diff --git a/backend/alembic/versions/018_modify_chat.py b/backend/alembic/versions/018_modify_chat.py
new file mode 100644
index 0000000..24b6f98
--- /dev/null
+++ b/backend/alembic/versions/018_modify_chat.py
@@ -0,0 +1,80 @@
+"""018_modify_chat
+
+Revision ID: 863105882eba
+Revises: a0ba8268868d
+Create Date: 2025-06-30 16:44:17.123791
+
+"""
+from alembic import op
+import sqlalchemy as sa
+import sqlmodel.sql.sqltypes
+from sqlalchemy.dialects import postgresql
+
+# revision identifiers, used by Alembic.
+revision = '863105882eba'
+down_revision = 'a0ba8268868d'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.alter_column('chat', 'id',
+               existing_type=sa.INTEGER(),
+               type_=sa.BigInteger(),
+               existing_nullable=False,
+               autoincrement=True
+               )
+    op.alter_column('chat', 'datasource',
+               existing_type=sa.INTEGER(),
+               type_=sa.BigInteger(),
+               existing_nullable=True)
+    op.alter_column('chat_record', 'id',
+               existing_type=sa.INTEGER(),
+               type_=sa.BigInteger(),
+               existing_nullable=False,
+               autoincrement=True)
+    op.alter_column('chat_record', 'chat_id',
+               existing_type=sa.INTEGER(),
+               type_=sa.BigInteger(),
+               existing_nullable=False)
+    op.alter_column('chat_record', 'ai_modal_id',
+               existing_type=sa.INTEGER(),
+               type_=sa.BigInteger(),
+               existing_nullable=True)
+    op.alter_column('chat_record', 'datasource',
+               existing_type=sa.INTEGER(),
+               type_=sa.BigInteger(),
+               existing_nullable=True)
+    # ### end Alembic commands ###
+
+
+def downgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.alter_column('chat_record', 'datasource',
+               existing_type=sa.BigInteger(),
+               type_=sa.INTEGER(),
+               existing_nullable=True)
+    op.alter_column('chat_record', 'ai_modal_id',
+               existing_type=sa.BigInteger(),
+               type_=sa.INTEGER(),
+               existing_nullable=True)
+    op.alter_column('chat_record', 'chat_id',
+               existing_type=sa.BigInteger(),
+               type_=sa.INTEGER(),
+               existing_nullable=False)
+    op.alter_column('chat_record', 'id',
+               existing_type=sa.BigInteger(),
+               type_=sa.INTEGER(),
+               existing_nullable=False,
+               autoincrement=True)
+    op.alter_column('chat', 'datasource',
+               existing_type=sa.BigInteger(),
+               type_=sa.INTEGER(),
+               existing_nullable=True)
+    op.alter_column('chat', 'id',
+               existing_type=sa.BigInteger(),
+               type_=sa.INTEGER(),
+               existing_nullable=False,
+               autoincrement=True)
+    # ### end Alembic commands ###