fx
My version of https://github.com/vercel-labs/fx
Star
Fork
Watch
fx tests e2e conformance
7 files
.npmrc
client.ts
expected-failures.yml
package-lock.json
package.json
README.md
run.ts
README.md

MCP conformance baseline #

This package runs the official MCP client conformance suite against the freshly built fx binary. It is pinned to:

  • MCP protocol version 2026-07-28
  • @modelcontextprotocol/conformance@0.2.0-alpha.10
  • conformance repository revision a9896553900a2ef61787b57adfcbbe936a8ab1f9

This directory is an isolated npm subproject. npm owns its checked-in package-lock.json and installs the pinned official runner. Bun executes fx's TypeScript adapter after installation; it does not resolve dependencies here. Do not run bun install or create a Bun lockfile in this directory.

The package requires Node 22 or newer, npm 10 or newer, and the Bun version used by the surrounding E2E suite. Local .npmrc policy requires the lockfile, rejects unsupported engines, and disables dependency lifecycle scripts.

From the repository root:

FX_SOUND=0 zig build
cd tests/e2e/conformance
npm ci
FX_SOUND=0 npm test

npm ci must leave package-lock.json unchanged. Update the lock only when the pinned conformance package changes intentionally. The runner also fails before starting scenarios when the freshly built zig-out/bin/fx is missing.

expected-failures.yml lists individual check IDs rather than whole scenarios. The runner exits nonzero when a new check fails or a listed check starts passing, so any conformance change requires an intentional baseline update.

client.ts uses the runner's scenario/context variables to select the fake Gateway tool calls and requested protocol. It opts into the newer discovery lifecycle for the 2026-07-28 suite; the legacy scenarios use MCP v1. It then launches ./zig-out/bin/fx without implementing MCP messages or transport behavior.