stapel-calendar

Calendar and scheduling: events with participants and RSVP, RFC 5545 recurring series (virtual expansion, on-demand materialization, per-instant cancellation and reschedule), availability windows with free/busy and bookable slot computation, ICS export, and event-driven reminders.

Part of the Stapel framework — composable Django apps that deploy as a monolith or as microservices without changing module code.

Install

pip install stapel-calendar

At a glance

Fact	Value
Version	`0.5.0`
Python	`>=3.11` (3.11, 3.12, 3.13, 3.14)
HTTP operations	10
Config axes	1
Usage surface	31
Extension points	5
Error codes	49
Fleet dependencies	`stapel-auth` (optional) · `stapel-core` · `stapel-notifications` (optional)

Documentation

OpenAPI · capabilities.json · llms.txt (for agents)

What this is

A generic calendar core — Event / Participant / RSVP, an RFC 5545 recurrence engine (RRULE via python-dateutil, virtual expansion + on-demand materialization), availability (working windows, free/busy, slots) and ICS export. Two flavors of one domain — meetings and bookings — share this core; everything app-specific lives behind seams.

Quick start

INSTALLED_APPS = [
    # ...
    "stapel_calendar",
]

# urls.py
path("calendar/", include("stapel_calendar.urls"))

Concepts

Event — a scheduled thing (meeting/booking/appointment) with tz-aware start/end, an owner and an opaque scope_key. No FK to any host concept (org, room) — scoping and resources are seams.
Recurrence — the series master stores a canonical RRULE. Occurrences are virtual until they gain their own state (an RSVP or a resource), at which point they are materialized (persisted) on demand.
Availability — recurring working windows minus busy events give open booking slots.

from stapel_calendar import services

series = services.create_event(
    owner=user, title="Standup",
    start=start, end=end,
    recurrence_type="weekdays",            # -> FREQ=DAILY;BYDAY=MO,TU,WE,TH,FR
)
occurrences = services.expand_event(series, range_start, range_end)  # virtual
services.materialize(series, occurrence_start)  # persist one + emit hook
busy = services.free_busy(user, range_start, range_end)
slots = services.compute_slots(user, range_start, range_end, slot_minutes=30)

Settings

All configuration lives in the STAPEL_CALENDAR namespace (dict setting, flat setting, or env var — resolved lazily):

Key	Default	Meaning
`SCOPE_PROVIDER`	`…scope.DefaultScopeProvider`	Resolve/filter the opaque `scope_key`
`REMINDER_POLICY`	`…reminders.DefaultReminderPolicy`	When/what to remind
`PRESETS`	`{}`	Custom recurrence presets (merged over built-ins)
`REMINDER_OFFSETS`	`[10]`	Minutes before start to remind
`REMINDER_SCAN_WINDOW_SECONDS`	`60`	Reminder cron granularity
`DEFAULT_EXPANSION_HORIZON_DAYS`	`90`	Default range end
`MAX_EXPANSION_OCCURRENCES`	`1000`	Expansion safety cap
`DEFAULT_SLOT_MINUTES`	`30`	Default slot length

comm surface

Kind	Name	Contract
Emit	`calendar.occurrence.materialized`	An occurrence was persisted — subscribe to attach a resource
Emit	`calendar.event.reminder_due`	A reminder is due — deliver it
Function	`calendar.free_busy`	`{user_id, start, end, scope_key?}` -> `{busy: [...]}`

Extension points

See MODULE.md — the agent-facing map of every fork-free seam (the resource hook, reminder policy, scope provider, recurrence presets, serializer seams, settings).

Development

pip install -e . && pip install pytest pytest-django ruff
./setup-hooks.sh
pytest tests/

License

MIT — see LICENSE.

_{This page is assembled by stapel-readme from docs/readme.md plus the contract artifacts in docs/. Edit the prose in docs/readme.md; the badges, facts and links above and below it are generated — do not hand-edit README.md.}

Development Status
- 4 - Beta
Framework
- Django
Intended Audience
- Developers
License
- OSI Approved :: MIT License
Operating System
- OS Independent
Programming Language
Typing
- Typed

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