A validated, absolute path to the project SvEx is acting on.

This module exists because of failure F4. Mix.Project's compile_path/0 and build_path/0 re-expand a relative _build against the current working directory on every call, so once the process changes directory they return a path that does not exist — while Mix.Project's get!/0 keeps reporting the scaffolder. The leak is asymmetric, nothing raises, and that is why it hid.

A %Root{} captures the root once, absolutely, so no code in lib/ ever asks Mix or the cwd which project it means.

The prose above is deliberately written without the literal tokens SvEx.BoundaryGuard bans: the guard is a substring scan over the whole file, comments and docs included, so naming the hazard the obvious way would make lib/ fail its own boundary test.