diff --git a/src/features/Workspace/useWorkspaceUrlSync.ts b/src/features/Workspace/useWorkspaceUrlSync.ts
index 59c622ee53..a8bd5836b3 100644
--- a/src/features/Workspace/useWorkspaceUrlSync.ts
+++ b/src/features/Workspace/useWorkspaceUrlSync.ts
@@ -45,6 +45,21 @@ const parseFirstSegment = (pathname: string): string | null => {
   return match ? match[1] : null;
 };
 
+/**
+ * Whether `pathname`'s first segment could be an (as-yet-unresolved) workspace
+ * slug — i.e. it's present and not one of the reserved root segments.
+ *
+ * Top-level rendering only needs to block on the workspace list (to avoid a
+ * false 404 / wrong-scope paint) when this is `true`. On personal / reserved
+ * routes (`/`, `/agent/...`, `/settings/...`) the list isn't required to render,
+ * so callers can show personal context immediately and let the list hydrate in
+ * the background.
+ */
+export const isWorkspaceSlugCandidatePath = (pathname: string): boolean => {
+  const first = parseFirstSegment(pathname);
+  return !!first && !RESERVED_FIRST_SEGMENTS.has(first);
+};
+
 /**
  * URL is the source of truth for workspace context.
  *