Maintain Compatibility

Build for interoperability. Before implementing a facet or feature, identify existing standards and expected behaviors, and ensure your implementation behaves the same where it matters. Code style can differ; externally observable behavior should not.

Implementation checklist:

1. Standards: Check relevant ERC standards. Implement required and optional parts precisely (function signatures, return values, events, errors, and revert conditions).
2. Established libraries: If a widely used library like OpenZeppelin implements the feature, match its externally visible behavior (event names and order, error messages or custom errors). Use judgment—only mirror behaviors that matter for compatibility.
3. Ecosystem expectations: Marketplaces, wallets, indexers, DAOs, and voting systems often rely on specific interfaces and behaviors (for example ERC-165 detection, approvals, metadata). Match these expectations unless there is a strong reason not to.

Avoid surprising users. If you must deviate, document the differences and rationale, and add tests to prove compatibility where applicable.