Stabilize terminal resizing around input mode changes

apps/mobile_app/lib/features/terminal/terminal_page.dart

@@ -46,6 +46,7 @@ class TerminalPage extends ConsumerStatefulWidget {
 class _TerminalPageState extends ConsumerState<TerminalPage>
     with WidgetsBindingObserver {
   static const Duration _historySeedDelay = Duration(milliseconds: 120);
+  static const Duration _terminalResizeSettleDelay = Duration(milliseconds: 240);
   static const List<_QuickTerminalKey> _editingControlKeys = [
     _QuickTerminalKey(keyId: 'esc', label: 'Esc', input: '\u001b'),
     _QuickTerminalKey(keyId: 'tab', label: 'Tab', input: '\t'),
@@ -147,6 +148,7 @@ class _TerminalPageState extends ConsumerState<TerminalPage>
   late final TerminalSnapshotStorage _snapshotStorage;
   late final Listenable _pageStateListenable;
   Timer? _historySeedTimer;
+  Timer? _terminalResizeSettleTimer;
   Timer? _snapshotPersistTimer;
   String? _pendingHistorySeed;
   bool _receivedSocketFrame = false;
@@ -156,6 +158,7 @@ class _TerminalPageState extends ConsumerState<TerminalPage>
   bool _awaitingReconnectRestore = false;
   bool _shouldReconnectOnResume = false;
   bool _showExpandedControls = false;
+  bool _terminalAutoResizeEnabled = true;
   _TerminalInputMode _inputMode = _TerminalInputMode.read;
   TerminalConnectionState? _lastConnectionState;
 
@@ -189,7 +192,7 @@ class _TerminalPageState extends ConsumerState<TerminalPage>
       _diagnosticLog.add('ui.terminal.key', normalizedInput);
       _coordinator.sendInput(normalizedInput);
     };
-    _applyInputMode();
+    _applyInputMode(freezeResize: false);
     unawaited(_bootstrapTerminal());
   }
 
@@ -198,6 +201,7 @@ class _TerminalPageState extends ConsumerState<TerminalPage>
     WidgetsBinding.instance.removeObserver(this);
     _pageStateListenable.removeListener(_handlePageStateChanged);
     _historySeedTimer?.cancel();
+    _terminalResizeSettleTimer?.cancel();
     _snapshotPersistTimer?.cancel();
     unawaited(_persistTerminalSnapshot());
     _terminalFocusNode.dispose();
@@ -226,6 +230,17 @@ class _TerminalPageState extends ConsumerState<TerminalPage>
     }
   }
 
+  @override
+  void didChangeMetrics() {
+    if (_inputMode == _TerminalInputMode.edit) {
+      _cancelTerminalResizeSettle();
+      _setTerminalAutoResizeEnabled(false);
+      return;
+    }
+
+    _freezeTerminalResizeUntilSettled();
+  }
+
   Future<void> _openSiblingTerminal() async {
     final project = widget.project;
     if (project == null) {
@@ -329,8 +344,17 @@ class _TerminalPageState extends ConsumerState<TerminalPage>
     _applyInputMode();
   }
 
-  void _applyInputMode() {
+  void _applyInputMode({bool freezeResize = true}) {
     _coordinator.setBackendResizeEnabled(_inputMode != _TerminalInputMode.edit);
+    if (_inputMode == _TerminalInputMode.edit) {
+      _cancelTerminalResizeSettle();
+      _setTerminalAutoResizeEnabled(false);
+    } else if (freezeResize) {
+      _freezeTerminalResizeUntilSettled();
+    } else {
+      _cancelTerminalResizeSettle();
+      _setTerminalAutoResizeEnabled(true);
+    }
     _terminalFocusNode.canRequestFocus = _inputMode == _TerminalInputMode.edit;
     if (_inputMode == _TerminalInputMode.edit) {
       _terminalFocusNode.requestFocus();
@@ -340,6 +364,34 @@ class _TerminalPageState extends ConsumerState<TerminalPage>
     _terminalFocusNode.unfocus();
   }
 
+  void _freezeTerminalResizeUntilSettled() {
+    _setTerminalAutoResizeEnabled(false);
+    _terminalResizeSettleTimer?.cancel();
+    _terminalResizeSettleTimer = Timer(_terminalResizeSettleDelay, () {
+      _terminalResizeSettleTimer = null;
+      if (!mounted || _inputMode == _TerminalInputMode.edit) {
+        return;
+      }
+
+      _setTerminalAutoResizeEnabled(true);
+    });
+  }
+
+  void _cancelTerminalResizeSettle() {
+    _terminalResizeSettleTimer?.cancel();
+    _terminalResizeSettleTimer = null;
+  }
+
+  void _setTerminalAutoResizeEnabled(bool enabled) {
+    if (_terminalAutoResizeEnabled == enabled || !mounted) {
+      return;
+    }
+
+    setState(() {
+      _terminalAutoResizeEnabled = enabled;
+    });
+  }
+
   void _handleTerminalSurfaceTap() {
     if (_inputMode != _TerminalInputMode.edit) {
       return;
@@ -721,7 +773,7 @@ class _TerminalPageState extends ConsumerState<TerminalPage>
                       controller: _terminalViewController,
                       focusNode: _terminalFocusNode,
                       autofocus: false,
-                      autoResize: false,
+                      autoResize: _terminalAutoResizeEnabled,
                       keyboardType: TextInputType.multiline,
                       deleteDetection: true,
                       readOnly: _inputMode == _TerminalInputMode.read,

apps/mobile_app/test/features/terminal/terminal_page_input_test.dart

@@ -72,13 +72,30 @@ void main() {
     expect(terminalView.deleteDetection, isTrue);
   });
 
-  testWidgets('terminal view disables auto resize and text reflow', (tester) async {
+  testWidgets('terminal view freezes auto resize while editing and restores it after returning to read', (tester) async {
     await _pumpTerminalPage(tester);
 
-    final terminalView = tester.widget<TerminalView>(find.byType(TerminalView));
+    var terminalView = tester.widget<TerminalView>(find.byType(TerminalView));
 
-    expect(terminalView.autoResize, isFalse);
+    expect(terminalView.autoResize, isTrue);
     expect(terminalView.terminal.reflowEnabled, isFalse);
+
+    await tester.tap(find.byKey(const Key('terminal_mode_edit_button')));
+    await tester.pump();
+
+    terminalView = tester.widget<TerminalView>(find.byType(TerminalView));
+    expect(terminalView.autoResize, isFalse);
+
+    await tester.tap(find.byKey(const Key('terminal_mode_read_button')));
+    await tester.pump();
+
+    terminalView = tester.widget<TerminalView>(find.byType(TerminalView));
+    expect(terminalView.autoResize, isFalse);
+
+    await tester.pump(const Duration(milliseconds: 260));
+
+    terminalView = tester.widget<TerminalView>(find.byType(TerminalView));
+    expect(terminalView.autoResize, isTrue);
   });
 
   testWidgets(