Spreadsheet Identifier Verdict

Decides whether a column of IDENTIFIERS -- order numbers, SKUs, account numbers, part numbers, barcodes, ZIP codes -- survived a trip through Excel or Google Sheets, and REFUSES TO GUESS when it cannot be known.

THE SILENT FAILURE. An identifier column goes through a spreadsheet on its way between two systems: someone opens a CSV export in Excel to eyeball it, or a report gets round-tripped through Google Sheets. It comes back LOOKING COMPLETELY FINE. No error, no red cell, no warning dialog. It is just wrong, in ways that are individually well known but badly under-documented at the point where a developer would actually go looking for a fix.

A leading zero is gone, because the column was read as a number. A long numeric identifier has become scientific notation, or has had its final digits replaced with zeros because it exceeded the precision a float can hold. Something that looked like a date became one. Every one of those is a valid cell value, so nothing downstream objects -- the identifier simply no longer matches the record it names.

IT REFUSES rather than guessing. Some corruptions are indistinguishable from legitimate data: a value that is genuinely a number and a value that WAS an identifier and is now a number look identical in isolation. Those return NOT DETERMINABLE naming the fact that would settle it, because a confident wrong answer here re-corrupts the column in the name of repairing it.

VERIFIED: 92 tests, measured by running the suite.

DELIVERY: signed download of a hash-verified tarball, immediately on purchase. Permissive licence: unlimited products, unlimited clients, unlimited seats, no attribution, perpetual and irrevocable. One restriction, do not republish the source as source.

Interface

What you call, and what comes back. Types and signatures only — the implementation ships with the source.

  export function looksLikeDateFormat(numberFormat: string): boolean;
  export function detectDateAutocorrect(cells: NormalizedCell[]): Finding[];
  export function detectLeadingZeroLoss( cells: NormalizedCell[], minPaddedSiblings: number, ): Finding[];
  export function detectMixedType(cells: NormalizedCell[]): Finding[];
  export function detectPrecisionCeiling(cells: NormalizedCell[]): Finding[];
  export function detectUnverifiableLongNumericString(cells: NormalizedCell[]): Finding[];
  export function detectScientificNotation(cells: NormalizedCell[]): Finding[];
  export function normalizeCell(input: CellInput): NormalizedCell;
  export function inferredType(cell: NormalizedCell): CellType | "null";
  export function effectiveType(cell: NormalizedCell): CellType | "null";
  export function verdictColumn( cells: readonly CellInput[], options: VerdictColumnOptions = {}, ): ColumnVerdict;

  export type CellPrimitive = number | string | boolean | Date | null | undefined;
  export type CellType = "number" | "string" | "boolean" | "date" | "error" | "unknown";
  export type CellInput = SpreadsheetCell | CellPrimitive;
  export type ColumnStatus = "INTACT" | "CORRUPTED" | "UNKNOWN";