Keep a followed hook's work out of a session homed elsewhere
Commit

- A hook that followed its agent into a worktree whose session could not be re-homed (the home holds a step) wrote that tree's files onto the home's shadow branch and moved its base to this tree's HEAD. Steps, turn-start attribution and shadow migration now run only where the session is homed.
- post-todo looks for the active task baseline in every tree the session's baselines can be in, and only takes this session's: pre-task records its session, and runs in the parent agent's tree.
- A stamped reservation, with nothing written under it, no longer counts as an interrupted condensation.
Co-Authored-By: Claude Opus 5.5 (1M context) noreply@anthropic.com Entire-Checkpoint: 01M3WKP41865TT7ANGWCSP4M7Y
Checkpoints
Checkpoint 1