After far too long of a gap, I’ve finally started working on updating the default “bundle” of TeX support files used by Tectonic. — from TeXLive 2016 to TeXLive 2018.1. I’ve uploaded a candidate version to https://newton.cx/~peter/files/tlextras-2018.1dev.tar, which means that if you’re running version 0.1.9 or later you should be able to give it a spin with a command such as the following:
tectonic -w https://newton.cx/~peter/files/tlextras-2018.1dev.tar myfile.tex
If you have the chance, please give it a try and see if any problems crop up!
Furthermore, if you have a favorite package that’s been missing from the default bundle thus far, now is the time to reply here or file an issue on the tectonic-staging repository and put in a request. (Well, it’s always possible to add new packages later, but this is where my attention is at the moment.)