Work on creating more of the necessary data models

module/config.mjs

@@ -8,10 +8,10 @@ const ammoTypes = [`quivers`, `mags`, `cells`];
 
 const stats = [ `build`, `meta`, `presence`, `hands`, `tilt`, `rng` ];
 
-const buildSkills = [ "defense", "magic", "melee", "platforming", "strength", ];
-const metaSkills = [ "alchemy", "arcanum", "dreams", "lore", "navigation", ];
-const presenceSkills = [ "animal_handling", "perception", "sneak", "speech", "vibes", ];
-const handsSkills = [ "accuracy", "crafting", "engineering", "explosives", "piloting", ];
+const buildSkills = [ `defense`, `magic`, `melee`, `platforming`, `strength`, ];
+const metaSkills = [ `alchemy`, `arcanum`, `dreams`, `lore`, `navigation`, ];
+const presenceSkills = [ `animal_handling`, `perception`, `sneak`, `speech`, `vibes`, ];
+const handsSkills = [ `accuracy`, `crafting`, `engineering`, `explosives`, `piloting`, ];
 
 const allSkills = [
 	...buildSkills,
@@ -27,6 +27,11 @@ const skills = {
 	hands: handsSkills,
 };
 
+const itemTiers = [
+	`simple`, `greater`,
+	`rare`, `legendary`
+];
+
 export default {
 	stats,
 	statDice,
@@ -39,4 +44,5 @@ export default {
 	handsSkills,
 	allSkills,
 	skills,
+	itemTiers,
 };

module/documents/Actor/Handler.mjs

@@ -1,5 +1,6 @@
 import PlayerActor from "./Player.mjs";
 
+/** @extends {Actor} */
 export class ActorHandler extends Actor {
 	proxyTargets = {
 		player: PlayerActor,

module/documents/Item/Handler.mjs

@@ -1,13 +1,11 @@
 import AspectItem from "./Aspect.mjs";
+import SpellItem from "./Spell.mjs";
 
-/**
- * @extends {Item}
- */
+/** @extends {Item} */
 export class ItemHandler extends Item {
-	/** @override */
-
 	proxyTargets = {
 		aspect: AspectItem,
+		spell: SpellItem
 	};
 
 	constructor(data, ctx) {
@@ -19,6 +17,11 @@ export class ItemHandler extends Item {
 		return this.proxyTargets[this.type];
 	};
 
+	async migrateSystemData() {
+		if (!this.fn?.migrateSystemData) return;
+		this.fn?.migrateSystemData.bind(this)();
+	};
+
 	async proxyFunction(funcName, ...args) {
 		if (!this.fn?.[funcName]) return;
 		return await this.fn?.[funcName].bind(this)(...args);

module/documents/Item/Spell.mjs

@@ -0,0 +1,10 @@
+import { ItemHandler } from "./Handler.mjs";
+
+/** @this {ItemHandler} */
+async function migrateSystemData() {
+	this.system
+};
+
+export default {
+	migrateSystemData,
+};

module/models/Item/CommonItemData.mjs

@@ -1,11 +1,22 @@
+import { itemTiers } from "../../config.mjs";
+
 export class CommonItemData extends foundry.abstract.TypeDataModel {
 	static defineSchema() {
 		const fields = foundry.data.fields;
 		return {
-			cost: new fields.NumberField({
+			buy: new fields.NumberField({
 				initial: null,
 				nullable: true,
 			}),
+			usage_cost: new fields.NumberField({
+				initial: null,
+				nullable: true,
+			}),
+			tier: new fields.StringField({
+				initial: `simple`,
+				nullable: false,
+				choices: itemTiers,
+			}),
 		};
 	};
 };

module/models/Item/Equipment.mjs

@@ -0,0 +1,15 @@
+import { DescribedItemData } from "./DescribedItemData.mjs";
+
+export class EquipmentItemData extends DescribedItemData {
+	static defineSchema() {
+		const fields = foundry.data.fields;
+		return mergeObject(super.defineSchema(), {
+			extra_inventory: new fields.NumberField({
+				initial: null,
+				nullable: true,
+				required: false,
+			}),
+			material
+		});
+	};
+};

module/models/Item/Pet.mjs

@@ -4,7 +4,6 @@ export class PetItemData extends DescribedItemData {
 	static defineSchema() {
 		const fields = foundry.data.fields;
 		return mergeObject(super.defineSchema(), {
-			purchase: new fields.NumberField({ initial: 0, }),
 			upkeep: new fields.NumberField({ intial: null, nullable: true }),
 			pokeballd: new fields.BooleanField({ initial: false }),
 		});

module/models/Item/Transportation.mjs

@@ -8,10 +8,6 @@ export class TransportationItemData extends DescribedItemData {
 				initial: null,
 				nullable: true,
 			}),
-			purchase: new fields.NumberField({
-				initial: null,
-				nullable: true,
-			}),
 			upkeep: new fields.NumberField({
 				initial: null,
 				nullable: true,