v3.25.4
Cover - USD ($)
 12 Months Ended
Dec. 31, 2025
Feb. 11, 2026
Jun. 30, 2025
Document Information [Line Items]      
Document Type 10-K    
Document Annual Report true    
Document Transition Report false    
Document Financial Statement Error Correction [Flag] false    
Entity Interactive Data Current Yes    
ICFR Auditor Attestation Flag false    
Amendment Flag false    
Document Period End Date Dec. 31, 2025    
Document Fiscal Year Focus 2025    
Document Fiscal Period Focus FY    
Entity Information [Line Items]      
Entity Registrant Name ALLEGRO MERGER CORP.    
Entity Central Index Key 0001720025    
Entity File Number 001-38581    
Entity Tax Identification Number 82-2425125    
Entity Incorporation, State or Country Code DE    
Current Fiscal Year End Date --12-31    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Shell Company true    
Entity Filer Category Non-accelerated Filer    
Entity Small Business true    
Entity Emerging Growth Company false    
Entity Public Float     $ 0
Entity Incorporation, Date of Incorporation Aug. 07, 2017    
Entity Contact Personnel [Line Items]      
Entity Address, Address Line One 777 Third Avenue    
Entity Address, Address Line Two 37th Floor    
Entity Address, City or Town New York    
Entity Address, State or Province NY    
Entity Address, Postal Zip Code 10017    
Entity Phone Fax Numbers [Line Items]      
City Area Code (212)    
Local Phone Number 319-7676    
Entity Listings [Line Items]      
Entity Common Stock, Shares Outstanding   4,110,000