Brainiac

A local second brain for any LLM. Your notes stay plain Markdown and YAML on your own disk. The brain command-line engine gives Claude Code, Codex, Gemini CLI and Claude Desktop fast, sourced search over them. No vendor lock-in, no cloud index, no server.

Why

Most retrieval tools ask you to trust one app and its plugin pipeline forever. Brainiac keeps the substrate as files (vault/brain/ and vault/raw/), keeps the search index as a cache you can rebuild at any time, and passes every read through a deny-by-default classification filter before a model sees it. You decide what an LLM may see, note by note.

Install

Brainiac is one engine install plus one setup command. The setup command, brain init --full --apply, creates your vault, seeds three sample notes, builds the search index, provisions the audit signing key and registers the maintenance task. Pick the path that matches how you work.

1. Let your AI assistant do it. Paste this into any assistant that can run commands on your machine (Claude Code, Codex, Gemini CLI):

Install Brainiac for me. Fetch and follow this exactly, asking me only what it says to:
https://raw.githubusercontent.com/Autopsias/brainiac/main/docs/install/LLM-INSTALL.md

2. Claude Code plugin. One command installs the plugin, and the plugin installs the engine:

/plugin install brainiac-manager --marketplace Autopsias/brainiac
/brainiac-install ~/brain

The one-command form needs Claude Code 2.1.275 or later. On an older version, run /plugin marketplace add Autopsias/brainiac, then /plugin install brainiac-manager@brainiac. In Claude Desktop, add the marketplace under Customize › Plugins.

3. By hand, on any OS. With uv, pipx or pip already present:

uv tool install 'brainiac-cli[mcp]'        # or: pipx install 'brainiac-cli[mcp]'
BRAIN_VAULT=~/brain/vault brain init --full --apply

Without Python, the bootstrap script fetches uv and installs through it. Run it, then the brain init line above:

# macOS / Linux
curl -fsSL https://raw.githubusercontent.com/Autopsias/brainiac/main/install.sh -o /tmp/brainiac-install.sh && bash /tmp/brainiac-install.sh

# Windows (PowerShell)
irm https://raw.githubusercontent.com/Autopsias/brainiac/main/install.ps1 -OutFile install.ps1; .\install.ps1
$env:BRAIN_VAULT = "$HOME\brain\vault"; brain init --full --apply

With Node.js 18 or later, npx brainiac-install --vault ~/brain does the engine install and the vault setup in one command. It needs uv, pipx or Python on the machine already.

Every platform, step by step: docs/install/README.md.

First search

brain search "welcome" --json

Three things to know on day one:

• Your notes live in the vault (~/brain/vault above). They are the source of truth. The index is a cache in your app-data folder. brain rebuild recreates it at any time.
• Semantic search downloads its model (bge-m3-int8, about 563 MB) once, on first use. brain warmup fetches it up front.
• An existing folder of notes is not indexed by brain init. Run brain rebuild once, or the first search returns nothing.

brain --help lists every command.

On a Codex-only macOS host, Sunday synthesis can use the opt-in Codex adapter. It handles new source-derived notes; the stock Claude runner remains the default.

Update

brain update            # --dry-run shows the plan; your notes are never touched

It detects how you installed the engine (uv, pipx, pip or an editable checkout), upgrades it, refreshes the Claude Code plugins, restages every registered Cowork workspace and verifies with brain doctor. In Claude Code, /brainiac-update runs the same thing.

You rarely need to run it. The hourly maintenance task applies a newer version on its own, and keeps it only when brain doctor is green and a real query embed succeeds. brain doctor on its own is a read-only health check with the exact fix for anything stale.

A second vault

The install is per machine. Vaults are per project. Point the same brain at another folder and it gets its own index and audit chain:

export BRAIN_VAULT=~/vaults/my-new-project
brain init --full --apply
brain rebuild            # only when the folder already holds notes

Details, including the per-vault overlay and the scheduled task: docs/install/second-vault.md.

How the AI assistants are wired

Every assistant calls the brain CLI through its normal shell. No MCP server is required. brain connect --client <name> wires one client (claude-code, claude-desktop, codex or gemini), shows the diff and asks before it touches a config file. AGENTS.md is the conventions file every assistant reads; CLAUDE.md imports its short core.

The one exception is the Claude Desktop Chat tab, which cannot run a command. For that surface, install the brainiac.mcpb extension from the latest release, or run brain connect --client claude-desktop. Pick one. The full matrix is in docs/harness-wiring.md.

Security, in one paragraph

All data stays on the local disk: notes are Markdown, the index is a local SQLite file, and the project holds no model API keys. Every read command filters notes by their classification tier before it prints, and an unlabelled note counts as the most restrictive tier. Every committed write is Ed25519-signed and hash-chained, with the key in the OS secret store. A sandboxed surface such as Cowork gets a read-only snapshot and a draft inbox, and can never sign or index. Runtime dependencies are pinned in requirements.lock; CI runs pip-audit weekly and emits an SBOM.

• Controls, threat model and residual risks: docs/security-overview.html
• Classification tiers: docs/classification-scheme.md
• Reporting a vulnerability and rotating the audit key: SECURITY.md

Where to go next

• Every document, grouped by purpose: docs/README.md
• What runs where, and why Cowork needs a host: docs/install/new-owner.md
• The conventions every assistant reads: AGENTS.md
• The words used in these docs: docs/glossary.md
• Contributing: CONTRIBUTING.md (this repository is a release mirror; read that file first)
• Changes by version: CHANGELOG.md

Repository layout

AGENTS.md            conventions and the note schema
src/brain/           the brain CLI and engine (index, search, audit)
plugins/             the three Claude Code plugins (kernel, extras, manager)
docs/                install guides, specs, security notes, decision records
tools/validate.py    conventions validator for a vault
vault/               the small sample vault used above

License

Apache-2.0. Built clean-room; see docs/clean-room-log.md.