CONDENSED CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND SHAREHOLDERS’ EQUITY (DEFICIT) (UNAUDITED) - USD ($) $ in Thousands	Total	Outstanding stock options	2018 & 2020 Warrants	2025 Warrants	Issuance of Series E Preferred Stock, net of issuance costs	Issuance of Series F Preferred Stock, net of issuance costs	Common Stock	Common Stock Outstanding stock options	Common Stock Unvested RSUs	Common Stock 2018 & 2020 Warrants	Common Stock 2025 Warrants	Treasury Stock	Additional Paid-In Capital	Additional Paid-In Capital Outstanding stock options	Additional Paid-In Capital 2018 & 2020 Warrants	Additional Paid-In Capital 2025 Warrants	Related Party Promissory Note Receivable	Accumulated Deficit	Accumulated Other Comprehensive Income
Beginning balance (in shares) at Dec. 31, 2023	734,142,041
Beginning balance at Dec. 31, 2023	$ 2,125,284
Redeemable Convertible Preferred Stock
Adjustment of preferred stock to redemption value	$ 71,368
Ending balance (in shares) at Sep. 30, 2024	734,142,041
Ending balance at Sep. 30, 2024	$ 2,196,652
Beginning balance (in shares) at Dec. 31, 2023							35,297,278
Beginning balance at Dec. 31, 2023	(2,144,950)						$ 38					$ (330)	$ 0				$ (25,701)	$ (2,119,175)	$ 218
Treasury stock, beginning balance (in shares) at Dec. 31, 2023												182,500
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	13,666												13,666
Issuance of common stock upon exercise of stock options (in share)							212,541
Issuance of common stock upon exercise of stock options	1,260												1,260
Vesting of shares from early exercised stock options (in shares)							306,000
Vesting of shares from early exercised stock options	4,956												4,956
Interest income from related party promissory notes	(561)																(561)
Adjustment of preferred stock to redemption value	(71,368)												(19,882)					(51,486)
Other comprehensive income (loss)	(13)																		(13)
Net income (loss)	(244,943)																	(244,943)
Ending balance (in shares) at Sep. 30, 2024							35,815,819
Treasury stock, ending balance (in shares) at Sep. 30, 2024												182,500
Ending balance at Sep. 30, 2024	$ (2,441,953)						$ 38					$ (330)	0				(26,262)	(2,415,604)	205
Beginning balance (in shares) at Dec. 31, 2023	734,142,041
Beginning balance at Dec. 31, 2023	$ 2,125,284
Ending balance (in shares) at Dec. 31, 2024	734,142,041
Ending balance at Dec. 31, 2024	$ 2,221,651
Beginning balance (in shares) at Dec. 31, 2023							35,297,278
Beginning balance at Dec. 31, 2023	$ (2,144,950)						$ 38					$ (330)	0				(25,701)	(2,119,175)	218
Treasury stock, beginning balance (in shares) at Dec. 31, 2023												182,500
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchases of common stock (in share)	0
Ending balance (in shares) at Dec. 31, 2024	36,504,319						35,842,319
Treasury stock, ending balance (in shares) at Dec. 31, 2024	182,500											182,500
Ending balance at Dec. 31, 2024	$ (2,498,838)						$ 38					$ (330)	0				(26,456)	(2,472,299)	210
Beginning balance (in shares) at Jun. 30, 2024	734,142,041
Beginning balance at Jun. 30, 2024	$ 2,171,991
Redeemable Convertible Preferred Stock
Adjustment of preferred stock to redemption value	$ 24,661
Ending balance (in shares) at Sep. 30, 2024	734,142,041
Ending balance at Sep. 30, 2024	$ 2,196,652
Beginning balance (in shares) at Jun. 30, 2024							35,418,384
Beginning balance at Jun. 30, 2024	(2,359,590)						$ 38					$ (330)	0				(26,073)	(2,333,550)	325
Treasury stock, beginning balance (in shares) at Jun. 30, 2024												182,500
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	4,723												4,723
Issuance of common stock upon exercise of stock options (in share)							91,435
Issuance of common stock upon exercise of stock options	657												657
Vesting of shares from early exercised stock options (in shares)							306,000
Vesting of shares from early exercised stock options	4,956												4,956
Interest income from related party promissory notes	(189)																(189)
Adjustment of preferred stock to redemption value	(24,661)												(10,336)					(14,325)
Other comprehensive income (loss)	(120)																		(120)
Net income (loss)	(67,729)																	(67,729)
Ending balance (in shares) at Sep. 30, 2024							35,815,819
Treasury stock, ending balance (in shares) at Sep. 30, 2024												182,500
Ending balance at Sep. 30, 2024	$ (2,441,953)						$ 38					$ (330)	0				(26,262)	(2,415,604)	205
Beginning balance (in shares) at Dec. 31, 2024	734,142,041
Beginning balance at Dec. 31, 2024	$ 2,221,651
Redeemable Convertible Preferred Stock
Issuance of preferred stock, net of issuance costs (in shares)					12,345,674	4,657,401
Issuance of preferred stock, net of issuance costs					$ 57,217	$ 21,617
Adjustment of preferred stock to redemption value	$ 85,433
Conversion of preferred stock to common stock, including the derecognition of associated embedded derivatives (in shares)	(751,145,116)
Conversion of preferred stock to common stock, including the derecognition of associated embedded derivatives	$ (2,385,918)
Ending balance at Sep. 30, 2025	$ 0
Beginning balance (in shares) at Dec. 31, 2024	36,504,319						35,842,319
Beginning balance at Dec. 31, 2024	$ (2,498,838)						$ 38					$ (330)	0				(26,456)	(2,472,299)	210
Beginning balance, adjusted at Dec. 31, 2024	$ (2,498,837)
Treasury stock, beginning balance (in shares) at Dec. 31, 2024	182,500											182,500
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	$ 56,639												56,639
Issuance of common stock upon exercise of stock options (in share)	1,287,294						1,948,254
Issuance of common stock upon exercise of stock options	$ 3,776						$ 1						3,775
Shares withheld for taxes related to net exercise of options and settled RSUs (in shares)								(355,232)	(415,389)
Shares withheld for taxes related to net exercise of options and settled RSUs		$ (18,218)												$ (18,218)
Vesting of shares from early exercised stock options	327												327
RSU's vested upon IPO, settled in August 2025 (in shares)							1,048,250
Interest income from related party promissory notes	(128)																(128)
Payment of related party promissory notes	$ 26,584																26,584
Repurchases of common stock (in share)	(1,438,138)						(1,438,138)					(1,438,138)
Repurchases of common stock	$ (16,587)											$ (16,587)
Adjustment of preferred stock to redemption value	(85,433)												(77,084)					(8,349)
Conversion of preferred stock to common stock, including the derecognition of associated embedded derivatives (in shares)							211,378,638
Conversion of preferred stock to common stock, including the derecognition of associated embedded derivatives	2,446,004						$ 211						2,445,793
Issuance of common stock in connection with initial public offering, net of offering costs, underwriting discounts and commissions (in shares)							27,058,823
Issuance of common stock in connection with initial public offering, net of offering costs, underwriting discounts and commissions	519,452						$ 27						519,425
Net exercise of warrants in connection with initial public offering (in share)										4,174,907	784,231
Net exercise of warrants in connection with initial public offering			$ 131,746	$ 15,926						$ 4					$ 131,742	$ 15,926
Conversion of the 2025 Convertible Note, including the derecognition of associated embedded derivatives (in shares)							2,076,596
Conversion of the 2025 Convertible Note, including the derecognition of associated embedded derivatives	46,642						$ 2						46,640
Other comprehensive income (loss)	516												(22)						538
Net income (loss)	$ (150,045)																	(150,045)
Ending balance (in shares) at Sep. 30, 2025	282,103,259						282,103,259
Treasury stock, ending balance (in shares) at Sep. 30, 2025	1,620,638											1,620,638
Ending balance at Sep. 30, 2025	$ 478,364						$ 283					$ (16,917)	3,124,943				0	(2,630,693)	748
Beginning balance (in shares) at Jun. 30, 2025	0
Beginning balance at Jun. 30, 2025	$ 0
Redeemable Convertible Preferred Stock
Issuance of preferred stock, net of issuance costs					$ (276)	$ (104)
Conversion of preferred stock to common stock, including the derecognition of associated embedded derivatives	380
Ending balance at Sep. 30, 2025	0
Beginning balance (in shares) at Jun. 30, 2025							281,090,538
Beginning balance at Jun. 30, 2025	452,904						$ 282					$ (16,917)	3,123,888				0	(2,655,018)	669
Treasury stock, beginning balance (in shares) at Jun. 30, 2025												1,620,638
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	13,655												13,655
Issuance of common stock upon exercise of stock options (in share)							600,133
Issuance of common stock upon exercise of stock options	1,153						$ 1						1,152
Shares withheld for taxes related to net exercise of options and settled RSUs (in shares)								(220,273)	(415,389)
Shares withheld for taxes related to net exercise of options and settled RSUs		$ (16,152)												$ (16,152)
Vesting of shares from early exercised stock options	327												327
RSU's vested upon IPO, settled in August 2025 (in shares)							1,048,250
Conversion of preferred stock to common stock, including the derecognition of associated embedded derivatives	(380)												(380)
Net exercise of warrants in connection with initial public offering				$ (573)												$ (573)
Conversion of the 2025 Convertible Note, including the derecognition of associated embedded derivatives	3,034												3,034
Other comprehensive income (loss)	71												(8)						79
Net income (loss)	$ 24,325																	24,325
Ending balance (in shares) at Sep. 30, 2025	282,103,259						282,103,259
Treasury stock, ending balance (in shares) at Sep. 30, 2025	1,620,638											1,620,638
Ending balance at Sep. 30, 2025	$ 478,364						$ 283					$ (16,917)	$ 3,124,943				$ 0	$ (2,630,693)	$ 748