[v2] CJS AJV validator subpath crashes when reading exported Ajv

[morluto]

What happened?

CommonJS consumers cannot read the Ajv export from the AJV validator subpath.

Both @modelcontextprotocol/server and @modelcontextprotocol/client expose ./validators/ajv through a require condition, but the generated CJS output references an ESM alias that does not exist in the CJS module scope.

Object.defineProperty(exports, 'Ajv', {
  enumerable: true,
  get: function () {
    return import_ajv.Ajv;
  }
});

Accessing that export throws:

ReferenceError: import_ajv is not defined

This affects both package subpaths:

• @modelcontextprotocol/server/validators/ajv
• @modelcontextprotocol/client/validators/ajv

The issue is specifically the Ajv getter. Other exports from the same subpath, such as AjvJsonSchemaValidator and addFormats, are reachable.

Generated-output shape:

CJS subpath file
  dist/validators/ajv.cjs

  const require_ajvProvider = require('../ajvProvider-*.cjs')
          |
          |-- exports.addFormats = require_ajvProvider.addFormats              ok
          |-- exports.AjvJsonSchemaValidator = require_ajvProvider...          ok
          |
          `-- exports.Ajv getter
                    |
                    `-- return import_ajv.Ajv                                 crash
                               ^^^^^^^^^^
                               no binding with this name exists in ajv.cjs

Provider chunk
  dist/ajvProvider-*.cjs

  exports.import_ajv = ...
          |
          `-- correct CJS lookup would be require_ajvProvider.import_ajv.Ajv

What did you expect?

A CommonJS consumer should be able to require the documented AJV validator subpath and read the exported Ajv symbol without a ReferenceError.

For example:

const { Ajv, addFormats, AjvJsonSchemaValidator } = require('@modelcontextprotocol/server/validators/ajv');

const ajv = new Ajv({ strict: true, allErrors: true });
addFormats(ajv);
const validator = new AjvJsonSchemaValidator(ajv);

Code to reproduce

// repro.cjs
const serverAjv = require('@modelcontextprotocol/server/validators/ajv');
const clientAjv = require('@modelcontextprotocol/client/validators/ajv');

console.log(serverAjv.Ajv);
console.log(clientAjv.Ajv);

Run:

node repro.cjs

Observed result:

ReferenceError: import_ajv is not defined

Minimal direct probes:

node -e "const m = require('@modelcontextprotocol/server/validators/ajv'); m.Ajv"
node -e "const m = require('@modelcontextprotocol/client/validators/ajv'); m.Ajv"

SDK version

@modelcontextprotocol/server@2.0.0-beta.2
@modelcontextprotocol/client@2.0.0-beta.2

Area

Server / Client packaging, CJS validator subpath exports.