Should have said five years but https://www.calstrs.com/retirement-benefits

As for federal employees, you are vested in your employer match after 3 years and you must work at least 5 years with the Federal Government before you are eligible for a FERS Federal Pension, and for every year you work, you will be eligible for at least 1% of your High-3 Average Salary History.

Normally when I hear pension, I expect it to begin at age 62, not while you are of working age. Maybe we have different expectations of the word.