Close any open stage (e.g. at load end) and freeze its line. When an end point is given, the stage is extended to it first (a stage ends when the next begins, or when the load finishes).
OptionalatElapsedMs: numberElapsed ms to extend the stage to before freezing.
OptionalatMemoryMb: numberHeap MB to extend the stage to before freezing.
The closed stage's line, if one was open.
Feed one progress event; returns the finished stage's line when this event closed a stage (so callers can mirror it to a console/log once).
The progress event.
The line for a just-finished stage, if any.
Record the model line (from header info) — kept with the report.
The model header info.
The formatted model line.
Accumulates progress events into the normalized text report: a live current-stage line while a stage runs, a frozen line per finished stage, and a separate before/after Total line.
Stage transitions are inferred from the event stream (a new label closes the previous stage), so the same accumulator works for conway's phases and Share's format-agnostic stages (download/parse/convert/...).