Privacy

Effective 3 September 2026

Sereno runs entirely on your own Mac. There is no Sereno server. No backend exists for your messages to pass through, so none of this is a promise about how carefully someone stores your data. There is nowhere for it to be stored.

What Sereno keeps, and where

All of it is on your Mac:

• Your Slack access token, in the macOS Keychain, service com.rhystart.sereno.
• Your to-do list, and the message text it was derived from, in ~/Library/Application Support/Sereno/state.json.
• Your settings, including the role description you write and the city you pick, in macOS UserDefaults.

To remove it: disconnect Slack in Settings, which deletes the token, then delete that state.json file.

What Slack permissions Sereno asks for

Read-only, and only these:

• channels:history groups:history im:history mpim:history Message text, in conversations you are already in.
• channels:read groups:read im:read mpim:read Conversation names and membership.
• users:read usergroups:read Display names, so Sereno can tell whether a message is aimed at you.

Sereno cannot post, edit, delete, or schedule anything in Slack. It holds no permission that would allow it. It signs in with PKCE, so the app contains no client secret and the token is issued to you rather than to a shared server.

What leaves your Mac

Two destinations, and nothing else.

Slack. Sereno reads your conversations through Slack's API, as you, using the token you granted.

Open-Meteo, only if you switch the weather display on. The city name you type goes to geocoding-api.open-meteo.com once, to turn it into coordinates. Those coordinates then go to api.open-meteo.com when the forecast refreshes. Sereno does not use Core Location and never asks your Mac where it is, so the only location involved is the city you chose. With the weather toggle off, nothing is sent. Open-Meteo needs no account and no API key, so these requests carry nothing that identifies you.

Apple Reminders is not a network destination, but worth naming: exporting an item writes to your local Reminders database. If your Reminders account syncs through iCloud, that reminder syncs with it, under Apple's privacy policy rather than this one.

What does not leave your Mac

The ranking runs on Apple's on-device foundation model, through the FoundationModels framework. Your message text is processed locally. It is not sent to Anthropic, OpenAI, Apple, or anyone else for that purpose.

Sereno contains no analytics, no telemetry, no crash reporting, and no third-party SDKs. It does not phone home, and it has no update checker.

Logging

Sereno writes diagnostic logs to the macOS unified log, under the subsystem com.rhystart.sereno. Message text, sender and channel names, permalinks, and your city are either marked private or never logged at all. The token is never logged. These logs stay on your Mac.

Your workspace administrator

If your workspace requires approval for app installations, your administrator sees Sereno's requested permissions before you can connect. They can revoke its access at any time from Slack's own settings, which immediately stops it reading anything.

Children

Sereno is a workplace tool and is not directed at children under 13.

Changes

Material changes appear on this page with a new date at the top.

Contact

Open an issue on GitHub, or email info@rhystart.com. Security reports go to the same address, and the security policy says what to expect.