STUB: Introduces the four parts of the ecosystem: the compiler, the runtime library, the nexus, and the environment manager (mim). Explains what each one owns, which part invokes which, and at what point in a program’s life (install, build, run, serve). Specifies the on-disk layout of an installation and names every manifest and lock file, with a sentence on each one’s role. States how versions of the parts must agree, including the ABI version check that rejects a mismatched runtime. Ends with a map linking each concern to the section that specifies it.