[Bug]: Error when using ChatMemoryBuffer and Context Serialization in llama_index Workflow

[Sanbornzhang]

Bug Description

I am trying to use ChatMemoryBuffer in a llama_index workflow, along with Context serialization to save and restore intermediate states. However, when calling Context.from_dict, I encounter the following error:

TypeError: Can't instantiate abstract class BaseChatStore with abstract methods add_message, delete_last_message, delete_message, delete_messages, get_keys, get_messages, set_messages

The error occurs in line 193 of llama_index/core/workflow/context.py, specifically in this code segment:

serializer.deserialize(ev) for ev in data["broker_log"]

Version

0.12.30

Steps to Reproduce

The error occurs because when global_ctx is passed to Context.from_dict while using ChatMemoryBuffer, the BaseChatStore abstract class methods (such as add_message, delete_message, etc.) are not properly implemented or instantiated in the global_ctx.

Relevant Logs/Tracbacks

[logan-markewich]

@Sanbornzhang you'll have to provide some full code to reproduce this issue. Not every object is easily serializable either, you may have to use pydantics field serializer utils to define how to serialize and load specific event objects