Coal

0G APAC Hackathon 2026 — Track 3: Agentic Economy

Payments for humans and AI agents — one checkout, real USDC on Base, verifiable receipts on 0G.

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Coal is a programmable commerce platform for hosted checkout, merchant APIs, payment links, paywalls, recurring billing, and agentic commerce flows.

Coal is built around a simple split:

• Coal handles checkout orchestration, merchant operations, payer-info capture, recurring billing, and dual-protocol agent settlement flows on Base.
• 0G adds the sidecar layer for artifact storage, receipt proof anchoring, merchant memory, and AI commerce endpoints.

This repo is an active product branch, not a tiny demo. The current codebase includes:

• hosted checkout and payment links (humans)
• dual-protocol agent payments — Coinbase x402 (v1) and OKX APP (v2) on the same /verify endpoint
• MCP server for Claude Desktop / Cursor / ChatGPT agents (multi-tenant, per-request credentials)
• merchant dashboard and onboarding
• payer-info collection at checkout
• recurring billing foundations
• widget/embed surfaces + coal-react SDK on npm
• docs site + OpenAPI playground
• demo store with verified-payment download flow
• live agent demo running on 0G Compute (Qwen)
• live 0G storage / chain / compute / KV / DA integration

0G Integration — 5 Components on Mainnet

Coal uses five 0G network components. All live on 0G mainnet. Full setup walkthrough lives on the docs site at usecoal.xyz/docs.

1. 0G Storage — Immutable Artifact Layer

Every payment receipt, merchant profile, and encrypted memory snapshot is published to 0G Storage as an immutable, content-addressed artifact. AI agents and apps can discover merchants and verify payments by reading these artifacts directly from the decentralized storage network.

• Receipt payloads: tx hash, amount, payer address, merchant, metadata
• Merchant profiles: name, products, paywalls, supported tokens, API endpoints
• Encrypted memory: AES-256-GCM encrypted full catalog + settings (only Coal can decrypt)
• Explorer: storagescan.0g.ai

2. 0G Chain — Receipt Proof Anchoring

After publishing a receipt to 0G Storage, Coal anchors a SHA-256 hash of the receipt payload on-chain via the CoalReceiptAnchor V2 smart contract. Creates a tamper-proof, independently verifiable proof that a specific payment happened at a specific time. V2 calls the DASigners precompile (epochNumber()) and embeds the current DA epoch into every anchor event.

• Contract: 0x24a80A3Bb16d26D4063Ecd4B2fD64C6856E25E8b
• Chain: 0G mainnet (chain ID 16661)
• Explorer: chainscan.0g.ai/address/0x24a80A3B...

3. 0G Compute — AI Commerce Inference

Coal's agent-facing APIs use 0G Compute for AI inference on the decentralized GPU network:

• Memory query: Natural language Q&A against merchant data ("What products does this merchant sell?")
• Commerce routing: AI decides which merchant or product fits an agent's request
• Policy evaluation: AI evaluates scenarios against merchant rules ("Can this customer get a refund?")
• Sealed Inference: Privacy-preserving inference with per-response TEE attestation via broker.inference.verifyService(). Responses from sealed queries carry a verification signature from the Intel TDX + NVIDIA H100/H200 enclave they ran inside.

4. 0G KV — Mutable Merchant Mirror

KV writes keep merchant profiles, memory pointers, and paywall manifests always-current on top of the 0G log layer, so agent discovery returns fresh data without walking the full log history.

• merchant:profile:latest — merchant profile bundle
• merchant:memory:latest — memory pointer (storage URI + root hash + timestamp)
• paywall:{id}:manifest:latest — x402 paywall manifest

5. 0G DA — Payment Event Streaming

Every confirmed payment, subscription lifecycle event, and webhook delivery is posted as a DA blob to the 0G Data Availability layer via a gRPC sidecar. External systems monitoring the DA stream see events in real time.

• 6 event types: payment_confirmed, subscription_created, subscription_renewed, webhook_delivered, paywall_access_granted, receipt_anchored
• In-memory demo feed: api.usecoal.xyz/api/0g/da-events

Architecture

flowchart TB
    subgraph Actors
        M["Merchant<br/><small>Console Dashboard</small>"]
        C["Customer<br/><small>Browser / Wallet</small>"]
        AG["AI Agent<br/><small>AgentKit / x402</small>"]
    end

    subgraph Coal["Coal Platform"]
        direction TB
        API["Console API<br/><small>Products, Links, Keys, Settings</small>"]
        CHK["Checkout Engine<br/><small>Sessions, Payments, Verification</small>"]
        PW["Paywall Gateway<br/><small>x402, Access Control, Manifests</small>"]
        RP["Receipt Publisher<br/><small>Proof Generation, Anchoring</small>"]
        ACI["Agent Commerce API<br/><small>Memory, Routing, Policy Eval</small>"]
        SUB["Subscription Engine<br/><small>Recurring Billing, Renewals</small>"]
        WH["Webhook Delivery<br/><small>Events, Retries, HMAC Signing</small>"]
        DB[("Neon Postgres")]
        AUTH["Privy Auth"]
    end

    subgraph ZG["0G Network — 5 Components Live on Mainnet"]
        direction TB
        ZGS["<b>1. 0G Storage</b><br/><small>Immutable receipt logs<br/>Merchant profiles<br/>Encrypted memory snapshots</small>"]
        ZGC["<b>2. 0G Chain</b><br/><small>CoalReceiptAnchor V2<br/>Calls DASigners precompile<br/>SHA-256 proof anchors</small>"]
        ZGX["<b>3. 0G Compute</b><br/><small>AI commerce inference<br/>Sealed Inference with TEE<br/>Per-response attestation</small>"]
        ZGK["<b>4. 0G KV</b><br/><small>Mutable merchant mirror<br/>Per-merchant stream IDs<br/>Live agent discovery</small>"]
        ZGD["<b>5. 0G DA</b><br/><small>Payment event streaming<br/>gRPC sidecar<br/>6 event types</small>"]
    end

    BASE["<b>Base (Coinbase L2)</b><br/><small>USDC settlement<br/>RPC fallback: Alchemy → mainnet.base.org</small>"]

    M -->|API| API
    C -->|Checkout| CHK
    AG -->|x402 / API| PW
    AG -->|Commerce| ACI

    RP -->|publish| ZGS
    RP -->|anchor| ZGC
    ACI -->|infer| ZGX
    API -->|mirror| ZGK
    RP -->|DA events| ZGD

    CHK --> BASE
    API --> DB
    API --> AUTH

    style Coal fill:#1a1a2e,stroke:#334155,color:#e2e8f0
    style ZG fill:#115e59,stroke:#2dd4bf,color:#ccfbf1
    style BASE fill:#1d4ed8,stroke:#60a5fa,color:#bfdbfe
    style Actors fill:#f8fafc,stroke:#cbd5e1,color:#1e293b

Agent Payments — Dual-Protocol (x402 + OKX APP)

Coal's paywall /verify endpoint accepts both payment envelopes on the same URL — Coinbase's x402 (v1) and OKX's APP (v2). The dispatch picks the right settlement path based on the header version:

• x402 v1 — Coinbase agent payment standard, EIP-3009 transferWithAuthorization on Base USDC. Gasless for the agent.
• APP v2 — OKX's agent payment whitepaper format. Same EIP-3009 wire underneath, different envelope.

Implementation:

• backend/lib/x402-settle.ts — x402 v1 settlement
• backend/lib/app-settle.ts — OKX APP v2 settlement
• backend/app/api/paywalls/[id]/verify/route.ts — version dispatch

Try the live x402 paywall on the oracle demo:

curl -i https://oracle.usecoal.xyz/api/price/ETH
# returns 402 Payment Required with the X-PAYMENT challenge

MCP Server (Claude Desktop / Cursor / ChatGPT)

Coal ships a multi-tenant MCP server at mcp.usecoal.xyz/api/mcp. 13 tools cover the full agent-commerce loop:

• discover_merchants, search_products, get_merchant_profile
• query_merchant_memory (TEE-backed natural-language Q&A)
• check_paywall, create_checkout, get_checkout_status
• verify_receipt (3-step proof trail: Base TX → 0G Storage → 0G Chain)
• get_0g_health, agent_wallet_status
• pay_merchant (USDC on Base via EIP-3009, gasless)
• download_product (verifies on-chain payment, returns signed download URL)
• setup_instructions

The server holds no long-lived secrets — every user passes their own wallet key via X-Coal-Agent-Key and their own Coal API key via X-Coal-Api-Key on each request.

// Claude Desktop config
{
  "mcpServers": {
    "coal": {
      "command": "npx",
      "args": [
        "mcp-remote",
        "https://mcp.usecoal.xyz/api/mcp",
        "--header",
        "X-Coal-Agent-Key:0xYOUR_WALLET_PRIVATE_KEY"
      ]
    }
  }
}