The command line no longer imports a research module, so import-time GPU work
ends with a short-lived child instead of holding a CUDA context for the length
of a followed run. fluksio.sdk.declare starts the child, which writes each
flow's document and shims as JSON; Declared stands in for Flow in sync().
Errors keep their type and message, a child's traceback reaches the user.
Claude-Session: https://claude.ai/code/session_01SSi5AvZ7pFmySK8zy3NPMh