Start operation n (0, 1, … — distinct inputs, so a superseded run and
its successor are distinguishable). Returns the operation's promise, or
nothing for a fire-and-forget operation.
Optionalsignal: AbortSignalHow many inner work items (fetches, decodes, replies) have been requested so far.
Settle the inner work item at index (request order). Called at most once per index.
JSON-comparable snapshot of what the operation committed.
OptionalinBookkeeping that must drain (in-flight map entries, busy slots, locks). Default 0.
OptionalfailuresFailures surfaced other than by rejecting start's promise (warnings, error events).
OptionalresetA mid-flight reset that keeps the owner usable (a dataset switch).
One live instance of the operation's owner, wired to controllable inner work.