The Janiastre device is the simplest in a class of devices used to establish, in simplistic terms, whether or not “reality is real”; that is to say, whether or not one is currently located within a virtuality or other simulation space.
To do this, it makes use of the implementation details of said simulation spaces; to wit, that they are implemented on top of members of the well-documented families of Stannic-computable and quantum processors and thus their associated mathematical logics, and as such are incapable of simulating the rare types of computation that fall outside these families. A Janiastre device makes use of synthetic closed time-like curves to perform acausal logic-based hyperstannic computation impossible for any finite or quantum computational device, thus probing the limits of this logic space; while such computation should succeed in base reality, the underlying structure of a simulation space cannot support these trans-temporal operations and will result in randomized or erroneous results, or in the worst case, unbounded processing crash leading to a general reality failure.
It should be noted that a Janiastre device is not a universal ontology-verifier. While effective against simulation spaces based in commonly used simulation technologies, it is theoretically possible that a simulation space operating on a (hypothetical) fully-generalized acausal logic processor would be able to correctly simulate acausal hyperstannic computation, and in the limit, a sufficiently advanced technology could use a basement universe as a simulation space.