> 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/architecture/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).
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`
## 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
Fluid fTokens adapter: how the underlying balances reported to the NAV Calculator are derived.
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", ""]` from the fToken's onchain 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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