Title: Using jj as a file-based message bus for AI agents (jj-mailbox)

[MiaoDX]

Note, writen by opus and tweaked by myself.

I've been running multiple OpenClaw instances on different servers and needed them to communicate.

Why not multi agents in one claw instance? Because it's much fine to play with!!

Tried Slack bot-to-bot, looked at message queues — all felt too heavy for what's essentially "Agent A needs to tell Agent B something."

Note, slack is actually not bad, you can try it directly for bot2bot messages, much better than tg/discord/lark(feishu) etc for bots communications.

Then I realized: jj's unique properties make it a natural fit for this problem.

The idea: each agent has an inbox directory. To send a message, write a JSON file to the recipient's inbox. jj handles sync via git remotes. That's it.

Why jj instead of plain git:

• Concurrent safety — multiple agents pushing simultaneously won't corrupt the repo
• First-class conflicts — if two agents write at the same time, both messages are preserved (git would reject the push)
• Operation log — complete audit trail of every agent interaction, for free
• Working copy as commit — file writes are automatically captured, no explicit git add needed
• rsync/Dropbox safe — jj repos survive naive file sync, git repos don't

The protocol is intentionally minimal — inspired by Maildir (1995) and Plan 9's "everything is a file" philosophy:

mailbox-repo/
├── agents/{name}/profile.json    # who is this agent?
├── inbox/{name}/new/*.json       # unread messages
├── inbox/{name}/processed/       # read messages (history)
└── shared/                       # shared workspace

I built a CLI tool and have it running in production with two OpenClaw instances communicating across servers. There's a side-by-side comparison with the same conversation happening over Slack vs jj-mailbox in the README.

Repo: https://github.com/MiaoDX/jj-mailbox

Curious if anyone else has explored non-VCS use cases for jj.

The concurrent safety + operation log + conflict handling feels like it could power a lot more than just code versioning.

Say, all talks are auto logged, and this can be one interesting direction.

Thanks for reading~

[MiaoDX]

Showcase in feishu w/o native bot2bot support:

Discussions welcomed!!