Separation of concerns: Batch actions should not check user levels and trigger notifications

[camilapedraza]

Our batch actions are currently taking on the responsibility of checking user levels before and after running the actions, then identifying changes in levels, then triggering a notification if the level increased (here, here, here, and here)

It feels like checking changes in levels should not be part of the scope of batch actions. It should be its own function that can be called by any batch action (and by other features).

The check could live in the current badge_utils.py file or it could become a larger module. It would be within the scope of that function/utility/module to trigger notifications when it detects changes to user levels.

[mathjazz]

Great observation, and thanks for digging in.

One clarification worth making first: the level calculation is actually already extracted the way you're describing. badges_review_level / badges_translation_level live in base/badge_utils.py today, and batch actions import them from there. So the "shared function any feature can call" already exists for the leaf computation.

What isn't shared — and what I think you're really pointing at — is the workflow around those functions:

before_level = badges_review_level(user)
...do the work...
after_level = badges_review_level(user)
if after_level > before_level:
    badge_update = {...}
    send_badge_notification(...)

That "snapshot → re-check → notify on increase" dance is copy-pasted in five places:

• the four spots in batch/actions.py
• sync/utils.py
• translations/views.py
• base/forms.py

So your instinct is right, just one level up: it's not the level check that needs extracting (that's done), it's the level change detection + notification that should become its own reusable helper.

Two design questions I'd love your take on:

1. Should the helper also send the notification, or just report the change? Baking notification in is convenient, but it re-couples "detect" and "notify" — and several callers need the level-change info for their response payload regardless of notifications.
2. The promotion badge (base/forms.py) works off counts rather than levels, so folding it in cleanly needs a little extra care.

Really solid first find — well-scoped and it removes a genuinely bug-prone pattern.