Segment - Summary of Reconciles Reported Revenues to Net (Loss) Income under Significant Expense Principle (Details) - USD ($) $ in Thousands		3 Months Ended				6 Months Ended		12 Months Ended
		Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Research and development expenses	[1]	$ 22,680		$ 15,689		$ 42,252	$ 28,193
General and administrative expenses	[2]	6,816		5,111		14,352	9,701
Loss from operations		(29,496)		(20,800)		(56,604)	(37,894)
Interest income		2,764		2,679		5,809	4,494
Change in fair value of preferred stock tranche right liability							(7,390)
Net loss		(26,732)	$ (24,063)	(18,121)	$ (22,669)	(50,795)	(40,790)	$ (78,300)
RAP-219 Program External Expenses
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Research and development expenses		9,685		4,846		17,648	8,747
Preclinical Programs External Expenses
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Research and development expenses		4,722		5,648		7,968	9,582
R & D Personnel-Related Costs (Including Stock-based Compensation)
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Research and development expenses		6,666		4,590		13,452	8,607
Other Costs
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Research and development expenses		1,607		605		3,184	1,257
G & A Personnel Related Costs (Including Stock-based Compensation)
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
General and administrative expenses		5,045		3,436		10,004	5,833
Professional and Consulting Costs
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
General and administrative expenses		920		1,108		2,584	2,973
Facility Related and Other
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
General and administrative expenses		$ 851		$ 567		$ 1,764	$ 895

[1] Includes related party amounts of zero for each of the three months ended June 30, 2025 and 2024, and zero and less than $0.1 million for the six months ended June 30, 2025 and 2024, respectively (see Note 10).

[2] Includes related party amounts of zero for each of the three months ended June 30, 2025 and 2024, and zero and $0.1 million for the six months ended June 30, 2025 and 2024, respectively (see Note 10).