# Execution Chain Finality

Excluding probabilistic finality, there are two types of execution chains in terms of finality: 

1. The first type includes chains with single-phase finality, such as solo PoS chains or Restaking-based PoS chains, which achieve finality through their consensus mechanisms. 
2. The second type, L2 blockchains, has a two-phase finality. \
   a.  The first phase uses their consensus, usually, Proof of Authority (PoA), to reach soft finality. \
   b.  The second phase involves a high-security L1 chain by validity proofs or fraud proofs to obtain          \
   L1's [settlement assurance](https://medium.com/@nic__carter/its-the-settlement-assurances-stupid-5dcd1c3f4e41).

Omnity Route Canisters acquire transaction batches and proofs from the DA layer in rollup cases. This is achieved through Ethereum's native integration or HTTPS outcalls for alternative DAs, such as [Celestia](https://celestia.org/), [EigenDA](https://www.eigenlayer.xyz/), or [Validium](https://ethereum.org/en/developers/docs/scaling/validium). 

The verification process differs based on the rollup type: ZKP verification is used for ZK-rollups. For OP-rollups, soft finality is ensured by cross-checking events on the L2 and commitments on the DA. Omnity bypasses the challenge period because the soft finality is good enough for its security model, reducing the cross-chain latency between OP-rollups and other chains from 7 days to around a few minutes.

When an execution chain suffers 51% attacks, the Route will be paused upon a fraud-proof or governance decision from Omnity DAO. After that, it is up to the Omnity DAO to decide whether to resume the connection by selecting the canonical chain or permanently removing the blockchain. 

In the latter case, blockchain heritages will be established on IC based on a snapshot of token balances at a certain height determined by the DAO. Token holders can redeem heritage to the settlement chain by signing a message with their execution chain wallets and submitting it to an executor smart contract on IC.


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