Contributing

Local setup

git clone https://github.com/studiomeyer-io/mcp-protocol-conformance.git
cd mcp-protocol-conformance
npm install
npm run typecheck
npm test

Add a test for every new behaviour. Tests live in tests/*.test.ts (specs.test.ts for the spec tables, integration.test.ts for suites driven against the tests/fixtures/*.mjs stdio servers, server.test.ts for the MCP-tool dispatch path).
A new suite must declare its name in the allowlist (SUITE_NAMES in src/types.ts), be dispatched in src/suites/full.ts, and be documented in the README compatibility matrix.
Spec-version handling: a check that applies only to a newer spec is gated on a declarative SpecTable field (e.g. if (spec.tasks?.supported) or if (spec.structuredToolOutput)), never on if (spec === "..."). Older specs leave the field unset, so they stay byte-for-byte unaffected.
No any, no shelling out from suite code, no mutation of input arguments.
Run npm run typecheck and npm test before opening a PR.

Semantic versioning. Adding a new optional check is a minor bump. Renaming an existing failure code or removing a suite is a major bump.

Add the version string to the SpecVersionSchema enum and SUPPORTED_SPEC_VERSIONS in src/types.ts.
Create src/specs/<version>.ts exporting a SpecTable (start from the previous version, add only the deltas as optional fields), and register it in src/specs/index.ts.
Gate any new check in the relevant suite on the new SpecTable field, and thread specVersion if the suite opens its own initialize (see src/suites/full.ts + helpers.ts).
Add a tests/fixtures/<name>-server.mjs stdio fixture that advertises the new surface, plus tests in tests/specs.test.ts (table) and tests/integration.test.ts (suite behaviour).
Update the --spec help text in src/cli.ts, the README compatibility matrix + spec references, the mcp.supportedSpecVersions array in package.json, and this CHANGELOG.