# iCloud Calendar MCP

A self-hosted iCloud Calendar service for ChatGPT and other remote MCP clients.
It uses iCloud CalDAV, OAuth, server-side write controls, and Cloudflare Tunnel.

**Status:** Initial implementation. Offline tests cover access and write controls.
Live iCloud access, the full ChatGPT OAuth flow, and devbox deployment are not yet verified.

## Tools

| Tool | Function |
| --- | --- |
| `get_profile` | Identify the permitted account connection |
| `list_calendars` | List readable calendars and enabled write operations |
| `search_events` | Read or search a window of at most 93 days |
| `get_event` | Read an event resource and its ETag |
| `create_event` | Create one timed or all-day event |
| `update_event` | Update one simple event with an ETag check |

Recurring events can be read. Their expanded occurrences share the resource event ID;
the `recurrence_id` identifies an occurrence. This version does not write recurrence,
invitations, RSVP responses, or deletions. Search reports truncation and skipped resources.
Free-time calculation and pagination are planned.

## Access controls

Each installation supports one Apple account and one permitted OAuth subject.
OAuth grants access to this service. The Apple app-specific password grants the
service access to iCloud. These are separate credentials.

The service requires HTTPS configuration, signed tokens for its exact resource,
and `calendar:read`. Writes also require `calendar:write`, an exact writable calendar
ID, and an enabled operation. Writes are disabled until the operator sets that policy.
There is no unauthenticated mode. See [SECURITY.md](SECURITY.md).

## Develop

Use Python 3.12 or later and uv 0.12.22:

```sh
uv sync --locked --extra test
uv run --locked pytest -q
uv run --locked ruff check src tests
```

Tests use generated signing keys and fake calendars. They do not access real accounts.
The HTTP tests run in memory without a network listener.

## Host on the devbox

See [the Cloudflare setup guide](docs/deployment.md). The repository contains a
container definition, Compose configuration, a tunnel ingress example, and a
non-secret environment template. These files do not deploy or connect an account.

First configure an OAuth issuer, the public hostname, and the permitted subject.
Enter the Apple app-specific password only through a secure host setup process.
Never enter it in chat. Then test a separate calendar before enabling normal writes.

## Next work

1. Choose and configure the OAuth issuer and exact ChatGPT callback.
2. Verify the container and Cloudflare route on the devbox.
3. Verify login and calendar reads with ChatGPT.
4. Verify conditional writes in a test calendar.
5. Add free-time calculation, result pagination, and request limits.
6. Add separate user connections and encrypted secret storage before shared hosting.

Open-source code can be self-hosted per user now. Shared public hosting needs further work.

## Sources and license

This service reuses CalDAV discovery and resource code from
[duanefields/dav-mcp](https://github.com/duanefields/dav-mcp).
See [THIRD_PARTY_NOTICES.md](THIRD_PARTY_NOTICES.md).

- [Apple app-specific passwords](https://support.apple.com/en-us/102654)
- [OpenAI MCP authentication](https://developers.openai.com/apps-sdk/build/auth)
- [ChatGPT developer mode](https://developers.openai.com/api/docs/guides/developer-mode)
- [FastMCP remote OAuth](https://gofastmcp.com/servers/auth/remote-oauth)
- [Cloudflare Tunnel](https://developers.cloudflare.com/tunnel/)

MIT license. This is an independent project. Apple and OpenAI do not endorse it.