4 commits, squashed; the originals stay reachable from tag archive/merge-main-develop. -8b9e0e0c0jyviko: Continuity rig: an opened tube end capped G1 and G2, as cases -24a58066cjyviko: Sweeps rig: a circle touching its axis revolved a quarter turn, as a case -51316b7ecjyviko: Import rig: the horn torus quarter written to STEP and read back, as a case -8524458cejyviko: Tests skill: when a check is a unit test and when it is a rig case Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01DtL5M41G8Nua7HvuFPZkmJ