回复：L1签证转H1B问题.

1. Assuming L1 I797 is still unexpired, L1 status ends after the last day of employment with the L1 sponsor. you should keep the last paystub to prove it.
2. If layoff comes after H1 approval, you may have a H1 I94 with start date in Oct 1 already, generally, you are fine, but I do suggest in the future take a vacation abroad and get a H1 visa stamp and re-enter, so that your can say you have not been out-of-status since that future last entry.
3. out of status for over 180 days will make you ineligible for filing I485 AOS in US under EB categories.