> For the complete documentation index, see [llms.txt](https://onex-3.gitbook.io/onex-document/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://onex-3.gitbook.io/onex-document/blockchain-settlement.md).

# Blockchain settlement

## 6.1 Multi-Chain Architecture

ONEx supports all major blockchain ecosystems from day one:

| Chain        | Type    | Status  |
| ------------ | ------- | ------- |
| Ethereum     | EVM L1  | Launch  |
| Arbitrum     | EVM L2  | Launch  |
| Optimism     | EVM L2  | Launch  |
| Base         | EVM L2  | Launch  |
| Polygon      | EVM L2  | Launch  |
| Solana       | Non-EVM | Launch  |
| Avalanche    | EVM L1  | Launch  |
| BSC          | EVM L1  | Launch  |
| Cosmos (IBC) | Non-EVM | Phase 3 |
| zkSync Era   | EVM L2  | Phase 5 |

{% hint style="info" %}
**Note on Monad:** Previously listed, but Monad is a high-performance EVM L1 not yet at production scale as of 2025. It will be added as a future integration upon mainnet stability verification.
{% endhint %}

***

## 6.2 Intent-Based Execution (ERC-7683)

ONEx uses ERC-7683 (Cross-Chain Intents, finalized 2024) as the sole intent standard.

{% hint style="info" %}
**Note:** ERC-7521 was removed — this standard was never finalized.
{% endhint %}

Users specify *what* they want (e.g., "I want 500 USDC on Arbitrum") and a competitive solver network computes *how* to achieve it optimally. Solvers compete for execution rights, ensuring users get the best available route.

***

## 6.3 MEV Protection

| Protection Layer   | Mechanism                                                         |
| ------------------ | ----------------------------------------------------------------- |
| Flashbots Protect  | Route transactions through private mempool                        |
| Flashbots SUAVE    | Decentralized block building to minimize MEV extraction           |
| Commitment Schemes | Encrypt transaction parameters before submission                  |
| TWAP Oracles       | 30-minute minimum window prevents single-block price manipulation |

***

## 6.4 On-Chain Liquidity Engine

**TWAP Oracle (Manipulation-Resistant):** All price references use Time-Weighted Average Price with a minimum 30-minute window. Spot price usage is blocked for collateral valuation and cross-chain settlement calculations.

**Flash Loan Attack Mitigation:** Same-block liquidity change detection. Any transaction that dramatically changes pool composition in a single block triggers an automatic circuit breaker. Borrowers cannot use flash loans to manipulate the TWAP window because the TWAP span (30 minutes) cannot be manipulated within a single transaction.

**Slippage Protection:** Maximum slippage enforced by smart contract — users cannot accidentally accept unlimited slippage through UI manipulation.