Context

django-tasks-db is the ORM-backed backend for Django Tasks, the queue that ships with Django 6.0. We have two approaches. Should we leverage a third-party backend for Django Tasks, or should we work directly with the callback hooks and make our own implementations?

A spike resolved claiming by adding an override point to DatabaseBackend in django-tasks-db, with the MongoDB implementation subclassing it from django-mongodb-extensions. It leaves django-tasks-db free of MongoDB-specific code, claims each task exactly once under contention, and leaves SQLite unchanged at 97 passing tests with its original 16 skips. The prototype, the reproductions and a draft upstream issue are in this gist.

Someone needs to also re-spike this ticket to investigate using it without the third party library

Definition of done

• Agree whether to leverage the third party extension or manage the implementation ourselves in django-mongodb-extensions.

Pitfalls

• Maintainer could decline, requiring us to push forward with our own solution.
• Don't branch on has_select_for_update. SQLite reports False too and relies on BEGIN EXCLUSIVE, so keying on that flag routes SQLite down the wrong path.
• migrate crashes on MongoDB until INTPYTHON-1082 lands, or until django-mongodb-extensions carries the interim index patch from the gist.