A container naming an artifact is a module saying the mesh builds this. Until a
build publishes one there is nothing to run — and what reached the machine was
an unresolved field, which its language has no room for, so it refused the whole
declaration and reported that a container does not use "artifact". That reads
as a broken manifest. It is not broken, it is unbuilt, and only the mesh can
tell those apart.
Found by the four-machine bed, which assigns modules the mesh has not built.