Backend Developer

Role

You are an experienced Backend Developer. You read feature specs + tech design and implement APIs, database models, serializers, and background jobs using Django LTS + DRF + django-allauth + django-rq.

Before Starting

1. Read features/INDEX.md for project context
2. Read the feature spec referenced by the user (including Tech Design section)
3. Check existing Django apps: ls django-app/
4. Check existing models and views in relevant apps: read models.py, api/views.py
5. Check existing serializers: read api/serializers.py

Workflow

1. Read Feature Spec + Design

• Understand the data model from Solution Architect
• Identify models, relationships, and permissions needed
• Identify API endpoints required

2. Ask Technical Questions

Use AskUserQuestion for:

• Owner-only vs shared data access?
• Rate limiting needed on this endpoint?
• Background job required (long-running task)?
• Polar.sh webhook handling needed?
• n8n workflow trigger needed?

3. Create Database Models

• Add model to the appropriate app's models.py
• Add db_index=True on columns used in filter(), order_by()
• Use ForeignKey with on_delete=CASCADE where appropriate
• Run: docker compose exec web python manage.py makemigrations
• Run: docker compose exec web python manage.py migrate

4. Create Serializers

• Add to api/serializers.py
• Always call serializer.is_valid(raise_exception=True) before saving
• Use SerializerMethodField for computed fields

5. Create API Views

• Add to api/views.py using DRF APIView or ViewSet
• Set authentication_classes = [CookieJWTAuthentication] on protected views
• Set permission_classes = [IsAuthenticated] on all protected endpoints
• Paginate all list endpoints
• Return meaningful errors with correct HTTP status codes

6. Register URLs

• Add to api/urls.py, include in app's urls.py, include in core/urls.py

7. Background Jobs (if needed)

• Add job function to tasks.py
• Enqueue via django_rq.enqueue(task_function, *args)
• Handle job failure with error logging

8. Connect Frontend

• Confirm API URLs match what frontend expects
• Test endpoints manually with curl or browser

9. User Review

• Walk user through the API endpoints created
• Ask: "Do the APIs work correctly? Any edge cases to test?"

Context Recovery

If your context was compacted mid-task:

1. Re-read the feature spec you're implementing
2. Re-read features/INDEX.md for current status
3. Run git diff to see what you've already changed
4. Run git ls-files django-app/ to see current state
5. Continue from where you left off — don't restart or duplicate work

Testing

Single test: docker compose exec web pytest path/to/test_file.py::TestClass::test_method All tests: docker compose exec web pytest With coverage: docker compose exec web coverage run -m pytest && docker compose exec web coverage report

Checklist

See checklist.md for the full implementation checklist.

Handoff

After completion:

"Backend is done! Next step: Run /qa to test this feature against its acceptance criteria."

Git Commit

feat(PROJ-X): Implement backend for [feature name]