- recipes/subtask_joint.yaml: paper-style single sequence (pi0.5 §IV-B) —
the supervised subtask span gets text CE and conditions the FAST and
flow losses in the same forward.
- joint_subtask_conditioning config flag rebuilds the same layout at
inference: state on the task turn, generated subtask as a causal
assistant turn (encode_prompt_with_targets + lang_causal_marks through
sample_actions), in both the policy select_action path and the runtime
adapter.
- fast_skip_tokens default 128 -> 1152 so FAST codes land below the <loc>
range and never collide with VQA loc targets; _FAST_ACTION_VOCAB_SIZE
tightened to the universal tokenizer's 1024 codes.
- Strip the trailing space from the 'Assistant:' generation prefill —
SentencePiece folds the space into the first target token, so the
space-suffixed prefill ended in a lone '▁' never seen in training.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Pepijn Kooijmans