Common stock - Stock for issuance (Details) - shares	Sep. 30, 2025	Dec. 31, 2024
Common stock
Stock options issued and outstanding under the Plans	15,695,808	11,990,781
Total reserved common stock	19,869,450	15,528,401
2020 Equity Incentive Plan
Common stock
Remaining shares available for issuance under the Plans and ESPP	2,622,783	2,631,369
ESPP
Common stock
Remaining shares available for issuance under the Plans and ESPP	1,550,859	906,251