Display charms

To show charms in a wallet, extract them from the transaction that produced the UTXO. The charms-lib WebAssembly module exposes extractAndVerifySpell, which parses a transaction, verifies its spell proof, and returns the charms.

Get the WASM module

Use the charms_lib.wasm module — available as a release artifact or built from charms-lib.

Create JS bindings:

wasm-bindgen --out-dir target/wasm-bindgen-nodejs --target nodejs path/to/charms_lib.wasm

Extract and verify

Pass a chain-tagged transaction to extractAndVerifySpell(tx, mock):

const wasm = require('./target/wasm-bindgen-nodejs/charms_lib.js');

const tx = { bitcoin: "020000000001…" };   // the raw transaction hex
const spell = wasm.extractAndVerifySpell(tx, false);
console.log(spell);

The returned spell describes the charms in the transaction’s outputs:

{
  version: 15,
  tx: {
    ins: [ '13aa92ea…:1' ],
    outs: [ Map(1) { 0 => 40000000000 } ]
  },
  app_public_inputs: Map(1) {
    't/3d7fe7e4…/c975d4e0…' => undefined
  }
}

What you get

extractAndVerifySpell(tx, mock) returns the spell object for the transaction:

• App specifications — each app’s tag (n NFT, t token, s Scroll, or custom), 32-byte identity, and 32-byte verification key vk.
• Inputs — the UTXO ids spent.
• Outputs with charms — each output maps an app (by index) to its charm content: an amount for fungible tokens, or arbitrary data for NFTs and other apps.

Render in the wallet

1. Scan UTXOs. For each UTXO, extract charms from the transaction that created it.
2. Parse the returned spell to get each output’s charms.
3. Render by type: show an NFT’s image and name prominently; show a token’s amount alongside its name/symbol and image.
4. Show metadata. NFTs are recommended (not required) to follow CHIP-0420 for their content structure (ticker, name, image, …).