# Simulate Transactions

> Documentation index: [llms.txt](https://namera.ai/llms.txt).

Source: https://namera.ai/docs/sdk/guides/transactions/simulate-transactions

Preview calls and check session-key policies before submitting.

Use `executions.simulate()` to inspect a transaction without signing or
submitting it. Simulation does not reserve spending or gas budgets.

## Simulate a Transfer [#simulate-a-transfer]

Use an [authenticated client](https://namera.ai/docs/sdk/authentication) and a session key
installed on **Base Sepolia**. The account needs the test ETH being transferred.
Replace the example IDs and recipient with your own.

```sh
npm install @namera-ai/sdk viem
```

```ts title="index.ts"
import { NameraClient, type SimulateExecutionRequest } from "@namera-ai/sdk";
import { parseEther } from "viem";

const namera = new NameraClient({ apiKey: process.env.NAMERA_API_KEY! });

const request = {
  namespace: "eip155",
  walletId: "0199dfe1-0000-7000-8000-000000000001",
  sessionKeyId: "0199dfe1-0000-7000-8000-000000000002",
  chainId: "eip155:84532",
  calls: [
    {
      to: "0x2222222222222222222222222222222222222222",
      value: parseEther("0.001"),
      data: "0x",
    },
  ],
} satisfies SimulateExecutionRequest;

const simulation = await namera.executions.simulate(request);
if (!simulation.success) throw new Error(simulation.error.message);

console.log(simulation.data);
```

<div className="docs-response">

```json
{
  "namespace": "eip155",
  "walletId": "0199dfe1-0000-7000-8000-000000000001",
  "chainId": "eip155:84532",
  "account": "0x1111111111111111111111111111111111111111",
  "callsSucceeded": true,
  "simulation": {
    "userOperation": {
      "source": "eth_estimateUserOperationGas",
      "callGasLimit": "50000",
      "verificationGasLimit": "100000",
      "preVerificationGas": "50000",
      "maxFeePerGas": "1000000000",
      "maxPriorityFeePerGas": "1000000"
    },
    "calls": {
      "source": "viem.simulateCalls",
      "results": [{ "status": "success", "returnData": "0x", "gasUsed": "21000" }],
      "assetChanges": [],
      "transfers": [
        {
          "callIndex": 0,
          "from": "0x1111111111111111111111111111111111111111",
          "to": "0x2222222222222222222222222222222222222222",
          "value": "1000000000000000"
        }
      ]
    }
  },
  "allowed": true,
  "sessionKeyId": "0199dfe1-0000-7000-8000-000000000002"
}
```

</div>

Gas estimates are illustrative. Quantities shown as decimal strings in JSON
are `bigint` values in the SDK.

## Read the Result [#read-the-result]

- `callsSucceeded` reports whether the simulated calls succeeded.
- `allowed` reports the policy decision for the selected session key.
- `simulation.calls` contains per-call results, detected asset changes, and native transfers.
- If `allowed` is `false`, `denials` identifies the session key, policy, and denial code.

If simulation itself fails, the SDK returns `success: false`; handle it as an
[error](https://namera.ai/docs/sdk/handling-results-and-errors).

## Execute the Same Calls [#execute-the-same-calls]

After reviewing the result, submit the same request with sponsorship enabled:

```ts title="index.ts"
if (!simulation.data.callsSucceeded || !simulation.data.allowed) {
  throw new Error("Review the simulation before executing.");
}

const execution = await namera.executions.execute({ ...request, sponsor: true });
if (!execution.success) throw new Error(execution.error.message);

console.log(execution.data);
```

<div className="docs-response">

```json
{
  "namespace": "eip155",
  "submissionId": "0199dfe1-0000-7000-8000-000000000003",
  "status": "prepared",
  "userOperationHash": "0x1111111111111111111111111111111111111111111111111111111111111111"
}
```

</div>

<Callout title="A preview is not a guarantee">
  Balances, permissions, and available budgets can change after simulation. Execution checks them
  again. The second snippet submits a real testnet transaction.
</Callout>

Next, [track the submission](https://namera.ai/docs/sdk/guides/transactions/track-transactions).