121 lines
4.6 KiB
Markdown
121 lines
4.6 KiB
Markdown
# ClaudeMailbox
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A standalone MCP mail server that lets parallel Claude sessions coordinate with each other. Any Claude session (plain terminal, ClaudeDo worktree, anything that consumes `.mcp.json`) can send messages to a peer session's inbox, check for pending messages, and discover other active mailboxes.
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Not a substitute for `run_in_background: true` — that handles single-session responsiveness. This handles **session-to-session** coordination.
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## Architecture
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One long-running daemon binds HTTP on loopback, hosts the MCP server at `/mcp` and a small REST API at `/v1/*`, and persists state in a single SQLite file. Sessions declare themselves via an `X-Mailbox` header in their `.mcp.json`.
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```
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session-backend session-frontend external sender
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(X-Mailbox: backend) (X-Mailbox: frontend) (CLI / UI / hook)
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| | |
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| HTTP | |
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+--------------+-----------------+--------------------------+
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v
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claude-mailbox serve (ASP.NET Core + Kestrel)
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/mcp MCP tools
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/v1/* REST for non-MCP senders
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/health
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v
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~/.claude-mailbox/mailbox.db (SQLite WAL)
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```
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## Install
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```powershell
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dotnet publish -c Release -r win-x64 --self-contained -p:PublishSingleFile=true
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```
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Put the resulting `claude-mailbox.exe` on your `PATH`.
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## Daemon lifecycle
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The daemon is a normal console process. Pick whichever level of automation you want:
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1. **Manual.** Open a terminal, run `claude-mailbox serve`, leave it open. Stops when you close the window.
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2. **Startup shortcut.** Drop a shortcut to `claude-mailbox serve` in `shell:startup` — starts on login.
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3. **Windows Service.** `sc.exe create ClaudeMailbox binPath= "C:\path\to\claude-mailbox.exe serve" start= auto` — same pattern ClaudeDo uses.
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Defaults: port `47822`, bind `127.0.0.1`, database at `%USERPROFILE%\.claude-mailbox\mailbox.db`. All overridable:
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```
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claude-mailbox serve [--port 47822] [--bind 127.0.0.1] [--db-path <path>]
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```
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## Use from a Claude session
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Drop this into your project's `.mcp.json` (one per session, different `X-Mailbox` values):
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```json
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{
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"mcpServers": {
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"mailbox": {
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"type": "http",
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"url": "http://127.0.0.1:47822/mcp",
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"headers": {
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"X-Mailbox": "backend"
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}
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}
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}
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}
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```
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Four MCP tools are exposed:
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| Tool | Purpose |
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| `mcp__mailbox__send(to, body)` | Send a message to another mailbox |
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| `mcp__mailbox__check_inbox()` | Pull all pending messages for this mailbox (marks delivered) |
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| `mcp__mailbox__peek_inbox()` | Non-consuming check — returns `{ pending, oldestAt }` |
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| `mcp__mailbox__list_mailboxes()` | Discover known mailboxes and who has mail for you |
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### Suggested CLAUDE.md snippet for poll discipline
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```
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When coordinating with a peer session, call mcp__mailbox__peek_inbox
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after each subagent completes. If pending > 0, call mcp__mailbox__check_inbox
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and treat the messages as input with priority over the current plan.
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```
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## CLI client mode
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Any external process (scripts, UIs, hooks) can talk to a running daemon without needing MCP:
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```
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claude-mailbox send --to <mailbox> --from <mailbox> --body <text> [--url http://127.0.0.1:47822]
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claude-mailbox peek --name <mailbox> [--url ...]
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claude-mailbox check --name <mailbox> [--url ...]
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claude-mailbox list [--url ...]
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```
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The CLI subcommands are thin HTTP clients against the `/v1/*` endpoints.
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## REST surface
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| Method | Path | Requires `X-Mailbox` | Purpose |
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|---|---|---|---|
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| `GET` | `/health` | no | `{ status, version, dbPath }` |
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| `POST` | `/v1/send` | yes (sender) | `{ to, body }` |
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| `GET` | `/v1/peek?name=<mailbox>` | no | read-only status |
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| `POST` | `/v1/check-inbox?name=<mailbox>` | yes (must match `name`) | consume inbox |
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| `GET` | `/v1/list` | no | list all mailboxes |
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## Development
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```
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dotnet build
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dotnet test tests/ClaudeMailbox.Tests/ClaudeMailbox.Tests.csproj
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dotnet run --project src/ClaudeMailbox -- serve
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```
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Test suite covers end-to-end coordination, concurrent `check_inbox` race safety, and schema idempotency.
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## Scope
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- Loopback bind only (v1). Cross-machine coordination is a future extension — swap the middleware for token auth and change the bind address.
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- No auth on loopback. Local filesystem permissions are the trust boundary.
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- No message expiry or cleanup. Delivered messages stay as a timeline/audit log.
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