Starting from a tree with nothing in it, deliver one small 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.

The source tree holds exactly one contract: a modest state machine or registry behind a narrow, documented external interface of a handful of functions, declaring an explicit custom error for every input it refuses, with no owner, no privileged caller, no upgrade path and no handling of funds. Do not add a second contract, an interface file, or a helper library beside it.

In the test tree only, write a second and deliberately naive model of the same machine — the obvious, slow, plainly-correct version — and drive long randomised sequences of calls into both, comparing the full state, every count and the exact reason for every refusal after each step rather than only at the end. The advance this time is in measuring the suite rather than the contract.

Injected-fault work in this tree has so far reported that every fault was caught, which is either a strong suite or an author choosing faults already covered, and nothing distinguishes those.

So: inject faults into your own contract until you find at least one the suite as first written does NOT catch — a wrong boundary, an off-by-one in ordering, a refusal raised with the wrong reason, a stale field left unwritten — and record that miss honestly as a miss, with the fault, why the suite was blind to it, and what a caller would have observed.

Then strengthen the suite until it catches that fault, and record what you changed and why the change is general rather than tailored to that one mutation. Commit a document listing every fault attempted, whether the first suite caught it, whether the final suite catches it, and how to reproduce each result. The final suite must be green on the honest contract and red on every listed fault, and must genuinely compile and exercise the contract rather than passing vacuously.