# posttrain-ckpt-2000 — bounded post-train of the released T-Rex midtrain checkpoint

Weights of the 2000-step post-training run `trex_posttrain_public_0728_1300`
from https://github.com/physercoe/trex-repro (see `docs/EVAL.md`).

- **Base**: officially released T-Rex *midtrain* checkpoint (upstream:
  https://github.com/ZhuoyangLiu2005/T-Rex; arXiv:2606.17055).
- **Data**: 144 episodes (shard 0) of the public `zekaiwang/trex_dataset`,
  adapted on-the-fly to the eef-62 schema (`scripts/trex_public_dataset.py`).
- **Config**: MAX_STEPS=2000, bsz 4, lr 1e-4, bf16; train loss 1.48 →
  ~0.07–0.23; val @1999 act=0.0588, tac=0.1152.
- **Files**: `model.pt` (single-file torch checkpoint, ~8.5 GB — weights only,
  no optimizer state), `config.json`, `training_args.json`, `stats_data.json`,
  `processor/` (tokenizer/preprocessor). Load with the repo's own
  `model_load` (`repo/scripts/test.py`) — the format round-trips through its
  auto-detect.
- **Finding** (candid): open-loop, this post-train did not make the tactile
  expert input-responsive (probes ~5e-4 before and after) — see the repo
  README and `docs/EVAL.md`, Finding P3.

License: MIT. Derived from the T-Rex authors' released checkpoint — cite
arXiv:2606.17055.