AI PCB agents become useful when their output can be rejected by something other than another model. Copperhead 0.12 adds a grounded design-review command and tightens the gates around its KiCad workflow. The release rejects footprints whose pads do not map to symbol pins, cuts replies that invent tool results, and refuses to finish a stage without written quality evidence.
Those checks change the agent's job from generating a plausible board to producing an artifact that survives deterministic review. Copperhead already edits real KiCad files and runs ERC and DRC. The new release makes failure handling more explicit: only failed repairs consume the repair budget, placement gets a search step, and review findings feed back into the draft instead of disappearing into a transcript. The constraint being removed is not schematic capture time. It is the engineer's need to manually discover which parts of an agent run were never grounded in the design database.
PCB teams evaluating design agents should score them on how often bad work is stopped before a stage transition, not how quickly a demo reaches a rendered board. Vendors that cannot expose machine-checkable intermediate state will lose to tools that make every handoff a test gate.