**ERC-4337 code at well-known addresses.** Base Sepolia (and potentially other L2s) has 23-byte Account Abstraction proxy code at ALL well-known addresses:
- Any address that "looks" like an EOA might actually have code
This breaks any contract that checks `address.code.length` to distinguish EOAs from contracts. Specifically: `feeDestinationLocked` in LiquidityManager.
**Fix pattern:** Before deploying on a forked Anvil, strip code from addresses that need to be EOAs:
**Impersonated accounts need ETH.** `anvil_impersonateAccount` lets you send from any address, but gas estimation fails if the account has 0 balance:
```bash
cast rpc --rpc-url $RPC anvil_setBalance "$ADDRESS" "0xDE0B6B3A7640000" # 1 ETH
```
**Mainnet vs Sepolia addresses differ.** Uniswap V3 contracts have different addresses per chain:
- V3 Factory: `0x33128...` (mainnet) vs `0x4752...` (Sepolia)
- SwapRouter02: `0x2626...` (mainnet) vs `0x94cC...` (Sepolia)
Always verify which chain you're forking before using hardcoded addresses.
**Docker creates root-owned files.** When forge runs inside a docker container, `cache/`, `out/`, `broadcast/` become root-owned. Subsequent runs as a non-root user fail with permission denied.