[Refactor] Slash-n-Burn Discussion BuiltIn XBlock

[irfanuddinahmad]

See parent epic: openedx/openedx-platform#37819

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Rollout Position

Step 6 of 8 — The XBlock file itself is small (310 LOC), but extra smoke testing is warranted: the extracted Discussion toggle was previously reverted before being re-enabled (feat: enable extracted discussion xblock followed by a prior revert). The lms/djangoapps/discussion/ Django app (34K LOC) is out of scope and is not being removed.

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Block Details

Toggle	USE_EXTRACTED_DISCUSSION_BLOCK in openedx/envs/common.py
Shim class	_BuiltInDiscussionXBlock in xmodule/discussion_block.py
Entrypoint	discussion = "xmodule.discussion_block:DiscussionXBlock" in pyproject.toml

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Checklist

Pre-condition

• Review PRs merged into the built-in Discussion XBlock code in edx-platform after the extraction work was done — port any bug fixes or improvements to xblocks-contrib if not already there.

Steps (single PR)

• Remove the toggle — delete USE_EXTRACTED_DISCUSSION_BLOCK from openedx/envs/common.py and all usages.
• Remove the shim — delete _BuiltInDiscussionXBlock class and the from xblocks_contrib.discussion import DiscussionXBlock as _ExtractedDiscussionXBlock import from xmodule/discussion_block.py.
• Remove the entrypoint — delete discussion = "xmodule.discussion_block:DiscussionXBlock" from pyproject.toml.
• Remove remaining assets:
  • xmodule/discussion_block.py (Python class)
  • xmodule/js/src/discussion/display.js (JavaScript)
  • Any remaining CSS/template files specific to the built-in block
• Run smoke tests on the extracted Discussion block to verify nothing is broken. Pay extra attention given the prior toggle revert history.

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Scope Notes

Out of scope for this issue:

• lms/djangoapps/discussion/ — the full discussion forum Django app (89 files, 34K LOC). This is a separate service that remains in edx-platform regardless of this XBlock removal.

[irfanuddinahmad]

Implementation PR: openedx/openedx-platform#38749