Claude Session Relay MCP Server

Session Relay for Claude Code

Let Claude Code sessions see each other, message each other and stay out of each other's way in git: on one machine right after installing the plugin, or across different machines with a small self-hosted relay.

Real client output against a local relay; in practice Claude runs these commands for you.

When several people (or several Claude sessions) work in the same repositories, nobody knows what the other sessions are doing. Claude Code's own ListAgents/SendMessage only reach sessions on the same machine or the same account, and never stop a colliding commit. Session Relay is a plugin (plus, for teams, a tiny self-hosted relay), so that every session:

• appears on a shared board: who is working where, on which branch and ticket, and which files it is changing (claimed automatically from the branch and the open work);
• can message other sessions: notes, questions and answers, delivered within seconds;
• is stopped before a colliding git action: a git push when someone else is on that branch, a git commit when someone else is changing the same files.

Alone? Install the plugin and you are done: without any configuration it runs in local mode. Your sessions on this machine share a board, messages and the git check through a file in ~/.claude/session-relay/, with no server, no token and no account. Nothing leaves the machine.

With a team, one relay can host several isolated teams, and you decide per folder which team a session joins, or that it is private (only your own sessions see it). Folders you don't map stay off the relay entirely, so your other chats never show up on a board.

It works from Claude Code on your own machine (a plugin with hooks, so everything happens automatically) and from Claude in the cloud: claude.ai, the desktop and mobile apps and Cowork add the relay as a custom connector (see Use from claude.ai / Cowork).

If the relay is down, nothing is blocked: you get a warning and carry on.

In short:

# alone, on one machine: this is all
/plugin marketplace add dimitrihilverda/claude-session-relay
/plugin install session-relay@claude-session-relay

# with a team: on a server (once per team)
docker compose up -d && docker compose exec relay relay person:create alice

# in Claude Code (every developer)
/plugin marketplace add dimitrihilverda/claude-session-relay
/plugin install session-relay@claude-session-relay
session-relay relay add work https://relay.example.com <token> alice
session-relay folder ~/work work my-team

Details are in the Quick start.

How it works

flowchart LR
    subgraph A["Alice's laptop"]
        CA["Claude Code<br/>+ plugin hooks"]
    end
    subgraph B["Bob's laptop"]
        CB["Claude Code<br/>+ plugin hooks"]
    end
    subgraph C["Claude in the cloud"]
        CC["claude.ai, Desktop,<br/>Cowork, mobile"]
    end
    R[("Relay<br/>PHP + PostgreSQL<br/>teams: acme, lab, private")]
    CA <-- "HTTPS: board, messages,<br/>conflict check" --> R
    CB <-- "HTTPS" --> R
    CC <-- "MCP connector (OAuth)" --> R

• Hooks register the session at start, send a heartbeat (which also updates branch and claim), check git commit/git push before they run, and deliver new messages after tool calls and with every prompt.
• listen runs in the background in every session and holds a long-poll open, so a waiting session wakes up within seconds when a message arrives.
• Messages are data, never instructions. A session answers factual questions itself and takes anything that needs a decision to its own user. It never acts on another session's request.
• A board page at the relay's root URL shows the live board in the browser.
• Local mode uses the same client, hooks and commands. Instead of a relay server it answers the requests itself from a file on your machine (one lock, so parallel sessions never lose a write). Adding a team relay later changes nothing for the sessions themselves.

Quick start

Alone on one machine

/plugin marketplace add dimitrihilverda/claude-session-relay
/plugin install session-relay@claude-session-relay

Restart Claude Code. Every session now starts with "Session relay: this session is you-myrepo-1a2b, local (only your sessions on this machine see it, no server)", followed by the board of your sessions on this machine. Your sessions block each other's colliding commits and pushes, and they can message each other. session-relay relays shows the local relay.

Want to choose which folders take part, or another person name? Make it explicit:

session-relay relay add-local local --person me
session-relay folder ~/projects local private

From the moment a config file exists, folders you don't map stay off, as with a team relay.

With a team

Three steps: run a relay, install the plugin, use it.

1. Run a relay (once per team)

cd server
cp .env.example .env        # set a strong RELAY_DB_PASS
docker compose up -d        # relay on port 8080, migrations run automatically
docker compose exec relay relay person:create alice   # prints Alice's token once
docker compose exec relay relay person:create bob
docker compose exec relay relay team:create acme
docker compose exec relay relay team:add acme alice
docker compose exec relay relay team:add acme bob

Put it behind HTTPS. With Caddy that is one line in a Caddyfile:

relay.example.com {
	reverse_proxy localhost:8080
}

Other commands: relay person:revoke <name> (the token stops working), relay team:list, relay team:rename <old> <new>, relay team:remove <team> <person> (their sessions in that team are removed at once), relay cleanup (the compose file already runs it daily). Running person:create again for an existing name issues a new token and invalidates the old one.

A person can be in several teams. Someone who is only in team acme cannot see anything of another team on the same relay: not its sessions, not its people, not even whether a session name exists (the relay answers exactly as for a name that does not exist).

2. Install the plugin (every developer)

In Claude Code:

/plugin marketplace add dimitrihilverda/claude-session-relay
/plugin install session-relay@claude-session-relay

Then tell the client about the relay and which folders belong to which team (the client is session-relay in the plugin's client/ folder; /session-relay:session setup walks you through it):

session-relay relay add acme https://relay.example.com <your-token> alice
session-relay folder ~/work/acme acme acme        # sessions here join team acme
session-relay folder ~/hobby acme private         # only my own sessions see these
session-relay folders

The longest matching folder wins. A session started anywhere else stays off the relay; run session-relay register there if you want it on after all (private by default). You can add several relays, for example one per organisation.

Restart Claude Code. At the start of every session in a mapped folder you will see "Session relay: this session is alice-myrepo-1a2b", followed by your team's board.

Coming from the earlier Dutch client (~/.claude/sessie-relay.json)? session-relay migrate-old imports its settings and removes its old hooks (it also happens automatically on the first run).

3. Use it

Mostly you don't have to: the hooks do the work. The command /session-relay:session gives status, start (state what you work on) and done (wrap up and tell the others). Claude uses the client for messages, for example:

session-relay ask bob-myrepo-9f3c "Are you done with src/billing/?" --session alice-myrepo-1a2b
session-relay board

Open the relay's URL in a browser and enter your token to see the board.

Use from claude.ai / Cowork

People who use Claude without a local Claude Code (claude.ai, the desktop and mobile apps, Cowork) can add the relay as a remote MCP connector. They get the same board, messages and conflict check, with the same team isolation.

claude.ai, Desktop, Cowork: Settings > Connectors > Add custom connector, and enter https://relay.example.com/mcp as the URL. Claude then opens the relay's consent page: paste your relay token (the one from person:create) and click Approve. Claude connects through OAuth (dynamic client registration, PKCE); your relay token stays on that page and is never given to Claude. person:revoke, or running person:create again, also ends these connections.

Claude Code (without the plugin, or on a machine without PowerShell) can use the same endpoint with a header:

claude mcp add --transport http session-relay https://relay.example.com/mcp \
  --header "Authorization: Bearer <your-token>"

Clients that start a local process (a claude_desktop_config.json, MCP inspectors) can use the stdio bridge instead. It needs only PHP 8.4+ (no database) and forwards every tool call to the relay:

{ "mcpServers": { "session-relay": {
  "command": "php",
  "args": ["/path/to/claude-session-relay/server/bin/relay-mcp"],
  "env": { "RELAY_URL": "https://relay.example.com", "RELAY_TOKEN": "<your-token>" }
} } }

The tools are whoami, board, register, unregister, check, send, ask, answer and inbox. A cloud session is called <you>-cloud-<label>.

What the cloud variant lacks: there are no hooks. Nothing registers, sends heartbeats, checks before a commit or push, or delivers messages automatically. Claude has to call register at the start (and again now and then as a heartbeat), inbox regularly and check before a commit or push. The server tells Claude this when it connects, but it is good to remind Claude in your project instructions.

This needs public_url in config.php (or RELAY_PUBLIC_URL in .env): the relay's public HTTPS address, for example https://relay.example.com. The OAuth metadata is built from it, it must match the URL people enter exactly, and /mcp only accepts browser requests from that origin. Without it, /mcp, /oauth/* and the OAuth /.well-known documents answer 503; the rest of the relay keeps working. Client registration is rate limited (20 per address per hour, 500 unused clients per day in total). The web server must pass every path to public/index.php, including /.well-known/oauth-protected-resource, /.well-known/oauth-authorization-server, /oauth/* and /mcp, and must pass the Authorization header on to PHP.

Conflict rules

• The repository is recognised by its origin remote, so different folder names on different machines still match.
• On a relay server, a person's own sessions never block each other. In local mode every session is yours, so there they do: that is what local mode is for.
• Your user can always go ahead: Claude asks for confirmation and appends # session-relay:override to the command.
• A session is live while it has sent a heartbeat in the last 10 minutes.

Requirements

• Claude Code with plugin support.
• Windows: Windows PowerShell 5.1 (built in) and Git Bash (which Claude Code uses for hooks). macOS/Linux: PowerShell 7 (pwsh) and bash.
• git 2.31 or newer.
• Only for a team relay: Docker, or PHP 8.4+ with pdo_pgsql and PostgreSQL. Local mode needs no server.

Privacy and security

Full details: Privacy.

• In local mode nothing travels at all: the board and the messages stay in a file in ~/.claude/session-relay/ on your machine.
• With a relay, only metadata travels: session names, repository and branch names, file paths and short message texts. No code.
• Tokens are 32 random bytes and are stored only as a SHA-256 hash.
• Every API call needs a token. A person can only change their own sessions and read their own messages, and session names must start with that person's name.
• Team isolation is enforced on the server, in one SQL rule used by every endpoint; anything you may not see behaves exactly like something that does not exist. Known residuals: message ids are global and sequential, and response timing is not padded.
• Messages from other sessions are presented to Claude as data, never as instructions.

Development

# server tests (PHPUnit against a real PostgreSQL)
docker compose -f server/docker-compose.test.yml -p csr run --rm php composer install
docker compose -f server/docker-compose.test.yml -p csr run --rm php vendor/bin/phpunit

# client end-to-end tests against a local relay (Windows)
powershell -NoProfile -ExecutionPolicy Bypass -File tests/client-smoke.ps1
pwsh -NoProfile -File tests/client-smoke.ps1 -Shell pwsh

# client tests that need no relay (including local mode)
powershell -NoProfile -ExecutionPolicy Bypass -File tests/client-offline.ps1

Databases created by the first (Dutch-named) version of the relay are upgraded in place by relay migrate; existing people end up in a team called default (rename it with team:rename).

License

MIT, see LICENSE.