diff --git a/common/tsconfig/tsconfig.json b/common/tsconfig/tsconfig.json
index 6db7d705b..2c767ee99 100644
--- a/common/tsconfig/tsconfig.json
+++ b/common/tsconfig/tsconfig.json
@@ -26,6 +26,6 @@
         "paths": {
             "pkce-challenge": ["./node_modules/pkce-challenge/dist/index.node"]
         },
-        "types": ["node", "vitest/globals"]
+        "types": ["node"]
     }
 }
diff --git a/common/vitest-config/package.json b/common/vitest-config/package.json
index 3ae59937e..acdfb5638 100644
--- a/common/vitest-config/package.json
+++ b/common/vitest-config/package.json
@@ -1,14 +1,16 @@
 {
     "name": "@modelcontextprotocol/vitest-config",
     "private": true,
-    "main": "vitest.config.mjs",
     "type": "module",
     "exports": {
-        ".": "./vitest.config.js"
+        ".": "./vitest.config.ts"
     },
     "dependencies": {
         "typescript": "catalog:devTools"
     },
+    "peerDependencies": {
+        "vitest": "catalog:devTools"
+    },
     "repository": {
         "type": "git",
         "url": "https://github.com/modelcontextprotocol/typescript-sdk.git"
diff --git a/common/vitest-config/vitest.config.js b/common/vitest-config/vitest.config.js
deleted file mode 100644
index a2209e9f9..000000000
--- a/common/vitest-config/vitest.config.js
+++ /dev/null
@@ -1,25 +0,0 @@
-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()]
-});
diff --git a/common/vitest-config/vitest.config.ts b/common/vitest-config/vitest.config.ts
new file mode 100644
index 000000000..3d88c5f18
--- /dev/null
+++ b/common/vitest-config/vitest.config.ts
@@ -0,0 +1,11 @@
+import { defineConfig } from 'vitest/config';
+import tsconfigPaths from 'vite-tsconfig-paths';
+
+export default defineConfig({
+    test: {
+        globals: true,
+        environment: 'node',
+        include: ['test/**/*.test.ts']
+    },
+    plugins: [tsconfigPaths()]
+});
diff --git a/examples/client/env.d.ts b/examples/client/env.d.ts
new file mode 100644
index 000000000..9896c472f
--- /dev/null
+++ b/examples/client/env.d.ts
@@ -0,0 +1 @@
+/// <reference types="vitest/globals" />
diff --git a/examples/client/package.json b/examples/client/package.json
index d77d6faf2..89934c345 100644
--- a/examples/client/package.json
+++ b/examples/client/package.json
@@ -43,6 +43,7 @@
         "@modelcontextprotocol/tsconfig": "workspace:^",
         "@modelcontextprotocol/eslint-config": "workspace:^",
         "@modelcontextprotocol/vitest-config": "workspace:^",
-        "tsdown": "catalog:devTools"
+        "tsdown": "catalog:devTools",
+        "vitest": "catalog:devTools"
     }
 }
diff --git a/examples/client/vitest.config.js b/examples/client/vitest.config.ts
similarity index 100%
rename from examples/client/vitest.config.js
rename to examples/client/vitest.config.ts
diff --git a/examples/server/env.d.ts b/examples/server/env.d.ts
new file mode 100644
index 000000000..9896c472f
--- /dev/null
+++ b/examples/server/env.d.ts
@@ -0,0 +1 @@
+/// <reference types="vitest/globals" />
diff --git a/examples/server/package.json b/examples/server/package.json
index f86cc1375..34c743226 100644
--- a/examples/server/package.json
+++ b/examples/server/package.json
@@ -52,6 +52,7 @@
         "@modelcontextprotocol/vitest-config": "workspace:^",
         "@types/cors": "catalog:devTools",
         "@types/express": "catalog:devTools",
-        "tsdown": "catalog:devTools"
+        "tsdown": "catalog:devTools",
+        "vitest": "catalog:devTools"
     }
 }
diff --git a/examples/server/vitest.config.js b/examples/server/vitest.config.ts
similarity index 100%
rename from examples/server/vitest.config.js
rename to examples/server/vitest.config.ts
diff --git a/examples/shared/env.d.ts b/examples/shared/env.d.ts
new file mode 100644
index 000000000..9896c472f
--- /dev/null
+++ b/examples/shared/env.d.ts
@@ -0,0 +1 @@
+/// <reference types="vitest/globals" />
diff --git a/examples/shared/vitest.config.js b/examples/shared/vitest.config.ts
similarity index 100%
rename from examples/shared/vitest.config.js
rename to examples/shared/vitest.config.ts
diff --git a/package.json b/package.json
index 8c756f032..cc5ea7a70 100644
--- a/package.json
+++ b/package.json
@@ -72,7 +72,6 @@
         "typedoc": "catalog:devTools",
         "typescript": "catalog:devTools",
         "typescript-eslint": "catalog:devTools",
-        "vitest": "catalog:devTools",
         "ws": "catalog:devTools",
         "zod": "catalog:runtimeShared"
     },
diff --git a/packages/client/env.d.ts b/packages/client/env.d.ts
new file mode 100644
index 000000000..9896c472f
--- /dev/null
+++ b/packages/client/env.d.ts
@@ -0,0 +1 @@
+/// <reference types="vitest/globals" />
diff --git a/packages/client/vitest.config.js b/packages/client/vitest.config.ts
similarity index 80%
rename from packages/client/vitest.config.js
rename to packages/client/vitest.config.ts
index 2012fa59e..a24e99d61 100644
--- a/packages/client/vitest.config.js
+++ b/packages/client/vitest.config.ts
@@ -3,6 +3,6 @@ import { mergeConfig } from 'vitest/config';
 
 export default mergeConfig(baseConfig, {
     test: {
-        setupFiles: ['./vitest.setup.js']
+        setupFiles: ['./vitest.setup.ts']
     }
 });
diff --git a/packages/client/vitest.setup.js b/packages/client/vitest.setup.ts
similarity index 100%
rename from packages/client/vitest.setup.js
rename to packages/client/vitest.setup.ts
diff --git a/packages/core/env.d.ts b/packages/core/env.d.ts
new file mode 100644
index 000000000..9896c472f
--- /dev/null
+++ b/packages/core/env.d.ts
@@ -0,0 +1 @@
+/// <reference types="vitest/globals" />
diff --git a/packages/core/vitest.config.js b/packages/core/vitest.config.ts
similarity index 100%
rename from packages/core/vitest.config.js
rename to packages/core/vitest.config.ts
diff --git a/packages/middleware/express/env.d.ts b/packages/middleware/express/env.d.ts
new file mode 100644
index 000000000..9896c472f
--- /dev/null
+++ b/packages/middleware/express/env.d.ts
@@ -0,0 +1 @@
+/// <reference types="vitest/globals" />
diff --git a/packages/middleware/express/vitest.config.js b/packages/middleware/express/vitest.config.ts
similarity index 100%
rename from packages/middleware/express/vitest.config.js
rename to packages/middleware/express/vitest.config.ts
diff --git a/packages/middleware/hono/env.d.ts b/packages/middleware/hono/env.d.ts
new file mode 100644
index 000000000..9896c472f
--- /dev/null
+++ b/packages/middleware/hono/env.d.ts
@@ -0,0 +1 @@
+/// <reference types="vitest/globals" />
diff --git a/packages/middleware/hono/vitest.config.js b/packages/middleware/hono/vitest.config.ts
similarity index 100%
rename from packages/middleware/hono/vitest.config.js
rename to packages/middleware/hono/vitest.config.ts
diff --git a/packages/middleware/node/env.d.ts b/packages/middleware/node/env.d.ts
new file mode 100644
index 000000000..9896c472f
--- /dev/null
+++ b/packages/middleware/node/env.d.ts
@@ -0,0 +1 @@
+/// <reference types="vitest/globals" />
diff --git a/packages/middleware/node/vitest.config.js b/packages/middleware/node/vitest.config.ts
similarity index 100%
rename from packages/middleware/node/vitest.config.js
rename to packages/middleware/node/vitest.config.ts
diff --git a/packages/server/env.d.ts b/packages/server/env.d.ts
new file mode 100644
index 000000000..9896c472f
--- /dev/null
+++ b/packages/server/env.d.ts
@@ -0,0 +1 @@
+/// <reference types="vitest/globals" />
diff --git a/packages/server/vitest.config.js b/packages/server/vitest.config.ts
similarity index 100%
rename from packages/server/vitest.config.js
rename to packages/server/vitest.config.ts
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 2099eab0f..99d8b80fc 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -218,9 +218,6 @@ importers:
       typescript-eslint:
         specifier: catalog:devTools
         version: 8.51.0(eslint@9.39.2)(typescript@5.9.3)
-      vitest:
-        specifier: catalog:devTools
-        version: 4.0.16(@types/node@24.10.4)(tsx@4.21.0)(yaml@2.8.2)
       ws:
         specifier: catalog:devTools
         version: 8.18.3
@@ -276,6 +273,9 @@ importers:
       typescript:
         specifier: catalog:devTools
         version: 5.9.3
+      vitest:
+        specifier: catalog:devTools
+        version: 4.0.16(@types/node@24.10.4)(tsx@4.21.0)(yaml@2.8.2)
     devDependencies:
       '@modelcontextprotocol/tsconfig':
         specifier: workspace:^
@@ -311,6 +311,9 @@ importers:
       tsdown:
         specifier: catalog:devTools
         version: 0.18.4(@typescript/native-preview@7.0.0-dev.20260105.1)(typescript@5.9.3)
+      vitest:
+        specifier: catalog:devTools
+        version: 4.0.16(@types/node@24.10.4)(tsx@4.21.0)(yaml@2.8.2)
 
   examples/server:
     dependencies:
@@ -366,6 +369,9 @@ importers:
       tsdown:
         specifier: catalog:devTools
         version: 0.18.4(@typescript/native-preview@7.0.0-dev.20260105.1)(typescript@5.9.3)
+      vitest:
+        specifier: catalog:devTools
+        version: 4.0.16(@types/node@24.10.4)(tsx@4.21.0)(yaml@2.8.2)
 
   examples/shared:
     dependencies:
@@ -871,6 +877,9 @@ importers:
       express:
         specifier: catalog:runtimeServerOnly
         version: 5.2.1
+      vitest:
+        specifier: catalog:devTools
+        version: 4.0.16(@types/node@24.10.4)(tsx@4.21.0)(yaml@2.8.2)
       zod:
         specifier: catalog:runtimeShared
         version: 4.3.5
diff --git a/test/conformance/env.d.ts b/test/conformance/env.d.ts
new file mode 100644
index 000000000..9896c472f
--- /dev/null
+++ b/test/conformance/env.d.ts
@@ -0,0 +1 @@
+/// <reference types="vitest/globals" />
diff --git a/test/conformance/package.json b/test/conformance/package.json
index 253afd9a7..43ff45bfc 100644
--- a/test/conformance/package.json
+++ b/test/conformance/package.json
@@ -49,6 +49,7 @@
         "@modelcontextprotocol/test-helpers": "workspace:^",
         "cors": "catalog:runtimeServerOnly",
         "express": "catalog:runtimeServerOnly",
+        "vitest": "catalog:devTools",
         "zod": "catalog:runtimeShared"
     }
 }
diff --git a/test/conformance/vitest.config.js b/test/conformance/vitest.config.ts
similarity index 100%
rename from test/conformance/vitest.config.js
rename to test/conformance/vitest.config.ts
diff --git a/test/helpers/env.d.ts b/test/helpers/env.d.ts
new file mode 100644
index 000000000..9896c472f
--- /dev/null
+++ b/test/helpers/env.d.ts
@@ -0,0 +1 @@
+/// <reference types="vitest/globals" />
diff --git a/test/helpers/vitest.config.js b/test/helpers/vitest.config.ts
similarity index 100%
rename from test/helpers/vitest.config.js
rename to test/helpers/vitest.config.ts
diff --git a/test/integration/env.d.ts b/test/integration/env.d.ts
new file mode 100644
index 000000000..9896c472f
--- /dev/null
+++ b/test/integration/env.d.ts
@@ -0,0 +1 @@
+/// <reference types="vitest/globals" />
diff --git a/test/integration/vitest.config.js b/test/integration/vitest.config.ts
similarity index 100%
rename from test/integration/vitest.config.js
rename to test/integration/vitest.config.ts