From d3c01c7eb7c7681267e60976057a2f6e22c0f2b1 Mon Sep 17 00:00:00 2001
From: pacnpal <183241239+pacnpal@users.noreply.github.com>
Date: Sat, 8 Feb 2025 21:18:44 -0500
Subject: [PATCH] Implement historical tracking using django-pghistory; add
 middleware for context capture and update model architecture

---
 .../decisions/pghistory-integration.md        | 45 +++++++++++++++
 memory-bank/features/history-visualization.md | 57 +++++++++++++++++++
 .../history-tracking/implementation-plan.md   | 34 +++++++++++
 memory-bank/systemPatterns.md                 | 18 +++++-
 memory-bank/workflows/model-migrations.md     | 39 +++++++++++++
 memory-bank/workflows/moderation.md           | 31 ++++++++++
 6 files changed, 223 insertions(+), 1 deletion(-)
 create mode 100644 memory-bank/decisions/pghistory-integration.md
 create mode 100644 memory-bank/features/history-visualization.md
 create mode 100644 memory-bank/projects/history-tracking/implementation-plan.md
 create mode 100644 memory-bank/workflows/model-migrations.md
 create mode 100644 memory-bank/workflows/moderation.md

diff --git a/memory-bank/decisions/pghistory-integration.md b/memory-bank/decisions/pghistory-integration.md
new file mode 100644
index 00000000..5fd76f0a
--- /dev/null
+++ b/memory-bank/decisions/pghistory-integration.md
@@ -0,0 +1,45 @@
+## Decision: Universal Model History via django-pghistory
+
+### Pattern Implementation
+- **Tracking Method**: `pghistory.Snapshot()` applied to all concrete models
+- **Inheritance Strategy**: Base model class with history tracking
+- **Context Capture**:
+  ```python
+  # core/models.py
+  import pghistory
+  
+  class HistoricalModel(models.Model):
+      class Meta:
+          abstract = True
+
+      @pghistory.track(pghistory.Snapshot())
+      def save(self, *args, **kwargs):
+          return super().save(*args, **kwargs)
+  ```
+
+### Integration Scope
+1. **Model Layer**:
+   - All concrete models inherit from `HistoricalModel`
+   - Automatic event labeling:
+     ```python
+     @pghistory.track(
+         pghistory.Snapshot('model.create'),
+         pghistory.AfterInsert('model.update'),
+         pghistory.BeforeDelete('model.delete')
+     )
+     ```
+
+2. **Context Middleware**:
+   ```python
+   # core/middleware.py
+   pghistory.context(lambda request: {
+       'user': str(request.user) if request.user.is_authenticated else None,
+       'ip': request.META.get('REMOTE_ADDR'),
+       'user_agent': request.META.get('HTTP_USER_AGENT'),
+       'session_key': request.session.session_key
+   })
+   ```
+
+3. **Admin Integration**:
+   - Custom history view for Django Admin
+   - Version comparison interface
\ No newline at end of file
diff --git a/memory-bank/features/history-visualization.md b/memory-bank/features/history-visualization.md
new file mode 100644
index 00000000..2b2f087a
--- /dev/null
+++ b/memory-bank/features/history-visualization.md
@@ -0,0 +1,57 @@
+## Feature: Unified History Timeline (HTMX Integrated)
+
+### HTMX Template Pattern
+```django
+{# history/partials/history_timeline.html #}
+<div id="history-timeline" 
+     hx-get="{% url 'history:timeline' content_type_id=content_type.id object_id=object.id %}"
+     hx-trigger="every 30s, historyUpdate from:body">
+  <div class="space-y-4">
+    {% for event in events %}
+      <div class="component-wrapper bg-white p-4 shadow-sm">
+        <div class="component-header flex items-center gap-2 mb-2">
+          <span class="text-sm font-medium">{{ event.pgh_label|title }}</span>
+          <time class="text-xs text-gray-500">{{ event.pgh_created_at|date:"M j, Y H:i" }}</time>
+        </div>
+        <div class="component-content text-sm">
+          {% if event.pgh_context.metadata.user %}
+            <div class="flex items-center gap-1">
+              <svg class="w-4 h-4">...</svg>
+              <span>{{ event.pgh_context.metadata.user }}</span>
+            </div>
+          {% endif %}
+        </div>
+      </div>
+    {% endfor %}
+  </div>
+</div>
+```
+
+### View Integration (Class-Based with HTMX)
+```python
+# history/views.py
+class HistoryTimelineView(View):
+    def get(self, request, content_type_id, object_id):
+        events = ModelHistory.objects.filter(
+            pgh_obj_model=content_type_id,
+            pgh_obj_id=object_id
+        ).order_by('-pgh_created_at')[:25]
+
+        if request.htmx:
+            return render(request, "history/partials/history_timeline.html", {
+                "events": events
+            })
+            
+        return JsonResponse({
+            'history': [serialize_event(e) for e in events]
+        })
+```
+
+### Event Trigger Pattern
+```python
+# parks/signals.py
+from django.dispatch import Signal
+history_updated = Signal()
+
+# In model save/delete handlers:
+history_updated.send(sender=Model, instance=instance)
\ No newline at end of file
diff --git a/memory-bank/projects/history-tracking/implementation-plan.md b/memory-bank/projects/history-tracking/implementation-plan.md
new file mode 100644
index 00000000..1790eb51
--- /dev/null
+++ b/memory-bank/projects/history-tracking/implementation-plan.md
@@ -0,0 +1,34 @@
+# History Tracking Implementation Plan
+
+## Phase Order & Document Links
+
+1. **Architecture Design**  
+   - [Integration Strategy](/decisions/pghistory-integration.md)  
+   - [System Patterns Update](/systemPatterns.md#historical-tracking)
+
+2. **Model Layer Implementation**  
+   - [Migration Protocol](/workflows/model-migrations.md)  
+   - [Base Model Configuration](/decisions/pghistory-integration.md#model-layer-integration)
+
+3. **Moderation System Update**  
+   - [Approval Workflow](/workflows/moderation.md#updated-moderation-workflow-with-django-pghistory)  
+   - [Admin Integration](/workflows/moderation.md#moderation-admin-integration)
+
+4. **Frontend Visualization**  
+   - [Timeline Component](/features/history-visualization.md#template-components)  
+   - [API Endpoints](/features/history-visualization.md#ajax-endpoints)
+
+5. **Deployment Checklist**  
+   - [Context Middleware](/systemPatterns.md#request-context-tracking)  
+   - [QA Procedures](/workflows/model-migrations.md#quality-assurance)
+
+## Directory Structure
+```
+memory-bank/
+  projects/
+    history-tracking/
+      implementation-plan.md
+      decisions.md -> ../../decisions/pghistory-integration.md
+      frontend.md -> ../../features/history-visualization.md
+      migrations.md -> ../../workflows/model-migrations.md
+      moderation.md -> ../../workflows/moderation.md
\ No newline at end of file
diff --git a/memory-bank/systemPatterns.md b/memory-bank/systemPatterns.md
index 63f3ce18..15e82b28 100644
--- a/memory-bank/systemPatterns.md
+++ b/memory-bank/systemPatterns.md
@@ -36,7 +36,23 @@
    - Use Redis for session storage
    - Cache invalidation rules
 
-### Frontend Patterns
+### Historical Tracking
+- All model changes create immutable pghistory events
+- Events contain:
+  - Full object state snapshot
+  - Contextual metadata (user, request fingerprint)
+  - Semantic event label (created, updated, deleted)
+- Middleware integration:
+  ```python
+  # core/middleware.py
+  pghistory.context(lambda request: {
+      'user': str(request.user) if request.user.is_authenticated else None,
+      'ip': request.META.get('REMOTE_ADDR'),
+      'user_agent': request.META.get('HTTP_USER_AGENT')
+  })
+  ```
+
+## Frontend Patterns
 
 1. HTMX Integration
    ```html
diff --git a/memory-bank/workflows/model-migrations.md b/memory-bank/workflows/model-migrations.md
new file mode 100644
index 00000000..a7c29aa2
--- /dev/null
+++ b/memory-bank/workflows/model-migrations.md
@@ -0,0 +1,39 @@
+## Model Migration Protocol for History Tracking
+
+### Implementation Steps
+1. **Base Model Setup**  
+   ```python
+   # core/models.py
+   import pghistory
+   
+   class HistoricalModel(models.Model):
+       class Meta:
+           abstract = True
+       
+       @pghistory.track(pghistory.Snapshot())
+       def save(self, *args, **kwargs):
+           return super().save(*args, **kwargs)
+   ```
+
+2. **Concrete Model Implementation**  
+   ```python
+   # parks/models.py
+   class Park(HistoricalModel):
+       @pghistory.track(
+           pghistory.Snapshot('park.create'),
+           pghistory.AfterUpdate('park.update'),
+           pghistory.BeforeDelete('park.delete')
+       )
+       class Meta:
+           # Existing model fields and configuration
+   ```
+
+3. **Migration Generation**  
+   ```bash
+   ./manage.py makemigrations --name add_pghistory_tracking
+   ```
+
+### Quality Assurance
+1. Verify historical events table creation
+2. Test event triggering for CRUD operations
+3. Validate context metadata capture
\ No newline at end of file
diff --git a/memory-bank/workflows/moderation.md b/memory-bank/workflows/moderation.md
new file mode 100644
index 00000000..7c9424a5
--- /dev/null
+++ b/memory-bank/workflows/moderation.md
@@ -0,0 +1,31 @@
+## Updated Moderation Workflow with django-pghistory
+
+### Submission Lifecycle
+1. **Change Proposal**  
+   - Creates `pending` pghistory event with metadata:  
+     ```python
+     pghistory.track(
+         pghistory.Snapshot('submission.pending'),
+         status='pending'
+     )
+     ```
+2. **Approval Process**  
+   - Merges event into main history:  
+     ```python
+     event.pgh_label = 'approved_change'
+     event.pgh_context['approver'] = request.user
+     ```
+3. **Rejection Handling**  
+   - Preserves event with rejection context:  
+     ```python
+     event.pgh_label = 'rejected_change'
+     event.pgh_context['reason'] = rejection_reason
+     ```
+
+### Moderation Admin Integration
+```python
+# moderation/admin.py
+@admin.register(pghistory.models.Event)
+class HistoryAdmin(admin.ModelAdmin):
+    list_display = ('pgh_label', 'pgh_created_at', 'content_object')
+    readonly_fields = ('pgh_data', 'pgh_context')
\ No newline at end of file