Contracts

The protocol stacks into five horizontal layers, from upgrade control at the top to external integrations at the bottom.

Layer	Contracts	Responsibility
Proxy	ProxyAdmin	Owns all upgradeable proxies. Multisig-controlled. Enables upgrades without state migration
Access control	ZothAccessControl, FunctionsAccessControl	Single source of truth for roles. ZothAccessControl governs vault and token roles; FunctionsAccessControl governs oracle roles
Token and oracle	zTOKEN, PriceOracle	The ERC-20 NAV-share token (upgradeable) and the non-upgradeable NAV price feed
Vault layer	DepositVault, RedemptionVault	DepositVault mints the zTOKEN against deposits; RedemptionVault burns it and returns deposit asset
External	Screener	Screens addresses and correctly identifies risks before authorizing transactions

Contract	Type	Upgradeable	Purpose
ZothAccessControl	Access	Yes (proxy)	Central role management for all contracts
zTOKEN	Token	Yes (proxy)	ERC-20 interest-bearing token with compliance controls
DepositVault	Vault	Yes (proxy)	Accepts deposits, mints the zTOKEN
RedemptionVault	Vault	Yes (proxy)	Burns the zTOKEN, returns deposit assets
PriceOracle	Oracle	No	NAV price feed with tolerance and staleness checks
FunctionsAccessControl	Access	No	Role management scoped to the oracle
ProxyAdmin	Admin	No	Controls all proxy upgrades