How the vision quality loop inspects and refines your design

Every HIIE Engine generation runs through a vision quality loop so the part you get back has actually been looked at — not just produced and handed over blindly.

What the loop does

For each generation the engine follows these stages:

1. Generate the part on the build123d engine.
2. Structural geometry gate — check that the output is a real, valid part (not degenerate geometry).
3. Render snapshots of the part.
4. Vision review — Camelia visually inspects what the part actually looks like in those snapshots.
5. Auto-refine based on what the review found, then loop again.

The loop keeps the best-scoring pass and archives that one.

How many passes you get

The number of refinement passes depends on what you're doing:

• A fresh prompt gets up to 3 passes.
• A Refine (an iteration on an existing design) gets a 2-pass budget.

Why it matters

This loop is the reason the HIIE Engine is the default, preferred CAD path: it produces real B-rep STEP, STL, and GLB outputs and visually verifies them before archiving, all for free with no monthly cap. The vision review scores passes on a 0–10 scale internally — you don't need to manage any of this; the engine simply returns the strongest result it found within the pass budget.