The vanilla advancement JSON format allows specifying XP, loot tables, recipe unlocks, and function executions as rewards for completing an advancement.

The loot table reward can be useful for modpack makers, however, it's inconvenient, because it gives you the reward instantly, even if you're in a situation where your inventory is full; or players just get confused as they receive a random item while doing some task.

It would be cool to have behavior closer to the various "quest" mods:

• Not give rewards immediately
• Display a ! on top of the advancement tab/button, and on top of an advancement with an unclaimed reward
• Clicking on that advancement gives you the loot rewards

Vanilla MC actually uses this to give a bit of XP for completing challenge advancements, so maybe for compatibility, XP could be an exception to this?

I do like this as a feature request, but it doesn't fit in the scope of Better Advancements.
I want the mod to be QoL and remain client-only. A change like this will require some type of server interaction.

I'll leave this open, as I do want to investigate it and see how much work it would need server side.

Gonna close this as I will stick to QoL features only.