GITBOOK-217: Kai's Mar 18 changes

SUMMARY.md

@@ -40,6 +40,7 @@
   * [Swagger Playground](https://cronos.org/swagger?network=mainnet)
 * [⚙️ Dev Tools & Integrations](for-dapp-developers/dev-tools-and-integrations/README.md)
   * [Overview of dev tools & integrations](for-dapp-developers/useful-projects-on-cronos/overview-of-dev-tools-and-integrations.md)
+  * [Account Abstraction (Experimental)](for-dapp-developers/dev-tools-and-integrations/account-abstraction-experimental.md)
   * [Tenderly](for-dapp-developers/dev-tools-and-integrations/tenderly.md)
   * [Band Protocol](for-dapp-developers/useful-projects-on-cronos/band-protocol.md)
   * [Covalent](for-dapp-developers/useful-projects-on-cronos/covalent.md)

for-dapp-developers/dev-tools-and-integrations/account-abstraction-experimental.md

@@ -0,0 +1,155 @@
+# Account Abstraction (Experimental)
+
+## Introduction
+
+Account Abstraction simplifies blockchain interactions by allowing smart contracts to serve as user accounts, merging contract capabilities with account management. The Titan upgrade opens the door for Account Abstraction to become reality on Cronos Testnet.\
+\
+Account Abstraction opens up possibilities for numerous use cases such as multi-signature transactions, social recovery, contract whitelisting, custom gas tokens, subsidizing gas fees, and much more. It expands the use-case potential of DApps and enables a more intuitive user experience. \
+
+
+Key components have been developed to facilitate the development of Account Abstraction. Note that some of these components are still at an experimental stage:  
+
+* **User Operations**, serve as a new type of transaction object containing additional data, allows for custom transaction and security configurations.
+* **JSON-RPC API debug\_traceCall,** allows for the simulation of User Operations before their actual execution on the chain. 
+* **Bundlers** serve as crucial nodes that bundle unsigned User Operations into a single package for signing and subsequent publication on the mainnet. Bundlers estimate transaction fees. 
+* **Entry Point Contract**, an audited and trusted singleton contract, is functional and can process the execution and validating User Operations. 
+
+\
+Native account abstraction is still at an experimental stage on Cronos, not yet suitable for production use case. However, there are application-level account abstraction solutions available for developers who need AA functionality now, such as [Cometh](https://docs.cometh.io/connect/quickstart/supported-networks). Please contact [Cronos Labs](https://cronoslabs.org) if you would like to be introduced to the relevant developer tool platforms. 
+
+
+
+## Send a UserOperation using userop.js
+
+In this guide, we will go through how to send a userop transaction with subsidized gas fee. \
+Here we are using [userop.js](https://github.com/stackup-wallet/userop.js) to send UserOperations but you can use any library you like, even using `curl`
+
+We will create a new project for sending transactions
+
+```bash
+mkdir userop-test
+cd userop-test
+yarn init -y
+yarn add userop
+yarn add dotenv
+```
+
+In the root directory, create a new file `.env`
+
+```
+ENTRY_POINTS=0x5FF137D4b0FDCD49DcA30c7CF57E578a026d2789
+ACCOUNT_FACTORY=0x9406Cc6185a346906296840746125a0E44976454
+NODE_RPC_URL=http://localhost:8545
+BUNDLER_RPC_URL=http://localhost:3000
+SIGNER_PKEY=0x0000000000000000000000000000000000000000000000000000000000000003
+```
+
+Create a new `index.mjs`
+
+```javascript
+import { ethers,Wallet,Contract } from "ethers";
+import { Presets,Client } from "userop";
+
+import { config } from "dotenv";
+config();
+
+const NODE_RPC_URL = process.env.NODE_RPC_URL;
+const BUNDLER_RPC_URL = process.env.BUNDLER_RPC_URL;
+const SIGNER_PKEY = process.env.SIGNER_PKEY;
+const ENTRY_POINTS = process.env.ENTRY_POINTS;
+const ACCOUNT_FACTORY = process.env.ACCOUNT_FACTORY;
+
+async function main() {
+
+  // signer is the owner of the smart account
+  const signer = new ethers.Wallet(SIGNER_PKEY)
+
+  // Initialize userop builder
+  var builder = await Presets.Builder.SimpleAccount.init(
+    signer,
+    NODE_RPC_URL,
+    {
+      overrideBundlerRpc: BUNDLER_RPC_URL,
+      entryPoint: ENTRY_POINTS,
+      factory: ACCOUNT_FACTORY,
+    }
+  );
+
+  // these two addresses are different
+  // need to fund the smart account before running this script
+  console.log(`Signer  address: ${signer.address}`);
+  console.log(`Account address: ${builder.getSender()}`);
+
+  // build a tranfer transaction
+  builder = builder
+    .execute(
+      "0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266",
+      "100",
+      ethers.utils.hexlify("0x")
+    )
+
+  // create the client
+  const client = await Client.init(
+    NODE_RPC_URL,
+    {
+      overrideBundlerRpc: BUNDLER_RPC_URL,
+      entryPoint: ENTRY_POINTS,
+      factory: ACCOUNT_FACTORY,
+    }
+  );
+
+  // send the useroperation to the bundler node
+  const res = await client.sendUserOperation(builder, {
+    onBuild: (op) => {
+      console.log("Signed UserOperation:",op);
+    },
+  });
+
+  console.log(`UserOpHash: ${res.userOpHash}`);
+
+  // !!! this step can get stuck in a local geth dev setup
+  // because the bundler node is waiting for new block event to bundle the userops
+  // try to send a new tx in the local geth dev setup to trigger bundle
+  console.log("Waiting for transaction...");
+  const ev = await res.wait();
+
+  console.log(`Transaction hash: ${ev?.transactionHash ?? null}`);
+}
+
+main().then();
+```
+
+Now send the userop by running:
+
+```bash
+$ node index.mjs
+
+Signer  address: 0x6813Eb9362372EE...19671cBA69
+Account address: 0xF249baC852124B9...1b6907FcAD
+verification gas limit: 70000
+verification gas limit: 1000000
+Signed UserOperation: {
+  sender: '0x6813Eb9362372EE...19671cBA69',
+  nonce: '0xb',
+  initCode: '0x',
+  callData: '0xb61d27f6000000000000000000000000f39fd6e51aad88f6f...27279cfffb92266000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000000000000000000000000000000000000000600000000000000000000000000000000000000000000000000000000000000000',
+  callGasLimit: '0x4443',
+  verificationGasLimit: '0xaba7',
+  preVerificationGas: '0xbfb1',
+  maxFeePerGas: '0x925761c3500',
+  maxPriorityFeePerGas: '0xd27a99500',
+  paymasterAndData: '0x',
+  signature: '0xd42139cf71d00cd7ff...5461bbd949df9500413948fd06a284029e4a777247d6dd609e72b538d60d51b'
+}
+UserOpHash: 0xdc07e08d601ff82dd509c...34c7262ccf22463f10fb2191
+Waiting for transaction...
+Transaction hash: 0xcd54434b8c949...2580930cf14045cc3829ef09feb73ec9a
+
+
+```
+
+If successful, you will see the above logs including transaction hash and userOpHash printed out.
+
+We can now verify with this tx hash on the block explorer, that we have successfully sent out a TX, and the gas fees were funded by the account address 0x6813Eb9362372EE...19671cBA69.
+
+<figure><img src="../../.gitbook/assets/Screenshot 2024-03-18 at 12.19.52 PM.png" alt=""><figcaption></figcaption></figure>