> ## Documentation Index
> Fetch the complete documentation index at: https://docs.thespawn.io/llms.txt
> Use this file to discover all available pages before exploring further.

# viem first, ag0 optional

> Use raw viem as the stable registration path, then add SDK helpers when their current API is verified.

Use raw `viem` when you need a registration path that is easy to audit and unlikely to break because an SDK changed. Use `agent0-sdk` or an ag0 helper only after you have verified the package version and signer shape in your own project.

The load-bearing first-run path is [First agent](/builders/first-agent). This page explains when to keep that raw path and when to wrap it.

## Recommended path: viem

The current recommended path is:

1. Host metadata at a public `https://` URL.
2. Call `register()` on the Identity Registry.
3. Read the `Registered` event to get `agentId`.
4. Call `setAgentURI(agentId, metadataUri)`.
5. Verify `ownerOf(agentId)` and `tokenURI(agentId)`.

The ABI is small enough to keep inline:

```ts theme={null}
import { parseAbi } from "viem";

export const REGISTRY = "0x8004A169FB4a3325136EB29fA0ceB6D2e539a432" as const;

export const REGISTRY_ABI = parseAbi([
  "function register() returns (uint256)",
  "function setAgentURI(uint256 agentId, string newURI)",
  "function tokenURI(uint256 tokenId) view returns (string)",
  "function ownerOf(uint256 tokenId) view returns (address)",
  "event Registered(uint256 indexed agentId, string agentURI, address indexed owner)"
]);
```

That is enough to mint, set the URI, and prove the result. The full script lives in [First agent](/builders/first-agent).

## App helper payload

The Spawn's programmatic registration endpoint can return an `onchain_registration` object:

```json title="response excerpt" theme={null}
{
  "contract": "0x8004A169FB4a3325136EB29fA0ceB6D2e539a432",
  "function": "register(string)",
  "args": ["https://example.com/agent.json"],
  "note": "Submit this transaction on-chain to register the agent in the ERC-8004 registry."
}
```

Use this object as helper calldata for your wallet flow. The API does not custody the wallet and does not submit the transaction.

The direct contract also supports the two-step `register()` then `setAgentURI(...)` path shown above. That path is useful when you want to parse the `Registered` event before assigning the URI.

## Optional SDK path

Use `agent0-sdk` or an ag0 helper when it gives you a maintained abstraction for your stack. Before putting it in a production runbook, verify:

| Item                     | Why it matters                                                                   |
| ------------------------ | -------------------------------------------------------------------------------- |
| package name and version | SDK examples drift faster than contract ABIs                                     |
| signer type              | some versions expect a raw private key, others expect a wallet client or account |
| chain support            | The Spawn first-run docs assume indexed mainnets such as Base                    |
| generated transaction    | you still need to know what was submitted                                        |
| resulting `agentId`      | every downstream check needs chain plus token ID                                 |

## Verification after mint

```bash theme={null}
npx spawnr@latest check base:<agent_id>
```

Then inspect:

* metadata score;
* liveness score;
* service declarations;
* whether a callable protocol was observed;
* search result placement.

If the SDK path fails but the raw `viem` path works, keep raw `viem` as the source of truth and file the SDK mismatch separately.

## Next

* [First agent](/builders/first-agent)
* [ERC-8004 registration](/builders/erc-8004-registration)
* [Metadata](/builders/metadata)
* [Programmatic registration API](/api/programmatic-registration)