> 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/fluid-ftokens.md).

# Fluid fTokens

One immutable meta-adapter that reports an account's supply position in any Fluid fToken (an ERC-4626 lending vault). Each configured fToken contributes a single `Supplied` leg denominated in the fToken's underlying asset.

* **Type:** Meta-adapter
* **protocolSubId:** `keccak256("fluid-ftokens")`
* **Instance key:** the fToken (ERC-4626 vault) address, widened to `bytes32`.
* **Source:** [`FluidFTokensMetaBalanceAdapter.sol`](https://github.com/karpatkey/onchain-accounting/blob/main/src/balances/MetaBalanceAdapters/FluidFTokensMetaBalanceAdapter.sol)

***

## Positions returned

One leg per configured fToken:

| Leg    | PositionKind | isDebt  | Description                                                |
| ------ | ------------ | ------- | ---------------------------------------------------------- |
| Supply | `Supplied`   | `false` | The fToken share balance converted to the underlying asset |

A leg is dropped when the underlying asset is not registered in NAVCalculator, when the computed amount is zero, or when filtered out by `assetFilter`.

***

## Balance calculation

<figure><img src="/files/vmaei6XMbqOqP5wBzZH7" alt="Flowchart of the Fluid fTokens balance adapter: read calls derive position legs into PositionBalance entries."><figcaption><p>Fluid fTokens adapter — how the underlying balances reported to the NAV Calculator are derived.</p></figcaption></figure>

For the fToken at the instance coordinate:

```
asset  = fToken.asset()
amount = fToken.convertToAssets(fToken.balanceOf(account))
```

The amount is reported in the underlying asset (`asset`).

***

## Identity

* **positionId:** `abi.encode(address fToken)`
* **positionKind:** `Supplied`

There is no `labels` field on the position. The adapter implements `positionLabels(positionId)`, which returns `["Lending", "<fToken symbol()>"]` from the fToken's on-chain symbol — surfaced only by the verbose reads (`getAccountPositionsVerbose` / `getAccountNavVerbose`); the full breadcrumb is `[protocolName, ...labels]`.

***

## Constructor

```solidity
constructor(address navCalculator_)
```

| Parameter        | Description                                                                       |
| ---------------- | --------------------------------------------------------------------------------- |
| `navCalculator_` | NAVCalculator address, used for the registered-asset registry. Must be a contract |

***

## Registration

Register the adapter with `addMetaBalanceAdapter(adapter, instances)`, then add or remove fTokens with `addMetaInstances(adapter, instances)` / `removeMetaInstances(adapter, instances)`. The instance coordinate is the fToken (ERC-4626 vault) address widened to `bytes32`.


---

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