Smart Sessions And Policies

dotnet add package Nethereum.Web3
dotnet add package Nethereum.AccountAbstraction

using System.Numerics;
using Nethereum.Hex.HexConvertors.Extensions;
using Nethereum.AccountAbstraction.ERC7579.Modules.SmartSession;
using Nethereum.AccountAbstraction.Contracts.Modules.SmartSessions.SmartSession;
using Nethereum.AccountAbstraction.Contracts.Modules.SmartSessions.SmartSession.ContractDefinition;
using Nethereum.AccountAbstraction.Contracts.Modules.SmartSessions.Policies.SudoPolicy;
using Nethereum.AccountAbstraction.Contracts.Modules.SmartSessions.Policies.SudoPolicy.ContractDefinition;
using Nethereum.AccountAbstraction.Contracts.Modules.SmartSessions.Policies.UniActionPolicy;

using Nethereum.AccountAbstraction; // AATransactionReceipt
using Nethereum.AccountAbstraction.Client;
using Nethereum.AccountAbstraction.Contracts.Core.NethereumAccount;
using Nethereum.AccountAbstraction.ERC7579.Modules;
using Nethereum.AccountAbstraction.ERC7579.Modules.SmartSession;
using Nethereum.Signer;

// 1. A fresh keypair - the agent/bot process holds ONLY this, never the account owner's key.
var sessionKey = EthECKey.GenerateKey();

// 2. Scope it to exactly one action: call count() on `counterAddress`, no other function, no other
//    target. SudoPolicy means "no further restriction on the args of THIS action" - see below for
//    when you'd use UniActionPolicy or a spending limit instead.
var salt = new byte[32];
Guid.NewGuid().ToByteArray().CopyTo(salt, 0);

var config = new SmartSessionConfig()
    .WithSessionValidator(sessionValidatorAddress)              // a deployed ECDSASessionValidator
    .WithSessionValidatorInitData(sessionKey.GetPublicAddress())
    .WithSalt(salt)
    // UnrestrictedAction's selector arg is the 4-byte function selector as a hex string, e.g. "0x06661abd".
    .WithAction(ActionDataBuilder.UnrestrictedAction(counterAddress, countSelector, sudoPolicyAddress));

// 3. Enable it: installs SmartSession (first time only) and this session, in one UserOp, signed by
//    the account's OWNER key - the session key never touches this step.
config.ModuleAddress = smartSessionAddress;
var accountService = new NethereumAccountService(web3, account.Address);
accountService.UseAccountAbstraction(account, aaClient);
await accountService.InstallModuleAndWaitForReceiptAsync(config);

// 4. Attach a SEPARATE NethereumSmartAccount for the SAME address, authenticated by the session key.
var permissionId = await smartSession.GetPermissionIdQueryAsync(config.ToSession());
var sessionAccount = aaClient.GetAccount(
    account.Address,
    new SmartSessionKeySigningService(sessionKey, permissionId),
    new SmartSessionValidatorModule(smartSessionAddress, permissionId));

// 5. From here, the session key signs - the owner key is never involved again.
counter.UseAccountAbstraction(sessionAccount, aaClient);
var receipt = (AATransactionReceipt)await counter.CountRequestAndWaitForReceiptAsync();

var result = await sudoPolicyService.CheckActionQueryAsync(
    configId, account, target, value, calldata);
// result == 0 (SIG_VALIDATION_SUCCESS) - SudoPolicy never inspects arguments.

using Nethereum.AccountAbstraction.ERC7579.Modules.SmartSession;

// A DCA bot may call swap() on ONE router, up to 100 (token-unit) worth of value per call.
var maxSwapValue = BigInteger.Parse("100000000");

var policyData = new UniActionPolicyBuilder()
    .WithValueLimit(maxSwapValue)
    .Build();

var session = new SmartSessionConfig()
    .WithSessionValidator(sessionKeyValidator)
    .WithSalt(salt)
    .WithAction(new ActionDataBuilder()
        .WithTarget(uniswapRouter)
        .WithSelector(swapSelector)
        .WithUniActionPolicy(uniActionPolicy, policyData)
        .Build())
    .ToSession();

var policyInitData = new UniActionPolicyBuilder()
    .WithEqualityCheck(offset: 0, expectedValue: ownerAddress.HexToByteArray())  // arg 0 must equal owner
    .WithMaxValue(offset: 32, maxValue: capBytes)                                // arg 1 <= cap
    .WithLimitedUsage(offset: 32, refValue: capBytes, limit: totalBudget)        // AND track cumulative usage
    .Build();