feat: split read vs write authz checks for library updates

[wgu-taylor-payne]

Description

Updates the downstream sync v2 endpoints to use courses.view_library_updates for read access (list/summary) and courses.manage_library_updates for write access (sync/decline).

Previously, the list endpoint used has_studio_read_access (legacy only, no authz integration), and the sync/decline endpoints used has_studio_write_access. This meant Course Auditors were blocked from even viewing library update status. Per the design in openedx/openedx-authz#283, auditors should see the library updates page in read-only mode.

User roles impacted: Course Auditor — can now view (but not sync/decline) library updates when authz is enabled.

Changes:

• cms/djangoapps/contentstore/rest_api/v2/views/downstreams.py:
  • DownstreamListView.get: Use COURSES_VIEW_LIBRARY_UPDATES for course-filtered requests
  • DownstreamSummaryView.get: Use COURSES_VIEW_LIBRARY_UPDATES instead of COURSES_VIEW_COURSE
  • _load_accessible_block: Use COURSES_MANAGE_LIBRARY_UPDATES for write, COURSES_VIEW_LIBRARY_UPDATES for read
  • Removed unused has_studio_read_access/has_studio_write_access imports
• Tests: 5 new tests verifying editor can list+sync, auditor can list but not sync, unauthorized gets 403

Rollback: Gated behind AUTHZ_COURSE_AUTHORING_FLAG — disabling the flag triggers legacy fallback via user_has_course_permission.

Supporting information

• Closes Add courses.view_library_updates enforcement in openedx-platform openedx-authz#398
• Related: Design: Course Editor & Course Auditor screen restrictions openedx-authz#283

Testing instructions

1. Enable AUTHZ_COURSE_AUTHORING_FLAG for a course with library-linked components
2. Assign a user the course_auditor role
3. GET /api/contentstore/v2/downstreams/?course_id={course_id} → 200
4. GET /api/contentstore/v2/downstreams/{course_id}/summary → 200
5. POST /api/contentstore/v2/downstreams/{usage_key}/sync → 404 (permission denied)
6. Assign course_editor → sync should succeed (200 or 400 depending on upstream state)
7. User with no role → list returns 403

Deadline

None

AI Usage

Kiro was used as a development partner throughout this PR. I directed the implementation approach, defined scope, reviewed generated code, and made design decisions — Kiro researched the codebase, wrote the implementation and tests, ran lint/type checks, and iterated on fixes. I verified the changes manually against a local Tutor dev environment and reviewed the final diffs before submitting.

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[mariajgrimaldi]

Out of curiosity. Why is this part of the changes?

[rodmgwgu]

My understanding is that previously, we always allowed anyone with view course permissions to see the available library updates, now we want to restrict it to only people with the view library updates permission, so this would be correct to include in these changes.

[rodmgwgu]

Are you sure this function will always be used for course keys? Given the description, it seems this is used for loading XBlocks, so this would break that functionality.

Perhaps we should conditionally test for different permissions depending if it's a course or something else, or understand if this will ever used to check for courses or not.

[BryanttV]

Thanks for the PR! @wgu-taylor-payne

I've been testing the GET endpoints, and they are working correctly for the different roles (Course Auditor/Course Editor).

However, for the functionality to work completely, we still need to work on:

• The GET endpoint (http://meilisearch.local.openedx.io:7700/multi-search) currently doesn't validate RBAC permissions. This will be addressed in the issue you reported: openedx/openedx-authz#417
• The POST endpoint /api/contentstore/v2/downstreams/{usage_key}/sync: Although this PR updates the XBlock loading step to use RBAC, it subsequently validates whether the user has permissions for the library being synced. It shouldn't work this way. Users with the Course Admin/Staff/Editor role should be able to sync library changes within their assigned courses simply by validating the courses.manage_library_updates permission. This will be addressed in this issue: openedx/openedx-authz#419

I think we can merge this PR and open additional ones related to the other tasks. What do you think, @rodmgwgu?

[rodmgwgu]

Thanks for the PR! @wgu-taylor-payne

I've been testing the GET endpoints, and they are working correctly for the different roles (Course Auditor/Course Editor).

However, for the functionality to work completely, we still need to work on:

• The GET endpoint (http://meilisearch.local.openedx.io:7700/multi-search) currently doesn't validate RBAC permissions. This will be addressed in the issue you reported: openedx/openedx-authz#417
• The POST endpoint /api/contentstore/v2/downstreams/{usage_key}/sync: Although this PR updates the XBlock loading step to use RBAC, it subsequently validates whether the user has permissions for the library being synced. It shouldn't work this way. Users with the Course Admin/Staff/Editor role should be able to sync library changes within their assigned courses simply by validating the courses.manage_library_updates permission. This will be addressed in this issue: openedx/openedx-authz#419

I think we can merge this PR and open additional ones related to the other tasks. What do you think, @rodmgwgu?

I would like to wait for @wgu-taylor-payne to confirm if validating for course keys only in _load_accessible_block is correct, as otherwise it could break other code.