Delete soft-deleted conversations before dropping is_deleted column

Use sa.table() with sa.delete() and sa.true() to generate cross-database
compatible SQL that works in both online and offline modes without
requiring schema reflection.

api/migrations/versions/2025_09_02_2012-4f02b6704509_remove_unused_is_deleted_field_from_.py

@@ -1,33 +0,0 @@
-"""remove unused is_deleted field from conversations
-
-Revision ID: 4f02b6704509
-Revises: 7bb281b7a422
-Create Date: 2025-09-02 20:12:37.311318
-
-This migration runs on both PostgreSQL and MySQL.
-"""
-from alembic import op
-import models as models
-import sqlalchemy as sa
-
-
-# revision identifiers, used by Alembic.
-revision = '4f02b6704509'
-down_revision = '7bb281b7a422'
-branch_labels = None
-depends_on = None
-
-def upgrade():
-    # ### commands auto generated by Alembic - please adjust! ###
-    with op.batch_alter_table('conversations', schema=None) as batch_op:
-        batch_op.drop_column('is_deleted')
-
-    # ### end Alembic commands ###
-
-
-def downgrade():
-    # ### commands auto generated by Alembic - please adjust! ###
-    with op.batch_alter_table('conversations', schema=None) as batch_op:
-        batch_op.add_column(sa.Column('is_deleted', sa.BOOLEAN(), server_default=sa.text('false'), autoincrement=False, nullable=False))
-
-    # ### end Alembic commands ###

api/migrations/versions/2025_11_27_1827-e5d7a95e676f_remove_unused_is_deleted_from_.py

@@ -0,0 +1,29 @@
+"""remove unused is_deleted from conversations
+
+Revision ID: e5d7a95e676f
+Revises: 7bb281b7a422
+Create Date: 2025-11-27 18:27:09.006691
+
+"""
+import sqlalchemy as sa
+from alembic import op
+
+revision = "e5d7a95e676f"
+down_revision = "7bb281b7a422"
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    conversations = sa.table("conversations", sa.column("is_deleted", sa.Boolean))
+    op.execute(sa.delete(conversations).where(conversations.c.is_deleted == sa.true()))
+
+    with op.batch_alter_table("conversations", schema=None) as batch_op:
+        batch_op.drop_column("is_deleted")
+
+
+def downgrade():
+    with op.batch_alter_table("conversations", schema=None) as batch_op:
+        batch_op.add_column(
+            sa.Column("is_deleted", sa.BOOLEAN(), server_default=sa.text("false"), autoincrement=False, nullable=False)
+        )