novox/hq ADR 0142, which decided this and was not implemented: "It is
unpacked into a directory named for its version, so it can read its own
version from its path. The stamp goes, and with it the need for a build to
know what it will be called."
The mesh's toolchain stamps no version, on purpose, so a delivered host
called itself "development build" and the mesh could not tell which host
any machine ran — which is the whole of what 087 added. A delivered host
lives at <libexec>/versions/<version>/<binary>, and that directory is the
answer.
A host placed by hand keeps its stamp, which is the honest answer for one
the mesh did not deliver, and is every machine until a delivery reaches
it. A binary sitting anywhere else is not read as a version at all.
The decision is split from the reading so a test can ask about a path
without being that binary.