> 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/price-feeds/ostoken.md).

# osToken (osETH / osGNO)

Custom price feed for **StakeWise V3 osTokens**. No direct osToken/USD feed exists, so the price is composed from the StakeWise vault controller's osToken→underlying conversion rate and the NAV's own underlying/USD base price. A single generic adapter prices **osETH** on Ethereum (underlying ETH) and **osGNO** on Gnosis (underlying GNO) via separate instances. On mainnet, **osETH** also carries an independent [cross-rate](/funds/infrastructure/onchain-accounting/price-feeds/cross-rate.md) **monitor** feed (`ETH/USD × osETH/ETH`, with a Redstone `osETH/ETH` leg) registered as a [divergence monitor](/funds/infrastructure/onchain-accounting/price-feeds.md#primary-feed-and-divergence-monitors) — a market depeg flags osETH `irregular` without moving its price.

**Source:** [`osToken_CustomPriceFeed.sol`](https://github.com/karpatkey/onchain-accounting/blob/main/src/prices/protocols/osToken_CustomPriceFeed.sol)

***

## Approach

`OsTokenVaultController.convertToAssets(1e18)` × NAV base underlying/USD (`getPriceDataNoDivergence(WETH)` on mainnet, `getPriceDataNoDivergence(GNO)` on Gnosis)

{% hint style="info" %}
The base/USD term is sourced from the NAV's own selector — see [Base/USD from the NAV's own selector](/funds/infrastructure/onchain-accounting/price-feeds.md#base-usd-from-the-navs-own-selector).
{% endhint %}

<figure><img src="/files/yyKN3FkFy0VOLOFgURnG" alt="Left-to-right flowchart of the osToken (osETH / osGNO) price feed: rate and Chainlink inputs combine into a USD price, with a staleness gate."><figcaption><p>osToken (osETH / osGNO) price feed — how its oracle inputs compose into a USD price, with the staleness gate.</p></figcaption></figure>

***

## Price calculation

```
price = convertToAssets(1e18) × (underlying/USD) / 1e18
```

| Input                   | Source                                                                                        | Description                                                                   |
| ----------------------- | --------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------- |
| `convertToAssets(1e18)` | `IOsTokenVaultController.convertToAssets`                                                     | Underlying backing per 1 osToken (18 dec)                                     |
| `underlying/USD`        | NAV base — `getPriceDataNoDivergence(WETH)` on mainnet, `getPriceData(GNO)` on Gnosis (8 dec) | the NAV's primary underlying/USD price — ETH/USD for osETH, GNO/USD for osGNO |

`convertToAssets` returns the underlying-per-osToken exchange rate, which rises as StakeWise staking rewards accrue. The underlying's USD price is read from the NAV's own primary feed — ETH/USD via `getPriceDataNoDivergence(WETH)` on mainnet, GNO/USD via `getPriceDataNoDivergence(GNO)` on Gnosis. The divisor is the fixed `1e18`. Output is **8 decimals** (inherited from the NAV's base price).

***

## Constructor

```solidity
constructor(
    address osToken_,
    address osTokenVaultController_,
    address nav_,
    address baseAsset_
)
```

| Parameter                 | Description                                                                                |
| ------------------------- | ------------------------------------------------------------------------------------------ |
| `osToken_`                | osToken address (osETH or osGNO; the supported underlying asset)                           |
| `osTokenVaultController_` | StakeWise `OsTokenVaultController` for this osToken (must be a contract)                   |
| `nav_`                    | NAVCalculator (proxy) — supplies the base asset's USD price via `getPriceDataNoDivergence` |
| `baseAsset_`              | The registered base asset whose USD price is read (WETH on mainnet, GNO on Gnosis)         |

***

## Staleness

The underlying/USD leg has no independent heartbeat here — its freshness comes from the NAV: the result is marked stale if the NAV reports the base asset (WETH on mainnet, GNO on Gnosis) stale — all its feeds stale. The base leg's `updatedAt` comes from the NAV's selected feed. The result is also marked stale if the underlying/USD answer is `≤ 0` or if `convertToAssets(1e18)` returns `0`. The `convertToAssets` call has no independent age check — it is a live view on the StakeWise controller.

***

## Chains

Deployed on **Ethereum** (osETH, underlying ETH/USD) and **Gnosis** (osGNO, underlying GNO/USD), one instance per osToken.


---

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