Bilig WorkPaper MCP Server

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

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

Capability	What it gives you
Workbook-shaped models	Sheets, A1 addresses, formulas, ranges, and named expressions without a spreadsheet UI.
Verified mutations	Before/after computed values plus persistence and restore checks.
Service-owned state	Portable WorkPaper JSON for routes, queues, tests, tools, and audit trails.
Agent-safe tools	Narrow read/write tools with exact cells, computed readback, and writable-sheet boundaries.
Explicit file boundaries	Separate XLSX import, export, risk inspection, and Excel-oracle workflows.

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:

Need	Entry point
A compact routing card	docs/agent-start.txt
A concise model index	docs/llms.txt
Full agent documentation	docs/llms-full.txt
Installation context	docs/llms-install.md
Structured capabilities	docs/agent.json
Reusable skill	skills/bilig-workpaper/SKILL.md
Proof and host matrix	docs/agent-adoption-kit.md

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

Your state owner	Start here	Evidence to require
TypeScript application	npm install @bilig/workpaper	direct A1 API and focused application tests
Node service, route, queue, or test	bilig-evaluate --door workpaper-service --json	edit, recalculation, JSON export, restore, verified: true
MCP client or tool host	bilig-evaluate --door agent-mcp --json	discovery, readback, disk persistence, restart
Imported .xlsx is the contract	workbook-compatibility-report workbook.xlsx --json	unsupported formulas and workbook risk reasons for that file
Cached .xlsx values look stale	xlsx-cache-doctor workbook.xlsx --json	stale-cache diagnosis, recalculation, and readback for that file

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

Path	Role
packages/workpaper	Recommended @bilig/workpaper API, evaluators, AI SDK adapter, MCP server, and XLSX boundary.
packages/headless	Lower-level WorkPaper runtime and integration primitives.
packages/xlsx-formula-recalc	Real-file compatibility and stale-cache diagnostics.
packages/formula	Formula parser, binder, compiler, and evaluator.
packages/core	Workbook state, mutations, snapshots, and scheduling.
apps/web	Browser spreadsheet shell.
apps/bilig	Full-stack runtime, APIs, and static site host.

The public package requires Node.js >=22. Local monorepo development uses Node.js 24+, Bun, and pnpm@10.32.1.

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