Match Kolibri's v2 contentnode and channel filters

[rtibblesbot]

Summary

• Kolibri browsing Studio got course nodes it excluded; search, question and contains_exercise were ignored; contains_quiz=false still returned quizzes.
• Public content nodes store modality at publish; a deploy-migrate backfill fills existing ones.
• v2/contentnode and v2/channel apply Kolibri's filter and search semantics.

References

Fixes #6171.

Reviewer guidance

• Existing public nodes have NULL modality until deploy-migrate finishes. Until then exclude_modalities=COURSE excludes nothing. Is that acceptable?
• The backfill is one unbatched UPDATE over every public node with a modality in options. Is that fast enough on production data?
• keywords now matches each term against title or description, the way Kolibri does. It used to need every term in the title, or every term in the description. The tree endpoint now searches too.

AI usage

Used Claude Code to vendor Kolibri's filters and annotate_modality, and to write the tests and backfill command. Verified with the kolibri_public test suite, flake8, black, makemigrations --check and lintmigrations.

🤖 Generated with Claude Code

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@rtibblesbot's comments are generated by an LLM, and should be evaluated accordingly

How was this generated?

• Ran pre-flight CI checks (lint, format, tests) and verified all pass
• Rebased onto the target branch and resolved any conflicts
• Reorganized commit history into clean, logical commits
• Audited the diff to ensure only issue-relevant files are changed
• Built PR body from the repository's PR template with evidence blocks

🟡 Waiting for feedback Last updated: 2026-09-25 00:14 UTC