Conservative Repair Scope

What the engine repairs, what it refuses, and why unsupported is a normal result.

What is repaired

The engine removes exact duplicate and degenerate faces where that is safe, fixes the orientation of a supported single shell, and retriangulates suitable exactly planar folded or overlapping patches using their existing oriented boundaries. It can optionally collapse short existing edges when you turn on Merge tiny existing edges.

Before a repair is offered, the result is written as binary STL, reloaded, and fully re-validated, and guards on shell count, bounds, and volume must pass.

What is refused

The engine does not automatically repair open or non-manifold meshes after exact cleanup, general non-coplanar self-intersections, invalid or branching patch boundaries, or multiple or nested shells. It does not fill arbitrary holes, smooth, voxelize, decimate, or weld nearby walls.

Unsupported is an expected outcome

When the engine cannot fix a mesh conservatively, the app reports Cannot repair safely and offers nothing to save. Guessing a solid would risk silently changing your model, so refusal is the correct behavior, not a bug. Likewise, a scan stopped by a limit or timeout is Check incomplete, never a clean pass.

Defaults

Weld tolerance is zero by default. The two supplied defective rail test models repair in default mode with their tiny-triangle warnings retained: intersections are removed, and the remaining warnings are still shown.