- Introduced `--downshift-boomerang` CLI flag and `downshift.boomerang` configuration setting.
- Integrated boomerang validation hand-back logic and context cutting within the agent session.
- Added system prompt templates and runtime checks to facilitate message handling for boomerang transitions.
- Included unit tests to verify context management and validation pass requirements during the boomerang process.
- Included the todo tool in downshift action triggers, gated on the plan nudge being in context — a post-nudge todo init is the planning-complete signal, while a turn-one todo remains bookkeeping.
- Updated flag help, settings schema, SDK docs, slash-command text, and plan-nudge instructions.
- Added a regression test covering the nudge-gated todo trigger.
- Added comprehensive tests for downshifting model behavior, including plan nudge injection and completion safety mechanisms.
- Verified session persistence accuracy by validating that from-disk rebuilds match the live agent state.
- Confirmed correct cache key propagation during tan commands to ensure provider caching is preserved.
- Removed obsolete reasoning slide tests.