The runtime text_encoder_quant=fp8 path downloads the full bf16 text
encoder and layerwise-casts it in place on every fresh load. For the
heavyweight encoders (LTX's Gemma3-27B ~50 GB, FLUX.2-dev's Mistral-24B
~48 GB, Qwen-Image's Qwen2.5-VL ~16.6 GB) that download dominates load
time on a fresh machine.
diffusion_te_prequant.py loads a pre-cast fp8-storage state dict
instead: meta-init the encoder skeleton from the checkpoint's te_class,
load_state_dict(assign=True), rebuild on CPU if non-persistent buffers
stay on meta, then re-apply the same layerwise cast to install the
upcast hooks. The cast is a deterministic storage transform, so the
loaded encoder is bit-identical to dense-load-then-cast by construction.
v1 hosts the layerwise fp8 storage scheme only: its state dict is plain
tensors (torch.load(weights_only=True), no pickle execution). The
dynamic-compute schemes (fp8_dynamic, int8, nvfp4) build torchao
subclass wrappers at runtime and are deliberately not hosted.
Checkpoints validate format, scheme, component and base_model_id before
use and any problem falls back to the dense download and cast. Local
path overrides reuse the DiT prequant allowlist env var. Families opt in
via a new te_prequant_repos (scheme, component, repo_id) field on both
DiffusionFamily and VideoFamily; the field defaults empty so nothing
changes until a gate-validated artifact is wired.
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