Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Cash flows from operating activities:
Net loss	$ (43,438)	$ (69,167)
Adjustments to reconcile net loss to net cash used in operations:
Royalty obligation expense - related party		32,044
Depreciation expense	13
Stock-based compensation expense	1,936	895
Capital contributions - in-kind services - related party		60
Change in fair value of derivative liabilities (including $1,165 and $2,039 for a related party)	(1,229)	(2,084)
Change in fair value of tranche liability (including $331 and $19,064 for a related party)	(365)	(21,012)
Non-cash interest expense (including $1,384 and $2,656 for a related party)	1,443	2,701
Non-cash operating lease expense	53
Net amortization of premiums and accretion of discounts on marketable securities	(399)
Loss on extinguishment and on issuance of convertible promissory notes (including $169 and $34,692 for a related party)	186	38,018
Changes in assets and liabilities:
Prepaid expense and other current assets	1,810	(803)
Other non-current assets	(355)	(410)
Accounts payable	(88)	(1,027)
Accrued expenses and other current liabilities (including $16 and $0 for a related party)	2,144	115
Operating lease liabilities	(81)
Net cash used in operating activities	(38,370)	(20,670)
Cash flows from investing activities:
Purchases of short-term marketable securities	(34,523)
Maturities of short-term marketable securities	15,000
Purchase of property and equipment	(200)
Net cash used in investing activities	(19,723)
Cash flows from financing activities:
Proceeds from issuance of common stock in private placement	42,000
Proceeds from issuance of pre-funded warrants in private placement	8,000
Payment of issuance costs	(1,669)
Proceeds from the issuance of redeemable convertible preferred stock, net of issuance costs		1,591
Proceeds from the issuance of convertible promissory notes (including $3,402 and $19,041 from a related party), net of issuance costs	7,500	19,966
Cash acquired in connection with the Merger	102,113
Payment of deferred transaction costs and issuance costs	(2,937)	(2,420)
Proceeds from the exercise of stock options		3
Net cash provided by financing activities	155,007	19,140
Net increase (decrease) in cash and cash equivalents and restricted cash	96,914	(1,530)
Cash and cash equivalents and restricted cash, at beginning of the period	1,639	3,169
Cash and cash equivalents and restricted cash, at end of the period	98,553	1,639
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	98,054	1,639
Restricted cash	499
Total cash, cash equivalents and restricted cash, at end of the period	98,553	1,639
Supplemental disclosure of cash flow information:
Right-of-use assets obtained in exchange for operating lease liability	1,528
Merger transaction costs recognized in additional paid-in capital	5,357
Recognition of AlloVir common stock outstanding at the closing of the Merger	104,990
Issuance of redeemable convertible preferred stock upon conversion of convertible promissory notes	3,695
Conversion of redeemable convertible preferred stock into common stock in connection with the Merger	49,694
Conversion of convertible promissory notes and accrued interest in connection with the Merger	20,799
Deferred transaction and financing issuance costs included in accounts payable and accrued expenses and other current liabilities	1,717	748
Unrealized gain on available-for-sale securities	6
Capital contributions in-kind services related party		60
Premium on issuance of convertible promissory notes (including $169 and $15,296 for a related party)	$ 186	16,641
Repurchase of common stock shares for royalty obligation		32
Vesting Of Restricted Stock Awards		$ 1