The Vault Manager is the core credit engine of Forged. It allows zkLTC collateral to support fUSD debt while enforcing collateralization constraints.
A vault is a collateralized debt position. It contains two primary balances:
- Collateral: native zkLTC locked in the vault.
- Debt: fUSD minted against that collateral.
The vault system is overcollateralized by design. fUSD is not created as unsecured credit. It is minted only when collateral value, oracle price, and protocol limits allow the resulting position to remain above the required collateral ratio.
4.1 Collateralized debt position logic
The central equation is the collateral ratio:
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Collateral Ratio = Collateral Value / fUSD Debt
Collateral value is calculated from the vault’s zkLTC balance and the current oracle price. Debt is the outstanding fUSD minted by the vault.
For example, assume zkLTC is valued such that a vault’s collateral is worth 1,000 fUSD. With a 200% minimum collateral ratio, the maximum debt allowed by the ratio is 500 fUSD:
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1,000 collateral value / 500 debt = 200%
If the vault mints 400 fUSD, its collateral ratio is 250%:
The difference between 250% and the 200% minimum is the operating buffer. The larger the buffer, the more room the position has before it becomes constrained or eventually liquidatable.
4.2 Why overcollateralization matters
Overcollateralized debt serves three purposes.
First, it protects fUSD issuance. Since fUSD is created against collateral, the system requires collateral value to exceed debt value. This gives the protocol room to absorb price movement before debt becomes unsafe.
Second, it creates transparent solvency rules. A vault does not depend on subjective creditworthiness. Its health is measured by collateral value, debt, and protocol thresholds.
Third, it enables permissionless liquidation. When a position falls below the liquidation threshold, the system does not need to negotiate with the borrower. The position becomes actionable under predefined rules.
The cost of this structure is capital inefficiency. A 200% ratio means the borrower must lock significantly more collateral value than the fUSD they mint. Forged chooses this tradeoff to keep the credit system conservative and legible.
4.3 Vault lifecycle
A vault can move through several states.
Deposit collateral: zkLTC is locked into the vault. This increases collateral but does not create debt by itself.
Mint fUSD: the vault increases debt and receives newly minted fUSD. The transaction is valid only if the resulting debt respects the debt ceiling, minimum debt, and minimum collateral ratio.
Repay debt: fUSD is returned and burned, reducing debt. Repayment improves collateralization because the same collateral backs less debt.
Withdraw collateral: zkLTC is removed from the vault. Withdrawal reduces backing and is permitted only if the remaining vault stays above the minimum collateral ratio.
Close vault: the full debt is repaid, fUSD is burned, and remaining collateral is returned.
Liquidation: if the vault falls below the liquidation threshold, debt can be repaid or offset and collateral can be seized according to liquidation rules.
4.4 The 200% minimum collateral ratio
The 200% minimum collateral ratio is the standard requirement for minting and normal vault adjustments. It applies when opening a debt position, minting additional fUSD, or withdrawing collateral.
This means the vault must satisfy:
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Collateral Value × 10,000 >= Debt × 20,000
Equivalently:
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Collateral Value >= 2 × Debt
The ratio is enforced after the proposed action. A vault with 300% collateralization can mint or withdraw until it approaches the 200% boundary. A vault already near 200% has very little room for additional borrowing or collateral withdrawal.
The 200% threshold is therefore the capital-efficiency boundary. It is not the liquidation point. It is the minimum safe operating requirement for voluntary vault actions.
4.5 The 150% liquidation ratio
The liquidation ratio is 150%. A vault becomes liquidatable when its collateral ratio falls below this threshold.
This means a vault can exist between 200% and 150%, but it becomes constrained. It may not be able to mint more fUSD or withdraw collateral, but it is not yet liquidatable. The zone between 200% and 150% acts as a stress buffer.
The thresholds create three practical states:
| Collateral Ratio | State | Interpretation |
|---|
| Above 200% | Healthy operating range | Minting and withdrawal may be possible subject to limits. |
| 150% to 200% | Under operating requirement but not liquidatable | Position should be repaired through repayment or added collateral. |
| Below 150% | Liquidatable | Debt can be resolved through liquidation mechanisms. |
For example, consider a vault with 1,000 fUSD worth of collateral and 500 fUSD of debt. The ratio is 200%. If collateral value falls to 800 fUSD, the ratio becomes 160%. The vault is below the normal 200% operating requirement but still above the 150% liquidation threshold. If collateral value falls to 740 fUSD, the ratio becomes 148%, and the vault is liquidatable.
4.6 Liquidation price
The liquidation price is the oracle price at which a vault’s collateral ratio reaches the liquidation threshold. It depends on collateral amount, debt, and the liquidation ratio.
Conceptually:
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Liquidation Price = Debt × Liquidation Ratio / Collateral Amount
With 10 zkLTC collateral and 500 fUSD debt, the 150% liquidation value is 750 fUSD. The liquidation price is therefore 75 fUSD per zkLTC:
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500 × 150% = 750 required collateral value
750 / 10 zkLTC = 75 fUSD per zkLTC
If zkLTC trades above 75, the vault remains above liquidation. If the oracle price falls below 75, the vault becomes liquidatable.
4.7 Liquidation mechanics
Liquidation resolves unsafe debt by repaying or offsetting fUSD debt and seizing collateral at a penalty. The current liquidation penalty is 10%.
A liquidator can repay up to the vault’s outstanding debt, subject to available collateral. For every 1 fUSD of debt repaid, collateral worth 1.10 fUSD can be seized at the oracle price. This extra 10% is the liquidation incentive and penalty.
Example:
- Vault debt: 500 fUSD.
- Liquidator repays: 100 fUSD.
- Liquidation penalty: 10%.
- Collateral seized: 110 fUSD worth of zkLTC.
After this liquidation slice:
- Vault debt decreases by 100 fUSD.
- Vault collateral decreases by 110 fUSD worth of zkLTC.
- The repaid fUSD is burned.
- The liquidator receives the seized collateral.
Liquidation can be partial. If the liquidator repays less than total debt, the vault remains open with reduced debt and reduced collateral. If enough debt is repaid, the remaining position may move back above the liquidation threshold. If the position remains unsafe, further liquidation can occur.
4.8 Stability Pool liquidation path
The Stability Pool provides a second liquidation path. Instead of an external liquidator supplying fUSD, the vault system can use pooled fUSD from the Stability Pool to offset unsafe debt. The offset fUSD is burned, and seized zkLTC collateral is sent to the pool.
The economic effect is similar to external liquidation:
- Unsafe vault debt is reduced.
- fUSD used for repayment is burned.
- Collateral is removed from the vault.
- The collateral is distributed to Stability Pool participants through pool share accounting.
The difference is that the fUSD source is pooled liquidity rather than a single liquidator. The Stability Pool therefore acts as standing liquidation capacity for the system.
4.9 System limits
The vault system includes additional constraints:
- Debt ceiling: limits total fUSD debt that can be minted through vaults. The current configured ceiling is 1,000,000 fUSD.
- Minimum debt: prevents dust vaults. The current minimum debt is 10 fUSD.
- Minimum collateral ratio: currently 200%, used for minting and withdrawal safety.
- Liquidation ratio: currently 150%, used to determine liquidation eligibility.
- Liquidation penalty: currently 10%, used to calculate collateral seized during liquidation.
- Oracle valuation: collateral value is determined through the oracle price.
These limits define the vault system’s issuance envelope. The debt ceiling controls aggregate expansion. The minimum debt controls position granularity. The collateral ratios define individual vault safety. The penalty creates liquidation incentive.