Manage session keys

Example of a session key with an action policy.

1 - Create a Session Key

When using a Permissionless account configured like in section Setup Smart Account Client, you have to skip the Safe 7579 module installation step.

This is unnecessary because the Permissionless flow automatically handles module installation during Smart Account creation via the ERC-7579 Launchpad. Including this step may lead to redundant or conflicting behavior.

SDK Core

import type { Address, PublicClient } from "viem";
import { generatePrivateKey, privateKeyToAccount } from "viem/accounts";
import {
    erc7579Actions,
    smartSessionActions,
    type SafeSigner,
} from "@cometh/session-keys";
import { isSmartAccountDeployed } from "permissionless";

export const COUNTER_CONTRACT_ADDRESS =
    "0x4FbF9EE4B2AF774D4617eAb027ac2901a41a7b5F";


const safe7559Account = smartAccountClient.extend(smartSessionActions())
            .extend(erc7579Actions());

const privateKey = generatePrivateKey();
const sessionOwner = privateKeyToAccount(privateKey);

 if (!(await isSmartAccountDeployed(
     safe7559Account?.account?.client as PublicClient, 
     safe7559Account?.account?.address as Address,
 ))) {
     safe7559Account.addSafe7579Module()
 }
        
const createSessionsResponse = await safe7559Account.grantPermission({
    sessionRequestedInfo: [
        {
            sessionPublicKey: sessionOwner.address,
            actionPoliciesInfo: [
                {
                    contractAddress: COUNTER_CONTRACT_ADDRESS,
                    functionSelector: toFunctionSelector(
                        "function count()"
                    ) as Hex,
                },
            ],
        },
    ],
});

await safe7559Account.waitForUserOperationReceipt({
    hash: createSessionsResponse.userOpHash,
});

Permissionless

2 - Store the Session Key

In our example, we will store the session key details in local storage. You are free to store it wherever you want.

import { SmartSessionMode } from "@cometh/session-keys";

const sessionData = {
    granter: safe7559Account?.account?.address as Address,
    privateKey: privateKey,
    sessionPublicKey: sessionOwner.address,
    description: `Session to increment a counter`,
    moduleData: {
        permissionIds: createSessionsResponse.permissionIds,
        action: createSessionsResponse.action,
        mode: SmartSessionMode.USE,
        sessions: createSessionsResponse.sessions,
    },
};

// This is for example purposes.
const sessionParams = stringify(sessionData);

localStorage.setItem(
    `session-key-${safe7559Account?.account?.address}`,
    sessionParams
);

3 - Use the Session Key

SDK Core

import {
    createComethPaymasterClient,
    createSmartAccountClient,
} from "@cometh/connect-core-sdk";
import {
    toSmartSessionsSigner
    smartSessionActions,
    toSmartSessionsAccount,
} from "@cometh/session-keys";
import { privateKeyToAccount } from "viem/accounts";

const bundlerUrl = process.env.4337_BUNDLER_URL;
const paymasterUrl = process.env.4337_PAYMASTER_URL

const stringifiedSessionData = localStorage.getItem(
    `session-key-${WALLETADDRESS}`
);
const sessionData = parse(stringifiedSessionData);

const sessionKeySigner = await toSmartSessionsSigner(safe7559Account, 
{
    moduleData: sessionData.moduleData,
    signer: privateKeyToAccount(sessionData.privateKey),
})

const sessionKeyAccount = await toSmartSessionsAccount(
    safe7559Account?.account, 
    sessionKeySigner
)

const paymasterClient = await createComethPaymasterClient({
    transport: http(paymasterUrl),
    chain,
});

const sessionKeyClient = createSmartAccountClient({
    account: sessionKeyAccount,
    chain,
    bundlerTransport: http(bundlerUrl),
    paymaster: paymasterClient,
    userOperation: {
        estimateFeesPerGas: async () => {
            return await paymasterClient.getUserOperationGasPrice();
        },
    },
}).extend(smartSessionActions());

const callData = encodeFunctionData({
    abi: countContractAbi,
    functionName: "count",
});

const hash = await sessionKeyClient.usePermission({
    actions: [
        {
            target: COUNTER_CONTRACT_ADDRESS,
            callData: callData,
            value: BigInt(0),
        },
    ],
});

Permissionless