Handoff

A new session can take over a loop by the book’s id, and what the units proved and what the notice asked carry over.

sequenceDiagram
  participant A as Session A (leaving)
  participant F as Book files
  participant B as Session B (taking over)
  A->>A: anchorloop_stage read shows the book: id
  A->>B: handoff note carries the id
  B->>F: kind with resume: id, before any evidence
  F-->>B: the book moves to B's path
  F-->>A: marker at A's path: moved, to B
  B->>B: continues, units' evidence carried over
  A->>A: next call: told B resumed it

The id, the refusals, and what the old session sees

A handoff names the open book by the id on the book: line of read. The new session adopts it with resume: <book id> on its first kind, or with the first todo’s metadata.resume. What its units proved and what the notice asked carry over; its todos are the new session’s, created before or after resume, and the old session’s todos are retired, so a child reading the adopted book binds by ticket to the new session’s unit.

An unknown, closed, subagent’s, or other project’s id is refused with the reason. A session on the same ticket that passes no id keeps its own book. The session that left the book is told which session resumed it on its next tool result, whichever tool it is, and records nothing in the moved book.