Shut down Orin: confirmed poweroff, sent once with the hello's boot_id

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DDwfd6Ki8UfG4hK6W5YpJz

lib/main.dart

@@ -260,6 +260,12 @@ class LinkBar extends StatelessWidget {
                 icon: const Icon(Icons.checklist),
                 label: const Text('Captures'),
               ),
+              if (b.state == LinkState.up && b.hello?['boot_id'] is String)
+                TextButton.icon(
+                  onPressed: () => shutDownOrin(context, b),
+                  icon: const Icon(Icons.power_settings_new),
+                  label: const Text('Shut down Orin'),
+                ),
             ],
           ),
         ),
@@ -268,6 +274,57 @@ class LinkBar extends StatelessWidget {
   }
 }
 
+/// Confirm, then send `poweroff` once (contracts BOUNDARY.md): it carries this
+/// connection's boot id, so it can never take effect on a later boot.
+Future<void> shutDownOrin(BuildContext context, Boundary b) async {
+  final host = b.hello?['host'] ?? 'the Orin';
+  final yes = await showDialog<bool>(
+    context: context,
+    builder: (context) => AlertDialog(
+      title: Text('Shut down $host?'),
+      content: const Text(
+        'Recording stops and the session is closed cleanly. '
+        'The Orin stays off until its power button is pressed.',
+      ),
+      actions: [
+        TextButton(
+          onPressed: () => Navigator.of(context).pop(false),
+          child: const Text('Cancel'),
+        ),
+        FilledButton(
+          style: FilledButton.styleFrom(backgroundColor: Colors.red.shade700),
+          onPressed: () => Navigator.of(context).pop(true),
+          child: const Text('Shut down'),
+        ),
+      ],
+    ),
+  );
+  if (yes != true || !context.mounted) return;
+  final messenger = ScaffoldMessenger.of(context);
+  final id = b.commandOnce('poweroff', {
+    'confirm': 'poweroff',
+    'boot_id': b.hello?['boot_id'],
+  });
+  if (id == null) {
+    messenger.showSnackBar(
+      const SnackBar(content: Text('Not sent: no link to the Orin')),
+    );
+    return;
+  }
+  final ack = await b.ackFor(id);
+  messenger.showSnackBar(
+    SnackBar(
+      content: Text(
+        ack == null
+            ? 'No reply: the Orin may or may not be shutting down'
+            : ack.ok
+            ? 'Orin: ${ack.detail}'
+            : 'Refused: ${ack.detail}',
+      ),
+    ),
+  );
+}
+
 class SignalList extends StatelessWidget {
   const SignalList({super.key, required this.boundary});
   final Boundary boundary;