Variable: WIDTH_SAFETY_FACTOR

const WIDTH_SAFETY_FACTOR: 1.03 = 1.03

Conservative safety factors applied by the shrink solver (not by the pure measureHeightPt). Raw hmtx advances summed without shaping still pack a line a little tighter than PowerPoint, which lays text out at a device DPI and rounds each glyph advance up — so PowerPoint wraps marginally earlier and its fitted box is marginally taller. Inflating measured width and height by these factors makes the computed fontScale ≤ PowerPoint's across the calibration oracle (test/read/autofit-calibration-oracle.test.js: 0 violations over the Aptos cases). They err on the side of shrinking slightly too much, never overflowing.