Hubble: open-source markdown notes app built to be edited by humans and AI agents

Hubble is a self-hostable, open-source notetaking tool that stores everything as plain markdown files, positioned explicitly for a workflow shared between a person and their AI agents. The landing page shows a working notebook rather than describing the product in prose: a directory of note files (desert-stars.md, tokyo-ramen.md, dune.md, sourdough.md and others) sit alongside HTML views like index.html, bookshelf.html and map.html, implying the app renders the same underlying files into browsable pages such as a bookshelf and a map.

The appeal of the plain-file approach is that notes stay in an open, portable format an agent can read and write directly, with no proprietary database in the way. The interface hints at agent participation — a prompt line and a status message noting that ideas were appended for next time — suggesting agents can add to or maintain your notes as part of a normal session.

Beyond that, the page itself carries little substantive detail: no architecture, license specifics, or agent-integration mechanics are spelled out in the captured content. The takeaway is the concept — a markdown-first, human-and-agent notebook — as an example of the growing trend toward tools designed so that AI assistants and their users operate on the same open data.