Add SQLite batch operations support for column type changes

- SQLite doesn't support ALTER COLUMN TYPE directly
- Use batch_alter_table for SQLite (creates temp table, copies data, renames)
- Keep direct ALTER COLUMN for PostgreSQL and MySQL
- Applies to both upgrade and downgrade operations
- Fixes: sqlalchemy.exc.OperationalError with SQLite

Author: crivetimihai

mcpgateway/alembic/versions/878e287d2366_resize_url_and_slug_columns_to_191.py

@@ -58,35 +58,73 @@ def upgrade() -> None:
         """)
 
     # Resize columns to String(191)
-    op.alter_column(
-        'gateways',
-        'slug',
-        existing_type=sa.String(length=255),
-        type_=sa.String(length=191),
-        existing_nullable=False
-    )
-    op.alter_column(
-        'gateways',
-        'url',
-        existing_type=sa.String(length=767),
-        type_=sa.String(length=191),
-        existing_nullable=False
-    )
+    # SQLite requires batch operations for ALTER COLUMN
+    if dialect_name == 'sqlite':
+        with op.batch_alter_table('gateways', schema=None) as batch_op:
+            batch_op.alter_column(
+                'slug',
+                existing_type=sa.String(length=255),
+                type_=sa.String(length=191),
+                existing_nullable=False
+            )
+            batch_op.alter_column(
+                'url',
+                existing_type=sa.String(length=767),
+                type_=sa.String(length=191),
+                existing_nullable=False
+            )
+    else:
+        # PostgreSQL and MySQL support direct ALTER COLUMN
+        op.alter_column(
+            'gateways',
+            'slug',
+            existing_type=sa.String(length=255),
+            type_=sa.String(length=191),
+            existing_nullable=False
+        )
+        op.alter_column(
+            'gateways',
+            'url',
+            existing_type=sa.String(length=767),
+            type_=sa.String(length=191),
+            existing_nullable=False
+        )
 
 
 def downgrade() -> None:
     """Downgrade schema."""
-    op.alter_column(
-        'gateways',
-        'slug',
-        existing_type=sa.String(length=191),
-        type_=sa.String(length=255),
-        existing_nullable=False
-    )
-    op.alter_column(
-        'gateways',
-        'url',
-        existing_type=sa.String(length=191),
-        type_=sa.String(length=767),
-        existing_nullable=False
-    )
+    # Get database dialect for dialect-specific operations
+    bind = op.get_bind()
+    dialect_name = bind.dialect.name
+
+    # SQLite requires batch operations for ALTER COLUMN
+    if dialect_name == 'sqlite':
+        with op.batch_alter_table('gateways', schema=None) as batch_op:
+            batch_op.alter_column(
+                'slug',
+                existing_type=sa.String(length=191),
+                type_=sa.String(length=255),
+                existing_nullable=False
+            )
+            batch_op.alter_column(
+                'url',
+                existing_type=sa.String(length=191),
+                type_=sa.String(length=767),
+                existing_nullable=False
+            )
+    else:
+        # PostgreSQL and MySQL support direct ALTER COLUMN
+        op.alter_column(
+            'gateways',
+            'slug',
+            existing_type=sa.String(length=191),
+            type_=sa.String(length=255),
+            existing_nullable=False
+        )
+        op.alter_column(
+            'gateways',
+            'url',
+            existing_type=sa.String(length=191),
+            type_=sa.String(length=767),
+            existing_nullable=False
+        )