Stock-based compensation - Summary of stock option activity (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Mar. 07, 2024	Dec. 31, 2025	Dec. 31, 2024
2020 Stock Option and Incentive Plan
Number of Options
Options outstanding, beginning balance (in shares)		11,508,150
Options granted (in shares)		2,172,150
Options exercised (in shares)		(50,000)
Options forfeited/expired (in shares)		(769,813)
Options outstanding, ending balance (in shares)		12,860,487	11,508,150
Options exercisable (in shares)		9,026,492
Options vested and expected to vest (in shares)		12,860,487
Weighted-Average Exercise Price
Options outstanding, beginning balance (in dollars per share)		$ 12.00
Options granted (in dollars per share)	$ 22.00	2.92
Options exercised (in dollars per share)		2.15
Options forfeited/expired (in dollars per share)		8.99
Options outstanding, ending balance (in dollars per share)		8.26	$ 12.00
Options exercisable (in dollars per share)		9.66
Options vested and expected to vest (in dollars per share)		$ 8.26
Options, Additional Disclosures
Weighted average remaining contractual term, outstanding		6 years 4 months 20 days	7 years 8 months 12 days
Weighted average remaining contractual term, exercisable		5 years 8 months 8 days
Weighted average remaining contractual term, vested and expected to vest		6 years 4 months 20 days
Aggregate intrinsic value, outstanding		$ 156	$ 2,877
Aggregate intrinsic value, exercisable		8
Aggregate intrinsic value, vested and expected to vest		$ 156
Inducement Grants
Number of Options
Options outstanding, beginning balance (in shares)		990,360
Options granted (in shares)		0
Options exercised (in shares)		0
Options forfeited/expired (in shares)		(146,880)
Options outstanding, ending balance (in shares)		843,480	990,360
Options exercisable (in shares)		344,137
Options vested and expected to vest (in shares)		843,480
Weighted-Average Exercise Price
Options outstanding, beginning balance (in dollars per share)		$ 5.11
Options granted (in dollars per share)		0
Options exercised (in dollars per share)		0
Options forfeited/expired (in dollars per share)		6.32
Options outstanding, ending balance (in dollars per share)		4.90	$ 5.11
Options exercisable (in dollars per share)		4.52
Options vested and expected to vest (in dollars per share)		$ 4.90
Options, Additional Disclosures
Weighted average remaining contractual term, outstanding		8 years 3 months 7 days	9 years 3 months 10 days
Weighted average remaining contractual term, exercisable		8 years 25 days
Weighted average remaining contractual term, vested and expected to vest		8 years 3 months 7 days
Aggregate intrinsic value, outstanding		$ 0	$ 40
Aggregate intrinsic value, exercisable		0
Aggregate intrinsic value, vested and expected to vest		$ 0