fix(mobile): outline bar only while the keyboard is open

The indent/move bar above the keyboard stayed after the keyboard was
closed (back button) because the bullet kept its focus, and covered the
bottom navigation. useKeyboardInset now reports keyboardOpen by
comparing the visible height with the height without keyboard, which
works whether the browser shrinks the page or only the visual viewport.

Release v0.27.1.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/lib/useKeyboardInset.ts

@@ -1,13 +1,42 @@
 import { useEffect, useState } from 'react';
 
-// Space the on-screen keyboard takes at the bottom (0 without keyboard) and the height that stays
-// visible. Fixed bottom sheets use it to sit right above the keyboard instead of behind it (iOS keeps
-// fixed elements on the layout viewport; on Android the inset is usually 0 because the page shrinks).
-export function useKeyboardInset(): { inset: number; visibleHeight: number } {
+// Tallest visible height seen at the current width, i.e. the height without keyboard. Tracked from app
+// start, so it is known before the first field is focused; a new width (rotation) starts over.
+let fullHeight = 0;
+let fullWidth = 0;
+function noteFullHeight() {
+  const vv = window.visualViewport;
+  if (!vv) return;
+  if (window.innerWidth !== fullWidth) {
+    fullWidth = window.innerWidth;
+    fullHeight = 0;
+  }
+  fullHeight = Math.max(fullHeight, Math.round(vv.height));
+}
+if (typeof window !== 'undefined' && window.visualViewport) {
+  noteFullHeight();
+  window.visualViewport.addEventListener('resize', noteFullHeight);
+}
+
+// More than browser bars appearing or disappearing (about 60 px)
+const KEYBOARD_MIN_PX = 150;
+
+// Space the on-screen keyboard takes at the bottom (0 without keyboard), the height that stays visible
+// and whether a keyboard is open. Fixed bottom sheets use the inset to sit right above the keyboard
+// instead of behind it (iOS keeps fixed elements on the layout viewport; on Android the inset is usually
+// 0 because the page shrinks). keyboardOpen compares with the height without keyboard, so it works in
+// both cases; without visualViewport it is unknown and reported as open.
+export function useKeyboardInset(): { inset: number; visibleHeight: number; keyboardOpen: boolean } {
   const read = () => {
     const vv = typeof window !== 'undefined' ? window.visualViewport : null;
-    if (!vv) return { inset: 0, visibleHeight: typeof window !== 'undefined' ? window.innerHeight : 0 };
-    return { inset: Math.max(0, Math.round(window.innerHeight - vv.height - vv.offsetTop)), visibleHeight: Math.round(vv.height) };
+    if (!vv) return { inset: 0, visibleHeight: typeof window !== 'undefined' ? window.innerHeight : 0, keyboardOpen: true };
+    noteFullHeight();
+    const visibleHeight = Math.round(vv.height);
+    return {
+      inset: Math.max(0, Math.round(window.innerHeight - vv.height - vv.offsetTop)),
+      visibleHeight,
+      keyboardOpen: visibleHeight < fullHeight - KEYBOARD_MIN_PX,
+    };
   };
   const [state, setState] = useState(read);