diff --git a/frontend/src/banner.ts b/frontend/src/banner.ts
index 1c6d63b..7fc6ec3 100644
--- a/frontend/src/banner.ts
+++ b/frontend/src/banner.ts
@@ -6,6 +6,8 @@ export interface BannerEntry {
   message: string;
 }
 
+// Non-error banners clean themselves up; errors stay until the user
+// dismisses them, so a failure can't silently vanish before it's read.
 const DISMISS_AFTER_MS = 8000;
 
 let banners: BannerEntry[] = [];
@@ -25,7 +27,9 @@ function show(severity: BannerSeverity, message: string): void {
   const id = nextId++;
   banners = [{ id, severity, message }, ...banners];
   notify();
-  setTimeout(() => dismiss(id), DISMISS_AFTER_MS);
+  if (severity !== "error") {
+    setTimeout(() => dismiss(id), DISMISS_AFTER_MS);
+  }
 }
 
 export function showError(message: string): void {