@ar-agents/constancia

ARCA (ex-AFIP) Constancia de Inscripción — the official fiscal document, including the PDF — as a typed tool for AI agents on the Vercel AI SDK 6.

pnpm add @ar-agents/constancia ai zod

Part of the Arg toolkit — open infrastructure for the Argentine AI agent jurisdiction.

Why this exists

Every alta-de-proveedor, KYC, expediente, and licitación flow in Argentina asks for the Constancia de Inscripción: the stamped ARCA document that states a CUIT's régimen (monotributo + categoría / responsable inscripto / exento), domicilio fiscal, actividades and impuestos.

@ar-agents/identity's lookup_cuit_afip returns the data via the SOAP padrón webservice — but it needs an X.509 cert, and it can never return the PDF document. There is no API for the PDF. The only source is a public web form (no Clave Fiscal) that renders the constancia and prints it.

This package fills that gap: it drives that form via a browser runtime and returns both the parsed fields and the official PDF with its código verificador — behind a stable, typed, testable adapter contract.

It is a deliberately quarantined browser-backed tier: the package bundles no browser and no Browserbase dependency. The runtime is injected. The pure @ar-agents/* libs stay pure.

When to use this vs @ar-agents/identity

| You need… | Use | | ---------------------------------------------------------------------- | ---------------------------------------------- | | The PDF document (KYC, expediente, alta de proveedor, licitación) | @ar-agents/constancia (only source) | | The tax data, no AFIP cert provisioned | @ar-agents/constancia (public form) | | Just the tax data, and an AFIP X.509 cert is configured | @ar-agents/identity lookup_cuit_afip (faster, no browser) | | Check digit / CUIT well-formedness | @ar-agents/identity validate_cuit |

Quick start

import { Experimental_Agent as Agent, stepCountIs } from "ai";
import {
  constanciaTools,
  BrowseSkillConstanciaFetcher,
} from "@ar-agents/constancia";

const agent = new Agent({
  model: "anthropic/claude-sonnet-4-6",
  tools: constanciaTools({
    fetcher: new BrowseSkillConstanciaFetcher({
      // Wire to however you run the `afip-constancia` skill (browse CLI,
      // a Browserbase Function, a queue worker). Must resolve with the
      // JSON the skill prints — see the skill's "Output contract".
      runSkill: (cuit) => runAfipConstanciaSkill(cuit),
    }),
  }),
  stopWhen: stepCountIs(4),
});

const { text } = await agent.generate({
  prompt:
    "Necesito la constancia de inscripción del CUIT 20-41758101-5 para el alta de proveedor. Decime el régimen y guardá el PDF.",
});

With no fetcher, the tool is safe to call and returns available: false with setup instructions (UnconfiguredConstanciaFetcher). Use MockConstanciaFetcher for tests/demos.

The companion browser skill

The runbook that actually drives the ARCA form is published as the afip-constancia skill on browserbase/skills — installable into the browse CLI, OpenClaw, or Claude Code (/plugin install browse@browserbase). One artifact, two surfaces:

• This npm package — typed, testable, programmatic. For agents on the Vercel AI SDK.
• The skill — a procedural browser runbook. For any agent driving a real browser.

They share one JSON output contract (parseSkillOutput), so the seam is documented on both sides.

Resilience model

ARCA changes the form without notice. parseSkillOutput is conservative: on a structural mismatch it throws ConstanciaError("fetcher_unexpected_response") rather than return wrong data; a "not registered" response maps to cuit_not_found. The tool itself never throws at the agent — failures come back as available: false with an actionable error.

Pin the package version. Watch the changelog. Report breakage on GitHub.

Production storage

BrowseSkillConstanciaFetcher re-runs a browser every call. Constancias change rarely — cache by CUIT (a constancia is valid for the day it was issued; most flows accept a recent one). Implement ConstanciaFetcher against your store and fall back to the browser on a miss:

class CachedConstanciaFetcher implements ConstanciaFetcher {
  constructor(private store: KV, private live: ConstanciaFetcher) {}
  async getConstancia(cuit: string) {
    return (await this.store.get(cuit)) ?? this.live.getConstancia(cuit);
  }
}

License

MIT © Nazareno Clemente