- Exported `finalizeSubprocessOutput()` function and `SubmitResultItem` interface for subprocess output finalization with submit_result validation.
- Added automatic reminders (up to 3) when subagent stops without calling submit_result tool, aborting with exit code 1 after final reminder.
- Extracted subprocess output finalization logic into dedicated `finalizeSubprocessOutput()` function for improved testability and reusability.
- Added comprehensive test coverage for subagent warning injection, reminder behavior, and abort handling in executor module.