Proof of Concept: v2 monorepo, package split

.github/workflows/main.yml

@@ -16,32 +16,47 @@ jobs:
         runs-on: ubuntu-latest
 
         steps:
-            - uses: actions/checkout@v4
-            - uses: actions/setup-node@v4
+            - uses: actions/checkout@v6
+
+            - name: Install pnpm
+              uses: pnpm/action-setup@v4
+              id: pnpm-install
+              with:
+                  run_install: false
+            - uses: actions/setup-node@v6
               with:
                   node-version: 24
-                  cache: npm
+                  cache: pnpm
+                  cache-dependency-path: pnpm-lock.yaml
 
-            - run: npm ci
-            - run: npm run check
-            - run: npm run build
+            - run: pnpm install
+            - run: pnpm run check:all
+            - run: pnpm run build:all
 
     test:
         runs-on: ubuntu-latest
         strategy:
             fail-fast: false
             matrix:
-                node-version: [18, 24]
+                node-version: [22, 24]
 
         steps:
-            - uses: actions/checkout@v4
-            - uses: actions/setup-node@v4
+            - uses: actions/checkout@v6
+
+            - name: Install pnpm
+              uses: pnpm/action-setup@v4
+              id: pnpm-install
+              with:
+                  run_install: false
+            - uses: actions/setup-node@v6
               with:
                   node-version: ${{ matrix.node-version }}
-                  cache: npm
+                  cache: pnpm
+                  cache-dependency-path: pnpm-lock.yaml
+
+            - run: pnpm install
 
-            - run: npm ci
-            - run: npm test
+            - run: pnpm test:all
 
     publish:
         runs-on: ubuntu-latest
@@ -55,13 +70,19 @@ jobs:
 
         steps:
             - uses: actions/checkout@v4
+
+            - name: Install pnpm
+              uses: pnpm/action-setup@v4
+              id: pnpm-install
+              with:
+                  run_install: false
             - uses: actions/setup-node@v4
               with:
                   node-version: 24
-                  cache: npm
+                  cache: pnpm
+                  cache-dependency-path: pnpm-lock.yaml
                   registry-url: 'https://registry.npmjs.org'
-
-            - run: npm ci
+            - run: pnpm install
 
             - name: Determine npm tag
               id: npm-tag
@@ -84,6 +105,6 @@ jobs:
                     echo "tag=" >> $GITHUB_OUTPUT
                   fi
 
-            - run: npm publish --provenance --access public ${{ steps.npm-tag.outputs.tag }}
+            - run: pnpm publish --provenance --access public ${{ steps.npm-tag.outputs.tag }}
               env:
                   NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}

.github/workflows/publish.yml

@@ -1,6 +1,8 @@
 name: Publish Any Commit
+
 permissions:
     contents: read
+
 on:
     pull_request:
     push:
@@ -14,14 +16,31 @@ jobs:
         runs-on: ubuntu-latest
 
         steps:
-            - uses: actions/checkout@v4
-            - uses: actions/setup-node@v4
+            - uses: actions/checkout@v6
+
+            - name: Install pnpm
+              uses: pnpm/action-setup@v4
+              with:
+                  run_install: false
+
+            - name: Setup Node.js
+              uses: actions/setup-node@v6
               with:
                   node-version: 24
-                  cache: npm
+                  cache: pnpm
+                  cache-dependency-path: pnpm-lock.yaml
+                  registry-url: 'https://registry.npmjs.org'
+
+            - name: Install dependencies
+              run: pnpm install
+
+            - name: Build packages
+              run: pnpm run build:all
+
+            - name: Publish preview for @modelcontextprotocol/sdk-client
+              working-directory: packages/client
+              run: npx pkg-pr-new publish
 
-            - run: npm ci
-            - name: Build
-              run: npm run build
-            - name: Publish
+            - name: Publish preview for @modelcontextprotocol/sdk-server
+              working-directory: packages/server
               run: npx pkg-pr-new publish

common/eslint-config/eslint.config.mjs

@@ -0,0 +1,63 @@
+// @ts-check
+
+import eslint from '@eslint/js';
+import tseslint from 'typescript-eslint';
+import eslintConfigPrettier from 'eslint-config-prettier/flat';
+import nodePlugin from 'eslint-plugin-n';
+import importPlugin from 'eslint-plugin-import';
+import { fileURLToPath } from 'node:url';
+import path from 'node:path';
+import simpleImportSortPlugin from 'eslint-plugin-simple-import-sort';
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+
+export default tseslint.config(
+    eslint.configs.recommended,
+    ...tseslint.configs.recommended,
+    importPlugin.flatConfigs.recommended,
+    importPlugin.flatConfigs.typescript,
+    {
+        languageOptions: {
+            parserOptions: {
+                // Ensure consumers of this shared config get a stable tsconfig root
+                tsconfigRootDir: __dirname
+            }
+        },
+        linterOptions: {
+            reportUnusedDisableDirectives: false
+        },
+        plugins: {
+            n: nodePlugin,
+            'simple-import-sort': simpleImportSortPlugin
+        },
+        settings: {
+            'import/resolver': {
+                typescript: {
+                    // Let the TS resolver handle NodeNext-style imports like "./foo.js"
+                    extensions: ['.js', '.jsx', '.ts', '.tsx', '.d.ts'],
+                    // Use the tsconfig in each package root (when running ESLint from that package)
+                    project: 'tsconfig.json'
+                }
+            }
+        },
+        rules: {
+            '@typescript-eslint/no-unused-vars': ['error', { argsIgnorePattern: '^_' }],
+            'n/prefer-node-protocol': 'error',
+            '@typescript-eslint/consistent-type-imports': ['error', { disallowTypeAnnotations: false }],
+            'simple-import-sort/imports': 'warn',
+            'simple-import-sort/exports': 'warn'
+        }
+    },
+    {
+        // Ignore generated protocol types everywhere
+        ignores: ['**/spec.types.ts']
+    },
+    {
+        files: ['src/client/**/*.ts', 'src/server/**/*.ts'],
+        ignores: ['**/*.test.ts'],
+        rules: {
+            'no-console': 'error'
+        }
+    },
+    eslintConfigPrettier
+);

common/eslint-config/package.json

@@ -0,0 +1,36 @@
+{
+    "name": "@modelcontextprotocol/eslint-config",
+    "private": true,
+    "main": "eslint.config.mjs",
+    "type": "module",
+    "exports": {
+        ".": "./eslint.config.mjs"
+    },
+    "dependencies": {
+        "typescript": "catalog:"
+    },
+    "repository": {
+        "type": "git",
+        "url": "https://github.com/modelcontextprotocol/typescript-sdk.git"
+    },
+    "bugs": {
+        "url": "https://github.com/modelcontextprotocol/typescript-sdk/issues"
+    },
+    "homepage": "https://github.com/modelcontextprotocol/typescript-sdk/tree/develop/common/eslint-config",
+    "publishConfig": {
+        "registry": "https://npm.pkg.github.com/"
+    },
+    "version": "2.0.0",
+    "devDependencies": {
+        "@eslint/js": "^9.39.1",
+        "eslint": "^9.8.0",
+        "eslint-config-prettier": "^10.1.8",
+        "eslint-import-resolver-typescript": "^4.4.4",
+        "eslint-plugin-import": "^2.32.0",
+        "eslint-plugin-n": "^17.23.1",
+        "eslint-plugin-simple-import-sort": "^12.1.1",
+        "prettier": "3.6.2",
+        "typescript": "^5.5.4",
+        "typescript-eslint": "^8.48.1"
+    }
+}

common/tsconfig/package.json

@@ -0,0 +1,21 @@
+{
+    "name": "@modelcontextprotocol/tsconfig",
+    "private": true,
+    "main": "tsconfig.json",
+    "type": "module",
+    "dependencies": {
+        "typescript": "catalog:"
+    },
+    "repository": {
+        "type": "git",
+        "url": "https://github.com/modelcontextprotocol/typescript-sdk.git"
+    },
+    "bugs": {
+        "url": "https://github.com/modelcontextprotocol/typescript-sdk/issues"
+    },
+    "homepage": "https://github.com/modelcontextprotocol/typescript-sdk/tree/develop/common/ts-config",
+    "publishConfig": {
+        "registry": "https://npm.pkg.github.com/"
+    },
+    "version": "2.0.0"
+}

tsconfig.json → common/tsconfig/tsconfig.json

@@ -1,8 +1,18 @@
 {
     "compilerOptions": {
-        "target": "es2018",
-        "module": "Node16",
-        "moduleResolution": "Node16",
+        "target": "esnext",
+        "lib": ["esnext"],
+        "module": "NodeNext",
+        "moduleResolution": "NodeNext",
+        "allowSyntheticDefaultImports": true,
+        "noFallthroughCasesInSwitch": true,
+        "noUncheckedIndexedAccess": true,
+        "noImplicitOverride": true,
+        "experimentalDecorators": true,
+        "emitDecoratorMetadata": true,
+        "libReplacement": false,
+        "noImplicitReturns": true,
+        "incremental": true,
         "declaration": true,
         "declarationMap": true,
         "sourceMap": true,
@@ -17,7 +27,5 @@
             "pkce-challenge": ["./node_modules/pkce-challenge/dist/index.node"]
         },
         "types": ["node", "vitest/globals"]
-    },
-    "include": ["src/**/*", "test/**/*"],
-    "exclude": ["node_modules", "dist"]
+    }
 }

common/vitest-config/package.json

@@ -0,0 +1,28 @@
+{
+    "name": "@modelcontextprotocol/vitest-config",
+    "private": true,
+    "main": "vitest.config.mjs",
+    "type": "module",
+    "exports": {
+        ".": "./vitest.config.js"
+    },
+    "dependencies": {
+        "typescript": "catalog:"
+    },
+    "repository": {
+        "type": "git",
+        "url": "https://github.com/modelcontextprotocol/typescript-sdk.git"
+    },
+    "bugs": {
+        "url": "https://github.com/modelcontextprotocol/typescript-sdk/issues"
+    },
+    "homepage": "https://github.com/modelcontextprotocol/typescript-sdk/tree/develop/common/vitest-config",
+    "publishConfig": {
+        "registry": "https://npm.pkg.github.com/"
+    },
+    "version": "2.0.0",
+    "devDependencies": {
+        "@modelcontextprotocol/tsconfig": "workspace:^",
+        "vite-tsconfig-paths": "^5.1.4"
+    }
+}

common/vitest-config/tsconfig.json

@@ -0,0 +1,8 @@
+{
+    "include": ["./"],
+    "extends": "@modelcontextprotocol/tsconfig",
+    "compilerOptions": {
+        "noEmit": true,
+        "allowJs": true
+    }
+}

common/vitest-config/vitest.config.js

@@ -0,0 +1,25 @@
+import { defineConfig } from 'vitest/config';
+import tsconfigPaths from 'vite-tsconfig-paths';
+import path from 'node:path';
+import url from 'node:url';
+
+const ignorePatterns = ['**/dist/**'];
+const __dirname = path.dirname(url.fileURLToPath(import.meta.url));
+
+export default defineConfig({
+    test: {
+        globals: true,
+        environment: 'node',
+        include: ['test/**/*.test.ts'],
+        exclude: ignorePatterns,
+        deps: {
+            moduleDirectories: ['node_modules', path.resolve(__dirname, '../../packages'), path.resolve(__dirname, '../../common')]
+        },
+        poolOptions: {
+            threads: {
+                useAtomics: true
+            }
+        }
+    },
+    plugins: [tsconfigPaths()]
+});