Report a Tripod or Cinematic switch the aircraft did not take

On the Mavic Pro the TRIPOD_MODE_ENABLED write succeeds but the flight
controller keeps Tripod off, and the panel showed "Tripod on" for a moment
before silently flipping back. The gate now reads the key back after the write
and refuses with "The aircraft kept Tripod off." when it did not change.

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

Fly App/lib/fly/safety_gate.dart

@@ -942,10 +942,21 @@ class SafetyGate {
               : 'Speed drops to about 1 m/s and the sticks become very gentle.'),
       ];
 
-  Future<void> setSlowMode({required bool cinematic, required bool on}) async {
+  /// The write can succeed while the flight controller keeps the old value (a
+  /// Mavic Pro kept Tripod off on the ground and in the simulator), so it is
+  /// read back after [settle] and a refusal is reported instead of the switch
+  /// silently flipping back.
+  Future<void> setSlowMode({required bool cinematic, required bool on, Duration settle = const Duration(milliseconds: 800)}) async {
     final List<GateCheck> checks = checkSlowMode(cinematic: cinematic, on: on);
     if (checks.any((GateCheck c) => c.blocks)) throw MissionRefused(checks);
-    await dji.setKey(DjiKey.flightController(cinematic ? 'CINEMATIC_MODE_ENABLED' : 'TRIPOD_MODE_ENABLED'), on);
+    final DjiKey key = DjiKey.flightController(cinematic ? 'CINEMATIC_MODE_ENABLED' : 'TRIPOD_MODE_ENABLED');
+    await dji.setKey(key, on);
+    await Future<void>.delayed(settle);
+    final Object? now = await dji.getKey(key);
+    if (now is bool && now != on) {
+      final String name = cinematic ? 'Cinematic' : 'Tripod';
+      throw MissionRefused(<GateCheck>[GateCheck.block('The aircraft kept $name ${now ? 'on' : 'off'}.')]);
+    }
   }
 
   // ── Hyperlapse (plan P7) ────────────────────────────────────────────────────

Fly App/test/fly/p7_modes_test.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:latlong2/latlong.dart' show LatLng;
+import 'package:pilotvault_fly/dji_service.dart';
 import 'package:pilotvault_fly/flight_model.dart';
 import 'package:pilotvault_fly/fly/action_rail_state.dart';
 import 'package:pilotvault_fly/fly/fly_prefs.dart';
@@ -146,12 +147,21 @@ void main() {
     test('Tripod and Cinematic are key writes behind the gate', () async {
       final FakeDjiService dji = FakeDjiService();
       final SafetyGate g = SafetyGate(model: _model(telemetryTick()), dji: dji);
-      await g.setSlowMode(cinematic: false, on: true);
+      await g.setSlowMode(cinematic: false, on: true, settle: Duration.zero);
       expect(dji.calls.last, 'setKey(TRIPOD_MODE_ENABLED, true)');
-      await g.setSlowMode(cinematic: true, on: false);
+      await g.setSlowMode(cinematic: true, on: false, settle: Duration.zero);
       expect(dji.calls.last, 'setKey(CINEMATIC_MODE_ENABLED, false)');
     });
 
+    test('a Tripod write the aircraft ignores is reported, not silent', () async {
+      final _KeepsTripodOff dji = _KeepsTripodOff();
+      final SafetyGate g = SafetyGate(model: _model(telemetryTick()), dji: dji);
+      await expectLater(
+        g.setSlowMode(cinematic: false, on: true, settle: Duration.zero),
+        throwsA(isA<MissionRefused>().having((MissionRefused e) => e.toString(), 'message', contains('kept Tripod off'))),
+      );
+    });
+
     test('Free hyperlapse: frames from the video length, then the camera\'s interval mode', () async {
       const HyperlapseSpec h = HyperlapseSpec(intervalSeconds: 3, videoSeconds: 10);
       expect(h.frames, 250);
@@ -339,3 +349,9 @@ class _FlatGround implements ElevationSource {
   @override
   Future<List<double>> elevations(List<LatLng> points) async => List<double>.filled(points.length, 12);
 }
+
+/// A flight controller that accepts the Tripod write and keeps it off (Mavic Pro, 2026-10-22).
+class _KeepsTripodOff extends FakeDjiService {
+  @override
+  Future<Object?> getKey(DjiKey key) async => key.key == 'TRIPOD_MODE_ENABLED' ? false : super.getKey(key);
+}