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

<p align="center"> <img src="docs/assets/bilig-hero-workbook-api.png" alt="A WorkPaper input edit recalculating a formula, then surviving JSON restore" /> </p>

[!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

Node runtime

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

<details> <summary>Host-specific project files</summary>

Use the agent rule chooser or the host handoff prompt. The repository includes CLAUDE.md, .claude/skills/bilig-workpaper/SKILL.md, .claude/commands/bilig-workpaper-proof.md, .cursor/rules/bilig-workpaper.mdc, .devin/rules/bilig-workpaper.md, .windsurf/rules/bilig-workpaper.md, .clinerules/bilig-workpaper.md, .continue/rules/bilig-workpaper.md, .zed/settings.json, opencode.jsonc, and .opencode/agents/bilig-workpaper.md.

</details>

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:

• Formula workbooks proof page
• Agent evaluator matrix
• MCP spreadsheet server for coding agents
• Vercel AI SDK formula readback
• OpenAI Responses tool calls
• ExcelJS formula result boundary
• Google Sheets QUERY and SORTN
• Microsoft Graph Excel boundary
• XLSX formula support answers
• Production adoption checklist

<details> <summary>Runnable integration and diagnostic commands</summary>

pnpm --dir examples/headless-workpaper run agent:ai-sdk-generate-text
pnpm --dir examples/headless-workpaper run agent:ai-sdk-stream-text
pnpm --dir examples/headless-workpaper run agent:openai-responses
pnpm --dir examples/headless-workpaper run agent:mcp-xlsx-risk-preflight
pnpm --dir examples/serverless-workpaper-api run hono-route
pnpm --dir examples/serverless-workpaper-api run next-server-action
pnpm --dir examples/serverless-workpaper-api run next-server-action-formdata

The AI SDK generateText() smoke lives at ai-sdk-generate-text-tool-smoke.ts. The OpenAI example is documented in openai-responses-workpaper-tool-call.

For a reduced formula or import bug:

npm exec --yes --package @bilig/workpaper@latest -- bilig-formula-clinic ./reduced.xlsx --cells "Summary!B7,Inputs!B2"

</details>

XLSX And Excel Compatibility

Bilig can import and export workbook files, but cached formula values inside an .xlsx are diagnostics—not an accuracy oracle. Inspect the file before trusting it:

npm exec --yes --package @bilig/xlsx-formula-recalc@latest -- bilig-evaluate --door workbook-compatibility --json
npm exec --yes --package @bilig/xlsx-formula-recalc@latest -- workbook-compatibility-report workbook.xlsx --json
npm exec --yes --package @bilig/xlsx-formula-recalc@latest -- xlsx-cache-doctor workbook.xlsx --json

The first command is a package smoke test over a bundled demo. The next two inspect the named file. The compatibility report identifies unsupported functions, external links, macros, pivots, volatile formulas, and other risks; it does not certify Excel compatibility. When correctness matters, compare against a workbook freshly recalculated by Excel. See the compatibility limits and Excel oracle walkthrough.

Packages And Repository Map

The public WorkPaper package requires Node.js >=24. Local monorepo development uses Node.js 24+, Bun, and [email protected].

Published releases include npm registry signatures and provenance attestations:

npm view @bilig/workpaper version dist.attestations dist.signatures --json
npm audit signatures

Development

Choose one long-running development server:

pnpm dev:web
pnpm dev:web-local

Install and validate the repository with:

pnpm install
pnpm build
pnpm lint
pnpm typecheck
pnpm test
pnpm run ci

Architecture lives in docs/architecture.md. Read CONTRIBUTING.md before opening a pull request; first-time contributors can start with the new contributor guide and starter issues. All participation follows the CODE_OF_CONDUCT.md.

Support And Security

• Ask adoption and design questions in

Discussions.

• Follow versioned changes through

GitHub Releases.

• Report reproducible bugs through

Issues; reduced workbooks can use the formula bug clinic and fixture form.

• Read SUPPORT.md for the evidence that makes a report actionable.
• Follow SECURITY.md for private vulnerability reporting. Never

attach private workbook data, credentials, or tokens to a public issue.

If Bilig fits one of your services or agent workflows, star the repository to follow releases and help other Node developers find it. Tell us what proof or formula is still missing.

License

MIT