M4: justified Chinese, Japanese and Korean text spreads the room between its characters (#1970)

Cause: justified lines only widened their spaces, so a line of ideographs, written without any,
kept its natural width and its right edge never reached the box's.

Fix: the room on a line (but a paragraph's last) also goes into the gaps next to an ideograph,
kana, Hangul or full-width form wherever a line could break there (`breaks::justify_between`,
beside `break_between`): each is a word of its own, as for line breaking, and no gap opens before a
closing mark or after an opening one. Spaces widen as before; mixed text widens both.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

crates/text/src/breaks.rs

@@ -79,6 +79,15 @@ pub(crate) fn is_space(c: char) -> bool {
     class(c) == Class::Space
 }
 
+/// Whether justified text may widen the gap between `a` and the `b` after it (a space widens on
+/// its own): next to an ideograph, kana, Hangul or full-width form, which are written without
+/// spaces, so each is a word of its own, as for line breaking, wherever a line may break there (no
+/// gap before a closing mark or after an opening one).
+pub(crate) fn justify_between(a: char, b: char) -> bool {
+    let (ca, cb) = (class(a), class(b));
+    (ca == Class::Ideo || cb == Class::Ideo) && ca != Class::Space && break_between(a, b)
+}
+
 /// Whether `c` is in a script written without spaces between words that the line segmenter has
 /// word data for (UAX #14 class SA): Thai, Lao, Burmese (with the Myanmar extensions) and Khmer.
 fn writes_no_spaces(c: char) -> bool {

crates/text/src/layout.rs

@@ -1259,8 +1259,13 @@ pub fn layout(text: &TextData, box_width: Option<f64>, box_height: Option<f64>)
         let hang_r =
             items.get(vis_end.wrapping_sub(1)).filter(|it| hang_end && !rtl_line && vis_end > *s + 1 && closes(it.ch)).map_or(0.0, |it| it.adv);
         let gstart = out.glyphs.len();
-        // Justify: extra space per gap.
-        let gaps = items.get(*s..vis_end).unwrap_or(&[]).iter().filter(|it| it.stretches()).count();
+        // Justify: extra space per gap (a space, or between ideographs, whose text has no spaces).
+        let widens = |k: usize| {
+            items.get(k).is_some_and(|it| {
+                it.stretches() || (k + 1 < vis_end && items.get(k + 1).is_some_and(|next| crate::breaks::justify_between(it.ch, next.ch)))
+            })
+        };
+        let gaps = (*s..vis_end).filter(|k| widens(*k)).count();
         let justify_extra = match (text.align_h, wrap) {
             (TextAlignH::Justified, Some(maxw)) if !para_end && !line_break_after(&items, *e) && gaps > 0 => {
                 ((maxw - line_indent + hang_l + hang_r - width) / gaps as f64).max(0.0)
@@ -1349,13 +1354,14 @@ pub fn layout(text: &TextData, box_width: Option<f64>, box_height: Option<f64>)
         } else {
             (0..line_items.len()).collect()
         };
-        for it in order.iter().filter_map(|k| line_items.get(*k)) {
+        for k in order.iter().copied() {
+            let Some(it) = line_items.get(k) else { continue };
             if is_line_break(it.ch) {
                 continue;
             }
             out.glyphs.extend(glyph_at(&styles, it, pen, baseline));
             pen += it.adv;
-            if it.stretches() {
+            if widens(*s + k) {
                 pen += justify_extra;
             }
         }

crates/text/src/tests.rs

@@ -590,6 +590,51 @@ fn lower_case_writes_final_sigma() {
     assert_eq!(gids(&t).iter().map(|g| g.0).collect::<Vec<_>>(), want.iter().map(|g| g.0).collect::<Vec<_>>(), "split runs");
 }
 
+/// Chinese is written without spaces: justified, the room goes between its characters (each a word
+/// of its own, as for line breaking), so the last one reaches the right edge too, and none opens
+/// where a line couldn't break (before a closing mark, after an opening one). "Justify aligns the
+/// first word in each line of text to the left-most edge, and the last to the right-most edge."
+#[test]
+fn justified_ideographs_spread_the_room_between_characters() {
+    if !have_fonts() {
+        return;
+    }
+    let lay_out = |s: &str, align, w| {
+        let mut t = TextData::new(s);
+        t.style.font_size = 20.0;
+        t.align_h = align;
+        t.auto_resize = figcraft_doc::TextAutoResize::Height;
+        layout(&t, w, None)
+    };
+    // Box width cut inside char `fit`, so the first line is chars 0..fit; how many gaps lie before
+    // each of its chars.
+    for (s, fit, gaps_before, why) in [
+        ("一二三四五六七八九十", 6, [0, 1, 2, 3, 4, 5], "one gap between each pair of ideographs"),
+        ("一二三。四五六七八九", 6, [0, 1, 2, 2, 3, 4], "none before the full stop, which never starts a line"),
+        ("一二三「四五六七八九", 6, [0, 1, 2, 3, 3, 4], "none after the opening bracket, which never ends a line"),
+    ] {
+        let natural = lay_out(s, TextAlignH::Left, None);
+        let (fits, next) = (natural.caret(fit).0, natural.caret(fit + 1).0);
+        assert!(next > fits, "{why}: chars need advances");
+        let w = fits + (next - fits) / 4.0;
+        let left = lay_out(s, TextAlignH::Left, Some(w));
+        let just = lay_out(s, TextAlignH::Justified, Some(w));
+        assert!(just.lines.len() >= 2 && just.lines[0].char_end == fit, "{why}: {:?}", just.lines);
+        let extra = (w - left.lines[0].width) / f64::from(gaps_before[fit - 1]);
+        assert!(extra > 0.0, "{why}");
+        assert_eq!(left.glyphs.len(), just.glyphs.len());
+        for (l, j) in left.glyphs.iter().zip(&just.glyphs).filter(|(g, _)| g.char_end <= fit) {
+            let want = f64::from(gaps_before[l.char_start]) * extra;
+            assert!((j.x - l.x - want).abs() < 1e-6, "{why}: char {} moved {} (want {want})", l.char_start, j.x - l.x);
+        }
+        let last = just.glyphs.iter().rfind(|g| g.char_end <= fit).unwrap();
+        assert!((last.x + last.advance - w).abs() < 1e-6, "{why}: the last char ends at the right edge, not {}", last.x + last.advance);
+        // The last line is left-aligned, as always.
+        let (l2, j2) = (left.glyphs.iter().find(|g| g.char_start == fit).unwrap(), just.glyphs.iter().find(|g| g.char_start == fit).unwrap());
+        assert!((j2.x - l2.x).abs() < 1e-6, "{why}: the last line is not justified");
+    }
+}
+
 /// Thai is written without spaces between words; U+200B ZERO WIDTH SPACE marks where a line may
 /// break. ภาษา|ไทย|เขียน|ติดกัน ("Thai is written joined up") ไม่มี|ช่องว่าง|ระหว่าง|คำ ("with no
 /// spaces between words"), with one real space between the two phrases.

docs/target-app-parity.md

@@ -1,6 +1,6 @@
 # FigCraft parity with Figma
 
-> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-11-01 · **Change:** minor (bulleted lists use the same bullet at every level of indentation, as the help center says, instead of a white bullet and a square at the deeper levels; typing `1)` and a space at the start of a paragraph starts a numbered list, as `1.` does, both being the help center's creation characters; a link on text is underlined by default, as the help center says, and Underline takes the underline off while the link stays; a Dash cap setting (none, round or square) on Dash and Custom strokes, drawn on both ends of every dash; gap 6: widgets draw lines and SVG pictures (plugin API 6); gap 6: a widget opens its plugin's panel (plugin API 5), whose callbacks redraw it; the browser build uses the fonts installed on the computer once asked, each read when text uses it (#1051); plugin widgets have hover styles: a layer's `hover` fill, stroke, opacity or text colour shows while the pointer is over it (gap 6); Thai, Lao, Khmer and Burmese lines break between words (#1219); MCP and control calls name their document (#998); shadows of images with transparent pixels follow their alpha (#1289); Arabic draft catalog; truncated text fills its last line before the ellipsis and keeps truncating when resized; auto-height text with max lines (#1375, #1376, #1377), numbers unchanged; plugin widgets take text input and a property menu (plugin API 4); boards: templates and tables; boards: a shared timer and voting sessions; boards: the dot grid, connector ends dragged to re-attach, curved connectors; `.sketch` import, best effort: import/export breadth 86% → 87%, file formats 60% → 61%, headline numbers unchanged; Canvas & navigation's remaining work no longer lists outline mode's Include hidden layers and Include object bounds; boards: area 22 (weight 0, outside the weighted sum); CJK line breaking: JIS X 4051's line-start and line-end sets completed with the halfwidth small kana, the halfwidth and spacing (semi-)voiced sound marks, iteration marks 〱–〵 and the halfwidth parentheses; Turkish reviewed, Czech and Indonesian drafts, the Japanese draft completed; reviewed Russian catalog and integer plurals; vector edit mode regions: hover hatch, selection and drag; plugin log byte/count limits (#191); core editor leftovers: component playground, auto gap handles, variables inside styles, inner shadows and background blur on groups, command-made text readable on dark pages, a one-step frame/group convert, delays on mouse triggers and manual overlay offsets, wrapped-line alignment; starter templates, a Templates tab and Getting started tips on the home screen: essentials ~57% → ~59%; everyday editing partials: number fields, outline options, Hide when publishing, cursors, panel widths, dark pages, numbers unchanged but menu breadth 211/211; text box sizes measured against documents re-saved by other software: whole-pixel line heights, advances on a 1024-per-em grid, letter spacing between glyphs only, numbers unchanged; .fig export checked by opening written files in other software, numbers unchanged; a public figcraft-server: open hosting, owner tokens, per-address limits, idle expiry, moderation, install.sh; experimental .fig export; keyboard shortcut parity suite and bindings; Simplified Chinese draft catalog; Latin American Spanish overlay; prototyping tail: gamepad triggers, widgets in prototypes, mode lookups; plugin directory on figcraft-server; Japanese and Korean draft catalogs and CJK UI fonts; plugin widgets and the plugin panel tail; French, German and Brazilian Portuguese draft catalogs; cursor chat and spotlight in live sessions; layers and assets panels behaviour suite and fixes; vector multi-edit and edit tail; dev resources links; extended collections tail; branch version history and finer list merges; headline percentages recomputed from the area table: feature breadth ~84%, core ~94%, mainstream ~50%; text lists, hanging punctuation and decoration styles; comments and version history behaviour suite and fixes; canvas navigation, guides and grids behaviour suite and fixes; export and inspect behaviour suite and fixes; .fig import: editable vector networks and more layer kinds; shapes and vector behaviour suite and fixes; paint and effects behaviour suite and fixes; frames, groups, sections and masks behaviour suite and fixes; styles and variables behaviour suite and fixes; prototyping behaviour suite and fixes; components behaviour suite and fixes; embedded image colour profiles; layers panel keyboard: F2 rename, Shift+F10 context menu, keyboard box selection, 10k-layer QA; per-side stroke weight variables; text behaviour suite: CJK line breaking, metrics, vertical trim; selection and transform behaviour suite and fixes; `.fig` import, best effort; auto layout behaviour suite and fixes; Display P3: gamut warning and soft-proof (true P3 blocked upstream); several windows; localization layer with a draft Spanish catalog; hostingLine truncated
+> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-11-04 · **Change:** patch (justified Chinese, Japanese and Korean text, written without spaces, spreads each line's room between its characters so its right edge aligns (#1970); bulleted lists use the same bullet at every level of indentation, as the help center says, instead of a white bullet and a square at the deeper levels; typing `1)` and a space at the start of a paragraph starts a numbered list, as `1.` does, both being the help center's creation characters; a link on text is underlined by default, as the help center says, and Underline takes the underline off while the link stays; a Dash cap setting (none, round or square) on Dash and Custom strokes, drawn on both ends of every dash; gap 6: widgets draw lines and SVG pictures (plugin API 6); gap 6: a widget opens its plugin's panel (plugin API 5), whose callbacks redraw it; the browser build uses the fonts installed on the computer once asked, each read when text uses it (#1051); plugin widgets have hover styles: a layer's `hover` fill, stroke, opacity or text colour shows while the pointer is over it (gap 6); Thai, Lao, Khmer and Burmese lines break between words (#1219); MCP and control calls name their document (#998); shadows of images with transparent pixels follow their alpha (#1289); Arabic draft catalog; truncated text fills its last line before the ellipsis and keeps truncating when resized; auto-height text with max lines (#1375, #1376, #1377), numbers unchanged; plugin widgets take text input and a property menu (plugin API 4); boards: templates and tables; boards: a shared timer and voting sessions; boards: the dot grid, connector ends dragged to re-attach, curved connectors; `.sketch` import, best effort: import/export breadth 86% → 87%, file formats 60% → 61%, headline numbers unchanged; Canvas & navigation's remaining work no longer lists outline mode's Include hidden layers and Include object bounds; boards: area 22 (weight 0, outside the weighted sum); CJK line breaking: JIS X 4051's line-start and line-end sets completed with the halfwidth small kana, the halfwidth and spacing (semi-)voiced sound marks, iteration marks 〱–〵 and the halfwidth parentheses; Turkish reviewed, Czech and Indonesian drafts, the Japanese draft completed; reviewed Russian catalog and integer plurals; vector edit mode regions: hover hatch, selection and drag; plugin log byte/count limits (#191); core editor leftovers: component playground, auto gap handles, variables inside styles, inner shadows and background blur on groups, command-made text readable on dark pages, a one-step frame/group convert, delays on mouse triggers and manual overlay offsets, wrapped-line alignment; starter templates, a Templates tab and Getting started tips on the home screen: essentials ~57% → ~59%; everyday editing partials: number fields, outline options, Hide when publishing, cursors, panel widths, dark pages, numbers unchanged but menu breadth 211/211; text box sizes measured against documents re-saved by other software: whole-pixel line heights, advances on a 1024-per-em grid, letter spacing between glyphs only, numbers unchanged; .fig export checked by opening written files in other software, numbers unchanged; a public figcraft-server: open hosting, owner tokens, per-address limits, idle expiry, moderation, install.sh; experimental .fig export; keyboard shortcut parity suite and bindings; Simplified Chinese draft catalog; Latin American Spanish overlay; prototyping tail: gamepad triggers, widgets in prototypes, mode lookups; plugin directory on figcraft-server; Japanese and Korean draft catalogs and CJK UI fonts; plugin widgets and the plugin panel tail; French, German and Brazilian Portuguese draft catalogs; cursor chat and spotlight in live sessions; layers and assets panels behaviour suite and fixes; vector multi-edit and edit tail; dev resources links; extended collections tail; branch version history and finer list merges; headline percentages recomputed from the area table: feature breadth ~84%, core ~94%, mainstream ~50%; text lists, hanging punctuation and decoration styles; comments and version history behaviour suite and fixes; canvas navigation, guides and grids behaviour suite and fixes; export and inspect behaviour suite and fixes; .fig import: editable vector networks and more layer kinds; shapes and vector behaviour suite and fixes; paint and effects behaviour suite and fixes; frames, groups, sections and masks behaviour suite and fixes; styles and variables behaviour suite and fixes; prototyping behaviour suite and fixes; components behaviour suite and fixes; embedded image colour profiles; layers panel keyboard: F2 rename, Shift+F10 context menu, keyboard box selection, 10k-layer QA; per-side stroke weight variables; text behaviour suite: CJK line breaking, metrics, vertical trim; selection and transform behaviour suite and fixes; `.fig` import, best effort; auto layout behaviour suite anLine truncated
 
 The authoritative assessment of how close FigCraft is to Figma Design. [`ROADMAP.md`](../ROADMAP.md)
 summarizes it; [`gaps.md`](gaps.md) is the ranked work list; the measured menu checklist is
@@ -297,7 +297,7 @@ Hours in this narrative are the builders' estimates; the tables above supersede
    break inside Latin words, kinsoku to JIS X 4051 for closing and opening punctuation, small kana
    (halfwidth too), the prolonged sound mark, the iteration marks, the (semi-)voiced sound marks
    and the halfwidth parentheses); Thai, Lao, Khmer and Burmese lines break between words (ICU4X's word
-   dictionaries, its LSTM models in the browser), never after a leading vowel or before a mark; a style's metrics from its own font, not a fallback; a letter and
+   dictionaries, its LSTM models in the browser), never after a leading vowel or before a mark; justified text widens each line's spaces but the last line's, and in Chinese, Japanese and Korean text, which has none, the gaps between its characters wherever a line could break (#1970); a style's metrics from its own font, not a fallback; a letter and
    its combining marks (Vietnamese typed decomposed, say) from one font that has them all; carets, Delete and
    Backspace by grapheme cluster; double-click and word moves by script run; IME composition with
    CJK; vertical trim (cap height to baseline). The tail suite (`crates/text/src/tail_tests.rs`,
@@ -648,6 +648,7 @@ Carried over from the ROADMAP's "Shipped so far" (2026-10-10). The test count th
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-11-04 | patch | M4, #1970: justified Chinese, Japanese and Korean text, written without spaces between words, aligns its right edge: the room on each line but a paragraph's last goes between its characters, each a word of its own as for line breaking ("Justify aligns the first word in each line of text to the left-most edge, and the last to the right-most edge"), wherever a line could break there, so none opens before a full stop or closing bracket, nor after an opening one. Latin text widens its spaces as before; mixed text widens both. `figcraft_text::breaks::justify_between`, beside `break_between`, says where. Evidence: `tests::justified_ideographs_spread_the_room_between_characters` (fails on main). |
 | 2026-11-01 | patch | M4: bulleted lists draw the same bullet at every level of indentation ("Figma bullets will keep the same styling at all levels of indentation", Create bulleted and numbered lists); the deeper levels drew a white bullet and a small square, pinned as silent before. Numbered levels (1., a., i.) are unchanged. Found by a documentation audit of the text rules. Test: `tail_tests::list_numbering_by_level` (the bullets row). Numbers unchanged |
 | 2026-11-01 | patch | M4: typing `1)` followed by a space at the start of a plain paragraph starts a numbered list, as `1.` already did ("Enter one of the creation characters below followed by a Space: 1. 1)", Create bulleted and numbered lists). Found by a documentation audit of the text rules. Test: `text_tail_tests::typing_a_creation_character_and_a_space_starts_a_list`. Numbers unchanged |
 | 2026-11-01 | patch | M4: a link made with `text.link` (Cmd/Ctrl+K, Shift+Cmd/Ctrl+U) underlines the linked text unless it has a decoration of its own ("Links are styled with an underline by default. Use the keyboard shortcut to remove the underline", Add links to text); Underline (Cmd/Ctrl+U) takes the underline off and the link stays. Found by a documentation audit of the text rules. Test: `text_behaviour_tests::a_link_is_underlined_by_default_and_underline_takes_it_off`. Numbers unchanged |