The remote-mode seed obligation lived only in process memory
(remoteSeedPending), so a gateway restart between sandbox create and the
first exec adopted the sandbox via 'sandbox get' and silently skipped the
one-time seed, leaving an empty remote-canonical workspace with no visible
failure.
Adopted remote sandboxes now probe the managed roots once per process at
the ensure boundary and arm the seed only when every root is missing or
empty, so recovery can never wipe operator content in an already-seeded
workspace (the seed guard shipped in v2026.7.1, so legacy seeded sandboxes
without any marker exist). The probe also heals a create that timed out
client-side after the sandbox actually came up.
Regression test simulates create -> restart -> first exec and fails
pre-fix; a sibling test locks the never-reseed-non-empty-roots invariant.
Peter Steinberger
9ab6df9f19