A symbol font's glyphs straddle the cap box by design — the diameter sign's
stroke overhangs it top and bottom — so anchoring a top-aligned line by the
nominal cap height alone hung it above where the drawing puts it, by the size
of the overhang.
Measure how far the first line's glyphs reach above the baseline and anchor by
that when it exceeds the cap. The fold is one-directional, so ordinary letters
(which stop at the cap) keep their exact previous offset.
The test pins the benchmark's own case: without this, the glyph draws from
0.7372 instead of the insertion point — matching the offset measured against
the file's own LINE endpoints for handle 1087.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
