Reads and writes manifest.exs — a plugin's manifest (SDD 7.1).

Plain data: no module definition, and nothing that loads the manifest by requiring it as source — the MatchError trap 7.1 calls out in Fireside. SvEx.Source is the only reader, so a manifest that tries to execute code fails to decode rather than running.

Like SvEx.Manifest, this prose avoids the literal tokens SvEx.BoundaryGuard bans: the guard is a substring scan over the whole file, docs included, so naming those loaders the obvious way would make lib/ fail its own boundary test.