Merge: fix back button swallowed after a button/ESC overlay close

frontend/src/lib/history.ts

@@ -66,9 +66,17 @@ export function useBackToClose(onClose: () => void): void {
       const idx = overlayStack.lastIndexOf(token);
       if (idx !== -1) {
         // Closed programmatically (not via Back): drop our own history entry, and tell the
-        // remaining overlays' handlers to ignore the resulting popstate.
+        // remaining overlays' handlers to ignore the resulting popstate. A one-shot listener
+        // clears the flag on that very popstate even when NO overlay remains underneath to
+        // consume it — otherwise suppressPop leaks `true` and silently swallows the NEXT
+        // overlay's first Back (reopen-after-button-close → first Back does nothing).
         overlayStack.splice(idx, 1);
         suppressPop = true;
+        const clearSuppress = () => {
+          suppressPop = false;
+          window.removeEventListener("popstate", clearSuppress);
+        };
+        window.addEventListener("popstate", clearSuppress);
         window.history.back();
       }
     };