Save groups as reusable module presets

1. Open Modules beside Parts and Assembly in the left sidebar. Four starter modules include a power/control core, differential-drive base, pan/tilt vision module and arm mechanism. Review their connection notes before insertion.
2. Choose Add module. The app inserts fresh instances with their internal wires and mounts, adds a new group, stages it on clear ground and frames it. Your controller code, AI settings and existing project remain intact.
3. Create or edit a group, then use Group options → Save as module preset. Give it a name and wiring notes. Right-click Save assembly as module captures a part and its mounted descendants instead.
4. The module contains selected parts and wires wholly inside that selection. External wire endpoints are excluded and external mounts are detached. The save dialog states these limits.
5. Rename a saved module or update its notes with Edit saved module. Insert it repeatedly; group instance names and all part/wire IDs stay distinct. Existing servo code needs the new inserted IDs, visible in Inspector or Copy component ID.
6. Export a .robot-module.json file for backup, then use Import module JSON on another browser or device. Remove saved modules with the trash button; Undo module removal restores the last removed entry. Project Undo handles insertion or deletion of instances.

Import validates JSON without executing it. Limits are 1 MB and 1–100 parts per module, 32 saved modules and a 4 MB library guard, with the usual 200-part/64-group/1,200-wire project limits. If browser storage fails, export the session copy. Geometry-only parts remain geometry-only; insertion does not add chip firmware, gear physics, torque dynamics, grasping or walking balance.