Extends the existing lazy-load pattern for text_encoder, tokenizer,
and audio_vae to the video VAE: each MagiHuman variant's converted
repo no longer needs to bundle a copy of the Wan 2.2 TI2V-5B VAE.
The four cross-variant shared components are now all fetched from
their canonical upstream HF repos at first build:
* text_encoder, tokenizer -> google/t5gemma-9b-9b-ul2 (gated)
* audio_vae -> stabilityai/stable-audio-open-1.0 (gated)
* vae -> Wan-AI/Wan2.2-TI2V-5B-Diffusers
Per-variant converted repo shrinks to transformer/ + scheduler/ +
model_index.json (~5 GB for base bf16, ~30 GB for distill bf16). All
variants share the same ~25 GB cache of upstream weights, so a user
running 4 variants ends up with ~75 GB total instead of ~400 GB.
Implementation:
* fastvideo/utils.py:verify_model_config_and_directory now treats
the contents of model_index.json as authoritative for which
component subfolders must exist locally. Pipelines that emit a
minimal model_index.json (omitting vae / text_encoder / etc.)
pass verification; pipelines that DO declare a component must
still ship its subfolder. transformer/ remains mandatory.
* fastvideo/pipelines/basic/magi_human/magi_human_pipeline.py adds
vae to the deferred list in load_modules and a new
_load_video_vae helper that prefers a bundled vae/ subfolder
(legacy converted repos) and falls back to snapshot_download +
the standard FV VAELoader. Both paths produce the same FV
AutoencoderKLWan, so production behavior is unchanged.
* convert_magi_human_to_diffusers.py docstring updated; --bundle-vae
flag is unchanged (still optional) but the README example now
omits it so new converted repos default to the minimal layout.
Verification:
* basic_magi_human.py with bundled vae/: byte-identical mp4 (md5
dcf5f2bf...) to pre-refactor output.
* basic_magi_human.py with vae/ moved out and removed from
model_index.json: same byte-identical mp4 via the lazy-load path.
* 4/4 magi-human parity tests pass with diff_max=0.0 / diff_mean=0.0
(DiT, pipeline, smoke + typed surface preflight).