Docs: with glyph bounds, the font size follows the vertical scale

docs/mcp.md and docs/target-app-parity.md said that a width or height
typed with Measure Type by Glyph Bounds on changes the font size by the
scale. The font size follows the vertical scale only: a width typed
alone, out of proportion, changes the horizontal scale and keeps the
font size, and a height typed alone changes the horizontal scale the
other way. A new test checks both.

crates/engine/src/tests/typeglyphbounds.rs

@@ -127,6 +127,30 @@ fn set_bounds_moves_and_sizes_the_ink_box() {
     assert!((ink(&s, t).height() - before.height()).abs() < 1e-6, "{:?}", ink(&s, t));
 }
 
+/// The font size the panels show follows the vertical scale: a typed width alone changes the
+/// horizontal scale and keeps the font size, and a typed height alone changes the font size and
+/// keeps the width, so the horizontal scale changes the other way.
+#[test]
+fn a_typed_width_changes_the_horizontal_scale_and_a_typed_height_the_font_size() {
+    let shown = |s: &Session, t: NodeId| {
+        let o = text(s, t);
+        let st = o.effective_char_style(&o.runs[0].style).unwrap();
+        (st.size, st.h_scale)
+    };
+    let (mut s, t) = with_type(json!({"x": 100, "y": 300, "size": 100, "text": "Hg"}));
+    glyphs(&mut s, true);
+    let before = ink(&s, t);
+    run(&mut s, "object.setBounds", json!({"width": before.width() * 2.0}));
+    let (size, h_scale) = shown(&s, t);
+    assert!((size - 100.0).abs() < 1e-6 && (h_scale - 200.0).abs() < 1e-6, "{size} pt at {h_scale}%");
+    let (mut s, t) = with_type(json!({"x": 100, "y": 300, "size": 100, "text": "Hg"}));
+    glyphs(&mut s, true);
+    run(&mut s, "object.setBounds", json!({"height": before.height() * 2.0}));
+    let (size, h_scale) = shown(&s, t);
+    assert!((size - 200.0).abs() < 1e-6 && (h_scale - 50.0).abs() < 1e-6, "{size} pt at {h_scale}%");
+    assert!((ink(&s, t).width() - before.width()).abs() < 1e-6, "{:?}", ink(&s, t));
+}
+
 #[test]
 fn set_bounds_with_the_current_values_records_no_undo_step() {
     let (mut s, t) = with_type(json!({"x": 100, "y": 300, "size": 100, "text": "Hg"}));

docs/mcp.md

@@ -4083,8 +4083,9 @@ outlines and its underline and strikethrough bars. This applies to each point ty
 default.
 
 A width or height typed with the option on scales the type until its ink has that size. The type stays live type: its
-font size changes by the scale, so `object.setBounds {height: 72}` on "H" gives the cap height 72 pt, not a 72 pt
-font. With Use Preview Bounds on, the ink takes in the characters' strokes, and type with geometry effects is
+font size changes by the vertical scale, so `object.setBounds {height: 72}` on "H" gives the cap height 72 pt, not a
+72 pt font. A width typed alone, out of proportion, changes the horizontal scale and keeps the font size, and a height
+typed alone keeps the width, so the horizontal scale changes the other way. With Use Preview Bounds on, the ink takes in the characters' strokes, and type with geometry effects is
 measured as drawn. Rotated type keeps its own angle, and skewed type is measured by its glyph outlines. Type that
 draws nothing (no text, or only spaces without underline or strikethrough), area type, type on a path and type inside
 a selected group are measured as before. Arrange in Grid and Group Overlapping Objects measure visual bounds as

docs/target-app-parity.md

@@ -1070,7 +1070,7 @@ Moved from the ROADMAP's "Shipped so far" on 2026-10-10. Update it when a featur
   - A butt cap ends a stroke square at the end of an open path, and a projecting cap extends half the weight past it. VectorCraft's visual box of a butt-capped stroke on an open path does not grow past the path's ends: a straight segment's box comes from the corners of its stroked rectangle, and a curve's box comes from the stroke at its ends and where its tangent is square to an axis. Round and projecting caps and arrowheads still reach past an end. A curve that bends more tightly than half the weight can measure a little larger than it paints, and a butt-dashed path whose first or last dash is a gap is measured to the path's ends. Public reference: [Apply stroke on an object](https://helpx.adobe.com/illustrator/using/stroke-object.html).
   - A butt-capped curve whose first or last handle sits on its end point also stops at that end: a straight 50 pt curve with a 2 pt stroke and its first handle on its start point measures 50 pt tall, not 51 pt (doc `reach::tests::a_butt_curve_with_a_handle_on_its_end_point_stops_near_that_end`).
   - With Use Preview Bounds on, the bounding box, the Transform panel, Align, Distribute, Distribute Spacing and `object.setBounds` measure each object after its geometry effects. A path is measured by its effected shape, and a fill or stroke with geometry effects of its own is measured by the shape it paints. Type, images, live objects and symbol instances are measured by their reshaped art, and a symbol instance is also measured by its reshaped art when its symbol's art has geometry effects. A group or layer with geometry or Pathfinder effects, or with a fill or stroke of its own that has geometry effects or paints members with geometry effects, is measured by its evaluated art. A blend, envelope or repeat whose objects have geometry effects is measured by its evaluated art, with those objects measured after their effects. A 100 pt square without a stroke, with Offset Path 10, measures 120 pt, and type with Outline Object aligns and sizes by its glyphs. Raster effects are not measured. Public reference: [Create text](https://web.archive.org/web/20220127090642/https://helpx.adobe.com/illustrator/using/creating-text.html) (archived copy).
-  - VectorCraft's own Measure Type by Glyph Bounds (`typeGlyphBounds`, off by default; Preferences › Type and the Transform panel menu): the bounding box, the Transform panel's, Control bar's and Properties panel's X, Y, W and H, `object.setBounds`, Swap Objects, Replace with Top Object, Set Size of Each and Sort Objects measure each point type object selected as an object by the ink of its glyphs, underline and strikethrough included, instead of its em box. A typed W or H scales the live type until its ink has that size, and the font size changes by the scale. Moved type snaps by its ink box. Type that draws nothing, area type, type on a path and type in a selected group are measured as before, and Align and Distribute follow Align to Glyph Bounds (`tests::typeglyphbounds`, `panels::transform::tests::measure_type_by_glyph_bounds_is_checked_and_resizes_the_box`).
+  - VectorCraft's own Measure Type by Glyph Bounds (`typeGlyphBounds`, off by default; Preferences › Type and the Transform panel menu): the bounding box, the Transform panel's, Control bar's and Properties panel's X, Y, W and H, `object.setBounds`, Swap Objects, Replace with Top Object, Set Size of Each and Sort Objects measure each point type object selected as an object by the ink of its glyphs, underline and strikethrough included, instead of its em box. A typed W or H scales the live type until its ink has that size; the font size follows the vertical scale, so a W typed alone, out of proportion, changes the horizontal scale instead. Moved type snaps by its ink box. Type that draws nothing, area type, type on a path and type in a selected group are measured as before, and Align and Distribute follow Align to Glyph Bounds (`tests::typeglyphbounds`, `panels::transform::tests::measure_type_by_glyph_bounds_is_checked_and_resizes_the_box`).
   - Initial live Revolve (#605, #846): a portable geometry and shading crate (`three-d`), editable path and compound profiles, compact options with artboard rotation and light gizmos, SVG/PDF vector output and Expand Appearance that can trim covered faces. Cap is on by default with continuous curved vector rims; shading uses vector gradients automatically, with sharp profile corners, uniform caps and round seam joins. One light and approximate visibility remain ([revolve.md](revolve.md)).
   - Effect › Path › Outline Object has no options. Type that carries it is drawn, exported (PDF and SVG as paths, with no font) and expanded as its glyph outlines while it stays editable, and the effects after it reshape those outlines. Paths and images draw as before. With Use Preview Bounds on, type is still measured by its layout box. Public reference: [Summary of effects](https://web.archive.org/web/20210901011839/https://helpx.adobe.com/illustrator/using/summary-effects.html) (archived copy).
   - Initial live Revolve (#605, #846): a portable geometry and shading crate (`three-d`), editable path and compound profiles, compact options with artboard rotation and light gizmos, SVG/PDF vector output and Expand Appearance that can trim covered faces. Cap is on by default with continuous curved vector rims; shading uses vector gradients automatically, with sharp profile corners, uniform caps and round seam joins. The Lights list, Add Light and Delete Light manage one to ten independent colored lights; ambient is shared and visibility remains approximate ([revolve.md](revolve.md)).