diff --git a/apps/pwa/src/hooks/useFocusTrap.ts b/apps/pwa/src/hooks/useFocusTrap.ts
index 12fb791..e55c725 100644
--- a/apps/pwa/src/hooks/useFocusTrap.ts
+++ b/apps/pwa/src/hooks/useFocusTrap.ts
@@ -43,6 +43,16 @@ export function useFocusTrap(
     const first = focusable[0];
     const last = focusable[focusable.length - 1];
 
+    // Containment guard (IN-01): if focus has somehow landed outside the dialog
+    // (programmatic focus, browser quirk), neither boundary condition below
+    // matches and Tab would walk background content. Pull focus back to the
+    // first focusable instead of relying on a boundary-only trap.
+    if (!dialogRef.current.contains(document.activeElement)) {
+      e.preventDefault();
+      first.focus();
+      return;
+    }
+
     if (e.shiftKey) {
       // Shift+Tab: if on first element, wrap to last
       if (document.activeElement === first) {