A multi-GB docker pull ran with fully captured output -- minutes of
silence that read as a hang (user interrupted a healthy run over it).
Each mirror attempt now prints which source it is trying and how long
a hit took.
Co-Authored-By: Claude <noreply@anthropic.com>
The preflight did a bare 'docker pull' -- docker.io is slow/unreachable
from CN without luck; it now walks the same fallback chain as the SWE
prefetch (daemon mirrors -> daocloud -> 1ms.run -> baidubce -> sjtu ->
rat.dev), retagging the hit to the canonical name.
Co-Authored-By: Claude <noreply@anthropic.com>
