01
Install the engine for your runtime
Python, PHP, Node and the browser each install one package and need nothing compiled. The pure Python and PHP libraries have zero runtime dependencies; the native core is optional and nothing depends on it.
02
Send the smallest useful request
Ask for the smallest thing that is still real: a handful of identical cubes and one container, as JSON on stdin. Every engine accepts the same document and must return the same placements.
03
Read the answer in order
status says whether the answer is proven, the best found in the time allowed, or a refusal. containers holds the opened containers and every placement inside them. unpacked_items carries a reason per item that did not fit, and that reason, rather than the absence of a placement, is the answer to 'why not'. score ranks the result.