Django Code Doctor

Django's defaults make several expensive mistakes easy and invisible: a loop that issues a query per row reads exactly like a loop that doesn't, a template can hit the database with nothing in the Python to show for it, and an endpoint that checks you are logged in looks identical to one that checks you own the row. This skill finds those mechanically, then gives you the judgment to decide what to do.

It does three jobs:

• Review — fifteen detectors over an existing project.
• Upgrade — what breaks between the Django this project is on and the one you want, with the severity derived from the target.
• Author — references/django-idioms.md is prescriptive: one canonical answer per task, version-tagged, for writing Django that does not need this skill's other half later.