@imvu/chkn

Read IMVU products: their CFL archives, their index.xml templates (with inheritance from parent products resolved the way the classic client does), and the Cal3D models they assemble (via @imvu/cal3d). Also converts to and from CHKN, the ZIP format IMVU's create mode opens.

No dependencies beyond @imvu/cal3d and no Node-only APIs (its own LZMA decoder, fetch, DecompressionStream), so it runs in Node ≥ 22 and in browsers.

import { CdnProductSource, Product } from '@imvu/chkn';

const source = new CdnProductSource({ revisions: { 53938393: 3, 512: 11 } });
const product = await Product.load(53938393, source);

product.ancestors.map((p) => p.id); // [512] — it derives from a base room
product.definition.productType; // 'Room'
product.definition.meshes; // Map { 0 => { asset: 'Room.MESH.xmf', … } }

const { skeleton, parts } = product.loadModel(); // @imvu/cal3d objects
for (const part of parts) {
  for (const submesh of part.mesh?.submeshes ?? []) {
    const { spec, material } = part.materials.get(submesh.materialId)!;
    spec.raw.TwoSided; // IMVU render settings for this slot
    const texture = await product.fetchAsset(material!.diffuseMap!.filename); // full-size, from the CDN
  }
}

const chkn = await product.toChkn(); // open in IMVU's create mode
const flat = await product.toChkn({ flatten: true }); // the whole ancestor chain in one file

How products fit together

• CFL (productdata/{pid}/{revision}): an archive of the product's files. Entries are LZMA-compressed. CflArchive.parse(bytes) reads it, and CflArchive.create(files) writes one (entries are stored uncompressed, which the client also accepts).
• index.xml: the product template. It names the skeleton, the mesh per body part, the material per mesh slot (TextureMapN, matched to Submesh.materialId by Index), actions, render settings, and so on. <__DATAIMPORT>product://{pid}/index.xml</__DATAIMPORT> makes it inherit from another product: the parent's settings fill in whatever the child doesn't set, and <Key delete="true"/> removes an inherited key. parseTemplate and expandTemplate follow the client's imvu/product/template.py exactly.
• Assets: a file name resolves in the product itself (its CFL entries and its _contents.json names), and failing that in its parent, and so on up the chain. product.getFile(name) reads from the CFLs, while product.fetchAsset(name) prefers the CDN for textures. Textures inside CFLs are 16×16 placeholders; the full-size file is the one _contents.json tags original, served at {cflUrl}/{url}.
• CHKN: a ZIP of a product's files. cflToChkn(cfl) repackages a CFL byte for byte, as the old cfl-converter did, while product.toChkn() also swaps in full-size textures. toChkn({ flatten: true }) rolls up the whole chain: the expanded template as index.xml (no __DATAIMPORT), every file reachable through the chain (the nearest product's copy wins on a name clash), and no _contents.json, whose CDN references no longer apply.

Revisions

A CFL URL needs the product's current revision, and parents are referenced without one. No REST field has it. Revisions are also not contiguous: product 512 has 5 and 8–11, but not 6–7. So:

• Best: give CdnProductSource real revisions. @imvu/xmlrpc's authorizeProducts([pid]) returns the product and every ancestor with its CFL URL:

  const auths = await gateway.authorizeProducts([productId]);
  const revisions = new Map(auths.map((a) => [a.productId, Number(a.cflUrl.split('/').pop())]));
  const product = await Product.load(productId, new CdnProductSource({ revisions }));

• Fallback: products without a known revision are probed with probeLatestRevision (HEAD requests: doubling, then a binary search, then a look past short gaps). It's a heuristic, and slow for deep chains with large revision numbers (tens of requests per product).

Or implement ProductSource yourself (e.g. to read CFLs from disk or a cache).

Not covered yet

Particle systems (ParticleSystems, default.particles.json), sounds, and the product-type predicates beyond productType are reachable through definition.template but have no typed accessors.