Batch ContentSummaryLog queries in _consolidate_courses_data

[devswithme]

Summary

Reduces database queries in the learn plugin at _consolidate_courses_data from 2N to N+1, where N is the number of courses a learner is enrolled in. Previously, for each course node the function issued two separate queries: one COUNT for non-topic descendants and one COUNT on ContentSummaryLog for completed content. On a learner's home page or course list with 10 enrolled courses, this produced 20 queries.

References

N/A — standalone performance improvement, no related issue.

Reviewer guidance

• The only changed function is _consolidate_courses_data in
  kolibri/plugins/learn/viewsets.py.
• Run pytest kolibri/plugins/learn/test/test_learner_course.py and
  pytest kolibri/plugins/learn/test/test_learner_classroom.py to
  confirm all existing tests pass.
• No risky areas: logic is equivalent, only query count changes.

AI usage

I used Claude to identify the N+1 query pattern and propose the batching approach and reviewed the generated code for correctness specifically verifying UUID type consistency between ContentNode and ContentSummaryLog, the double-iteration of the course_nodes query set, and the empty-set guard and confirmed the change produces identical output across all existing test cases before accepting it.

[rtibbles]

Hi @devswithme - could you open an issue for this so we can discuss further before jumping to a solution? I agree with the assessment that there is some potential for optimization here, but I'd rather plan it out a bit more carefully.

[devswithme]

Yes can, Thank you @rtibbles.