The runtime infrastructure can support all of those. The current recorded browser runs on mac, and the mac image is replayed in a linux backend (with the system calls being handled by the replay engine).

Our initial launch is with a modified Firefox browser on Mac, but the infrastructure itself is generalizable to other runtimes and other operating systems.

However, we do need to "paravirtualize" the runtimes that are recorded on our system (modify the underlying runtime to make it aware that it's being recorded, and do some integration work for each runtime). The design of our system allows for new runtimes to plug in and use all the same infrastructure for replaying.

So the long answer is that we can support them, but support for each runtime will arrive as we prioritize and complete the implementation for them.

Currently we have the mac Firefox-forked browser. In the works we have a chrome browser, nodejs backend, and a firefox fork for windows. But realistically we should be able to support `(any runtime x any os)` within reasonable bounds. Record and replay all the things :)