Every building is one module of this repository. Height is measured, drawn as countable bands, and the top bar names what it is measuring. Wires are real call sites — the panel cites the line for each.
Press Height to change what height means. Fan-in asks what breaks if you change a module. Size is line count, which is volume and not importance. Tests and API surface are the other two. Same city, different truths.
Position is not measured. Two buildings are neighbours because of the layout, not because they are related — only the wires carry that.
A trace is one path through the system, stepped a hop at a time. Each hop is labelled call (both sites cited), entry (a route, command or handler), or async gap — the two sides never call each other and meet through shared state. A gap is where a reconstruction is doing the work, so it is marked rather than smoothed over.
The Limits tab lists what this could not determine. Wires are a lower bound: dynamic dispatch, dependency injection, event buses and cross-process calls leave little textual trace, so a missing wire is not evidence that no call exists.