Bilig

Bilig runs the formula-recalculation model of a workbook inside a Node.js service, test suite, or AI agent, without driving Excel or a browser grid: a caller sets input cells, recalculates dependent formulas, reads back typed computed outputs, and persists the whole state as WorkPaper JSON that can later be restored and re-verified. A published evaluator package can prove this round trip works before a project even installs the library, editing an input cell, recalculating a summary cell, saving, restoring, and comparing the restored value against the original edit.

Its lifecycle is deliberately narrow: inputs flow into formula recalculation, then typed readback, then JSON persistence, then restore verification, with helper functions for setting one or many inputs, reading one or many outputs, displaying a sheet, and committing and verifying several edits as one atomic operation. The project is explicit that it is a headless workbook runtime, not a visual spreadsheet application or a claim of full Excel compatibility, and documents separate, explicit boundaries for XLSX import, export and risk inspection. It is intended for pricing, quote approval, payouts, forecasts and other formula-backed workflows where a service or tool, rather than a person in a spreadsheet, should own the computed state.