diff --git a/apps/ui-server-auth/README.md b/apps/ui-server-auth/README.md
index b65769126..9411a43f9 100644
--- a/apps/ui-server-auth/README.md
+++ b/apps/ui-server-auth/README.md
@@ -23,7 +23,7 @@ pnpm -F @proj-airi/ui-server-auth build
 
 ## Deployment
 
-`pnpm -F @proj-airi/ui-server-auth build` writes to `apps/ui-server-auth/dist`. Vue Router owns `/ui/*`, while Vite assets are served from root `/assets/*` so Cloudflare Pages can serve static files without rewriting nested asset paths. `public/_redirects` scopes the SPA rewrite to `/ui/*`, and the top-level `public/404.html` keeps missing assets and other unknown paths as HTTP 404 responses.
+`pnpm -F @proj-airi/ui-server-auth build` writes to `apps/ui-server-auth/dist`. Vue Router owns `/ui/*`, while Vite assets are served from root `/assets-v2/*` so Cloudflare Pages can serve static files without rewriting nested asset paths. The versioned namespace moves existing clients away from previously poisoned `/assets/*` browser cache entries. Both namespaces use `Cache-Control: public, no-cache`, allowing browsers to retain files only when Pages revalidates them. `public/_redirects` scopes the SPA rewrite to `/ui/*`, and the top-level `public/404.html` keeps missing assets and other unknown paths as HTTP 404 responses.
 
 The production GitHub Actions workflow deploys this app to the Cloudflare Pages project `moeru-ai-airi-auth` with separate auth-account credentials:
 
diff --git a/apps/ui-server-auth/public/_headers b/apps/ui-server-auth/public/_headers
index 7f40d0894..5d3ccc5dd 100644
--- a/apps/ui-server-auth/public/_headers
+++ b/apps/ui-server-auth/public/_headers
@@ -1,4 +1,5 @@
 /assets/*
-  cache-control: max-age=31536000
-  cache-control: immutable
+  cache-control: public, no-cache
 
+/assets-v2/*
+  cache-control: public, no-cache
diff --git a/apps/ui-server-auth/src/cloudflare-pages-routing.test.ts b/apps/ui-server-auth/src/cloudflare-pages-routing.test.ts
index d72b3801f..85d967346 100644
--- a/apps/ui-server-auth/src/cloudflare-pages-routing.test.ts
+++ b/apps/ui-server-auth/src/cloudflare-pages-routing.test.ts
@@ -23,4 +23,12 @@ describe('cloudflare Pages routing', () => {
     expect(notFoundPage).toContain('<title>Page not found</title>')
     expect(redirects).toContain('/ui/* / 200')
   })
+
+  it('requires old and current asset namespaces to revalidate cached responses', async () => {
+    const headers = await readFile(resolve(publicDirectory, '_headers'), 'utf8')
+
+    expect(headers).toContain('/assets/*\n  cache-control: public, no-cache')
+    expect(headers).toContain('/assets-v2/*\n  cache-control: public, no-cache')
+    expect(headers).not.toContain('immutable')
+  })
 })
diff --git a/apps/ui-server-auth/vite.config.ts b/apps/ui-server-auth/vite.config.ts
index 23afb1ccb..d85d159db 100644
--- a/apps/ui-server-auth/vite.config.ts
+++ b/apps/ui-server-auth/vite.config.ts
@@ -12,6 +12,16 @@ import VueRouter from 'vue-router/vite'
 
 import { defineConfig } from 'vite'
 
+// NOTICE:
+// Keep this namespace distinct from `/assets/`, where an earlier Pages SPA
+// fallback allowed missing JavaScript URLs to cache index.html as immutable.
+// Root cause: the old asset cache policy outlived the deployment that restored
+// those files, so affected browsers cannot observe corrected response headers.
+// Source/context: `apps/ui-server-auth/public/_headers` and `public/404.html`.
+// Removal condition: keep the namespace permanently; reusing `/assets/` can
+// reactivate poisoned browser entries that remain fresh for up to one year.
+const assetsDirectory = 'assets-v2'
+
 export default defineConfig({
   base: '/',
   optimizeDeps: {
@@ -44,6 +54,7 @@ export default defineConfig({
     },
   },
   build: {
+    assetsDir: assetsDirectory,
     emptyOutDir: true,
     manifest: true,
     outDir: resolve(join(import.meta.dirname, 'dist')),
@@ -58,8 +69,8 @@ export default defineConfig({
           // Keep analytics as the source-domain name, but explicitly map its
           // public URL to a neutral chunk name that filter lists cannot infer.
           return containsAnalyticsModule
-            ? 'assets/chunk-[hash].js'
-            : 'assets/[name]-[hash].js'
+            ? `${assetsDirectory}/chunk-[hash].js`
+            : `${assetsDirectory}/[name]-[hash].js`
         },
       },
     },