Stock-Based Compensation - Stock options (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024	Dec. 31, 2023
Options
Outstanding at beginning of period (in shares)	6,317,063	4,178,194	4,178,194
Granted (in shares)	2,683,704	2,002,950
Exercised (in shares)		(362,947)
Cancelled (in shares)	(1,943,546)	(70,964)
Outstanding at end of period (in shares)	7,057,221	5,747,233	6,317,063	4,178,194
Vested at end of period (in shares)	3,288,233	2,030,376
Vested and expected to vest at end of period (in shares)	7,057,221	5,747,233
Weighted average exercise price
Outstanding at beginning of period (in dollars per share)	$ 2.97	$ 2.98	$ 2.98
Granted (in dollars per share)	0.78	2.86
Exercised (in dollars per share)		1.33
Cancelled (in dollars per share)	1.76	2.32
Outstanding at end of period (in dollars per share)	2.47	3.05	$ 2.97	$ 2.98
Vested at end of period (in dollars per share)	3.33	3.77
Vested and expected to vest at end of period (in dollars per share)	$ 2.47	$ 3.05
Weighted-average remaining contractual term and Aggregate intrinsic value
Outstanding at end of period (in years)	8 years 1 month 24 days	8 years 8 months 26 days	8 years 2 months 19 days	8 years 2 months 19 days
Vested at end of period (in years)	6 years 10 months 13 days	7 years 6 months 18 days
Vested and expected to vest at end of period (in years)	8 years 1 month 24 days	8 years 8 months 26 days
Outstanding at beginning of period (in dollars)	$ 4	$ 11	$ 11
Outstanding at end of period (in dollars)		15,641	$ 4	$ 11
Vested at end of period (in dollars)	$ 0	5,209
Vested and expected to vest at end of period (in dollars)		$ 15,641
Weighted average grant-date fair value of stock options granted	$ 0.45	$ 1.92