Consolidated Statements of Operations And Comprehensive Loss - USD ($) $ in Thousands		6 Months Ended	12 Months Ended
		Dec. 31, 2024	Dec. 31, 2025
Operating expenses:
Research and development	[1]	$ 31,234	$ 93,121
General and administrative	[2]	4,304	20,421
Total operating expenses		35,538	113,542
Total operating expenses		(35,538)	(113,542)
Other income / (expense)
Interest income		1,159	7,782
Change in fair value of convertible notes payable	[3]	(12,600)	(21,584)
Other expense		0	(8)
Total other expense, net		(11,441)	(13,810)
Net loss before income tax expense		(46,979)	(127,352)
Income tax expense		0	(58)
Net loss		(46,979)	(127,410)
Other comprehensive income (loss):
Currency translation adjustment		0	(28)
Unrealized gain on investments		0	157
Comprehensive loss		$ (46,979)	$ (127,281)
Net loss per share attributable to common stockholders, basic		$ (14.89)	$ (3.19)
Net loss per share attributable to common stockholders, diluted		$ (14.89)	$ (3.19)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic		3,155,500	31,359,958
Weighted-average shares used in computing net loss per share attributable to common stockholders, diluted		3,155,500	31,359,958
Series A Non-voting Convertible Preferred Stock
Other comprehensive income (loss):
Net loss per share attributable to common stockholders, basic		$ 0	$ (3,193.3)
Net loss per share attributable to common stockholders, diluted		$ 0	$ (3,193.3)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic		0	8,541
Weighted-average shares used in computing net loss per share attributable to common stockholders, diluted		0	8,541

[1] Includes related party amount of $28.6 million for the year ended December 31, 2025 and $24.6 million for the period from June 18, 2024 (inception) to December 31, 2024 (see Note 13).

[2] Includes related party amount of $0.3 million for the year ended December 31, 2025 and $1.0 million for the period from June 18, 2024 (inception) to December 31, 2024 (see Note 13).

[3] Includes related party amount of $4.6 million for the year ended December 31, 2025 and $2.7 million for the period from June 18, 2024 (inception) to December 31, 2024 (see Note 13).