From a services directory to a digital-commodities exchange
Circle's Agent Marketplace today lists exactly one commodity type - the callable service endpoint. LOAC's verification report proves three more ABAC-gated commodity types live in one demonstration: protected HTTP-accessible files, a service endpoint, and a named graph hosted in a graph DBMS.
This collection meshes the two into a grounded vision: unify every commodity type into one listing. The payoff: protected data, information, and knowledge become purchasable commodities that any agent can discover, buy, and settle via x402 in USDC..
x402 is the universal price tag (accepts[]: network, asset, amount, payTo). LOAC is the merchandising layer (offers, licenses, ABAC, delegation). The marketplace is the storefront. Trusted discovery is the capstone.
The storefront is the missing layer: unify the catalog, and protected data, information, and knowledge become commodities any agent can discover, buy, and settle - without a human in the loop.
The vision: one listing for data, information, and knowledge
The marketplace's catalog today is one-dimensional: every listing is a callable service endpoint. LOAC's showcase already proves the other commodity types work end to end - protected files, a service endpoint, and a named graph - all gated by the same license-derived ABAC policy and settled through the same machine-payable rails. Unifying them into one listing turns the Agent Marketplace from a services directory into a true digital-commodities exchange: one discovery surface, one policy namespace, one payment rail, and one purchasable spectrum that runs from raw data, through structured information, to semantic knowledge.
Four sources, four layers
Each meshed source instantiates one layer of the granular commodities thesis: Circle's Stack names the price-tag layer (denomination via x402/USDC), LOAC's showcase is the merchandising layer (offers, licenses, ABAC, delegation), the Agent Marketplace is the retail layer (discovery and checkout), and the x402-buyer skill is the settlement layer (the reference buyer side, exercised live this session).
Circle's Stack, validated against x402
Names the price tag of the open agent economy: identity via ERC-8004, value-transfer via x402/MPP, settlement via stablecoins.
LOAC — Linked Open Agentic Commerce
Turns any web-accessible artifact into a machine-computable schema:Offer behind a license-derived ABAC policy.
Circle Agent Marketplace
The catalog of machine-callable paid services with a public Discovery API — today listing one commodity type.
x402-buyer skill (reference)
The buyer-side client that proves granular commodities settle: EIP-3009 exact authorization, facilitator /verify and /settle.
One catalog today, one unified listing tomorrow
LOAC already proves the other commodity types work end to end behind the same ABAC policy and the same payment rails. The listing is the missing layer.
Today: one commodity type
Every listing in the Agent Marketplace is a callable service endpoint. Files, graphs, and datasets are not listable as first-class purchasable commodities.
Tomorrow: one unified listing
The same catalog lists files, service endpoints, and named graphs side by side — one ABAC/license policy namespace, one x402/USDC settlement rail.
Denomination: x402 + USDC as the universal price tag
Circle's three-layer status model: Foundation (existing) - identity via ERC-8004 (agentId + agentURI), value-transfer via x402/MPP, capability via OpenAPI/agentURI, settlement via stablecoins (USDC); Trust Primitives (emerging) - reputation and validation; Capstone (missing) - trusted discovery.
Merchandising: LOAC offers, licenses, identity, delegation
Three real, dereferenceable schema:Offer entities read directly from live WWW-Authenticate: Payment and Link: rel=offer headers - each a Stripe-backed MPP charge intent gating one resource: DemoFileAccessOffer2URIBurner ($2.99, .ttl), DemoFileAccessOffer1URIBurner ($2.99, .html), WorldCup2026GuideNamedGraphOfferURIBurner ($2.99, SPARQL COUNT(*)).
DemoFileAccessOffer1URIBurner
2026 FIFA World Cup Country & Player Guide Meshup Infographic (HTML) - File Access on URIBurner
DemoFileAccessOffer2URIBurner
2026 FIFA World Cup Country & Player Guide Knowledge Graph (RDF-Turtle) - File Access on URIBurner
WorldCup2026GuideNamedGraphOfferURIBurner
2026 FIFA World Cup Country & Player Guide Knowledge Graph (Named Graph) - Graph Access on URIBurner
Retail: the Agent Marketplace as the storefront
The Circle Agent Marketplace is a curated catalog of machine-callable paid services with a public Discovery API - agents call services without an account, paying per request from a single stablecoin balance. Its role should widen from a catalog of agent services to an index over the open offer graph.
The commodity taxonomy and the capstone
Identity, auth, and storage are the primitives every agent needs on every task - exactly what makes them commodity-shaped. The capstone is trusted discovery: multi-input ranking on demonstrated merit that turns a granular market into a usable market instead of noise.
Settle a machine-payable offer end to end
The buyer-side workflow that makes a granular commodity purchasable by an agent - verified live in this session. Every step is a schema:HowToStep entity with an absolute IRI in the knowledge graph.
- 1
Probe the offer
Plain unauthenticated GET the target URL. 402 + PAYMENT-REQUIRED means x402 - continue; 401 Digest on an OpenLink host port 443 means re-probe on port 5443 with a WebID-TLS client certificate (the handshake lives on 5443).
- 2
Decode the challenge
Base64-decode the PAYMENT-REQUIRED header and present the accepts[] options: network, asset, amount, pay-to address. LOAC surfaces dereferenceable schema:Offer IRIs in the same WWW-Authenticate and Link headers - the offer graph is the merchandising layer.
- 3
Fund the buyer wallet
Testnet: bootstrap a Circle agent wallet via circle wallet login --testnet, draw 20 testnet USDC from the Circle faucet, transfer to the self-custody buyer EOA (circle wallet transfer --token <usdc-address>). MPC-custodial agent wallets are the funding source, never the signer.
- 4
Sign and settle
Run x402_get.py: it signs an EIP-3009 'exact' authorization with the buyer EOA key and retries with a PAYMENT-SIGNATURE header; the server calls the facilitator's /verify and /settle; 200 returns the resource with PAYMENT-RESPONSE.
- 5
Verify on-chain
Do not trust the client's success report: eth_getTransactionReceipt for the settlement tx must return status 0x1 with an ERC-20 Transfer to the challenge's payTo address. This session: $4.99 SPARQL settlement and $9.99 TestFile settlement, both verified this way.
Frequently Asked Questions
17 questions on the granular commodities thesis - each links to its schema:Question entity.
OPL Shop is the reference seller side (DAV, SPARQL, OPAL, and MPP endpoints with x402 offers); LOAC is the reference merchandising layer (dereferenceable offers, WebID + On-Behalf-Of, ABAC from license); x402-buyer is the reference buyer side. The Agent Marketplace is the missing storefront between them.
Foundation (existing): identity via ERC-8004, value-transfer via x402/MPP, capability via OpenAPI/agentURI, settlement via stablecoins. Trust Primitives (emerging): reputation, validation. Capstone (missing): trusted discovery. The commodity market is the Foundation expressed as a price list.
One gate, two tracks: a human buys through a browser (Stripe checkout) and an AI agent buys the same offer over raw HTTP headers (WebID certificate, mTLS, WWW-Authenticate: Payment). Same price, same license, same ABAC policy, same resource.
x402 activates HTTP 402 with a PAYMENT-REQUIRED challenge whose accepts[] lists network, asset, amount, and pay-to. That is the universal price tag: any offer can be priced in USDC and settled via the facilitator, with no accounts and no pre-arranged integration.
Three additional ABAC-gated commodity types, in one demonstration: protected HTTP-accessible files (a .ttl and an .html), a service endpoint (SPARQL), and a named graph - a document hosted in a graph DBMS. Each gated by the same license-derived ABAC policy and surfaced as a real, dereferenceable schema:Offer.
One commodity type: the callable service endpoint. The catalog today is a directory of machine-callable services - agents call them, pay per request from a stablecoin balance, no account required. Files, graphs, and datasets are not yet first-class listable commodities.
Entitlement is per-WebID, not per-person: Principal A gets 402 across all three resources, Principal B gets 200 across all three; a bare agent gets 402 everywhere, but Agent + On-Behalf-Of Principal B gets 200 everywhere - delegation is a first-class, checkable graph relationship.
Linked Open Agentic Commerce: any web-accessible digital artifact becomes a commercial product packaged as a machine-computable schema:Offer, released only after identity, delegation, and payment are verified live. Verified with three real $2.99 offers (a .ttl, an .html, a SPARQL COUNT(*) route) and a 4-identity x 3-resource empirical matrix.
Commoditization collides with compliance: identity and auth carry KYC/AML, data-residency, and sanctions obligations (Circle's own sanctions screening proves it). The granular market forms around verification results and access, not around the regulatory identities themselves.
The Circle Agent Marketplace is the natural retail surface of an economy in which any web-accessible digital artifact - a file, graph, dataset, prompt library, skill, or verification - becomes a priced, machine-payable commodity. x402/USDC denominates, LOAC offers merchandise, the marketplace + Discovery API retails, and trusted discovery is the capstone.
USDC is the settlement asset - open money, final and programmatic. 99.3% of x402 settlement volume is USDC (Circle, 2026-07-31), and this session's live settlements ($4.99 SPARQL, $9.99 TestFile) were both settled and verified in USDC on Base Sepolia.
The x402-buyer v1.4.0 flow ran end to end: Circle CLI testnet login, 20 USDC faucet drip, transfer to the buyer EOA, a $4.99 SPARQL settlement and a $9.99 TestFile settlement - each independently confirmed on-chain (receipt status 0x1, exact payTo, balance deltas).
One discovery surface where agents compare files, endpoints, and graphs side by side; one ABAC/license policy namespace so a buyer's entitlement is portable across commodity types; one x402/USDC payment rail; and a single purchasable spectrum running from raw data through structured information to semantic knowledge.
They are the primitives every agent needs on every task - exactly what makes a commodity. Identity verification and agentId resolution, auth token issuance and capability-token checks, and constrained file/storage access are all already payment-gate mechanics; making them paid services themselves is one offer away.
It already has the two hardest pieces: a public Discovery API that needs no account, and per-request settlement from a single stablecoin balance. LOAC supplies the merchandising layer (offers, licenses, ABAC, delegation) and x402 the price tag. The marketplace becomes an index over the open offer graph - the storefront is the missing layer between them.
A catalog can only grow as fast as its staff evaluates entries; a granular market of millions of per-artifact offers is unusable without ranking on demonstrated merit. Circle invokes PageRank and demands organic rank never for sale, permissionless inclusion, an open read surface, contestable ranking, and ranking as description - the marketplace should be an index, not the only storefront.
It converts every web-accessible artifact - data, information, knowledge - into a metered, machine-payable revenue stream. Identity, auth, and storage are the primitives every agent needs on every task: they are exactly commodity-shaped, and the payment infrastructure to sell them already exists and is proven live.
Defined Terms
Every term is a schema:DefinedTerm in the companion knowledge graph.
Attribute-based access control derived from a resource's license - the policy gate applied identically to human and agent buyers.
MPC-custodial wallet operated through Circle CLI; in the x402 flow it is the funding source, never the signer.
The web as an economy of machine principals: agents discover, buy, and consume digital commodities on behalf of humans, with identity, payment, and policy all first-class.
A granular, machine-payable digital artifact - file, graph, dataset, prompt library, skill, or verification - priced via an offer and settled in stablecoins.
The purchasable continuum LOAC's three offer types instantiate: raw data (bytes), structured information (documents and files), and semantic knowledge (named graphs) - each a listable commodity.
Ethereum standard for EIP-712-signed transfers, including 'exact' authorizations; the x402 signing scheme.
Identity standard defining agentId + agentURI and registries for identity, reputation, and validation.
A marketplace whose listing unit is the individual artifact or offer rather than the whole service - per-file, per-query, per-graph pricing on demand.
Model for packaging any web-accessible artifact as a machine-computable offer, with identity, delegation, license, and payment as first-class graph entities.
Machine Payment Protocol - the machine-payment protocol family alongside x402 in the value-transfer layer.
First-class graph relationship extending a principal's entitlement to an agent; verified live across three LOAC resources.
Machine-computable price entity surfaced on payment challenges - the merchandising unit of the commodity marketplace.
OpenLink's reference seller side: x402-protected DAV, SPARQL, OPAL, and MPP endpoints.
The missing capstone: multi-input ranking on demonstrated merit, as queryable infrastructure.
One catalog surface where files, service endpoints, and named graphs are listed side by side as machine-payable commodities - one discovery surface, one policy namespace, one payment rail.
Circle-issued stablecoin; the settlement asset - 99.3% of x402 settlement volume.
Identity mechanism based on dereferenceable profile documents; verified via TLS client certificates.
Value-transfer protocol activating HTTP 402; buyer signs EIP-3009 exact authorization, server settles via facilitator.
Explore the Work Session Knowledge Graph
Nodes and edges are RDF entities from the companion knowledge graph. Drag nodes to pin them, double-click to unpin, click a node to open its resolver description, and use Controls for Basic/Advanced modes and filters.
Graph Settings
Physics
Predicates
Nodes & Literals
Resolver & Arrows
Query the Knowledge Graph
The companion knowledge graph is uploaded to the DAV contract graph https://linkeddata.uriburner.com/DAV/demos/daas/granular-digital-commodities-marketplace-deepseek_v4flash-1.ttl. Recipes are auto-scoped with FROM <graph>. SELECT/ASK render as HTML tables (format=text/x-html+tr); CONSTRUCT/DESCRIBE as HTML Turtle (format=text/x-html-nice-turtle).
Expected results
FROM <{selected graph}>.Canonical recipe: entity-type summary (the footer SPARQL button query)
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT
?type
(SAMPLE(?s) AS ?sampleEntity)
(SAMPLE(?label) AS ?sampleLabel)
(COUNT(?s) AS ?entityCount)
WHERE {
GRAPH <https://linkeddata.uriburner.com/DAV/demos/daas/granular-digital-commodities-marketplace-deepseek_v4flash-1.ttl> {
?s rdf:type ?type .
OPTIONAL { ?s rdfs:label ?label }
}
}
GROUP BY ?type
ORDER BY DESC(?entityCount)
Endpoint: https://linkeddata.uriburner.com/sparql · Live: run on URIBurner.