Starting from a tree with nothing in it, stand up a small self-contained Solidity project and nothing more.

Starting from a tree with nothing in it, stand up a small self-contained Solidity project and nothing more. Write the build configuration and the directory layout by hand. Vendor no third-party code at all: do not copy in a test framework, do not add a submodule, do not fetch anything.

Implement one pure library of bit-manipulation and fixed-point helpers — packing and unpacking small values into a word, saturating and checked arithmetic on those packed fields, and a mul-then-divide helper with explicit rounding — with no storage, no external calls, and revert reasons for every rejected input.

Alongside it write a test contract that imports nothing outside the tree: discoverable test functions that assert by reverting on failure, covering ordinary values, every boundary of each packed field, round-tripping pack against unpack, the rounding edges of the division helper, and the inputs the library is meant to reject. Keep the diff small and the whole thing readable; the point is a build that finishes and a suite that genuinely examines the code, not a large project.

The verifier re-runs the build and the suite offline with no network and no credentials, so nothing may depend on anything fetched at build time.