## Description
Article edits now ignore an `author_id` that does not belong to the
current account, retain the existing author, and still apply other valid
article changes. Article creation continues to reject cross-account
authors with a generic validation error and without creating a record.
The authenticated article serializers still omit authors without a
current-account membership so existing forged or stale records cannot
expose agent profile fields. The guard now checks `current_account_user`
directly to make that intent explicit.
## Closes
Follow-up to [CW-7665](https://linear.app/chatwoot/issue/CW-7665) and
[#15191](https://github.com/chatwoot/chatwoot/pull/15191).
## Type of change
- [x] Bug fix (non-breaking change which fixes an issue)
## How Has This Been Tested?
- Creating an article with a cross-account author returns `422` and does
not create an article.
- Updating an article with a cross-account author retains the previous
author while applying other valid attributes.
- Articles whose previous author is no longer an account member can
still be edited without exposing that author's agent profile.
- Existing OSS and Enterprise article request coverage passes locally.
## Checklist:
- [x] My code follows the style guidelines of this project
- [x] I have performed a self-review of my code
- [x] My changes generate no new warnings
- [x] I have added tests that prove my fix is effective or that my
feature works
- [x] New and existing unit tests pass locally with my changes
- [x] Any dependent changes have been merged and published in downstream
modules
Co-authored-by: Vishnu Narayanan <iamwishnu@gmail.com>
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