Google Antigravity

@@ -8,6 +8,17 @@ We asked Google Antigravity, running Gemini 4 Argon inside Adom Hydrogen, to des  Clips 6 to 13, stitched. Argon placed and routed its own 12 V to 5 V buck live in KiCad, fixed a real current hotspot and a hot inductor with copper, labelled the board and passed every check on the finish line: 35 A/mm² peak against a 60 A/mm² limit, 26 °C rise against a 50 °C budget, 38 silkscreen labels, real 3D parts, and Gerbers, drill, BOM and placement checked against the board. Each shortcut it tried on the way was caught and sent back; the one budget it moved, the switch-node length (12 to 24 mm), stays on the record. Captions are in [argon-run2-ai-pcb.srt](videos/argon-run2-ai-pcb.srt) and [.vtt](videos/argon-run2-ai-pcb.vtt). +## The honest verdict on run 2: a clean layout of a circuit that needs a revision++After the run we asked Argon, in the same conversation and without hints, whether it had validated the capacitance a real buck converter needs. Its answer: "as a real hardware engineer, I would not send this board to fab as-is without changes." Our own review agreed.++- **Input capacitance.** Two 10 µF / 25 V 0805 ceramics keep only about 2.5 to 3.5 µF each at 12 V, half of what the design calculation assumed, and there is no damped bulk capacitor. Plugged live into a 16 V supply through ordinary leads, the input can ring toward 30 V, past the regulator's rating.+- **Output capacitance and loop stability.** Three 22 µF / 10 V 0805 X5R parts are worth about 21 to 25 µF at 5 V, not the 36 µF assumed. With the 68 pF feedforward capacitor, the loop crossover would pass TI's 40 kHz ceiling for this internally compensated part.+- **Inductor.** The design's own calculation gives a 22.9 µH minimum; the board uses 15 µH. It was never resolved.+- **Bootstrap loop.** The bootstrap capacitor's return trace is 14.7 mm on the switch node; the switch-node length budget was raised from 12 to 24 mm instead of moving the part.++Argon knew all of this when asked, and found the loop-stability issue before we did, but did not apply it while building. The layout checks (current density, heat, silkscreen, 3D, manufacturing files) were real and passed; none of them looks at whether the circuit's capacitance and compensation are right. Revision 2 follows: Argon applies its own review.+ ## Run 1 in 2:41: it looked finished, but it was not  ::adom-video{src="/adom/antigravity/render/first-ai-pcb/videos/first-argon-ai-pcb.video.json"}