@reachpad/mcp

Development infrastructure for coding agents. A reachpad environment is a cloud development computer an agent operates itself: a repo, a filesystem, installed dependencies, background processes and build state that all survive between calls — not an ephemeral sandbox that forgets.

This is the MCP server. It lets Claude, ChatGPT, Cursor, OpenCode or your own agent create an environment, run commands in it, fork it, and come back to it later, without a developer keeping a laptop open for them.

• It persists. Pause it and the disk and memory are sealed; the next call resumes from that seal, mid-process, rather than rebuilding.
• It forks. Twenty attempts from one prepared state cost a delta each, not twenty rebuilds — because the environment is a snapshot chain, not a machine.
• It keeps secrets out of the box. Credentials are injected at the boundary; their values never enter the environment, the log or the store.
• It is agent-agnostic. The REST API is canonical; this server, the SDK and the CLI are translations of it. Bring your own agent.

The API is the product boundary, not a web UI: reachpad.dev.

Install

npx -y @reachpad/mcp          # stdio, for a local client

In Claude Code:

claude mcp add reachpad -e REACHPAD_IDENTITY_CREDENTIAL=… -- npx -y @reachpad/mcp

Two transports, one implementation

npx @reachpad/mcp                                  # stdio
REACHPAD_MCP_HTTP_PORT=8722 npx @reachpad/mcp      # streamable http

stdio is what a local client talks to; Streamable HTTP is what a remote connector talks to. Same tools, same behaviour — added rather than forked, because two implementations of one surface is how they drift.

The HTTP side answers 405 to GET: every tool here is request/response, and the spec permits declining the server-initiated stream rather than holding a connection open for traffic that never comes. There are no sessions — nothing is held across calls that a restart could not rebuild. And it carries no credential of its own: whatever authorizes the HTTP request is what authorizes reachpad.

Configure

variable	meaning
REACHPAD_ENDPOINT	your reachpad host. Plaintext http:// to anything but loopback is refused before a socket opens.
REACHPAD_IDENTITY_CREDENTIAL	your per-user credential. It names one account and can act for no other — the server takes the identity from the credential's own record, never from the request.
REACHPAD_API_KEY	optional, per-environment scoped and revocable. When set, run_command uses it and needs no identity exchange.
REACHPAD_MCP_HTTP_PORT	serve HTTP instead of stdio.
REACHPAD_MCP_HTTP_HOST	default 127.0.0.1. This process bridges to a control plane with your credentials, so binding it to the world is a decision made on purpose, behind a proxy that terminates TLS.
REACHPAD_MCP_HTTP_TOKEN	bearer token, compared in constant time. Absent, every caller that can reach the port is authorized, and the server says so on stderr.
REACHPAD_MCP_ALLOWED_ORIGINS	comma-separated. A request carrying an unlisted Origin is refused — a browser cannot forge it, which closes DNS rebinding. No Origin at all is a non-browser client and is allowed.

If several credentials are set, the narrowest wins, and a refused credential is never retried under a broader one — falling back would be privilege escalation nobody chose to perform.

Tools

tool	what it does
get_credit_balance()	remaining compute credits. One credit runs one standard environment for one minute.
create_environment(name, repo?, ref?)	a new environment, optionally with a repository cloned into /work
list_environments()	your environments and how many forks each has
get_environment(environment)	what it resumes from — a snapshot carrying memory resumes mid-process; a disk-only one boots
run_command(environment, argv, cwd?, env?, timeout_ms?)	one command, its exit code and its output. A paused environment resumes to serve it.
checkpoint_environment(environment, name?)	fork from the last sealed snapshot; the original is untouched
delete_environment(environment)	archive it and free the plan slot. Nothing is deleted — snapshots and history survive.

Not here, deliberately: exposing a port and starting an agent inside the environment. Both are in reachpad's roadmap and neither is in the fleet yet — a tool that always fails costs a model a turn and teaches it to distrust the rest, so this server advertises nothing it cannot serve.

The rules it is built to

These are the ways a naive client of a streaming exec API misleads a model, and what this one does instead.

• An unterminated stream is UNKNOWN, never success. If the response ends without a terminal event, the tool says so in those words. It is not a zero exit, and an agent must not retry a non-idempotent command on the strength of it.
• Its deadline is looser than the server's, so a server-side answer always wins the race. A client that gives up first turns "your build finished" into "unknown", and the numbers are mirrored from the server rather than guessed.
• Refusals carry remedies, not codes. At your plan limit you get the limit, your current count, and what to do — the numbers come from the server, because a limit hardcoded in a client is a lie the moment your plan changes.
• Results are handles, not payloads. Output is tailed with the dropped byte count named. Build logs can be megabytes, and an MCP result that size destroys the caller's context window.
• A refusal is a result, not a transport error, so the model can read it and act. Only an unknown tool is a protocol error.

Test

node --test 'test/*.test.mjs'

No network and no credentials. The protocol suite spawns the shipped server as a child process and speaks real JSON-RPC over its stdio against a stub control plane on a real socket, so nothing under test is an internal import. One test runs the same arc against a real reachpad and skips when no endpoint is configured.

Repository

This repository is the source. It is deliberately separate from the reachpad backend: this code is public, it is published to npm, and its release workflow holds publishing rights — none of which belong in the same repository as the control plane. Nothing here can read the backend's source, and no job in the backend copies files out to here.

Two server constants are mirrored in src/client.js — the exec grace period and the default exec timeout. A mirrored constant normally rots; this one does not, because the backend's own CI fetches this published package and fails if they disagree. The check lives where the number would change.