Shutdown mode

There is a special shutdown mode in Marginly v1. This mode is enabled by smart contract admin when there is system insolvency, that is:

• When there is not enough USDC collateral value to support the entire ETH debt value

• When there is not enough ETH collateral value to support the whole USDC debt value

System insolvency is a critical situation in which the protocol stops functioning correctly and thus requires the winding down of user positions and protocol instantiation. In normal market conditions and the absence of "black swans" events like the sudden USDC depeg or a protocol or AMM hack with depletion of liquidity, we wouldn't expect a shutdown to happen. This is a once-in-a-lifetime event, yet it still requires proper handling.

In the shutdown mode, no new positions are allowed to be opened, and the side opposite to the insolvent side is responsible for restoring the system's solvency at its expense. If shorts are insolvent (ETH debt value > USDC collateral value), longs will pay with their ETH collateral to reduce the system's ETH debt until the solvency is restored. If longs are insolvent (USDC debt value > ETH collateral value), shorts will pay with their USDC collateral to reduce the system's USDC debt until the solvency is restored.