coderai disables hf_xet by default (it bypasses the tqdm progress hook and can
segfault the worker), but some HF blobs are Xet-only and the plain HTTPS path
refuses them with "file too large … install hf_xet" — even though hf_xet is
bundled. The first pass now holds that error instead of surfacing it, detects
the Xet-required message, and transparently retries with Xet enabled
(force_xet → HF_HUB_DISABLE_XET=0). Non-Xet errors are surfaced as before; the
existing crash→disable-Xet retry is unchanged. _attempt now returns the held
error message as a 4th tuple element.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>