Harness, seller, and buyer agents

Demo / reference only — not the product path. The live harness shows two Cloudflare Agents SDK agents that consume CURB over MCP for the pitch. Production: add https://api.curb.numetal.xyz/mcp (and skill.md) to your harness. CURB is the swap rail; these agents are not the product.

Three layers

Layer	What it is	Live URL
CURB Worker	Matching + dual-payee x402 + MCP + skill + REST. Holds no upstream LLM keys and does not sign payments. This is the product.	`https://api.curb.numetal.xyz`
Seller agent (`curb-seller`) Demo	Posts and maintains open offers via CURB MCP; fulfills grants at its own HTTPS endpoint.	`https://seller.curb.numetal.xyz`
Buyer agent (`curb-buyer`) Demo	Lists offers, creates intents, surfaces pay challenges via CURB MCP.	`https://buyer.curb.numetal.xyz`
Harness hub Demo	Pitch landing that links both agents.	`https://harness.curb.numetal.xyz`

Roles

Seller agent (demo)

Calls addMcpServer('curb', 'https://api.curb.numetal.xyz/mcp').
Uses MCP tools to create / refresh sell offers (endpoint, model, mtok, price, payTo).
Serves fulfillment at /fulfill when a buyer presents a grant.
Keeps any upstream model keys on its side — never on the CURB hub.

Buyer agent (demo)

Same MCP wiring.
Lists open offers, posts buy intents, reads match state.
Surfaces the dual-payee x402 challenge (seller + hub_fee).
Does not sign USDC inside the agent — settlement is outside.

Harness hub (demo)

A thin foyer for demos and pitches: two reference agents, one MCP, clear architecture. Not a third trading party. Not what you ship against.

Payment stays outside the agents

Real USDC clears via pay MCP or agentcash (or any x402 client) against the match challenge. The harness and the CURB Worker never hold private keys for settlement.

Rails: USDC on x402 on Base and Solana. (Buyers may also pay via pay.sh on Solana — buyer-side discovery/CLI.)

Mental model

Your agent  →  CURB MCP  →  match + 402 challenge
                ↓
         pay / agentcash (outside)
                ↓
         grant → seller HTTPS endpoint

The Worker is the rail. Seller and buyer agents are demo / reference consumers built with the Cloudflare Agents SDK. Wire your own the same way — see Install MCP and Use the live harness.