diff --git a/apps/service/src/__tests__/workflow.test.ts b/apps/service/src/__tests__/workflow.test.ts
index eaf2db62f..b8c1343b9 100644
--- a/apps/service/src/__tests__/workflow.test.ts
+++ b/apps/service/src/__tests__/workflow.test.ts
@@ -1,4 +1,4 @@
-import { describe, it, expect, beforeAll, afterAll } from 'vitest'
+import { describe, it, expect, beforeAll, afterAll, inject } from 'vitest'
 import { TestWorkflowEnvironment } from '@temporalio/testing'
 import { Worker } from '@temporalio/worker'
 import path from 'node:path'
@@ -31,10 +31,14 @@ function stubActivities(overrides: Partial<SyncActivities> = {}): SyncActivities
 let testEnv: TestWorkflowEnvironment
 
 beforeAll(async () => {
-  testEnv = await TestWorkflowEnvironment.createLocal()
-}, 120_000)
+  // Connect to the shared dev server started in vitest.global-setup.ts instead of
+  // spawning a new one per file — avoids concurrent startup races under file parallelism.
+  const address = inject('temporalTestServerAddress')
+  testEnv = await TestWorkflowEnvironment.createFromExistingServer({ address })
+}, 30_000)
 
 afterAll(async () => {
+  // teardown() on an existing-server env only closes connections, not the server itself.
   await testEnv?.teardown()
 })
 
diff --git a/apps/service/src/api/app.test.ts b/apps/service/src/api/app.test.ts
index 8a0f9c87a..eccc4629e 100644
--- a/apps/service/src/api/app.test.ts
+++ b/apps/service/src/api/app.test.ts
@@ -1,4 +1,4 @@
-import { describe, expect, it, beforeAll, afterAll } from 'vitest'
+import { describe, expect, it, beforeAll, afterAll, inject } from 'vitest'
 import type { WorkflowClient } from '@temporalio/client'
 import { TestWorkflowEnvironment } from '@temporalio/testing'
 import { Worker } from '@temporalio/worker'
@@ -90,7 +90,10 @@ let worker: Worker
 let workerRunning: Promise<void>
 
 beforeAll(async () => {
-  testEnv = await TestWorkflowEnvironment.createLocal()
+  // Connect to the shared dev server started in vitest.global-setup.ts instead of
+  // spawning a new one per file — avoids concurrent startup races under file parallelism.
+  const address = inject('temporalTestServerAddress')
+  testEnv = await TestWorkflowEnvironment.createFromExistingServer({ address })
   worker = await Worker.create({
     connection: testEnv.nativeConnection,
     taskQueue: 'test-api',
@@ -103,6 +106,7 @@ beforeAll(async () => {
 afterAll(async () => {
   worker?.shutdown()
   await workerRunning
+  // teardown() on an existing-server env only closes connections, not the server itself.
   await testEnv?.teardown()
 })
 
diff --git a/apps/service/vitest.config.ts b/apps/service/vitest.config.ts
index 592756e35..eab0960f4 100644
--- a/apps/service/vitest.config.ts
+++ b/apps/service/vitest.config.ts
@@ -2,6 +2,7 @@ import { defineConfig } from 'vitest/config'
 
 export default defineConfig({
   test: {
+    globalSetup: ['./vitest.global-setup.ts'],
     exclude: ['**/node_modules/**', '**/dist/**', '**/*.integration.test.ts'],
     testTimeout: 60_000,
     hookTimeout: 60_000,
diff --git a/apps/service/vitest.d.ts b/apps/service/vitest.d.ts
new file mode 100644
index 000000000..e23ea7281
--- /dev/null
+++ b/apps/service/vitest.d.ts
@@ -0,0 +1,7 @@
+import 'vitest'
+
+declare module 'vitest' {
+  export interface ProvidedContext {
+    temporalTestServerAddress: string
+  }
+}
diff --git a/apps/service/vitest.global-setup.ts b/apps/service/vitest.global-setup.ts
new file mode 100644
index 000000000..2e51d81c9
--- /dev/null
+++ b/apps/service/vitest.global-setup.ts
@@ -0,0 +1,20 @@
+/**
+ * Vitest global setup: starts ONE Temporal dev server for the entire test run.
+ *
+ * Each test file connects to this shared server via TestWorkflowEnvironment.createFromExistingServer()
+ * rather than calling createLocal() per-file, which avoids concurrent startup races under
+ * Vitest's default file parallelism.
+ */
+import { TestWorkflowEnvironment } from '@temporalio/testing'
+import type { GlobalSetupContext } from 'vitest/node'
+
+let env: TestWorkflowEnvironment | undefined
+
+export async function setup({ provide }: GlobalSetupContext) {
+  env = await TestWorkflowEnvironment.createLocal()
+  provide('temporalTestServerAddress', env.address)
+}
+
+export async function teardown() {
+  await env?.teardown()
+}
diff --git a/e2e/docs.test.ts b/e2e/docs.test.ts
index f63b293d9..7a73ec57d 100644
--- a/e2e/docs.test.ts
+++ b/e2e/docs.test.ts
@@ -7,11 +7,7 @@ const ROOT = join(import.meta.dirname, '..')
 // All plan and design files must start with YYYY-MM-DD-
 const DATE_PATTERN = /^\d{4}-\d{2}-\d{2}-[\w-]+\.md$/
 
-const CHECKED_DIRS = [
-  'docs/plans/active',
-  'docs/plans/completed',
-  'docs/design',
-]
+const CHECKED_DIRS = ['docs/plans/active', 'docs/plans/completed', 'docs/design']
 
 for (const dir of CHECKED_DIRS) {
   describe(`${dir} naming convention`, () => {