## What changed
- Add experimental `beforeTurnId` support to `thread/fork` for copying history strictly before a turn, including an in-progress turn.
- Use before-turn forks for TUI backtracking and safety retries so the replacement prompt retains thread context instead of recreating the branch from the preceding turn or a new thread.
- Add experimental `deferGoalContinuation` support so safety-retry forks can inherit an active goal while waiting for the replacement turn before automatic continuation resumes.
- Hide duplicated nested-review prompts when replaying history or selecting a prompt to edit.
## Testing
- Cover before-turn truncation, fork validation, active-goal inheritance, TUI safety retries, backtracking, and nested-review replay.
GitOrigin-RevId: 4915d85ae1929a0b8c40f3ed7dca29c7a5bdcdf3
