- Fix turnState hierarchy corruption when SubTurns recursively call runAgentLoop
by checking context for existing turnState before creating new root
- Fix deadlock risk in deliverSubTurnResult by separating lock and channel operations
- Fix session rollback race in HardAbort by calling Finish() before rollback
- Fix resource leak by closing pendingResults channel in Finish() with panic recovery
- Add thread-safety documentation for childTurnIDs and isFinished fields
- Move globalTurnCounter to AgentLoop.subTurnCounter to prevent ID conflicts
- Improve semaphore acquisition to ensure release even on early validation failures
- Document design choice: ephemeral sessions start empty for complete isolation
- Add 5 new tests: hierarchy, deadlock, order, channel close, and semaphore