This procedural macro crate provides `#[derive(XmlDeserialize, XmlSerialize)]` for automatically generating XML serialization/deserialization code for Rust structs and enums. It supports attributes for namespace, renaming, and type mapping, reducing boilerplate in WebDAV XML handling. The implementation is non-obvious, handling untagged variants, nested namespaces, and custom type conversions. It is a high-craftsmanship component that could be extracted for any XML-heavy Rust project requiring a serde-like experience.

The `rustical_store` crate defines the core storage traits (`CalendarReadStore`, `CalendarWriteStore`, `AddressbookReadStore`, `AddressbookWriteStore`, `AuthenticationProvider`) that decouple protocol logic from backend implementation. This pattern enables swapping SQLite for other databases (e.g., PostgreSQL) without modifying the DAV handlers. The traits are async, use associated types for errors, and follow a resource-oriented design. This is a clean, reusable abstraction for any service needing pluggable persistence.

The `Resource` trait and `ResourceService` struct provide a generic framework for handling WebDAV operations (PROPFIND, PROPPATCH, DELETE, MOVE, COPY) on hierarchical resources. It encapsulates common logic like depth handling, locking, and XML multistatus responses, and allows concrete implementations for calendars and addressbooks. This pattern simplifies adding new resource types and demonstrates a clean separation of protocol concerns.

The `SqliteCalendarStore` implements the calendar storage traits with a well-designed schema tracking changes via `calendarobjectchangelog` table and monotonically increasing sync tokens. It supports pagination, soft-delete (trashbin), pruning of old data, and repair operations. The implementation uses transactional `BEGIN IMMEDIATE` to avoid write conflicts and includes a `skip_broken` flag for graceful malformed object handling. This is a robust, reusable persistence layer for any sync-oriented application.