Official SF checkpoint wlsaidhi/SFWan2.1-T2V-1.3B-Diffusers (reuses TorchWanVAE + TorchT5Encoder).
- TorchWanDiT detects the causal transformer: ignores the chunk_rollout loop's latent `context` (the
real model conditions across chunks via an internal kv_cache, not a forward arg) -> dispatches to
full-attention _forward_train, and passes a per-latent-frame timestep [B, num_frames] (the causal
block asserts a per-frame temb), uniform per chunk.
- chunk_rollout real geometry on cuda (16ch; chunk_size latent frames; 8x spatial).
e2e: chunk_rollout over the SF student -> coherent video (cat in a garden), (3,21,480,832). Fidelity
gap (artifacts): the v2 loop's per-chunk few-step sampling != the official kv-cache streaming + SF
schedule (a follow-up).
SolitaryThinker
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