export_session() reads through get_messages(), so before the read fix an
already-serialized string went straight back into _insert_message_rows() and
got re-dumped — an export/import round trip permanently corrupted the row.
Guard the three write paths the same way tool_calls already is: parse a
string argument before storing it, and drop metadata that isn't an object
rather than persisting something no reader can use.
Co-authored-by: xxxigm <xxxigm@users.noreply.github.com>
Co-authored-by: aml1973 <aml1973@users.noreply.github.com>
Brooklyn Nicholson
19dc35cf57