CRITICAL fix: torch.compile'd expert saved as expert._orig_mod.* -> from_pretrained silently dropped it (random flow head at eval). Save the uncompiled module

train_fast: non-persistent hub workers (recycle each epoch to reset leaks)

train_fast: v4 all-channels via hub stream (support passthrough, morph_text tokenization, guarded shard morph block)

fix DDP hang: spawn dataloader workers (fork-after-CUDA/NCCL starved torchrun heartbeat), picklable Collate, fewer workers per rank

fix: yaml 1.1 parses '2250.0e12' as string -> float() cast in MFU calc (crashed first log step)

train_fast: torchrun DDP (per-rank streaming, rank0 logging/saves, global throughput)

tinyvla_b200: B200 streaming training on nvidia/physical-ai (745 samples/s e2e, 7x ViT fast path, hub episode streaming, full instructions)