The toolset's own aqua: aqua as a Go library behind one binary, hermetic, with
one root of its own, a project directory of its own (.hermetic/), a controlled
environment for the library and the verifiers it runs, and a bin of links to
itself that dispatch to the tools it installs. A shell's aqua, if it has one, is
never shared with the toolset.
The design, the environment the binary exposes and the migration from the installer's aqua are in docs/design.md. The binary is installed by limen-install and run by limen's recipes.