The parts library

The engine will only build from parts it knows: seventeen definitions in a curated library, each with a HUMAN-VERIFIED pin map. Sixteen are yours to add; the seventeenth, pico2w_socket, is the MCU itself — always present, never a peripheral. This is a deliberate wall. An AI can help you fill in a spec, but it cannot invent a part, because invented parts come with invented pinouts, and an invented pinout becomes a real short circuit at the bench.

Ask for something outside the library and the validator answers before the generator ever runs. Three refusals, one per failure mode:

X1: no part specified — every peripheral needs a part from the parts library
U9: unknown part "oled_ssd1306" — not in the parts library
U8: pico2w_socket is not a peripheral part — it cannot be added to the peripherals list

The second message is the one a typo earns you. Before this validator existed, a misspelled part was SILENTLY DROPPED — the board rendered "successfully" with the component missing, which is the worst kind of success. Now the spec never reaches the generator until every part name resolves.

Each part also declares extra fields it REQUIRES — the fixed entries in its palette definition. Forget one and the V7 message names both the component and the field. The pin is different: nothing in the validator demands it, but the generator cannot wire a trace to a pin that is not there, so a missing pin fails later and louder, with a trace error instead of a sentence. And an LED's color is optional — the engine accepts its absence; it is documentation for the schematic.