Sequence counters.
Runtime file sets keyed by id, with the owning window.
Jobs keyed by job id.
OptionalnextScripted outcome for the next pickFiles.
Every node keyed by content hash (seeded plus written).
Pins keyed by ref.
Mutable roots keyed by <pubkey>/<treeName>.
Auto-advance timers keyed by job id.
In-memory state of the hashtree mock.
Example