See MDL-78066, where it was reported that workshop causes an error during deep linking, because it had multiple grade items. While this particular bug is easily resolved there (by ensuring a declarative line item binding isn't possible in cases where the activity has multiple grade items), we still should consider how we'd like to (properly) support these kinds of cases when it comes to grade sync.

The legacy LTI provider doesn't support deep linking so it didn't have to consider that part of it, but it did sync the grades for the first grade item it saw when calling grade_get_grades - see this code. That's naive, of course, but it did sync something (FWIW in my testing, the first grade it received was the submission grade)

The LTI Advantage provider grade sync code copied this same logic (since that was about getting feature parity with legacy at the time it was worked on).

This issue is scoped with improving this for the LTI Advantage case only. Legacy is now deprecated and we're not adding new features to that any more.

Possible options include:

1. Allow multiple line items and grades to be managed by the tool in the platform (my preference). This means the platform gradebook would show two line items (created by the tool code) and users would have a grade for each one. This would work the same way for all activities having more that a single grade item (e.g. forum, others?).
2. Provide some form of aggregation mechanism (as discussed by Liam on MDL-78066). This needs more thought because not all activities would want this. There may be some that would prefer single line items to be synced. The mechanism doesn't exist for this, essentially, and would likely be quite a bit more work than 1.