The video loader always materialised the dense DiT(s) inside from_pretrained
and quantised them in place, so an int8/fp8 A14B load paid a ~57 GB dense
download and a dense-bf16 VRAM transient every time. Mirror the image loader's
hosted-prequant shortcut:
- diffusion_prequant grows an expert dimension: prequant_repo_filename /
prequant_filename / resolve_prequant_source take an expert attribute name, so
one repo carries a dual-DiT pair per scheme (<Model>-<SCHEME>.pt plus
<Model>-<SCHEME>-2.pt, legacy transformer_2_<scheme>.pt fallback), and
load_prequantized_transformer meta-inits from the expert's config subfolder.
A local path override never carries a pair, so an expert request under an
override resolves None and the whole load falls back to dense.
- VideoFamily gains prequant_repos (+ variant table for parity with the image
side); wired: Wan2.2-TI2V-5B and both A14B expert pairs at int8 + fp8, and
HunyuanVideo-1.5 480p/720p at int8 only per the measured deny list. LTX stays
unwired (no measured quant recipe).
- The pipeline build tries the shortcut first when the resolved plan is
resident and every expert's checkpoint resolves; loaded experts ride into
from_pretrained as component overrides and in-place quantise is skipped.
All-or-none per pair: a partial load frees and goes dense (mixed-precision
experts would corrupt the boundary handoff).
- An explicit wired scheme also lets the scoped pre-download skip the DiT
weight shards (configs kept for the meta-init); if the shortcut then falls
through, the build resolves from the hub id, gated on the same predicate so
ordinary pre-downloaded snapshots are untouched.
- build_prequant_checkpoint.py accepts --subfolder and resolves video families.
New tests: expert filename/resolution conventions, family wiring incl. the
LTX/720p split, shortcut engagement, partial-pair dense fallback, unwired
family bypass, and the pre-download skip predicate.
4e23ebc902