Architecture

The full picture

Only SnowballToken and FeeRouter talk to each other and to PancakeSwap. SnowballRegistry is deliberately standalone: it's a listing directory, not a financial pipe (more on why in Fee & Burn Mechanics).

Why FeeRouter is a separate contract, not built into the token

Keeping the swap/LP logic out of SnowballToken keeps the token's transfer hook trivial: it either takes a fee and forwards it, or it doesn't. No external calls, no swap logic, no reentrancy surface inside _update. All the complexity, and all the external calls to PancakeSwap, live in FeeRouter, guarded separately by a reentrancy lock and a caller gate. It also means FeeRouter can be configured to burn fees from other registered tokens too, without touching SnowballToken at all. See Fee & Burn Mechanics.

Where it lives

• contracts/src/SnowballToken.sol
• contracts/src/FeeRouter.sol
• contracts/src/SnowballRegistry.sol
• contracts/src/interfaces/IPancakeRouter02.sol, IPancakeFactory.sol
• contracts/script/Deploy.s.sol