Keep action rows when their key cannot be read

e3917e6 hid any row whose key failed its seeding read, which also hid
"Link remote controller": an action key has no value to read. Unreadable is
now tracked apart from supported, and only rows that show a value hide on it.

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

Fly App/lib/fly/settings/settings_spec.dart

@@ -40,6 +40,9 @@ sealed class SettingSpec {
   /// The key the row reads, or null for app-side rows.
   DjiKey? get key => null;
 
+  /// Whether the row shows the key's value; an unreadable key hides it.
+  bool get readsValue => true;
+
   /// Every key the row needs listened to.
   Iterable<DjiKey> get watched => key == null ? const <DjiKey>[] : <DjiKey>[key!];
 
@@ -47,6 +50,7 @@ sealed class SettingSpec {
     if (requires != null && c.connected && !requires!.enabledFor(c.profile)) return false;
     final DjiKey? k = key;
     if (k != null && c.keys.supported(k) == false) return false;
+    if (k != null && readsValue && c.keys.unreadable(k)) return false;
     return visibleWhen?.call(c) ?? true;
   }
 
@@ -264,6 +268,10 @@ class KeyActionSpec extends SettingSpec {
     super.groundOnly,
   }) : _key = key;
 
+  /// It performs the key's action; there is no value to read.
+  @override
+  bool get readsValue => false;
+
   final DjiKey _key;
   final String button;
   final String? confirmTitle;

Fly App/lib/fly/state/key_state.dart

@@ -11,6 +11,7 @@ import 'settings_overlay.dart';
 /// known to be unsupported, and stays visible (as "—") while still unknown.
 class KeyState extends ChangeNotifier with SettingsOverlay {
   final Map<String, bool> _supported = <String, bool>{};
+  final Set<String> _unreadable = <String>{};
 
   /// True / false once asked, null while unknown.
   bool? supported(DjiKey key) => _supported[key.id];
@@ -25,30 +26,34 @@ class KeyState extends ChangeNotifier with SettingsOverlay {
     notifyListeners();
   }
 
-  /// A key the aircraft calls supported but will not read: hidden like an
-  /// unsupported one, until a value turns up after all.
+  /// The aircraft calls the key supported but will not read it (the Mavic Pro
+  /// remote's gimbal dial speed). Rows that show its value hide; action rows,
+  /// which never read it, do not.
+  bool unreadable(DjiKey key) => _unreadable.contains(key.id);
+
   void markUnreadable(String id) {
-    if (_supported[id] == false || reportedSettings.containsKey(id)) return;
-    _supported[id] = false;
+    if (reportedSettings.containsKey(id) || !_unreadable.add(id)) return;
     notifyListeners();
   }
 
   /// One `key` event: `{id, value}`.
   void apply(String id, Object? value) {
-    if (_supported[id] == false) _supported.remove(id);
+    _unreadable.remove(id);
     replaceReported(<String, dynamic>{...reportedSettings, id: value});
     notifyListeners();
   }
 
   /// A new aircraft answers `isKeySupported` afresh.
   void forgetSupport() {
-    if (_supported.isEmpty) return;
+    if (_supported.isEmpty && _unreadable.isEmpty) return;
     _supported.clear();
+    _unreadable.clear();
     notifyListeners();
   }
 
   void clear() {
     _supported.clear();
+    _unreadable.clear();
     clearSettings();
     notifyListeners();
   }

Fly App/test/fly/settings_test.dart

@@ -151,12 +151,24 @@ void main() {
       final TelemetryReducer r = TelemetryReducer(m);
       m.keys.setSupported(SettingsKeys.gimbalDialSpeed, true);
       r.apply(<String, dynamic>{'type': 'key', 'id': SettingsKeys.gimbalDialSpeed.id, 'unreadable': true});
-      expect(m.keys.supported(SettingsKeys.gimbalDialSpeed), isFalse);
+      expect(m.keys.unreadable(SettingsKeys.gimbalDialSpeed), isTrue);
+      final SettingsContext c = SettingsContext(profile: m.profile, keys: m.keys, aircraft: m.aircraft);
+      final SettingSpec dial = spec<SettingSpec>(SettingsTabs.rc, 'gimbalDialSpeed');
+      expect(dial.visible(c), isFalse);
       r.apply(<String, dynamic>{'type': 'key', 'id': SettingsKeys.gimbalDialSpeed.id, 'value': 40});
-      expect(m.keys.supported(SettingsKeys.gimbalDialSpeed), isNot(isFalse));
+      expect(dial.visible(c), isTrue);
       expect(m.keys.value(SettingsKeys.gimbalDialSpeed), 40);
     });
 
+    test('an action row stays when its key cannot be read (it never reads it)', () {
+      final FlightModel m = connectedModel(phantom4);
+      m.keys.setSupported(SettingsKeys.startPairing, true);
+      TelemetryReducer(m).apply(<String, dynamic>{'type': 'key', 'id': SettingsKeys.startPairing.id, 'unreadable': true});
+      final SettingsContext c = SettingsContext(profile: m.profile, keys: m.keys, aircraft: m.aircraft);
+      final SettingSpec link = spec<SettingSpec>(SettingsTabs.rc, 'startPairing');
+      expect(link.visible(c), isTrue);
+    });
+
     test('subscriptions listen only to supported keys and cancel on dispose', () async {
       final FakeDjiService dji = FakeDjiService()..unsupportedKeys.add('ESC_BEEPING_ENABLED');
       final KeyState s = KeyState();