Branched session files preserve entry ids, so leaf-id equality alone let a stale /btw answer promote into a different loaded session. Capture the originating session id at /btw start and require it to match at both the controller gate and every branchFromBtw checkpoint.
Fixes#7474
- Passed the authorized leaf through the branch executor and revalidated it before rewriting history.
- Refused promotion during active turns and bounded post-prompt drains.
- Consumed unavailable branch keys while showing pending and refusal state in the panel.
Fixes#7474
- Fixed session history desynchronization during `rewind` by performing a full context rebuild after applying branch changes.
- Prevented `rewind` tool output and assistant side-channel data from polluting the prompt cache by flushing and sanitizing session state.
- Added explicit test coverage for context reconstruction and assistant message sanitization after rewind events.
roboomp