feat: [WIP] allow specifying alt text for links

skip-checks:true

# Please enter the commit message for your changes. Lines starting
# with '#' will be kept; you may remove them yourself if you want to.
# An empty message aborts the commit.
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# Date:      Wed May 28 17:47:35 2025 +0200
#
# On branch pdf-accessibility
# Your branch and 'origin/pdf-accessibility' have diverged,
# and have 11 and 5 different commits each, respectively.
#
# Changes to be committed:
#	modified:   crates/typst-ide/src/jump.rs
#	modified:   crates/typst-layout/src/flow/distribute.rs
#	modified:   crates/typst-layout/src/modifiers.rs
#	modified:   crates/typst-library/src/foundations/content.rs
#	modified:   crates/typst-library/src/layout/frame.rs
#	modified:   crates/typst-library/src/model/bibliography.rs
#	modified:   crates/typst-library/src/model/footnote.rs
#	modified:   crates/typst-library/src/model/link.rs
#	modified:   crates/typst-library/src/model/outline.rs
#	modified:   crates/typst-library/src/model/reference.rs
#	modified:   crates/typst-pdf/src/convert.rs
#	modified:   crates/typst-pdf/src/link.rs
#	modified:   crates/typst-render/src/lib.rs
#	modified:   crates/typst-svg/src/lib.rs
#	modified:   tests/src/run.rs
#

crates/typst-eval/src/call.rs

@@ -37,7 +37,12 @@ impl Eval for ast::FuncCall<'_> {
             let target = access.target();
             let field = access.field();
             match eval_field_call(target, field, args, span, vm)? {
-                FieldCall::Normal(callee, args) => (callee, args),
+                FieldCall::Normal(callee, args) => {
+                    if vm.inspected == Some(callee_span) {
+                        vm.trace(callee.clone());
+                    }
+                    (callee, args)
+                }
                 FieldCall::Resolved(value) => return Ok(value),
             }
         } else {

crates/typst-ide/src/complete.rs

@@ -15,7 +15,7 @@ use typst::syntax::{
     ast, is_id_continue, is_id_start, is_ident, FileId, LinkedNode, Side, Source,
     SyntaxKind,
 };
-use typst::text::RawElem;
+use typst::text::{FontFlags, RawElem};
 use typst::visualize::Color;
 use unscanny::Scanner;
 
@@ -1081,6 +1081,24 @@ fn code_completions(ctx: &mut CompletionContext, hash: bool) {
     }
 }
 
+/// See if the AST node is somewhere within a show rule applying to equations
+fn is_in_equation_show_rule(leaf: &LinkedNode<'_>) -> bool {
+    let mut node = leaf;
+    while let Some(parent) = node.parent() {
+        if_chain! {
+            if let Some(expr) = parent.get().cast::<ast::Expr>();
+            if let ast::Expr::ShowRule(show) = expr;
+            if let Some(ast::Expr::FieldAccess(field)) = show.selector();
+            if field.field().as_str() == "equation";
+            then {
+                return true;
+            }
+        }
+        node = parent;
+    }
+    false
+}
+
 /// Context for autocompletion.
 struct CompletionContext<'a> {
     world: &'a (dyn IdeWorld + 'a),
@@ -1152,10 +1170,12 @@ impl<'a> CompletionContext<'a> {
 
     /// Add completions for all font families.
     fn font_completions(&mut self) {
-        let equation = self.before_window(25).contains("equation");
+        let equation = is_in_equation_show_rule(self.leaf);
         for (family, iter) in self.world.book().families() {
-            let detail = summarize_font_family(iter);
-            if !equation || family.contains("Math") {
+            let variants: Vec<_> = iter.collect();
+            let is_math = variants.iter().any(|f| f.flags.contains(FontFlags::MATH));
+            let detail = summarize_font_family(variants);
+            if !equation || is_math {
                 self.str_completion(
                     family,
                     Some(CompletionKind::Font),
@@ -1790,4 +1810,21 @@ mod tests {
             .must_include(["r", "dashed"])
             .must_exclude(["cases"]);
     }
+
+    #[test]
+    fn test_autocomplete_fonts() {
+        test("#text(font:)", -1)
+            .must_include(["\"Libertinus Serif\"", "\"New Computer Modern Math\""]);
+
+        test("#show link: set text(font: )", -1)
+            .must_include(["\"Libertinus Serif\"", "\"New Computer Modern Math\""]);
+
+        test("#show math.equation: set text(font: )", -1)
+            .must_include(["\"New Computer Modern Math\""])
+            .must_exclude(["\"Libertinus Serif\""]);
+
+        test("#show math.equation: it => { set text(font: )\nit }", -6)
+            .must_include(["\"New Computer Modern Math\""])
+            .must_exclude(["\"Libertinus Serif\""]);
+    }
 }

crates/typst-ide/src/jump.rs

@@ -36,7 +36,7 @@ pub fn jump_from_click(
 ) -> Option<Jump> {
     // Try to find a link first.
     for (pos, item) in frame.items() {
-        if let FrameItem::Link(dest, size) = item {
+        if let FrameItem::Link(_, dest, size) = item {
             if is_in_rect(*pos, *size, click) {
                 return Some(match dest {
                     Destination::Url(url) => Jump::Url(url.clone()),

crates/typst-ide/src/tooltip.rs

@@ -269,7 +269,7 @@ fn font_tooltip(world: &dyn IdeWorld, leaf: &LinkedNode) -> Option<Tooltip> {
             .find(|&(family, _)| family.to_lowercase().as_str() == lower.as_str());
 
         then {
-            let detail = summarize_font_family(iter);
+            let detail = summarize_font_family(iter.collect());
             return Some(Tooltip::Text(detail));
         }
     };
@@ -371,4 +371,11 @@ mod tests {
         test(&world, -2, Side::Before).must_be_none();
         test(&world, -2, Side::After).must_be_text("This star imports `a`, `b`, and `c`");
     }
+
+    #[test]
+    fn test_tooltip_field_call() {
+        let world = TestWorld::new("#import \"other.typ\"\n#other.f()")
+            .with_source("other.typ", "#let f = (x) => 1");
+        test(&world, -4, Side::After).must_be_code("(..) => ..");
+    }
 }

crates/typst-ide/src/utils.rs

@@ -77,23 +77,20 @@ pub fn plain_docs_sentence(docs: &str) -> EcoString {
 }
 
 /// Create a short description of a font family.
-pub fn summarize_font_family<'a>(
-    variants: impl Iterator<Item = &'a FontInfo>,
-) -> EcoString {
-    let mut infos: Vec<_> = variants.collect();
-    infos.sort_by_key(|info| info.variant);
+pub fn summarize_font_family(mut variants: Vec<&FontInfo>) -> EcoString {
+    variants.sort_by_key(|info| info.variant);
 
     let mut has_italic = false;
     let mut min_weight = u16::MAX;
     let mut max_weight = 0;
-    for info in &infos {
+    for info in &variants {
         let weight = info.variant.weight.to_number();
         has_italic |= info.variant.style == FontStyle::Italic;
         min_weight = min_weight.min(weight);
         max_weight = min_weight.max(weight);
     }
 
-    let count = infos.len();
+    let count = variants.len();
     let mut detail = eco_format!("{count} variant{}.", if count == 1 { "" } else { "s" });
 
     if min_weight == max_weight {

crates/typst-layout/src/flow/distribute.rs

@@ -93,7 +93,7 @@ impl Item<'_, '_> {
             Self::Frame(frame, _) => {
                 frame.size().is_zero()
                     && frame.items().all(|(_, item)| {
-                        matches!(item, FrameItem::Link(_, _) | FrameItem::Tag(_))
+                        matches!(item, FrameItem::Link(..) | FrameItem::Tag(_))
                     })
             }
             Self::Placed(_, placed) => !placed.float,

crates/typst-layout/src/math/fragment.rs

@@ -11,7 +11,7 @@ use typst_library::layout::{
 };
 use typst_library::math::{EquationElem, MathSize};
 use typst_library::text::{Font, Glyph, Lang, Region, TextElem, TextItem};
-use typst_library::visualize::Paint;
+use typst_library::visualize::{FixedStroke, Paint};
 use typst_syntax::Span;
 use typst_utils::default_math_class;
 use unicode_math_class::MathClass;
@@ -235,6 +235,7 @@ pub struct GlyphFragment {
     pub lang: Lang,
     pub region: Option<Region>,
     pub fill: Paint,
+    pub stroke: Option<FixedStroke>,
     pub shift: Abs,
     pub width: Abs,
     pub ascent: Abs,
@@ -286,6 +287,7 @@ impl GlyphFragment {
             lang: TextElem::lang_in(styles),
             region: TextElem::region_in(styles),
             fill: TextElem::fill_in(styles).as_decoration(),
+            stroke: TextElem::stroke_in(styles).map(|s| s.unwrap_or_default()),
             shift: TextElem::baseline_in(styles),
             font_size: TextElem::size_in(styles),
             math_size: EquationElem::size_in(styles),
@@ -368,10 +370,10 @@ impl GlyphFragment {
             font: self.font.clone(),
             size: self.font_size,
             fill: self.fill,
+            stroke: self.stroke,
             lang: self.lang,
             region: self.region,
             text: self.c.into(),
-            stroke: None,
             glyphs: vec![Glyph {
                 id: self.id.0,
                 x_advance: Em::from_length(self.width, self.font_size),

crates/typst-layout/src/math/run.rs

@@ -278,6 +278,9 @@ impl MathRun {
         frame
     }
 
+    /// Convert this run of math fragments into a vector of inline items for
+    /// paragraph layout. Creates multiple fragments when relation or binary
+    /// operators are present to allow for line-breaking opportunities later.
     pub fn into_par_items(self) -> Vec<InlineItem> {
         let mut items = vec![];
 
@@ -295,22 +298,25 @@ impl MathRun {
 
         let mut space_is_visible = false;
 
-        let is_relation = |f: &MathFragment| matches!(f.class(), MathClass::Relation);
         let is_space = |f: &MathFragment| {
             matches!(f, MathFragment::Space(_) | MathFragment::Spacing(_, _))
         };
+        let is_line_break_opportunity = |class, next_fragment| match class {
+            // Don't split when two relations are in a row or when preceding a
+            // closing parenthesis.
+            MathClass::Binary => next_fragment != Some(MathClass::Closing),
+            MathClass::Relation => {
+                !matches!(next_fragment, Some(MathClass::Relation | MathClass::Closing))
+            }
+            _ => false,
+        };
 
         let mut iter = self.0.into_iter().peekable();
         while let Some(fragment) = iter.next() {
-            if space_is_visible {
-                match fragment {
-                    MathFragment::Space(width) | MathFragment::Spacing(width, _) => {
-                        items.push(InlineItem::Space(width, true));
+            if space_is_visible && is_space(&fragment) {
+                items.push(InlineItem::Space(fragment.width(), true));
                 continue;
             }
-                    _ => {}
-                }
-            }
 
             let class = fragment.class();
             let y = fragment.ascent();
@@ -323,10 +329,9 @@ impl MathRun {
             frame.push_frame(pos, fragment.into_frame());
             empty = false;
 
-            if class == MathClass::Binary
-                || (class == MathClass::Relation
-                    && !iter.peek().map(is_relation).unwrap_or_default())
-            {
+            // Split our current frame when we encounter a binary operator or
+            // relation so that there is a line-breaking opportunity.
+            if is_line_break_opportunity(class, iter.peek().map(|f| f.class())) {
                 let mut frame_prev =
                     std::mem::replace(&mut frame, Frame::soft(Size::zero()));
 

crates/typst-layout/src/modifiers.rs

@@ -1,3 +1,4 @@
+use ecow::EcoString;
 use typst_library::foundations::StyleChain;
 use typst_library::layout::{Abs, Fragment, Frame, FrameItem, HideElem, Point, Sides};
 use typst_library::model::{Destination, LinkElem, ParElem};
@@ -21,6 +22,7 @@ use typst_library::model::{Destination, LinkElem, ParElem};
 pub struct FrameModifiers {
     /// A destination to link to.
     dest: Option<Destination>,
+    alt: Option<EcoString>,
     /// Whether the contents of the frame should be hidden.
     hidden: bool,
 }
@@ -28,8 +30,10 @@ pub struct FrameModifiers {
 impl FrameModifiers {
     /// Retrieve all modifications that should be applied per-frame.
     pub fn get_in(styles: StyleChain) -> Self {
+        // TODO: maybe verify that an alt text was provided here
         Self {
             dest: LinkElem::current_in(styles),
+            alt: LinkElem::alt_in(styles),
             hidden: HideElem::hidden_in(styles),
         }
     }
@@ -102,7 +106,7 @@ fn modify_frame(
             pos.x -= outset.left;
             size += outset.sum_by_axis();
         }
-        frame.push(pos, FrameItem::Link(dest.clone(), size));
+        frame.push(pos, FrameItem::Link(modifiers.alt.clone(), dest.clone(), size));
     }
 
     if modifiers.hidden {

crates/typst-layout/src/pages/run.rs

@@ -185,6 +185,8 @@ fn layout_page_run_impl(
     )?;
 
     // Layouts a single marginal.
+    // TODO: add some sort of tag that indicates the marginals and use it to
+    // mark them as artifacts for PDF/UA.
     let mut layout_marginal = |content: &Option<Content>, area, align| {
         let Some(content) = content else { return Ok(None) };
         let aligned = content.clone().styled(AlignElem::set_alignment(align));

crates/typst-library/src/foundations/content.rs

@@ -503,8 +503,9 @@ impl Content {
     }
 
     /// Link the content somewhere.
-    pub fn linked(self, dest: Destination) -> Self {
-        self.styled(LinkElem::set_current(Some(dest)))
+    pub fn linked(self, alt: Option<EcoString>, dest: Destination) -> Self {
+        self.styled(LinkElem::set_alt(alt))
+            .styled(LinkElem::set_current(Some(dest)))
     }
 
     /// Set alignments for this content.

crates/typst-library/src/html/mod.rs

@@ -7,6 +7,7 @@ pub use self::dom::*;
 use ecow::EcoString;
 
 use crate::foundations::{elem, Content, Module, Scope};
+use crate::introspection::Locatable;
 
 /// Create a module with all HTML definitions.
 pub fn module() -> Module {
@@ -38,7 +39,7 @@ pub fn module() -> Module {
 ///   A div with _Typst content_ inside!
 /// ]
 /// ```
-#[elem(name = "elem")]
+#[elem(name = "elem", Locatable)]
 pub struct HtmlElem {
     /// The element's tag.
     #[required]

crates/typst-library/src/layout/frame.rs

@@ -4,6 +4,7 @@ use std::fmt::{self, Debug, Formatter};
 use std::num::NonZeroUsize;
 use std::sync::Arc;
 
+use ecow::EcoString;
 use typst_syntax::Span;
 use typst_utils::{LazyHash, Numeric};
 
@@ -473,7 +474,7 @@ pub enum FrameItem {
     /// An image and its size.
     Image(Image, Size, Span),
     /// An internal or external link to a destination.
-    Link(Destination, Size),
+    Link(Option<EcoString>, Destination, Size),
     /// An introspectable element that produced something within this frame.
     Tag(Tag),
 }
@@ -485,7 +486,7 @@ impl Debug for FrameItem {
             Self::Text(text) => write!(f, "{text:?}"),
             Self::Shape(shape, _) => write!(f, "{shape:?}"),
             Self::Image(image, _, _) => write!(f, "{image:?}"),
-            Self::Link(dest, _) => write!(f, "Link({dest:?})"),
+            Self::Link(alt, dest, _) => write!(f, "Link({alt:?}, {dest:?})"),
             Self::Tag(tag) => write!(f, "{tag:?}"),
         }
     }

crates/typst-library/src/layout/grid/mod.rs

@@ -13,6 +13,7 @@ use crate::foundations::{
     cast, elem, scope, Array, CastInfo, Content, Context, Fold, FromValue, Func,
     IntoValue, NativeElement, Packed, Reflect, Resolve, Show, Smart, StyleChain, Value,
 };
+use crate::introspection::Locatable;
 use crate::layout::{
     Alignment, BlockElem, Length, OuterHAlignment, OuterVAlignment, Rel, Sides, Sizing,
 };
@@ -136,7 +137,7 @@ use crate::visualize::{Paint, Stroke};
 ///
 /// Furthermore, strokes of a repeated grid header or footer will take
 /// precedence over regular cell strokes.
-#[elem(scope, Show)]
+#[elem(scope, Locatable, Show)]
 pub struct GridElem {
     /// The column sizes.
     ///
@@ -462,7 +463,7 @@ impl TryFrom<Content> for GridItem {
 /// If `repeat` is set to `true`, the header will be repeated across pages. For
 /// an example, refer to the [`table.header`]($table.header) element and the
 /// [`grid.stroke`]($grid.stroke) parameter.
-#[elem(name = "header", title = "Grid Header")]
+#[elem(name = "header", title = "Grid Header", Locatable)]
 pub struct GridHeader {
     /// Whether this header should be repeated across pages.
     #[default(true)]
@@ -479,7 +480,7 @@ pub struct GridHeader {
 /// itself on every page of the table.
 ///
 /// No other grid cells may be placed after the footer.
-#[elem(name = "footer", title = "Grid Footer")]
+#[elem(name = "footer", title = "Grid Footer", Locatable)]
 pub struct GridFooter {
     /// Whether this footer should be repeated across pages.
     #[default(true)]
@@ -646,7 +647,7 @@ pub struct GridVLine {
 /// which allows you, for example, to apply styles based on a cell's position.
 /// Refer to the examples of the [`table.cell`]($table.cell) element to learn
 /// more about this.
-#[elem(name = "cell", title = "Grid Cell", Show)]
+#[elem(name = "cell", title = "Grid Cell", Locatable, Show)]
 pub struct GridCell {
     /// The cell's body.
     #[required]

crates/typst-library/src/layout/hide.rs

@@ -1,6 +1,7 @@
 use crate::diag::SourceResult;
 use crate::engine::Engine;
 use crate::foundations::{elem, Content, Packed, Show, StyleChain};
+use crate::introspection::Locatable;
 
 /// Hides content without affecting layout.
 ///
@@ -14,7 +15,7 @@ use crate::foundations::{elem, Content, Packed, Show, StyleChain};
 /// Hello Jane \
 /// #hide[Hello] Joe
 /// ```
-#[elem(Show)]
+#[elem(Locatable, Show)]
 pub struct HideElem {
     /// The content to hide.
     #[required]

crates/typst-library/src/layout/layout.rs

@@ -41,8 +41,23 @@ use crate::layout::{BlockElem, Size};
 /// receives the page's dimensions minus its margins. This is mostly useful in
 /// combination with [measurement]($measure).
 ///
-/// You can also use this function to resolve [`ratio`] to fixed lengths. This
-/// might come in handy if you're building your own layout abstractions.
+/// To retrieve the _remaining_ size of the page rather than its full size, you
+/// you can wrap your `layout` call in a `{block(height: 1fr)}`. This works
+/// because the block automatically grows to fill the remaining space (see the
+/// [fraction] documentation for more details).
+///
+/// ```example
+/// #set page(height: 150pt)
+///
+/// #lorem(20)
+///
+/// #block(height: 1fr, layout(size => [
+///   Remaining height: #size.height
+/// ]))
+/// ```
+///
+/// You can also use this function to resolve a [`ratio`] to a fixed length.
+/// This might come in handy if you're building your own layout abstractions.
 ///
 /// ```example
 /// #layout(size => {

crates/typst-library/src/layout/repeat.rs

@@ -1,6 +1,7 @@
 use crate::diag::SourceResult;
 use crate::engine::Engine;
 use crate::foundations::{elem, Content, NativeElement, Packed, Show, StyleChain};
+use crate::introspection::Locatable;
 use crate::layout::{BlockElem, Length};
 
 /// Repeats content to the available space.
@@ -24,7 +25,7 @@ use crate::layout::{BlockElem, Length};
 ///   Berlin, the 22nd of December, 2022
 /// ]
 /// ```
-#[elem(Show)]
+#[elem(Locatable, Show)]
 pub struct RepeatElem {
     /// The content to repeat.
     #[required]

crates/typst-library/src/math/mod.rs

@@ -28,6 +28,7 @@ use typst_utils::singleton;
 use unicode_math_class::MathClass;
 
 use crate::foundations::{elem, Content, Module, NativeElement, Scope};
+use crate::introspection::Locatable;
 use crate::layout::{Em, HElem};
 use crate::text::TextElem;
 
@@ -109,7 +110,7 @@ pub fn module() -> Module {
 pub trait Mathy {}
 
 /// A math alignment point: `&`, `&&`.
-#[elem(title = "Alignment Point", Mathy)]
+#[elem(title = "Alignment Point", Mathy, Locatable)]
 pub struct AlignPointElem {}
 
 impl AlignPointElem {
@@ -136,7 +137,7 @@ impl AlignPointElem {
 ///
 /// $x loves y and y loves 5$
 /// ```
-#[elem(Mathy)]
+#[elem(Mathy, Locatable)]
 pub struct ClassElem {
     /// The class to apply to the content.
     #[required]

crates/typst-library/src/math/root.rs

@@ -1,6 +1,7 @@
 use typst_syntax::Span;
 
 use crate::foundations::{elem, func, Content, NativeElement};
+use crate::introspection::Locatable;
 use crate::math::Mathy;
 
 /// A square root.
@@ -22,7 +23,7 @@ pub fn sqrt(
 /// ```example
 /// $ root(3, x) $
 /// ```
-#[elem(Mathy)]
+#[elem(Mathy, Locatable)]
 pub struct RootElem {
     /// Which root of the radicand to take.
     #[positional]

crates/typst-library/src/model/bibliography.rs

@@ -852,7 +852,8 @@ impl<'a> Generator<'a> {
                         renderer.display_elem_child(elem, &mut None, false)?;
                     if let Some(location) = first_occurrences.get(item.key.as_str()) {
                         let dest = Destination::Location(*location);
-                        content = content.linked(dest);
+                        // TODO: accept user supplied alt text
+                        content = content.linked(None, dest);
                     }
                     StrResult::Ok(content)
                 })
@@ -987,7 +988,8 @@ impl ElemRenderer<'_> {
         if let Some(hayagriva::ElemMeta::Entry(i)) = elem.meta {
             if let Some(location) = (self.link)(i) {
                 let dest = Destination::Location(location);
-                content = content.linked(dest);
+                // TODO: accept user supplied alt text
+                content = content.linked(None, dest);
             }
         }
 

crates/typst-library/src/model/cite.rs

@@ -43,7 +43,7 @@ use crate::text::{Lang, Region, TextElem};
 /// This function indirectly has dedicated syntax. [References]($ref) can be
 /// used to cite works from the bibliography. The label then corresponds to the
 /// citation key.
-#[elem(Synthesize)]
+#[elem(Locatable, Synthesize)]
 pub struct CiteElem {
     /// The citation key that identifies the entry in the bibliography that
     /// shall be cited, as a label.

crates/typst-library/src/model/emph.rs

@@ -4,6 +4,7 @@ use crate::foundations::{
     elem, Content, NativeElement, Packed, Show, StyleChain, TargetElem,
 };
 use crate::html::{tag, HtmlElem};
+use crate::introspection::Locatable;
 use crate::text::{ItalicToggle, TextElem};
 
 /// Emphasizes content by toggling italics.
@@ -29,7 +30,7 @@ use crate::text::{ItalicToggle, TextElem};
 /// This function also has dedicated syntax: To emphasize content, simply
 /// enclose it in underscores (`_`). Note that this only works at word
 /// boundaries. To emphasize part of a word, you have to use the function.
-#[elem(title = "Emphasis", keywords = ["italic"], Show)]
+#[elem(title = "Emphasis", keywords = ["italic"], Locatable, Show)]
 pub struct EmphElem {
     /// The content to emphasize.
     #[required]

crates/typst-library/src/model/enum.rs

@@ -10,6 +10,7 @@ use crate::foundations::{
     Styles, TargetElem,
 };
 use crate::html::{attr, tag, HtmlElem};
+use crate::introspection::Locatable;
 use crate::layout::{Alignment, BlockElem, Em, HAlignment, Length, VAlignment, VElem};
 use crate::model::{
     ListItemLike, ListLike, Numbering, NumberingPattern, ParElem, ParbreakElem,
@@ -71,7 +72,7 @@ use crate::model::{
 /// Enumeration items can contain multiple paragraphs and other block-level
 /// content. All content that is indented more than an item's marker becomes
 /// part of that item.
-#[elem(scope, title = "Numbered List", Show)]
+#[elem(scope, title = "Numbered List", Locatable, Show)]
 pub struct EnumElem {
     /// Defines the default [spacing]($enum.spacing) of the enumeration. If it
     /// is `{false}`, the items are spaced apart with
@@ -271,7 +272,7 @@ impl Show for Packed<EnumElem> {
 }
 
 /// An enumeration item.
-#[elem(name = "item", title = "Numbered List Item")]
+#[elem(name = "item", title = "Numbered List Item", Locatable)]
 pub struct EnumItem {
     /// The item's number.
     #[positional]

crates/typst-library/src/model/figure.rs

@@ -470,7 +470,7 @@ impl Outlinable for Packed<FigureElem> {
 ///   caption: [A rectangle],
 /// )
 /// ```
-#[elem(name = "caption", Synthesize, Show)]
+#[elem(name = "caption", Locatable, Synthesize, Show)]
 pub struct FigureCaption {
     /// The caption's position in the figure. Either `{top}` or `{bottom}`.
     ///

crates/typst-library/src/model/footnote.rs

@@ -147,7 +147,8 @@ impl Show for Packed<FootnoteElem> {
         let sup = SuperElem::new(num).pack().spanned(span);
         let loc = loc.variant(1);
         // Add zero-width weak spacing to make the footnote "sticky".
-        Ok(HElem::hole().pack() + sup.linked(Destination::Location(loc)))
+        // TODO: accept user supplied alt text
+        Ok(HElem::hole().pack() + sup.linked(None, Destination::Location(loc)))
     }
 }
 
@@ -192,7 +193,7 @@ cast! {
 /// page run is a sequence of pages without an explicit pagebreak in between).
 /// For this reason, set and show rules for footnote entries should be defined
 /// before any page content, typically at the very start of the document.
-#[elem(name = "entry", title = "Footnote Entry", Show, ShowSet)]
+#[elem(name = "entry", title = "Footnote Entry", Locatable, Show, ShowSet)]
 pub struct FootnoteEntry {
     /// The footnote for this entry. Its location can be used to determine
     /// the footnote counter state.
@@ -296,7 +297,8 @@ impl Show for Packed<FootnoteEntry> {
         let sup = SuperElem::new(num)
             .pack()
             .spanned(span)
-            .linked(Destination::Location(loc))
+            // TODO: accept user supplied alt text
+            .linked(None, Destination::Location(loc))
             .located(loc.variant(1));
 
         Ok(Content::sequence([

crates/typst-library/src/model/link.rs

@@ -9,7 +9,7 @@ use crate::foundations::{
     StyleChain, Styles, TargetElem,
 };
 use crate::html::{attr, tag, HtmlElem};
-use crate::introspection::Location;
+use crate::introspection::{Locatable, Location};
 use crate::layout::Position;
 use crate::text::TextElem;
 
@@ -38,8 +38,11 @@ use crate::text::TextElem;
 /// # Syntax
 /// This function also has dedicated syntax: Text that starts with `http://` or
 /// `https://` is automatically turned into a link.
-#[elem(Show)]
+#[elem(Locatable, Show)]
 pub struct LinkElem {
+    /// A text describing the link.
+    pub alt: Option<EcoString>,
+
     /// The destination the link points to.
     ///
     /// - To link to web pages, `dest` should be a valid URL string. If the URL
@@ -123,12 +126,13 @@ impl Show for Packed<LinkElem> {
                 body
             }
         } else {
+            let alt = self.alt(styles);
             match &self.dest {
-                LinkTarget::Dest(dest) => body.linked(dest.clone()),
+                LinkTarget::Dest(dest) => body.linked(alt, dest.clone()),
                 LinkTarget::Label(label) => {
                     let elem = engine.introspector.query_label(*label).at(self.span())?;
                     let dest = Destination::Location(elem.location().unwrap());
-                    body.clone().linked(dest)
+                    body.clone().linked(alt, dest)
                 }
             }
         })

crates/typst-library/src/model/list.rs

@@ -7,6 +7,7 @@ use crate::foundations::{
     Smart, StyleChain, Styles, TargetElem, Value,
 };
 use crate::html::{tag, HtmlElem};
+use crate::introspection::Locatable;
 use crate::layout::{BlockElem, Em, Length, VElem};
 use crate::model::{ParElem, ParbreakElem};
 use crate::text::TextElem;
@@ -42,7 +43,7 @@ use crate::text::TextElem;
 /// followed by a space to create a list item. A list item can contain multiple
 /// paragraphs and other block-level content. All content that is indented
 /// more than an item's marker becomes part of that item.
-#[elem(scope, title = "Bullet List", Show)]
+#[elem(scope, title = "Bullet List", Locatable, Show)]
 pub struct ListElem {
     /// Defines the default [spacing]($list.spacing) of the list. If it is
     /// `{false}`, the items are spaced apart with
@@ -178,7 +179,7 @@ impl Show for Packed<ListElem> {
 }
 
 /// A bullet list item.
-#[elem(name = "item", title = "Bullet List Item")]
+#[elem(name = "item", title = "Bullet List Item", Locatable)]
 pub struct ListItem {
     /// The item's body.
     #[required]

crates/typst-library/src/model/outline.rs

@@ -2,6 +2,7 @@ use std::num::NonZeroUsize;
 use std::str::FromStr;
 
 use comemo::{Track, Tracked};
+use ecow::eco_format;
 use smallvec::SmallVec;
 use typst_syntax::Span;
 use typst_utils::{Get, NonZeroExt};
@@ -17,8 +18,7 @@ use crate::introspection::{
     Counter, CounterKey, Introspector, Locatable, Location, Locator, LocatorLink,
 };
 use crate::layout::{
-    Abs, Axes, BlockBody, BlockElem, BoxElem, Dir, Em, Fr, HElem, Length, Region, Rel,
-    RepeatElem, Sides,
+    Abs, Axes, BlockBody, BlockElem, BoxElem, Dir, Em, Fr, HElem, Length, PageElem, Region, Rel, RepeatElem, Sides
 };
 use crate::math::EquationElem;
 use crate::model::{Destination, HeadingElem, NumberingPattern, ParElem, Refable};
@@ -368,7 +368,7 @@ pub trait Outlinable: Refable {
 /// With show-set and show rules on outline entries, you can richly customize
 /// the outline's appearance. See the
 /// [section on styling the outline]($outline/#styling-the-outline) for details.
-#[elem(scope, name = "entry", title = "Outline Entry", Show)]
+#[elem(scope, name = "entry", title = "Outline Entry", Locatable, Show)]
 pub struct OutlineEntry {
     /// The nesting level of this outline entry. Starts at `{1}` for top-level
     /// entries.
@@ -422,7 +422,17 @@ impl Show for Packed<OutlineEntry> {
         let context = context.track();
 
         let prefix = self.prefix(engine, context, span)?;
-        let inner = self.inner(engine, context, span)?;
+        let body = self.body().at(span)?;
+        let page = self.page(engine, context, span)?;
+        let alt = {
+            // TODO: accept user supplied alt text
+            let prefix = prefix.as_ref().map(|p| p.plain_text()).unwrap_or_default();
+            let body = body.plain_text();
+            let page_str = PageElem::local_name_in(styles);
+            let page_nr = page.plain_text();
+            eco_format!("{prefix} {body} {page_str} {page_nr}")
+        };
+        let inner = self.inner(engine, context, span, body, page)?;
         let block = if self.element.is::<EquationElem>() {
             let body = prefix.unwrap_or_default() + inner;
             BlockElem::new()
@@ -434,7 +444,7 @@ impl Show for Packed<OutlineEntry> {
         };
 
         let loc = self.element_location().at(span)?;
-        Ok(block.linked(Destination::Location(loc)))
+        Ok(block.linked(Some(alt), Destination::Location(loc)))
     }
 }
 
@@ -571,6 +581,8 @@ impl OutlineEntry {
         engine: &mut Engine,
         context: Tracked<Context>,
         span: Span,
+        body: Content,
+        page: Content,
     ) -> SourceResult<Content> {
         let styles = context.styles().at(span)?;
 
@@ -591,7 +603,7 @@ impl OutlineEntry {
             seq.push(TextElem::packed("\u{202B}"));
         }
 
-        seq.push(self.body().at(span)?);
+        seq.push(body);
 
         if rtl {
             // "Pop Directional Formatting"
@@ -616,7 +628,7 @@ impl OutlineEntry {
         // Add the page number. The word joiner in front ensures that the page
         // number doesn't stand alone in its line.
         seq.push(TextElem::packed("\u{2060}"));
-        seq.push(self.page(engine, context, span)?);
+        seq.push(page);
 
         Ok(Content::sequence(seq))
     }

crates/typst-library/src/model/par.rs

@@ -93,7 +93,7 @@ use crate::model::Numbering;
 /// let $a$ be the smallest of the
 /// three integers. Then, we ...
 /// ```
-#[elem(scope, title = "Paragraph")]
+#[elem(scope, title = "Paragraph", Locatable)]
 pub struct ParElem {
     /// The spacing between lines.
     ///

crates/typst-library/src/model/reference.rs

@@ -21,9 +21,10 @@ use crate::text::TextElem;
 ///
 /// The default, a `{"normal"}` reference, produces a textual reference to a
 /// label. For example, a reference to a heading will yield an appropriate
-/// string such as "Section 1" for a reference to the first heading. The
-/// references are also links to the respective element. Reference syntax can
-/// also be used to [cite] from a bibliography.
+/// string such as "Section 1" for a reference to the first heading. The word
+/// "Section" depends on the [`lang`]($text.lang) setting and is localized
+/// accordingly. The references are also links to the respective element.
+/// Reference syntax can also be used to [cite] from a bibliography.
 ///
 /// As the default form requires a supplement and numbering, the label must be
 /// attached to a _referenceable element_. Referenceable elements include
@@ -308,7 +309,8 @@ fn show_reference(
         content = supplement + TextElem::packed("\u{a0}") + content;
     }
 
-    Ok(content.linked(Destination::Location(loc)))
+    // TODO: accept user supplied alt text
+    Ok(content.linked(None, Destination::Location(loc)))
 }
 
 /// Turn a reference into a citation.

crates/typst-library/src/model/strong.rs

@@ -4,6 +4,7 @@ use crate::foundations::{
     elem, Content, NativeElement, Packed, Show, StyleChain, TargetElem,
 };
 use crate::html::{tag, HtmlElem};
+use crate::introspection::Locatable;
 use crate::text::{TextElem, WeightDelta};
 
 /// Strongly emphasizes content by increasing the font weight.
@@ -24,7 +25,7 @@ use crate::text::{TextElem, WeightDelta};
 /// simply enclose it in stars/asterisks (`*`). Note that this only works at
 /// word boundaries. To strongly emphasize part of a word, you have to use the
 /// function.
-#[elem(title = "Strong Emphasis", keywords = ["bold", "weight"], Show)]
+#[elem(title = "Strong Emphasis", keywords = ["bold", "weight"], Locatable, Show)]
 pub struct StrongElem {
     /// The delta to apply on the font weight.
     ///

crates/typst-library/src/model/table.rs

@@ -10,7 +10,7 @@ use crate::foundations::{
     TargetElem,
 };
 use crate::html::{attr, tag, HtmlAttrs, HtmlElem, HtmlTag};
-use crate::introspection::Locator;
+use crate::introspection::{Locatable, Locator};
 use crate::layout::grid::resolve::{table_to_cellgrid, Cell, CellGrid, Entry};
 use crate::layout::{
     show_grid_cell, Abs, Alignment, BlockElem, Celled, GridCell, GridFooter, GridHLine,
@@ -121,7 +121,7 @@ use crate::visualize::{Paint, Stroke};
 ///   [Robert], b, a, b,
 /// )
 /// ```
-#[elem(scope, Show, LocalName, Figurable)]
+#[elem(scope, Locatable, Show, LocalName, Figurable)]
 pub struct TableElem {
     /// The column sizes. See the [grid documentation]($grid) for more
     /// information on track sizing.
@@ -486,7 +486,7 @@ impl TryFrom<Content> for TableItem {
 ///   [7.34], [57],  [2],
 /// )
 /// ```
-#[elem(name = "header", title = "Table Header")]
+#[elem(name = "header", title = "Table Header", Locatable)]
 pub struct TableHeader {
     /// Whether this header should be repeated across pages.
     #[default(true)]
@@ -505,7 +505,7 @@ pub struct TableHeader {
 /// totals, or other information that should be visible on every page.
 ///
 /// No other table cells may be placed after the footer.
-#[elem(name = "footer", title = "Table Footer")]
+#[elem(name = "footer", title = "Table Footer", Locatable)]
 pub struct TableFooter {
     /// Whether this footer should be repeated across pages.
     #[default(true)]
@@ -548,7 +548,7 @@ pub struct TableFooter {
 ///   [19:00], [Day 1 Attendee Mixer],
 /// )
 /// ```
-#[elem(name = "hline", title = "Table Horizontal Line")]
+#[elem(name = "hline", title = "Table Horizontal Line", Locatable)]
 pub struct TableHLine {
     /// The row above which the horizontal line is placed (zero-indexed).
     /// Functions identically to the `y` field in [`grid.hline`]($grid.hline.y).
@@ -593,7 +593,7 @@ pub struct TableHLine {
 /// use the [table's `stroke`]($table.stroke) field or [`table.cell`'s
 /// `stroke`]($table.cell.stroke) field instead if the line you want to place is
 /// part of all your tables' designs.
-#[elem(name = "vline", title = "Table Vertical Line")]
+#[elem(name = "vline", title = "Table Vertical Line", Locatable)]
 pub struct TableVLine {
     /// The column before which the horizontal line is placed (zero-indexed).
     /// Functions identically to the `x` field in [`grid.vline`]($grid.vline).
@@ -714,7 +714,7 @@ pub struct TableVLine {
 ///   [Vikram], [49], [Perseverance],
 /// )
 /// ```
-#[elem(name = "cell", title = "Table Cell", Show)]
+#[elem(name = "cell", title = "Table Cell", Locatable, Show)]
 pub struct TableCell {
     /// The cell's body.
     #[required]

crates/typst-library/src/model/terms.rs

@@ -7,6 +7,7 @@ use crate::foundations::{
     Styles, TargetElem,
 };
 use crate::html::{tag, HtmlElem};
+use crate::introspection::Locatable;
 use crate::layout::{Em, HElem, Length, Sides, StackChild, StackElem, VElem};
 use crate::model::{ListItemLike, ListLike, ParElem, ParbreakElem};
 use crate::text::TextElem;
@@ -27,7 +28,7 @@ use crate::text::TextElem;
 /// # Syntax
 /// This function also has dedicated syntax: Starting a line with a slash,
 /// followed by a term, a colon and a description creates a term list item.
-#[elem(scope, title = "Term List", Show)]
+#[elem(scope, title = "Term List", Locatable, Show)]
 pub struct TermsElem {
     /// Defines the default [spacing]($terms.spacing) of the term list. If it is
     /// `{false}`, the items are spaced apart with
@@ -205,7 +206,7 @@ impl Show for Packed<TermsElem> {
 }
 
 /// A term list item.
-#[elem(name = "item", title = "Term List Item")]
+#[elem(name = "item", title = "Term List Item", Locatable)]
 pub struct TermItem {
     /// The term described by the list item.
     #[required]

crates/typst-library/src/text/deco.rs

@@ -3,6 +3,7 @@ use smallvec::smallvec;
 use crate::diag::SourceResult;
 use crate::engine::Engine;
 use crate::foundations::{elem, Content, Packed, Show, Smart, StyleChain};
+use crate::introspection::Locatable;
 use crate::layout::{Abs, Corners, Length, Rel, Sides};
 use crate::text::{BottomEdge, BottomEdgeMetric, TextElem, TopEdge, TopEdgeMetric};
 use crate::visualize::{Color, FixedStroke, Paint, Stroke};
@@ -13,7 +14,7 @@ use crate::visualize::{Color, FixedStroke, Paint, Stroke};
 /// ```example
 /// This is #underline[important].
 /// ```
-#[elem(Show)]
+#[elem(Locatable, Show)]
 pub struct UnderlineElem {
     /// How to [stroke] the line.
     ///
@@ -99,7 +100,7 @@ impl Show for Packed<UnderlineElem> {
 /// ```example
 /// #overline[A line over text.]
 /// ```
-#[elem(Show)]
+#[elem(Locatable, Show)]
 pub struct OverlineElem {
     /// How to [stroke] the line.
     ///
@@ -191,7 +192,7 @@ impl Show for Packed<OverlineElem> {
 /// ```example
 /// This is #strike[not] relevant.
 /// ```
-#[elem(title = "Strikethrough", Show)]
+#[elem(title = "Strikethrough", Locatable, Show)]
 pub struct StrikeElem {
     /// How to [stroke] the line.
     ///
@@ -268,7 +269,7 @@ impl Show for Packed<StrikeElem> {
 /// ```example
 /// This is #highlight[important].
 /// ```
-#[elem(Show)]
+#[elem(Locatable, Show)]
 pub struct HighlightElem {
     /// The color to highlight the text with.
     ///

crates/typst-library/src/text/font/book.rs

@@ -194,6 +194,8 @@ bitflags::bitflags! {
         const MONOSPACE = 1 << 0;
         /// Glyphs have short strokes at their stems.
         const SERIF = 1 << 1;
+        /// Font face has a MATH table
+        const MATH = 1 << 2;
     }
 }
 
@@ -272,6 +274,7 @@ impl FontInfo {
 
         let mut flags = FontFlags::empty();
         flags.set(FontFlags::MONOSPACE, ttf.is_monospaced());
+        flags.set(FontFlags::MATH, ttf.tables().math.is_some());
 
         // Determine whether this is a serif or sans-serif font.
         if let Some(panose) = ttf

crates/typst-library/src/text/raw.rs

@@ -18,6 +18,7 @@ use crate::foundations::{
     PlainText, Show, ShowSet, Smart, StyleChain, Styles, Synthesize, TargetElem,
 };
 use crate::html::{tag, HtmlElem};
+use crate::introspection::Locatable;
 use crate::layout::{BlockBody, BlockElem, Em, HAlignment};
 use crate::loading::{DataSource, Load};
 use crate::model::{Figurable, ParElem};
@@ -76,6 +77,7 @@ use crate::World;
     scope,
     title = "Raw Text / Code",
     Synthesize,
+    Locatable,
     Show,
     ShowSet,
     LocalName,
@@ -619,7 +621,7 @@ impl RawTheme {
 /// It allows you to access various properties of the line, such as the line
 /// number, the raw non-highlighted text, the highlighted text, and whether it
 /// is the first or last line of the raw block.
-#[elem(name = "line", title = "Raw Text / Code Line", Show, PlainText)]
+#[elem(name = "line", title = "Raw Text / Code Line", Locatable, Show, PlainText)]
 pub struct RawLine {
     /// The line number of the raw line inside of the raw block, starts at 1.
     #[required]

crates/typst-library/src/text/shift.rs

@@ -3,6 +3,7 @@ use ecow::EcoString;
 use crate::diag::SourceResult;
 use crate::engine::Engine;
 use crate::foundations::{elem, Content, Packed, SequenceElem, Show, StyleChain};
+use crate::introspection::Locatable;
 use crate::layout::{Em, Length};
 use crate::text::{variant, SpaceElem, TextElem, TextSize};
 use crate::World;
@@ -15,7 +16,7 @@ use crate::World;
 /// ```example
 /// Revenue#sub[yearly]
 /// ```
-#[elem(title = "Subscript", Show)]
+#[elem(title = "Subscript", Locatable, Show)]
 pub struct SubElem {
     /// Whether to prefer the dedicated subscript characters of the font.
     ///
@@ -74,7 +75,7 @@ impl Show for Packed<SubElem> {
 /// ```example
 /// 1#super[st] try!
 /// ```
-#[elem(title = "Superscript", Show)]
+#[elem(title = "Superscript", Locatable, Show)]
 pub struct SuperElem {
     /// Whether to prefer the dedicated superscript characters of the font.
     ///

crates/typst-library/src/visualize/image/mod.rs

@@ -21,6 +21,7 @@ use crate::foundations::{
     cast, elem, func, scope, Bytes, Cast, Content, Derived, NativeElement, Packed, Show,
     Smart, StyleChain,
 };
+use crate::introspection::Locatable;
 use crate::layout::{BlockElem, Length, Rel, Sizing};
 use crate::loading::{DataSource, Load, Readable};
 use crate::model::Figurable;
@@ -44,7 +45,7 @@ use crate::text::LocalName;
 ///   ],
 /// )
 /// ```
-#[elem(scope, Show, LocalName, Figurable)]
+#[elem(scope, Locatable, Show, LocalName, Figurable)]
 pub struct ImageElem {
     /// A [path]($syntax/#paths) to an image file or raw bytes making up an
     /// image in one of the supported [formats]($image.format).

crates/typst-pdf/src/convert.rs

@@ -1,7 +1,7 @@
 use std::collections::{BTreeMap, HashMap, HashSet};
 use std::num::NonZeroU64;
 
-use ecow::{eco_format, EcoVec};
+use ecow::{eco_format, EcoString, EcoVec};
 use krilla::annotation::Annotation;
 use krilla::configure::{Configuration, ValidationError, Validator};
 use krilla::destination::{NamedDestination, XyzDestination};
@@ -10,11 +10,12 @@ use krilla::error::KrillaError;
 use krilla::geom::PathBuilder;
 use krilla::page::{PageLabel, PageSettings};
 use krilla::surface::Surface;
+use krilla::tagging::{ArtifactType, ContentTag, Node};
 use krilla::{Document, SerializeSettings};
 use krilla_svg::render_svg_glyph;
 use typst_library::diag::{bail, error, SourceDiagnostic, SourceResult};
 use typst_library::foundations::NativeElement;
-use typst_library::introspection::Location;
+use typst_library::introspection::{self, Location};
 use typst_library::layout::{
     Abs, Frame, FrameItem, GroupItem, PagedDocument, Size, Transform,
 };
@@ -30,6 +31,7 @@ use crate::metadata::build_metadata;
 use crate::outline::build_outline;
 use crate::page::PageLabelExt;
 use crate::shape::handle_shape;
+use crate::tags::{handle_close_tag, handle_open_tag, Placeholder, TagNode, Tags};
 use crate::text::handle_text;
 use crate::util::{convert_path, display_font, AbsExt, TransformExt};
 use crate::PdfOptions;
@@ -39,14 +41,19 @@ pub fn convert(
     typst_document: &PagedDocument,
     options: &PdfOptions,
 ) -> SourceResult<Vec<u8>> {
+    // HACK
+    // let config = Configuration::new();
+    let config = Configuration::new_with_validator(Validator::UA1);
     let settings = SerializeSettings {
         compress_content_streams: true,
         no_device_cs: true,
         ascii_compatible: false,
         xmp_metadata: true,
         cmyk_profile: None,
-        configuration: options.standards.config,
-        enable_tagging: false,
+        configuration: config,
+        // TODO: Should we just set this to false? If set to `false` this will
+        // automatically be enabled if the `UA1` validator is used.
+        enable_tagging: true,
         render_svg_glyph_fn: render_svg_glyph,
     };
 
@@ -54,6 +61,7 @@ pub fn convert(
     let page_index_converter = PageIndexConverter::new(typst_document, options);
     let named_destinations =
         collect_named_destinations(typst_document, &page_index_converter);
+
     let mut gc = GlobalContext::new(
         typst_document,
         options,
@@ -66,6 +74,7 @@ pub fn convert(
 
     document.set_outline(build_outline(&gc));
     document.set_metadata(build_metadata(&gc));
+    document.set_tag_tree(gc.tags.build_tree());
 
     finish(document, gc, options.standards.config)
 }
@@ -105,6 +114,19 @@ fn convert_pages(gc: &mut GlobalContext, document: &mut Document) -> SourceResul
             let mut surface = page.surface();
             let mut fc = FrameContext::new(typst_page.frame.size());
 
+            // Marked-content may not cross page boundaries: reopen tag
+            // that was closed at the end of the last page.
+            if let Some((_, _, nodes)) = gc.tags.stack.last_mut() {
+                let tag = if gc.tags.in_artifact {
+                    ContentTag::Artifact(ArtifactType::Other)
+                } else {
+                    ContentTag::Other
+                };
+                // TODO: somehow avoid empty marked-content sequences
+                let id = surface.start_tagged(tag);
+                nodes.push(TagNode::Leaf(id));
+            }
+
             handle_frame(
                 &mut fc,
                 &typst_page.frame,
@@ -113,10 +135,16 @@ fn convert_pages(gc: &mut GlobalContext, document: &mut Document) -> SourceResul
                 gc,
             )?;
 
+            // Marked-content may not cross page boundaries: close open tag.
+            if !gc.tags.stack.is_empty() {
+                surface.end_tagged();
+            }
+
             surface.finish();
 
-            for annotation in fc.annotations {
-                page.add_annotation(annotation);
+            for (placeholder, annotation) in fc.annotations {
+                let annotation_id = page.add_tagged_annotation(annotation);
+                gc.tags.init_placeholder(placeholder, Node::Leaf(annotation_id));
             }
         }
     }
@@ -171,7 +199,7 @@ impl State {
 /// Context needed for converting a single frame.
 pub(crate) struct FrameContext {
     states: Vec<State>,
-    annotations: Vec<Annotation>,
+    annotations: Vec<(Placeholder, Annotation)>,
 }
 
 impl FrameContext {
@@ -198,8 +226,12 @@ impl FrameContext {
         self.states.last_mut().unwrap()
     }
 
-    pub(crate) fn push_annotation(&mut self, annotation: Annotation) {
-        self.annotations.push(annotation);
+    pub(crate) fn push_annotation(
+        &mut self,
+        placeholder: Placeholder,
+        annotation: Annotation,
+    ) {
+        self.annotations.push((placeholder, annotation));
     }
 }
 
@@ -225,6 +257,8 @@ pub(crate) struct GlobalContext<'a> {
     /// The languages used throughout the document.
     pub(crate) languages: BTreeMap<Lang, usize>,
     pub(crate) page_index_converter: PageIndexConverter,
+    /// Tagged PDF context.
+    pub(crate) tags: Tags,
 }
 
 impl<'a> GlobalContext<'a> {
@@ -244,6 +278,8 @@ impl<'a> GlobalContext<'a> {
             image_spans: HashSet::new(),
             languages: BTreeMap::new(),
             page_index_converter,
+
+            tags: Tags::new(),
         }
     }
 }
@@ -278,8 +314,15 @@ pub(crate) fn handle_frame(
             FrameItem::Image(image, size, span) => {
                 handle_image(gc, fc, image, *size, surface, *span)?
             }
-            FrameItem::Link(d, s) => handle_link(fc, gc, d, *s),
-            FrameItem::Tag(_) => {}
+            FrameItem::Link(alt, dest, size) => {
+                handle_link(fc, gc, alt.as_ref().map(EcoString::to_string), dest, *size)
+            }
+            FrameItem::Tag(introspection::Tag::Start(elem)) => {
+                handle_open_tag(gc, surface, elem)
+            }
+            FrameItem::Tag(introspection::Tag::End(loc, _)) => {
+                handle_close_tag(gc, surface, loc);
+            }
         }
 
         fc.pop();

crates/typst-pdf/src/lib.rs

@@ -9,6 +9,7 @@ mod outline;
 mod page;
 mod paint;
 mod shape;
+mod tags;
 mod text;
 mod util;
 

crates/typst-pdf/src/link.rs

@@ -1,16 +1,18 @@
 use krilla::action::{Action, LinkAction};
-use krilla::annotation::{LinkAnnotation, Target};
+use krilla::annotation::{Annotation, LinkAnnotation, Target};
 use krilla::destination::XyzDestination;
 use krilla::geom::Rect;
-use typst_library::layout::{Abs, Point, Size};
+use typst_library::layout::{Abs, Point, Position, Size};
 use typst_library::model::Destination;
 
 use crate::convert::{FrameContext, GlobalContext};
+use crate::tags::TagNode;
 use crate::util::{AbsExt, PointExt};
 
 pub(crate) fn handle_link(
     fc: &mut FrameContext,
     gc: &mut GlobalContext,
+    alt: Option<String>,
     dest: &Destination,
     size: Size,
 ) {
@@ -44,51 +46,42 @@ pub(crate) fn handle_link(
 
     // TODO: Support quad points.
 
-    let pos = match dest {
+    let target = match dest {
         Destination::Url(u) => {
-            fc.push_annotation(
-                LinkAnnotation::new(
-                    rect,
-                    None,
-                    Target::Action(Action::Link(LinkAction::new(u.to_string()))),
-                )
-                .into(),
-            );
-            return;
+            Target::Action(Action::Link(LinkAction::new(u.to_string())))
         }
-        Destination::Position(p) => *p,
+        Destination::Position(p) => match pos_to_target(gc, *p) {
+            Some(target) => target,
+            None => return,
+        },
         Destination::Location(loc) => {
             if let Some(nd) = gc.loc_to_names.get(loc) {
                 // If a named destination has been registered, it's already guaranteed to
                 // not point to an excluded page.
-                fc.push_annotation(
-                    LinkAnnotation::new(
-                        rect,
-                        None,
-                        Target::Destination(krilla::destination::Destination::Named(
-                            nd.clone(),
-                        )),
-                    )
-                    .into(),
-                );
-                return;
+                Target::Destination(krilla::destination::Destination::Named(nd.clone()))
             } else {
-                gc.document.introspector.position(*loc)
+                let pos = gc.document.introspector.position(*loc);
+                match pos_to_target(gc, pos) {
+                    Some(target) => target,
+                    None => return,
+                }
             }
         }
     };
 
-    let page_index = pos.page.get() - 1;
-    if let Some(index) = gc.page_index_converter.pdf_page_index(page_index) {
+    let placeholder = gc.tags.reserve_placeholder();
+    gc.tags.push(TagNode::Placeholder(placeholder));
+
     fc.push_annotation(
-            LinkAnnotation::new(
-                rect,
-                None,
-                Target::Destination(krilla::destination::Destination::Xyz(
-                    XyzDestination::new(index, pos.point.to_krilla()),
-                )),
-            )
-            .into(),
+        placeholder,
+        Annotation::new_link(LinkAnnotation::new(rect, None, target), alt),
     );
-    }
+}
+
+fn pos_to_target(gc: &mut GlobalContext, pos: Position) -> Option<Target> {
+    let page_index = pos.page.get() - 1;
+    let index = gc.page_index_converter.pdf_page_index(page_index)?;
+
+    let dest = XyzDestination::new(index, pos.point.to_krilla());
+    Some(Target::Destination(krilla::destination::Destination::Xyz(dest)))
 }

crates/typst-pdf/src/tags.rs

@@ -0,0 +1,209 @@
+use std::cell::OnceCell;
+
+use krilla::surface::Surface;
+use krilla::tagging::{ContentTag, Identifier, Node, Tag, TagGroup, TagTree};
+use typst_library::foundations::{Content, StyleChain};
+use typst_library::introspection::Location;
+use typst_library::model::{HeadingElem, OutlineElem, OutlineEntry};
+
+use crate::convert::GlobalContext;
+
+pub(crate) struct Tags {
+    /// The intermediary stack of nested tag groups.
+    pub(crate) stack: Vec<(Location, Tag, Vec<TagNode>)>,
+    pub(crate) placeholders: Vec<OnceCell<Node>>,
+    pub(crate) in_artifact: bool,
+
+    /// The output.
+    pub(crate) tree: Vec<TagNode>,
+}
+
+pub(crate) enum TagNode {
+    Group(Tag, Vec<TagNode>),
+    Leaf(Identifier),
+    /// Allows inserting a placeholder into the tag tree.
+    /// Currently used for [`krilla::page::Page::add_tagged_annotation`].
+    Placeholder(Placeholder),
+}
+
+#[derive(Clone, Copy)]
+pub(crate) struct Placeholder(usize);
+
+impl Tags {
+    pub(crate) fn new() -> Self {
+        Self {
+            stack: Vec::new(),
+            placeholders: Vec::new(),
+            in_artifact: false,
+
+            tree: Vec::new(),
+        }
+    }
+
+    pub(crate) fn reserve_placeholder(&mut self) -> Placeholder {
+        let idx = self.placeholders.len();
+        self.placeholders.push(OnceCell::new());
+        Placeholder(idx)
+    }
+
+    pub(crate) fn init_placeholder(&mut self, placeholder: Placeholder, node: Node) {
+        self.placeholders[placeholder.0]
+            .set(node)
+            .map_err(|_| ())
+            .expect("placeholder to be uninitialized");
+    }
+
+    pub(crate) fn take_placeholder(&mut self, placeholder: Placeholder) -> Node {
+        self.placeholders[placeholder.0]
+            .take()
+            .expect("initialized placeholder node")
+    }
+
+    pub(crate) fn push(&mut self, node: TagNode) {
+        if let Some((_, _, nodes)) = self.stack.last_mut() {
+            nodes.push(node);
+        } else {
+            self.tree.push(node);
+        }
+    }
+
+    pub(crate) fn build_tree(&mut self) -> TagTree {
+        let mut tree = TagTree::new();
+        let nodes = std::mem::take(&mut self.tree);
+        // PERF: collect into vec and construct TagTree directly from tag nodes.
+        for node in nodes.into_iter().map(|node| self.resolve_node(node)) {
+            tree.push(node);
+        }
+        tree
+    }
+
+    /// Resolves [`Placeholder`] nodes.
+    fn resolve_node(&mut self, node: TagNode) -> Node {
+        match node {
+            TagNode::Group(tag, nodes) => {
+                let mut group = TagGroup::new(tag);
+                // PERF: collect into vec and construct TagTree directly from tag nodes.
+                for node in nodes.into_iter().map(|node| self.resolve_node(node)) {
+                    group.push(node);
+                }
+                Node::Group(group)
+            }
+            TagNode::Leaf(identifier) => Node::Leaf(identifier),
+            TagNode::Placeholder(placeholder) => self.take_placeholder(placeholder),
+        }
+    }
+
+    pub(crate) fn context_supports(&self, tag: &Tag) -> bool {
+        let Some((_, parent, _)) = self.stack.last() else { return true };
+
+        use Tag::*;
+
+        match parent {
+            Part => true,
+            Article => !matches!(tag, Article),
+            Section => true,
+            BlockQuote => todo!(),
+            Caption => todo!(),
+            TOC => matches!(tag, TOC | TOCI),
+            // TODO: NonStruct is allowed to but (currently?) not supported by krilla
+            TOCI => matches!(tag, TOC | Lbl | Reference | P),
+            Index => todo!(),
+            P => todo!(),
+            H1(_) => todo!(),
+            H2(_) => todo!(),
+            H3(_) => todo!(),
+            H4(_) => todo!(),
+            H5(_) => todo!(),
+            H6(_) => todo!(),
+            L(_list_numbering) => todo!(),
+            LI => todo!(),
+            Lbl => todo!(),
+            LBody => todo!(),
+            Table => todo!(),
+            TR => todo!(),
+            TH(_table_header_scope) => todo!(),
+            TD => todo!(),
+            THead => todo!(),
+            TBody => todo!(),
+            TFoot => todo!(),
+            InlineQuote => todo!(),
+            Note => todo!(),
+            Reference => todo!(),
+            BibEntry => todo!(),
+            Code => todo!(),
+            Link => todo!(),
+            Annot => todo!(),
+            Figure(_) => todo!(),
+            Formula(_) => todo!(),
+            Datetime => todo!(),
+            Terms => todo!(),
+            Title => todo!(),
+        }
+    }
+}
+
+pub(crate) fn handle_open_tag(
+    gc: &mut GlobalContext,
+    surface: &mut Surface,
+    elem: &Content,
+) {
+    if gc.tags.in_artifact {
+        return;
+    }
+
+    let Some(loc) = elem.location() else { return };
+
+    let tag = if let Some(heading) = elem.to_packed::<HeadingElem>() {
+        let level = heading.resolve_level(StyleChain::default());
+        let name = heading.body.plain_text().to_string();
+        match level.get() {
+            1 => Tag::H1(Some(name)),
+            2 => Tag::H2(Some(name)),
+            3 => Tag::H3(Some(name)),
+            4 => Tag::H4(Some(name)),
+            5 => Tag::H5(Some(name)),
+            // TODO: when targeting PDF 2.0 headings `> 6` are supported
+            _ => Tag::H6(Some(name)),
+        }
+    } else if let Some(_) = elem.to_packed::<OutlineElem>() {
+        Tag::TOC
+    } else if let Some(_outline_entry) = elem.to_packed::<OutlineEntry>() {
+        Tag::TOCI
+    } else {
+        return;
+    };
+
+    if !gc.tags.context_supports(&tag) {
+        // TODO: error or warning?
+    }
+
+    // close previous marked-content and open a nested tag.
+    if !gc.tags.stack.is_empty() {
+        surface.end_tagged();
+    }
+    let content_id = surface.start_tagged(krilla::tagging::ContentTag::Other);
+
+    gc.tags.stack.push((loc, tag, vec![TagNode::Leaf(content_id)]));
+}
+
+pub(crate) fn handle_close_tag(
+    gc: &mut GlobalContext,
+    surface: &mut Surface,
+    loc: &Location,
+) {
+    let Some((_, tag, nodes)) = gc.tags.stack.pop_if(|(l, ..)| l == loc) else {
+        return;
+    };
+
+    surface.end_tagged();
+
+    if let Some((_, _, parent_nodes)) = gc.tags.stack.last_mut() {
+        parent_nodes.push(TagNode::Group(tag, nodes));
+
+        // TODO: somehow avoid empty marked-content sequences
+        let id = surface.start_tagged(ContentTag::Other);
+        parent_nodes.push(TagNode::Leaf(id));
+    } else {
+        gc.tags.tree.push(TagNode::Group(tag, nodes));
+    }
+}

crates/typst-render/src/lib.rs

@@ -167,7 +167,7 @@ fn render_frame(canvas: &mut sk::Pixmap, state: State, frame: &Frame) {
             FrameItem::Image(image, size, _) => {
                 image::render_image(canvas, state.pre_translate(*pos), image, *size);
             }
-            FrameItem::Link(_, _) => {}
+            FrameItem::Link(..) => {}
             FrameItem::Tag(_) => {}
         }
     }

crates/typst-svg/src/lib.rs

@@ -207,7 +207,7 @@ impl SVGRenderer {
         for (pos, item) in frame.items() {
             // File size optimization.
             // TODO: SVGs could contain links, couldn't they?
-            if matches!(item, FrameItem::Link(_, _) | FrameItem::Tag(_)) {
+            if matches!(item, FrameItem::Link(..) | FrameItem::Tag(_)) {
                 continue;
             }
 
@@ -228,7 +228,7 @@ impl SVGRenderer {
                     self.render_shape(state.pre_translate(*pos), shape)
                 }
                 FrameItem::Image(image, size, _) => self.render_image(image, size),
-                FrameItem::Link(_, _) => unreachable!(),
+                FrameItem::Link(..) => unreachable!(),
                 FrameItem::Tag(_) => unreachable!(),
             };
 

tests/src/run.rs

@@ -505,7 +505,7 @@ fn render_links(canvas: &mut sk::Pixmap, ts: sk::Transform, frame: &Frame) {
                 let ts = ts.pre_concat(to_sk_transform(&group.transform));
                 render_links(canvas, ts, &group.frame);
             }
-            FrameItem::Link(_, size) => {
+            FrameItem::Link(_, _, size) => {
                 let w = size.x.to_pt() as f32;
                 let h = size.y.to_pt() as f32;
                 let rect = sk::Rect::from_xywh(0.0, 0.0, w, h).unwrap();

tests/suite/math/equation.typ

@@ -297,3 +297,10 @@ Looks at the @quadratic formula.
 #set page(width: 150pt)
 #set text(lang: "he")
 תהא סדרה $a_n$: $[a_n: 1, 1/2, 1/3, dots]$
+
+--- issue-6170-equation-stroke ---
+// In this bug stroke settings did not apply to math content.
+// We expect all of these to have a green stroke.
+#set text(stroke: green + 0.5pt)
+
+A $B^2$ $ grave(C)' $

tests/suite/math/multiline.typ

@@ -99,6 +99,9 @@ Multiple trailing line breaks.
 #let hrule(x) = box(line(length: x))
 #hrule(90pt)$<;$\
 #hrule(95pt)$<;$\
+// We don't linebreak before a closing paren, but do before an opening paren.
+#hrule(90pt)$<($\
+#hrule(95pt)$<($
 #hrule(90pt)$<)$\
 #hrule(95pt)$<)$