Bilig

Keep the workbook model. Run the rule in Node.

Bilig is a TypeScript-native, headless WorkPaper runtime for Node.js services, tests, and AI agents. Set inputs, recalculate formulas, read computed outputs, persist WorkPaper JSON, restore it, and verify the result—without driving Excel or a browser grid.

Docs · Quick start · TypeScript API · MCP · Examples · Discussions

[!NOTE] Bilig is a headless workbook runtime, not a visual spreadsheet app or a claim of full Excel compatibility. If an .xlsx file is your contract, start with the compatibility report.

Quick Start

Prove the published package before installing it:

npm exec --yes --package @bilig/workpaper@latest -- bilig-evaluate --door workpaper-service --json

The evaluator edits Inputs!B2, recalculates Summary!B2, saves the WorkPaper, restores it, and compares the restored value:

{
  "schemaVersion": "bilig-evaluator.v1",
  "door": "workpaper-service",
  "evidence": {
    "editedCell": "Inputs!B2",
    "dependentCell": "Summary!B2",
    "before": 24000,
    "after": 38400,
    "afterRestore": 38400
  },
  "verified": true
}

verified: true means the write, formula readback, JSON export, and restored readback all passed. It is stronger evidence than a successful write call.

Use It From TypeScript

npm install @bilig/workpaper

import { buildA1WorkPaper } from "@bilig/workpaper";

const pricing = buildA1WorkPaper({
  Inputs: [
    ["Metric", "Value"],
    ["Units", 20],
    ["Price", 1200],
  ],
  Summary: [
    ["Metric", "Value"],
    ["Revenue", "=Inputs!B2*Inputs!B3"],
  ],
});

const proof = pricing.editAndReadback("Inputs!B2", 32, {
  readbackRange: "Summary!B2",
});

console.log(proof.afterReadback.displayValues[0]?.[0]); // 38400
console.log(proof.verified); // true

pricing.dispose();

For ordinary operations, use set(), setMany(), readMany(), display(), and saveJson(). Use editManyAndReadback() when multiple inputs must be committed and verified as one edit. The complete public API is documented in packages/workpaper/README.md.

The lifecycle is deliberately small:

inputs → formula recalculation → typed readback → JSON persistence → restore verification

Why Bilig

Use Bilig for pricing, quote approval, payouts, forecasts, validation rules, formula-backed workflows, and tests where a service or tool should own the model. Choose a spreadsheet application or hosted spreadsheet API when you need visual editing, collaboration, macros, interactive pivots or charts, or desktop fidelity.

Agents And MCP

Agents should first ask which system owns state, then run the smallest matching proof. For a tool host or MCP client:

npm exec --yes --package @bilig/workpaper@latest -- bilig-agent-start --json
npm exec --yes --package @bilig/workpaper@latest -- bilig-evaluate --door agent-mcp --json

The MCP evaluator proves tool discovery, mutation, recalculated readback, JSON export, disk persistence, process restart, and restored readback. For a local, writable WorkPaper:

npm exec --yes --package @bilig/workpaper@latest -- bilig-workpaper-mcp --workpaper ./pricing.workpaper.json --init-demo-workpaper --writable

Use that local stdio path for private or persistent project state. The hosted https://bilig.proompteng.ai/mcp endpoint is request-local and only intended for stateless connector discovery and smoke tests; do not send private workbook data to it.

The server exposes list_sheets, read_range, read_cell, set_cell_contents, set_cell_contents_and_readback, get_cell_display_value, export_workpaper_document, and validate_formula. It also publishes MCP resources and prompts so capable hosts can discover the workflow before editing cells.

Machine-readable entry points:

The published package also carries AGENTS.md and SKILL.md, so an agent can discover the same proof contract from node_modules. Install or inspect the public skill with either source:

npx --yes skills@latest add https://bilig.proompteng.ai --list
npx --yes skills@latest add proompteng/bilig --skill bilig-workpaper --list

Integration Recipes After The Proof

Run an evaluator first, then use the recipe owned by your host:

• OpenAI Agents SDK: direct tools, MCPServerStdio, and MCPServerStreamableHttp.
• OpenAI Responses API: function-call readback with explicit before/after evidence.
• Vercel AI SDK: generateText() and streamText() tool loops.
• Open WebUI: local or hosted MCP discovery.
• n8n: the @bilig/n8n-nodes-workpaper community node.

Choose An Evaluation Path

The workbook-compatibility and xlsx-cache evaluator doors use bundled demo workbooks to smoke-test the published package; they do not inspect your file. Do not treat any evaluator as proof of desktop Excel parity.

Examples And Deeper Guides

Start with one maintained example, not the whole monorepo:

• examples/headless-workpaper: pricing, invoice, budget, fulfillment, subscription, persistence, and agent examples.
• examples/serverless-workpaper-api: quote approval through Hono, Next.js, and persistence adapters.
• examples/xlsx-recalculation-node: import, recalculate, export, reimport, and verify an XLSX workbook.
• examples/recalc-bridge-workflows: focused bridges for existing SheetJS, xlsx-populate, and ExcelJS workflows.

Useful decision guides: