ChatHistory behavior changes from v2 to v3?

[jeff87218]

Hello,

I’d like to ask whether there were any behavioral or structural changes to ChatHistory between v2 and v3.

In v2, I had my own custom implementation of ChatHistory, and everything worked fine, including:
tool calling
deleting / clearing chat history
general message handling

After upgrading to v3, the same implementation consistently throws the following exception:
ChatHistoryException: 'No messages in the chat history. It may have been filled with too large a message.'

I noticed that ToolCallResultMessage has been renamed to ToolResultMessage, and I have already updated my code accordingly. However, the exception still occurs.

To clarify, this issue did not occur in v2 at all — the same logic and flow worked correctly before the upgrade.

So I’d like to ask:

Were there any breaking or behavioral changes to ChatHistory in v3?

Are there any new constraints or required behaviors when implementing a custom ChatHistory in v3?

Is there anything in v3 that could cause the chat history to be considered “empty” even though messages were successfully added (and worked in v2)?

Any guidance or migration notes would be greatly appreciated.

Thank you very much!

[ilvalerione]

The Chat History was touched very little. Also unit tests didn't changed. I need to have more context about your implementation to understand the detail that is causing this issue in your code, in particular the implementation of onNewMessage and setMessages methods

[jeff87218]

After further investigation, I found that this issue does not seem to be caused by my custom ChatHistory implementation.
It appears that the behavior of RAG QueryPreProcessed has changed in v3.

In v3, QueryPreProcessed executes the following logic:

$query = $state->getChatHistory()->getLastMessage();

However, during QueryPreProcessed, the current message can be the very first message in the conversation, meaning the chat history may not contain any prior messages yet.
In this case, calling getLastMessage() results in the ChatHistoryException being thrown.

[ilvalerione]

It's fixed in the latest commit. You should get the latest version with a composer update.

Thank you for pointing it out.

[jeff87218]

Awesome, thank you for fixing it so quickly.
I’ll update to the latest version and test it.