Agent Capability Middleware

Give an AI agent permission to buy one exact x402 resource under a bounded grant—without giving the agent a wallet key.

x402 moves money; ACM governs authority.

Developer preview. The protected buyer flow is implemented and tested on Base Sepolia. Seller and data-exchange helpers are experimental local previews; they do not settle payments or prove buyer demand.

Current release: v0.1.0-preview.23.

60-second no-spend check

Requirements: Node.js 20+ and internet access. No clone, account, wallet, or private key is required.

npx --yes https://github.com/InTheta/agent-capability-middleware/archive/refs/tags/v0.1.0-preview.23.tar.gz doctor \
  > acm-no-spend-report.json

Success means the report contains:

{
  "ok": true,
  "mode": "live_no_spend",
  "canonicalRoutes": 9,
  "spent": false,
  "secretsIncluded": false
}

The check reads Coinbase's public x402 Bazaar catalog, confirms all nine canonical Omni routes, and validates the 0.003 Base Sepolia USDC quote. It creates no signature or payment.

Five-minute local demo

npx --yes https://github.com/InTheta/agent-capability-middleware/archive/refs/tags/v0.1.0-preview.23.tar.gz demo buyer

The deterministic demo creates a bounded grant, validates a fresh synthetic result, revokes the grant, and proves the next request is denied. Any 0xmock_... receipt is deliberately not a chain transaction.

Install as a dependency

npm install github:InTheta/agent-capability-middleware#v0.1.0-preview.23

import {
  AgentCapabilityClient,
  createOmniPaymentRequest,
  createOmniX402Recipe,
  requireFreshPaidResult,
} from "@agent-capability-middleware/sdk";

const acm = new AgentCapabilityClient(process.env.ACM_GATEWAY_URL!, {
  apiKey: process.env.ACM_API_KEY,
});

const recipe = createOmniX402Recipe({ kind: "market_risk", symbol: "BTC" });
const request = createOmniPaymentRequest(
  "grant_approved_by_user",
  recipe,
  crypto.randomUUID(),
);

const result = await acm.consumeX402Testnet(request);
const data = requireFreshPaidResult(result, { expectedSchema: recipe.schema });

The gateway—not the SDK or agent—holds the payer key. It checks the grant, exact URL, purpose, amount, network, asset, payee, expiry, idempotency key, approval state, and revocation state before settlement.

Controlled paid test

After an ACM operator provides a protected gateway URL and confirms its dedicated testnet payer is funded:

export ACM_GATEWAY_URL='https://provided-gateway.example'
export ACM_CONFIRM_TESTNET_SPEND=yes
npx --yes https://github.com/InTheta/agent-capability-middleware/archive/refs/tags/v0.1.0-preview.23.tar.gz partner-check \
  > acm-paid-report.json
unset ACM_API_KEY ACM_CONFIRM_TESTNET_SPEND

If that deployment requires a workload key, enter it without placing it in shell history:

printf 'ACM API key: '; IFS= read -r -s ACM_API_KEY; printf '\n'; export ACM_API_KEY

The acceptance flow buys one current BTC market-risk result, requires a fresh schema-matched response and public receipt, revokes the grant, then proves a second settlement cannot occur. Return only the redacted report. See the external developer checklist.

What you can build now

Goal	Command or guide	Status
Validate all nine live Bazaar routes without paying	acm doctor	Implemented
Inspect one live Bazaar route without paying	acm inspect	Implemented
Build exact calls across all nine Omni x402 products	acm recipes	Implemented
Buy through a protected, policy-bound payer	Getting started	Implemented on Base Sepolia
Buy a bounded Omni MCP tool through the protected payer	consumeX402McpTestnet	Implemented on Base Sepolia
Charge agents for a developer API	acm demo developer-seller	Experimental local offer helper
Offer a user-confirmed minimum-disclosure capability	acm demo user-seller	Experimental local offer helper
Compare both offer types	acm demo exchange	Experimental local directory

The nine canonical Omni templates cover targeted and market-wide AI news, exact time windows, all bounded liquidation views, all seven trader ranks, public trader-profile projections, 15/60-minute composite market risk, candles with optional liquidation overlay, current market entity resolution, and current funding/carry. acm recipes prints 25 concrete no-spend request plans over those templates; it does not claim 25 Bazaar listings.

Architecture

flowchart LR
    U["User policy"] --> G["Protected ACM gateway"]
    A["Buyer agent"] --> G
    G --> X["x402 service"]
    G -. "bounded settlement" .-> B["Base USDC"]
    G --> L["Receipt and audit"]

Loading

MCP can carry tool calls, OAuth/OIDC can identify workloads and users, verifiable credentials can carry attestations, and x402 carries payment requirements and proofs. ACM composes existing standards rather than replacing them. The protected gateway now applies the same exact grant and payment binding to four bounded Omni MCP tools.

Experimental seller previews

ACM also explores the other side of the market: a developer can describe a paid API, and a user can offer a confirmed, minimized capability under Free, Paid, Ask, or Deny policy. These helpers are useful for product design and local testing, but they are not yet hosted settlement, fulfilment, an auction, or a production data marketplace.

npx --yes https://github.com/InTheta/agent-capability-middleware/archive/refs/tags/v0.1.0-preview.23.tar.gz demo developer-seller
npx --yes https://github.com/InTheta/agent-capability-middleware/archive/refs/tags/v0.1.0-preview.23.tar.gz demo user-seller
npx --yes https://github.com/InTheta/agent-capability-middleware/archive/refs/tags/v0.1.0-preview.23.tar.gz demo exchange

See runnable examples and the user seller preview.

Verify the repository

git clone https://github.com/InTheta/agent-capability-middleware.git
cd agent-capability-middleware
npm ci
npm run verify

Verification type-checks the SDK and a consumer, runs the test suite and privacy checks, exercises the examples, packs and installs the package in a clean temporary project, and checks the CLI and fresh-developer lifecycle. CI also rebuilds the committed dist/ directory and fails if the shipped GitHub-install artifact does not exactly match the TypeScript source.

Boundaries

This repo contains the public SDK, request builders, local evidence minimizer, experimental offer helpers, examples, and tests. It does not contain private keys, a hosted vault, production identity verification, a live user-data marketplace, guaranteed user revenue, or a production fraud/risk control plane.

Documentation

• Five-minute getting started
• Runnable examples
• Omni agent recipes
• SDK API
• x402 integration
• Architecture
• Privacy-safe learning
• Security
• Roadmap

Apache-2.0 licensed.