> For the complete documentation index, see [llms.txt](https://docs.ethosis.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.ethosis.org/protocol/idle-capital.md).

# Parked capital

A book of resting offers needs lenders willing to keep capital on standby. Capital that sits in a wallet earning nothing has a cost, and lenders will not leave much of it there for long. Ethosis takes the approach Morpho Optimizer used on top of Aave and Compound: put the unmatched capital into a pooled market, and pull it out at the exact moment a match lands.

## The mechanism

1. The lender sets `parkIdle` on their offers and grants an approval to the `IdleVaultAdapter`.
2. The adapter moves the lender's USDG into a **whitelisted Morpho Blue USDG vault** on Robinhood Chain. The vault shares are held for the lender's own account; Ethosis has an allowance over them, not custody.
3. The lender's standing offers stay live, and the relayer counts the vault balance as available capacity.
4. When one of those offers is matched, `LoanDesk` calls the adapter to pull precisely the fill amount out of the vault and pass it to the borrower within the same transaction.
5. On repayment, the proceeds flow back into the vault automatically as long as the lender still has `parkIdle` set.

The lender earns the vault's pool rate while waiting, and the peer-to-peer rate once matched.

## Which vaults qualify

Only vaults approved through the PolicyController can be used. The whitelist consists of a single, well-established USDG vault with a conservative curator. Adding another vault is a timelocked parameter change with a published rationale. See [Parameter governance](/transparency/governance.md).

## What the lender is signing up for

Parking is opt-in precisely because it introduces risks that the core protocol does not have:

* **Vault risk.** While parked, the lender is exposed to the Morpho vault's underlying markets and its curator's decisions.
* **Withdrawal liquidity.** If the vault happens to be fully utilised when a match occurs, the just-in-time withdrawal fails and the fill reverts for that slice. The relayer tracks vault liquidity and will not propose a slice it cannot fund.
* **Composability surface.** The adapter is one more contract on the origination path. It is small, works purely through allowances, and is in scope for every audit.

## Cost

The idle-capital yield share (5% of vault yield) appears on the fee page as scheduled. It takes effect once enabled through the timelock; until that happens, parking carries no fee.

## Limits on the adapter

* Capital goes only to the whitelisted vault or into an origination, never anywhere else.
* Vault shares are never rehypothecated.
* Retargeting the adapter to a different vault requires a timelocked, publicly logged change.


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