# claude-mailbox plugin

Lets Claude Code pull unread messages from a local `claude-mailbox` daemon before every prompt and inject them into the conversation context. Each Claude session gets a **unique mailbox identity** auto-derived from its session id, so two sessions in the same project never collide.

## Setup (three prompts, all inside Claude Code)

```
/plugin marketplace add https://git.kuns.dev/releases/ClaudeMailbox
/plugin install claude-mailbox@claude-mailbox
/claude-mailbox:mailbox-doctor
```

The doctor walks the rest:

1. installs the `claude-mailbox` binary via `npm install -g @kuns/claude-mailbox` if missing (asks first)
2. registers the daemon for autostart and starts it if needed
3. health-probes `http://127.0.0.1:47822/health`
4. optionally lets you set a **base prefix** (e.g., `backend`) — without one, mailbox names are anonymous (`claude-XXXXXXXX`)
5. runs a self → self smoke test

Restart Claude Code only if step 4 wrote a new prefix. After that, every prompt auto-pulls unread messages.

## Mailbox identity (the important bit)

Each Claude Code session gets its own mailbox name, derived from the session's UUID:

| Configuration | Resulting mailbox name |
|---|---|
| No `CLAUDE_MAILBOX_NAME` set | `claude-a8b3c1d2` (first 8 hex chars of session_id) |
| `CLAUDE_MAILBOX_NAME=backend` in `.claude/settings.json` env | `backend-a8b3c1d2` |

So if you open two Claude Code sessions in the same project, they'll be e.g. `backend-a8b3c1d2` and `backend-d4e5f6a7` — distinct, addressable, no manual setup.

The `SessionStart` hook announces the current session's mailbox name in the conversation context on startup. Peers discover each other via `claude-mailbox list` or the `mcp__mailbox__list_mailboxes` MCP tool.

## What the hooks do

| Hook | Command | Effect |
|---|---|---|
| `SessionStart` | `claude-mailbox session-announce` | Tells Claude its mailbox name for this session and instructs it on the `from` / `name` args to pass to MCP tools. |
| `UserPromptSubmit` | `claude-mailbox check --hook` | Pulls unread messages for the session's mailbox and injects them as context. Silent on empty inbox; emits a one-line setup hint when the daemon is unreachable. |

Cost: one local HTTP round-trip per prompt + Node coldstart (~100ms on Windows).

## MCP tools

The plugin also ships a `.mcp.json` so Claude has direct access to the mailbox via tool calls. Because the X-Mailbox header would be the same for two parallel sessions sharing one `.mcp.json`, **each MCP tool takes the caller's mailbox name as an explicit argument** (from the SessionStart announcement):

| Tool | Required args | Purpose |
|---|---|---|
| `mcp__mailbox__send` | `from`, `to`, `body` | Send a message to another mailbox. |
| `mcp__mailbox__check_inbox` | `name` | Pull all undelivered messages for your mailbox (marks delivered). |
| `mcp__mailbox__peek_inbox` | `name` | Non-consuming count of pending messages. |
| `mcp__mailbox__list_mailboxes` | `name` | Discover known mailboxes and `pendingForYou` counts. |

The SessionStart announcement spells out the exact args to pass, so Claude picks them up automatically.

## Slash commands

| Command | What it does |
|---|---|
| `/claude-mailbox:mailbox-doctor` | Diagnose + auto-fix the full setup. |
| `/claude-mailbox:mailbox-status` | Read-only health check. No changes. |
| `/claude-mailbox:mailbox-update` | Update the daemon to the latest npm version and restart it. |

## Coordinating two Claude Code sessions

1. Open two Claude Code sessions in the same (or different) project.
2. Each session's SessionStart hook announces its mailbox name in context.
3. In session A you can say: *"I have a second session running. Use `mcp__mailbox__list_mailboxes` to find it and send `<msg>`."* Claude will discover the peer's mailbox and send via `mcp__mailbox__send`.
4. Session B's `UserPromptSubmit` hook pulls the message on its next prompt and injects it as context.

You can also send from any shell:

```sh
claude-mailbox list
claude-mailbox send --from probe --to backend-a8b3c1d2 --body "hi"
```

## Uninstall

```
/plugin uninstall claude-mailbox@claude-mailbox
npm uninstall -g @kuns/claude-mailbox
claude-mailbox uninstall-autostart    # if you registered it
```