diff --git a/app/api/database.py b/app/api/database.py
index 501f19b2..b543aa04 100644
--- a/app/api/database.py
+++ b/app/api/database.py
@@ -162,8 +162,9 @@ async def execute_migration(body: MigrateRequest, request: Request) -> dict:
 
     result = migrate_data(body.source_url, body.target_url)
     if not result["success"]:
+        error_summary = "; ".join(result.get("errors", ["Unknown error"]))
         raise HTTPException(
             status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
-            detail={"message": "Migration completed with errors", **result},
+            detail=f"Migration completed with errors: {error_summary}",
         )
     return result
diff --git a/app/utils/db_migrate.py b/app/utils/db_migrate.py
index 815b7cef..f95d97f0 100644
--- a/app/utils/db_migrate.py
+++ b/app/utils/db_migrate.py
@@ -82,6 +82,7 @@ def preview_migration(source_url: str) -> dict[str, Any]:
         total = 0
         with src_engine.connect() as conn:
             for table_name in tables:
+                # table_name is safe — sourced from inspect().get_table_names(), not user input
                 row = conn.execute(text(f'SELECT COUNT(*) FROM "{table_name}"')).fetchone()  # noqa: S608
                 count = row[0] if row else 0
                 result.append({"name": table_name, "row_count": count})
@@ -182,6 +183,8 @@ def migrate_data(
                 total_for_table = len(rows)
                 for i in range(0, total_for_table, batch_size):
                     batch = rows[i : i + batch_size]
+                    # strict=False: column count should always match, but tolerate
+                    # minor schema drift (e.g. extra columns) to avoid crashing mid-migration.
                     insert_data = [dict(zip(column_names, row, strict=False)) for row in batch]
                     tgt_session.execute(tgt_table.insert(), insert_data)
                     tgt_session.commit()
diff --git a/frontend/templates/db_wizard.html b/frontend/templates/db_wizard.html
index ba13ec07..6035f3dd 100644
--- a/frontend/templates/db_wizard.html
+++ b/frontend/templates/db_wizard.html
@@ -411,7 +411,7 @@
 
           {# Migration progress / result #}
           <div x-show="migrateLoading" class="mt-4" role="status" aria-live="polite">
-            <div class="w-full bg-gray-200 rounded-full h-3">
+            <div class="w-full bg-gray-200 rounded-full h-3" role="progressbar" aria-label="Migration in progress" aria-valuetext="Migrating data">
               <div class="bg-indigo-600 h-3 rounded-full animate-pulse-bar" style="width:100%"></div>
             </div>
             <p class="text-sm text-gray-600 mt-2">Migration in progress — please do not close this page…</p>
diff --git a/tests/test_db_wizard_api.py b/tests/test_db_wizard_api.py
index 37437a11..8558d4a7 100644
--- a/tests/test_db_wizard_api.py
+++ b/tests/test_db_wizard_api.py
@@ -31,7 +31,7 @@ class TestDatabaseApiEndpoints:
     def test_build_url_sqlite(self, client):
         """Test building a SQLite URL as admin."""
         # Simulate admin session
-        with client.session_transaction() if hasattr(client, "session_transaction") else _noop():
+        with client.session_transaction() if hasattr(client, "session_transaction") else _NoOpContextManager():
             pass
         # Use the session cookie approach
         client.cookies.set("session", "test")
@@ -148,7 +148,9 @@ class TestDatabaseWizardView:
 
 
 # Context manager helper for tests that don't need session_transaction
-class _noop:
+class _NoOpContextManager:
+    """Dummy context manager for tests that don't need session_transaction."""
+
     def __enter__(self):
         return None