Worked on the openclaw/openclaw repository to deliver a targeted backend bug fix that improved multi-agent session reliability. Addressed an issue in the sessions_spawn flow where sub-agent model selection failed to honor per-sub-agent overrides, causing unintended inheritance from parent agents. By leveraging TypeScript and focusing on API development and bug fixing, the solution incorporated the allowAny flag from buildAllowedModelSet() to ensure each sub-agent could operate with its own specified model. This change reduced misconfiguration risks and enhanced scalability for diverse modeling requirements, strengthening model isolation and correctness across environments without introducing new features during the development period.