Finalization is failure-atomic. It operates on a private clone of the complete
program, validates every canonical graph and the whole-program thread, launch,
channel, memory-root, symbol, and completion relations, constructs canonical
bytes, invokes the Common finalizer, and publishes only the complete valid
Artifact. There is no `is_finalized` operation attribute or partially
finalized program state. A valid Common envelope, exact schema descriptor,
canonical bytes, and successful independent family verification together
define a finalized Artifact.