When a task with rec:Nd/w/m/y is checked off, a new open task is appended with the updated due date. Non-strict (rec:1m) bases the next due on today; strict (rec:+1m) bases it on the existing due date.
Pure utility with Task model, line/file parse/serialize, project/context/tag extraction, due/rec segment splitting, and toggleCompleted. Round-trip tests cover priorities, dates, tag tokens, mid-word @ guards, and blank lines.