CANCELLED

Stopped by IndexBuild.cancel or by the catalog closing.

Not a failure, and not a state anything has to repair. A cancelled build leaves an index that is defined and partially covered, which is exactly what a crashed build leaves and exactly what a build still running looks like from outside — and every query already handles it by scanning the segments the index does not cover. That is why cancellation needed no rollback: there is nothing to roll back to that is not already a state the engine lives in.