This update modernizes how several Odoo apps connect related business records behind the scenes. It should make future maintenance easier and more consistent across CRM, Delivery, Fleet, Recruitment, Mail, Maintenance, Mass Mailing, Product, Project, and Users without changing day-to-day workflows.

Task: https://www.odoo.com/web#id=30596&view_type=form&model=project.task&action=333&active_id=248&menu_id=4720

This update strengthens the Mail app's automated test coverage around activities, access rights, and performance. It helps reduce the risk of regressions in reminders and activity-related workflows without introducing a direct user-facing change.

Description of the issue/feature this PR addresses:

Current behavior before PR:

Desired behavior after PR is merged:


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