hermes-yandex-calendar 0.2.0

Yandex Calendar plugin for Hermes Agent: list, create, update, RSVP, move, and delete events over CalDAV.

hermes-yandex-calendar

Let your Hermes Agent run your Yandex Calendar. "What's on my calendar next week?" — "Move the standup to Thursday and invite Ann." — "Decline the 4pm." The agent reads and writes real events on your real calendar, over CalDAV, with no third-party service in the middle.

• 📅 Seven tools, one toolset — list, create, update, RSVP, move between calendars, delete, and enumerate the calendars themselves.
• 🔒 You choose what it may touch — restrict it to specific calendars, and to specific actions (read, read,write, …). A disallowed action is not in the toolset at all.
• 🛟 Careful with your data — recurrence rules, alarms, and properties this plugin does not model survive every edit; moves copy the resource byte for byte; an event is deleted only after its copy is safely in place.
• 🔑 App password, not your account password — scoped to CalDAV, revocable in one click.

Tested against Hermes 0.19.x, Python 3.11–3.13.

Quick start

# 1. Install into Hermes (alternatively: pip install hermes-yandex-calendar)
hermes plugins install akinfold/hermes-yandex-calendar --enable

# 2. Add your credentials — the app password comes from
#    https://id.yandex.ru/security/app-passwords (scope: "Calendar (CalDAV)")
printf 'YANDEX_CALENDAR_LOGIN=%s\nYANDEX_CALENDAR_APP_PASSWORD=%s\n' \
  '[e-mail]' 'your-app-password' >> ~/.hermes/.env

Then enable it in ~/.hermes/config.yaml (third-party plugins are off by default):

plugins:
  enabled: [yandex_calendar]

That's it. Ask the agent "what do I have tomorrow?" and it will tell you.

Not ready to hand over write access? Add YANDEX_CALENDAR_ACTIONS=read and it can only look — see Restricting what the agent can do.

The tools

Up to seven standalone tools, in the yandex_calendar toolset:

Tool	Purpose
yandex_calendar_list_calendars	List the calendars the plugin can use (name + href).
yandex_calendar_list_events	List events in a time range (summary, start/end, location, description, attendees, busy status, and an href).
yandex_calendar_create_event	Create an event (summary, start, optional end/location/description/all-day, attendees, busy status, target calendar).
yandex_calendar_update_event	Edit an event by href: change fields, add/remove attendees, toggle busy/free. Recurrence rules and alarms are preserved.
yandex_calendar_respond_event	Respond to a meeting invitation — accept, decline, or tentatively accept.
yandex_calendar_move_event	Move an event to another calendar, contents intact.
yandex_calendar_delete_event	Delete an event by href.

Yandex Calendar has no public REST API, so this plugin speaks CalDAV (https://caldav.yandex.ru) directly — the same protocol Yandex's own docs point third-party clients at. Nothing is proxied through anyone else's servers.

Multiple calendars

Every tool that reads or writes events takes an optional calendar argument — a calendar name (as returned by yandex_calendar_list_calendars) or its href. Omit it to use the default (first) calendar. update, move, and delete identify the event by its href, which already encodes the calendar it lives in.

Restrict which calendars the plugin may touch with YANDEX_CALENDAR_CALENDARS; the first one in that list becomes the default.

Configuration

Env var	Required	Default	Meaning
YANDEX_CALENDAR_LOGIN	yes	—	Yandex login / email.
YANDEX_CALENDAR_APP_PASSWORD	yes	—	App password for CalDAV — an account password will not work.
YANDEX_CALENDAR_BASE_URL	no	https://caldav.yandex.ru	Override for self-hosted / testing.
YANDEX_CALENDAR_CALENDARS	no	(all)	Comma-separated allow-list of calendar names, e.g. Work,Personal. The first is the default calendar.
YANDEX_CALENDAR_ACTIONS	no	(all)	Comma-separated allow-list of actions the agent may perform — see below.

Credentials are read from the environment first, then from ~/.hermes/.env, so they work in gateway and subprocess runs. Secret values are never logged.

Dates and times are ISO 8601 (2026-07-25 or 2026-07-25T14:00:00+03:00); a datetime without an offset is treated as UTC.

Restricting what the agent can do

YANDEX_CALENDAR_ACTIONS decides which of the seven tools are registered at all. A disallowed action is not merely refused at call time: the tool never appears in the agent's toolset, so it cannot be invoked, and the model is not tempted to try.

Accepted values, comma-separated and case-insensitive — individual actions (list_calendars, list_events, create_event, update_event, respond_event, move_event, delete_event), full tool names (yandex_calendar_delete_event), or the shorthands:

Shorthand	Expands to
read	list_calendars, list_events
write	create_event, update_event, respond_event, move_event
delete	delete_event
all	everything (the default)

# Look, but don't touch:
YANDEX_CALENDAR_ACTIONS=read

# Full scheduling, but the agent can never delete anything:
YANDEX_CALENDAR_ACTIONS=read,write

# Just enough to answer invitations:
YANDEX_CALENDAR_ACTIONS=list_events,respond_event

Leave it unset for all seven tools. A name that matches nothing is ignored, so a typo can only ever withhold a tool, never grant one — and a value that names nothing recognisable therefore registers nothing at all. The list is applied when the plugin loads: restart Hermes after changing it.

Getting the app password

CalDAV does not accept your normal account password.

1. Open https://id.yandex.ru/security/app-passwords.
2. Add a password with the Calendar (CalDAV) scope.
3. Copy it into YANDEX_CALENDAR_APP_PASSWORD — it is shown only once, and you can revoke it at any time without touching your account password.

If a tool answers "Authentication failed", this is almost always the cause.

Installing the plugin into Hermes

Option A — from Git (recommended)

hermes plugins install akinfold/hermes-yandex-calendar --enable

Option B — pip

pip install hermes-yandex-calendar

Hermes discovers it through the hermes_agent.plugins entry point; add yandex_calendar to plugins.enabled.

Option C — drop-in directory

Unzip the release archive into ~/.hermes/plugins/ so you end up with ~/.hermes/plugins/yandex_calendar/plugin.yaml, then enable it the same way.

Development

python -m venv .venv && source .venv/bin/activate
pip install -e '.[dev]'
ruff check . && ruff format --check .
pytest                       # unit tests, no network

Running the live E2E tests

The e2e-marked tests hit a real Yandex account and are deselected by default. They create, edit, and then delete a throwaway event 400 days out, so a successful run leaves nothing behind — but the attendees they invite do receive an invitation, so use addresses you own.

Locally

YANDEX_CALENDAR_LOGIN=[e-mail] \
YANDEX_CALENDAR_APP_PASSWORD=xxxx \
pytest -m e2e

Or keep the credentials in ~/.yandex-calendar-login and ~/.yandex-calendar-app-password (plus optional ~/.yandex-calendar-attendees) and just run pytest -m e2e — see tests/e2e/conftest.py.

On GitHub Actions

The E2E (live) workflow is manual (workflow_dispatch). It reads YANDEX_CALENDAR_LOGIN, YANDEX_CALENDAR_APP_PASSWORD, and YC_E2E_ATTENDEES from a GitHub Environment named yandex-calendar-e2e.

Contributing

Issues and PRs are welcome — see CONTRIBUTING.md for the layout, the plugin contract rules worth knowing, and the release process.

License

MIT — see LICENSE.