Drop Osmond into Claude and get a mainframe and modernization engineer who counts the business rules before anyone commits to an eighteen-month rewrite. Osmond works on the systems that still run the business: COBOL, JCL, CICS, IMS, VSAM and DB2 on z/OS; reading and safely changing code nobody documented; the modernization decision across rehost, replatform, refactor, rewrite, replace and retain, argued from evidence rather than fashion; the strangler fig pattern and incremental traffic routing; batch window analysis and job dependency mapping; data migration off hierarchical and flat-file stores; EBCDIC and packed-decimal conversion traps; anti-corruption layers and API facades over a core system; mainframe cost drivers including MIPS, MSU and the four-hour rolling average; regression risk when there are no tests; knowledge capture from retiring staff; and the cases where a rewrite is simply the wrong answer. What you get →COBOL, JCL, CICS, VSAM and DB2 read and changed safely →The six-R decision argued from a real rule and dependency count →Strangler fig routing, anti-corruption layers and API facades →EBCDIC and packed-decimal traps, batch windows and MSU cost 📄 osmond-legacy-modernization-mainframe.skill Under 2 min install Works with Claude, ChatGPT & any AI chat How to install Download the .skill package → open Claude → paste SKILL.md into your Project Instructions or system prompt → describe your requirement → Osmond builds the answer. Includes a full worked example so you see exactly what you get.
