[#1401, #1620, #1626] Item Choice Advancement

[arbron]

Introduces the item choice advancement for choosing one or more options when you reach a level, usable for things like Fighting Style, Metamagic, or Signature Spells.

The player can select an option from a predefined list like Fighting Style:

Item.Choice.-.Basic.webm

Or they can drop items onto the advancement such as with Magical Secrets:

Item.Choice.-.Drops.webm

If a choice is available over multiple levels like Metamagic, the previously made choices will be shown:

Item.Choice.-.Previous.Choices.webm

Configuration is handled through an interface similar to Grant Items, but with the level list allowing to specify how many choices are available at which levels:

This also adds the ability to configure spells that are added through Item Grant or Item Choice advancements, setting ability, preparation mode, and limited uses:

Resolves #1401
Resolves #1620
Resolves #1626

[MaxPat931]

Warlock Invocations provides the option to swap out previous choices for a new one (and Tasha's added a few Optional Class Features that allow for this as well), would it be feasible to build in a Modify Choices button for the Previous Choices view, or some other way to modify them after making the choice?

[Fyorl]

Rather than this being a new type of advancement, I believe we planned to add this functionality to the existing ItemGrant advancement. Conceptually they are the same: An item grant where you are given X options and must take all X of them, vs an item grant where you are given X options and must take Y of them.

[arbron]

Rather than this being a new type of advancement, I believe we planned to add this functionality to the existing ItemGrant advancement. Conceptually they are the same: An item grant where you are given X options and must take all X of them, vs an item grant where you are given X options and must take Y of them.

I believe there are enough differences, particularly with choices that span multiple levels. We'd either have to graft the level code onto ItemGrant where it doesn't have any use and have it exist for all item grants or force users to duplicate ItemChoice advancements for different levels, potentially leading to a large data duplication (see Warlock invocations which have dozens of entries across nearly as many levels).

The ItemChoice advancement also has a bunch of code to handle user-dropped choices during advancement and validating spell levels which are unnecessary for ItemGrant.

[Fyorl]

Is it not the case that ItemChoice is a strict superset of ItemGrant though? As in, any existing ItemGrant could be implemented as an ItemChoice instead? Maybe there would have to be some small tweaks to make that true, like a checkbox for 'optional' where, if unchecked, all the available items are granted instead of offering a choice.

It seems like for the Fighting Style example, which has only a single item in its level table, it could be equally implemented as an ItemGrant with optional: true, and an additional field like choices: 1.

If that's the case and they are interchangeable in this way, or where one is a strict superset of the other, then I don't think it makes sense to have both of them. It feels like it would be preferable to combine them in some way in order to keep code reuse to a maximum and reduce our API surface.

I think that's what our goal originally was with ItemGrant, which is why it has the optional field at all. But it seems we've deviated from that trajectory somewhat here.