diff --git a/nginx.conf b/nginx.conf
index bb1fba0..539e932 100644
--- a/nginx.conf
+++ b/nginx.conf
@@ -27,6 +27,17 @@ server {
     image/svg+xml
     font/woff2;
 
+  # Worker response headers are security-sensitive. Revalidate worker scripts
+  # so a corrected COOP/COEP configuration is not hidden by a year-long cache.
+  location ~* ^/assets/worker-[^/]+\.js$ {
+    try_files $uri =404;
+    expires -1;
+    add_header Cache-Control "no-cache, max-age=0, must-revalidate";
+    add_header Cross-Origin-Opener-Policy "same-origin" always;
+    add_header Cross-Origin-Embedder-Policy "require-corp" always;
+    add_header Cross-Origin-Resource-Policy "same-origin" always;
+  }
+
   # nginx's bundled MIME map does not consistently include .mjs. ONNX Runtime
   # loads these files as JavaScript modules, which browsers reject when served
   # as application/octet-stream.
diff --git a/src/tools/background-remover/worker.ts b/src/tools/background-remover/worker.ts
index e2ef63d..6e56889 100644
--- a/src/tools/background-remover/worker.ts
+++ b/src/tools/background-remover/worker.ts
@@ -15,7 +15,7 @@ self.addEventListener(
     const files = input.files;
 
     if (!files || !Array.isArray(files) || files.length === 0) {
-      post({ type: "error", id, error: "No image provided." });
+      post({ type: "error", id, error: "No image file provided." });
       return;
     }