Endur: Starknet Staking V2 upgrades

The Starknet Staking V2 upgrade is a significant enhancement to the staking mechanism of Starknet, an Ethereum Layer 2 ZK-Rollup solution, aimed at improving network participation, transparency, security, and decentralization. Introduced through the Starknet Network Improvement Proposal (SNIP) 28, it builds on the initial staking phase (Phase 1) by adding more active responsibilities for validators and refining the economic model. Below is a detailed overview based on available information:

Summary of key features of Starknet Staking V2:

1. Block Attestations for Validators:

   • Validators are now required to attest to randomly selected blocks within a specified epoch to demonstrate active participation. This allows to study validator reliability before handing over key network responsibilities to them in future phases.

   • Attestations must be submitted within a defined block window, and rewards follow an "all or nothing" model per epoch — no partial rewards are granted for failed attestations.

2. Commission Commitment Model:

   • Validators will be able to commit to a maximum commission rate (M) and a validity period (up to one year), preventing sudden commission hikes and protecting delegators. This promotes transparency and trust in the staking ecosystem.

3. Epoch-Based Structure:

   • Staking power updates are organised into epochs, providing a clear framework for validator responsibilities and reward distribution. Stake changes within an epoch will be reflected in the staking power of the following epoch.

4. Delegation switch:

   • Delegators share in the rewards proportional to their stake but on switching validator, they start earning rewards from next epoch.

Changes in Endur in this upgrade

Endur has already implemented the necessary changes and will upgrade its contracts in tandem with the Staking Protocol's mainnet upgrade. These changes have been audited, and the audit report will be published in our documentation and socials by the time the upgrade is complete.

Here are key changes in Endur contracts:

1. Unclaimed rewards are now calculated by reading each delegation contract’s rewards directly, instead of using a global index. In V1, a global index was used to track overall reward growth, but this mechanism has been deprecated in V2. Delegation contracts—internal contracts managed by Endur—are responsible for maintaining stake with the underlying staking protocol. The rewards will be claimed and staked automatically by Endur’s backend every epoch to maintain accurate exchange rate of xSTRK. Even if the backend fails, any new deposit/withdraw transaction will claim the rewards as well, ensuring the xSTRK index is always upto date.

2. We’ve renamed the amountkSTRK field in the WithdrawRequest struct to amountxSTRK. This change has no impact on on-chain state and off-chain state, unless you end up using new ABI but in code reading with old name (that would be silly :p). If your off-chain code accesses withdraw requests directly, please double check your logic is ok.

   Initially, we used kSTRK as a placeholder before finalising the name xSTRK. The old name was published by mistake and has now been corrected.

3. New methods: xSTRK (LST) contract now exposes two functions -

   1. total_delegators => reflecting the total number of internal delegation contract’s used by Endur to stake

   2. get_delegator(index) => Read delegation contract address by index

   3. unclaimed_rewards => Returns net unclaimed rewards

In summary, no action is required from end users or integrators. Everything will continue to function as it did before the upgrade.

Upgrade process

During the upgrade process, deposits and withdrawals will be temporarily paused until both the staking protocol and Endur are successfully upgraded. However, xSTRK token transfers will remain fully functional throughout.
We expect the pause to last approximately 2–4 hours, though this may vary slightly.
More details will be shared closer to the upgrade.

Conclusion

We are very excited to be part of this journey on Starknet and looking forward to fully decentralise Starknet. As always, Endur is here building for the long term.