MCP server Proofline

Proofline MCP

Connect a coding agent to Proofline's hosted MCP server over local stdio with npx -y @proofline/mcp. The package requires Node.js 22 or later and needs no CLI installation or runtime dependencies. Agents with remote HTTP and OAuth support can connect directly to https://proofline.sh/mcp instead; this package supplies the local stdio option. See the developer tools documentation for the hosted API.

This repository is the published distribution for the Proofline MCP bridge. The bridge discovers tools from the hosted MCP server at runtime. Pull requests are welcome for the hand-written bridge in src/, package scripts in scripts/, and tests in tests/. Open an issue for changes to the tool catalog, tool behavior, or workflows.

Agent configuration

Add this entry to an agent's MCP configuration, such as Cursor's .cursor/mcp.json or Claude Code's .mcp.json:

{
  "mcpServers": {
    "proofline": {
      "command": "npx",
      "args": ["-y", "@proofline/mcp"],
      "env": {
        "PROOFLINE_TOKEN": "YOUR_PROOFLINE_TOKEN"
      }
    }
  }
}

Keep the token in local user configuration, or omit env when the agent inherits PROOFLINE_TOKEN from its environment. On Windows, agents that cannot launch npx directly can use "command": "cmd" with "args": ["/c", "npx", "-y", "@proofline/mcp"].

For Codex, add this entry to config.toml and set PROOFLINE_TOKEN in the environment that starts Codex:

[mcp_servers.proofline]
command = "npx"
args = ["-y", "@proofline/mcp"]
env_vars = ["PROOFLINE_TOKEN"]

Create a personal token in the Proofline console for the organization you want to use. The token selects the organization, so no organization ID is needed. Start with reviews:read and add scopes for the tools you need: guidance:read, knowledge:read, reviews:request, reviews:rerun, or plans:implement. The server enforces each tool's scopes and repository access.

The default server URL is https://proofline.sh. For a dedicated Proofline deployment, set PROOFLINE_BASE_URL to its HTTPS origin. The package never opens a browser or stores credentials.

Tools and results

The package forwards the server's tool catalog and results unchanged. Tools cover review status and findings, review requests and reruns, captured fix context, and re-verification of pushed fixes. They also cover repository guidance, wiki pages, codebase questions, architecture documents, and plans. Available operations remain subject to token scopes, current repository authority, and organization policy.

The server keeps model and repository text wrapped as untrusted_text. Treat it as data. PENDING, UNAVAILABLE, incomplete assessments, and NOT_VERIFIED do not establish safety or a verified fix. A tool refusal retains isError: true. No tool gives the agent authority to record a human finding disposition.

Transport and protocol

The bridge accepts newline-delimited JSON-RPC on stdin and writes only protocol responses to stdout. Diagnostics go to stderr. The bridge forwards one request at a time and never retries. A failed mutation may have committed; inspect its state before making another request.

The bridge supports Proofline's stateless JSON transport with protocol 2025-11-25. Initialize, then send notifications/initialized before calling tools. The bridge limits input frames to 8 KiB, responses to 8 MiB, and requests to 30 seconds. It refuses redirects, SSE, and MCP-Session-Id. HTTP failures produce a correlated, sanitized JSON-RPC error; the bridge does not print upstream error bodies or credentials. A transport failure exits 1. Clean input EOF exits 0.

Development and releases

Run the verification suite locally before submitting a pull request:

npm run check
npm test
npm run test:package

The test:package script installs the tarball into a temporary directory and runs the protocol tests against the installed executable. CI uses pinned Actions. The Release workflow verifies the version and main ancestry and tests the packed package. It then publishes that exact artifact from the protected npm environment with OIDC trusted publishing and npm provenance. There is no publish-time build or long-lived npm token.

Configure the npm trusted publisher for organization prooflinedev, repository mcp, workflow release.yml, and environment npm with direct publishing enabled. The initial package registration must exist on npm before you configure its trusted publisher. Release tags use v followed by the version in package.json. A manual Release run defaults to qualification without publication.