Cairn

One private memory, shared by the AI tools you choose.

Cairn keeps the background you keep repeating — your projects, decisions, and preferences — in one private place you control, and lets the AI tools you authorize look up only the parts they need.

Cairn is a working name, chosen so implementation could proceed. It is not an approved brand. Everything user-visible comes from packages/config/src/product.ts.

Run it

pnpm install
pnpm setup      # generates a local encryption key and creates the database
pnpm demo:seed  # optional: fills it with an example project
pnpm dev        # http://localhost:3000

No account, API key, or cloud service is required. Sign in with any email address; the code is printed by the server rather than emailed, and the interface says so.

Requires Node 20.9+ and pnpm 9. The local database is a real PostgreSQL build (PGlite) that runs in-process — no Docker, no server to install.

Related MCP server: engram

What it does

1. You add something: paste a note, upload a document, or read a web page.

2. It finds the things worth remembering and shows you each one, with the exact sentence it came from.

3. You keep, reword, or throw away anything. Nothing is saved until you keep it.

4. You ask questions, and every answer shows its sources.

5. If you want, you connect an AI tool. It can look up only what you saved, and you can turn it off at any time.

Everything you keep is stored as ordinary Markdown you can download at any moment, and the whole workspace can be deleted in one step.

Checks

pnpm verify

Runs format, lint, typecheck, unit tests, integration tests, security tests, MCP contract tests, and a production build. Browser tests run separately:

pnpm test:e2e:install   # once
pnpm test:e2e

Layout

apps/web             the website and its application API
apps/worker          the background worker (needs a PostgreSQL database)
packages/domain      entities, policies, and every external interface
packages/db          schema, reviewed SQL migrations, repositories, tenancy
packages/crypto      envelope encryption and key providers
packages/vault       versioned Markdown, export, backup, restore
packages/search      embeddings, retrieval, citations, answers
packages/ingestion   normalize, chunk, extract, reconcile, jobs
packages/connectors  paste, upload, URL, Google Drive, GitHub
packages/mcp         the MCP server and its authorization
packages/ui          the accessible component set
packages/config      typed configuration and product identity

Documentation

• Architecture — how the pieces fit and where data flows

• Threat model — what this protects against, and what it does not

• Privacy and data flow — every processor, every plaintext boundary

• Database — schema, tenancy, and migrations

• Connectors — sources and what each one reads

• Connecting an AI tool — Claude Code, Codex, and the remote endpoint

• Backup and recovery — losing your computer, and getting back

• Deployment — Supabase, Vercel, Railway, WorkOS

• Environment variables — every setting, with safe placeholders

• Cost controls — what costs money and how it is capped

• Troubleshooting

• Demo mode — exactly what is real and what is not without credentials

• Implementation status — what is done, what is not

Honest limits

• This is not end-to-end encrypted. While the application is working on your memory it can read it; that is what lets it search and answer.

• No SOC 2, GDPR compliance, or zero-retention claim is made or implied.

• Google Drive and GitHub are implemented but need credentials; without them they report "setup required" and use sample documents.

• The remote MCP endpoint's OAuth path is implemented but has not been exercised against a live issuer.

Project memory

This repository also carries the unified project memory the product was built from, under memory/. AGENTS.md and CLAUDE.md tell Codex and Claude Code how to read and update it.