Le Nexus Members debated for 48h without any pause/drink/sleeps to draw their final conclusion: easy AYE.
We appreciate the effort put on testing and auditing as this is very critical.

This proposal aims to upgrade the Snowbridge [Gateway](https://etherscan.io/address/0x27ca963c279c93801941e1eb8799c23f407d68e7) contract on Ethereum, which is remotely governed by OpenGov utilizing Snowbridge itself as a cross-chain governance bridge.



The related bridge hub changes are included in the 1.71 upgrade. [https://polkadot.subsquare.io/referenda/1756](https://polkadot.subsquare.io/referenda/1756)

# New Features

The upgraded gateway supports new user-facing features:

* Tighter XCM integration allowing users to send a user contructed XCM message from Ethereum to Polkadot.
* Arbitrary message passing between Ethereum and Polkadot via XCM Transact.
* Un-ordered message delivery.
* Lower fees: all fee related calculation is moved offchain and is now dynamically calculated based on live gas prices.

# Technical Details

This proposal will update the Gateway proxy at [0x27ca963c279c93801941e1eb8799c23f407d68e7](https://etherscan.io/address/0x27ca963c279c93801941e1eb8799c23f407d68e7) with a new implementation contract at [0x8a887783e945233d51881e06835ec78a8b575ece](https://etherscan.io/address/0x8a887783e945233d51881e06835ec78a8b575ece#code)

This contract was built and deployed using:

* Repository: [https://github.com/Snowfork/snowbridge](https://github.com/Snowfork/snowbridge)
* Commit: [8662d76740960aee660487221712f1537274ddb5](https://github.com/Snowfork/snowbridge/commit/8662d76740960aee660487221712f1537274ddb5)
* Command: `cd contracts; scripts/deploy.sh contracts/scripts/upgrade/DeployGateway202509.sol`

The proposal will also update a storage key that sets the default base price for the bridge at `0.1 DOT`.

Storage Key: `0xd0ed50b03e9a49e836dd934b425ba4c3`

[Key Source](https://github.com/polkadot-fellows/runtimes/blob/v1.7.1/system-parachains/asset-hubs/asset-hub-polkadot/src/xcm_config.rs#L734 "Key Source")

Verification Script: [https://gist.github.com/alistair-singh/7d4e5986fa6fcb73df71079771a2aa54](https://gist.github.com/alistair-singh/7d4e5986fa6fcb73df71079771a2aa54)

The key, value and the preimage for this ref was built with the Snowbridge `control` [tool](https://github.com/Snowfork/snowbridge/blob/8d58169683d004f4074186686e20007c6a724e99/control/preimage/src/commands.rs#L269-L270).&#x20;

# Testing

The upgrade proposal was extensively tested using simulations on forked instances of both Polkadot and Ethereum mainnet. This was done using Chopsticks and Foundry for Polkadot and Ethereum respectively.

Since the Ethereum side of snowbridge has no fallback governance or centralized escape hatches, it is critical to ensure that the upgrade does not affect the ongoing viability the gateway. In this regard, the fork tests in [ForkUpgrade202509.t.sol](https://github.com/Snowfork/snowbridge/blob/8662d76740960aee660487221712f1537274ddb5/contracts/test/ForkUpgrade202509.t.sol) verify that cross-chain signalling is preserved.

# Audits

The Ethereum contracts were audited at revision `9bcac977155belbe0fc55e2d16ac3244667a50f4`, which includes the features described above.
[Oak Security Audit Report](https://github.com/oak-security/audit-reports/blob/main/Snowbridge/2025-05-29%20Audit%20Report%20-%20Snowbridge%20v2%20v1.0.pdf "Oak Security Audit Report")

Snowbridge is a bridge that connects Ethereum and Polkadot blockchains.

- This upgrade will make the bridge better and cheaper to use.
- It will let users send more types of messages between the two blockchains.
- Messages can arrive in any order.
- Fees will be lower and based on current network costs.
- The upgrade has been carefully tested to make sure it works safely.
- A security company checked the code to find any problems.
- The changes are part of a bigger update called version 1.71.

call

Deciding

Submitted

DecisionStarted

DecisionDepositPlaced

whitelisted_caller

Upgrade Snowbridge Gateway Contract

root

wish_for_change

staking_admin

treasurer

lease_admin

fellowship_admin

general_admin

auction_admin

referendum_canceller

referendum_killer

small_tipper

big_tipper

small_spender

medium_spender

big_spender

Origin able to dispatch a whitelisted call.

Origin for signaling that the network wishes for some change

Origin able to cancel slashes and manage minimum commission.

Origin for spending up to 10,000,000 DOT from the treasury as well as generally administering it.

Origin for managing the composition of the fellowship.

Origin able to spend around 250 DOT from the treasury at once.

Origin able to spend around 1,000 DOT from the treasury at once.

Origin able to spend around 10,000 DOT from the treasury at once.

Origin able to spend around 100,000 DOT from the treasury at once.

Origin able to spend up to 1,000,000 DOT from the treasury at once.