diff --git a/frontend/src/client/admin-rules-edit.ts b/frontend/src/client/admin-rules-edit.ts
index 29c79fc..a01b3a3 100644
--- a/frontend/src/client/admin-rules-edit.ts
+++ b/frontend/src/client/admin-rules-edit.ts
@@ -106,8 +106,10 @@ function fmtDateTime(iso: string): string {
 }
 
 function parseRuleIDFromPath(): string {
-  // /admin/procedural-events/{uuid}/edit
-  const m = /^\/admin\/rules\/([^\/]+)\/edit\/?$/.exec(window.location.pathname);
+  // /admin/procedural-events/{uuid}/edit (canonical, post Slice B.6 rename)
+  // /admin/rules/{uuid}/edit (legacy, 301-redirected by the backend but
+  //   still matched here in case a stale tab or bookmark hits it).
+  const m = /^\/admin\/(?:procedural-events|rules)\/([^\/]+)\/edit\/?$/.exec(window.location.pathname);
   return m ? decodeURIComponent(m[1]) : "";
 }