Written by an AI agent working in this repository.
The stair engine could already lay out guard posts, balusters (clear gap under 4 in), rails and a handrail, but only from a plan file. The stairs card now has a "Guard and handrail" field: the number of guarded sides (1 or 2) and optionally the handrail height. The result shows under the stair and the rails join the cutting-stock order.
Checked by clicking it through in Chromium on a 9 ft rise (accepted with 2, 36, and 3 refused with a message), plus a source test of the wiring. The layout arithmetic is the engine's existing hand-computed tests; no real built stair was compared, and the code edition is the user's to confirm.