# Parser Compatibility Notes

## XML

`fast-xml-parser` is used for DAV XML parsing and serialization. The compatibility
helper parses with `preserveOrder`, keeps qualified names and namespace
declarations, disables entity processing, rejects `DOCTYPE` and `ENTITY`
declarations before parsing, and stores dead-property XML as the original
fragment.

## iCalendar and vCard

No additional iCalendar, recurrence, or vCard parser dependency is selected at
the foundation stage. The npm ecosystem options reviewed during the compatibility
check did not justify adding another protocol parser before the storage/report
implementation.

Calendar and address book storage now use bounded local parsers for the v1
surface. The iCalendar parser accepts a single `VCALENDAR` with one `VEVENT`,
`VTODO`, or `VJOURNAL`, validates UID/component structure, normalizes UTF-8/CRLF,
and enforces configured recurrence bounds. The vCard parser accepts one `VCARD`,
requires UID and VERSION 3.0 or 4.0, normalizes UTF-8/CRLF, and keeps body storage
bounded by configuration.