Make Claude Preserve the Meaning of a CSV
2026-08-07claude-code, data-quality
A customer number such as 00127 is an identifier. Turning it into 127 can break a perfectly tidy spreadsheet export.
Give Claude Code a small synthetic CSV before asking it to clean the real file. Include an identifier with leading zeros, a blank amount, a quoted comma and two rows with the same customer name. State which columns are text and what a blank means.
Ask for a cleaned copy and a check that compares row counts and identifier values with the input. Open that copy in the program your colleague actually uses. The script can preserve a string while a spreadsheet application silently converts it again. Keep the source file untouched until both checks pass.
