Koushi (光子・格子)
Why Koushi?
- All your accounts, one window. Each Matrix account gets its own tab and
stays signed in and syncing, with its own unread count.
- Multilingual by design. IME-safe typing, and search that handles Japanese,
Chinese, and Korean text. The interface is available in English, Japanese,
Simplified Chinese, Traditional Chinese, and Korean.
- Find the conversation again. Local full-text search, including encrypted
rooms.
- Notifications even when your server sends none. Koushi can email you
(Resend or SMTP) or notify WeChat (ServerChan) from your own computer.
- Works with your AI assistant. Koushi can act as a local MCP server, so
Claude Code, Codex, and other MCP clients can search, summarize, and reply to
your chats through the running app, only for the accounts you allow.
- Desktop first. Three-pane layout, threads, Markdown, code, math, keyboard
shortcuts, system tray, and native notifications.
The website has screenshots and the
full list. Koushi uses the Matrix protocol through the
Matrix Rust SDK, with a Rust core and a Tauri desktop shell. Voice and video
calls, screen sharing, bots, and widgets are not included yet.
Use Koushi from your AI assistant
Koushi can act as a local Model Context Protocol
server. Your assistant talks to the Koushi app already open on your computer,
so it never holds your encryption keys. Then just ask:
Which rooms have unread messages? Summarize the Design room.
Find the invoice someone sent me last month.
Reply to that message saying I will send the file tomorrow.
- Read: list rooms with unread counts and mentions, read recent messages,
and search history, including encrypted rooms.
- Act: send messages and replies, download attachments, and wait for new
activity.
- You decide: until you grant access, an assistant sees only account ids.
Reading, sending, and attachments are separate permissions, per assistant and
per account.
claude mcp add --scope user koushi -- /path/to/koushi-mcp --client-name claude-code
The koushi-mcp launcher ships with Koushi, and App Settings → AI
assistants shows its path ready to copy. The first time an assistant asks for
something, Koushi shows an approval dialog; you can change or remove access
later on the same settings page. See Connect an AI assistant for Claude
Code, Codex, other MCP clients, and URL-only connectors.
Downloads
Platform Support
- macOS (Apple Silicon): officially supported. Releases are Developer ID
signed, notarized, stapled, and checked by Gatekeeper.
- Windows and Linux: built by CI but untested. The maintainer has no
Windows hardware; only an Ubuntu 24.04 WSL2 build has been launched.
Testers and maintainers for these platforms are very welcome.
Help
Read the user guide, or ask ChatGPT or another AI
assistant in your own language. Include the repository URL, your Koushi
version, and your operating system, for example:
I use Koushi version [version] on [operating system]. Please consult
https://github.com/shinaoka/koushi-matrix, read the user guide for my release
tag, and explain how to search past messages. Link to the sources you used.
llms.txt indexes the same help for AI readers. See
version selection for an
installed release.
Contributing
Issues and pull requests are welcome, especially from Windows and Linux users.
To build from source, see Develop Koushi.
The name
Koushi (コウシ) is a Japanese double pun: 光子 (photon: light, signal)
and 格子 (lattice: a grid, a nod to Matrix). The logo is a photon resting on
a lattice.
License
MIT OR Apache-2.0, at your option (LICENSE-MIT,
LICENSE-APACHE). Unless you explicitly state otherwise, any
contribution intentionally submitted for inclusion, as defined in the
Apache-2.0 license, is dual licensed as above without additional terms.
Third-party attributions are in THIRD_PARTY_NOTICES.md.
Terminal users can use the bundled read-only koushi CLI; see Command-line access.
