ContextLib MCP server

ContextLib

A project library that outlives every agent session.

Real screenshot of the sample library (an invented project).

A ctxlib session: an owner's decision lands current, an agent's lesson waits in the inbox, a secret is refused, and doctor passes.

Each project's knowledge — decisions, requirements, facts, lessons, glossary, sources and returned work — is stored as plain Markdown files with a small front-matter block, in one folder per project. The folders can sit on an external SSD. A person can understand a project from Finder alone. Agents read and write the same files through a CLI (ctxlib) and an MCP server (context_* tools). Any database is a search index rebuilt from the files, never the source of truth.

It is the open core of the context plugin of AgentBrain.

The Python package is agentbrain_contextlib. The CLI is ctxlib. Python 3.9+, standard library only. Git is optional.

Why

Agent sessions end. Chat logs drift. A store that only a model can parse is a dead end the first time you open Finder on an airplane.

ContextLib keeps the durable layer as files you can read, diff, copy, and take to another Mac. The search index is disposable. The Markdown is the product.

60-second quickstart

pip install "git+https://github.com/willykeenan/agentbrain-contextlib"

ctxlib init ~/ContextLib --project lighthouse-app \
  --name "Lighthouse App" \
  --purpose "Harbor dashboard for lamp status, fog signals, and traffic"

ctxlib add lighthouse-app decision "Use keeper logs as lamp status" \
  --body "**Decision:** Lamp status comes from keeper logs, not AIS." \
  --author mara \
  --tag lamp --tag keeper-log

ctxlib brief lighthouse-app
ctxlib doctor lighthouse-app --ten-minute

The library path is --library PATH, else env CONTEXTLIB_ROOT, else ~/ContextLib.

A finished sample you can open in Finder without installing anything lives at examples/sample-library/. Start at that README, then the project BRIEF, then decisions/INDEX.md.

Full walkthrough: docs/QUICKSTART.md.

CLI (ctxlib)

ctxlib [--library PATH] COMMAND

Shortened. The full README is on GitHub.