Tidefern

Overview

I'm building Tidefern as its founder and product engineer. It's a cycle, pregnancy, and family tracking product. Sharing needs more detail than a relationship label: someone might share a summary with a partner while keeping their journal private.

The public site is live. The first phase includes the domain model, API, security foundation, and design reference. I'm still building the authenticated Today, calendar, journey, family, and sharing screens.

Sharing with a scope

The policy checks the person making a request against its action and resource category, using grants with summary, read, or contribute access and, for child-related grants, a specific child ID. Private journal entries stay outside sharing grants.

A grant can be revoked.

The policy lives below the interface, where every API consumer can use the same rules. Screens can explain someone's access without having to define it themselves.

Protecting the data

Private free text uses application-layer envelope encryption with versioned keys. The service can decrypt stored content for authorized requests, so this isn't end-to-end encryption. Reminder emails use generic notices and keep sensitive entries out of the message.

A product foundation

The web app uses Next.js and TypeScript, with a Hono API, PostgreSQL, Drizzle, Better Auth, and a typed client generated around an OpenAPI contract. The working design reference includes exported tokens and light and dark states, with chapters covering color, typography, components, motion, and sound.

The next milestone connects the API to the everyday screens, followed by a complete walkthrough of those flows.