{
  "id": "t4-merge-duplicate-contacts",
  "version": 1,
  "dataNotice": "All names, companies, emails and phone numbers in this task are fictional.",
  "input": "input.csv",
  "title": "Contact list: merge duplicate emails without losing data",
  "kind": "clean",
  "brief": "Two contact lists were combined and many people now appear twice. The owner wants one row per email address, but must not lose any information in the process.",
  "requirements": [
    "Trim spaces at the start and end of cells.",
    "Lowercase every email address.",
    "Remove exact duplicate rows.",
    "When two rows share an email address, remove the later row only if every non-empty value in it also appears in the row you keep.",
    "When two rows with the same email disagree (for example two different phone numbers or company names), keep both rows. A person has to decide those.",
    "Never merge values from one row into another."
  ],
  "deliverables": [
    "cleaned.csv — the cleaned file, same columns in the same order",
    "change-log.csv — header row,column,before,after,rule; one line per changed cell or removed row"
  ],
  "passScore": 90,
  "grader": "smartdata-clean grade t4-merge-duplicate-contacts cleaned.csv change-log.csv"
}