# Bootstrap backbones

DA3-Giant backbone weight used by `DA3GiantEncoder.__init__` to instantiate
the Stage 1 model before our finetuned `student_da3` state_dict is loaded
on top. This file is the same one referenced as `stage_1.ckpt_path` in
every training config in this lineage.

## Files

- `track4world_da3.pth` (~5.2 GB) — DA3-Giant multi-view backbone weights.
  Load with `torch.load(map_location='cpu')`. Used only at model
  instantiation; the finetuned `student_da3` weights inside any
  `franka_multitask_v1/*/0XXXXXX.pt` checkpoint override these on
  `load_state_dict`.

## Other dependencies (NOT in this repo — fetch from public HF)

- `google-t5/t5-base` (~900 MB): language encoder used by the shallow12 AR
  predictor (`predictor.language_encoder_type: t5`).
- `openai/clip-vit-large-patch14` (~1.7 GB): only referenced in the config;
  the multi-task finetune actually routes through T5, so CLIP weights are
  loaded but unused at inference. Safe to skip on bandwidth-constrained
  deploy hosts.

Both download automatically on first `transformers`/`huggingface_hub` call;
configure `HF_HOME` if the deploy host needs an offline mirror.

## Deploy load order

```python
# 1. Instantiate DA3GiantEncoder with this backbone bootstrap.
encoder = DA3GiantEncoder(
    ckpt_path="/local/track4world_da3.pth",
    ...,
)
# 2. Strict-load the finetuned student weights on top.
finetune = torch.load("/local/franka_multitask_0010000.pt", map_location="cpu")
encoder.load_state_dict(finetune["student_da3"], strict=True)
```

See `docs/realrobot-franka-deploy-handoff.md` in
[ONground-Korea/3DA](https://github.com/ONground-Korea/3DA) for the full
deploy spec.