Metadata format

Resolving the URL

function tokenURI(uint256 tokenId) external view returns (string);

tokenURI returns baseURI concatenated with the decimal token id, with no separator — which is why baseURI always ends in /.

Read baseURI() on-chain; never hardcode the host

baseURI is owner-updatable. A hardcoded host breaks silently — you keep fetching a stale origin and see no error, just old data. Call tokenURI (or read baseURI() once and cache it briefly).

tokenURI reverts for a token that does not exist, which includes burned tokens.

Document shape

{
  "name": "AK-47 | Redline (Field-Tested)",
  "description": "Tokenized CS2 Gun held in LootFi custody.",
  "image": "https://community.cloudflare.steamstatic.com/economy/image/...",
  "rarity": "Classified",
  "wear": "Field-Tested",
  "float": 0.2374091,
  "paintSeed": 661,
  "paintIndex": 316,
  "fadePercentage": null,
  "dopplerPhase": null,
  "statTrak": false,
  "souvenir": false,
  "stickers": [
    { "slot": 0, "stickerId": 6689, "wear": 0.91, "name": "Sticker | Example", "imageUrl": "https://..." }
  ],
  "steamAssetId": "52941493200",
  "attributes": [
    { "trait_type": "Category",          "value": "Gun" },
    { "trait_type": "Rarity",            "value": "Classified" },
    { "trait_type": "Wear",              "value": "Field-Tested" },
    { "trait_type": "Float",             "value": 0.2374091, "display_type": "number" },
    { "trait_type": "Paint Seed",        "value": 661,       "display_type": "number" },
    { "trait_type": "Paint Index",       "value": 316,       "display_type": "number" },
    { "trait_type": "Stickers",          "value": 1,         "display_type": "number" },
    { "trait_type": "Steam Fingerprint", "value": "730:2:52941493200:1989338770:302028390" }
  ]
}

Fields

Field	Type	Notes
name	string	Steam market hash name; falls back to LootFi #<id>
description	string	Generated from the category
image	string | null	Steam CDN URL
rarity	string | null	e.g. Covert, Classified
wear	string | null	Exterior name, e.g. Field-Tested
float	number | null	0–1 wear value
paintSeed	number | null	Pattern index — 0 is valid
paintIndex	number | null	Skin identifier
fadePercentage	number | null	Fade skins only
dopplerPhase	string | null	Doppler/Gamma Doppler only
statTrak	boolean
souvenir	boolean
stickers	array | null	[] = inspected, none applied
steamAssetId	string	Metadata only — never the token id
attributes	array	Standard NFT traits; null-valued traits are omitted

Semantics that break naive consumers

Three traps

1. null means "not looked up yet", not "the item has none." Stat enrichment can only run once a custody account physically holds the item, so a freshly minted token often has nulls that fill in later.
2. paintSeed: 0 is a real seed, and some seed-0 patterns are valuable. if (paintSeed) silently drops them. Test != null.
3. stickers: [] ≠ stickers: null. Empty array = inspected, no stickers. Null = not inspected. Rendering both as "no stickers" is wrong.

The same trap appears in the category ordinals — Gun is 0. Never test truthiness on protocol values.

Not every item has stats

Float, paint seed and stickers exist only for inspectable items — guns, knives, gloves. Graffiti, containers, capsules and music kits are not inspectable, so those fields stay null for them.

null on its own does not tell you which case you are in. It means this value is not present in the metadata, which covers both "this kind of item never has one" and "it has not been looked up yet". Do not infer absence from null, and do not cache it as final — an empty list (stickers: []) is the only positive statement that something genuinely has none.

Mutability

The document is mutable in one direction: stat enrichment can rewrite it after mint as data resolves. The item identity — which physical asset backs the token — never changes.

Practical guidance: cache with a short TTL and re-fetch a token whose stats are null. Do not cache a null-heavy document indefinitely and assume it is final.

Rendering suggestions

• Lead with name and image; both are populated at mint.
• Show wear (the human exterior) next to float (the precise value). Traders want both; float alone is unreadable to most users.
• Surface paintSeed for knives and gloves — pattern hunters search on it.
• Badge statTrak and souvenir; they materially affect value.
• Hide a stat rather than rendering "null" or "0" when it is absent.