Missing JSON deserialization in SQLAlchemy data layer when using SQLite

[petri]

Describe the bug

When using the SQLAlchemy data layer with SQLite, in get_all_user_threads(), the returned metadata seems to be a JSON string but it is not ever deserialized.

chainlit/backend/chainlit/data/sql_alchemy.py

Line 623 in 8e739b3

metadata=thread["thread_metadata"],

For me, backend/chainlit/socket.py, line 53 in resume_thread() subsequently fails attempting metadata.copy() triggered by having an implementation of @on_chat_resume.

Interestingly, similar case seems to be correctly handled elsewhere in the same module:

chainlit/backend/chainlit/data/sql_alchemy.py

Lines 126 to 129 in 8e739b3

	# SQLite returns JSON as string, we most convert it. (#1137)
	metadata = user_data.get("metadata", {})
	if isinstance(metadata, str):
	metadata = json.loads(metadata)

Given that, I'd go as far as to suggest the whole module should be reviewed; there might be other places where deserialization is missing.

To Reproduce

Try out anything that uses the metadata using SQLAlchemy + SQLite. I tried on_chat_resume which appears to trigger the problematic code.

For what it's worth, I thought SQLAlchemy handled this kind of differences transparently, unless it is being used in a low-level way... ?

[petri]

Re other places possibly needing a fix, line 652 has this ... no idea if it needs fixing or not.

metadata=(
    step_feedback["step_metadata"]
    if step_feedback.get("step_metadata") is not None
    else {}
),