🧱 MetaLayer SDK

Verifiable Onchain Metadata for 0G Storage
Store, verify, and fetch file contexts directly from the blockchain.

🌐 Overview

MetaLayer provides a lightweight SDK for working with onchain-aware metadata stored on the 0G Storage Network.

It enables:

• Seamless uploading of files with verifiable Merkle roots.
• Storing & retrieving contextual metadata onchain.
• Integration with decentralized indexers.
• Easy browser & backend usage.

⚙️ Installation

npm install @searchboxlabs/[email protected]

or with Yarn:

yarn add @searchboxlabs/[email protected]

🚀 Quick Start

import MetaLayerClient from "@metalayer/metalayer";
import { NETWORKS } from "@metalayer/metalayer/dist/network";
import { Blob, Indexer } from "@0glabs/0g-ts-sdk";
import { ethers } from "ethers";
import fs from "fs/promises";

async function main() {
  const client = new MetaLayerClient();
  const indexer = new Indexer(NETWORKS.testnet.indexerUrl);

  const ctx = {
    fileType: "text",
    extension: ".txt",
    dateAdded: BigInt(Date.now()),
    encrypted: false,
    creator: "0x330cA32b71b81Ea2b1D3a5C391C5cFB6520E0A10"
  };

  const buffer = await fs.readFile("./test.txt");
  const file = {
    size: buffer.length,
    slice: (start: number, end: number) => ({
      arrayBuffer: async () => buffer.slice(start, end).buffer,
    }),
  };

  const provider = new ethers.JsonRpcProvider(NETWORKS.testnet.rpcUrl);
  const signer = new ethers.Wallet(process.env.PRIVATE_KEY!, provider);

  await client.uploadWithCtx(indexer, ctx, file, NETWORKS.testnet, signer);

  const blob = new Blob(file);
  const [tree] = await blob.merkleTree();
  const rootHash = tree?.rootHash();

  const encodedCtx = await client.getOnchainAwareCtx(rootHash, NETWORKS.testnet, signer);
  console.log(client.decodeOGFileCtx(encodedCtx));
}

main();

🧩 Smart Contract

The onchain contract powering MetaLayer lives here: 🔗 MetaLayer.sol

It defines:

• getCtx(bytes32 rootHash) view returns (bytes)
• storeCtx(bytes32 rootHash, bytes memory ctx)

This allows verified metadata retrieval from smart contracts or external SDKs.

🔗 Integration Example

You can see an example integration using this SDK here: 📂 MetaLayer Integration Code

🧠 Network Configuration

export const NETWORKS: Record<string, NetworkConfig> = {
  testnet: {
    name: 'testnet',
    rpcUrl: 'https://evmrpc-testnet.0g.ai/',       // <- change if you have a different RPC
    indexerUrl: 'https://indexer-storage-testnet-turbo.0g.ai/', // <- change to the real indexer endpoint
    explorerUrl: 'https://chainscan-galileo.0g.ai/',
    chainId: 16602,
    metaLayerAddress: `0x${"3Ca8B5e3fCD85c9960C3F8c09f0cbe6145ccdC27"}`
  },
  mainnet: {
    name: 'mainnet',
    rpcUrl: 'https://evmrpc.0g.ai/',       // <- change if you have a different RPC
    indexerUrl: 'https://indexer-storage-turbo.0g.ai/', // <- change to the real indexer endpoint
    explorerUrl: 'https://chainscan.0g.ai/',
    chainId: 16661,
    metaLayerAddress: `0x${"0xd15f8fc862d29b19d8f614c4aceb727f67986677"}`
  },
};

🛠️ Development

To build from source:

git clone https://github.com/s29papi/MetaLayer.git
cd MetaLayer
npm install
npm run build

The compiled SDK will appear under:

dist/

🤝 Contributing

Pull requests and ideas are welcome! Please open an issue before submitting large changes.

🪪 License

This project is licensed under the ISC License. See LICENSE for details.