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Payment rails for AI agents. Pay merchants in USDC on Base. Dual-protocol: x402 + OKX APP.
Payment rails for AI agents. Pay merchants in USDC on Base. Dual-protocol: x402 + OKX APP.
Remote endpoints: streamable-http: https://mcp.usecoal.xyz/api/mcp
Coal is a production payment infrastructure platform with significant legitimate functionality but moderate security concerns. The codebase demonstrates reasonable auth patterns (API keys and Bearer tokens) and proper separation of concerns, but several issues warrant attention: hardcoded private key exposure in environment configuration examples, missing input validation in critical payment paths, insufficient rate limiting scope, overly broad error responses that leak system details, and inadequate logging of security-critical events. Permissions are appropriate for a payment processor integrating with blockchain networks, but implementation gaps reduce defense against common payment system attacks. Supply chain analysis found 5 known vulnerabilities in dependencies (0 critical, 2 high severity).
4 files analyzed · 15 issues found
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From the project's GitHub README.
0G APAC Hackathon 2026 — Track 3: Agentic Economy
Payment infrastructure for the AI agent economy, built on 0G. Live at usecoal.xyz | API at api.usecoal.xyz
Coal by Schema Labs 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 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:
Coal uses five 0G network components. All live on 0G mainnet. See 0G-SETUP.md for the full integration guide.
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.
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.
0x24a80A3Bb16d26D4063Ecd4B2fD64C6856E25E8bCoal's agent-facing APIs use 0G Compute for AI inference on the decentralized GPU network:
broker.inference.verifyService(). Responses from sealed queries carry a verification signature from the Intel TDX + NVIDIA H100/H200 enclave they ran inside.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 bundlemerchant:memory:latest — memory pointer (storage URI + root hash + timestamp)paywall:{id}:manifest:latest — x402 paywall manifestEvery 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.
payment_confirmed, subscription_created, subscription_renewed, webhook_delivered, paywall_access_granted, receipt_anchoredflowchart 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 via Alchemy RPC</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
/pay/[slug] and /pay/checkout/[id]/console/0g| Metric | Value |
|---|---|
| Test suite | 512 tests across 33 files |
| 0G components | 5 on mainnet (Storage, Chain, Compute, KV, DA) |
| 0G contract | 0x24a80A3Bb16d26D4063Ecd4B2fD64C6856E25E8b |
| Network | Base mainnet (USDC) + 0G mainnet (chain ID 16661) |
| Live deployment | usecoal.xyz |
| API | api.usecoal.xyz |
| Live 0G health | api.usecoal.xyz/api/0g/health |
curl https://api.usecoal.xyz/api/0g/health — expect status: "ok" with storage, chain, compute, kv, and da all ok: true/verify/[session-id] to see the full 3-step 0G proof trail (Base TX → 0G Storage → 0G Chain) for any paymentcd examples/coal-react-checkout, cp .env.example .env.local, fill in your API key, npm install && npm run dev0G-SETUP.md for how to configure all 5 components from scratchCoal is not being replaced by 0G.
Coal is the payment execution and merchant operations layer.0G is the storage, proof, memory, and AI layer around it.That is the correct mental model for the repo.
coal/
├── backend/ # Next.js API app, Prisma, on-chain verification, 0G logic
│ └── lib/0g/ # All 5 0G component implementations (Storage, Chain, Compute, KV, DA)
├── frontend/ # Next.js UI app, docs site, dashboard, checkout surfaces
├── contracts/ # CoalReceiptAnchor V2 Solidity contract + Foundry project
├── packages/ # JS + React SDK surfaces
├── examples/ # Runnable integrations: React checkout, AgentKit action provider, demo-store
├── scripts/ # Deploy, sync, promotion scripts
├── 0G-SETUP.md # Full setup guide for all 5 0G components
├── DEPLOYMENT.md # Production deployment checklist
└── README.md # You are here
Two separate Next.js apps are deployed from the same repo:
The repo also includes runnable integration examples under examples:
@coal/react, including hosted checkout launch, success handling, receipt verification, and an agent-style simulation flow.If you want the quickest demo path, start with coal-react-checkout and examples/coal-react-checkout/README.md.
Coal has two auth surfaces:
x-api-key with coal_live_* keys/api/console/* routes use Privy Bearer JWTsLegacy Better Auth has been retired from runtime use.
Coal settles to the configured Base settlement token.
USDC is the fallback defaultMNEE_* environment aliases remain only as compatibility helpers24+cd backend && npm install
cd ../frontend && npm install
cd ..
cp backend/.env.example backend/.env
cp frontend/.env.example frontend/.env
Then fill in the required values in:
Important backend values:
DATABASE_URLALCHEMY_API_KEYPRIVY_APP_IDPRIVY_APP_SECRETNEXT_PUBLIC_FRONTEND_URLNEXT_PUBLIC_API_URLCRON_SECRETImportant frontend values:
NEXT_PUBLIC_API_URLNEXT_PUBLIC_PRIVY_APP_IDNEXT_PUBLIC_CHAIN_ENVNEXT_PUBLIC_COINBASE_BUNDLER_KEYcd backend
npx prisma db push
Open two terminals:
# Terminal 1
cd backend
npm run dev
# Terminal 2
cd frontend
npm run dev
Default local URLs:
http://localhost:3000http://localhost:3001cd backend
npm run typecheck
npm test
npm run build
cd frontend
npm run typecheck
npm run build
cd backend
npm run 0g:storage:benchmark
0G is opt-in. Coal still works without it.
For complete setup instructions for all 5 components (Storage, Chain, Compute, KV, DA), see 0G-SETUP.md.
Minimum environment variables to enable 0G:
# Storage + Chain
ZERO_G_ENABLED=true
ZERO_G_CHAIN_RPC_URL=https://evmrpc.0g.ai
ZERO_G_CHAIN_PRIVATE_KEY=0x...
ZERO_G_RECEIPT_ANCHOR_ADDRESS=0x24a80A3Bb16d26D4063Ecd4B2fD64C6856E25E8b
ZERO_G_STORAGE_INDEXER_URL=https://indexer-storage-turbo.0g.ai
ZERO_G_STORAGE_ENCRYPTION_KEY=<32-byte hex>
# Compute
ZERO_G_COMPUTE_ENABLED=true
ZERO_G_COMPUTE_PROVIDER=<provider_address>
ZERO_G_COMPUTE_BASE_URL=<provider_base_url>
ZERO_G_COMPUTE_API_KEY=<api_key>
ZERO_G_COMPUTE_MODEL=<model_name>
ZERO_G_SEALED_INFERENCE_ENABLED=true
# KV
ZERO_G_STORAGE_STREAM_ID=0x<64-hex-chars>
# DA (requires running a sidecar — see 0G-SETUP.md)
ZERO_G_DA_ENABLED=true
ZERO_G_DA_GRPC_URL=<sidecar_host>:51001
ZERO_G_DA_GRPC_TLS=false
The main implementation lives in:
backend/lib/0g/storage.ts — Storage + KVbackend/lib/0g/chain.ts — Chain anchor writesbackend/lib/0g/compute.ts — AI inference + TEE attestationbackend/lib/0g/da.ts — DA event streaming via gRPCbackend/lib/0g/merchant.ts — merchant profile + memory publishingbackend/lib/receipts/proof.ts — receipt proof pipelinecontracts/0g-receipt-anchor/src/CoalReceiptAnchor.sol — V2 contract with DASigners precompile callCanonical package surfaces:
Coal ships a docs site and a live docs playground:
http://localhost:3000/docshttp://localhost:3001/api/docs/uiKey files:
Coal deploys as two Vercel projects from the same repo:
backendfrontendUse DEPLOYMENT.md for the full production checklist.
main is production and points at Base mainnet + 0G mainnet.dev is the working branch.main.Useful scripts:
scripts/check-all.sh runs the full backend + frontend verification sweep.scripts/deploy.sh local prebuild + push to Vercel for frontend, backend, checkout, agent.scripts/push-dev.sh checks and pushes dev.scripts/promote-dev-to-main.sh fast-forwards main from dev after checks pass.MIT — Copyright (c) 2026 Schema Labs / Emmanuel Haankwenda.
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