Welcome

Lumen is an iOS browser that reads along with you. Every page you engage with becomes part of a private knowledge base you can ask questions about. There is no cloud, no account, no server. Just the phone in your hand.

This document covers how Lumen works in detail, how to build it from source, and how to think about contributing. It is ordered so that you can read it straight through and come away with a complete mental model, or jump to a section from the sidebar when you have a specific question.

Philosophy

The web remembers for you until it doesn’t. Browsers forget history on a schedule, bookmarks go stale, and cloud notes get scattered across apps. Lumen keeps a quiet, local record of what you actually read so you can ask it back later. The record never leaves the device.

Our position is that a browser should be the memory of your reading, not the distribution channel for it. That position determines almost every other design choice: the model runs locally, the database stays sandboxed, the site menu is honest about what was scrubbed, and there is nothing to sign in to.

Next steps

• Installation if you want to install Lumen on a device.
• Knowledge panel for how Ask and Library work.
• Privacy for the on-device guarantees.
• Architecture for the technical shape of the app.
• Contributing if you want to work on the code.