fix: contract course asset URLs to /static/ before saving xblock data (LP-704)

[djoseph-apphelix]

Description

Fixes LP-704: Studio bakes course-pinned absolute asset URLs into stored xblock content, breaking JSInput problems and images after a course re-run or export/import.

Jira Ticket

LP-704

Root cause

The authoring read/write round-trip is asymmetric:

• get_block_info runs replace_static_urls, expanding portable /static/<name> references into absolute asset-v1:<Org>+<Course>+<Run>+... URLs pinned to the current course (cms/djangoapps/contentstore/xblock_storage_handlers/view_handlers.py).
• _save_xblock persists the POSTed data verbatim — nothing contracts those URLs back.

The client editor is the only safety net, and not every editor path contracts every attribute (e.g. the course-authoring MFE misses JSInput's html_file). Any save through a non-contracting path permanently bakes the current course's id into storage. After a re-run, those URLs still point at the original course: assets 404 for learners (or silently serve stale content from the old course while it happens to be public).

The fix

• New contract_static_urls(text, course_id) in common/djangoapps/static_replace/__init__.py — the reverse of replace_static_urls for a course's own assets. It contracts all forms back to /static/<name>:
  • …+type@asset+block@<name> and …+type@asset+block/<name>
  • host-qualified (https://host/asset-v1:…) and protocol-relative
  • versioned (/assets/courseware/v1/<digest>/asset-v1:…)
  • legacy /c4x/<org>/<course>/asset/<name>
  • preserves query strings; leaves other courses' asset URLs and genuine external URLs untouched.
• _save_xblock now runs string data through contract_static_urls before persisting, so course-pinned URLs are never stored regardless of which editor performed the save.

rewrite_nonportable_content_links (store_utilities.py) was considered for reuse but never matches split-mongo course ids — its pattern is not re.escaped, so the + separators act as regex quantifiers. That is a separate pre-existing bug.

Testing

• 8 new unit tests in common/djangoapps/static_replace/test/test_static_replace.py covering all URL forms, query-string preservation, foreign-course/external URLs left untouched, and non-string passthrough.
• 2 new integration tests in cms/djangoapps/contentstore/views/tests/test_block.py: saving data with a baked same-course URL stores /static/<name>; another course's asset URL is preserved verbatim.
• Verified end to end on devstack: a JSInput problem with a baked html_file URL heals on the next save, and re-saving portable content no longer bakes it.

Screenshots

Before

After the fix

Companion frontend fix: edx/frontend-app-authoring#106

[Copilot]

Pull request overview

This PR prevents Studio from persisting course-pinned (non-portable) absolute asset URLs inside stored XBlock data, by contracting same-course asset URLs back to portable /static/<name> before saving.

Changes:

• Added contract_static_urls(text, course_id) to reverse replace_static_urls for same-course asset URLs (including versioned, host-qualified, and legacy /c4x/ forms).
• Updated _save_xblock to contract URLs in string data prior to persisting xblock.data.
• Added unit and integration tests to verify contraction behavior and that foreign-course URLs are preserved.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
common/djangoapps/static_replace/init.py	Adds contract_static_urls implementation for contracting same-course asset URLs back to /static/.
common/djangoapps/static_replace/test/test_static_replace.py	Adds unit tests covering contraction across multiple URL forms and passthrough behavior.
cms/djangoapps/contentstore/xblock_storage_handlers/view_handlers.py	Contracts same-course asset URLs in string data before saving XBlock content.
cms/djangoapps/contentstore/views/tests/test_block.py	Adds integration tests ensuring saved data is portable and foreign-course URLs remain unchanged.

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.