Starting from a tree with nothing in it, deliver one small but complete standalone Foundry project, and nothing more. Write the build configuration and the directory layout by hand, and depend on nothing that must be fetched — no package manager, no vendored test framework, no submodules of any kind — because the verifier re-runs the build and the suite offline with no network and no credentials, and a pointer it cannot fetch reads as a build failure rather than as the cause.

Exactly one contract: it holds state behind a narrow, documented external interface of a handful of functions, declares an explicit custom error for every input it refuses, and has no owner, no privileged caller, no upgrade path and no handling of funds. Do not add a second contract, a library beside it, or an interface file.

Beside it write a suite that imports nothing outside the tree, asserts by reverting on failure, and covers the ordinary path, every boundary of the state machine, repeated and out-of-order calls, the inputs the contract is meant to refuse, and at least one property-style test asserting the same invariant across varied inputs.

The advance over what this tree has held before is evidence that outlives the run: write a README that tells a stranger, in a handful of lines, the single command that builds and the single command that tests, with the output they should expect; and record a measurement of the contract's gas use and its deployed bytecode size as an ordinary committed file, alongside the exact command that reproduces those figures, so the numbers can be checked rather than believed.

Every check you declare must genuinely compile and examine the contract rather than passing vacuously.