Feature request: Add support for rfc7265

[allenporter]

As we're reviewing additional RFCs to support https://datatracker.ietf.org/doc/html/rfc7265 looks straight forward.

We already have a nice parsing tree structure that will make it trivial to convert to this format.

[allenporter]

Overview & Background

RFC 7265 (jCal: The JSON Format for iCalendar) defines a standardized, lossless 1-to-1 JSON representation of RFC 5545 iCalendar objects. Unlike JSCalendar (RFC 8984) which introduces a revamped data model, jCal is an alternative wire-format serialization that preserves the exact RFC 5545 component/property/parameter tree structure.

This is particularly useful for:

• CalDAV JSON wire protocols (e.g. JSON-based PROPFIND / REPORT in WebDAV/CalDAV servers and clients like icaldav).
• Web/REST APIs consuming or producing calendar payloads in standard JSON without custom schema translation.

---

jCal Data Structure (RFC 7265 §3)

Every iCalendar component is represented as a 3-element JSON array:

[
  "component_name",
  [
    [ "prop_name", { "param_key": "param_val" }, "data_type", value1, ... ],
    ...
  ],
  [
    [ "subcomponent_name", [ ...properties... ], [ ...subcomponents... ] ],
    ...
  ]
]

Example (VEVENT in jCal)

[
  "vcalendar",
  [
    ["prodid", {}, "text", "-//Example Corp.//EN"],
    ["version", {}, "text", "2.0"]
  ],
  [
    [
      "vevent",
      [
        ["uid", {}, "text", "event-123@example.com"],
        ["dtstamp", {}, "date-time", "2026-08-24T12:00:00Z"],
        ["dtstart", {}, "date-time", "2026-08-24T14:00:00Z"],
        ["summary", {}, "text", "Architecture Review"],
        ["sequence", {}, "integer", 0],
        ["geo", {}, "float", [37.386013, -122.082932]],
        [
          "rrule",
          {},
          "recur",
          {
            "freq": "WEEKLY",
            "count": 10,
            "byday": ["MO", "WE"]
          }
        ],
        [
          "attendee",
          { "cn": "Alice Smith", "role": "REQ-PARTICIPANT" },
          "cal-address",
          "mailto:alice@example.com"
        ]
      ],
      []
    ]
  ]
]

---

Proposed API in ical

1. High-Level Calendar / Stream API (ical.calendar_stream / ical.jcal)

from ical.calendar import Calendar
from ical.calendar_stream import IcsCalendarStream, JcalCalendarStream

# Parse from jCal JSON structure, string, or bytes
cal = JcalCalendarStream.calendar_from_jcal(jcal_json_or_obj)

# Export Calendar model to jCal JSON structure
jcal_data = cal.as_jcal()  # returns 3-element list ['vcalendar', [...props], [...subcomps]]

# Direct lossless conversion between wire formats
ics_text = JcalCalendarStream.jcal_to_ics(jcal_data)
jcal_data = JcalCalendarStream.ics_to_jcal(ics_text)

2. Component & Type Level Converters

Leverage ical's existing parsing and type system (ical.parsing.property.parse_contentlines, ParsedProperty, Recur, Geo, UtcOffset):

• Recur (RRULE) $\leftrightarrow$ {"freq": "WEEKLY", "count": 10, "byday": ["MO", "WE"], "until": "..."}
• Geo $\leftrightarrow$ [latitude, longitude] float pair
• UtcOffset $\leftrightarrow$ "+05:00" ISO offset
• Date / DateTime $\leftrightarrow$ ISO 8601 strings (YYYY-MM-DD / YYYY-MM-DDTHH:MM:SSZ)
• Typed Property Values: Explicit conversion for "integer" (int), "float" (float), "boolean" (bool), "text" (unescaped string).

---

Implementation Considerations

1. ical already possesses robust RFC 5545 line unfolding, parameter parsing (with quoted values and delimiters), and typed Pydantic models.
2. Building JcalCalendarStream on top of ical.parsing.property or CalendarStream allows 100% type safety and lossless round-tripping.
3. This provides complete calendar format coverage for ical alongside ICS (RFC 5545) and JSCalendar (RFC 8984 / Feature request: Add support for JSCalendar (RFC 8984) #650).