General Review Guidelines for AI Agents

When interacting with times, use chrono crate and UTC. Avoid SystemTime.
Never have a message or error attribute name for any variant of any error enums. When UniFFI generates Kotlin exception classes, they inherit from kotlin.Exception which has a message attribute, having a duplicate one creates conflicts in Kotlin; error gets translated into the native Exception class.
Using #[error(transparent)] without #[uniffi(flat_error)] is not a good idea as UniFFI does not support re-using types across different error enums at least on Kotlin.

Module-specific Guidelines

Ensure that the TransactionTypeId is never re-ordered. Only additive changes are allowed or this would break all past transactions handling.