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7a32f8a72a
Previously ``action_execution`` rendered ``task + plan + memory +
subtask`` into one prefix and ran the flow loss on it. That meant
the action expert was conditioned on the full hierarchical context
(closer to π0.7 §V.A), not just the subtask.
The π0.5 paper's hierarchical inference has the action expert see
only the *subtask* (plus images and state). Split the recipe to
match:
high_level_subtask (0.50)
user(task + plan + memory) → assistant(subtask)
[+ assistant(new_memory) at boundary frames]
All ``stream: high_level`` → text-CE only, no flow loss.
low_level_execution (0.30)
user(subtask) → assistant(subtask)
Both ``stream: low_level`` → flow loss fires; text CE on the
subtask is a small redundant extra signal. Prefix the action
expert sees: [images, subtask, state].
plan_generation (0.10) — unchanged.
ask_vqa_{top,wrist} (0.05 each) — unchanged.
Runtime: the low-level loop in ``smolvla2/inference/steps.py``
now sends ``[user(subtask), assistant(subtask)]`` to
``predict_action_chunk`` instead of the full task+plan+memory
context. Falls back to ``state['task']`` when no subtask has been
generated yet so the first frame still has something to condition
on.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>