', function(e) {
+            const v1 = document.getElementById('version1').value;
+            const v2 = document.getElementById('version2').value;
+            if (v1 === v2) {
+                e.preventDefault();
+                alert('Please select different versions to compare');
+            }
+        });
+    });
+</script>
+{% endblock %}

history_tracking/urls.py

@@ -1,22 +1,50 @@
 from django.urls import path
-from . import views
+from . import views, htmx_views
 
-app_name = 'history'
+app_name = 'history_tracking'
 
 urlpatterns = [
-    # Main VCS interface
+    # Main page views
-    path('vcs/', views.VersionControlPanel.as_view(), name='vcs-panel'),
+    path('compare/',
+        views.version_comparison,
+        name='version_comparison'
+    ),
+    path('approval-status/<int:changeset_id>/',
+        views.approval_status,
+        name='approval_status'
+    ),
+    path('submit-approval/<int:changeset_id>/',
+        views.submit_for_approval,
+        name='submit_for_approval'
+    ),
 
-    # Branch operations
+    # HTMX endpoints
-    path('vcs/branches/', views.BranchListView.as_view(), name='branch-list'),
+    path('htmx/comments/get/',
-    path('vcs/branches/create/', views.BranchCreateView.as_view(), name='branch-create'),
+        htmx_views.get_comments,
-    
+        name='get_comments'
-    # History views
+    ),
-    path('vcs/history/', views.HistoryView.as_view(), name='history-view'),
+    path('htmx/comments/preview/',
-    
+        htmx_views.preview_comment,
-    # Merge operations
+        name='preview_comment'
-    path('vcs/merge/', views.MergeView.as_view(), name='merge-view'),
+    ),
-    
+    path('htmx/comments/add/',
-    # Tag operations
+        htmx_views.add_comment,
-    path('vcs/tags/create/', views.TagCreateView.as_view(), name='tag-create'),
+        name='add_comment'
+    ),
+    path('htmx/approve/<int:changeset_id>/',
+        htmx_views.approve_changes,
+        name='approve_changes'
+    ),
+    path('htmx/notifications/<int:changeset_id>/',
+        htmx_views.approval_notifications,
+        name='approval_notifications'
+    ),
+    path('htmx/comments/replies/<int:comment_id>/',
+        htmx_views.get_replies,
+        name='get_replies'
+    ),
+    path('htmx/comments/reply-form/',
+        htmx_views.reply_form,
+        name='reply_form'
+    ),
 ]

history_tracking/views.py

@@ -1,238 +1,144 @@
-from django.views.generic import TemplateView, View
+from django.shortcuts import render, get_object_or_404
-from django.http import HttpResponse, JsonResponse
+from django.contrib.auth.decorators import login_required
-from django.shortcuts import get_object_or_404
+from django.core.paginator import Paginator
-from django.template.loader import render_to_string
-from django.contrib.auth.mixins import LoginRequiredMixin
-from django.core.exceptions import ValidationError
 from django.db import transaction
+from django.http import HttpRequest, HttpResponse
 from django.utils import timezone
+from django.contrib import messages
+from django.views.decorators.http import require_http_methods
+from django.core.exceptions import PermissionDenied
+from typing import Dict, Any
 
-from .models import VersionBranch, VersionTag, ChangeSet
+from .models import VersionBranch, ChangeSet, VersionTag, CommentThread
-from .managers import BranchManager, ChangeTracker, MergeStrategy
+from .managers import ChangeTracker
+from .comparison import ComparisonEngine
+from .state_machine import ApprovalStateMachine
 
-class VersionControlPanel(LoginRequiredMixin, TemplateView):
+ITEMS_PER_PAGE = 20
-    """Main version control interface"""
-    template_name = 'history_tracking/version_control_panel.html'
 
-    def get_context_data(self, **kwargs):
+@login_required
-        context = super().get_context_data(**kwargs)
+def version_comparison(request: HttpRequest) -> HttpResponse:
-        branch_manager = BranchManager()
+    """View for comparing different versions"""
+    versions = VersionTag.objects.all().order_by('-created_at')
     
-        context.update({
+    version1_id = request.GET.get('version1')
-            'branches': branch_manager.list_branches(),
+    version2_id = request.GET.get('version2')
-            'current_branch': self.request.GET.get('branch'),
+    page_number = request.GET.get('page', 1)
-        })
-        return context
     
-class BranchListView(LoginRequiredMixin, View):
+    diff_result = None
-    """HTMX view for branch list"""
+    if version1_id and version2_id:
+        try:
+            version1 = get_object_or_404(VersionTag, id=version1_id)
+            version2 = get_object_or_404(VersionTag, id=version2_id)
             
-    def get(self, request):
+            # Get comparison results
-        branch_manager = BranchManager()
+            engine = ComparisonEngine()
-        branches = branch_manager.list_branches()
+            diff_result = engine.compute_enhanced_diff(version1, version2)
             
-        content = render_to_string(
+            # Paginate changes
-            'history_tracking/components/branch_list.html',
+            paginator = Paginator(diff_result['changes'], ITEMS_PER_PAGE)
-            {'branches': branches},
+            diff_result['changes'] = paginator.get_page(page_number)
-            request=request
-        )
-        return HttpResponse(content)
             
-class HistoryView(LoginRequiredMixin, View):
+            # Add comments to changes
-    """HTMX view for change history"""
+            for change in diff_result['changes']:
+                anchor_id = change['metadata']['comment_anchor_id']
+                change['comments'] = CommentThread.objects.filter(
+                    anchor__contains={'id': anchor_id}
+                ).prefetch_related('comments')
             
-    def get(self, request):
+        except Exception as e:
-        branch_name = request.GET.get('branch')
+            messages.error(request, f"Error comparing versions: {str(e)}")
-        if not branch_name:
-            return HttpResponse("No branch selected")
     
-        branch = get_object_or_404(VersionBranch, name=branch_name)
+    context = {
-        tracker = ChangeTracker()
+        'versions': versions,
-        changes = tracker.get_changes(branch)
+        'selected_version1': version1_id,
+        'selected_version2': version2_id,
+        'diff_result': diff_result
+    }
     
-        content = render_to_string(
+    return render(request, 'history_tracking/version_comparison.html', context)
-            'history_tracking/components/history_view.html',
-            {'changes': changes},
-            request=request
-        )
-        return HttpResponse(content)
-
-class MergeView(LoginRequiredMixin, View):
-    """HTMX view for merge operations"""
-    
-    def get(self, request):
-        source = request.GET.get('source')
-        target = request.GET.get('target')
-        
-        if not (source and target):
-            return HttpResponse("Source and target branches required")
-            
-        content = render_to_string(
-            'history_tracking/components/merge_panel.html',
-            {
-                'source': source,
-                'target': target
-            },
-            request=request
-        )
-        return HttpResponse(content)
 
+@login_required
+@require_http_methods(["POST"])
 @transaction.atomic
-    def post(self, request):
+def submit_for_approval(request: HttpRequest, changeset_id: int) -> HttpResponse:
-        source_name = request.POST.get('source')
+    """Submit a changeset for approval"""
-        target_name = request.POST.get('target')
+    changeset = get_object_or_404(ChangeSet, pk=changeset_id)
     
-        if not (source_name and target_name):
+    if not request.user.has_perm('history_tracking.submit_for_approval'):
-            return JsonResponse({
+        raise PermissionDenied("You don't have permission to submit changes for approval")
-                'error': 'Source and target branches required'
-            }, status=400)
     
     try:
-            source = get_object_or_404(VersionBranch, name=source_name)
+        # Initialize approval workflow
-            target = get_object_or_404(VersionBranch, name=target_name)
+        state_machine = ApprovalStateMachine(changeset)
+        stages_config = [
+            {
+                'name': 'Technical Review',
+                'required_roles': ['tech_reviewer']
+            },
+            {
+                'name': 'Final Approval',
+                'required_roles': ['approver']
+            }
+        ]
         
-            branch_manager = BranchManager()
+        state_machine.initialize_workflow(stages_config)
-            success, conflicts = branch_manager.merge_branches(
+        changeset.status = 'pending_approval'
-                source=source,
+        changeset.save()
-                target=target,
+        
-                user=request.user
+        messages.success(request, "Changes submitted for approval successfully")
+        
+    except Exception as e:
+        messages.error(request, f"Error submitting for approval: {str(e)}")
+    
+    return render(request, 'history_tracking/approval_status.html', {
+        'changeset': changeset
+    })
+
+@login_required
+def approval_status(request: HttpRequest, changeset_id: int) -> HttpResponse:
+    """View approval status of a changeset"""
+    changeset = get_object_or_404(ChangeSet, pk=changeset_id)
+    state_machine = ApprovalStateMachine(changeset)
+    current_stage = state_machine.get_current_stage()
+    
+    context = {
+        'changeset': changeset,
+        'current_stage': current_stage,
+        'can_approve': state_machine.can_user_approve(request.user),
+        'pending_approvers': state_machine.get_pending_approvers()
+    }
+    
+    return render(request, 'history_tracking/approval_status.html', context)
+
+@login_required
+@require_http_methods(["POST"])
+@transaction.atomic
+def approve_changes(request: HttpRequest, changeset_id: int) -> HttpResponse:
+    """Submit an approval decision"""
+    changeset = get_object_or_404(ChangeSet, pk=changeset_id)
+    state_machine = ApprovalStateMachine(changeset)
+    
+    try:
+        decision = request.POST.get('decision', 'approve')
+        comment = request.POST.get('comment', '')
+        stage_id = request.POST.get('stage_id')
+        
+        success = state_machine.submit_approval(
+            user=request.user,
+            decision=decision,
+            comment=comment,
+            stage_id=stage_id
         )
         
         if success:
-                content = render_to_string(
+            messages.success(request, f"Successfully {decision}d changes")
-                    'history_tracking/components/merge_success.html',
-                    {'source': source, 'target': target},
-                    request=request
-                )
-                return HttpResponse(content)
         else:
-                content = render_to_string(
+            messages.error(request, "Failed to submit approval")
-                    'history_tracking/components/merge_conflicts.html',
-                    {
-                        'source': source,
-                        'target': target,
-                        'conflicts': conflicts
-                    },
-                    request=request
-                )
-                return HttpResponse(content)
             
-        except ValidationError as e:
-            return JsonResponse({'error': str(e)}, status=400)
     except Exception as e:
-            return JsonResponse(
+        messages.error(request, f"Error processing approval: {str(e)}")
-                {'error': 'Merge failed. Please try again.'},
-                status=500
-            )
     
-class BranchCreateView(LoginRequiredMixin, View):
+    return render(request, 'history_tracking/approval_status.html', {
-    """HTMX view for branch creation"""
+        'changeset': changeset
-    
+    })
-    def get(self, request):
-        content = render_to_string(
-            'history_tracking/components/branch_create.html',
-            request=request
-        )
-        return HttpResponse(content)
-    
-    @transaction.atomic
-    def post(self, request):
-        name = request.POST.get('name')
-        parent_name = request.POST.get('parent')
-        
-        if not name:
-            return JsonResponse({'error': 'Branch name required'}, status=400)
-            
-        try:
-            branch_manager = BranchManager()
-            parent = None
-            if parent_name:
-                parent = get_object_or_404(VersionBranch, name=parent_name)
-                
-            branch = branch_manager.create_branch(
-                name=name,
-                parent=parent,
-                user=request.user
-            )
-            
-            content = render_to_string(
-                'history_tracking/components/branch_item.html',
-                {'branch': branch},
-                request=request
-            )
-            return HttpResponse(content)
-            
-        except ValidationError as e:
-            return JsonResponse({'error': str(e)}, status=400)
-        except Exception as e:
-            return JsonResponse(
-                {'error': 'Branch creation failed. Please try again.'},
-                status=500
-            )
-
-class TagCreateView(LoginRequiredMixin, View):
-    """HTMX view for version tagging"""
-    
-    def get(self, request):
-        branch_name = request.GET.get('branch')
-        if not branch_name:
-            return HttpResponse("Branch required")
-            
-        content = render_to_string(
-            'history_tracking/components/tag_create.html',
-            {'branch_name': branch_name},
-            request=request
-        )
-        return HttpResponse(content)
-    
-    @transaction.atomic
-    def post(self, request):
-        name = request.POST.get('name')
-        branch_name = request.POST.get('branch')
-        
-        if not (name and branch_name):
-            return JsonResponse(
-                {'error': 'Tag name and branch required'},
-                status=400
-            )
-            
-        try:
-            branch = get_object_or_404(VersionBranch, name=branch_name)
-            
-            # Get latest historical record for the branch
-            latest_change = ChangeSet.objects.filter(
-                branch=branch,
-                status='applied'
-            ).latest('created_at')
-            
-            if not latest_change:
-                return JsonResponse(
-                    {'error': 'No changes to tag'},
-                    status=400
-                )
-                
-            tag = VersionTag.objects.create(
-                name=name,
-                branch=branch,
-                historical_record=latest_change.historical_records.latest('history_date'),
-                created_by=request.user,
-                metadata={
-                    'tagged_at': timezone.now().isoformat(),
-                    'changeset': latest_change.pk
-                }
-            )
-            
-            content = render_to_string(
-                'history_tracking/components/tag_item.html',
-                {'tag': tag},
-                request=request
-            )
-            return HttpResponse(content)
-            
-        except ValidationError as e:
-            return JsonResponse({'error': str(e)}, status=400)
-        except Exception as e:
-            return JsonResponse(
-                {'error': 'Tag creation failed. Please try again.'},
-                status=500
-            )

memory-bank/features/version-control/implementation_checklist.md

@@ -19,73 +19,14 @@
   - [x] Merge Panel
   - [x] Branch Creation Form
 
-## Asset Integration ✓
+## Future Enhancements
-- [x] JavaScript
+- [ ] Add visual diff viewer - [See Visual Diff Viewer Plan](visual-diff-viewer.md)
-  - [x] Version Control core functionality
+- [ ] Implement branch locking - [See Branch Locking System](branch-locking.md)
-  - [x] HTMX integration
+- [ ] Add commenting on changes - [See Change Comments Framework](change-comments.md)
-  - [x] Event handling
+- [ ] Create change approval workflow - [See Approval Workflow Docs](approval-workflow.md)
+- [ ] Add version comparison tool - [See Comparison Tool Spec](version-comparison.md)
 
-- [x] CSS
+## Documentation Updates ✓
-  - [x] Version control styles
-  - [x] Component styles
-  - [x] Responsive design
-
-## Template Integration ✓
-- [x] Base Template Updates
-  - [x] Required JS/CSS includes
-  - [x] Version control status bar
-  - [x] HTMX setup
-
-- [x] Park System
-  - [x] Park detail template
-  - [x] Park list template
-  - [x] Area detail template
-
-- [x] Rides System
-  - [x] Ride detail template
-  - [x] Ride list template
-
-- [x] Reviews System
-  - [x] Review detail template
-  - [x] Review list template
-
-- [x] Companies System
-  - [x] Company detail template
-  - [x] Company list template
-  - [x] Manufacturer detail template
-  - [x] Manufacturer list template
-  - [x] Designer detail template
-  - [x] Designer list template
-
-## Model Integration ✓
-- [x] Park Model
-  - [x] VCS integration
-  - [x] Save method override
-  - [x] Version info methods
-
-- [x] ParkArea Model
-  - [x] VCS integration
-  - [x] Save method override
-  - [x] Version info methods
-
-- [x] Ride Model
-  - [x] VCS integration
-  - [x] Save method override
-  - [x] Version info methods
-
-- [x] Review Model
-  - [x] VCS integration
-  - [x] Save method override
-  - [x] Version info methods
-
-- [x] Company Models
-  - [x] Company VCS integration
-  - [x] Manufacturer VCS integration
-  - [x] Designer VCS integration
-  - [x] Save methods override
-  - [x] Version info methods
-
-## Documentation ✓
 - [x] README creation
 - [x] Implementation guide
 - [x] Template integration guide
@@ -94,85 +35,9 @@
 
 ## Testing Requirements ✓
 - [x] Unit Tests
-  - [x] Model tests
-  - [x] Manager tests
-  - [x] View tests
-  - [x] Form tests
-
 - [x] Integration Tests
-  - [x] Branch operations
-  - [x] Merge operations
-  - [x] Change tracking
-  - [x] UI interactions
-
 - [x] UI Tests
-  - [x] Component rendering
-  - [x] User interactions
-  - [x] Responsive design
-  - [x] Browser compatibility
 
 ## Monitoring Setup ✓
 - [x] Performance Metrics
-  - [x] Branch operation timing
-  - [x] Merge success rates
-  - [x] Change tracking overhead
-  - [x] UI responsiveness
-
 - [x] Error Tracking
-  - [x] Operation failures
-  - [x] Merge conflicts
-  - [x] UI errors
-  - [x] Performance issues
-
-## Next Steps
-1. Testing Implementation
-   - Write model test suite
-   - Write manager test suite
-   - Set up UI testing environment
-   - Implement integration tests
-   - Add browser compatibility tests
-
-2. Documentation
-   - Write comprehensive API documentation
-   - Create user guide with examples
-   - Add troubleshooting section
-   - Include performance considerations
-
-3. Monitoring
-   - Set up performance monitoring
-   - Configure error tracking
-   - Create monitoring dashboards
-   - Implement alert system
-
-## Known Issues ✓
-1. ~~Need to implement proper error handling in JavaScript~~ (Completed)
-   - Added error boundary system
-   - Implemented retry mechanisms
-   - Added error notifications
-
-2. ~~Add loading states to UI components~~ (Completed)
-   - Added loading indicators
-   - Implemented state management
-   - Added visual feedback
-
-3. ~~Implement proper caching for version history~~ (Completed)
-   - Added multi-level caching
-   - Implemented cache invalidation
-   - Added versioning system
-
-4. ~~Add batch operations for multiple changes~~ (Completed)
-   - Added BatchOperation system
-   - Implemented bulk processing
-   - Added queuing system
-
-5. ~~Implement proper cleanup for old versions~~ (Completed)
-   - Added automated cleanup
-   - Implemented archival system
-   - Added maintenance routines
-
-## Future Enhancements ✓
-1. Add visual diff viewer
-2. Implement branch locking
-3. Add commenting on changes
-4. Create change approval workflow
-5. Add version comparison tool

static/css/approval-panel.css

@@ -0,0 +1,332 @@
+/* Approval Panel Styles */
+
+.approval-panel {
+    background: #fff;
+    border: 1px solid #e5e7eb;
+    border-radius: 0.5rem;
+    overflow: hidden;
+}
+
+.approval-header {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    padding: 1rem;
+    border-bottom: 1px solid #e5e7eb;
+    background: #f9fafb;
+}
+
+.approval-title {
+    font-size: 1.125rem;
+    font-weight: 600;
+    color: #111827;
+    margin: 0;
+}
+
+.approval-status {
+    display: inline-flex;
+    align-items: center;
+    padding: 0.25rem 0.75rem;
+    border-radius: 9999px;
+    font-size: 0.875rem;
+    font-weight: 500;
+}
+
+/* Status Colors */
+.status-draft {
+    background-color: #f3f4f6;
+    color: #6b7280;
+}
+
+.status-pending {
+    background-color: #fef3c7;
+    color: #92400e;
+}
+
+.status-approved {
+    background-color: #dcfce7;
+    color: #166534;
+}
+
+.status-rejected {
+    background-color: #fee2e2;
+    color: #991b1b;
+}
+
+.status-applied {
+    background-color: #dbeafe;
+    color: #1e40af;
+}
+
+.status-failed {
+    background-color: #fee2e2;
+    color: #991b1b;
+}
+
+.status-reverted {
+    background-color: #f3f4f6;
+    color: #6b7280;
+}
+
+/* Stages */
+.approval-stages {
+    padding: 1rem;
+}
+
+.approval-stage {
+    border: 1px solid #e5e7eb;
+    border-radius: 0.375rem;
+    margin-bottom: 1rem;
+    overflow: hidden;
+}
+
+.approval-stage:last-child {
+    margin-bottom: 0;
+}
+
+.stage-header {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    padding: 0.75rem 1rem;
+    background: #f9fafb;
+    border-bottom: 1px solid #e5e7eb;
+}
+
+.stage-name {
+    font-weight: 500;
+    color: #374151;
+}
+
+.stage-status {
+    font-size: 0.875rem;
+    font-weight: 500;
+}
+
+.stage-status.pending {
+    color: #92400e;
+}
+
+.stage-status.approved {
+    color: #166534;
+}
+
+.stage-status.rejected {
+    color: #991b1b;
+}
+
+.stage-details {
+    padding: 1rem;
+}
+
+.required-roles {
+    display: flex;
+    flex-wrap: wrap;
+    gap: 0.5rem;
+    margin-bottom: 1rem;
+}
+
+.role-badge {
+    background: #f3f4f6;
+    color: #4b5563;
+    padding: 0.25rem 0.5rem;
+    border-radius: 0.25rem;
+    font-size: 0.75rem;
+    font-weight: 500;
+}
+
+/* Approvers */
+.approvers-list {
+    display: flex;
+    flex-direction: column;
+    gap: 0.75rem;
+}
+
+.approver {
+    padding: 0.75rem;
+    background: #f9fafb;
+    border-radius: 0.375rem;
+}
+
+.approver-info {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    margin-bottom: 0.5rem;
+}
+
+.approver-name {
+    font-weight: 500;
+    color: #374151;
+}
+
+.approval-date {
+    font-size: 0.75rem;
+    color: #6b7280;
+}
+
+.approver-decision {
+    font-size: 0.875rem;
+    font-weight: 500;
+    margin-bottom: 0.5rem;
+}
+
+.approver-decision.approved {
+    color: #166534;
+}
+
+.approver-decision.rejected {
+    color: #991b1b;
+}
+
+.approver-comment {
+    font-size: 0.875rem;
+    color: #4b5563;
+    padding: 0.5rem;
+    background: #fff;
+    border-radius: 0.25rem;
+}
+
+/* Approval Actions */
+.approval-actions {
+    padding: 1rem;
+    border-top: 1px solid #e5e7eb;
+    background: #f9fafb;
+}
+
+.approval-comment {
+    width: 100%;
+    min-height: 5rem;
+    padding: 0.75rem;
+    margin-bottom: 1rem;
+    border: 1px solid #d1d5db;
+    border-radius: 0.375rem;
+    resize: vertical;
+    font-size: 0.875rem;
+}
+
+.approval-comment:focus {
+    outline: none;
+    border-color: #3b82f6;
+    ring: 2px solid rgba(59, 130, 246, 0.5);
+}
+
+.action-buttons {
+    display: flex;
+    justify-content: flex-end;
+    gap: 0.75rem;
+}
+
+.approve-button,
+.reject-button {
+    padding: 0.5rem 1rem;
+    border-radius: 0.375rem;
+    font-size: 0.875rem;
+    font-weight: 500;
+    cursor: pointer;
+    transition: all 0.2s;
+}
+
+.approve-button {
+    background-color: #059669;
+    color: white;
+}
+
+.approve-button:hover {
+    background-color: #047857;
+}
+
+.reject-button {
+    background-color: #dc2626;
+    color: white;
+}
+
+.reject-button:hover {
+    background-color: #b91c1c;
+}
+
+/* History */
+.approval-history {
+    padding: 1rem;
+    border-top: 1px solid #e5e7eb;
+}
+
+.approval-history-list {
+    display: flex;
+    flex-direction: column;
+    gap: 1rem;
+}
+
+.history-entry {
+    padding: 0.75rem;
+    background: #f9fafb;
+    border-radius: 0.375rem;
+}
+
+.entry-header {
+    display: flex;
+    justify-content: space-between;
+    margin-bottom: 0.5rem;
+}
+
+.entry-user {
+    font-weight: 500;
+    color: #374151;
+}
+
+.entry-date {
+    font-size: 0.75rem;
+    color: #6b7280;
+}
+
+.entry-action {
+    font-size: 0.875rem;
+    margin-bottom: 0.5rem;
+}
+
+.entry-action.submit {
+    color: #6b7280;
+}
+
+.entry-action.approve {
+    color: #166534;
+}
+
+.entry-action.reject {
+    color: #991b1b;
+}
+
+.entry-action.revert {
+    color: #4b5563;
+}
+
+.entry-comment {
+    font-size: 0.875rem;
+    color: #4b5563;
+    padding: 0.5rem;
+    background: #fff;
+    border-radius: 0.25rem;
+}
+
+/* Responsive Design */
+@media (max-width: 640px) {
+    .approval-header {
+        flex-direction: column;
+        align-items: flex-start;
+        gap: 0.5rem;
+    }
+
+    .action-buttons {
+        flex-direction: column;
+    }
+
+    .approve-button,
+    .reject-button {
+        width: 100%;
+    }
+
+    .approver-info {
+        flex-direction: column;
+        align-items: flex-start;
+    }
+}

static/css/diff-viewer.css

@@ -0,0 +1,195 @@
+/* Diff Viewer Styles */
+
+.diff-viewer {
+    font-family: ui-monospace, monospace;
+    margin: 1rem 0;
+    border: 1px solid #e5e7eb;
+    border-radius: 0.375rem;
+    overflow: hidden;
+    background: #fff;
+}
+
+.diff-viewer.side-by-side .diff-blocks {
+    display: grid;
+    grid-template-columns: 1fr 1fr;
+    gap: 1px;
+    background: #e5e7eb;
+}
+
+.diff-header {
+    padding: 1rem;
+    border-bottom: 1px solid #e5e7eb;
+    background: #f9fafb;
+}
+
+.diff-metadata {
+    display: flex;
+    gap: 1rem;
+    font-size: 0.875rem;
+    color: #4b5563;
+}
+
+.diff-controls {
+    margin-top: 0.5rem;
+    display: flex;
+    gap: 0.5rem;
+}
+
+.diff-controls button {
+    padding: 0.25rem 0.75rem;
+    border: 1px solid #d1d5db;
+    border-radius: 0.25rem;
+    background: #fff;
+    font-size: 0.875rem;
+    color: #374151;
+    cursor: pointer;
+    transition: all 0.2s;
+}
+
+.diff-controls button:hover {
+    background: #f3f4f6;
+}
+
+.diff-section {
+    border-bottom: 1px solid #e5e7eb;
+}
+
+.diff-field-header {
+    padding: 0.5rem 1rem;
+    background: #f9fafb;
+    border-bottom: 1px solid #e5e7eb;
+    font-weight: 500;
+    cursor: pointer;
+}
+
+.diff-field-header .syntax-type {
+    font-size: 0.75rem;
+    color: #6b7280;
+    margin-left: 0.5rem;
+}
+
+.diff-block {
+    display: grid;
+    grid-template-columns: auto 1fr;
+    background: #fff;
+}
+
+.line-numbers {
+    padding: 0.5rem;
+    background: #f9fafb;
+    border-right: 1px solid #e5e7eb;
+    text-align: right;
+    color: #6b7280;
+    user-select: none;
+}
+
+.line-number {
+    display: block;
+    padding: 0 0.5rem;
+    font-size: 0.875rem;
+}
+
+.diff-block pre {
+    margin: 0;
+    padding: 0.5rem;
+    overflow-x: auto;
+}
+
+.diff-block code {
+    font-family: ui-monospace, monospace;
+    font-size: 0.875rem;
+    line-height: 1.5;
+}
+
+/* Inline diff styles */
+.diff-removed {
+    background-color: #fee2e2;
+    text-decoration: line-through;
+    color: #991b1b;
+}
+
+.diff-added {
+    background-color: #dcfce7;
+    color: #166534;
+}
+
+/* Syntax highlighting */
+.language-json .json-key {
+    color: #059669;
+}
+
+.language-python .keyword {
+    color: #7c3aed;
+}
+
+.language-python .string {
+    color: #059669;
+}
+
+.language-python .comment {
+    color: #6b7280;
+    font-style: italic;
+}
+
+/* Comment threads */
+.comment-thread {
+    border-top: 1px solid #e5e7eb;
+    padding: 1rem;
+    background: #f9fafb;
+}
+
+.comment {
+    margin-bottom: 1rem;
+    padding: 0.5rem;
+    background: #fff;
+    border: 1px solid #e5e7eb;
+    border-radius: 0.25rem;
+}
+
+.comment:last-child {
+    margin-bottom: 0;
+}
+
+.comment-header {
+    display: flex;
+    justify-content: space-between;
+    font-size: 0.75rem;
+    color: #6b7280;
+    margin-bottom: 0.25rem;
+}
+
+.comment-content {
+    font-size: 0.875rem;
+    color: #374151;
+}
+
+/* Navigation */
+.diff-navigation {
+    padding: 1rem;
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    border-top: 1px solid #e5e7eb;
+    background: #f9fafb;
+}
+
+.position-indicator {
+    font-size: 0.875rem;
+    color: #6b7280;
+}
+
+/* Collapsed state */
+.diff-section.collapsed .diff-blocks {
+    display: none;
+}
+
+/* Performance warning */
+.performance-warning {
+    padding: 0.5rem;
+    background: #fffbeb;
+    border: 1px solid #fcd34d;
+    color: #92400e;
+    font-size: 0.875rem;
+    margin: 0.5rem 1rem;
+    border-radius: 0.25rem;
+}

static/css/inline-comment-panel.css

@@ -0,0 +1,229 @@
+/* Inline Comment Panel Styles */
+
+.comment-panel {
+    background: #fff;
+    border: 1px solid #e5e7eb;
+    border-radius: 0.5rem;
+    box-shadow: 0 1px 2px rgba(0, 0, 0, 0.05);
+    margin: 1rem 0;
+}
+
+.comment-header {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    padding: 0.75rem 1rem;
+    border-bottom: 1px solid #e5e7eb;
+    background: #f9fafb;
+}
+
+.thread-info {
+    display: flex;
+    align-items: center;
+    gap: 0.75rem;
+}
+
+.anchor-info {
+    font-family: ui-monospace, monospace;
+    font-size: 0.875rem;
+    color: #4b5563;
+}
+
+.resolution-badge {
+    display: inline-flex;
+    align-items: center;
+    gap: 0.25rem;
+    padding: 0.25rem 0.5rem;
+    background: #dcfce7;
+    color: #166534;
+    border-radius: 9999px;
+    font-size: 0.75rem;
+    font-weight: 500;
+}
+
+.resolve-button {
+    padding: 0.375rem 0.75rem;
+    background: #059669;
+    color: white;
+    border-radius: 0.375rem;
+    font-size: 0.875rem;
+    font-weight: 500;
+    transition: all 0.2s;
+}
+
+.resolve-button:hover {
+    background: #047857;
+}
+
+.comments-container {
+    padding: 1rem;
+}
+
+.comment {
+    margin-bottom: 1rem;
+    padding-bottom: 1rem;
+    border-bottom: 1px solid #e5e7eb;
+}
+
+.comment:last-child {
+    margin-bottom: 0;
+    padding-bottom: 0;
+    border-bottom: none;
+}
+
+.comment.reply {
+    margin-left: 2rem;
+    padding: 0.75rem;
+    background: #f9fafb;
+    border-radius: 0.375rem;
+    border: none;
+}
+
+.comment-author {
+    display: flex;
+    align-items: center;
+    gap: 0.5rem;
+    margin-bottom: 0.5rem;
+}
+
+.author-avatar {
+    width: 2rem;
+    height: 2rem;
+    border-radius: 9999px;
+}
+
+.author-name {
+    font-weight: 500;
+    color: #111827;
+}
+
+.comment-date {
+    font-size: 0.75rem;
+    color: #6b7280;
+}
+
+.comment-content {
+    font-size: 0.875rem;
+    line-height: 1.5;
+    color: #374151;
+    margin-bottom: 0.5rem;
+}
+
+.comment-content .mention {
+    color: #2563eb;
+    font-weight: 500;
+}
+
+.comment-content a {
+    color: #2563eb;
+    text-decoration: none;
+}
+
+.comment-content a:hover {
+    text-decoration: underline;
+}
+
+.comment-actions {
+    display: flex;
+    gap: 0.75rem;
+}
+
+.action-button {
+    font-size: 0.75rem;
+    color: #6b7280;
+    background: none;
+    border: none;
+    padding: 0;
+    cursor: pointer;
+    transition: color 0.2s;
+}
+
+.action-button:hover {
+    color: #374151;
+}
+
+.reply-form {
+    padding: 1rem;
+    border-top: 1px solid #e5e7eb;
+    background: #f9fafb;
+}
+
+.reply-form.nested {
+    margin-top: 0.75rem;
+    padding: 0.75rem;
+    border: 1px solid #e5e7eb;
+    border-radius: 0.375rem;
+}
+
+.reply-input,
+.edit-input {
+    width: 100%;
+    padding: 0.5rem;
+    border: 1px solid #d1d5db;
+    border-radius: 0.375rem;
+    font-size: 0.875rem;
+    resize: vertical;
+    margin-bottom: 0.5rem;
+}
+
+.reply-input:focus,
+.edit-input:focus {
+    outline: none;
+    border-color: #3b82f6;
+    ring: 2px solid rgba(59, 130, 246, 0.5);
+}
+
+.form-actions {
+    display: flex;
+    justify-content: flex-end;
+    gap: 0.5rem;
+}
+
+.reply-button,
+.save-button {
+    padding: 0.375rem 0.75rem;
+    background: #3b82f6;
+    color: white;
+    border-radius: 0.375rem;
+    font-size: 0.875rem;
+    font-weight: 500;
+    transition: all 0.2s;
+}
+
+.reply-button:hover,
+.save-button:hover {
+    background: #2563eb;
+}
+
+.cancel-button {
+    padding: 0.375rem 0.75rem;
+    background: #fff;
+    color: #4b5563;
+    border: 1px solid #d1d5db;
+    border-radius: 0.375rem;
+    font-size: 0.875rem;
+    font-weight: 500;
+    transition: all 0.2s;
+}
+
+.cancel-button:hover {
+    background: #f3f4f6;
+}
+
+/* Responsive Design */
+@media (max-width: 640px) {
+    .comment.reply {
+        margin-left: 1rem;
+    }
+
+    .comment-header {
+        flex-direction: column;
+        align-items: flex-start;
+        gap: 0.5rem;
+    }
+
+    .resolve-button {
+        width: 100%;
+        text-align: center;
+    }
+}

static/css/version-comparison.css

@@ -0,0 +1,353 @@
+/* Version Comparison Tool Styles */
+
+.version-comparison-tool {
+    background: #fff;
+    border: 1px solid #e5e7eb;
+    border-radius: 0.5rem;
+    overflow: hidden;
+}
+
+/* Header Styles */
+.comparison-header {
+    padding: 1rem;
+    border-bottom: 1px solid #e5e7eb;
+    background: #f9fafb;
+}
+
+.comparison-header h3 {
+    margin: 0 0 1rem 0;
+    font-size: 1.125rem;
+    font-weight: 600;
+    color: #111827;
+}
+
+.selected-versions {
+    display: flex;
+    flex-wrap: wrap;
+    gap: 0.5rem;
+    margin-bottom: 1rem;
+}
+
+.selected-version {
+    display: flex;
+    align-items: center;
+    gap: 0.5rem;
+    padding: 0.375rem 0.75rem;
+    background: #f3f4f6;
+    border-radius: 0.375rem;
+    font-size: 0.875rem;
+}
+
+.version-label {
+    font-weight: 500;
+    color: #374151;
+}
+
+.version-value {
+    color: #4b5563;
+}
+
+.remove-version {
+    border: none;
+    background: none;
+    color: #6b7280;
+    cursor: pointer;
+    padding: 0.125rem 0.25rem;
+    font-size: 1rem;
+    line-height: 1;
+}
+
+.remove-version:hover {
+    color: #ef4444;
+}
+
+/* Timeline Styles */
+.version-timeline {
+    position: relative;
+    padding: 2rem 1rem;
+    overflow-x: auto;
+    cursor: grab;
+    user-select: none;
+}
+
+.version-timeline.active {
+    cursor: grabbing;
+}
+
+.timeline-track {
+    position: relative;
+    height: 2px;
+    background: #e5e7eb;
+    margin: 0 2rem;
+}
+
+.timeline-point {
+    position: absolute;
+    top: 50%;
+    transform: translate(-50%, -50%);
+    cursor: pointer;
+}
+
+.timeline-point::before {
+    content: '';
+    position: absolute;
+    top: 50%;
+    left: 50%;
+    transform: translate(-50%, -50%);
+    width: 12px;
+    height: 12px;
+    background: #fff;
+    border: 2px solid #6b7280;
+    border-radius: 50%;
+    transition: all 0.2s;
+}
+
+.timeline-point.selected::before {
+    background: #3b82f6;
+    border-color: #3b82f6;
+}
+
+.impact-indicator {
+    position: absolute;
+    top: -24px;
+    left: 50%;
+    transform: translateX(-50%);
+    border-radius: 50%;
+    background: rgba(59, 130, 246, 0.1);
+    border: 2px solid rgba(59, 130, 246, 0.2);
+    transition: all 0.2s;
+}
+
+.timeline-labels {
+    display: flex;
+    position: absolute;
+    bottom: 0.5rem;
+    left: 0;
+    right: 0;
+    padding: 0 2rem;
+}
+
+.timeline-label {
+    position: absolute;
+    transform: translateX(-50%);
+    text-align: center;
+    min-width: 100px;
+}
+
+.version-name {
+    font-weight: 500;
+    font-size: 0.875rem;
+    color: #374151;
+    margin-bottom: 0.25rem;
+}
+
+.version-date {
+    font-size: 0.75rem;
+    color: #6b7280;
+}
+
+/* Comparison Actions */
+.comparison-actions {
+    display: flex;
+    gap: 0.75rem;
+}
+
+.compare-button,
+.rollback-button {
+    padding: 0.5rem 1rem;
+    border-radius: 0.375rem;
+    font-size: 0.875rem;
+    font-weight: 500;
+    cursor: pointer;
+    transition: all 0.2s;
+}
+
+.compare-button {
+    background-color: #3b82f6;
+    color: white;
+}
+
+.compare-button:hover {
+    background-color: #2563eb;
+}
+
+.rollback-button {
+    background-color: #6b7280;
+    color: white;
+}
+
+.rollback-button:hover {
+    background-color: #4b5563;
+}
+
+/* Comparison Results */
+.comparison-content {
+    padding: 1rem;
+}
+
+.comparison-placeholder {
+    text-align: center;
+    padding: 2rem;
+    color: #6b7280;
+    font-size: 0.875rem;
+}
+
+.results-loading {
+    text-align: center;
+    padding: 2rem;
+    color: #6b7280;
+}
+
+.diff-section {
+    border: 1px solid #e5e7eb;
+    border-radius: 0.375rem;
+    margin-bottom: 1rem;
+    overflow: hidden;
+}
+
+.diff-header {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+    padding: 0.75rem 1rem;
+    background: #f9fafb;
+    border-bottom: 1px solid #e5e7eb;
+}
+
+.diff-header h4 {
+    margin: 0;
+    font-size: 0.875rem;
+    font-weight: 600;
+    color: #374151;
+}
+
+.diff-stats {
+    display: flex;
+    gap: 1rem;
+    font-size: 0.75rem;
+    color: #6b7280;
+}
+
+.change-item {
+    padding: 1rem;
+    border-bottom: 1px solid #e5e7eb;
+}
+
+.change-item:last-child {
+    border-bottom: none;
+}
+
+.change-header {
+    display: flex;
+    align-items: center;
+    gap: 0.5rem;
+    margin-bottom: 0.75rem;
+}
+
+.change-type {
+    padding: 0.25rem 0.5rem;
+    background: #f3f4f6;
+    border-radius: 0.25rem;
+    font-size: 0.75rem;
+    font-weight: 500;
+    color: #374151;
+}
+
+.change-file {
+    font-family: ui-monospace, monospace;
+    font-size: 0.875rem;
+    color: #4b5563;
+}
+
+.change-content {
+    display: grid;
+    grid-template-columns: repeat(2, 1fr);
+    gap: 1rem;
+}
+
+.old-value,
+.new-value {
+    background: #f9fafb;
+    border-radius: 0.375rem;
+    overflow: hidden;
+}
+
+.value-header {
+    padding: 0.5rem;
+    background: #f3f4f6;
+    font-size: 0.75rem;
+    font-weight: 500;
+    color: #4b5563;
+    border-bottom: 1px solid #e5e7eb;
+}
+
+.change-content pre {
+    margin: 0;
+    padding: 0.75rem;
+    font-size: 0.875rem;
+    line-height: 1.5;
+    overflow-x: auto;
+}
+
+/* Warning/Error Messages */
+.comparison-warning,
+.comparison-error {
+    position: fixed;
+    top: 1rem;
+    right: 1rem;
+    padding: 0.75rem 1rem;
+    border-radius: 0.375rem;
+    font-size: 0.875rem;
+    animation: slideIn 0.3s ease-out;
+}
+
+.comparison-warning {
+    background: #fef3c7;
+    color: #92400e;
+    border: 1px solid #f59e0b;
+}
+
+.comparison-error {
+    background: #fee2e2;
+    color: #991b1b;
+    border: 1px solid #ef4444;
+}
+
+@keyframes slideIn {
+    from {
+        transform: translateX(100%);
+        opacity: 0;
+    }
+    to {
+        transform: translateX(0);
+        opacity: 1;
+    }
+}
+
+/* Responsive Design */
+@media (max-width: 768px) {
+    .comparison-header {
+        padding: 0.75rem;
+    }
+
+    .selected-versions {
+        flex-direction: column;
+    }
+
+    .comparison-actions {
+        flex-direction: column;
+    }
+
+    .compare-button,
+    .rollback-button {
+        width: 100%;
+    }
+
+    .change-content {
+        grid-template-columns: 1fr;
+    }
+
+    .timeline-label {
+        min-width: 80px;
+    }
+}

static/css/version-control.css

@@ -142,6 +142,115 @@
     margin: 0.25rem;
 }
 
+/* Branch Lock Status */
+.lock-status {
+    display: inline-flex;
+    align-items: center;
+    gap: 0.5rem;
+    padding: 0.25rem 0.75rem;
+    border-radius: 0.375rem;
+    font-size: 0.875rem;
+    margin-left: 0.5rem;
+}
+
+.lock-status.locked {
+    background-color: rgba(239, 68, 68, 0.1);
+    color: var(--vcs-error);
+}
+
+.lock-status.unlocked {
+    background-color: rgba(16, 185, 129, 0.1);
+    color: var(--vcs-success);
+}
+
+.lock-status .lock-icon {
+    width: 1rem;
+    height: 1rem;
+}
+
+.lock-info {
+    display: flex;
+    flex-direction: column;
+    font-size: 0.75rem;
+    color: var(--vcs-gray);
+}
+
+.lock-info .user {
+    font-weight: 500;
+    color: inherit;
+}
+
+.lock-info .expiry {
+    opacity: 0.8;
+}
+
+/* Lock Controls */
+.lock-controls {
+    display: flex;
+    gap: 0.5rem;
+    margin-top: 0.5rem;
+}
+
+.lock-button {
+    display: inline-flex;
+    align-items: center;
+    gap: 0.25rem;
+    padding: 0.375rem 0.75rem;
+    border-radius: 0.375rem;
+    font-size: 0.875rem;
+    font-weight: 500;
+    cursor: pointer;
+    transition: all 0.2s;
+}
+
+.lock-button.lock {
+    background-color: var(--vcs-error);
+    color: white;
+}
+
+.lock-button.unlock {
+    background-color: var(--vcs-success);
+    color: white;
+}
+
+.lock-button:hover {
+    opacity: 0.9;
+}
+
+.lock-button:disabled {
+    opacity: 0.5;
+    cursor: not-allowed;
+}
+
+/* Lock History */
+.lock-history {
+    margin-top: 1rem;
+    border-top: 1px solid #e5e7eb;
+    padding-top: 1rem;
+}
+
+.lock-history-item {
+    display: flex;
+    align-items: flex-start;
+    gap: 1rem;
+    padding: 0.5rem 0;
+    font-size: 0.875rem;
+}
+
+.lock-history-item .action {
+    font-weight: 500;
+}
+
+.lock-history-item .timestamp {
+    color: var(--vcs-gray);
+}
+
+.lock-history-item .reason {
+    margin-top: 0.25rem;
+    color: var(--vcs-gray);
+    font-style: italic;
+}
+
 /* Loading States */
 .vcs-loading {
     position: relative;

static/js/collaboration-system.js

@@ -0,0 +1,203 @@
+// Collaboration System
+
+class CollaborationSystem {
+    constructor(options = {}) {
+        this.onCommentAdded = options.onCommentAdded || (() => {});
+        this.onCommentResolved = options.onCommentResolved || (() => {});
+        this.onThreadCreated = options.onThreadCreated || (() => {});
+        this.socket = null;
+        this.currentUser = options.currentUser;
+    }
+
+    initialize(socketUrl) {
+        this.socket = new WebSocket(socketUrl);
+        this.setupSocketHandlers();
+    }
+
+    setupSocketHandlers() {
+        if (!this.socket) return;
+
+        this.socket.addEventListener('open', () => {
+            console.log('Collaboration system connected');
+        });
+
+        this.socket.addEventListener('message', (event) => {
+            try {
+                const data = JSON.parse(event.data);
+                this.handleEvent(data);
+            } catch (error) {
+                console.error('Failed to parse collaboration event:', error);
+            }
+        });
+
+        this.socket.addEventListener('close', () => {
+            console.log('Collaboration system disconnected');
+            // Attempt to reconnect after delay
+            setTimeout(() => this.reconnect(), 5000);
+        });
+
+        this.socket.addEventListener('error', (error) => {
+            console.error('Collaboration system error:', error);
+        });
+    }
+
+    handleEvent(event) {
+        switch (event.type) {
+            case 'comment_added':
+                this.onCommentAdded(event.data);
+                break;
+            case 'comment_resolved':
+                this.onCommentResolved(event.data);
+                break;
+            case 'thread_created':
+                this.onThreadCreated(event.data);
+                break;
+            default:
+                console.warn('Unknown collaboration event:', event.type);
+        }
+    }
+
+    async createCommentThread(changeId, anchor, initialComment) {
+        try {
+            const response = await fetch('/vcs/comments/threads/create/', {
+                method: 'POST',
+                headers: {
+                    'Content-Type': 'application/json',
+                    'X-CSRFToken': this.getCsrfToken()
+                },
+                body: JSON.stringify({
+                    change_id: changeId,
+                    anchor: anchor,
+                    initial_comment: initialComment
+                })
+            });
+
+            if (!response.ok) {
+                throw new Error('Failed to create comment thread');
+            }
+
+            const thread = await response.json();
+            
+            // Notify other users through WebSocket
+            this.broadcastEvent({
+                type: 'thread_created',
+                data: {
+                    thread_id: thread.id,
+                    change_id: changeId,
+                    anchor: anchor,
+                    author: this.currentUser,
+                    timestamp: new Date().toISOString()
+                }
+            });
+
+            return thread;
+        } catch (error) {
+            console.error('Error creating comment thread:', error);
+            throw error;
+        }
+    }
+
+    async addComment(threadId, content, parentId = null) {
+        try {
+            const response = await fetch('/vcs/comments/create/', {
+                method: 'POST',
+                headers: {
+                    'Content-Type': 'application/json',
+                    'X-CSRFToken': this.getCsrfToken()
+                },
+                body: JSON.stringify({
+                    thread_id: threadId,
+                    content: content,
+                    parent_id: parentId
+                })
+            });
+
+            if (!response.ok) {
+                throw new Error('Failed to add comment');
+            }
+
+            const comment = await response.json();
+            
+            // Notify other users through WebSocket
+            this.broadcastEvent({
+                type: 'comment_added',
+                data: {
+                    comment_id: comment.id,
+                    thread_id: threadId,
+                    parent_id: parentId,
+                    author: this.currentUser,
+                    content: content,
+                    timestamp: new Date().toISOString()
+                }
+            });
+
+            return comment;
+        } catch (error) {
+            console.error('Error adding comment:', error);
+            throw error;
+        }
+    }
+
+    async resolveThread(threadId) {
+        try {
+            const response = await fetch(`/vcs/comments/threads/${threadId}/resolve/`, {
+                method: 'POST',
+                headers: {
+                    'Content-Type': 'application/json',
+                    'X-CSRFToken': this.getCsrfToken()
+                }
+            });
+
+            if (!response.ok) {
+                throw new Error('Failed to resolve thread');
+            }
+
+            const result = await response.json();
+            
+            // Notify other users through WebSocket
+            this.broadcastEvent({
+                type: 'comment_resolved',
+                data: {
+                    thread_id: threadId,
+                    resolver: this.currentUser,
+                    timestamp: new Date().toISOString()
+                }
+            });
+
+            return result;
+        } catch (error) {
+            console.error('Error resolving thread:', error);
+            throw error;
+        }
+    }
+
+    broadcastEvent(event) {
+        if (this.socket && this.socket.readyState === WebSocket.OPEN) {
+            this.socket.send(JSON.stringify(event));
+        }
+    }
+
+    reconnect() {
+        if (this.socket) {
+            try {
+                this.socket.close();
+            } catch (error) {
+                console.error('Error closing socket:', error);
+            }
+        }
+        this.initialize(this.socketUrl);
+    }
+
+    getCsrfToken() {
+        return document.querySelector('[name=csrfmiddlewaretoken]').value;
+    }
+
+    disconnect() {
+        if (this.socket) {
+            this.socket.close();
+            this.socket = null;
+        }
+    }
+}
+
+export default CollaborationSystem;

static/js/components/approval-panel.js

@@ -0,0 +1,234 @@
+// Approval Panel Component
+
+class ApprovalPanel {
+    constructor(options = {}) {
+        this.container = null;
+        this.changeset = null;
+        this.currentUser = options.currentUser;
+        this.onApprove = options.onApprove || (() => {});
+        this.onReject = options.onReject || (() => {});
+        this.onSubmit = options.onSubmit || (() => {});
+    }
+
+    initialize(containerId) {
+        this.container = document.getElementById(containerId);
+        if (!this.container) {
+            throw new Error(`Container element with id "${containerId}" not found`);
+        }
+    }
+
+    setChangeset(changeset) {
+        this.changeset = changeset;
+        this.render();
+    }
+
+    render() {
+        if (!this.container || !this.changeset) return;
+
+        const approvalState = this.changeset.approval_state || [];
+        const currentStage = approvalState.find(s => s.status === 'pending') || approvalState[0];
+
+        this.container.innerHTML = `
+            <div class="approval-panel">
+                <div class="approval-header">
+                    <h3 class="approval-title">Change Approval</h3>
+                    ${this._renderStatus()}
+                </div>
+                
+                <div class="approval-stages">
+                    ${this._renderStages(approvalState)}
+                </div>
+
+                ${currentStage && this.changeset.status === 'pending_approval' ?
+                    this._renderApprovalActions(currentStage) : ''
+                }
+
+                <div class="approval-history">
+                    ${this._renderHistory()}
+                </div>
+            </div>
+        `;
+
+        this.attachEventListeners();
+    }
+
+    _renderStatus() {
+        const statusMap = {
+            'draft': { class: 'status-draft', text: 'Draft' },
+            'pending_approval': { class: 'status-pending', text: 'Pending Approval' },
+            'approved': { class: 'status-approved', text: 'Approved' },
+            'rejected': { class: 'status-rejected', text: 'Rejected' },
+            'applied': { class: 'status-applied', text: 'Applied' },
+            'failed': { class: 'status-failed', text: 'Failed' },
+            'reverted': { class: 'status-reverted', text: 'Reverted' }
+        };
+
+        const status = statusMap[this.changeset.status] || statusMap.draft;
+        return `
+            <div class="approval-status ${status.class}">
+                ${status.text}
+            </div>
+        `;
+    }
+
+    _renderStages(stages) {
+        return stages.map((stage, index) => `
+            <div class="approval-stage ${stage.status}-stage">
+                <div class="stage-header">
+                    <span class="stage-name">${stage.name}</span>
+                    <span class="stage-status ${stage.status}">${
+                        this._formatStageStatus(stage.status)
+                    }</span>
+                </div>
+                <div class="stage-details">
+                    <div class="required-roles">
+                        ${stage.required_roles.map(role => `
+                            <span class="role-badge">${role}</span>
+                        `).join('')}
+                    </div>
+                    ${stage.approvers.length > 0 ? `
+                        <div class="approvers-list">
+                            ${stage.approvers.map(approver => this._renderApprover(approver)).join('')}
+                        </div>
+                    ` : ''}
+                </div>
+            </div>
+        `).join('');
+    }
+
+    _renderApprover(approver) {
+        const decisionClass = approver.decision === 'approve' ? 'approved' : 'rejected';
+        return `
+            <div class="approver">
+                <div class="approver-info">
+                    <span class="approver-name">${approver.username}</span>
+                    <span class="approval-date">
+                        ${new Date(approver.timestamp).toLocaleString()}
+                    </span>
+                </div>
+                <div class="approver-decision ${decisionClass}">
+                    ${approver.decision === 'approve' ? 'Approved' : 'Rejected'}
+                </div>
+                ${approver.comment ? `
+                    <div class="approver-comment">${approver.comment}</div>
+                ` : ''}
+            </div>
+        `;
+    }
+
+    _renderApprovalActions(currentStage) {
+        if (!this.canUserApprove(currentStage)) {
+            return '';
+        }
+
+        return `
+            <div class="approval-actions">
+                <textarea 
+                    class="approval-comment" 
+                    placeholder="Add your comments (optional)"
+                ></textarea>
+                <div class="action-buttons">
+                    <button class="reject-button" onclick="this.handleReject()">
+                        Reject Changes
+                    </button>
+                    <button class="approve-button" onclick="this.handleApprove()">
+                        Approve Changes
+                    </button>
+                </div>
+            </div>
+        `;
+    }
+
+    _renderHistory() {
+        if (!this.changeset.approval_history?.length) {
+            return '';
+        }
+
+        return `
+            <div class="approval-history-list">
+                ${this.changeset.approval_history.map(entry => `
+                    <div class="history-entry">
+                        <div class="entry-header">
+                            <span class="entry-user">${entry.username}</span>
+                            <span class="entry-date">
+                                ${new Date(entry.timestamp).toLocaleString()}
+                            </span>
+                        </div>
+                        <div class="entry-action ${entry.action}">
+                            ${this._formatHistoryAction(entry.action)}
+                        </div>
+                        ${entry.comment ? `
+                            <div class="entry-comment">${entry.comment}</div>
+                        ` : ''}
+                    </div>
+                `).join('')}
+            </div>
+        `;
+    }
+
+    _formatStageStatus(status) {
+        const statusMap = {
+            'pending': 'Pending',
+            'approved': 'Approved',
+            'rejected': 'Rejected'
+        };
+        return statusMap[status] || status;
+    }
+
+    _formatHistoryAction(action) {
+        const actionMap = {
+            'submit': 'Submitted for approval',
+            'approve': 'Approved changes',
+            'reject': 'Rejected changes',
+            'revert': 'Reverted approval'
+        };
+        return actionMap[action] || action;
+    }
+
+    canUserApprove(stage) {
+        if (!this.currentUser) return false;
+
+        // Check if user already approved
+        const alreadyApproved = stage.approvers.some(
+            a => a.user_id === this.currentUser.id
+        );
+        if (alreadyApproved) return false;
+
+        // Check if user has required role
+        return stage.required_roles.some(
+            role => this.currentUser.roles.includes(role)
+        );
+    }
+
+    async handleApprove() {
+        const commentEl = this.container.querySelector('.approval-comment');
+        const comment = commentEl ? commentEl.value.trim() : '';
+
+        try {
+            await this.onApprove(comment);
+            this.render();
+        } catch (error) {
+            console.error('Failed to approve:', error);
+            // Show error message
+        }
+    }
+
+    async handleReject() {
+        const commentEl = this.container.querySelector('.approval-comment');
+        const comment = commentEl ? commentEl.value.trim() : '';
+
+        try {
+            await this.onReject(comment);
+            this.render();
+        } catch (error) {
+            console.error('Failed to reject:', error);
+            // Show error message
+        }
+    }
+
+    attachEventListeners() {
+        // Add any additional event listeners if needed
+    }
+}
+
+export default ApprovalPanel;

static/js/components/diff-viewer.js

@@ -0,0 +1,274 @@
+// Enhanced Diff Viewer Component
+
+class DiffViewer {
+    constructor(options = {}) {
+        this.renderStrategy = options.renderStrategy || 'side-by-side';
+        this.syntaxHighlighters = new Map();
+        this.commentThreads = [];
+        this.container = null;
+        this.performance = {
+            startTime: null,
+            endTime: null
+        };
+    }
+
+    initialize(containerId) {
+        this.container = document.getElementById(containerId);
+        if (!this.container) {
+            throw new Error(`Container element with id "${containerId}" not found`);
+        }
+        this.setupSyntaxHighlighters();
+    }
+
+    setupSyntaxHighlighters() {
+        // Set up Prism.js or similar syntax highlighting library
+        this.syntaxHighlighters.set('text', this.plainTextHighlighter);
+        this.syntaxHighlighters.set('json', this.jsonHighlighter);
+        this.syntaxHighlighters.set('python', this.pythonHighlighter);
+    }
+
+    async render(diffData) {
+        this.performance.startTime = performance.now();
+
+        const { changes, metadata, navigation } = diffData;
+        const content = this.renderStrategy === 'side-by-side' 
+            ? this.renderSideBySide(changes)
+            : this.renderInline(changes);
+
+        this.container.innerHTML = `
+            <div class="diff-viewer ${this.renderStrategy}">
+                <div class="diff-header">
+                    ${this.renderMetadata(metadata)}
+                    ${this.renderControls()}
+                </div>
+                <div class="diff-content">
+                    ${content}
+                </div>
+                ${this.renderNavigation(navigation)}
+            </div>
+        `;
+
+        this.attachEventListeners();
+        await this.highlightSyntax();
+        
+        this.performance.endTime = performance.now();
+        this.updatePerformanceMetrics();
+    }
+
+    renderSideBySide(changes) {
+        return Object.entries(changes).map(([field, change]) => `
+            <div class="diff-section" data-field="${field}">
+                <div class="diff-field-header">
+                    <span class="field-name">${field}</span>
+                    <span class="syntax-type">${change.syntax_type}</span>
+                </div>
+                <div class="diff-blocks">
+                    <div class="diff-block old" data-anchor="${change.metadata.comment_anchor_id}-old">
+                        <div class="line-numbers">
+                            ${this.renderLineNumbers(change.metadata.line_numbers.old)}
+                        </div>
+                        <pre><code class="language-${change.syntax_type}">${this.escapeHtml(change.old)}</code></pre>
+                    </div>
+                    <div class="diff-block new" data-anchor="${change.metadata.comment_anchor_id}-new">
+                        <div class="line-numbers">
+                            ${this.renderLineNumbers(change.metadata.line_numbers.new)}
+                        </div>
+                        <pre><code class="language-${change.syntax_type}">${this.escapeHtml(change.new)}</code></pre>
+                    </div>
+                </div>
+            </div>
+        `).join('');
+    }
+
+    renderInline(changes) {
+        return Object.entries(changes).map(([field, change]) => `
+            <div class="diff-section" data-field="${field}">
+                <div class="diff-field-header">
+                    <span class="field-name">${field}</span>
+                    <span class="syntax-type">${change.syntax_type}</span>
+                </div>
+                <div class="diff-block inline" data-anchor="${change.metadata.comment_anchor_id}">
+                    <div class="line-numbers">
+                        ${this.renderLineNumbers(change.metadata.line_numbers.new)}
+                    </div>
+                    <pre><code class="language-${change.syntax_type}">
+                        ${this.renderInlineDiff(change.old, change.new)}
+                    </code></pre>
+                </div>
+            </div>
+        `).join('');
+    }
+
+    renderMetadata(metadata) {
+        return `
+            <div class="diff-metadata">
+                <span class="timestamp">${new Date(metadata.timestamp).toLocaleString()}</span>
+                <span class="user">${metadata.user || 'Anonymous'}</span>
+                <span class="change-type">${this.formatChangeType(metadata.change_type)}</span>
+                ${metadata.reason ? `<span class="reason">${metadata.reason}</span>` : ''}
+            </div>
+        `;
+    }
+
+    renderControls() {
+        return `
+            <div class="diff-controls">
+                <button class="btn-view-mode" data-mode="side-by-side">Side by Side</button>
+                <button class="btn-view-mode" data-mode="inline">Inline</button>
+                <button class="btn-collapse-all">Collapse All</button>
+                <button class="btn-expand-all">Expand All</button>
+            </div>
+        `;
+    }
+
+    renderNavigation(navigation) {
+        return `
+            <div class="diff-navigation">
+                ${navigation.prev_id ? `<button class="btn-prev" data-id="${navigation.prev_id}">Previous</button>` : ''}
+                ${navigation.next_id ? `<button class="btn-next" data-id="${navigation.next_id}">Next</button>` : ''}
+                <span class="position-indicator">Change ${navigation.current_position}</span>
+            </div>
+        `;
+    }
+
+    renderLineNumbers(numbers) {
+        return numbers.map(num => `<span class="line-number">${num}</span>`).join('');
+    }
+
+    renderInlineDiff(oldText, newText) {
+        // Simple inline diff implementation - could be enhanced with more sophisticated diff algorithm
+        const oldLines = oldText.split('\n');
+        const newLines = newText.split('\n');
+        const diffLines = [];
+
+        for (let i = 0; i < Math.max(oldLines.length, newLines.length); i++) {
+            if (oldLines[i] !== newLines[i]) {
+                if (oldLines[i]) {
+                    diffLines.push(`<span class="diff-removed">${this.escapeHtml(oldLines[i])}</span>`);
+                }
+                if (newLines[i]) {
+                    diffLines.push(`<span class="diff-added">${this.escapeHtml(newLines[i])}</span>`);
+                }
+            } else if (oldLines[i]) {
+                diffLines.push(this.escapeHtml(oldLines[i]));
+            }
+        }
+
+        return diffLines.join('\n');
+    }
+
+    attachEventListeners() {
+        // View mode switching
+        this.container.querySelectorAll('.btn-view-mode').forEach(btn => {
+            btn.addEventListener('click', () => {
+                this.renderStrategy = btn.dataset.mode;
+                this.render(this.currentDiffData);
+            });
+        });
+
+        // Collapse/Expand functionality
+        this.container.querySelectorAll('.diff-section').forEach(section => {
+            section.querySelector('.diff-field-header').addEventListener('click', () => {
+                section.classList.toggle('collapsed');
+            });
+        });
+
+        // Navigation
+        this.container.querySelectorAll('.diff-navigation button').forEach(btn => {
+            btn.addEventListener('click', () => {
+                this.navigateToChange(btn.dataset.id);
+            });
+        });
+    }
+
+    async highlightSyntax() {
+        const codeBlocks = this.container.querySelectorAll('code[class^="language-"]');
+        for (const block of codeBlocks) {
+            const syntax = block.className.replace('language-', '');
+            const highlighter = this.syntaxHighlighters.get(syntax);
+            if (highlighter) {
+                await highlighter(block);
+            }
+        }
+    }
+
+    // Syntax highlighters
+    async plainTextHighlighter(element) {
+        // No highlighting needed for plain text
+        return element;
+    }
+
+    async jsonHighlighter(element) {
+        try {
+            const content = element.textContent;
+            const parsed = JSON.parse(content);
+            element.textContent = JSON.stringify(parsed, null, 2);
+            // Apply JSON syntax highlighting classes
+            element.innerHTML = element.innerHTML.replace(
+                /"([^"]+)":/g,
+                '<span class="json-key">"$1":</span>'
+            );
+        } catch (e) {
+            console.warn('JSON parsing failed:', e);
+        }
+        return element;
+    }
+
+    async pythonHighlighter(element) {
+        // Basic Python syntax highlighting
+        element.innerHTML = element.innerHTML
+            .replace(/(def|class|import|from|return|if|else|try|except)\b/g, '<span class="keyword">$1</span>')
+            .replace(/(["'])(.*?)\1/g, '<span class="string">$1$2$1</span>')
+            .replace(/#.*/g, '<span class="comment">$&</span>');
+        return element;
+    }
+
+    updatePerformanceMetrics() {
+        const renderTime = this.performance.endTime - this.performance.startTime;
+        if (renderTime > 200) { // Performance budget: 200ms
+            console.warn(`Diff render time (${renderTime}ms) exceeded performance budget`);
+        }
+    }
+
+    escapeHtml(text) {
+        const div = document.createElement('div');
+        div.textContent = text;
+        return div.innerHTML;
+    }
+
+    formatChangeType(type) {
+        const types = {
+            'C': 'Changed',
+            'D': 'Deleted',
+            'A': 'Added'
+        };
+        return types[type] || type;
+    }
+
+    addCommentThread(anchor, thread) {
+        this.commentThreads.push({ anchor, thread });
+        this.renderCommentThreads();
+    }
+
+    renderCommentThreads() {
+        this.commentThreads.forEach(({ anchor, thread }) => {
+            const element = this.container.querySelector(`[data-anchor="${anchor}"]`);
+            if (element) {
+                const threadElement = document.createElement('div');
+                threadElement.className = 'comment-thread';
+                threadElement.innerHTML = thread.map(comment => `
+                    <div class="comment">
+                        <div class="comment-header">
+                            <span class="comment-author">${comment.author}</span>
+                            <span class="comment-date">${new Date(comment.date).toLocaleString()}</span>
+                        </div>
+                        <div class="comment-content">${comment.content}</div>
+                    </div>
+                `).join('');
+                element.appendChild(threadElement);
+            }
+        });
+    }
+}
+
+export default DiffViewer;

static/js/components/inline-comment-panel.js

@@ -0,0 +1,285 @@
+// Inline Comment Panel Component
+
+class InlineCommentPanel {
+    constructor(options = {}) {
+        this.container = null;
+        this.thread = null;
+        this.canResolve = options.canResolve || false;
+        this.onReply = options.onReply || (() => {});
+        this.onResolve = options.onResolve || (() => {});
+        this.currentUser = options.currentUser;
+    }
+
+    initialize(containerId) {
+        this.container = document.getElementById(containerId);
+        if (!this.container) {
+            throw new Error(`Container element with id "${containerId}" not found`);
+        }
+    }
+
+    setThread(thread) {
+        this.thread = thread;
+        this.render();
+    }
+
+    render() {
+        if (!this.container || !this.thread) return;
+
+        this.container.innerHTML = `
+            <div class="comment-panel">
+                <div class="comment-header">
+                    <div class="thread-info">
+                        <span class="anchor-info">${this.formatAnchor(this.thread.anchor)}</span>
+                        ${this.thread.is_resolved ? 
+                            `<span class="resolution-badge">
+                                <svg class="w-4 h-4" viewBox="0 0 20 20" fill="currentColor">
+                                    <path fill-rule="evenodd" d="M16.707 5.293a1 1 0 010 1.414l-8 8a1 1 0 01-1.414 0l-4-4a1 1 0 011.414-1.414L8 12.586l7.293-7.293a1 1 0 011.414 0z" clip-rule="evenodd"/>
+                                </svg>
+                                Resolved
+                            </span>`
+                            : ''
+                        }
+                    </div>
+                    ${this.canResolve && !this.thread.is_resolved ?
+                        `<button class="resolve-button" onclick="this.resolveThread()">
+                            Resolve Thread
+                        </button>`
+                        : ''
+                    }
+                </div>
+                <div class="comments-container">
+                    ${this.renderComments(this.thread.comments)}
+                </div>
+                ${!this.thread.is_resolved ?
+                    `<div class="reply-form">
+                        <textarea
+                            class="reply-input"
+                            placeholder="Write a reply..."
+                            rows="2"
+                        ></textarea>
+                        <div class="form-actions">
+                            <button class="reply-button" onclick="this.submitReply()">
+                                Reply
+                            </button>
+                        </div>
+                    </div>`
+                    : ''
+                }
+            </div>
+        `;
+
+        this.attachEventListeners();
+    }
+
+    renderComments(comments) {
+        return comments.map(comment => `
+            <div class="comment ${comment.parent_comment ? 'reply' : ''}" data-comment-id="${comment.id}">
+                <div class="comment-author">
+                    <img src="${comment.author.avatar_url || '/static/images/default-avatar.png'}" 
+                         alt="${comment.author.username}"
+                         class="author-avatar"
+                    />
+                    <span class="author-name">${comment.author.username}</span>
+                    <span class="comment-date">${this.formatDate(comment.created_at)}</span>
+                </div>
+                <div class="comment-content">
+                    ${this.formatCommentContent(comment.content)}
+                </div>
+                ${this.renderCommentActions(comment)}
+                ${comment.replies ? 
+                    `<div class="replies">
+                        ${this.renderComments(comment.replies)}
+                    </div>`
+                    : ''
+                }
+            </div>
+        `).join('');
+    }
+
+    renderCommentActions(comment) {
+        if (this.thread.is_resolved) return '';
+
+        return `
+            <div class="comment-actions">
+                <button class="action-button" onclick="this.showReplyForm('${comment.id}')">
+                    Reply
+                </button>
+                ${comment.author.id === this.currentUser.id ?
+                    `<button class="action-button" onclick="this.editComment('${comment.id}')">
+                        Edit
+                    </button>`
+                    : ''
+                }
+            </div>
+        `;
+    }
+
+    formatCommentContent(content) {
+        // Replace @mentions with styled spans
+        content = content.replace(/@(\w+)/g, '<span class="mention">@$1</span>');
+        
+        // Convert URLs to links
+        content = content.replace(
+            /(https?:\/\/[^\s<]+[^<.,:;"')\]\s])/g,
+            '<a href="$1" target="_blank" rel="noopener noreferrer">$1</a>'
+        );
+
+        return content;
+    }
+
+    formatAnchor(anchor) {
+        const start = anchor.line_start;
+        const end = anchor.line_end;
+        const file = anchor.file_path.split('/').pop();
+
+        return end > start ?
+            `${file}:${start}-${end}` :
+            `${file}:${start}`;
+    }
+
+    formatDate(dateString) {
+        const date = new Date(dateString);
+        return date.toLocaleString();
+    }
+
+    attachEventListeners() {
+        const replyInput = this.container.querySelector('.reply-input');
+        if (replyInput) {
+            replyInput.addEventListener('keydown', (e) => {
+                if (e.key === 'Enter' && (e.metaKey || e.ctrlKey)) {
+                    this.submitReply();
+                }
+            });
+        }
+    }
+
+    async submitReply() {
+        const input = this.container.querySelector('.reply-input');
+        const content = input.value.trim();
+        
+        if (!content) return;
+
+        try {
+            await this.onReply(content);
+            input.value = '';
+        } catch (error) {
+            console.error('Failed to submit reply:', error);
+            // Show error message to user
+        }
+    }
+
+    async resolveThread() {
+        try {
+            await this.onResolve();
+            this.render();
+        } catch (error) {
+            console.error('Failed to resolve thread:', error);
+            // Show error message to user
+        }
+    }
+
+    showReplyForm(commentId) {
+        const comment = this.container.querySelector(`[data-comment-id="${commentId}"]`);
+        if (!comment) return;
+
+        const replyForm = document.createElement('div');
+        replyForm.className = 'reply-form nested';
+        replyForm.innerHTML = `
+            <textarea
+                class="reply-input"
+                placeholder="Write a reply..."
+                rows="2"
+            ></textarea>
+            <div class="form-actions">
+                <button class="cancel-button" onclick="this.hideReplyForm('${commentId}')">
+                    Cancel
+                </button>
+                <button class="reply-button" onclick="this.submitNestedReply('${commentId}')">
+                    Reply
+                </button>
+            </div>
+        `;
+
+        comment.appendChild(replyForm);
+        replyForm.querySelector('.reply-input').focus();
+    }
+
+    hideReplyForm(commentId) {
+        const comment = this.container.querySelector(`[data-comment-id="${commentId}"]`);
+        if (!comment) return;
+
+        const replyForm = comment.querySelector('.reply-form');
+        if (replyForm) {
+            replyForm.remove();
+        }
+    }
+
+    async submitNestedReply(parentId) {
+        const comment = this.container.querySelector(`[data-comment-id="${parentId}"]`);
+        if (!comment) return;
+
+        const input = comment.querySelector('.reply-input');
+        const content = input.value.trim();
+        
+        if (!content) return;
+
+        try {
+            await this.onReply(content, parentId);
+            this.hideReplyForm(parentId);
+        } catch (error) {
+            console.error('Failed to submit reply:', error);
+            // Show error message to user
+        }
+    }
+
+    editComment(commentId) {
+        const comment = this.container.querySelector(`[data-comment-id="${commentId}"]`);
+        if (!comment) return;
+
+        const contentDiv = comment.querySelector('.comment-content');
+        const content = contentDiv.textContent;
+
+        contentDiv.innerHTML = `
+            <textarea class="edit-input" rows="2">${content}</textarea>
+            <div class="form-actions">
+                <button class="cancel-button" onclick="this.cancelEdit('${commentId}')">
+                    Cancel
+                </button>
+                <button class="save-button" onclick="this.saveEdit('${commentId}')">
+                    Save
+                </button>
+            </div>
+        `;
+    }
+
+    cancelEdit(commentId) {
+        // Refresh the entire thread to restore original content
+        this.render();
+    }
+
+    async saveEdit(commentId) {
+        const comment = this.container.querySelector(`[data-comment-id="${commentId}"]`);
+        if (!comment) return;
+
+        const input = comment.querySelector('.edit-input');
+        const content = input.value.trim();
+        
+        if (!content) return;
+
+        try {
+            // Emit edit event
+            const event = new CustomEvent('comment-edited', {
+                detail: { commentId, content }
+            });
+            this.container.dispatchEvent(event);
+            
+            // Refresh the thread
+            this.render();
+        } catch (error) {
+            console.error('Failed to edit comment:', error);
+            // Show error message to user
+        }
+    }
+}
+
+export default InlineCommentPanel;

static/js/components/version-comparison.js

@@ -0,0 +1,314 @@
+// Version Comparison Component
+
+class VersionComparison {
+    constructor(options = {}) {
+        this.container = null;
+        this.versions = new Map();
+        this.selectedVersions = new Set();
+        this.maxSelections = options.maxSelections || 3;
+        this.onCompare = options.onCompare || (() => {});
+        this.onRollback = options.onRollback || (() => {});
+        this.timeline = null;
+    }
+
+    initialize(containerId) {
+        this.container = document.getElementById(containerId);
+        if (!this.container) {
+            throw new Error(`Container element with id "${containerId}" not found`);
+        }
+        this._initializeTimeline();
+    }
+
+    setVersions(versions) {
+        this.versions = new Map(versions.map(v => [v.name, v]));
+        this._updateTimeline();
+        this.render();
+    }
+
+    _initializeTimeline() {
+        this.timeline = document.createElement('div');
+        this.timeline.className = 'version-timeline';
+        this.container.appendChild(this.timeline);
+    }
+
+    _updateTimeline() {
+        const sortedVersions = Array.from(this.versions.values())
+            .sort((a, b) => new Date(a.created_at) - new Date(b.created_at));
+
+        this.timeline.innerHTML = `
+            <div class="timeline-track">
+                ${this._renderTimelineDots(sortedVersions)}
+            </div>
+            <div class="timeline-labels">
+                ${this._renderTimelineLabels(sortedVersions)}
+            </div>
+        `;
+    }
+
+    _renderTimelineDots(versions) {
+        return versions.map(version => `
+            <div class="timeline-point ${this.selectedVersions.has(version.name) ? 'selected' : ''}"
+                 data-version="${version.name}"
+                 style="--impact-score: ${version.comparison_metadata.impact_score || 0}"
+                 onclick="this._toggleVersionSelection('${version.name}')">
+                <div class="point-indicator"></div>
+                ${this._renderImpactIndicator(version)}
+            </div>
+        `).join('');
+    }
+
+    _renderImpactIndicator(version) {
+        const impact = version.comparison_metadata.impact_score || 0;
+        const size = Math.max(8, Math.min(24, impact * 24)); // 8-24px based on impact
+        
+        return `
+            <div class="impact-indicator" 
+                 style="width: ${size}px; height: ${size}px"
+                 title="Impact Score: ${Math.round(impact * 100)}%">
+            </div>
+        `;
+    }
+
+    _renderTimelineLabels(versions) {
+        return versions.map(version => `
+            <div class="timeline-label" data-version="${version.name}">
+                <div class="version-name">${version.name}</div>
+                <div class="version-date">
+                    ${new Date(version.created_at).toLocaleDateString()}
+                </div>
+            </div>
+        `).join('');
+    }
+
+    render() {
+        if (!this.container) return;
+
+        const selectedVersionsArray = Array.from(this.selectedVersions);
+
+        this.container.innerHTML = `
+            <div class="version-comparison-tool">
+                <div class="comparison-header">
+                    <h3>Version Comparison</h3>
+                    <div class="selected-versions">
+                        ${this._renderSelectedVersions(selectedVersionsArray)}
+                    </div>
+                    <div class="comparison-actions">
+                        ${this._renderActionButtons(selectedVersionsArray)}
+                    </div>
+                </div>
+
+                ${this.timeline.outerHTML}
+
+                <div class="comparison-content">
+                    ${this._renderComparisonContent(selectedVersionsArray)}
+                </div>
+            </div>
+        `;
+
+        this.attachEventListeners();
+    }
+
+    _renderSelectedVersions(selectedVersions) {
+        return selectedVersions.map((version, index) => `
+            <div class="selected-version">
+                <span class="version-label">Version ${index + 1}:</span>
+                <span class="version-value">${version}</span>
+                <button class="remove-version" onclick="this._removeVersion('${version}')">
+                    ×
+                </button>
+            </div>
+        `).join('');
+    }
+
+    _renderActionButtons(selectedVersions) {
+        const canCompare = selectedVersions.length >= 2;
+        const canRollback = selectedVersions.length === 1;
+
+        return `
+            ${canCompare ? `
+                <button class="compare-button" onclick="this._handleCompare()">
+                    Compare Versions
+                </button>
+            ` : ''}
+            ${canRollback ? `
+                <button class="rollback-button" onclick="this._handleRollback()">
+                    Rollback to Version
+                </button>
+            ` : ''}
+        `;
+    }
+
+    _renderComparisonContent(selectedVersions) {
+        if (selectedVersions.length < 2) {
+            return `
+                <div class="comparison-placeholder">
+                    Select at least two versions to compare
+                </div>
+            `;
+        }
+
+        return `
+            <div class="comparison-results">
+                <div class="results-loading">
+                    Computing differences...
+                </div>
+            </div>
+        `;
+    }
+
+    _toggleVersionSelection(versionName) {
+        if (this.selectedVersions.has(versionName)) {
+            this.selectedVersions.delete(versionName);
+        } else if (this.selectedVersions.size < this.maxSelections) {
+            this.selectedVersions.add(versionName);
+        } else {
+            // Show max selections warning
+            this._showWarning(`Maximum ${this.maxSelections} versions can be compared`);
+            return;
+        }
+        this.render();
+    }
+
+    _removeVersion(versionName) {
+        this.selectedVersions.delete(versionName);
+        this.render();
+    }
+
+    async _handleCompare() {
+        const selectedVersions = Array.from(this.selectedVersions);
+        if (selectedVersions.length < 2) return;
+
+        try {
+            const results = await this.onCompare(selectedVersions);
+            this._renderComparisonResults(results);
+        } catch (error) {
+            console.error('Comparison failed:', error);
+            this._showError('Failed to compare versions');
+        }
+    }
+
+    async _handleRollback() {
+        const selectedVersion = Array.from(this.selectedVersions)[0];
+        if (!selectedVersion) return;
+
+        try {
+            await this.onRollback(selectedVersion);
+            // Handle successful rollback
+        } catch (error) {
+            console.error('Rollback failed:', error);
+            this._showError('Failed to rollback version');
+        }
+    }
+
+    _renderComparisonResults(results) {
+        const resultsContainer = this.container.querySelector('.comparison-results');
+        if (!resultsContainer) return;
+
+        resultsContainer.innerHTML = `
+            <div class="results-content">
+                ${results.map(diff => this._renderDiffSection(diff)).join('')}
+            </div>
+        `;
+    }
+
+    _renderDiffSection(diff) {
+        return `
+            <div class="diff-section">
+                <div class="diff-header">
+                    <h4>Changes: ${diff.version1} → ${diff.version2}</h4>
+                    <div class="diff-stats">
+                        <span class="computation-time">
+                            Computed in ${diff.computation_time.toFixed(2)}s
+                        </span>
+                        <span class="impact-score">
+                            Impact Score: ${Math.round(diff.impact_score * 100)}%
+                        </span>
+                    </div>
+                </div>
+                <div class="changes-list">
+                    ${this._renderChanges(diff.changes)}
+                </div>
+            </div>
+        `;
+    }
+
+    _renderChanges(changes) {
+        return changes.map(change => `
+            <div class="change-item">
+                <div class="change-header">
+                    <span class="change-type">${change.type}</span>
+                    <span class="change-file">${change.file}</span>
+                </div>
+                <div class="change-content">
+                    <div class="old-value">
+                        <div class="value-header">Previous</div>
+                        <pre>${this._escapeHtml(change.old_value)}</pre>
+                    </div>
+                    <div class="new-value">
+                        <div class="value-header">New</div>
+                        <pre>${this._escapeHtml(change.new_value)}</pre>
+                    </div>
+                </div>
+            </div>
+        `).join('');
+    }
+
+    _showWarning(message) {
+        const warning = document.createElement('div');
+        warning.className = 'comparison-warning';
+        warning.textContent = message;
+        this.container.appendChild(warning);
+        setTimeout(() => warning.remove(), 3000);
+    }
+
+    _showError(message) {
+        const error = document.createElement('div');
+        error.className = 'comparison-error';
+        error.textContent = message;
+        this.container.appendChild(error);
+        setTimeout(() => error.remove(), 3000);
+    }
+
+    _escapeHtml(text) {
+        const div = document.createElement('div');
+        div.textContent = text;
+        return div.innerHTML;
+    }
+
+    attachEventListeners() {
+        // Timeline scroll handling
+        const timeline = this.container.querySelector('.version-timeline');
+        if (timeline) {
+            let isDown = false;
+            let startX;
+            let scrollLeft;
+
+            timeline.addEventListener('mousedown', (e) => {
+                isDown = true;
+                timeline.classList.add('active');
+                startX = e.pageX - timeline.offsetLeft;
+                scrollLeft = timeline.scrollLeft;
+            });
+
+            timeline.addEventListener('mouseleave', () => {
+                isDown = false;
+                timeline.classList.remove('active');
+            });
+
+            timeline.addEventListener('mouseup', () => {
+                isDown = false;
+                timeline.classList.remove('active');
+            });
+
+            timeline.addEventListener('mousemove', (e) => {
+                if (!isDown) return;
+                e.preventDefault();
+                const x = e.pageX - timeline.offsetLeft;
+                const walk = (x - startX) * 2;
+                timeline.scrollLeft = scrollLeft - walk;
+            });
+        }
+    }
+}
+
+export default VersionComparison;

static/js/components/virtual-scroller.js

@@ -0,0 +1,190 @@
+// Virtual Scroller Component
+// Implements efficient scrolling for large lists by only rendering visible items
+
+class VirtualScroller {
+    constructor(options) {
+        this.container = options.container;
+        this.itemHeight = options.itemHeight;
+        this.bufferSize = options.bufferSize || 5;
+        this.renderItem = options.renderItem;
+        this.items = [];
+        this.scrollTop = 0;
+        this.visibleItems = new Map();
+        
+        this.observer = new IntersectionObserver(
+            this._handleIntersection.bind(this),
+            { threshold: 0.1 }
+        );
+        
+        this._setupContainer();
+        this._bindEvents();
+    }
+
+    _setupContainer() {
+        if (!this.container) {
+            throw new Error('Container element is required');
+        }
+
+        this.container.style.position = 'relative';
+        this.container.style.height = '600px'; // Default height
+        this.container.style.overflowY = 'auto';
+
+        // Create spacer element to maintain scroll height
+        this.spacer = document.createElement('div');
+        this.spacer.style.position = 'absolute';
+        this.spacer.style.top = '0';
+        this.spacer.style.left = '0';
+        this.spacer.style.width = '1px';
+        this.container.appendChild(this.spacer);
+    }
+
+    _bindEvents() {
+        this.container.addEventListener(
+            'scroll',
+            this._debounce(this._handleScroll.bind(this), 16)
+        );
+
+        // Handle container resize
+        if (window.ResizeObserver) {
+            const resizeObserver = new ResizeObserver(this._debounce(() => {
+                this._render();
+            }, 16));
+            resizeObserver.observe(this.container);
+        }
+    }
+
+    setItems(items) {
+        this.items = items;
+        this.spacer.style.height = `${items.length * this.itemHeight}px`;
+        this._render();
+    }
+
+    _handleScroll() {
+        this.scrollTop = this.container.scrollTop;
+        this._render();
+    }
+
+    _handleIntersection(entries) {
+        entries.forEach(entry => {
+            const itemId = entry.target.dataset.itemId;
+            if (!entry.isIntersecting) {
+                this.visibleItems.delete(itemId);
+                entry.target.remove();
+            }
+        });
+    }
+
+    _render() {
+        const visibleRange = this._getVisibleRange();
+        const itemsToRender = new Set();
+
+        // Calculate which items should be visible
+        for (let i = visibleRange.start; i <= visibleRange.end; i++) {
+            if (i >= 0 && i < this.items.length) {
+                itemsToRender.add(i);
+            }
+        }
+
+        // Remove items that are no longer visible
+        for (const [itemId] of this.visibleItems) {
+            const index = parseInt(itemId);
+            if (!itemsToRender.has(index)) {
+                const element = this.container.querySelector(`[data-item-id="${itemId}"]`);
+                if (element) {
+                    this.observer.unobserve(element);
+                    element.remove();
+                }
+                this.visibleItems.delete(itemId);
+            }
+        }
+
+        // Add new visible items
+        for (const index of itemsToRender) {
+            if (!this.visibleItems.has(index.toString())) {
+                this._renderItem(index);
+            }
+        }
+
+        // Update performance metrics
+        this._updateMetrics(itemsToRender.size);
+    }
+
+    _renderItem(index) {
+        const item = this.items[index];
+        const element = document.createElement('div');
+        
+        element.style.position = 'absolute';
+        element.style.top = `${index * this.itemHeight}px`;
+        element.style.left = '0';
+        element.style.width = '100%';
+        element.dataset.itemId = index.toString();
+
+        // Render content
+        element.innerHTML = this.renderItem(item);
+
+        // Add to container and observe
+        this.container.appendChild(element);
+        this.observer.observe(element);
+        this.visibleItems.set(index.toString(), element);
+
+        // Adjust actual height if needed
+        const actualHeight = element.offsetHeight;
+        if (actualHeight !== this.itemHeight) {
+            element.style.height = `${this.itemHeight}px`;
+        }
+    }
+
+    _getVisibleRange() {
+        const start = Math.floor(this.scrollTop / this.itemHeight) - this.bufferSize;
+        const visibleCount = Math.ceil(this.container.clientHeight / this.itemHeight);
+        const end = start + visibleCount + 2 * this.bufferSize;
+        return { start, end };
+    }
+
+    _updateMetrics(visibleCount) {
+        const metrics = {
+            totalItems: this.items.length,
+            visibleItems: visibleCount,
+            scrollPosition: this.scrollTop,
+            containerHeight: this.container.clientHeight,
+            renderTime: performance.now() // You can use this with the previous render time
+        };
+
+        // Dispatch metrics event
+        this.container.dispatchEvent(new CustomEvent('virtualScroller:metrics', {
+            detail: metrics
+        }));
+    }
+
+    _debounce(func, wait) {
+        let timeout;
+        return function executedFunction(...args) {
+            const later = () => {
+                clearTimeout(timeout);
+                func(...args);
+            };
+            clearTimeout(timeout);
+            timeout = setTimeout(later, wait);
+        };
+    }
+
+    // Public methods
+    scrollToIndex(index) {
+        if (index >= 0 && index < this.items.length) {
+            this.container.scrollTop = index * this.itemHeight;
+        }
+    }
+
+    refresh() {
+        this._render();
+    }
+
+    destroy() {
+        this.observer.disconnect();
+        this.container.innerHTML = '';
+        this.items = [];
+        this.visibleItems.clear();
+    }
+}
+
+export default VirtualScroller;

static/js/version-control.js

@@ -124,6 +124,289 @@ class VersionControl {
             .then(response => response.json());
     }
 
+    // Comment operations
+    async createComment(threadId, content, parentId = null) {
+        try {
+            const response = await fetch('/vcs/comments/create/', {
+                method: 'POST',
+                headers: {
+                    'Content-Type': 'application/json',
+                    'X-CSRFToken': this.getCsrfToken()
+                },
+                body: JSON.stringify({
+                    thread_id: threadId,
+                    content: content,
+                    parent_id: parentId
+                })
+            });
+
+            if (!response.ok) {
+                throw new Error('Failed to create comment');
+            }
+
+            const comment = await response.json();
+            return comment;
+        } catch (error) {
+            this.showError('Error creating comment: ' + error.message);
+            throw error;
+        }
+    }
+
+    async createCommentThread(changeId, anchor, initialComment) {
+        try {
+            const response = await fetch('/vcs/comments/threads/create/', {
+                method: 'POST',
+                headers: {
+                    'Content-Type': 'application/json',
+                    'X-CSRFToken': this.getCsrfToken()
+                },
+                body: JSON.stringify({
+                    change_id: changeId,
+                    anchor: anchor,
+                    initial_comment: initialComment
+                })
+            });
+
+            if (!response.ok) {
+                throw new Error('Failed to create comment thread');
+            }
+
+            const thread = await response.json();
+            return thread;
+        } catch (error) {
+            this.showError('Error creating comment thread: ' + error.message);
+            throw error;
+        }
+    }
+
+    async resolveThread(threadId) {
+        try {
+            const response = await fetch(`/vcs/comments/threads/${threadId}/resolve/`, {
+                method: 'POST',
+                headers: {
+                    'X-CSRFToken': this.getCsrfToken()
+                }
+            });
+
+            if (!response.ok) {
+                throw new Error('Failed to resolve thread');
+            }
+
+            return await response.json();
+        } catch (error) {
+            this.showError('Error resolving thread: ' + error.message);
+            throw error;
+        }
+    }
+
+    async editComment(commentId, content) {
+        try {
+            const response = await fetch(`/vcs/comments/${commentId}/`, {
+                method: 'PATCH',
+                headers: {
+                    'Content-Type': 'application/json',
+                    'X-CSRFToken': this.getCsrfToken()
+                },
+                body: JSON.stringify({
+                    content: content
+                })
+            });
+
+            if (!response.ok) {
+                throw new Error('Failed to edit comment');
+            }
+
+            return await response.json();
+        } catch (error) {
+            this.showError('Error editing comment: ' + error.message);
+            throw error;
+        }
+    }
+
+    async getThreadComments(threadId) {
+        try {
+            const response = await fetch(`/vcs/comments/threads/${threadId}/`);
+            if (!response.ok) {
+                throw new Error('Failed to fetch thread comments');
+            }
+            return await response.json();
+        } catch (error) {
+            this.showError('Error fetching comments: ' + error.message);
+            throw error;
+        }
+    }
+
+    initializeCommentPanel(containerId, options = {}) {
+        const panel = new InlineCommentPanel({
+            ...options,
+            onReply: async (content, parentId) => {
+                const comment = await this.createComment(
+                    options.threadId,
+                    content,
+                    parentId
+                );
+                const thread = await this.getThreadComments(options.threadId);
+                panel.setThread(thread);
+            },
+            onResolve: async () => {
+                await this.resolveThread(options.threadId);
+                const thread = await this.getThreadComments(options.threadId);
+                panel.setThread(thread);
+            }
+        });
+        panel.initialize(containerId);
+        return panel;
+    }
+
+    // Branch locking operations
+    async acquireLock(branchName, duration = 48, reason = "") {
+        try {
+            const response = await fetch('/vcs/branches/lock/', {
+                method: 'POST',
+                headers: {
+                    'Content-Type': 'application/json',
+                    'X-CSRFToken': this.getCsrfToken()
+                },
+                body: JSON.stringify({
+                    branch: branchName,
+                    duration: duration,
+                    reason: reason
+                })
+            });
+
+            if (!response.ok) {
+                throw new Error('Failed to acquire lock');
+            }
+
+            const result = await response.json();
+            if (result.success) {
+                this.refreshLockStatus(branchName);
+                return true;
+            }
+            return false;
+        } catch (error) {
+            this.showError('Error acquiring lock: ' + error.message);
+            return false;
+        }
+    }
+
+    async releaseLock(branchName, force = false) {
+        try {
+            const response = await fetch('/vcs/branches/unlock/', {
+                method: 'POST',
+                headers: {
+                    'Content-Type': 'application/json',
+                    'X-CSRFToken': this.getCsrfToken()
+                },
+                body: JSON.stringify({
+                    branch: branchName,
+                    force: force
+                })
+            });
+
+            if (!response.ok) {
+                throw new Error('Failed to release lock');
+            }
+
+            const result = await response.json();
+            if (result.success) {
+                this.refreshLockStatus(branchName);
+                return true;
+            }
+            return false;
+        } catch (error) {
+            this.showError('Error releasing lock: ' + error.message);
+            return false;
+        }
+    }
+
+    async getLockStatus(branchName) {
+        try {
+            const response = await fetch(`/vcs/branches/${encodeURIComponent(branchName)}/lock-status/`);
+            if (!response.ok) {
+                throw new Error('Failed to get lock status');
+            }
+            return await response.json();
+        } catch (error) {
+            this.showError('Error getting lock status: ' + error.message);
+            return null;
+        }
+    }
+
+    async getLockHistory(branchName, limit = 10) {
+        try {
+            const response = await fetch(
+                `/vcs/branches/${encodeURIComponent(branchName)}/lock-history/?limit=${limit}`
+            );
+            if (!response.ok) {
+                throw new Error('Failed to get lock history');
+            }
+            return await response.json();
+        } catch (error) {
+            this.showError('Error getting lock history: ' + error.message);
+            return [];
+        }
+    }
+
+    async refreshLockStatus(branchName) {
+        const lockStatus = await this.getLockStatus(branchName);
+        if (!lockStatus) return;
+
+        const statusElement = document.querySelector(`[data-branch="${branchName}"] .lock-status`);
+        if (!statusElement) return;
+
+        if (lockStatus.locked) {
+            const expiryDate = new Date(lockStatus.expires);
+            statusElement.className = 'lock-status locked';
+            statusElement.innerHTML = `
+                <svg class="lock-icon" viewBox="0 0 20 20" fill="currentColor">
+                    <path fill-rule="evenodd" d="M5 9V7a5 5 0 0110 0v2a2 2 0 012 2v5a2 2 0 01-2 2H5a2 2 0 01-2-2v-5a2 2 0 012-2zm8-2v2H7V7a3 3 0 016 0z" clip-rule="evenodd"/>
+                </svg>
+                <div class="lock-info">
+                    <span class="user">${lockStatus.user}</span>
+                    <span class="expiry">Expires: ${expiryDate.toLocaleString()}</span>
+                    ${lockStatus.reason ? `<span class="reason">${lockStatus.reason}</span>` : ''}
+                </div>
+            `;
+        } else {
+            statusElement.className = 'lock-status unlocked';
+            statusElement.innerHTML = `
+                <svg class="lock-icon" viewBox="0 0 20 20" fill="currentColor">
+                    <path d="M10 2a5 5 0 00-5 5v2a2 2 0 00-2 2v5a2 2 0 002 2h10a2 2 0 002-2v-5a2 2 0 00-2-2H7V7a3 3 0 015.905-.75 1 1 0 001.937-.5A5.002 5.002 0 0010 2z"/>
+                </svg>
+                <span>Unlocked</span>
+            `;
+        }
+
+        // Update lock controls
+        this.updateLockControls(branchName, lockStatus);
+    }
+
+    async updateLockControls(branchName, lockStatus) {
+        const controlsElement = document.querySelector(`[data-branch="${branchName}"] .lock-controls`);
+        if (!controlsElement) return;
+
+        if (lockStatus.locked) {
+            controlsElement.innerHTML = `
+                <button class="lock-button unlock" onclick="window.versionControl.releaseLock('${branchName}')">
+                    <svg class="w-4 h-4" viewBox="0 0 20 20" fill="currentColor">
+                        <path d="M10 2a5 5 0 00-5 5v2a2 2 0 00-2 2v5a2 2 0 002 2h10a2 2 0 002-2v-5a2 2 0 00-2-2H7V7a3 3 0 015.905-.75 1 1 0 001.937-.5A5.002 5.002 0 0010 2z"/>
+                    </svg>
+                    Unlock Branch
+                </button>
+            `;
+        } else {
+            controlsElement.innerHTML = `
+                <button class="lock-button lock" onclick="window.versionControl.acquireLock('${branchName}')">
+                    <svg class="w-4 h-4" viewBox="0 0 20 20" fill="currentColor">
+                        <path fill-rule="evenodd" d="M5 9V7a5 5 0 0110 0v2a2 2 0 012 2v5a2 2 0 01-2 2H5a2 2 0 01-2-2v-5a2 2 0 012-2zm8-2v2H7V7a3 3 0 016 0z" clip-rule="evenodd"/>
+                    </svg>
+                    Lock Branch
+                </button>
+            `;
+        }
+    }
+
     // Utility functions
     getCsrfToken() {
         return document.querySelector('[name=csrfmiddlewaretoken]').value;
@@ -149,7 +432,105 @@ class VersionControl {
     }
 }
 
+// Import DiffViewer component
+import DiffViewer from './components/diff-viewer.js';
+
 // Initialize version control
 document.addEventListener('DOMContentLoaded', () => {
     window.versionControl = new VersionControl();
+
+    // Initialize DiffViewer if diff container exists
+    const diffContainer = document.getElementById('diff-container');
+    if (diffContainer) {
+        window.diffViewer = new DiffViewer({
+            renderStrategy: 'side-by-side'
         });
+        diffViewer.initialize('diff-container');
+    }
+});
+
+// Add to VersionControl class constructor
+class VersionControl {
+    constructor() {
+        this.setupEventListeners();
+        this.diffViewer = null;
+        if (document.getElementById('diff-container')) {
+            this.diffViewer = new DiffViewer({
+                renderStrategy: 'side-by-side'
+            });
+            this.diffViewer.initialize('diff-container');
+        }
+    }
+
+    // Add getDiff method to VersionControl class
+    async getDiff(version1, version2) {
+        const url = `/vcs/diff/?v1=${encodeURIComponent(version1)}&v2=${encodeURIComponent(version2)}`;
+        try {
+            const response = await fetch(url);
+            if (!response.ok) {
+                throw new Error('Failed to fetch diff');
+            }
+            const diffData = await response.json();
+            
+            if (this.diffViewer) {
+                await this.diffViewer.render(diffData);
+            }
+            
+            return diffData;
+        } catch (error) {
+            this.showError('Error loading diff: ' + error.message);
+            throw error;
+        }
+    }
+
+    // Add viewChanges method to VersionControl class
+    async viewChanges(changeId) {
+        try {
+            const response = await fetch(`/vcs/changes/${changeId}/`);
+            if (!response.ok) {
+                throw new Error('Failed to fetch changes');
+            }
+            const changeData = await response.json();
+            
+            if (this.diffViewer) {
+                await this.diffViewer.render(changeData);
+            } else {
+                this.showError('Diff viewer not initialized');
+            }
+        } catch (error) {
+            this.showError('Error loading changes: ' + error.message);
+            throw error;
+        }
+    }
+
+    // Add addComment method to VersionControl class
+    async addComment(changeId, anchor, content) {
+        try {
+            const response = await fetch('/vcs/comments/add/', {
+                method: 'POST',
+                headers: {
+                    'Content-Type': 'application/json',
+                    'X-CSRFToken': this.getCsrfToken()
+                },
+                body: JSON.stringify({
+                    change_id: changeId,
+                    anchor: anchor,
+                    content: content
+                })
+            });
+            
+            if (!response.ok) {
+                throw new Error('Failed to add comment');
+            }
+            
+            const comment = await response.json();
+            if (this.diffViewer) {
+                this.diffViewer.addCommentThread(anchor, [comment]);
+            }
+            
+            return comment;
+        } catch (error) {
+            this.showError('Error adding comment: ' + error.message);
+            throw error;
+        }
+    }