Cross-Chain Bridge & Routing
To enable seamless multi-chain ticket purchases, QanVault integrates Symbiosis Finance, a decentralized cross-chain liquidity protocol that pools liquidity across EVM networks.
This document details how Ethereum ticket payments are routed, bridged, and settled into the canonical BSC prize contract.
Why a Cross-Chain Bridge is Required#
Because all draw contracts, ticket indexing, and prize pots reside canonically on BNB Smart Chain, any ticket purchased using Ethereum assets (native ETH, ERC-20 USDT, or Ethereum QANX) must have its corresponding value rebalanced onto BNB Smart Chain to maintain 100% solvency.
Without a bridge, Ethereum funds would sit trapped on Ethereum while BSC prize pools would be underfunded.
The 1.0% Bridge Fee Subsidy#
Standard retail cross-chain bridges often charge 3.0% to 3.5% in combined swap spreads and relayer fees when transferring tokens between Ethereum and BNB Smart Chain.
To protect players from excessive bridging costs:
- QanVault fixes the bridge fee for Ethereum participants at an immutable 1.0%.
- Any delta between the 1.0% fee and market relayer fees is absorbed by the protocol's operations and routing reserve.
- Players choosing BNB Smart Chain pay 0.0% in bridge fees, as no cross-chain transfer is needed.
Multi-Chain Fee Comparison
| Chain Chosen | Payment Currency | Bridge Fee | Network Gas | Settlement Destination |
|---|---|---|---|---|
| BNB Smart Chain | QANX (BEP-20) | 0.0% | ~$0.02 | BSC (Immediate) |
| BNB Smart Chain | BNB or BEP-20 USDT | 0.0% | ~$0.05 | BSC (Immediate) |
| BNB Smart Chain | Any Liquid BEP-20 Token | 0.0% | ~$0.05 | BSC (Immediate via PancakeSwap) |
| Ethereum | ETH or ERC-20 USDT | 1.0% | ~$3.00 to $8.00 | BSC (Batched via Symbiosis) |
| Ethereum | QANX (ERC-20) | 1.0% | ~$3.00 to $8.00 | BSC (Batched via Symbiosis) |
| Ethereum | Any Liquid ERC-20 Token | 1.0% | ~$3.00 to $8.00 | BSC (Uniswap + Symbiosis) |
The $2,500 Batching Liquidity Gate#
Initiating an individual cross-chain bridge transaction for every single $12.40 ticket purchase would consume significant Ethereum L1 gas, resulting in unnecessary deadweight cost.
To optimize gas efficiency:
- Escrow Accumulation: Ethereum ticket receipts accumulate in a secure on-chain routing escrow contract.
- Threshold Trigger: The keeper triggers a batch bridge transaction via Symbiosis whenever accumulated escrow reaches $2,500 USD (approximately 200,000 QANX).
- Daily Cutoff Fallback: Regardless of volume, any accumulated Ethereum balance is bridged automatically at 23:00:00 UTC (one hour before the daily draw cutoff), guaranteeing that 100% of day D's proceeds are bridged and deposited into the BSC prize pool before the draw commits.
Bridge Duration & Finality#
- Average Bridge Time: 3 to 15 minutes.
- Ethereum Finality: Symbiosis waits for 64 Ethereum block confirmations (approximately 12.8 minutes) to protect against L1 reorganizations.
- Canonical Ticket Minting Lifecycle: Once your Ethereum transaction confirms, the frontend interface acknowledges your purchase order in "Relaying" state. The official ticket IDs and ranges are permanently recorded into the canonical BSC prize contract as soon as the bridge transaction executes on BNB Smart Chain. Any purchase submitted before the 23:00:00 UTC daily batch cutoff is guaranteed to bridge and mint on BSC before the 23:59:59 UTC daily draw cutoff.
Slippage & Dust Refund Guarantee#
When exchanging ETH or USDT into QANX through Uniswap v3 prior to bridging:
- The quote engine enforces a strict 1.0% maximum slippage tolerance.
- Any unspent token dust resulting from favorable execution price movements is refunded directly back to the player's wallet in the same transaction.
Next Steps#
- Learn about DEX swap mechanics: USDT & DEX Swaps
- Complete technical architecture: System Architecture