Hi,

To grant read-only access to records while allowing all users to post comments in Odoo 18.0 Enterprise, create a record rule that restricts write access for specific user groups on the desired model. Then, create a custom Odoo module and inherit the same model in a Python file. Override the message_post method, adding self.with_context(mail_create_nolog=True) before calling the super method.

This bypasses access rights checks specifically for creating comments, allowing users with read-only access to still post comments. Ensure your custom module depends on the mail module and thoroughly test the configuration to confirm that users can only access records as intended and can post comments.

Hope it helps

 Key Point: Even with read-only access on the main model, users need Create permission on mail.message to post comments in the chatter.

I hope this information helps you

Thanks & Regards,
Kunjan Patel