Uniswap V3 Integration

Eloqura uses Uniswap V3 on Sepolia as a fallback quote and swap router for tokens without Eloqura V2 pools.

Overview

When a direct Eloqura V2 pool doesn't exist or has insufficient liquidity, the swap page falls back to Uniswap V3's QuoterV2 for price discovery and SwapRouter02 for execution.

Fee Tiers

Uniswap V3 pools are deployed at specific fee levels. The quote system tries all four:

Tier	Fee (bps)	Fee %	Typical Use
LOWEST	100	0.01%	Stablecoin pairs
LOW	500	0.05%	Correlated pairs
MEDIUM	3000	0.30%	Most pairs
HIGH	10000	1.00%	Exotic/volatile pairs

Quote Flow

1. Try all 4 fee tiers via QuoterV2.quoteExactInputSingle()
2. Select the tier with the best output amount
3. Store bestFeeTier in the quote object
4. Pass bestFeeTier to swap execution

Fee Tier Mismatch Bug: The swap execution MUST use the same fee tier that produced the best quote. Never hardcode a default. Different pairs use different fee tiers, and mismatches cause transaction reverts.

Multi-Hop Fallback

If no direct pool exists on Uniswap V3 either, the system tries a multi-hop route:

Token → WETH → USDC

This catches most tokens that have WETH liquidity on Uniswap V3.

Contract Functions Used

QuoterV2

Function	Description
quoteExactInputSingle(params)	Get output amount for input

SwapRouter02

Function	Description
exactInputSingle(params)	Execute single-hop swap
multicall(data[])	Batch multiple operations

Known Pitfalls

• parseUnits overflow: JavaScript floats produce excess decimals. Always .toFixed(token.decimals) before parseUnits().

• RPC getLogs limits: Public Sepolia RPCs limit eth_getLogs to ~5000 blocks per request. Chunk larger ranges.