I've modified my original answer a bit to fit CA's definition of "resident."
If you're "in CA for other than a temporary or transient purpose", CA considers you a resident for tax purposes. So if you're in company-sponsored temporary housing in CA, but your purpose is not temporary or transient, you'd file as a part-year CA resident. You'd become a CA resident when you move into the company housing.
https://www.ftb.ca.gov/file/personal/residency-status/index.html
Also see: https://www.ftb.ca.gov/forms/2019/2019-1031-publication.pdf
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
