Vault Architecture

System Overview

The Solen Defi Vault System implements a yield-bearing stablecoin vault with modular architecture for asset management, price discovery, and fee accumulation. The system uses a separation of concerns pattern with dedicated contracts for minting, redemption, and oracle management.

📋 See Contract Addresses for deployed contract addresses.

Core Components

Manager - Deploys funds, ensures redemption liquidity, and updates prices

Vault.sol - ERC20 token representing user shares. Handles minting/burning when users deposit/withdraw, with transfer hook and multi-token support

TellerMint.sol - User deposit entry point. Calculates shares based on oracle prices, applies fees, and calls vault to mint shares

TellerRedeem.sol - Redemption manager with cooldown period. Users request redemptions, then claim after cooldown expires

Oracle.sol - Price feed with 8 decimal precision. Is pausable to stop minting/redeeming and triggers fee accumulation on updates

OracleUpdater.sol - Safety wrapper validating price updates against max APR changes. Auto-pauses on suspicious movements, to allow for manual intervention

FeeAccumulator.sol - Tracks management fees (time-based) and performance fees (above highwater mark). Updates on oracle price changes

AuthorityEnumerable.sol - Permission management extending Solmate’s Authority with enumeration capability

Architecture Diagram

Key Operations

1. Deposit: User → TellerMint → Vault (mints OCUSD shares)
2. Redeem Request: User → TellerRedeem (locks OCUSD, starts cooldown)
3. Claim: User → TellerRedeem → Vault (burns OCUSD, returns USDT)
4. Price Update: Manager → OracleUpdater → Oracle → FeeAccumulator
5. Asset Deployment: Manager → Vault → External Protocols
6. Fee Collection: FeeAccumulator → Vault (USDT) → Manager
7. Emergency Pause: Manager → Oracle (halts minting/redeeming)
8. Permissions: Admin → AuthorityEnumerable → All Contracts

Design Patterns

The vault combines battle-tested patterns from BoringVault and USDX. The vault core is forked from BoringVault, while the separate minting and redeem contracts follow USDX patterns.

1. Modular Upgradability

Swaps contracts instead of using proxies:

• No proxy complexity or storage collision risks
• Immutable core (Vault) with upgradeable periphery (Tellers)
• Users always interact with the same OCUSD token address

2. USDX-Style Tellers

Separates user operations from vault logic:

• TellerMint: Deposit entry point
• TellerRedeem: Exit with cooldown mechanism
• Vault: Immutable core, only accessible via Tellers

3. Hook-Based Fees

Oracle triggers FeeAccumulator on price updates:

• Time-based management fees
• Performance fees above highwater mark
• Extensible without vault changes

4. Enumerable Authority

Solmate’s Authority with enumeration for permission auditing and fine-grained access control.

5. Safety Wrapper (OracleUpdater)

Bounds price updates to maximum APR to prevent manipulation.

6. Redemption Queue

Orderly withdrawals with cooldown:

• Users queue redemptions (OCUSD locked)
• Anyone can trigger claim after cooldown
• Predictable liquidity requirements

7. Multi-Asset Ready

While USDT-only now, supports future expansion:

• Multiple deposit assets
• Cross-asset redemptions
• Asset-specific Teller logic

Configuration Parameters

Fee Parameters

• Management Fee: Annual fee on total assets (basis points)
• Performance Fee: Fee on profits above highwater mark (basis points)

Oracle Parameters

• Max APR Update: Maximum price change per update

Deposit/Redemption Parameters

• Fee: Transaction fee (basis points)
• Min/Max Amount: Deposit/redemption limits (USDT/OCUSD)
• Cooldown: Redemption delay before claims