> For the complete documentation index, see [llms.txt](https://docs.kpk.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.kpk.io/funds/infrastructure/onchain-accounting/meta-balance-adapters/euler-vaults.md).
# Euler Vaults
One immutable meta-adapter that reports an account's position in *any* Euler V2 ERC-4626 vault — both the EulerEarn aggregator vaults and the core eVaults (EVK, the lend/borrow product). Which vaults it queries is a governed instance set on the NAV Calculator; the adapter holds no per-vault state.
* **Type:** Meta-adapter
* **protocolSubId:** `keccak256("euler-vaults")`
* **Instance key:** the vault address, widened to `bytes32`
* **Source:** [`EulerVaultsMetaBalanceAdapter.sol`](https://github.com/karpatkey/onchain-accounting/blob/main/src/balances/MetaBalanceAdapters/EulerVaultsMetaBalanceAdapter.sol)
***
## Positions returned
Up to two legs per vault, both denominated in the vault's underlying asset:
| Leg | PositionKind | isDebt | Description |
| ------ | ---------------------------- | ------- | ---------------------------------------------------------------------------------------- |
| Supply | `Supplied` *or* `Collateral` | `false` | `convertToAssets(balanceOf)`; `Collateral` if enabled as EVC collateral, else `Supplied` |
| Borrow | `Borrowed` | `true` | `debtOf(account)` — core eVaults only |
A vault returns an empty result when its asset is unregistered, excluded by `assetFilter`, or the account has neither supply nor debt. Because an Euler vault's debt is denominated in the **same** asset as its supply, an unregistered asset already suppresses both legs together — so this adapter is structurally exempt from the [collateral-without-debt](/funds/infrastructure/onchain-accounting/balance-adapters.md#how-an-adapter-is-built) suppression the mixed-asset adapters need.
`debtOf` and the EVC lookups are read through **bounded, ABI-validated staticcalls** rather than `try/catch`, so EulerEarn aggregators (which lack them) and non-Euler ERC-4626 tokens degrade gracefully — no debt leg, supply classified as `Supplied`. The distinction matters: `try/catch` does not intercept a call to a code-less address (Solidity's `extcodesize` precheck reverts in the calling frame) nor a return-data decode failure (the decode also runs in the calling frame, after the call returned), and either would otherwise drop the whole instance — supply **and** debt legs — silently suppressing a real debt and over-reporting NAV.
A `debtOf` that **reverts** and one that **runs out of gas** are treated differently, and the difference is load-bearing. A revert is an answer: an EulerEarn aggregator has no `debtOf` at all, and reading `0` for it is correct. Starvation is not an answer, so the read **fails closed** rather than recording zero debt. In Euler's core topology that matters beyond the one vault: an account borrows from a **controller** vault while its collateral sits in others, so on the controller `balanceOf` is `0` — suppressing its debt leg leaves that instance with no legs at all, while sibling vaults still report their collateral in full. The result is unoffset collateral and an over-reported NAV that nothing inside the instance can correct; only refusing to answer can. See [a starved read is not an empty read](/funds/infrastructure/onchain-accounting/balance-adapters.md#how-an-adapter-is-built).
***
## Balance calculation
Euler Vaults adapter — how the underlying balances reported to the NAV Calculator are derived.
```
supplied = vault.convertToAssets(vault.balanceOf(account)) // isDebt = false
debt = IEulerEVault(vault).debtOf(account) // guarded read; isDebt = true, core eVaults only
```
Supply classification: `Collateral` if `vault` appears in `IEVC(vault.EVC()).getCollaterals(account)`, otherwise `Supplied`.
***
## Identity
* **positionId:** `abi.encode(address vault)` — the vault address (both legs share it)
* **positionKind:** `Supplied` · `Collateral` · `Borrowed`
There is no `labels` field on the position. The adapter implements `positionLabels(positionId)`, which returns `["Vault", ""]` from the vault's on-chain name — surfaced only by the verbose reads (`getAccountPositionsVerbose` / `getAccountNavVerbose`); the full breadcrumb is `[protocolName, ...labels]`.
***
## Constructor
```solidity
constructor(address navCalculator_)
```
| Parameter | Description |
| ---------------- | ------------------------------------------------------- |
| `navCalculator_` | NAV Calculator contract (asset registry + instance set) |
***
## Registration
Meta-adapter. Register once and seed its vaults with `addMetaBalanceAdapter(adapter, instances)`, then adjust with `addMetaInstances(adapter, instances)` / `removeMetaInstances(adapter, instances)` (MANAGER-gated). Each instance coordinate is a **vault address widened to `bytes32`** (decoded via `_toAddress`). Adding a new vault is a config call — no new deploy.
---
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