Community Members,

Due to the lack of support for Bridgehub updates from the Polkadot team, cross-chain support for BNC between Bifrost-Kusama and Bifrost-Polkadot will not be available in the short term. This directly impacts the migration timeline of vBNC and the subsequent launch of bbBNC. To ensure the planned timeline remains on track, we propose an alternative solution: a snapshot-based vBNC migration process.

This proposal outlines a detailed plan and provides clear operational guidance for community members.

TL;DR

Through a series of on-chain governance processes, we plan to migrate vBNC and its related on-chain systems from Bifrost-Kusama to Bifrost-Polkadot within one week:

• vBNC services will be paused for a few days.
• Once the migration is complete, vBNC-related services can seamlessly continue on Bifrost-Polkadot.

Background: Why a Snapshot Migration?

The official cross-chain bridge migration approach does not meet the time requirements, while using third-party bridges or developing our own poses high costs and security risks. In contrast, a snapshot-based migration is simple, reliable, and effectively addresses the current challenges.

Migration Process and Timeline

Phase 1: Initialize Polkadot-side vBNC System (By November 27)

• Deploy the vBNC function and complete initialization, temporarily restricting minting and redemption functions.

Phase 2: Suspend Kusama-side Services (November 27)

• Stop vBNC minting and redemption by adjusting parameters to reject new operations.
• Halt collator rewards and farming incentives on Kusama; return unallocated incentives via governance.
• Redeem vBNC-hosted BNC.

Phase 3: Snapshot and Asset Migration (November 28)

• Disable transfers and trading of vBNC and LP tokens on Kusama, and take a snapshot of user assets.
• Migrate unstaked BNC and LP tokens to Polkadot and issue new vBNC to match the Kusama-side snapshot.
• Create trading pairs and liquidity pools for vBNC-BNC on Polkadot.

Phase 4: Distribute New Assets and Resume Services (November 29)

• Airdrop vBNC and LP tokens to users based on the snapshot.
• Enable vBNC minting and redemption on Polkadot.

Phase 5: Post-Migration Cleanup

• Clean up residual vBNC-related data on the Kusama network.

Phase Transitions and Start Dates

We aim to minimize the transition intervals, ensuring the entire process is completed within 4–5 working days. Since the migration relies on some runtime upgrades, the process will begin as soon as Runtime 15000 is officially released, currently scheduled for November 27.

What Can Community Members Do?

Check Your Assets

Review your vBNC and related LP holdings on the Bifrost-Kusama network and keep a record. After the migration, verify your assets on the Bifrost-Polkadot side.

Unstake Your BNC

As BNC staking on Bifrost-Kusama will no longer yield rewards after the migration, users are advised to unstake manually and transfer the BNC to Bifrost-Polkadot via CEX bridges for re-staking (expected unstaking time will be reduced to 1 day during Phase 2 to facilitate migration).

Pre-Mint vBNC

To avoid potential liquidity constraints or operational inconvenience with CEX bridging, users can pre-mint vBNC on Bifrost-Kusama. During the migration, pre-minted vBNC and the corresponding underlying BNC will be migrated to Bifrost-Polkadot, saving users from manual cross-chain transfers.

Tutorial: How to Mint vBNC on Bifrost-Kusama:

https://youtu.be/TSgTShtOxPw?si=CVNLbwPKuquIFVE1

We believe this snapshot-based migration plan will effectively advance the BNC ecosystem on the Polkadot network. We welcome your feedback and suggestions!