Spreadsheet String Concatenation with Dependent Cells

Build a fixed grid with columns A through Z and rows 1 through 100. Each cell stores either a literal string or a formula that concatenates the evaluated values of other cells. If a referenced cell is changed, later get calls on cells that depend on it must observe the new value; stale cached results must never survive a set. Provide an implementation of concatenate_sheet(operations: string[][]) -> string[] that processes these operations: ["set", cell, raw] stores raw as…