Register flux.2-klein and flux.2-dev in the DiT trainer following the
upstream DreamBooth references: latents train patchified and batch-norm
normalized from the VAE posterior mode, the packed forward reuses
step-invariant position ids, and the guidance vector (3.5) is gated on
the variant's guidance_embeds config. Conditioning stacks load per
variant (Mistral via Flux2Pipeline for dev, Qwen3 via Flux2KleinPipeline
for Klein) and are encoded and freed before the transformer lands on the
device. The fused single-stream to_qkv_mlp_proj joins the attention
projections in the LoRA targets; the single-stream out projection stays
dense because its to_out suffix would also match the double-stream
ModuleList container.
Wire both families through the training registry (family set, labels,
VRAM notes, rank 16 / lr 1e-4 defaults, bf16-only preflight), mark them
trainable with train base repos in the family registry, add FLUX.2-dev
to the gated-repo token check, and trust both official bases for
training downloads.
Verified on B200: 30-step klein int8 (19.6s) and nf4 (20.9s) and dev
int8 (52.0s) runs train with finite decreasing loss and the saved
adapters apply on the bf16 base pipeline (weight 0 reproduces the base
image exactly, weight 1 visibly restyles it).
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