inventory

One inventory model for a party, a loadout and a starship designer. Pure and Babylon-free: things, the holders they are in, and moves between them that are checked against rules and either happen completely or not at all. What the things ARE, what the rules say and what a loadout adds up to are the consumer's, supplied as plug-ins; nothing game-specific ships here. See INVENTORY-DESIGN.md for why it is shaped this way.

import { createInventory } from 'tosijs-3d'

const inv = createInventory(
  {
    items: { s1: { id: 's1', kind: 'sword', qty: 1 } },
    holders: {
      hero: { id: 'hero', containers: {
        hands: { type: 'slots', slots: { left: { accepts: ['hand'], holds: null }, right: { accepts: ['hand'], holds: null } } },
        bag: { type: 'list', holds: ['s1'] },
      } },
    },
  },
  { kinds: { sword: { id: 'sword', tags: ['hand', 'weapon'], mass: 3, contributes: { damage: 6 } } } }
)

inv.move({ item: 's1', to: { holder: 'hero', container: 'hands', slot: 'right' } })
inv.totals('hero') // { mass: 3, damage: 6 }

The pieces

• A kind (from the catalogue the consumer supplies) carries the facts: tags, mass, size (a grid footprint), cost, boxes (how many separately-destroyed boxes it is) and contributes (numbers it adds to its holder when fitted).
• An item is an instance: { id, kind, qty }, plus whatever the consumer adds (props: durability, quality, charges) and damaged (boxes lost).
• A holder owns containers, each one of three shapes: slots (named sockets, each accepting by tag), a list (a bag, optionally capped), or a grid (cells, an item covering its footprint).
• A move takes an item (or a new one from the catalogue: kind) to a place. Moves are applied to a COPY, every rule is asked about the result, and only a clean result is kept: all or nothing. stage() gives a draft that collects moves (a cart, a barter, an uncommitted design) and commits them together.

Plug-ins

The built-in rules are only the shapes': a slot takes what its accepts tags allow and one thing at a time, a list respects maxCount, a grid's items stay inside it and do not overlap.