[study] (2h) Fee growth tracking — global vs inside-position, feeGrowthInside

[ozpool]

Goal

Understand how V3/V4 track LP fees efficiently.

Time estimate

2h (single focused session)

Prerequisites

• [study] (2h) Tick system — sqrtPriceX96, tick-to-price, log_1.0001 mapping #74 (F3) — Tick system — sqrtPriceX96, tick-to-price, log_1.0001 mapping
• [study] (1h) Position representation — tickLower/tickUpper/liquidity, in/out-of-range #76 (F5) — Position representation — tickLower/tickUpper/liquidity, in/out-of-range

Study plan (in order)

1. [25 min] V3 whitepaper §6.3 'Fee Growth'
2. [25 min] uniswap/v3-core: contracts/libraries/Tick.sol — getFeeGrowthInside
3. [25 min] uniswap/v3-core: contracts/libraries/Position.sol — fee crediting on update
4. [20 min] Hands-on: walk through fee accrual for a swap crossing one tick
5. [25 min] Write outcomes from memory

Total: 120 min

After studying, you can

• Distinguish feeGrowthGlobal from feeGrowthInside
• Describe per-unit-liquidity fee accrual semantics
• Trace how a position claims accrued fees on the next modifyPosition
• Explain the gas savings vs per-position update on every swap

Tradeoff prompt for the architectural review

Why doesn't fee tracking require per-position state updates on every swap?

References

• uniswap/v3-core Tick.sol + Position.sol
• Uniswap V3 whitepaper §6.3