v3.26.1
Cover
 6 Months Ended
Jun. 30, 2026
Document Information [Line Items]  
Document Type S-1
Amendment Flag false
Entity Central Index Key 0002130606
Entity Registrant Name OBSIDIAN THERAPEUTICS, INC.
Entity Incorporation, State or Country Code DE
Entity Primary SIC Number 2834
Entity Tax Identification Number 42-1977778
Entity Address, Address Line One 1030 Massachusetts Avenue
Entity Address, City or Town Cambridge
Entity Address, State or Province MA
Entity Address, Postal Zip Code 02138
City Area Code 781
Local Phone Number 806-6245
Entity Small Business false
Entity Filer Category Non-accelerated Filer
Entity Emerging Growth Company true
Entity Ex Transition Period false
Business Contact [Member]  
Document Information [Line Items]  
Contact Personnel Name Madan Jagasia
Entity Address, Address Line One 1030 Massachusetts Avenue
Entity Address, City or Town Cambridge
Entity Address, State or Province MA
Entity Address, Postal Zip Code 02138
City Area Code 781
Local Phone Number 806-6245