- Implement dynamic regex matching fallback (re.search) in `node.test` with safe handling of invalid patterns.
- Refactor terminal window resizing (setwinsize) to trigger only on non-router devices and handle SIGWINCH re-renders.
- Introduce `contextvars` context copying for background worker threads in gRPC execution and AI servicers.
- Add unit tests for regex validation, malformed expression fallbacks, and variable formatting in node testing.
- Optimize Playbook Builder AI guidelines for single-task test evaluations.
- Unify codebase comments to English.