Read a navigate-back action without a destination

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0147gqWiq3xoEdAGwWSpq9JK

Author: claude

CHANGELOG.md

@@ -1,5 +1,8 @@
 ## Unreleased
 
+- A navigate-back (`pop`) action reads from JSON without `destinationId`,
+  which it has no use for. It is still written, as `''`, for readers that
+  require it.
 - `SignatureNode` (`signature`): a box to sign in. Its `value` is a list of
   strokes, each a list of `[x, y]` points normalized to the box; `inkColor`,
   `strokeWidth` and `readOnly` are in `SignatureProperties`.

lib/src/api/models/action/navigation_action.dart

@@ -32,13 +32,18 @@ enum NavigationType {
   }
 }
 
+Object? _readDestinationId(Map json, String key) => json[key] ?? '';
+
 /// An action that navigates to a new page.
 @JsonSerializable()
 class NavigationAction extends ActionModel with Equatable, SerializableMixin {
   /// Defines how the navigation should be performed.
   final NavigationType navigationType;
 
-  /// Destination canvas node's ID.
+  /// Destination canvas node's ID. Empty for [NavigationType.pop], which
+  /// has no destination, and still written so older readers, which require
+  /// it, can read the action.
+  @JsonKey(readValue: _readDestinationId)
   final String destinationId;
 
   /// Parameters to pass to the destination page.

lib/src/api/models/action/navigation_action.g.dart

@@ -0,0 +1,15 @@
+import 'package:codelessly_api/codelessly_api.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('a navigate back action reads without a destination', () {
+    final action = NavigationAction.fromJson({
+      'type': 'navigation',
+      'navigationType': 'pop',
+    });
+    expect(action.navigationType, NavigationType.pop);
+    expect(action.destinationId, '');
+    // Still written, for readers that require it.
+    expect(action.toJson()['destinationId'], '');
+  });
+}