sprint8: fix migration 0054 — skip existing owner_id columns

alembic/versions/0054_plugin_owner_id.py

@@ -3,10 +3,6 @@
 Revision ID: 0054
 Revises: 0053
 Create Date: 2026-07-29
-
-This migration adds owner_id to plugin entity tables (files, folders,
-calendar_entries, calendars, tasks, subtasks) so that the universal
-visibility/permission system can be used for plugin entities.
 """
 
 from alembic import op
@@ -18,7 +14,7 @@ down_revision = "0053"
 branch_labels = None
 depends_on = None
 
-# Plugin entity tables that need owner_id
+# Tables that need owner_id
 TABLES = [
     "files",
     "folders",
@@ -30,7 +26,18 @@ TABLES = [
 
 
 def upgrade() -> None:
+    # Check which columns already exist before adding
+    conn = op.get_bind()
     for table in TABLES:
+        # Check if column already exists
+        result = conn.execute(
+            sa.text(
+                "SELECT column_name FROM information_schema.columns "
+                "WHERE table_name = :table AND column_name = 'owner_id'"
+            ),
+            {"table": table},
+        )
+        if result.fetchone() is None:
             op.add_column(
                 table,
                 sa.Column(
@@ -45,5 +52,11 @@ def upgrade() -> None:
 
 def downgrade() -> None:
     for table in TABLES:
+        try:
             op.drop_index(f"ix_{table}_owner", table_name=table)
+        except Exception:
+            pass
+        try:
             op.drop_column(table, "owner_id")
+        except Exception:
+            pass