Worked on the openclaw/openclaw repository to enhance backend reliability by introducing a validation guardrail for cron job handling. Focused on preventing invalid cross-agent main-session bindings, the solution rejects attempts to set sessionTarget to 'main' for non-default agents during cron job creation or patching. This approach, implemented using Node.js and TypeScript, ensures that only valid session bindings are permitted at write time. Comprehensive test coverage was added to safeguard against regressions, and changelog documentation was updated to clarify the impact for users. The work demonstrates attention to robust backend development and careful validation of session management logic.