How to avoid DroppableDisposedException?

[sdtnjung]

Hi! I have to admit that I have zero Flutter/Dart experience but using an AI agent still allows me to iterate quickly and get great results.

DroppableDisposedException: Try to use 'RustArc<dynamic> after it has been disposed

So my agent built a Dart service which I thought is a proper workaround for this issue but still my struct got disposed.

Could you point me in the right direction for keeping my session struct in place across view transitions?

[fzyzcjy]

Hi, without any code it is hard to guess what happens... Could you please show a bit more?

[sdtnjung]

Yes, sure.

Pattern that triggers error:

  class MyWidget extends StatefulWidget {
    String? sessionId;
    SomeRustObject? rustObject;

    Future<void> handleAuth() async {
      rustObject = createRustObject();

      final result = await someRustFunction();

      switch (result) {
        case ResultType_RequiresDialog(:final challenge):
          // Extract data from challenge
          final data = extractData(challenge: challenge);

          // Async operation - widget may rebuild
          final userInput = await showDialog<String>(...);

          // ERROR: RustArc disposed during async operation
          await continueWithRustObject(rustObject: rustObject!);
      }
    }
  }

Root cause: RustArc objects stored as widget state get disposed during async
operations (dialogs, network calls) that may trigger widget rebuilds.

Current workaround: Extract all data from RustArc objects immediately and work with
primitives:

 // Extract everything immediately
 String extractedData = extractData(challenge: challenge);
 // Never access 'challenge' again

 await showDialog(...);
 // Use extractedData instead of RustArc objects

Questions:

1. Should RustArc objects be avoided as Flutter widget state?
2. Is there a recommended pattern for managing opaque objects across async
   boundaries?
3. Could FRB provide better lifecycle management for Flutter widgets?

The workaround works but feels like fighting the framework. Any architectural
guidance would be appreciated!

[fzyzcjy]

without more code, I guess maybe use fn f(a: &SomeType) instead of fn f(a: SomeType) if you do not want the SomeType obj be disposed. This is not specific to frb, but a general rust rule