build.artifacts[].env on a bundle: words and values written with ${dir:…} and ${port:…} only,
refused when a value carries any other reference (a secret's content, a binding) or names a word
the runtime sets for itself, and on any artifact that is not a bundle. Resolved per machine like a
container's environment and handed to the runtime as MESH_TOOL_ENV, module by module, in the unit
so a change restarts it. Every file and directory of the module a word names, or that holds one, is
owned by the account the runtime runs as where it says no owner, since a tool reads as that account.
jochen