FBR + EOBI tax engine
Property-tested salary engine for Pakistan's FBR slabs and EOBI rates. Forward Gross→Net + bisection Net→Gross solver. 17/17 vitest property tests green.
in production, no sandbox here
This one runs in Beeline Medical. It has no sandbox on this site, because the pattern only means anything against a real database, real roles, and real money. Rebuilding that as a toy would demonstrate the toy.
The write-up covers how it works and where it is deployed.