Description

Currently, assignment due dates in Moodle can show up in different ways depending on whether it's a default due date, an extension or a user/group override.

Here's what I've observed:

• When I create an assignment, a due date event is created. This shows up fine in both calendar and timeline block.
• When I grant a user an extension, Moodle creates another event (with eventtype = extension). This shows up in the calendar only, not in the timeline block.
• Then, if I add a user override, the extension event is removed from the database and a new due date event is created for the user override. This override event becomes the only one shown in the calendar and timeline block.

So depending on what's been added, the same user might:

• See multiple due dates in the calendar (default + extension), (override + extension), or
• The timeline and calendar can disagree, showing different due dates
• Lose visibility on the assignment extension altogether if an override is added, even if it's still relevant for submission logic

Suggested improvements

• Calendar and timeline block should both show the effective due date for the student: whichever is latest among the default, override or extension.
• Dates that are superseded should not be displayed (or at least not shown prominently).
• Ideally, there would be a single utility function that figures out the one correct deadline for each user and that’s what gets shown in both calendar and timeline.