V2 release soon Open sourcemacOS
Persistent memory for CLI agents.
GreyMatter turns every session into linked Markdown notes, versioned with git, that your agent finds again from one session to the next. Built on and for Claude Code, and it also works in other agents' environments, on demand.
Stack
- Python
- Bash
- Electron
- WebGL
- GitHub Actions
- Apache 2.0
- 46 releases
- published under the Apache 2.0 licence, on a public repository.
- < 50 ms
- per search across a thousand notes.
- 100% local
- no account, no server: files on your machine.
- 21 markers
- checked for leaks before every release. A single hit blocks it.
Interfaces
Two views on your memory.
Everything else is Markdown: you read it, edit it and version it like code.
Launch
The map rebuilds from your files.
The logo assembles while the notes load. The map is recomputed on every launch, so it always reflects the actual state of the repository.
Menu bar
Watch your agents work, live.
V2 · soon
Each step of the task shows up under the pill, colour-coded by type of work, until “Done”. At idle it uses 4% of one CPU core.
Features
Stop re-explaining things to your agent.
Claude Code starts from zero every session. GreyMatter keeps what was learned and makes it available across all your projects.
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Distillation
At the end of a session, the transcript is split into notes: one fact per note, with its source and confidence level.
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Search on demand
A keyword, a sentence or brain recall: the relevant notes land in context. Nothing gets in unless you asked for it.
Released (1.28): automaticV2, soon: on request
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Notes linked across projects
A lesson learned on one project is available in every other. The bigger the repository, the sharper the answers.
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8 maintenance agents
Distil, file, challenge, link, archive, repair, watch the machine, synthesise. Each agent can only write to its own zone.
Released (1.28): 8 agentsV2, soon: in 4 ships
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Freshness review
A note that was never re-checked enters a review queue, dated from the git history.
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Updates with rollback
The engine replaces itself on every session, and brain update --rollback returns to the previous version. Your notes are never modified.
Architecture
Built on Claude Code hooks.
No account, no remote service: every step fires on a session event.
- 01 The repository Markdown files versioned with git: notes, map, state.
- 02 On demand A lexical search selects the relevant notes and injects them into the conversation.
- 03 During the session Every file read or written is logged.
- 04 Session end The transcript is archived, distilled into notes, then filed. A maintenance agent only starts if its sensor crosses a threshold, one per pass.
Product decisions
Two features, revisited after measuring.
If a feature isn't used, it goes, even when it was the original idea.
Automatic injection
Before
4%
of the notes injected unasked were actually opened: 139 out of 3,256, over 30 days.
After
On demand
Notes still arrive, when asked for: with them, the agent got 10 out of 10 test questions right. One setting restores automatic sending.
Pill at idle
Before
28% + 29%
of one CPU core: the pill, then the macOS process that draws the screen. Every frame was paid for twice.
After
4% + 20%
Each area animates at the rate of what actually moves, and nothing renders while the window is hidden.
Install in two commands.
GreyMatter installs as a Claude Code plugin, then updates itself every session.
/plugin marketplace add Yuno15-bb/GreyMatter-engine
/plugin install c-brain@c-brainEvery release goes through CI: install, uninstall and a replay of every migration, twice, with zero lost notes required. Public version: 1.28. The pill, the 4 ships and search on demand ship in the next one.
- Role
- Design, architecture, extraction, publication
- Context
- Personal project · open source · 2026
- Result
- 46 releases published under Apache 2.0, installable in one command — and a leak check that is allowed to block any publication.