Instructions:
1. Each entity has a name and a direction (source = into inverter, sink = out of inverter, both = bidirectional).
2. Use + Add to add an entity, × to delete one, and + segment for multi-part paths (like Home).
3. Click "Draw" on a segment or label, then click on the image to add points (first point = start).
4. Hold Shift to snap to horizontal/vertical lines. Esc or End to stop.
5. The derived route key(s) are shown under each entity; fix any red errors before exporting.

Path Direction:
Draw FROM source TO destination. The pulse animates first point → last point (green = start, red = end).
Open this tool from the repo root so it can load nodes/topology.js.