brain-core

A memory for your Claude Code agent that survives the session.

Install in one line

macOS and Linux

curl -fsSL https://raw.githubusercontent.com/xy-claude/brain-core/main/install.sh | bash -s -- --agent Atlas --user Alex --desktop

Windows (PowerShell)

& ([scriptblock]::Create((irm https://raw.githubusercontent.com/xy-claude/brain-core/main/install.ps1))) -Agent Atlas -User Alex -Desktop

Atlas is your agent's name, Alex is yours. When the installer finishes:

cd ~/Agents/Atlas
claude

Both lines install the same things: the agent, Hindsight (the vector store, about 2 GB), the daily and weekly jobs, Claude Code, and the connection to the Claude desktop app. No API key is needed.

Every step, every flag and the common problems: Install details.

What you get

• Sessions that start where the last one ended. Each one opens with yesterday's brief, your decisions, the facts that changed and the corrections you gave.
• Five tools, not thirty. One local MCP server the agent uses by itself.
• Files you can read. Memory is markdown in a folder on your disk, indexed by SQLite and, optionally, by Hindsight, a self-hosted vector memory.
• Nothing in someone's cloud. Nothing leaves your machine except the LLM calls you already make.
• An eval that proves recall. It runs in CI; the numbers are in Does it work?

It is for one person running one or more agents on their own computer. It is not a hosted service and not a team product.

The problem

Every session with a coding agent starts from zero. You explain the project again, the decision you made last week again, the thing it got wrong on Tuesday again. Memory add-ons exist, but they put your notes in someone's cloud, expose 30 tools the agent cannot choose between, and nobody shows you an eval.

brain-core is the opposite: local, five tools, markdown files you own, and a test suite that reports hit rates.

How it works

1. brain init scaffolds an agent folder. It writes a CLAUDE.md with the agent's name and yours, five rule files (identity, doctrine, authority, memory, system), three skills, a safety hook, an .mcp.json and an empty vault. Claude Code reads that folder as a project, so the agent knows how to use its memory from the first message.
2. brain serve runs as an MCP server inside Claude Code. It exposes exactly five tools. The agent calls them the way it calls any other tool; you never run them by hand.
3. Every session has a shape. The agent opens with brain_session('start'), which returns one block: today's brief, the executive state, the mental models, a recall per active mission, and a flag if the previous session crashed. It closes with brain_session('end'), which files the day's archive and rewrites state for tomorrow.
4. Memory is written, not inferred. When you say something worth keeping, the agent calls brain_remember(text, kind). The text goes to the vault first, then the SQLite index, then Hindsight, then the relations table, and the reply says what each layer did. A duplicate is skipped. A fact whose value changed gets a ⚠ Fact changed banner and the old line stays, so the history is visible.
5. Recall is one query across every store. brain_recall(query) searches the vault, the index and Hindsight at once, deduplicates, ranks by relevance and recency, and caps the reply at 6k tokens so it never floods the context.
6. Two cron jobs do the housekeeping. brain daily writes the next morning's brief and backs up Hindsight. brain weekly archives sessions older than 30 days into a monthly summary and refreshes the mental models.

flowchart LR
    CC[Claude Code] -->|MCP, 5 tools| B[brain serve]
    B --> V[(vault/ markdown)]
    B --> S[(brain.db SQLite + FTS)]
    B --> H[(Hindsight vector memory)]
    B --> G[(relations table)]
    CRON[brain daily / weekly] --> V
    CRON --> H

The five tools

Plus brain_status() for health in one call: which stores are up, how many tokens the always-loaded context costs, whether a session is open, and which decisions are waiting on you.

Is it an MCP server or a tool?

Both. One Python package, three ways in:

Install details

Before you start

Pick two names before you run the command: the agent's name (--agent), which becomes its folder and identity, and your own (--user), which is how the agent addresses you. Both can be changed later by editing CLAUDE.md.

macOS, one line

curl -fsSL https://raw.githubusercontent.com/xy-claude/brain-core/main/install.sh | bash -s -- --agent Atlas --user Alex --desktop

In a hurry, or no 2 GB to spare? Add --lite: vault plus SQLite full-text search, no Hindsight, installed in about a minute. Everything in the five tools works; what you give up is semantic recall over paraphrases, mental models and the weekly reflection. The recall numbers in Does it work? are measured on exactly this configuration. Upgrade any time with brain hindsight install, then uncomment the hindsight: block in brain.yaml.

curl -fsSL https://raw.githubusercontent.com/xy-claude/brain-core/main/install.sh | bash -s -- --agent Atlas --user Alex --desktop --lite

What it does, in order. Re-running skips what is already there, so after a failure you fix the cause and run the same line again.

== 1/8 Xcode command line tools      present
== 2/8 Homebrew                      present
== 3/8 uv, gh, gitleaks, node, Claude Code
== 4/8 brain-core (v0.4.0)           installed with uv tool
== 5/8 Agent Atlas at ~/Agents/Atlas  31 files written
== 6/8 Hindsight (required store)    service: healthy
== 7/8 Cron                          daily 06:07, weekly Sun 07:13
== 8/8 Doctor                        Health check: OK

After the installer

One thing the installer cannot do for you:

claude                                  # sign in to Claude Code once

Hindsight needs an LLM to reason over memories, and the installer picks one that works. With ANTHROPIC_API_KEY in your shell it uses that key. Without it, Hindsight uses your Claude Code login, and the installer says so; that mode is for personal use only. To move to a key later:

export ANTHROPIC_API_KEY=sk-ant-...     # add it to ~/.zshrc too
brain hindsight install                 # copies the key into ~/.config/hindsight/env (mode 600) and restarts the service

Already have an agent?

brain adopt ~/Agents/Atlas --vault ~/Agents/Atlas/vault --bank atlas-brain --user Alex

Adds brain.yaml, the brain MCP server, the four hooks and the memory rule to an existing Claude Code folder, then indexes its facts. CLAUDE.md, skills and the vault are left alone; omit --bank to run lite.

Linux

The same one line; --desktop is skipped, because the desktop app has no Linux build. It needs git and curl already present. It then installs uv from astral.sh, installs Claude Code with npm when node is present, runs Hindsight as a systemd --user service, and writes the two jobs into your user crontab as tagged lines it can find and replace on re-run.

Windows

One line in PowerShell (Windows PowerShell 5.1 or PowerShell 7), with the same flags as on macOS in PowerShell spelling: -Lite for --lite, -Desktop for --desktop. It works under the default Restricted execution policy; nothing has to be changed first.

& ([scriptblock]::Create((irm https://raw.githubusercontent.com/xy-claude/brain-core/main/install.ps1))) -Agent Atlas -User Alex -Desktop

Every step says what it is doing while it does it: downloads count their megabytes, longer steps print "still working" every 15 seconds, and nothing waits without a time limit.

The last lines are the verdict, one of two:

== Install complete: every step above finished
  memory folder     C:\Users\Alex\Agents\Atlas
  Hindsight         running (provider claude-code)
  desktop app       connected and loaded
  scheduled tasks   created
  Claude Code       installed

or == Install NOT complete: N step(s) did not work, followed by each step that failed, why, and the command to run it again. Running the whole line again is always safe: what is in place is kept, and brain is upgraded.

Add -Lite to skip Hindsight: vault plus SQLite full-text search, the same configuration the recall numbers below are measured on. The provider is chosen as on macOS (-Provider, -ApiKeyEnv). An agent made lite stays lite when the line is run again; it upgrades with brain hindsight install, then uncomment the hindsight: block in brain.yaml. Other options: -Dir, -ProfileDir, -Ref. Open a new terminal afterwards so brain is on PATH.

Claude desktop app

The agent's memory also works in the Claude desktop app's chat, on macOS and Windows. The install lines above carry --desktop (macOS) and -Desktop (Windows) for this. To connect an agent you already have:

brain desktop ~/Agents/Atlas

It adds one brain server to the app's claude_desktop_config.json, keeps everything else in that file, and leaves a .bak copy the first time it changes one. Then quit the app fully and reopen it; closing the window is not enough. On Windows the installer watches for that restart and tells you whether the app has loaded brain-core. On Windows a Microsoft Store install keeps its settings in a package folder, and that one is written too when it exists. If the file is somewhere else, open it from the app (Settings, Developer, Edit Config) and pass it with --config.

The desktop app has a memory of its own, kept on Anthropic's servers. The two do not conflict, but a fact can end up in both. For one source of truth, work in a desktop project with "Use account memory" turned off and tell it in the project instructions to use brain_recall and brain_remember.

Manual, any platform

uv tool install --python 3.12 brain-core-mcp   # Python 3.12 to 3.14; or: uv tool install git+https://github.com/xy-claude/brain-core@v0.4.0
brain init Atlas --path ~/Agents/Atlas --user Alex
brain hindsight install          # launchd, systemd --user, or a logon entry on Windows
brain cron install ~/Agents/Atlas    # launchd, crontab or Task Scheduler
brain desktop ~/Agents/Atlas         # optional: the Claude desktop app, macOS and Windows
brain doctor ~/Agents/Atlas

Updating

Nothing updates by itself: the copy you installed stays as it is until you change it. brain-core tells you when there is something newer. brain daily asks PyPI once a day, and when a newer version exists the daily brief and brain doctor say so in one line:

update     brain-core 0.4.25 is available (this is 0.4.23). Update: `uv tool upgrade --no-cache brain-core-mcp`, then restart Claude.

Run that command, or paste the install line again; both keep your agent folder as it is. Restart Claude Code or the Claude desktop app afterwards, since a running one keeps the copy it started with. The daily request sends nothing about you or your memory; it only reads the version number. To stop it, set update_check: false under cron: in brain.yaml.

An update replaces the program, not the files in your agent folder. When a release changes a rule, a hook or a setting in the template, the changelog says what to copy.

Check it worked

brain doctor ~/Agents/Atlas

It prints the agent name, the config path, row counts per table, and Health check: OK. Store health shows up in the first brain_session('start') reply and in brain_status(). The common problems:

First session

cd ~/Agents/Atlas && claude

The agent's CLAUDE.md tells it to open with brain_session('start'). What comes back:

{
  "session_id": "s-20261102-a1b2c3",
  "brief": "# Daily Brief — 2026-11-02 ...",
  "executive_state": "## Primary Objective ... ## Top Missions ... ## Pending Decisions ...",
  "mental_models": {"active-priorities": "..."},
  "missions": {"M-001 first mission": [ ...3 recall hits... ]},
  "inbox": 0,
  "recovery": null
}

On day one the brief is empty and the executive state is the template. That is expected. Spend the first session telling the agent what you are working on: the project, the stack, the decisions already made, how you like to work. Each statement that matters becomes a brain_remember call, and the reply shows what every layer did:

{"status": "written", "layers": {"vault": {"status": "written", "detail": "facts.md › System"},
                                 "sqlite": {"status": "written"},
                                 "hindsight": {"status": "written", "detail": "op 162bdbaa"}}}

Things to try in that first session:

• State a fact, then change it. "The API listens on 8887." Later: "Correction, it is 8888." The second write returns a ⚠ Fact changed banner and vault/facts.md keeps both lines.
• Give it a source. Paste a URL or a GitHub repo and ask it to distill it. The page lands in vault/raw/ untouched, and the agent compiles a page in vault/knowledge/.
• Ask about something from earlier. "What did we decide about the database?" is one brain_recall call, and each hit names the file it came from.
• Open the vault in your editor. Every write you just saw is a line in a markdown file. Edit it if the agent got it wrong.

Say "thanks, we're done" and it runs brain_session('end'). Tomorrow at 06:07 brain daily writes the next brief from what you did today, and the next claude session opens with it.

What is in the agent folder

~/Agents/Atlas
├── CLAUDE.md                 identity and the five-tool protocol (3k tokens always loaded)
├── .claude/
│   ├── rules/                01-identity 02-doctrine 03-authority 04-memory 05-system
│   ├── skills/               distill, session-end, brain-check
│   └── hooks/                block-dangerous-bash.sh (rm -rf, force-push, curl|sh …)
│                             + recall of past sessions when a command fails
├── .mcp.json                 brain serve . + Hindsight
├── brain.yaml                stores, session files, cron schedule
├── vault/                    facts.md patterns.md decisions_log.md corrections.md
│   ├── sessions/             one file per day (HSAM)
│   ├── knowledge/ raw/       the LLM-wiki: immutable sources, compiled pages
│   └── executive_state.md    objective, missions, pending decisions
└── data/brain.db             SQLite + FTS5 + relations + transcript index

Everything is markdown or SQLite. Open the vault in Obsidian, grep it, commit it, delete a line. The agent will not mind.

Does it work?

The eval is part of the test suite and runs in CI.

The slices are the ones the memory benchmarks (LoCoMo, LongMemEval) say a single hit-rate hides: a changed value must outrank the stale one, an unanswerable question must return nothing, a question about a day must surface that day's archive. Recall takes about 1.7 s per query with Hindsight; a full start block is about 4 s and under 6k tokens.

python tests/eval/run_recall.py --config ~/Agents/Atlas/brain.yaml   # your own vault

Twelve traits, innate and grown

A brain-core agent is born with twelve traits and grows them with experience. Innate is what brain init ships and what survives a cold start with the vault wiped; grown is what accumulates in the vault. brain_status() scores each from evidence on disk, and brain daily logs one line a day so the curve shows over weeks.

A trait never gets one number. It gets signals, each with a sample size and a verdict: defensible when the answer key comes from a file the agent did not write that session, cost when it is a size or an age, pending when the evidence does not exist yet. Artefact counts and self-written scores are not signals. The list and the research behind it: docs/TRAITS.md.

How memory is organised

Rules: idempotent by content hash, append-only, nothing deleted, secrets refused before any store sees them. Details in docs/VAULT_SCHEMA.md.

Requirements

• macOS, Linux with systemd, or Windows 10 1809+ for the installer; the library and MCP run anywhere Python 3.12 does
• optional: Hindsight (MIT) as the vector store, installed for you unless --lite (-Lite on Windows). Postgres is embedded; embeddings run on CPU
• with Hindsight: an LLM key for its reasoning, or a Claude Code login for personal use

On PyPI the package is brain-core-mcp (the plain name collides with an unrelated project); the command is still brain and the import is still brain_core.

Roadmap

• an import for existing notes folders
• a recall-miss log that grows the eval set from real misses

How it compares to claude-mem, mem0 OpenMemory and a plain CLAUDE.md: docs/COMPARISON.md. Shipped milestones: docs/MILESTONES.md. Design: docs/SPEC_v0.2.md. Threat model for a memory that reads untrusted text: docs/THREAT_MODEL.md.

Contributing

Issues and pull requests welcome. uv sync --all-extras --all-groups, then ruff check, mypy, pytest. See CONTRIBUTING.md.

License

MIT.