Upgrade Strategies

This guide explains recommended upgrade strategies for UUPS upgradeable contracts used in this project.

UUPS Pattern (used by MetaTxGateway)

• Implementation contract contains the logic and an _authorizeUpgrade function guarded by owner access.

• A minimal proxy (ERC1967) holds storage and delegates calls to the implementation.

Best Practices

1. Access control for upgrades

   • Only a secure multisig / DAO-controlled address should be owner and allowed to authorize upgrades.

2. Upgrade process

   • Write a migration script that:

     • Deploys new implementation.

     • Runs on-chain tests against a staging proxy (optional).

     • Calls the proxy upgrade via a signed multisig transaction.

   • Verify the new implementation on block explorers.

3. Backwards-compatible changes

   • Prefer additive changes (new functions, new storage at the end).

   • Avoid changing existing storage layout; if absolutely necessary, write careful migration logic.

4. Tests and gating

   • Unit and integration tests that exercise state migration.

   • Automated upgrade simulation (fork mainnet and test upgrade).

   • Manual review and security audit for any upgrade touching critical logic.

Upgrade Safety Checklist

• Confirm _authorizeUpgrade is restricted to multisig/DAO.

• Validate storage layout (use tools like OpenZeppelin upgrades plugin).

• Run full test suite on a fork of the mainnet with real state, when applicable.

• Produce a migration script; include rollback strategy where possible.

• Announce upgrade windows and maintain monitoring during/after upgrade.

Emergency Process

• Pause contract operations if the new implementation introduces issues.

• If multisig is compromised, follow governance emergency protocol (revoke compromised keys, rotate owners).

Notes on Proxy Storage

• Use explicit storage gaps only when necessary and document any reserved slots.

• For safe storage changes: add new variables at the end of storage structs and test thoroughly.