Folds naturalDelta — the movement leg's signed effect on the account's balance in minor
units (balanceDelta; a spend adds a negative delta) — into the account's pending total and
returns the post-add total. Atomic per account: two nodes adding concurrently both see a
total that includes at least their own delta.
Optionaloptions: CallOptionsStreams every counter row — what reconcileReservations (src/worker/orphans.ts) walks to
repair leaked pending against the journal-derived truth during quiesced maintenance.
Optionaloptions: CallOptionsThe account's current net pending total; 0n for an account with no row.
Optionaloptions: CallOptions
The shared cross-node reservation counter: one pending total per account, folded atomically.
addreturns the post-add total, so accept screens are add-then-check — a concurrent add on another node is either already in the returned total or arrives later and sees ours; totals only drift conservative (at-or-after our add). Fail-closed by construction: an unreachable counter throws, and the caller refuses the movement rather than accepting blind.