@ausca/ai-sdk

Vercel AI SDK tools that consume paid HTTP APIs by answering 402 Payment Required with an x402 v2 payment, instead of carrying an API key. The model authors the request; the wallet and a hard per-call USD cap stay with your code.

Works against any x402 v2 resource. Ausca is the default example because its services are keyless and receipt-backed, which is the shape this tool exists for.

Install

npm install @ausca/ai-sdk ai viem zod

Use

import { generateText } from "ai";
import { x402Tool } from "@ausca/ai-sdk";
import { privateKeyToAccount } from "viem/accounts";
import { z } from "zod";

const account = privateKeyToAccount(process.env.WALLET_PRIVATE_KEY as `0x${string}`);

const result = await generateText({
  model: yourModel,
  prompt: "Extract the text from the uploaded scan.",
  tools: {
    // Document OCR on Ausca: copy the exact offer binding from
    // https://ausca.com/catalog.json (offer document.ocr).
    extract_document_text: x402Tool({
      description:
        "Extracts normalized text from a scanned document for $0.30. Input is the immutable artifact commitment of the uploaded document.",
      inputSchema: z.object({
        artifact_ref: z.string(),
        content_digest: z.string(),
        media_type: z.string(),
      }),
      url: "https://ausca.com/v1/extract-text",
      account,
      maxPaymentUsd: 0.5,
      buildBody: (input) => ({
        offer_id: "document.ocr",
        input: { artifact: input },
        idempotency_key: `ocr-${input.content_digest.slice(7, 27)}`,
      }),
    }),
  },
});

The tool result carries the resource result and, when the call was paid, the decoded settlement proof from the PAYMENT-RESPONSE header.

Spend authority

maxPaymentUsd is enforced by the x402 client's spend controls before anything is signed. A resource quoting above the cap makes the tool throw; no payment is created. The account object never reaches the model.

Any x402 resource

Nothing here is vendor-specific: point url at any endpoint that answers an x402 v2 challenge and the tool pays it under the same cap. network defaults to Base mainnet (eip155:8453) and accepts any CAIP-2 network your account can pay on.

License

MIT