Control your coding agents (Claude Code, Codex, Cursor, Grok, Hermes, Pi) locally by default, with optional multi-device sync.
Every device runs a small engine that stores sessions on that device. A new installation starts in local-only mode without an account or a network connection.
Postillion is built on zeronsh/comet, rebuilt on GPUI. main starts from a single squashed import of upstream — the unsquashed history is upstream's own, at zeronsh/comet. The pre-GPUI Tauri version is on the v1-tauri branch and tag.
There is no hosted installer. Build from source or take a build from Releases.
cargo build --release -p postillion
./target/release/postillion statusDay-to-day:
postillion status # local/synced mode and engine status
postillion daemon start|stop|restart|statusOn macOS: build postillion from source and run postillion daemon install to install the launchd service.
On Windows: download the release zip and run Install.ps1 (per-user, no admin rights). It installs into %LOCALAPPDATA%\Programs\Postillion, adds a Start Menu shortcut, and puts the directory on your user PATH. There is no background service on Windows — the desktop app runs the engine in-process, and postillion update reports new versions rather than applying them, so update by re-running Install.ps1 from the newer zip.
Postillion ships no hosted sync endpoint. A bare install is local-only and stays that way until you point it at a server you run yourself:
deploy/ has everything needed to run postillion-server on your own machine, via Coolify or systemd.
postillion-server currently authenticates with a single shared token, so point the client at the same value the server runs with:
export POSTILLION_EDGE_URL=https://sync.your-domain.example
export POSTILLION_EDGE_TOKEN=<the server's POSTILLION_SERVER_TOKEN>Generate it with openssl rand -hex 32. Avoid base64 here: the token doubles as the client's user id, which becomes a path segment under the data directory, and base64's / would split it.
Anyone holding that token can read every chat on the server. Chats are stored so the server can read them — there is no end-to-end encryption, by decision, not by omission: the web panel exists to continue a chat from the browser, and encrypting content would mean putting the key in the browser to show it. Anyone you open registration to needs to know the operator can read their chats, and a database backup is a plain copy of them. See deploy/README.md for the rest of the limits. Multi-user sign-in over WorkOS AuthKit (POSTILLION_WORKOS_CLIENT_ID) targets the upstream Cloudflare edge, not postillion-server.
Once an endpoint is configured, sign in only when you want to open your account's synced workspace. Authentication changes the profile selected by the next engine start, so stop the daemon before changing it:
postillion daemon stop
postillion login
postillion daemon startYou can then start an agent on one synced device and follow or drive it from another. An always-on machine such as a VPS can keep those agents working after you close your laptop.
Signing in does not upload, move, or import existing local sessions. Local sessions and their attachments remain under the local profile and reappear when you return to local-only mode:
postillion daemon stop
postillion logout
postillion daemon startpostillion login and postillion logout refuse to modify credentials while an engine owns the data directory. The desktop app follows the same next-restart profile boundary.
| Linux | macOS | Windows | |
|---|---|---|---|
| Desktop app | yes | yes | builds and runs; GPU path not yet verified on real hardware |
| Background service | systemd | launchd | none — engine runs in-process |
| Self-update | yes | yes | reports only |
See docs/PARITY.md for the per-platform gaps.
Developing or curious how it works? See ARCHITECTURE.md.
Licensed under the MIT License. Portions copyright the upstream Comet authors.