fetch_checkpoint: fall back to VERIFY_KWARGS like the verify path - #222
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The download phase runs setup(checkpoint, "cpu") via _run_download, but unlike verify_checkpoint it never fell back to the env's declared VERIFY_KWARGS when no explicit setup_kwargs were given. Since #219 made multi-head checkpoints raise without a head selection, every such checkpoint (uma task=..., mace-mh-1 head=...) failed the sync's download phase with e.g. "download: ValueError: uma-s-1p1 is multi-task and has no default head" (first seen on the 2026-08-28 Aurora sync, 1.6.3). Resolve the hosting env first, then default setup_kwargs to verify_kwargs_for(root, env_name, checkpoint) — explicit kwargs still win, and envs without VERIFY_KWARGS still get {}. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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Problem
Found on the first Aurora sync (2026-08-28, rootstock 1.6.3): every multi-head checkpoint fails the sync's download phase with e.g.
fetch_checkpointruns the download by callingsetup(checkpoint, "cpu", **setup_kwargs)via_run_download, but defaultedsetup_kwargsto{}instead of falling back to the env's declaredVERIFY_KWARGS. Since #219 made multi-head checkpoints raise when no head is selected (uma:task=..., mace-mh-1:head=...), the bare download always raises. The verify path already falls back correctly (verify.py).Fix
Resolve the hosting env first, then default
setup_kwargstoverify_kwargs_for(root, env_name, checkpoint)— the same fallback the verify path uses. Explicit kwargs still win, and envs withoutVERIFY_KWARGSstill get{}.Regression tests added alongside the existing fetch tests in
tests/commands/test_add_split.py: the declaredVERIFY_KWARGSreach_run_download, and explicit kwargs override them.Notes
uma-s-1p1,uma-s-1p2p1,uma-m-1p1, andmace-mh-1on the aurora manifest.🤖 Generated with Claude Code