diff --git a/web/src/test/setup.ts b/web/src/test/setup.ts
index 0ec51be87d..e91ecf8ff3 100644
--- a/web/src/test/setup.ts
+++ b/web/src/test/setup.ts
@@ -226,7 +226,6 @@ afterEach(() => {
     window.sessionStorage?.clear()
   }
   vi.unstubAllEnvs()
-  vi.restoreAllMocks() // Restore mocks but preserve global stubs (e.g., localStorage) (#20007)
   vi.clearAllMocks()
 })
 
diff --git a/web/vite.config.ts b/web/vite.config.ts
index ee95acf167..ebf47373e5 100644
--- a/web/vite.config.ts
+++ b/web/vite.config.ts
@@ -321,7 +321,7 @@ export default defineConfig(({ mode }) => ({
     isolate: true,
     // CI: use threads pool instead of forks to prevent OOM from subprocess spawn storm (#20007)
     // Threads share memory, no fork overhead. Local dev uses default (forks) for stronger isolation.
-    pool: process.env.CI ? 'threads' : undefined,
+    // pool: process.env.CI ? 'threads' : undefined,  // Reverted: threads share memory, can cause mock cross-contamination
     coverage: {
       provider: 'v8',
       // Disable coverage.all to prevent force-importing source files that trigger