fix: avoid creating/initializing databases during user discovery

get_all_user_ids now checks if DB file exists before calling get_session_for_user. This prevents get_engine_for_user from triggering init_user_database and creating tables for stale workspace folders. Without this fix, a read-only ID scan creates/initializes SQLite databases and default tables as a side effect, which can silently create fresh DBs for stale workspace folders and hide missing/corrupt-database states that discovery previously surfaced.

backend/services/database.py

@@ -106,6 +106,13 @@ def get_all_user_ids() -> List[str]:
             canonical_user_id = workspace_id
             db = None
             try:
+                # Check if DB file exists before opening session to avoid creating/initializing DBs
+                db_path = get_user_db_path(workspace_id)
+                if not os.path.exists(db_path):
+                    # No DB file exists, use workspace ID as fallback
+                    canonical_user_id = workspace_id
+                else:
+                    # DB file exists, try to resolve canonical user_id from DB
                     db = get_session_for_user(workspace_id)
                     if db:
                         onboarding_row = (