FunPackNVFP4ModelLoader quantizes an existing bf16/fp16 checkpoint to NVFP4
at load time as a pure state-dict transform: selected 2D Linears are
re-serialized in ComfyUI core's quantized-checkpoint format (packed fp4
weights + fp8-e4m3 block scales + fp32 tensor scale + per-layer comfy_quant
metadata) and handed to the stock loading path. Core's MixedPrecisionOps
then does everything: real FP4 tensor-core GEMMs on sm_100+ (sm_120 incl.),
dynamic activation scales (no calibration pass), per-layer LoRA fallback,
and dequant emulation on older GPUs. No custom forward, no monkeypatching.
Zone-aware precision map for the joint AV transformer: default scope
quantizes only video-branch Linears (attn1/attn2/ff) of the middle blocks;
the audio branch, the audio<->video cross-modal bridges, the first/last N
blocks, and all non-matmul weights stay full precision. Scopes widen to
+cross-modal, all blocks, and all 2D layers for experimentation.
Tests drive the REAL comfy.quant_ops/comfy.ops via comfy_kitchen's eager
backend on CPU: scope selection, serialized-format contract, prefix
handling, refusal of pre-quantized checkpoints, and a load+forward
roundtrip through MixedPrecisionOps on both the NVFP4 and emulation paths.
The Movie Editor Models modal picks the node up automatically as a
Unet/Diffusion Model candidate (object_info-driven).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
