# Identity and Tiers

Access to the USDREFI vault is gated by a progressive identity system. Every depositor must hold a valid Self verification. Higher deposit caps unlock via Prosperity Pass levels.

The vault itself contains zero identity logic — it simply reads a tier number from the TierRegistry.

## Architecture: API → Registry → Vault

The identity system has three layers:

1. **Off-chain API** — Checks Self verification status and Prosperity Pass level, determines tier (1, 2, or 3)
2. **On-chain TierRegistry** — Stores the result as a simple `mapping(address → uint8)`, writable by the API signer and Foundation Safe
3. **Vault** — Calls `tierRegistry.tierOf(receiver)` during deposit and applies the tier cap. No identity awareness beyond the tier number.

This design means tier logic can change — new providers, different thresholds, governance overrides — without redeploying the vault or registry. Only the API needs updating.

## Tier Definitions

| Tier                 | Eligibility                     | Per-User Cap   | Assigned By     |
| -------------------- | ------------------------------- | -------------- | --------------- |
| **0** (unregistered) | No Self verification            | Cannot deposit | —               |
| **1**                | Self verified                   | $500           | API (automatic) |
| **2**                | Self + Prosperity Pass Level 3+ | $5,000         | API (automatic) |
| **3**                | Self + Prosperity Pass Level 5+ | $15,000        | API (automatic) |

## Self Verification

[Self](https://self.xyz/) provides the baseline identity layer. Every depositor must complete Self verification, confirming they are a unique human via self-sovereign cryptographic attestation. The API checks this off-chain before assigning any tier.

## Prosperity Pass

[Prosperity Pass](https://prosperity.celo.org/) is Celo's on-chain reputation system built on Safe infrastructure by CeloPG and Kolektivo Labs. Users link wallets, claim badges for governance participation, events, and on-chain activity, earning Prosperity Points that determine their level.

The API maps Prosperity Pass levels to deposit tiers:

* **Level 3+** → Tier 2 ($5,000 cap)
* **Level 5+** → Tier 3 ($15,000 cap)

## TierRegistry Contract

A minimal on-chain contract storing per-address tier assignments:

```solidity
mapping(address => uint8) public tierOf;

function setTier(address user, uint8 tier) external onlyAuthorized;
function setTierBatch(address[] users, uint8[] tiers) external onlyAuthorized;

// Authorized: API signer + Foundation Safe (admin override)
```

The TierRegistry is intentionally generic. Future identity providers, reputation systems, or governance-based allowlisting can all feed into the same interface without changes to the vault or registry contracts.