A brand-new phenomenon, and a theory that held.

A metal powder-bed machine began producing a regular dimensional oscillation inside large, densely packed sections of a build: a repeating pattern of oversize and undersize nobody had seen before. It was in no known-issue list, and there was no theory on site that explained it. Genuinely novel, with nothing to search for.

Heat build-up in dense regions was understood in general. Small variations across the build area were understood in general. Neither, alone, produced this pattern, and nobody could say why the oscillation lived inside the dense sections specifically, or why some materials showed it far more strongly than others.

Cala proposed a coupling nobody on site had put together: in densely packed regions, accumulated heat locally changes how much of the delivered energy actually takes effect, and the strength of that coupling differs sharply between materials. That produces a self-modulating pattern that only appears where packing is dense, exactly where it was seen, at a strength that depends on the material, exactly as observed.

It did not stop at the mechanism. It laid out discriminating experiments: change the packing arrangement without changing the geometry, reorder the build sequence, repeat across materials, each arm with a prediction attached.

The experiments ran as designed. The oscillation moved with packing and sequence exactly as predicted, and its strength tracked the material exactly as predicted.

A phenomenon with no name and no write-up went from observation to confirmed mechanism, with a test plan attached. That is the case Cala is built for: not looking up what is known, but reasoning about what is not.