Skip to main content

Key Components

In this section, we'll explore the main components of the quickstart template to understand how to develop a Shade Agent. We'll also look at how to modify the template to build an agent for your use case.

Template Structure​

The template we're using is a simple Shade Agent built with Hono and written in TypeScript that acts as a verifiable ETH price oracle. It takes prices from two different APIs, takes the average, and then pushes the price to an Ethereum contract. The template also comes with a frontend to make it easier to interact with the Shade Agent.

The project has three different APIs:

  1. agentAccount - This API simply fetches the agent's NEAR account ID and its balance by using the agentAccountId and agent("getBalance") functions from the shade-agent-js library.
  2. ethAccount - This API returns the Ethereum Sepolia account that the Shade Agent uses to update the price of Ethereum in the Sepolia contract. This API is used so the user knows which account to fund for gas.
  3. transaction - This is where the core logic of the agent is defined. When this API is called, the agent will build and sign a transaction. We'll look deeper into this API route in the next part.

Signing Transactions​

In the transaction API Route, the requestSignature function from the shade-agent-js library is used to sign a transaction.

In this example, we're signing a transaction to call an Ethereum contract to update the stored price of ETH. First, we retrieve the price of ETH (in this example, the function queries two different APIs and calculates the average).

Next, we build the transaction payload to be signed. To do this, we're using the chainsig.js library. Using this library, we:

  1. Derive the Ethereum address that will be sending the transaction. This function takes the agent contract account ID since this is the predecessor account that is calling the Chain Signatures MPC contract, and a path. The path can be whatever string you like, different paths will derive different addresses.
  2. Create the data. This is what action we're performing, in this case, a function call to update the price in the contract.
  3. Build the transaction and the transaction payload by inputting the derived address, the target Ethereum smart contract, and the data.

Once we have the payload (also known as the hash), we can call the requestSignature function to sign the transaction. We specify the keyType as Ecdsa as we're signing for a blockchain that uses the secp256k1 signature scheme.

The result is the signature.

We then attach the signature to the Ethereum transaction and broadcast it to the target network.

Using Different Chains​

We set up a chain adapter for Ethereum Sepolia in the Ethereum.ts file using the chainsig.js library. This library allows us to easily construct transaction payloads to be signed by the agent.

You can set up chain adapters for a variety of chains, including EVM, Bitcoin, NEAR, Solana, SUI, XRP, Cosmos, and more to allow your agent to interact with multiple different chains. You can see a full list of the chains currently supported here, but feel free to contribute any chain that is not yet supported.

Implementation details differ slightly from chain to chain; as such, we recommend you review our chain signature docs. Note that step 3 of requesting a signature is different; we use the requestSignature function from shade-agent-js.

If you are using a chain that uses the ed25519 signature scheme (NEAR, Solana, SUI, Aptos, etc.), you should specify the keyType as Eddsa when calling requestSignature.

Next Steps​

Now that you've explored the basics of Shade Agents, we recommend diving deeper into the framework overview to understand the core concepts needed for building production-ready Shade Agents.

Office Hours

Join our weekly 1-on-1, 15 minute sessions for personalized developer support and guidance for Chain Signatures and Shade Agents.

Book a Session
Developer Support Groups

Access async support and connect with other builders in our Telegram Communities.

Chain Signatures Group|Shade Agents Group
Reach Out

If your team is building or considering building a production application using Chain Signatures or Shade Agents, please fill our our interest form.

Chain Signatures Interest Form|Shade Agents Interest Form