gemmein

The distribution home of the Gemmein CLI — the gemmein package on npm, and the release record of the local engine it runs.

Gemmein is the trustworthy backend for AI-built apps: accounts, data, payments — with the boundaries enforced by the platform, not by your app's code. The CLI brings that to your machine: npx gemmein init shapes your product's boundaries in plain language, and gemmein dev runs a real local backend that enforces them while you build.

MCP server

@gemmein/mcp gives a coding agent the whole Gemmein contract as tools — the builder guide, the SDK reference, rule and error explainers, and a live check of an app's access boundaries — read-only against the platform: no tool it ships creates, edits, or deletes anything on Gemmein.

Install for Claude Code:

claude mcp add gemmein -- npx -y @gemmein/mcp

Install for Claude Desktop, Cursor, or any client that takes an mcpServers block:

{
  "mcpServers": {
    "gemmein": {
      "command": "npx",
      "args": ["-y", "@gemmein/mcp"]
    }
  }
}

No environment variables are required to run it.

Tools it serves:

• guide — the full builder's guide, covering auth flow, the seven safety rules, record shapes, links, uploads, contention, payments.
• reference — every SDK method, exact signature, return shape, and error code.
• search_docs — targeted search over both, when it needs one fact.
• explain_rule — any rule's contract, what it's right for, and the mistakes to avoid, or a cheat-sheet of all seven at planning time.
• explain_error — what a GemmeinError code means and exactly what to do about it.
• validate_collection_name — catches a misnamed collection before every read starts returning empty results.
• explain_relay — a gemmein/relays/<name>.json definition in, the sentence the dashboard would show out, or the one refusal naming the field; offline, over the eleven verbs write_record, grant_access, revoke_access, grant_credits, email_person, call_url, fulfil_product, refund_product, grant_plan, revoke_plan and start_run.
• reaffirm_template — the CI harness, ready to copy.
• check_integration — runs an app's isolation and access checks live against itself and hands back structured pass/fail.

The server's full source is in mcp/ (MIT). It is a standalone Node package: cd mcp && npm install && npm run build, then run node dist/index.js. It does not use the Gemmein engine.

Docs: docs.gemmein.com/mcp.

How the launcher works

The npm package you install is a small launcher, published as readable source — what you see in shim/ is exactly what runs on your machine.

On first run it downloads the Gemmein engine, verifies it against SHA-256 hashes pinned inside this package, caches it locally, and runs it. After that one download, everything works fully offline. If a downloaded file ever fails verification, the launcher refuses to run it.

• shim/ — the gemmein npm package (plain JS, no build step)
• manifest/releases.json — every engine release and its file hashes

Licensing

Two licenses, on purpose:

• The MCP server (mcp/, published as @gemmein/mcp) is MIT.
• The npm launcher (shim/) is MIT — read it, audit it, it's yours.
• The downloaded engine is proprietary, under the Gemmein Engine License — you can run and cache it freely for building against Gemmein (offline once cached, even if a version is retired), but not redistribute or extract it. It's also served at downloads.gemmein.com/engine/LICENSE.

Using it

npx gemmein init

Docs: docs.gemmein.com · Questions: hello@gemmein.com