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Stock Incentive Plans - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended
	Jan. 31, 2026	Mar. 31, 2026	Mar. 31, 2025	Nov. 13, 2023	Sep. 30, 2018	Jun. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total (in shares)		13,076,508
Stock‑based compensation expense		$ 2,423	$ 2,508
Weighted average grant date fair value of stock options (in dollars per share)		$ 5.25	$ 14.03
Outstanding Series A Preferred Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total (in shares)		3,542,407
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting term		4 years
Weighted average period		3 years 1 month 6 days
Granted (in shares)		420,650
Granted (in dollars per share)		$ 6.76
Estimated forfeitures rate		10.00%
Unrecognized compensation expense		$ 6,400
Common stock \| Outstanding Series A Preferred Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to unvested employee stock options		$ 15,500
Weighted average period		3 years
2016 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for grants (in shares)						40,341
Number of shares authorized, increase (in shares)	1,040,444
Total (in shares)		3,044,044
Employment Inducement Incentive Award Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for grants (in shares)		502,296
Total (in shares)					39,166
Old Cartesian Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for grants (in shares)		49,149
Award vesting term		4 years
Award expiration term		10 years
Unrecognized compensation expense related to unvested employee stock options				$ 2,600
Stock‑based compensation expense		$ 100	$ 200
Old Cartesian Plan \| Old Cartestian \| Common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, options, outstanding, number (in shares)				776,865
Old Cartesian Plan \| Old Cartestian \| Preferred stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, options, outstanding, number (in shares)				14,112.299