v3.26.1
Document And Entity Information - shares
 6 Months Ended
Jun. 30, 2026
Aug. 13, 2026
Document Information [Line Items]    
Document Quarterly Report true  
Document Type 10-Q  
Document Transition Report false  
Entity Interactive Data Current Yes  
Amendment Flag false  
Document Period End Date Jun. 30, 2026  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q2  
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 Current Reporting Status Yes  
Entity Shell Company true  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company false  
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  
City Area Code (212)  
Local Phone Number 319-7676  
Title of 12(b) Security None  
No Trading Symbol Flag true  
Entity Common Stock, Shares Outstanding   4,110,000