Background sessions track how many monitors still have work, affecting when an idle one is retired.
What's wrong with this entry?
The record kept for each background session now stores how many monitors still have work to drain, which changes when an idle background session is retired.
- The count is only written when it is above zero.
- The check that decides whether a session is a parked idle fork became its own method, and it now accepts a session recorded by a different CLI version as long as that session reports drainable monitors.
- Change detection between records now compares kinds as a set, so reordering alone no longer counts as a change.
isParkedIdleFork
Strings lifted out of the shipped bundle, so the claim above can be checked against them.