fix(test): isolate jsdom storage on Node 26

scripts/run-gates.spec.ts

@@ -135,6 +135,23 @@ describe('Oxlint gate', () => {
   })
 })
 
+describe('Node compatibility graph', () => {
+  it('runs the jsdom environment smoke on every advertised Node line', () => {
+    const subject = withPnpmEntrypoint(() => gatesForMode('node-compat'))
+
+    expect(subject.find(item => item.id === 'vitest-jsdom-smoke')).toMatchObject({
+      label: 'Vitest jsdom smoke',
+      args: [
+        '/private/pnpm.cjs',
+        'exec',
+        'vitest',
+        'run',
+        'scripts/vitest-environment.compat.spec.ts',
+      ],
+    })
+  })
+})
+
 describe('Node 24 consumer graph', () => {
   it('owns the eight-command pool and orders restored-artifact consumers', () => {
     const subject = withPnpmEntrypoint(() => gatesForMode('ci-consumers'))

scripts/run-gates.ts

@@ -292,6 +292,11 @@ function nodeCompatSmokeGates(): Gate[] {
       'run',
       'apps/cli/tests/source-launch.compat.spec.ts',
     ], { label: 'dsh source-launch smoke' }),
+    pnpmExec('vitest-jsdom-smoke', [
+      'vitest',
+      'run',
+      'scripts/vitest-environment.compat.spec.ts',
+    ], { label: 'Vitest jsdom smoke' }),
   ]
 }
 

scripts/vitest-environment.compat.spec.ts

@@ -0,0 +1,14 @@
+// @vitest-environment jsdom
+import { describe, expect, it } from 'vitest'
+
+describe('Vitest jsdom compatibility', () => {
+  it('provides isolated browser storage instead of Node process storage', () => {
+    if (process.allowedNodeEnvironmentFlags.has('--webstorage')) {
+      expect(process.execArgv.filter(argument => argument === '--no-webstorage')).toHaveLength(1)
+    }
+    localStorage.setItem('dsh-vitest-storage-probe', 'available')
+
+    expect(localStorage.getItem('dsh-vitest-storage-probe')).toBe('available')
+    localStorage.removeItem('dsh-vitest-storage-probe')
+  })
+})