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Euler Vault Kit EVaults can route governor actions through a Newton Shield before the EVault receives the call. VaultKit’s EVault overlay encodes the governor calldata, asks Newton operators to evaluate the configured policy, and forwards the call only when the policy returns an approval attestation. This guide covers shield.eulerVault.*, which wraps EVault governor functions. For Euler Earn aggregation-vault curator and allocator actions such as reallocate, use the Euler Earn Guide.

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Install Packages

pnpm add @newton-xyz/vaultkit @newton-xyz/policy-pack-shared viem zod
pnpm add @newton-xyz/policy-pack-vaultsfyi
Add any other policy-pack modules your Shield enforces, such as RedStone or Chainalysis: 
pnpm add @newton-xyz/policy-pack-redstone @newton-xyz/policy-pack-chainalysis

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Attach the EVault Overlay

Create or attach to a Shield, then extend the client with eulerVaultActions: 
import { createShield } from '@newton-xyz/vaultkit'
import { eulerVaultActions } from '@newton-xyz/vaultkit/vendors/euler-vault'
import { defineComposite } from '@newton-xyz/policy-pack-shared'
import { vaultsfyi } from '@newton-xyz/policy-pack-vaultsfyi'

const pack = await defineComposite({
  modules: [vaultsfyi],
  chainId: '8453',
  env: 'prod',
  publicClient,
  policyAddress: '0xCompositePolicyAddress',
})

const shield = (await createShield({
  apiKey: process.env.NEWTON_API_KEY!,
  walletClient,
  rpc: process.env.RPC_URL!,
  env: 'prod',
  pack,
  vault: '0xEVault',
})).extend(eulerVaultActions)
shield.eulerVault.* produces calldata from EVault’s governor ABI and routes the call through shield.sendCall(...). The composite policy pack still owns wasmArgs; pass per-call policy inputs through prepareQueryOptions.

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Grant the Shield EVault Governance

EVault governor actions are manager actions. Borrowers and suppliers continue through normal EVault flows and do not route through the Shield. Every wrapped action is callable by the EVault governor, also called governorAdmin. To use the Shield as the policy gate, the current governor should set the EVault governor to the Shield clone or route the relevant governance authority through the clone: 
await walletClient.writeContract({
  address: '0xEVault',
  abi: eVaultAbi,
  functionName: 'setGovernorAdmin',
  args: [shield.policyClientAddress],
})
After the Shield clone is the governor, shield.eulerVault.setGovernorAdmin(...) can rotate governance again through the same policy-gated path. Unlike Euler Earn, EVault governor setters are not a two-step onchain timelock flow. A policy approval plus the EVault governor check is the control surface. setLTV includes a rampDuration argument for lowered liquidation LTVs, but that is a parameter ramp, not a governance timelock.

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Configure LTV

await shield.eulerVault.setLTV(
  '0xEVault',
  {
    collateral: '0xCollateralEVault',
    borrowLtv: 8000,
    liquidationLtv: 8500,
    rampDuration: 0,
  },
  {
    prepareQueryOptions: {
      vaultsfyi: { previousAllocationHash: '0x...' },
    },
  },
)
borrowLtv and liquidationLtv use 1e4 scale, so 8000 means 80%. liquidationLtv must be greater than or equal to borrowLtv.

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Configure Caps

Pass caps as asset-denominated amounts in the vault asset’s smallest unit, or "unlimited". VaultKit encodes them to EVault’s packed AmountCap format before building calldata. 
await shield.eulerVault.setCaps('0xEVault', {
  supplyCap: 10_000_000_000n,
  borrowCap: 5_000_000_000n,
})

await shield.eulerVault.setCaps('0xEVault', {
  supplyCap: 'unlimited',
  borrowCap: 2_500_000_000n,
})
Do not pre-encode the packed uint16 cap yourself when using shield.eulerVault.setCaps(...); the helper expects human asset amounts and rounds up to the nearest representable EVault cap.

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Wrapped Actions

CategoryHelpers
Governor administrationsetGovernorAdmin
Risk parameterssetLTV, setMaxLiquidationDiscount, setLiquidationCoolOffTime, setInterestRateModel, setCaps
Vault configurationsetHookConfig, setConfigFlags
FeessetInterestFee, setFeeReceiver
VaultKit intentionally does not wrap end-user deposit, mint, withdraw, redeem, borrow, or repay actions.

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Other Examples

await shield.eulerVault.setInterestRateModel('0xEVault', '0xInterestRateModel')

await shield.eulerVault.setMaxLiquidationDiscount('0xEVault', 1200)

await shield.eulerVault.setHookConfig('0xEVault', {
  hookTarget: '0xHookContract',
  hookedOps: 0b101,
})

await shield.eulerVault.setInterestFee('0xEVault', 1000)
await shield.eulerVault.setFeeReceiver('0xEVault', '0xFeeReceiver')
Scale fields follow the EVault ABI. LTVs, liquidation discounts, and interest fees use 1e4 scale.

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Troubleshooting

SymptomLikely causeFix
EVault governor revertThe Shield clone is not the EVault governor for that action.Grant or route governorAdmin to the Shield clone before executing.
Wrong caps onchainRaw packed caps were passed instead of asset-denominated amounts.Pass asset amounts or "unlimited" to setCaps; VaultKit handles packing.
PolicyDeniedErrorNewton evaluated the configured policy and denied the intent.Inspect the policy result, params, and per-call prepareQueryOptions.
Unexpected calldataThe wrong overlay or vault address was used.Use shield.eulerVault.* only for EVaults; use shield.euler.* for Euler Earn vaults.

Euler Earn Guide

Gate Euler Earn curator and allocator actions with shield.euler.*.

Reference

Review the generic sendCall API and expected error types.