lexmount · ldm0 · Sep 7, 2026 · Sep 7, 2026
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/moli-core/tests/fixtures/runtime/chrome_fontfaceset_events_subset.html b/moli-core/tests/fixtures/runtime/chrome_fontfaceset_events_subset.html
@@ -2,6 +2,9 @@
 <html>
   <body data-order="" data-count="" data-ready-status="">
     <script>
+  // Real project-generated font: moli-layout/tests/fixtures/moli-ahem.woff2.
+  const FONT_FIXTURE_SOURCE = "url(data:font/woff2;base64,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)";
+      document.fonts.add(new FontFace('FixtureFace', FONT_FIXTURE_SOURCE));
       const body = document.body;
       const events = [];
 
@@ -10,7 +13,7 @@
       document.fonts.onloadingerror = (event) => events.push(event.type);
 
       document.fonts
-        .load('10px sans-serif')
+        .load('10px FixtureFace')
         .then(() => document.fonts.ready)
         .then(() => {
           body.setAttribute('data-order', events.join(','));

diff --git a/moli-core/tests/fixtures/runtime/document_fonts_events.html b/moli-core/tests/fixtures/runtime/document_fonts_events.html
@@ -2,6 +2,9 @@
 <html>
   <body data-loading-a="" data-loading-b="" data-loadingdone="">
     <script>
+  // Real project-generated font: moli-layout/tests/fixtures/moli-ahem.woff2.
+  const FONT_FIXTURE_SOURCE = "url(data:font/woff2;base64,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)";
+      document.fonts.add(new FontFace('Roboto', FONT_FIXTURE_SOURCE));
       let loadingA = 0;
       let loadingB = 0;
       let loadingDone = 0;
@@ -22,11 +25,11 @@
       document.fonts.addEventListener('loading', onLoadingB);
       document.fonts.addEventListener('loadingdone', onLoadingDone);
       document.fonts.removeEventListener('loading', onLoadingA);
-      document.fonts.load('italic bold 16px Roboto');
-
-      document.body.setAttribute('data-loading-a', String(loadingA));
-      document.body.setAttribute('data-loading-b', String(loadingB));
-      document.body.setAttribute('data-loadingdone', String(loadingDone));
+      document.fonts.load('italic bold 16px Roboto').then(() => document.fonts.ready).then(() => {
+        document.body.setAttribute('data-loading-a', String(loadingA));
+        document.body.setAttribute('data-loading-b', String(loadingB));
+        document.body.setAttribute('data-loadingdone', String(loadingDone));
+      });
     </script>
   </body>
 </html>
diff --git a/moli-core/tests/fixtures/runtime/local_event_target_callback_exception.html b/moli-core/tests/fixtures/runtime/local_event_target_callback_exception.html
@@ -12,6 +12,9 @@
   data-simple-error=""
 >
 <script>
+  // Real project-generated font: moli-layout/tests/fixtures/moli-ahem.woff2.
+  const FONT_FIXTURE_SOURCE = "url(data:font/woff2;base64,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)";
+  document.fonts.add(new FontFace('Roboto', FONT_FIXTURE_SOURCE));
   const body = document.body;
 
   const fontOrder = [];

diff --git a/moli-core/tests/fixtures/runtime/servo_fontfaceset_load_ready.html b/moli-core/tests/fixtures/runtime/servo_fontfaceset_load_ready.html
@@ -9,6 +9,9 @@
     data-css-wide-keyword-prefixed=""
   >
     <script>
+  // Real project-generated font: moli-layout/tests/fixtures/moli-ahem.woff2.
+  const FONT_FIXTURE_SOURCE = "url(data:font/woff2;base64,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)";
+      document.fonts.add(new FontFace('FixtureFace', FONT_FIXTURE_SOURCE));
       (async () => {
         const body = document.body;
         const ready1 = document.fonts.ready;

diff --git a/moli-css-parse/src/font_face.rs b/moli-css-parse/src/font_face.rs
@@ -4,6 +4,121 @@ use crate::unquote_css_string;
 
 pub use style::moli_font_face::{CssFontFace, normalize_font_face_src, parse_font_faces};
 
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum CssFontSource {
+    Local(String),
+    Url(String),
+}
+
+/// Parse through Stylo first; the token walk only extracts validated sources.
+pub fn parse_font_face_sources(source: &str) -> Option<Vec<CssFontSource>> {
+    let normalized = normalize_font_face_src(source)?;
+    let mut input = ParserInput::new(&normalized);
+    let mut parser = Parser::new(&mut input);
+    parser
+        .parse_comma_separated(|parser| {
+            let name = parser.expect_function()?.clone();
+            let source = parser.parse_nested_block(|nested| {
+                if name.eq_ignore_ascii_case("local") {
+                    let mut parts = Vec::new();
+                    while !nested.is_exhausted() {
+                        parts.push(nested.expect_ident_or_string()?.to_string());
+                    }
+                    Ok(CssFontSource::Local(parts.join(" ")))
+                } else if name.eq_ignore_ascii_case("url") {
+                    Ok(CssFontSource::Url(nested.expect_string()?.to_string()))
+                } else {
+                    Err(nested.new_custom_error(()))
+                }
+            })?;
+            let mut supported = true;
+            while !parser.is_exhausted() {
+                let kind = parser.expect_function()?.clone();
+                parser.parse_nested_block(|nested| {
+                    let mut values = Vec::new();
+                    while !nested.is_exhausted() {
+                        if nested.try_parse(|p| p.expect_comma()).is_ok() {
+                            continue;
+                        }
+                        values.push(nested.expect_ident_or_string()?.to_ascii_lowercase());
+                    }
+                    supported &= kind.eq_ignore_ascii_case("format")
+                        && values.iter().all(|v| {
+                            matches!(
+                                v.as_str(),
+                                "woff" | "woff2" | "truetype" | "opentype" | "collection"
+                            )
+                        });
+                    Ok::<_, cssparser::ParseError<'_, ()>>(())
+                })?;
+            }
+            Ok(supported.then_some(source))
+        })
+        .ok()
+        .map(|sources| sources.into_iter().flatten().collect())
+}
+
+#[derive(Clone, Debug)]
+pub struct CssFontShorthand {
+    pub family_css: String,
+    pub families: Vec<String>,
+    pub size: String,
+    pub style: String,
+    pub weight: String,
+    pub stretch: String,
+}
+
+/// Shares the CSS font grammar with style declarations, including quoted
+/// multi-word families and fallback lists. No guessed last-whitespace token.
+pub fn parse_font_shorthand(value: &str) -> Option<CssFontShorthand> {
+    use style::{
+        properties::{PropertyId, parse_property_declaration_list},
+        stylesheets::CssRuleType,
+    };
+    use style_traits::CssStringWriter;
+    if crate::escape_top_level_semicolons(value) != value
+        || crate::split_important_priority(value).1
+    {
+        return None;
+    }
+    crate::stylo_stylesheet::with_descriptor_declaration_context(CssRuleType::Style, |context| {
+        let text = format!("font: {value}");
+        let mut input = ParserInput::new(&text);
+        let block = parse_property_declaration_list(context, &mut Parser::new(&mut input), &[]);
+        let property = |name: &str| -> Option<String> {
+            let mut out = CssStringWriter::new();
+            block
+                .property_value_to_css(&PropertyId::parse(name, context).ok()?, &mut out)
+                .ok()?;
+            (!out.is_empty()).then(|| out.to_string())
+        };
+        let family_css = property("font-family")?;
+        let size = property("font-size")?;
+        if is_css_wide_keyword(&size) || size.contains("var(") {
+            return None;
+        }
+        let mut input = ParserInput::new(&family_css);
+        let families = Parser::new(&mut input)
+            .parse_comma_separated(|p| {
+                let mut parts = Vec::new();
+                while !p.is_exhausted() {
+                    parts.push(p.expect_ident_or_string()?.to_string());
+                }
+                Ok::<_, cssparser::ParseError<'_, ()>>(parts.join(" "))
+            })
+            .ok()?;
+        drop(input);
+        Some(CssFontShorthand {
+            family_css,
+            families,
+            size,
+            style: property("font-style")?,
+            weight: property("font-weight")?,
+            stretch: property("font-stretch")?,
+        })
+    })
+}
+
 pub fn font_load_query_contains_css_wide_keyword(query: &str) -> bool {
     let mut input = ParserInput::new(query);
     let mut input = Parser::new(&mut input);
@@ -50,6 +165,40 @@ fn is_css_wide_keyword(value: &str) -> bool {
 
 #[cfg(test)]
 mod tests {
+    #[test]
+    fn font_sources_preserve_local_names_and_supported_url_fallback_order() {
+        use super::*;
+        assert_eq!(
+            parse_font_face_sources(
+                "local(Missing Font), url(bad) format('unsupported'), url(good.woff2) format('woff2')"
+            ),
+            Some(vec![
+                CssFontSource::Local("Missing Font".into()),
+                CssFontSource::Url("good.woff2".into())
+            ])
+        );
+        assert!(parse_font_face_sources("not a source").is_none());
+    }
+
+    #[test]
+    fn font_shorthand_uses_stylo_validation_and_keeps_all_families() {
+        let font =
+            super::parse_font_shorthand("italic bold 10.5px/1.2 \"A B\", Another Face, serif")
+                .unwrap();
+        assert_eq!(font.families, ["A B", "Another Face", "serif"]);
+        assert_eq!(font.size, "10.5px");
+        assert_eq!(font.style, "italic");
+        for invalid in [
+            "",
+            "12px",
+            "not a font",
+            "inherit",
+            "12px serif; color:red",
+            "12px serif !important",
+        ] {
+            assert!(super::parse_font_shorthand(invalid).is_none(), "{invalid}");
+        }
+    }
     use super::{
         font_load_query_contains_css_wide_keyword, font_load_query_family, normalize_font_face_src,
         parse_font_faces,

diff --git a/moli-css-parse/src/lib.rs b/moli-css-parse/src/lib.rs
@@ -19,8 +19,9 @@ pub use color::{
 };
 pub use declaration::{CssDeclaration, DeclarationParseOptions, parse_declaration_list};
 pub use font_face::{
-    CssFontFace, font_load_query_contains_css_wide_keyword, font_load_query_family,
-    normalize_font_face_src, parse_font_faces,
+    CssFontFace, CssFontShorthand, CssFontSource, font_load_query_contains_css_wide_keyword,
+    font_load_query_family, normalize_font_face_src, parse_font_face_sources, parse_font_faces,
+    parse_font_shorthand,
 };
 pub use math::{
     ContainerQueryLengthContext, CssNumericContext, CssNumericKind, CssNumericValue, UnitlessAngle,

diff --git a/moli-css-parse/src/stylo_stylesheet.rs b/moli-css-parse/src/stylo_stylesheet.rs
@@ -234,7 +234,7 @@ fn declaration_block_css_text(block: &PropertyDeclarationBlock) -> String {
     css_text.trim_end().to_owned()
 }
 
-fn with_descriptor_declaration_context<R>(
+pub(crate) fn with_descriptor_declaration_context<R>(
     rule_type: CssRuleType,
     f: impl FnOnce(&ParserContext) -> Option<R>,
 ) -> Option<R> {

diff --git a/moli-layout/Cargo.toml b/moli-layout/Cargo.toml
@@ -9,6 +9,7 @@ euclid = "=0.22.14"
 kurbo = "=0.13.1"
 moli-image = { path = "../moli-image" }
 parley = "=0.11.1"
+read-fonts = "=0.41.0"
 parking_lot = "0.12"
 stylo = "0.20"
 stylo_taffy = { git = "https://github.com/DioxusLabs/blitz", rev = "5081c65811a4396f5a99b2e0aca542a4a4a6606f", default-features = false, features = ["std", "block", "flexbox", "grid", "floats"] }

diff --git a/moli-layout/src/lib.rs b/moli-layout/src/lib.rs
@@ -98,7 +98,7 @@ pub use style::{
     LayoutPosition, ResolvedLayoutStyle,
 };
 pub use text::{
-    DocumentLayoutServices, SystemFontPolicy, WebFontFace, WebFontRegistration,
+    DocumentLayoutServices, FontFaceData, SystemFontPolicy, WebFontFace, WebFontRegistration,
     WebFontRegistrationError, WebFontRegistrationOutcome, WebFontStyle, WebFontUnicodeRange,
 };
 pub use world::{

diff --git a/moli-layout/src/text.rs b/moli-layout/src/text.rs
@@ -23,6 +23,9 @@ use thiserror::Error;
 use crate::stylo_to_parley::TextBrush;
 use crate::system_fonts::SystemFontFamilyResolver;
 
+mod font_source;
+pub use font_source::FontFaceData;
+
 pub(crate) struct ParleyDocumentServices {
     pub(crate) font_context: FontContext,
     pub(crate) layout_context: LayoutContext<TextBrush>,
@@ -674,6 +677,7 @@ pub struct DocumentLayoutServices {
     // FontContext and LayoutContext are both large. Keep them off the stack so
     // embedding this sidecar in ScriptVm does not inflate every VM frame.
     parley: Option<Box<ParleyDocumentServices>>,
+    local_font_sources: Option<Box<font_source::LocalFontSources>>,
     system_font_policy: SystemFontPolicy,
     web_fonts: BTreeMap<String, RegisteredWebFont>,
     pub(crate) text_layout_passes: u64,
@@ -690,6 +694,7 @@ impl DocumentLayoutServices {
     pub const fn new() -> Self {
         Self {
             parley: None,
+            local_font_sources: None,
             system_font_policy: SystemFontPolicy::Enabled,
             web_fonts: BTreeMap::new(),
             text_layout_passes: 0,
@@ -700,6 +705,7 @@ impl DocumentLayoutServices {
     pub const fn with_system_font_policy(system_font_policy: SystemFontPolicy) -> Self {
         Self {
             parley: None,
+            local_font_sources: None,
             system_font_policy,
             web_fonts: BTreeMap::new(),
             text_layout_passes: 0,
@@ -775,6 +781,18 @@ impl DocumentLayoutServices {
         true
     }
 
+    /// Resolves a CSS local() source by its actual full or PostScript name.
+    /// This never substitutes a generic font or a document web-font alias.
+    pub fn local_font_source(&mut self, name: &str) -> Option<FontFaceData> {
+        self.local_font_sources
+            .get_or_insert_with(|| {
+                Box::new(font_source::LocalFontSources::new(
+                    self.system_font_policy.is_enabled(),
+                ))
+            })
+            .find(name)
+    }
+
     pub(crate) fn parley_mut(&mut self) -> &mut ParleyDocumentServices {
         if self.parley.is_none() {
             self.parley = Some(Box::new(build_parley_services(