For nearly a decade, the free preschool in the Bolinas-Stinson Union School District has been a boon for families, offering vital early-childhood education and support to working parents. Five years ago, the program expanded to guarantee every 3-year-old in the area a tuition-free seat, a rarity in public education. But with the district now bracing for tighter budgets in coming years, the program’s future is tenuous.

At a meeting last week, school board members voted…