@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.