Stock-Based Compensation - Schedule of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Dec. 31, 2024
Number of Shares
Beginning balance (in shares)	16,197,148
Granted (in shares)	9,543,246
Exercised (in shares)	(280,379)
Forfeited (in shares)	(1,174,166)
Expired (in shares)	(387,569)
Ending balance (in shares)	23,898,280	16,197,148
Vested and expected to vest (in shares)	23,898,280
Exercisable (in shares)	11,305,784
Weighted Average Exercise Price
Beginning balance (in USD per share)	$ 2.01
Granted (in USD per share)	0.93
Exercised (in USD per share)	0.45
Forfeited (in USD per share)	2.21
Expired (in USD per share)	2.16
Ending balance (in USD per share)	1.58	$ 2.01
Vested and expected to vest (in USD per share)	1.58
Exercisable (in USD per share)	$ 2.29
Weighted Average Remaining Contractual Life (Years)
Weighted average remaining contractual life	7 years 9 months 18 days	7 years 4 months 24 days
Weighted average remaining contractual life, vested and expected to vest	7 years 9 months 18 days
Weighted average remaining contractual life, options exercisable	6 years 3 months 18 days
Aggregate Intrinsic Value (In Thousands)
Options outstanding, beginning balance	$ 1,128
Granted, intrinsic value	3
Exercised, intrinsic value	187
Forfeited, intrinsic value	39
Expired, intrinsic value	6
Options outstanding, ending balance	12,191	$ 1,128
Vested and expected to vest, intrinsic value	12,191
Options exercisable	$ 3,641