Addresses the adapter-setup pains: collapses the torch_cuda(trampolines)/torch_adapters/torch_ltx2 split
+ 11 near-identical adapter classes + 6 build_torch_* builders into:
- v2/platform/backends/torch_backend.py: a TorchComponent base centralizing .to/.eval, the numpy<->torch
marshalling (ONE place), the set_forward_context wrap, and the weight surface; thin per-model subclasses
(WanDiT/LTX2DiT/WanVAE/LTX2VAE/T5Encoder/Gemma/LTX2Upsampler/LTX2AudioVAE/LTX2Vocoder) carrying only
forward semantics; and ONE build_component(spec) dispatching by spec.kind via _MAKERS.
- torch_cuda.py: registers that single generic builder for all 6 cuda kinds (no per-kind trampolines).
- v2 owns its namespace via re-export STUBS (facade, marked '# STUB'): v2/forward_context, v2/fastvideo_args,
v2/distributed, v2/loader (the load_component seam), v2/api, v2/models/{dits,audio,upsamplers}/*. All v2
code imports v2.*; 'from fastvideo' now lives ONLY in those 8 stub files -> a future per-module vendored
cutover swaps a stub body, no caller changes. No divergence (stubs run fastvideo's live code).
- Deleted torch_adapters.py + torch_ltx2.py.
Verified: CPU mini 210 pass/2 skip; lazy invariant (platform load imports no torch); GPU bit-parity LTX-2.3
T2VS (audio std 0.04304, identical to pre-redesign) + Wan2.1 (video std 31.94, motion 5.997).
Will Lin
440b99523e