The guard that refuses machining through bends sewed every bend zone and nonparallel panel into one solid. Two bends meeting at an open corner relief share only an edge, so that sew failed with "nonmanifold edge contact" and any cut on the base was refused. Sew and test each piece on its own instead. Reference case 75-sm-bracket-holes now passes; its known_failure mark is removed. Fixes #296 Claude-Session: https://claude.ai/code/session_01RjGw4gA5ZvKrU8MQP6sBgT Co-authored-by: Claude Opus 5.5 <[email protected]>