H3 packs reference blocks into the sequence itself (own position grid, never denoised,
never rendered), which is the thing Best-FaceID approximated on LTX with overlap tokens
plus a trained ArcFace projector. On H3 there is nothing to project and nothing to slice
back off, so this is the model's own feature, not a port of that one.
A reference has to reach the model twice and in the same order both times: as
presentation (Qwen sees "<Picture 1>: <vision block>" so the prompt can name it) and as
a packed latent block. Those encodes happen in different nodes, so the ordered spec
travels between them:
- Studio owns the CLIP: resolves the reference list, bakes the presentation via the
tokenizer's minimax_ref_items, and records what it presented as funpack_h3_refs on
the conditioning. Reference media and a first-frame anchor are separate conditioning
modes, so source_image steps aside (loudly) when references are present.
- Chain Sampler owns the VAE: encodes exactly that list, in that order, sized against
the scene's canvas, and attaches minimax_refs. Applied on every scene branch so an
identity holds across the whole chain, and cached per run so it is encoded once
rather than once per scene.
Order is the contract — drop or reorder an entry and "<Picture 2>" points at a
different reference than the text encoder saw. Anything that cannot be encoded is
dropped AND named, and an audio reference lost for want of an audio_vae says out loud
that later <Audio j> labels have shifted.
New optional audio_vae input on the Chain Sampler (audio references only; image
references need just the main vae). Video references are refused with a reason rather
than half-implemented — they need 2 fps frame sampling and a video loader FunPack does
not own.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
