Build a simulation of `top` from `design`, sized for `arraySize` cycles - or keep the one already built if it is of the same thing. The implementation KEEPS `design`. Instance enumeration is answered from it, which is what lets the renderer stop building a simulation of its own: which instances exist is a design-time fact, and only widths and data need the elaborated one.

Bumped by every Build. Anything cached or in flight carries the epoch it belongs to, so an answer from a superseded build is discarded rather than shown.

Turn stable signal names into this build's read handles, with each signal's width. A signal named on an INPUT port resolves to the handle of the OUTPUT driving it: a net has one driver, and it is the driver that has data. Doing that here rather than in the caller is what lets a remote simulator answer at all, since the mapping needs the elaborated simulation.

The instances of `sheet` directly inside `parent`. Answered from the design, so it costs one pass over a sheet's own components however many times that sheet is instantiated.

The ports of one canvas component, and how many elaborated copies the simulation holds - the question the schematic's right-click menu asks.

The ports of several instances at once, because the selector draws a whole collapsed hierarchy and one round trip for it is the difference between a pause and a stutter.

One signal at one cycle - a hover tooltip, or the schematic probe.

Everything the step panel shows at one cycle, in one request.

The samples the current view draws, for these signals, plus the cursor column - which is separate because the drawn window samples every `Multiplier` cycles while the cursor sits on an exact one.

Drop the simulation and whatever it holds.

Advance towards `cycle`, in chunks, reporting the clock reached after each so that a progress bar can move and a Cancel can be answered.