The brain
The brain is a small service on your server. Each person has an account and a database of their own; every Claude they use connects to it — the Claude apps and claude.ai as a custom connector, Claude Code and Claude Desktop as a remote MCP server — and their machines with a personal token.
What it keeps
Section titled “What it keeps”- Documents — Markdown with a path, linked with
[[target]]as Obsidian writes them, in seven areas: who you are, projects, clients, people, notes, a diary, an inbox. - History — every write keeps the version it replaces, with who made it and when. Anything can be read as it was and put back.
- Tasks — one document per task, one list for every chat, the console and the web board.
- Search — full text and by meaning, fused; the embeddings are computed by a model on the same server.
Claude writes without asking, so the rules are enforced by the service and a write that breaks one is refused with the reasons: one subject per page, a title and a sentence saying what it is, at least one link, no near copies, no secrets.
Who gets in
Section titled “Who gets in”Accounts exist only by invitation. Signing in takes the account, a passphrase and a TOTP code. Claude connects through OAuth 2.1 with PKCE; machines get a personal token by signing in. Tokens are stored as hashes; TOTP secrets and backup keys are encrypted with a key that exists only on the server.
Backups
Section titled “Backups”Your machines check every half hour whether the brain changed and fetch a copy only when it did, sealed with your own backup key. No third party holds the brain.