diff --git a/crates/op-host-services/src/design_agent_tools.rs b/crates/op-host-services/src/design_agent_tools.rs
index 86c9ae985..e6c2fa6ca 100644
--- a/crates/op-host-services/src/design_agent_tools.rs
+++ b/crates/op-host-services/src/design_agent_tools.rs
@@ -615,6 +615,18 @@ fn extract_from_schema_entry(entry: &str) -> Option<(String, String)> {
 
 #[cfg(test)]
 mod tests {
+    #[test]
+    fn web_app_prompts_are_not_mobile_seeded() {
+        // A dashboard "web app" is a desktop product — it must not be
+        // seeded 390x844 (regression: the bare "app" word-match did).
+        assert!(!super::root_seed_prompt_is_mobile(
+            "Technical dashboard web app for a utilities company"
+        ));
+        assert!(!super::root_seed_prompt_is_mobile(
+            "Luxury webapp for managing barbershop clients"
+        ));
+    }
+
     #[test]
     fn app_prompts_are_mobile_seeded() {
         assert!(super::root_seed_prompt_is_mobile(