WIP [no ci]

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.
#
# 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
#

Cargo.lock

@@ -413,7 +413,7 @@ dependencies = [
 [[package]]
 name = "codex"
 version = "0.1.1"
-source = "git+https://github.com/typst/codex?rev=56eb217#56eb2172fc0670f4c1c8b79a63d11f9354e5babe"
+source = "git+https://github.com/typst/codex?rev=a5428cb#a5428cb9c81a41354d44b44dbd5a16a710bbd928"
 
 [[package]]
 name = "color-print"
@@ -1367,7 +1367,6 @@ dependencies = [
 [[package]]
 name = "krilla"
 version = "0.4.0"
-source = "git+https://github.com/LaurenzV/krilla?rev=20c14fe#20c14fefee5002566b3d6668b338bbe2168784e7"
 dependencies = [
  "base64",
  "bumpalo",
@@ -1395,7 +1394,6 @@ dependencies = [
 [[package]]
 name = "krilla-svg"
 version = "0.1.0"
-source = "git+https://github.com/LaurenzV/krilla?rev=20c14fe#20c14fefee5002566b3d6668b338bbe2168784e7"
 dependencies = [
  "flate2",
  "fontdb",
@@ -2911,7 +2909,7 @@ dependencies = [
 [[package]]
 name = "typst-dev-assets"
 version = "0.13.1"
-source = "git+https://github.com/typst/typst-dev-assets?rev=fddbf8b#fddbf8b99506bc370ac0edcd4959add603a7fc92"
+source = "git+https://github.com/typst/typst-dev-assets?rev=bfa947f#bfa947f3433d7d13a995168c40ae788a2ebfe648"
 
 [[package]]
 name = "typst-docs"

Cargo.toml

@@ -33,7 +33,7 @@ typst-syntax = { path = "crates/typst-syntax", version = "0.13.1" }
 typst-timing = { path = "crates/typst-timing", version = "0.13.1" }
 typst-utils = { path = "crates/typst-utils", version = "0.13.1" }
 typst-assets = { git = "https://github.com/typst/typst-assets", rev = "c1089b4" }
-typst-dev-assets = { git = "https://github.com/typst/typst-dev-assets", rev = "fddbf8b" }
+typst-dev-assets = { git = "https://github.com/typst/typst-dev-assets", rev = "bfa947f" }
 arrayvec = "0.7.4"
 az = "1.2"
 base64 = "0.22"
@@ -47,7 +47,7 @@ clap = { version = "4.4", features = ["derive", "env", "wrap_help"] }
 clap_complete = "4.2.1"
 clap_mangen = "0.2.10"
 codespan-reporting = "0.11"
-codex = { git = "https://github.com/typst/codex", rev = "56eb217" }
+codex = { git = "https://github.com/typst/codex", rev = "a5428cb" }
 color-print = "0.3.6"
 comemo = "0.4"
 csv = "1"
@@ -73,8 +73,8 @@ image = { version = "0.25.5", default-features = false, features = ["png", "jpeg
 indexmap = { version = "2", features = ["serde"] }
 infer = { version = "0.19.0", default-features = false }
 kamadak-exif = "0.6"
-krilla = { git = "https://github.com/LaurenzV/krilla", rev = "20c14fe", default-features = false, features = ["raster-images", "comemo", "rayon"] }
-krilla-svg = { git = "https://github.com/LaurenzV/krilla", rev = "20c14fe" }
+krilla = { path = "../krilla/crates/krilla", default-features = false, features = ["raster-images", "comemo", "rayon"] }
+krilla-svg = { path = "../krilla/crates/krilla-svg" }
 kurbo = "0.11"
 libfuzzer-sys = "0.4"
 lipsum = "0.9"

crates/typst-cli/src/args.rs

@@ -246,6 +246,13 @@ pub struct CompileArgs {
     #[arg(long = "pdf-standard", value_delimiter = ',')]
     pub pdf_standard: Vec<PdfStandard>,
 
+    /// By default, even when not producing a `PDF/UA-1` document, a tagged PDF
+    /// document is written to provide a baseline of accessibility. In some
+    /// circumstances (for example when trying to reduce the size of a document)
+    /// it can be desirable to disable tagged PDF.
+    #[arg(long = "disable-pdf-tags")]
+    pub disable_pdf_tags: bool,
+
     /// The PPI (pixels per inch) to use for PNG export.
     #[arg(long = "ppi", default_value_t = 144.0)]
     pub ppi: f32,
@@ -506,6 +513,9 @@ pub enum PdfStandard {
     /// PDF/A-4e.
     #[value(name = "a-4e")]
     A_4e,
+    /// PDF/UA-1.
+    #[value(name = "ua-1")]
+    Ua_1,
 }
 
 display_possible_values!(PdfStandard);

crates/typst-cli/src/compile.rs

@@ -65,6 +65,8 @@ pub struct CompileConfig {
     pub open: Option<Option<String>>,
     /// A list of standards the PDF should conform to.
     pub pdf_standards: PdfStandards,
+    /// Whether to write PDF (accessibility) tags.
+    pub disable_pdf_tags: bool,
     /// A path to write a Makefile rule describing the current compilation.
     pub make_deps: Option<PathBuf>,
     /// The PPI (pixels per inch) to use for PNG export.
@@ -150,6 +152,7 @@ impl CompileConfig {
             output_format,
             pages,
             pdf_standards,
+            disable_pdf_tags: args.disable_pdf_tags,
             creation_timestamp: args.world.creation_timestamp,
             make_deps: args.make_deps.clone(),
             ppi: args.ppi,
@@ -291,6 +294,7 @@ fn export_pdf(document: &PagedDocument, config: &CompileConfig) -> SourceResult<
         timestamp,
         page_ranges: config.pages.clone(),
         standards: config.pdf_standards.clone(),
+        disable_tags: config.disable_pdf_tags,
     };
     let buffer = typst_pdf::pdf(document, &options)?;
     config
@@ -773,6 +777,7 @@ impl From<PdfStandard> for typst_pdf::PdfStandard {
             PdfStandard::A_4 => typst_pdf::PdfStandard::A_4,
             PdfStandard::A_4f => typst_pdf::PdfStandard::A_4f,
             PdfStandard::A_4e => typst_pdf::PdfStandard::A_4e,
+            PdfStandard::Ua_1 => typst_pdf::PdfStandard::Ua_1,
         }
     }
 }

crates/typst-eval/src/markup.rs

@@ -205,7 +205,9 @@ impl Eval for ast::Label<'_> {
     type Output = Value;
 
     fn eval(self, _: &mut Vm) -> SourceResult<Self::Output> {
-        Ok(Value::Label(Label::new(PicoStr::intern(self.get()))))
+        Ok(Value::Label(
+            Label::new(PicoStr::intern(self.get())).expect("unexpected empty label"),
+        ))
     }
 }
 
@@ -213,7 +215,8 @@ impl Eval for ast::Ref<'_> {
     type Output = Content;
 
     fn eval(self, vm: &mut Vm) -> SourceResult<Self::Output> {
-        let target = Label::new(PicoStr::intern(self.target()));
+        let target = Label::new(PicoStr::intern(self.target()))
+            .expect("unexpected empty reference");
         let mut elem = RefElem::new(target);
         if let Some(supplement) = self.supplement() {
             elem.push_supplement(Smart::Custom(Some(Supplement::Content(

crates/typst-html/src/encode.rs

@@ -3,9 +3,8 @@ use std::fmt::Write;
 use typst_library::diag::{bail, At, SourceResult, StrResult};
 use typst_library::foundations::Repr;
 use typst_library::html::{
-    attr, charsets, tag, HtmlDocument, HtmlElement, HtmlNode, HtmlTag,
+    attr, charsets, tag, HtmlDocument, HtmlElement, HtmlFrame, HtmlNode, HtmlTag,
 };
-use typst_library::layout::Frame;
 use typst_syntax::Span;
 
 /// Encodes an HTML document into a string.
@@ -304,9 +303,15 @@ fn write_escape(w: &mut Writer, c: char) -> StrResult<()> {
 }
 
 /// Encode a laid out frame into the writer.
-fn write_frame(w: &mut Writer, frame: &Frame) {
+fn write_frame(w: &mut Writer, frame: &HtmlFrame) {
     // FIXME: This string replacement is obviously a hack.
-    let svg = typst_svg::svg_frame(frame)
-        .replace("<svg class", "<svg style=\"overflow: visible;\" class");
+    let svg = typst_svg::svg_frame(&frame.inner).replace(
+        "<svg class",
+        &format!(
+            "<svg style=\"overflow: visible; width: {}em; height: {}em;\" class",
+            frame.inner.width() / frame.text_size,
+            frame.inner.height() / frame.text_size,
+        ),
+    );
     w.buf.push_str(&svg);
 }

crates/typst-html/src/lib.rs

@@ -9,7 +9,7 @@ use typst_library::diag::{bail, warning, At, SourceResult};
 use typst_library::engine::{Engine, Route, Sink, Traced};
 use typst_library::foundations::{Content, StyleChain, Target, TargetElem};
 use typst_library::html::{
-    attr, tag, FrameElem, HtmlDocument, HtmlElem, HtmlElement, HtmlNode,
+    attr, tag, FrameElem, HtmlDocument, HtmlElem, HtmlElement, HtmlFrame, HtmlNode,
 };
 use typst_library::introspection::{
     Introspector, Locator, LocatorLink, SplitLocator, TagElem,
@@ -246,7 +246,10 @@ fn handle(
             styles.chain(&style),
             Region::new(Size::splat(Abs::inf()), Axes::splat(false)),
         )?;
-        output.push(HtmlNode::Frame(frame));
+        output.push(HtmlNode::Frame(HtmlFrame {
+            inner: frame,
+            text_size: TextElem::size_in(styles),
+        }));
     } else {
         engine.sink.warn(warning!(
             child.span(),

crates/typst-ide/src/complete.rs

@@ -448,7 +448,7 @@ fn field_access_completions(
     match value {
         Value::Symbol(symbol) => {
             for modifier in symbol.modifiers() {
-                if let Ok(modified) = symbol.clone().modified(modifier) {
+                if let Ok(modified) = symbol.clone().modified((), modifier) {
                     ctx.completions.push(Completion {
                         kind: CompletionKind::Symbol(modified.get()),
                         label: modifier.into(),

crates/typst-ide/src/definition.rs

@@ -72,7 +72,8 @@ pub fn definition(
 
         // Try to jump to the referenced content.
         DerefTarget::Ref(node) => {
-            let label = Label::new(PicoStr::intern(node.cast::<ast::Ref>()?.target()));
+            let label = Label::new(PicoStr::intern(node.cast::<ast::Ref>()?.target()))
+                .expect("unexpected empty reference");
             let selector = Selector::Label(label);
             let elem = document?.introspector.query_first(&selector)?;
             return Some(Definition::Span(elem.span()));

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/inline/line.rs

@@ -219,7 +219,7 @@ fn collect_items<'a>(
     // Add fallback text to expand the line height, if necessary.
     if !items.iter().any(|item| matches!(item, Item::Text(_))) {
         if let Some(fallback) = fallback {
-            items.push(fallback);
+            items.push(fallback, usize::MAX);
         }
     }
 
@@ -270,10 +270,10 @@ fn collect_range<'a>(
     items: &mut Items<'a>,
     fallback: &mut Option<ItemEntry<'a>>,
 ) {
-    for (subrange, item) in p.slice(range.clone()) {
+    for (idx, (subrange, item)) in p.slice(range.clone()).enumerate() {
         // All non-text items are just kept, they can't be split.
         let Item::Text(shaped) = item else {
-            items.push(item);
+            items.push(item, idx);
             continue;
         };
 
@@ -293,10 +293,10 @@ fn collect_range<'a>(
         } else if split {
             // When the item is split in half, reshape it.
             let reshaped = shaped.reshape(engine, sliced);
-            items.push(Item::Text(reshaped));
+            items.push(Item::Text(reshaped), idx);
         } else {
             // When the item is fully contained, just keep it.
-            items.push(item);
+            items.push(item, idx);
         }
     }
 }
@@ -499,16 +499,16 @@ pub fn commit(
 
     // Build the frames and determine the height and baseline.
     let mut frames = vec![];
-    for item in line.items.iter() {
-        let mut push = |offset: &mut Abs, frame: Frame| {
+    for &(idx, ref item) in line.items.indexed_iter() {
+        let mut push = |offset: &mut Abs, frame: Frame, idx: usize| {
             let width = frame.width();
             top.set_max(frame.baseline());
             bottom.set_max(frame.size().y - frame.baseline());
-            frames.push((*offset, frame));
+            frames.push((*offset, frame, idx));
             *offset += width;
         };
 
-        match item {
+        match &**item {
             Item::Absolute(v, _) => {
                 offset += *v;
             }
@@ -520,7 +520,7 @@ pub fn commit(
                         layout_box(elem, engine, loc.relayout(), styles, region)
                     })?;
                     apply_baseline_shift(&mut frame, *styles);
-                    push(&mut offset, frame);
+                    push(&mut offset, frame, idx);
                 } else {
                     offset += amount;
                 }
@@ -532,15 +532,15 @@ pub fn commit(
                     justification_ratio,
                     extra_justification,
                 );
-                push(&mut offset, frame);
+                push(&mut offset, frame, idx);
             }
             Item::Frame(frame) => {
-                push(&mut offset, frame.clone());
+                push(&mut offset, frame.clone(), idx);
             }
             Item::Tag(tag) => {
                 let mut frame = Frame::soft(Size::zero());
                 frame.push(Point::zero(), FrameItem::Tag((*tag).clone()));
-                frames.push((offset, frame));
+                frames.push((offset, frame, idx));
             }
             Item::Skip(_) => {}
         }
@@ -559,8 +559,13 @@ pub fn commit(
         add_par_line_marker(&mut output, marker, engine, locator, top);
     }
 
+    // Ensure that the final frame's items are in logical order rather than in
+    // visual order. This is important because it affects the order of elements
+    // during introspection and thus things like counters.
+    frames.sort_unstable_by_key(|(_, _, idx)| *idx);
+
     // Construct the line's frame.
-    for (offset, frame) in frames {
+    for (offset, frame, _) in frames {
         let x = offset + p.config.align.position(remaining);
         let y = top - frame.baseline();
         output.push_frame(Point::new(x, y), frame);
@@ -627,7 +632,7 @@ fn overhang(c: char) -> f64 {
 }
 
 /// A collection of owned or borrowed inline items.
-pub struct Items<'a>(Vec<ItemEntry<'a>>);
+pub struct Items<'a>(Vec<(usize, ItemEntry<'a>)>);
 
 impl<'a> Items<'a> {
     /// Create empty items.
@@ -636,33 +641,38 @@ impl<'a> Items<'a> {
     }
 
     /// Push a new item.
-    pub fn push(&mut self, entry: impl Into<ItemEntry<'a>>) {
-        self.0.push(entry.into());
+    pub fn push(&mut self, entry: impl Into<ItemEntry<'a>>, idx: usize) {
+        self.0.push((idx, entry.into()));
     }
 
-    /// Iterate over the items
+    /// Iterate over the items.
     pub fn iter(&self) -> impl Iterator<Item = &Item<'a>> {
-        self.0.iter().map(|item| &**item)
+        self.0.iter().map(|(_, item)| &**item)
+    }
+
+    /// Iterate over the items with indices
+    pub fn indexed_iter(&self) -> impl Iterator<Item = &(usize, ItemEntry<'a>)> {
+        self.0.iter()
     }
 
     /// Access the first item.
     pub fn first(&self) -> Option<&Item<'a>> {
-        self.0.first().map(|item| &**item)
+        self.0.first().map(|(_, item)| &**item)
     }
 
     /// Access the last item.
     pub fn last(&self) -> Option<&Item<'a>> {
-        self.0.last().map(|item| &**item)
+        self.0.last().map(|(_, item)| &**item)
     }
 
     /// Access the first item mutably, if it is text.
     pub fn first_text_mut(&mut self) -> Option<&mut ShapedText<'a>> {
-        self.0.first_mut()?.text_mut()
+        self.0.first_mut()?.1.text_mut()
     }
 
     /// Access the last item mutably, if it is text.
     pub fn last_text_mut(&mut self) -> Option<&mut ShapedText<'a>> {
-        self.0.last_mut()?.text_mut()
+        self.0.last_mut()?.1.text_mut()
     }
 
     /// Reorder the items starting at the given index to RTL.
@@ -673,12 +683,12 @@ impl<'a> Items<'a> {
 
 impl<'a> FromIterator<ItemEntry<'a>> for Items<'a> {
     fn from_iter<I: IntoIterator<Item = ItemEntry<'a>>>(iter: I) -> Self {
-        Self(iter.into_iter().collect())
+        Self(iter.into_iter().enumerate().collect())
     }
 }
 
 impl<'a> Deref for Items<'a> {
-    type Target = Vec<ItemEntry<'a>>;
+    type Target = Vec<(usize, ItemEntry<'a>)>;
 
     fn deref(&self) -> &Self::Target {
         &self.0
@@ -698,6 +708,10 @@ impl Debug for Items<'_> {
 }
 
 /// A reference to or a boxed item.
+///
+/// This is conceptually similar to a [`Cow<'a, Item<'a>>`][std::borrow::Cow],
+/// but we box owned items since an [`Item`] is much bigger than
+/// a box.
 pub enum ItemEntry<'a> {
     Ref(&'a Item<'a>),
     Box(Box<Item<'a>>),

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

@@ -13,6 +13,7 @@ use typst_library::layout::{
     VAlignment,
 };
 use typst_library::model::Numbering;
+use typst_library::pdf::ArtifactKind;
 use typst_library::routines::{Pair, Routines};
 use typst_library::text::{LocalName, TextElem};
 use typst_library::visualize::Paint;
@@ -200,6 +201,11 @@ fn layout_page_run_impl(
 
     // Layout marginals.
     let mut layouted = Vec::with_capacity(fragment.len());
+
+    let header = header.as_ref().map(|h| h.clone().artifact(ArtifactKind::Header));
+    let footer = footer.as_ref().map(|f| f.clone().artifact(ArtifactKind::Footer));
+    let background = background.as_ref().map(|b| b.clone().artifact(ArtifactKind::Page));
+
     for inner in fragment {
         let header_size = Size::new(inner.width(), margin.top - header_ascent);
         let footer_size = Size::new(inner.width(), margin.bottom - footer_descent);
@@ -210,9 +216,9 @@ fn layout_page_run_impl(
             fill: fill.clone(),
             numbering: numbering.clone(),
             supplement: supplement.clone(),
-            header: layout_marginal(header, header_size, Alignment::BOTTOM)?,
-            footer: layout_marginal(footer, footer_size, Alignment::TOP)?,
-            background: layout_marginal(background, full_size, mid)?,
+            header: layout_marginal(&header, header_size, Alignment::BOTTOM)?,
+            footer: layout_marginal(&footer, footer_size, Alignment::TOP)?,
+            background: layout_marginal(&background, full_size, mid)?,
             foreground: layout_marginal(foreground, full_size, mid)?,
             margin,
             binding,

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

@@ -16,12 +16,13 @@ use crate::diag::{SourceResult, StrResult};
 use crate::engine::Engine;
 use crate::foundations::{
     elem, func, scope, ty, Context, Dict, Element, Fields, IntoValue, Label,
-    NativeElement, Recipe, RecipeIndex, Repr, Selector, Str, Style, StyleChain, Styles,
-    Value,
+    NativeElement, Recipe, RecipeIndex, Repr, Selector, Show, Str, Style, StyleChain,
+    Styles, Value,
 };
-use crate::introspection::Location;
+use crate::introspection::{Locatable, Location};
 use crate::layout::{AlignElem, Alignment, Axes, Length, MoveElem, PadElem, Rel, Sides};
 use crate::model::{Destination, EmphElem, LinkElem, StrongElem};
+use crate::pdf::{ArtifactElem, ArtifactKind};
 use crate::text::UnderlineElem;
 
 /// A piece of document content.
@@ -503,8 +504,12 @@ impl Content {
     }
 
     /// Link the content somewhere.
-    pub fn linked(self, dest: Destination) -> Self {
-        self.styled(LinkElem::set_current(Some(dest)))
+    pub fn linked(self, dest: Destination, alt: Option<EcoString>) -> Self {
+        let span = self.span();
+        LinkMarker::new(self, dest.clone(), alt)
+            .pack()
+            .spanned(span)
+            .styled(LinkElem::set_current(Some(dest)))
     }
 
     /// Set alignments for this content.
@@ -533,6 +538,12 @@ impl Content {
             .pack()
             .spanned(span)
     }
+
+    /// Link the content somewhere.
+    pub fn artifact(self, kind: ArtifactKind) -> Self {
+        let span = self.span();
+        ArtifactElem::new(self).with_kind(kind).pack().spanned(span)
+    }
 }
 
 #[scope]
@@ -980,6 +991,24 @@ pub trait PlainText {
     fn plain_text(&self, text: &mut EcoString);
 }
 
+/// An element that associates the body of a link with the destination.
+#[elem(Show, Locatable)]
+pub struct LinkMarker {
+    /// The content.
+    #[required]
+    pub body: Content,
+    #[required]
+    pub dest: Destination,
+    #[required]
+    pub alt: Option<EcoString>,
+}
+
+impl Show for Packed<LinkMarker> {
+    fn show(&self, _: &mut Engine, _: StyleChain) -> SourceResult<Content> {
+        Ok(self.body.clone())
+    }
+}
+
 /// An error arising when trying to access a field of content.
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
 pub enum FieldAccessError {

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

@@ -1,7 +1,8 @@
 use ecow::{eco_format, EcoString};
 use typst_utils::{PicoStr, ResolvedPicoStr};
 
-use crate::foundations::{func, scope, ty, Repr, Str};
+use crate::diag::StrResult;
+use crate::foundations::{bail, func, scope, ty, Repr, Str};
 
 /// A label for an element.
 ///
@@ -27,7 +28,8 @@ use crate::foundations::{func, scope, ty, Repr, Str};
 /// # Syntax
 /// This function also has dedicated syntax: You can create a label by enclosing
 /// its name in angle brackets. This works both in markup and code. A label's
-/// name can contain letters, numbers, `_`, `-`, `:`, and `.`.
+/// name can contain letters, numbers, `_`, `-`, `:`, and `.`. A label cannot
+/// be empty.
 ///
 /// Note that there is a syntactical difference when using the dedicated syntax
 /// for this function. In the code below, the `[<a>]` terminates the heading and
@@ -50,8 +52,11 @@ pub struct Label(PicoStr);
 
 impl Label {
     /// Creates a label from an interned string.
-    pub fn new(name: PicoStr) -> Self {
-        Self(name)
+    ///
+    /// Returns `None` if the given string is empty.
+    pub fn new(name: PicoStr) -> Option<Self> {
+        const EMPTY: PicoStr = PicoStr::constant("");
+        (name != EMPTY).then_some(Self(name))
     }
 
     /// Resolves the label to a string.
@@ -70,10 +75,14 @@ impl Label {
     /// Creates a label from a string.
     #[func(constructor)]
     pub fn construct(
-        /// The name of the label.
+        /// The name of the label. Must not be empty.
         name: Str,
-    ) -> Label {
-        Self(PicoStr::intern(name.as_str()))
+    ) -> StrResult<Label> {
+        if name.is_empty() {
+            bail!("label name must not be empty");
+        }
+
+        Ok(Self(PicoStr::intern(name.as_str())))
     }
 }
 

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

@@ -19,11 +19,8 @@ use crate::foundations::{repr, ty, Content, Scope, Value};
 ///
 /// You can access definitions from the module using [field access
 /// notation]($scripting/#fields) and interact with it using the [import and
-/// include syntaxes]($scripting/#modules). Alternatively, it is possible to
-/// convert a module to a dictionary, and therefore access its contents
-/// dynamically, using the [dictionary constructor]($dictionary/#constructor).
+/// include syntaxes]($scripting/#modules).
 ///
-/// # Example
 /// ```example
 /// <<< #import "utils.typ"
 /// <<< #utils.add(2, 5)
@@ -34,6 +31,20 @@ use crate::foundations::{repr, ty, Content, Scope, Value};
 /// >>>
 /// >>> #(-3)
 /// ```
+///
+/// You can check whether a definition is present in a module using the `{in}`
+/// operator, with a string on the left-hand side. This can be useful to
+/// [conditionally access]($category/foundations/std/#conditional-access)
+/// definitions in a module.
+///
+/// ```example
+/// #("table" in std) \
+/// #("nope" in std)
+/// ```
+///
+/// Alternatively, it is possible to convert a module to a dictionary, and
+/// therefore access its contents dynamically, using the [dictionary
+/// constructor]($dictionary/#constructor).
 #[ty(cast)]
 #[derive(Clone, Hash)]
 #[allow(clippy::derived_hash_with_manual_eq)]

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

@@ -558,6 +558,7 @@ pub fn contains(lhs: &Value, rhs: &Value) -> Option<bool> {
         (Str(a), Str(b)) => Some(b.as_str().contains(a.as_str())),
         (Dyn(a), Str(b)) => a.downcast::<Regex>().map(|regex| regex.is_match(b)),
         (Str(a), Dict(b)) => Some(b.contains(a)),
+        (Str(a), Module(b)) => Some(b.scope().get(a).is_some()),
         (a, Array(b)) => Some(b.contains(a.clone())),
 
         _ => Option::None,

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

@@ -8,7 +8,7 @@ use serde::{Serialize, Serializer};
 use typst_syntax::{is_ident, Span, Spanned};
 use typst_utils::hash128;
 
-use crate::diag::{bail, SourceResult, StrResult};
+use crate::diag::{bail, DeprecationSink, SourceResult, StrResult};
 use crate::foundations::{
     cast, elem, func, scope, ty, Array, Content, Func, NativeElement, NativeFunc, Packed,
     PlainText, Repr as _,
@@ -54,18 +54,22 @@ enum Repr {
     /// A native symbol that has no named variant.
     Single(char),
     /// A native symbol with multiple named variants.
-    Complex(&'static [(ModifierSet<&'static str>, char)]),
+    Complex(&'static [Variant<&'static str>]),
     /// A symbol with multiple named variants, where some modifiers may have
     /// been applied. Also used for symbols defined at runtime by the user with
     /// no modifier applied.
     Modified(Arc<(List, ModifierSet<EcoString>)>),
 }
 
+/// A symbol variant, consisting of a set of modifiers, a character, and an
+/// optional deprecation message.
+type Variant<S> = (ModifierSet<S>, char, Option<S>);
+
 /// A collection of symbols.
 #[derive(Clone, Eq, PartialEq, Hash)]
 enum List {
-    Static(&'static [(ModifierSet<&'static str>, char)]),
-    Runtime(Box<[(ModifierSet<EcoString>, char)]>),
+    Static(&'static [Variant<&'static str>]),
+    Runtime(Box<[Variant<EcoString>]>),
 }
 
 impl Symbol {
@@ -76,14 +80,14 @@ impl Symbol {
 
     /// Create a symbol with a static variant list.
     #[track_caller]
-    pub const fn list(list: &'static [(ModifierSet<&'static str>, char)]) -> Self {
+    pub const fn list(list: &'static [Variant<&'static str>]) -> Self {
         debug_assert!(!list.is_empty());
         Self(Repr::Complex(list))
     }
 
     /// Create a symbol with a runtime variant list.
     #[track_caller]
-    pub fn runtime(list: Box<[(ModifierSet<EcoString>, char)]>) -> Self {
+    pub fn runtime(list: Box<[Variant<EcoString>]>) -> Self {
         debug_assert!(!list.is_empty());
         Self(Repr::Modified(Arc::new((List::Runtime(list), ModifierSet::default()))))
     }
@@ -93,9 +97,11 @@ impl Symbol {
         match &self.0 {
             Repr::Single(c) => *c,
             Repr::Complex(_) => ModifierSet::<&'static str>::default()
-                .best_match_in(self.variants())
+                .best_match_in(self.variants().map(|(m, c, _)| (m, c)))
                 .unwrap(),
-            Repr::Modified(arc) => arc.1.best_match_in(self.variants()).unwrap(),
+            Repr::Modified(arc) => {
+                arc.1.best_match_in(self.variants().map(|(m, c, _)| (m, c))).unwrap()
+            }
         }
     }
 
@@ -128,7 +134,11 @@ impl Symbol {
     }
 
     /// Apply a modifier to the symbol.
-    pub fn modified(mut self, modifier: &str) -> StrResult<Self> {
+    pub fn modified(
+        mut self,
+        sink: impl DeprecationSink,
+        modifier: &str,
+    ) -> StrResult<Self> {
         if let Repr::Complex(list) = self.0 {
             self.0 =
                 Repr::Modified(Arc::new((List::Static(list), ModifierSet::default())));
@@ -137,7 +147,12 @@ impl Symbol {
         if let Repr::Modified(arc) = &mut self.0 {
             let (list, modifiers) = Arc::make_mut(arc);
             modifiers.insert_raw(modifier);
-            if modifiers.best_match_in(list.variants()).is_some() {
+            if let Some(deprecation) =
+                modifiers.best_match_in(list.variants().map(|(m, _, d)| (m, d)))
+            {
+                if let Some(message) = deprecation {
+                    sink.emit(message)
+                }
                 return Ok(self);
             }
         }
@@ -146,7 +161,7 @@ impl Symbol {
     }
 
     /// The characters that are covered by this symbol.
-    pub fn variants(&self) -> impl Iterator<Item = (ModifierSet<&str>, char)> {
+    pub fn variants(&self) -> impl Iterator<Item = Variant<&str>> {
         match &self.0 {
             Repr::Single(c) => Variants::Single(Some(*c).into_iter()),
             Repr::Complex(list) => Variants::Static(list.iter()),
@@ -161,7 +176,7 @@ impl Symbol {
             _ => ModifierSet::default(),
         };
         self.variants()
-            .flat_map(|(m, _)| m)
+            .flat_map(|(m, _, _)| m)
             .filter(|modifier| !modifier.is_empty() && !modifiers.contains(modifier))
             .collect::<BTreeSet<_>>()
             .into_iter()
@@ -256,7 +271,7 @@ impl Symbol {
 
         let list = variants
             .into_iter()
-            .map(|s| (ModifierSet::from_raw_dotted(s.v.0), s.v.1))
+            .map(|s| (ModifierSet::from_raw_dotted(s.v.0), s.v.1, None))
             .collect();
         Ok(Symbol::runtime(list))
     }
@@ -316,17 +331,17 @@ impl crate::foundations::Repr for Symbol {
 }
 
 fn repr_variants<'a>(
-    variants: impl Iterator<Item = (ModifierSet<&'a str>, char)>,
+    variants: impl Iterator<Item = Variant<&'a str>>,
     applied_modifiers: ModifierSet<&str>,
 ) -> String {
     crate::foundations::repr::pretty_array_like(
         &variants
-            .filter(|(modifiers, _)| {
+            .filter(|(modifiers, _, _)| {
                 // Only keep variants that can still be accessed, i.e., variants
                 // that contain all applied modifiers.
                 applied_modifiers.iter().all(|am| modifiers.contains(am))
             })
-            .map(|(modifiers, c)| {
+            .map(|(modifiers, c, _)| {
                 let trimmed_modifiers =
                     modifiers.into_iter().filter(|&m| !applied_modifiers.contains(m));
                 if trimmed_modifiers.clone().all(|m| m.is_empty()) {
@@ -379,18 +394,20 @@ cast! {
 /// Iterator over variants.
 enum Variants<'a> {
     Single(std::option::IntoIter<char>),
-    Static(std::slice::Iter<'static, (ModifierSet<&'static str>, char)>),
-    Runtime(std::slice::Iter<'a, (ModifierSet<EcoString>, char)>),
+    Static(std::slice::Iter<'static, Variant<&'static str>>),
+    Runtime(std::slice::Iter<'a, Variant<EcoString>>),
 }
 
 impl<'a> Iterator for Variants<'a> {
-    type Item = (ModifierSet<&'a str>, char);
+    type Item = Variant<&'a str>;
 
     fn next(&mut self) -> Option<Self::Item> {
         match self {
-            Self::Single(iter) => Some((ModifierSet::default(), iter.next()?)),
+            Self::Single(iter) => Some((ModifierSet::default(), iter.next()?, None)),
             Self::Static(list) => list.next().copied(),
-            Self::Runtime(list) => list.next().map(|(m, c)| (m.as_deref(), *c)),
+            Self::Runtime(list) => {
+                list.next().map(|(m, c, d)| (m.as_deref(), *c, d.as_deref()))
+            }
         }
     }
 }

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

@@ -157,7 +157,9 @@ impl Value {
     /// Try to access a field on the value.
     pub fn field(&self, field: &str, sink: impl DeprecationSink) -> StrResult<Value> {
         match self {
-            Self::Symbol(symbol) => symbol.clone().modified(field).map(Self::Symbol),
+            Self::Symbol(symbol) => {
+                symbol.clone().modified(sink, field).map(Self::Symbol)
+            }
             Self::Version(version) => version.component(field).map(Self::Int),
             Self::Dict(dict) => dict.get(field).cloned(),
             Self::Content(content) => content.field_by_name(field),

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

@@ -7,7 +7,7 @@ use typst_utils::{PicoStr, ResolvedPicoStr};
 use crate::diag::{bail, HintedStrResult, StrResult};
 use crate::foundations::{cast, Dict, Repr, Str};
 use crate::introspection::{Introspector, Tag};
-use crate::layout::Frame;
+use crate::layout::{Abs, Frame};
 use crate::model::DocumentInfo;
 
 /// An HTML document.
@@ -30,8 +30,8 @@ pub enum HtmlNode {
     Text(EcoString, Span),
     /// Another element.
     Element(HtmlElement),
-    /// A frame that will be displayed as an embedded SVG.
-    Frame(Frame),
+    /// Layouted content that will be embedded into HTML as an SVG.
+    Frame(HtmlFrame),
 }
 
 impl HtmlNode {
@@ -263,6 +263,17 @@ cast! {
     v: Str => Self::intern(&v)?,
 }
 
+/// Layouted content that will be embedded into HTML as an SVG.
+#[derive(Debug, Clone, Hash)]
+pub struct HtmlFrame {
+    /// The frame that will be displayed as an SVG.
+    pub inner: Frame,
+    /// The text size where the frame was defined. This is used to size the
+    /// frame with em units to make text in and outside of the frame sized
+    /// consistently.
+    pub text_size: Abs,
+}
+
 /// Defines syntactical properties of HTML tags, attributes, and text.
 pub mod charsets {
     /// Check whether a character is in a tag name.

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

@@ -8,6 +8,7 @@ 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 {
@@ -40,7 +41,7 @@ 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/introspection/introspector.rs

@@ -446,7 +446,7 @@ impl IntrospectorBuilder {
                 HtmlNode::Element(elem) => self.discover_in_html(sink, &elem.children),
                 HtmlNode::Frame(frame) => self.discover_in_frame(
                     sink,
-                    frame,
+                    &frame.inner,
                     NonZeroUsize::ONE,
                     Transform::identity(),
                 ),

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)]
@@ -490,7 +491,7 @@ 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)]
@@ -657,7 +658,7 @@ 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/grid/resolve.rs

@@ -22,6 +22,7 @@ use typst_syntax::Span;
 use typst_utils::NonZeroExt;
 
 use crate::introspection::SplitLocator;
+use crate::model::TableCellKind;
 
 /// Convert a grid to a cell grid.
 #[typst_macros::time(span = elem.span())]
@@ -217,6 +218,7 @@ impl ResolvableCell for Packed<TableCell> {
         breakable: bool,
         locator: Locator<'a>,
         styles: StyleChain,
+        kind: Smart<TableCellKind>,
     ) -> Cell<'a> {
         let cell = &mut *self;
         let colspan = cell.colspan(styles);
@@ -224,6 +226,8 @@ impl ResolvableCell for Packed<TableCell> {
         let breakable = cell.breakable(styles).unwrap_or(breakable);
         let fill = cell.fill(styles).unwrap_or_else(|| fill.clone());
 
+        let kind = cell.kind(styles).or(kind);
+
         let cell_stroke = cell.stroke(styles);
         let stroke_overridden =
             cell_stroke.as_ref().map(|side| matches!(side, Some(Some(_))));
@@ -267,6 +271,7 @@ impl ResolvableCell for Packed<TableCell> {
             }),
         );
         cell.push_breakable(Smart::Custom(breakable));
+        cell.push_kind(kind);
         Cell {
             body: self.pack(),
             locator,
@@ -312,6 +317,7 @@ impl ResolvableCell for Packed<GridCell> {
         breakable: bool,
         locator: Locator<'a>,
         styles: StyleChain,
+        _: Smart<TableCellKind>,
     ) -> Cell<'a> {
         let cell = &mut *self;
         let colspan = cell.colspan(styles);
@@ -522,6 +528,7 @@ pub trait ResolvableCell {
         breakable: bool,
         locator: Locator<'a>,
         styles: StyleChain,
+        kind: Smart<TableCellKind>,
     ) -> Cell<'a>;
 
     /// Returns this cell's column override.
@@ -1206,8 +1213,12 @@ impl<'x> CellGridResolver<'_, '_, 'x> {
         // a non-empty row.
         let mut first_available_row = 0;
 
+        let mut cell_kind: Smart<TableCellKind> = Smart::Auto;
+
         let (header_footer_items, simple_item) = match child {
             ResolvableGridChild::Header { repeat, level, span, items, .. } => {
+                cell_kind = Smart::Custom(TableCellKind::Header);
+
                 row_group_data = Some(RowGroupData {
                     range: None,
                     span,
@@ -1239,6 +1250,8 @@ impl<'x> CellGridResolver<'_, '_, 'x> {
                     bail!(span, "cannot have more than one footer");
                 }
 
+                cell_kind = Smart::Custom(TableCellKind::Footer);
+
                 row_group_data = Some(RowGroupData {
                     range: None,
                     span,
@@ -1447,7 +1460,7 @@ impl<'x> CellGridResolver<'_, '_, 'x> {
 
             // Let's resolve the cell so it can determine its own fields
             // based on its final position.
-            let cell = self.resolve_cell(cell, x, y, rowspan, cell_span)?;
+            let cell = self.resolve_cell(cell, x, y, rowspan, cell_span, cell_kind)?;
 
             if largest_index >= resolved_cells.len() {
                 // Ensure the length of the vector of resolved cells is
@@ -1542,6 +1555,10 @@ impl<'x> CellGridResolver<'_, '_, 'x> {
                     // and footers without having to loop through them each time.
                     // Cells themselves, unfortunately, still have to.
                     assert!(resolved_cells[*local_auto_index].is_none());
+                    let kind = match row_group.kind {
+                        RowGroupKind::Header => TableCellKind::Header,
+                        RowGroupKind::Footer => TableCellKind::Header,
+                    };
                     resolved_cells[*local_auto_index] =
                         Some(Entry::Cell(self.resolve_cell(
                             T::default(),
@@ -1549,6 +1566,7 @@ impl<'x> CellGridResolver<'_, '_, 'x> {
                             first_available_row,
                             1,
                             Span::detached(),
+                            Smart::Custom(kind),
                         )?));
 
                     group_start..group_end
@@ -1673,6 +1691,7 @@ impl<'x> CellGridResolver<'_, '_, 'x> {
                         y,
                         1,
                         Span::detached(),
+                        Smart::Auto,
                     )?))
                 }
             })
@@ -1918,6 +1937,7 @@ impl<'x> CellGridResolver<'_, '_, 'x> {
         y: usize,
         rowspan: usize,
         cell_span: Span,
+        kind: Smart<TableCellKind>,
     ) -> SourceResult<Cell<'x>>
     where
         T: ResolvableCell + Default,
@@ -1954,6 +1974,7 @@ impl<'x> CellGridResolver<'_, '_, 'x> {
             breakable,
             self.locator.next(&cell_span),
             self.styles,
+            kind,
         ))
     }
 }

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/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

@@ -321,7 +321,11 @@ impl Bibliography {
         for d in data.iter() {
             let library = decode_library(d)?;
             for entry in library {
-                match map.entry(Label::new(PicoStr::intern(entry.key()))) {
+                let label = Label::new(PicoStr::intern(entry.key()))
+                    .ok_or("bibliography contains entry with empty key")
+                    .at(d.source.span)?;
+
+                match map.entry(label) {
                     indexmap::map::Entry::Vacant(vacant) => {
                         vacant.insert(entry);
                     }
@@ -592,7 +596,7 @@ impl Works {
 
 /// Context for generating the bibliography.
 struct Generator<'a> {
-    /// The routines that is used to evaluate mathematical material in citations.
+    /// The routines that are used to evaluate mathematical material in citations.
     routines: &'a Routines,
     /// The world that is used to evaluate mathematical material in citations.
     world: Tracked<'a, dyn World + 'a>,
@@ -609,7 +613,7 @@ struct Generator<'a> {
 
 /// Details about a group of merged citations. All citations are put into groups
 /// of adjacent ones (e.g., `@foo @bar` will merge into a group of length two).
-/// Even single citations will be put into groups of length ones.
+/// Even single citations will be put into groups of length one.
 struct GroupInfo {
     /// The group's location.
     location: Location,
@@ -873,7 +877,8 @@ 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(dest, None);
                     }
                     StrResult::Ok(content)
                 })
@@ -1008,7 +1013,8 @@ 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(dest, None);
             }
         }
 

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

@@ -473,7 +473,7 @@ 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(Destination::Location(loc), None))
     }
 }
 
@@ -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(Destination::Location(loc), None)
             .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(dest.clone(), alt),
                 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.linked(dest, alt)
                 }
             }
         })

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 +18,8 @@ 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};
@@ -272,6 +273,7 @@ impl Show for Packed<OutlineElem> {
         let depth = self.depth(styles).unwrap_or(NonZeroUsize::MAX);
 
         // Build the outline entries.
+        let mut entries = vec![];
         for elem in elems {
             let Some(outlinable) = elem.with::<dyn Outlinable>() else {
                 bail!(span, "cannot outline {}", elem.func().name());
@@ -280,10 +282,13 @@ impl Show for Packed<OutlineElem> {
             let level = outlinable.level();
             if outlinable.outlined() && level <= depth {
                 let entry = OutlineEntry::new(level, elem);
-                seq.push(entry.pack().spanned(span));
+                entries.push(entry.pack().spanned(span));
             }
         }
 
+        // Wrap the entries into a marker for pdf tagging.
+        seq.push(OutlineBody::new(Content::sequence(entries)).pack());
+
         Ok(Content::sequence(seq))
     }
 }
@@ -306,6 +311,19 @@ impl LocalName for Packed<OutlineElem> {
     const KEY: &'static str = "outline";
 }
 
+/// Only used to mark
+#[elem(Locatable, Show)]
+pub struct OutlineBody {
+    #[required]
+    body: Content,
+}
+
+impl Show for Packed<OutlineBody> {
+    fn show(&self, _: &mut Engine, _: StyleChain) -> SourceResult<Content> {
+        Ok(self.body.clone())
+    }
+}
+
 /// Defines how an outline is indented.
 #[derive(Debug, Clone, PartialEq, Hash)]
 pub enum OutlineIndent {
@@ -364,7 +382,7 @@ 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.
@@ -417,8 +435,19 @@ impl Show for Packed<OutlineEntry> {
         let context = Context::new(None, Some(styles));
         let context = context.track();
 
+        // TODO: prefix should be wrapped in a `Lbl` structure element
         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(context, span, body, page)?;
         let block = if self.element.is::<EquationElem>() {
             let body = prefix.unwrap_or_default() + inner;
             BlockElem::new()
@@ -430,7 +459,7 @@ impl Show for Packed<OutlineEntry> {
         };
 
         let loc = self.element_location().at(span)?;
-        Ok(block.linked(Destination::Location(loc)))
+        Ok(block.linked(Destination::Location(loc), Some(alt)))
     }
 }
 
@@ -565,9 +594,10 @@ impl OutlineEntry {
     #[func(contextual)]
     pub fn inner(
         &self,
-        engine: &mut Engine,
         context: Tracked<Context>,
         span: Span,
+        body: Content,
+        page: Content,
     ) -> SourceResult<Content> {
         let styles = context.styles().at(span)?;
 
@@ -588,7 +618,7 @@ impl OutlineEntry {
             seq.push(TextElem::packed("\u{202B}"));
         }
 
-        seq.push(self.body().at(span)?);
+        seq.push(body);
 
         if rtl {
             // "Pop Directional Formatting"
@@ -613,7 +643,7 @@ 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

@@ -343,7 +343,8 @@ 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(Destination::Location(loc), None))
 }
 
 /// 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

@@ -1,6 +1,8 @@
 use std::num::{NonZeroU32, NonZeroUsize};
 use std::sync::Arc;
 
+use ecow::EcoString;
+use typst_macros::Cast;
 use typst_utils::NonZeroExt;
 
 use crate::diag::{bail, HintedStrResult, HintedString, SourceResult};
@@ -10,7 +12,7 @@ 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 +123,7 @@ 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.
@@ -237,6 +239,9 @@ pub struct TableElem {
     #[default(Celled::Value(Sides::splat(Some(Abs::pt(5.0).into()))))]
     pub inset: Celled<Sides<Option<Rel<Length>>>>,
 
+    // TODO: docs
+    pub summary: Option<EcoString>,
+
     /// The contents of the table cells, plus any extra table lines specified
     /// with the [`table.hline`]($table.hline) and
     /// [`table.vline`]($table.vline) elements.
@@ -531,7 +536,7 @@ 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)]
@@ -561,7 +566,7 @@ 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)]
@@ -604,7 +609,7 @@ 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`]($grid.hline.y).
@@ -649,7 +654,7 @@ pub struct TableHLine {
 /// use the [table's `stroke`]($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).
@@ -770,7 +775,7 @@ 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]
@@ -806,6 +811,12 @@ pub struct TableCell {
     #[fold]
     pub stroke: Sides<Option<Option<Arc<Stroke>>>>,
 
+    // TODO: feature gate
+    pub kind: Smart<TableCellKind>,
+
+    // TODO: feature gate
+    pub header_scope: Smart<TableHeaderScope>,
+
     /// Whether rows spanned by this cell can be placed in different pages.
     /// When equal to `{auto}`, a cell spanning only fixed-size rows is
     /// unbreakable, while a cell spanning at least one `{auto}`-sized row is
@@ -843,3 +854,18 @@ impl From<Content> for TableCell {
         value.unpack::<Self>().unwrap_or_else(Self::new)
     }
 }
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash, Cast)]
+pub enum TableHeaderScope {
+    Both,
+    Column,
+    Row,
+}
+
+#[derive(Debug, Default, Copy, Clone, Eq, PartialEq, Hash, Cast)]
+pub enum TableCellKind {
+    Header,
+    Footer,
+    #[default]
+    Data,
+}

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/pdf/accessibility.rs

@@ -0,0 +1,222 @@
+use ecow::EcoString;
+use typst_macros::{cast, elem, Cast};
+
+use crate::diag::SourceResult;
+use crate::engine::Engine;
+use crate::foundations::{Content, Packed, Show, StyleChain};
+use crate::introspection::Locatable;
+
+// TODO: docs
+#[elem(Locatable, Show)]
+pub struct PdfTagElem {
+    #[default(PdfTagKind::NonStruct)]
+    pub kind: PdfTagKind,
+
+    /// An alternate description.
+    pub alt: Option<EcoString>,
+    /// Exact replacement for this structure element and its children.
+    pub actual_text: Option<EcoString>,
+    /// The expanded form of an abbreviation/acronym.
+    pub expansion: Option<EcoString>,
+
+    /// The content to underline.
+    #[required]
+    pub body: Content,
+}
+
+impl Show for Packed<PdfTagElem> {
+    #[typst_macros::time(name = "pdf.tag", span = self.span())]
+    fn show(&self, _: &mut Engine, _: StyleChain) -> SourceResult<Content> {
+        Ok(self.body.clone())
+    }
+}
+
+// TODO: docs
+/// PDF structure elements
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub enum PdfTagKind {
+    // grouping elements
+    /// (Part)
+    Part,
+    /// (Article)
+    Art,
+    /// (Section)
+    Sect,
+    /// (Division)
+    Div,
+    /// (Block quotation)
+    BlockQuote,
+    /// (Caption)
+    Caption,
+    /// (Table of contents)
+    TOC,
+    /// (Table of contents item)
+    TOCI,
+    /// (Index)
+    Index,
+    /// (Nonstructural element)
+    NonStruct,
+    /// (Private element)
+    Private,
+
+    // paragraph like elements
+    /// (Heading)
+    H { title: Option<EcoString> },
+    /// (Heading level 1)
+    H1 { title: Option<EcoString> },
+    /// (Heading level 2)
+    H2 { title: Option<EcoString> },
+    /// (Heading level 3)
+    H4 { title: Option<EcoString> },
+    /// (Heading level 4)
+    H3 { title: Option<EcoString> },
+    /// (Heading level 5)
+    H5 { title: Option<EcoString> },
+    /// (Heading level 6)
+    H6 { title: Option<EcoString> },
+    /// (Paragraph)
+    P,
+
+    // list elements
+    /// (List)
+    L { numbering: ListNumbering },
+    /// (List item)
+    LI,
+    /// (Label)
+    Lbl,
+    /// (List body)
+    LBody,
+
+    // table elements
+    /// (Table)
+    Table,
+    /// (Table row)
+    TR,
+    /// (Table header)
+    TH { scope: TableHeaderScope },
+    /// (Table data cell)
+    TD,
+    /// (Table header row group)
+    THead,
+    /// (Table body row group)
+    TBody,
+    /// (Table footer row group)
+    TFoot,
+
+    // inline elements
+    /// (Span)
+    Span,
+    /// (Quotation)
+    Quote,
+    /// (Note)
+    Note,
+    /// (Reference)
+    Reference,
+    /// (Bibliography Entry)
+    BibEntry,
+    /// (Code)
+    Code,
+    /// (Link)
+    Link,
+    /// (Annotation)
+    Annot,
+
+    /// (Ruby)
+    Ruby,
+    /// (Ruby base text)
+    RB,
+    /// (Ruby annotation text)
+    RT,
+    /// (Ruby punctuation)
+    RP,
+
+    /// (Warichu)
+    Warichu,
+    /// (Warichu text)
+    WT,
+    /// (Warichu punctuation)
+    WP,
+
+    /// (Figure)
+    Figure,
+    /// (Formula)
+    Formula,
+    /// (Form)
+    Form,
+}
+
+cast! {
+    PdfTagKind,
+    self => match self {
+        PdfTagKind::Part => "part".into_value(),
+        _ => todo!(),
+    },
+    "part" => Self::Part,
+    // TODO
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum ListNumbering {
+    /// No numbering.
+    None,
+    /// Solid circular bullets.
+    Disc,
+    /// Open circular bullets.
+    Circle,
+    /// Solid square bullets.
+    Square,
+    /// Decimal numbers.
+    Decimal,
+    /// Lowercase Roman numerals.
+    LowerRoman,
+    /// Uppercase Roman numerals.
+    UpperRoman,
+    /// Lowercase letters.
+    LowerAlpha,
+    /// Uppercase letters.
+    UpperAlpha,
+}
+
+/// The scope of a table header cell.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum TableHeaderScope {
+    /// The header cell refers to the row.
+    Row,
+    /// The header cell refers to the column.
+    Column,
+    /// The header cell refers to both the row and the column.
+    Both,
+}
+
+/// Mark content as a PDF artifact.
+/// TODO: maybe generalize this and use it to mark html elements with `aria-hidden="true"`?
+#[elem(Locatable, Show)]
+pub struct ArtifactElem {
+    /// The artifact kind.
+    #[default(ArtifactKind::Other)]
+    pub kind: ArtifactKind,
+
+    /// The content that is an artifact.
+    #[required]
+    pub body: Content,
+}
+
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Hash, Cast)]
+pub enum ArtifactKind {
+    /// Page header artifacts.
+    Header,
+    /// Page footer artifacts.
+    Footer,
+    /// Other page artifacts.
+    Page,
+    /// Other artifacts.
+    #[default]
+    Other,
+}
+
+impl Show for Packed<ArtifactElem> {
+    #[typst_macros::time(name = "pdf.artifact", span = self.span())]
+    fn show(&self, _: &mut Engine, _: StyleChain) -> SourceResult<Content> {
+        Ok(self.body.clone())
+    }
+}

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

@@ -1,7 +1,9 @@
 //! PDF-specific functionality.
 
+mod accessibility;
 mod embed;
 
+pub use self::accessibility::*;
 pub use self::embed::*;
 
 use crate::foundations::{Module, Scope};
@@ -11,5 +13,7 @@ pub fn module() -> Module {
     let mut pdf = Scope::deduplicating();
     pdf.start_category(crate::Category::Pdf);
     pdf.define_elem::<EmbedElem>();
+    pdf.define_elem::<PdfTagElem>();
+    pdf.define_elem::<ArtifactElem>();
     Module::new("pdf", pdf)
 }

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

@@ -2,7 +2,11 @@ use smallvec::smallvec;
 
 use crate::diag::SourceResult;
 use crate::engine::Engine;
-use crate::foundations::{elem, Content, Packed, Show, Smart, StyleChain};
+use crate::foundations::{
+    elem, Content, NativeElement, Packed, Show, Smart, StyleChain, TargetElem,
+};
+use crate::html::{attr, tag, HtmlElem};
+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 +17,7 @@ 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.
     ///
@@ -81,6 +85,16 @@ pub struct UnderlineElem {
 impl Show for Packed<UnderlineElem> {
     #[typst_macros::time(name = "underline", span = self.span())]
     fn show(&self, _: &mut Engine, styles: StyleChain) -> SourceResult<Content> {
+        if TargetElem::target_in(styles).is_html() {
+            // Note: In modern HTML, `<u>` is not the underline element, but
+            // rather an "Unarticulated Annotation" element (see HTML spec
+            // 4.5.22). Using `text-decoration` instead is recommended by MDN.
+            return Ok(HtmlElem::new(tag::span)
+                .with_attr(attr::style, "text-decoration: underline")
+                .with_body(Some(self.body.clone()))
+                .pack());
+        }
+
         Ok(self.body.clone().styled(TextElem::set_deco(smallvec![Decoration {
             line: DecoLine::Underline {
                 stroke: self.stroke(styles).unwrap_or_default(),
@@ -99,7 +113,7 @@ impl Show for Packed<UnderlineElem> {
 /// ```example
 /// #overline[A line over text.]
 /// ```
-#[elem(Show)]
+#[elem(Locatable, Show)]
 pub struct OverlineElem {
     /// How to [stroke] the line.
     ///
@@ -173,6 +187,13 @@ pub struct OverlineElem {
 impl Show for Packed<OverlineElem> {
     #[typst_macros::time(name = "overline", span = self.span())]
     fn show(&self, _: &mut Engine, styles: StyleChain) -> SourceResult<Content> {
+        if TargetElem::target_in(styles).is_html() {
+            return Ok(HtmlElem::new(tag::span)
+                .with_attr(attr::style, "text-decoration: overline")
+                .with_body(Some(self.body.clone()))
+                .pack());
+        }
+
         Ok(self.body.clone().styled(TextElem::set_deco(smallvec![Decoration {
             line: DecoLine::Overline {
                 stroke: self.stroke(styles).unwrap_or_default(),
@@ -191,7 +212,7 @@ 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.
     ///
@@ -250,6 +271,10 @@ pub struct StrikeElem {
 impl Show for Packed<StrikeElem> {
     #[typst_macros::time(name = "strike", span = self.span())]
     fn show(&self, _: &mut Engine, styles: StyleChain) -> SourceResult<Content> {
+        if TargetElem::target_in(styles).is_html() {
+            return Ok(HtmlElem::new(tag::s).with_body(Some(self.body.clone())).pack());
+        }
+
         Ok(self.body.clone().styled(TextElem::set_deco(smallvec![Decoration {
             // Note that we do not support evade option for strikethrough.
             line: DecoLine::Strikethrough {
@@ -268,7 +293,7 @@ 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.
     ///
@@ -345,6 +370,12 @@ pub struct HighlightElem {
 impl Show for Packed<HighlightElem> {
     #[typst_macros::time(name = "highlight", span = self.span())]
     fn show(&self, _: &mut Engine, styles: StyleChain) -> SourceResult<Content> {
+        if TargetElem::target_in(styles).is_html() {
+            return Ok(HtmlElem::new(tag::mark)
+                .with_body(Some(self.body.clone()))
+                .pack());
+        }
+
         Ok(self.body.clone().styled(TextElem::set_deco(smallvec![Decoration {
             line: DecoLine::Highlight {
                 fill: self.fill(styles),

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

@@ -20,6 +20,7 @@ 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};
@@ -78,6 +79,7 @@ use crate::World;
     scope,
     title = "Raw Text / Code",
     Synthesize,
+    Locatable,
     Show,
     ShowSet,
     LocalName,
@@ -636,7 +638,7 @@ fn format_theme_error(error: syntect::LoadingError) -> LoadError {
 /// 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

@@ -6,6 +6,7 @@ use crate::foundations::{
     elem, Content, NativeElement, Packed, SequenceElem, Show, StyleChain, TargetElem,
 };
 use crate::html::{tag, HtmlElem};
+use crate::introspection::Locatable;
 use crate::layout::{Em, Length};
 use crate::text::{variant, SpaceElem, TextElem, TextSize};
 use crate::World;
@@ -18,7 +19,7 @@ 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.
     ///
@@ -84,7 +85,7 @@ 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/gradient.rs

@@ -1285,24 +1285,17 @@ fn process_stops(stops: &[Spanned<GradientStop>]) -> SourceResult<Vec<(Color, Ra
 /// Sample the stops at a given position.
 fn sample_stops(stops: &[(Color, Ratio)], mixing_space: ColorSpace, t: f64) -> Color {
     let t = t.clamp(0.0, 1.0);
-    let mut low = 0;
-    let mut high = stops.len();
+    let mut j = stops.partition_point(|(_, ratio)| ratio.get() < t);
 
-    while low < high {
-        let mid = (low + high) / 2;
-        if stops[mid].1.get() < t {
-            low = mid + 1;
-        } else {
-            high = mid;
+    if j == 0 {
+        while stops.get(j + 1).is_some_and(|(_, r)| r.is_zero()) {
+            j += 1;
         }
+        return stops[j].0;
     }
 
-    if low == 0 {
-        low = 1;
-    }
-
-    let (col_0, pos_0) = stops[low - 1];
-    let (col_1, pos_1) = stops[low];
+    let (col_0, pos_0) = stops[j - 1];
+    let (col_1, pos_1) = stops[j];
     let t = (t - pos_0.get()) / (pos_1.get() - pos_0.get());
 
     Color::mix_iter(

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, LoadSource, Loaded, 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

@@ -2,7 +2,6 @@ use std::collections::{BTreeMap, HashMap, HashSet};
 use std::num::NonZeroU64;
 
 use ecow::{eco_format, EcoVec};
-use krilla::annotation::Annotation;
 use krilla::configure::{Configuration, ValidationError, Validator};
 use krilla::destination::{NamedDestination, XyzDestination};
 use krilla::embed::EmbedError;
@@ -14,7 +13,7 @@ use krilla::{Document, SerializeSettings};
 use krilla_svg::render_svg_glyph;
 use typst_library::diag::{bail, error, SourceDiagnostic, SourceResult};
 use typst_library::foundations::{NativeElement, Repr};
-use typst_library::introspection::Location;
+use typst_library::introspection::{Location, Tag};
 use typst_library::layout::{
     Abs, Frame, FrameItem, GroupItem, PagedDocument, Size, Transform,
 };
@@ -25,11 +24,12 @@ use typst_syntax::Span;
 
 use crate::embed::embed_files;
 use crate::image::handle_image;
-use crate::link::handle_link;
+use crate::link::{handle_link, LinkAnnotation};
 use crate::metadata::build_metadata;
 use crate::outline::build_outline;
 use crate::page::PageLabelExt;
 use crate::shape::handle_shape;
+use crate::tags::{self, Tags};
 use crate::text::handle_text;
 use crate::util::{convert_path, display_font, AbsExt, TransformExt};
 use crate::PdfOptions;
@@ -46,7 +46,7 @@ pub fn convert(
         xmp_metadata: true,
         cmyk_profile: None,
         configuration: options.standards.config,
-        enable_tagging: false,
+        enable_tagging: !options.disable_tags,
         render_svg_glyph_fn: render_svg_glyph,
     };
 
@@ -54,6 +54,7 @@ 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 +67,7 @@ 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)
 }
@@ -115,9 +117,7 @@ fn convert_pages(gc: &mut GlobalContext, document: &mut Document) -> SourceResul
 
             surface.finish();
 
-            for annotation in fc.annotations {
-                page.add_annotation(annotation);
-            }
+            tags::add_annotations(gc, &mut page, fc.link_annotations);
         }
     }
 
@@ -171,14 +171,14 @@ impl State {
 /// Context needed for converting a single frame.
 pub(crate) struct FrameContext {
     states: Vec<State>,
-    annotations: Vec<Annotation>,
+    link_annotations: Vec<LinkAnnotation>,
 }
 
 impl FrameContext {
     pub(crate) fn new(size: Size) -> Self {
         Self {
             states: vec![State::new(size)],
-            annotations: vec![],
+            link_annotations: Vec::new(),
         }
     }
 
@@ -198,8 +198,18 @@ impl FrameContext {
         self.states.last_mut().unwrap()
     }
 
-    pub(crate) fn push_annotation(&mut self, annotation: Annotation) {
-        self.annotations.push(annotation);
+    pub(crate) fn get_link_annotation(
+        &mut self,
+        link_id: tags::LinkId,
+    ) -> Option<&mut LinkAnnotation> {
+        self.link_annotations
+            .iter_mut()
+            .rev()
+            .find(|annot| annot.id == link_id)
+    }
+
+    pub(crate) fn push_link_annotation(&mut self, annotation: LinkAnnotation) {
+        self.link_annotations.push(annotation);
     }
 }
 
@@ -225,6 +235,8 @@ 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 +256,8 @@ impl<'a> GlobalContext<'a> {
             image_spans: HashSet::new(),
             languages: BTreeMap::new(),
             page_index_converter,
+
+            tags: Tags::new(),
         }
     }
 }
@@ -278,8 +292,9 @@ 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(dest, size) => handle_link(fc, gc, dest, *size),
+            FrameItem::Tag(Tag::Start(elem)) => tags::handle_start(gc, elem),
+            FrameItem::Tag(Tag::End(loc, _)) => tags::handle_end(gc, *loc),
         }
 
         fc.pop();
@@ -294,7 +309,7 @@ pub(crate) fn handle_group(
     fc: &mut FrameContext,
     group: &GroupItem,
     surface: &mut Surface,
-    context: &mut GlobalContext,
+    gc: &mut GlobalContext,
 ) -> SourceResult<()> {
     fc.push();
     fc.state_mut().pre_concat(group.transform);
@@ -310,10 +325,12 @@ pub(crate) fn handle_group(
         .and_then(|p| p.transform(fc.state().transform.to_krilla()));
 
     if let Some(clip_path) = &clip_path {
+        let mut handle = tags::start_marked(gc, surface);
+        let surface = handle.surface();
         surface.push_clip_path(clip_path, &krilla::paint::FillRule::NonZero);
     }
 
-    handle_frame(fc, &group.frame, None, surface, context)?;
+    handle_frame(fc, &group.frame, None, surface, gc)?;
 
     if clip_path.is_some() {
         surface.pop();
@@ -576,6 +593,16 @@ fn convert_error(
             "{prefix} missing document date";
             hint: "set the date of the document"
         ),
+        ValidationError::DuplicateTagId(_id, loc) => {
+            // TODO: display the id and better error message
+            let span = to_span(*loc);
+            error!(span, "{prefix} duplicate tag id")
+        }
+        ValidationError::UnknownHeaderTagId(_id, loc) => {
+            // TODO: display the id and better error message
+            let span = to_span(*loc);
+            error!(span, "{prefix} unknown header tag id")
+        }
     }
 }
 

crates/typst-pdf/src/image.rs

@@ -4,6 +4,7 @@ use std::sync::{Arc, OnceLock};
 use image::{DynamicImage, EncodableLayout, GenericImageView, Rgba};
 use krilla::image::{BitsPerComponent, CustomImage, ImageColorspace};
 use krilla::surface::Surface;
+use krilla::tagging::SpanTag;
 use krilla_svg::{SurfaceExt, SvgSettings};
 use typst_library::diag::{bail, SourceResult};
 use typst_library::foundations::Smart;
@@ -14,6 +15,7 @@ use typst_library::visualize::{
 use typst_syntax::Span;
 
 use crate::convert::{FrameContext, GlobalContext};
+use crate::tags;
 use crate::util::{SizeExt, TransformExt};
 
 #[typst_macros::time(name = "handle image")]
@@ -30,12 +32,11 @@ pub(crate) fn handle_image(
 
     let interpolate = image.scaling() == Smart::Custom(ImageScaling::Smooth);
 
-    if let Some(alt) = image.alt() {
-        surface.start_alt_text(alt);
-    }
-
     gc.image_spans.insert(span);
 
+    let mut handle =
+        tags::start_span(gc, surface, SpanTag::empty().with_alt_text(image.alt()));
+    let surface = handle.surface();
     match image.kind() {
         ImageKind::Raster(raster) => {
             let (exif_transform, new_size) = exif_transform(raster, size);
@@ -62,10 +63,6 @@ pub(crate) fn handle_image(
         }
     }
 
-    if image.alt().is_some() {
-        surface.end_alt_text();
-    }
-
     surface.pop();
     surface.reset_location();
 

crates/typst-pdf/src/lib.rs

@@ -9,6 +9,7 @@ mod outline;
 mod page;
 mod paint;
 mod shape;
+mod tags;
 mod text;
 mod util;
 
@@ -53,6 +54,11 @@ pub struct PdfOptions<'a> {
     pub page_ranges: Option<PageRanges>,
     /// A list of PDF standards that Typst will enforce conformance with.
     pub standards: PdfStandards,
+    /// By default, even when not producing a `PDF/UA-1` document, a tagged PDF
+    /// document is written to provide a baseline of accessibility. In some
+    /// circumstances, for example when trying to reduce the size of a document,
+    /// it can be desirable to disable tagged PDF.
+    pub disable_tags: bool,
 }
 
 /// Encapsulates a list of compatible PDF standards.
@@ -104,6 +110,7 @@ impl PdfStandards {
                 PdfStandard::A_4 => set_validator(Validator::A4)?,
                 PdfStandard::A_4f => set_validator(Validator::A4F)?,
                 PdfStandard::A_4e => set_validator(Validator::A4E)?,
+                PdfStandard::Ua_1 => set_validator(Validator::UA1)?,
             }
         }
 
@@ -187,4 +194,7 @@ pub enum PdfStandard {
     /// PDF/A-4e.
     #[serde(rename = "a-4e")]
     A_4e,
+    /// PDF/UA-1.
+    #[serde(rename = "ua-1")]
+    Ua_1,
 }

crates/typst-pdf/src/link.rs

@@ -1,19 +1,90 @@
+use ecow::EcoString;
 use krilla::action::{Action, LinkAction};
-use krilla::annotation::{LinkAnnotation, Target};
+use krilla::annotation::Target;
+use krilla::configure::Validator;
 use krilla::destination::XyzDestination;
-use krilla::geom::Rect;
-use typst_library::layout::{Abs, Point, Size};
+use krilla::geom as kg;
+use typst_library::layout::{Abs, Point, Position, Size};
 use typst_library::model::Destination;
 
 use crate::convert::{FrameContext, GlobalContext};
+use crate::tags::{self, Placeholder, StackEntryKind, TagNode};
 use crate::util::{AbsExt, PointExt};
 
+pub(crate) struct LinkAnnotation {
+    pub(crate) id: tags::LinkId,
+    pub(crate) placeholder: Placeholder,
+    pub(crate) alt: Option<String>,
+    pub(crate) rect: kg::Rect,
+    pub(crate) quad_points: Vec<kg::Point>,
+    pub(crate) target: Target,
+}
+
 pub(crate) fn handle_link(
     fc: &mut FrameContext,
     gc: &mut GlobalContext,
     dest: &Destination,
     size: Size,
 ) {
+    let target = match dest {
+        Destination::Url(u) => {
+            Target::Action(Action::Link(LinkAction::new(u.to_string())))
+        }
+        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.
+                Target::Destination(krilla::destination::Destination::Named(nd.clone()))
+            } else {
+                let pos = gc.document.introspector.position(*loc);
+                match pos_to_target(gc, pos) {
+                    Some(target) => target,
+                    None => return,
+                }
+            }
+        }
+    };
+
+    let entry = gc.tags.stack.last_mut().expect("a link parent");
+    let StackEntryKind::Link(link_id, ref link) = entry.kind else {
+        unreachable!("expected a link parent")
+    };
+    let alt = link.alt.as_ref().map(EcoString::to_string);
+
+    let rect = to_rect(fc, size);
+    let quadpoints = quadpoints(rect);
+
+    // Unfortunately quadpoints still aren't well supported by most PDF readers,
+    // even by acrobat. Which is understandable since they were only introduced
+    // in PDF 1.6 (2005) /s
+    let should_use_quadpoints = gc.options.standards.config.validator() == Validator::UA1;
+    match fc.get_link_annotation(link_id) {
+        Some(annotation) if should_use_quadpoints => {
+            // Update the bounding box and add the quadpoints to an existing link annotation.
+            annotation.rect = bounding_rect(annotation.rect, rect);
+            annotation.quad_points.extend_from_slice(&quadpoints);
+        }
+        _ => {
+            let placeholder = gc.tags.reserve_placeholder();
+            gc.tags.push(TagNode::Placeholder(placeholder));
+            fc.push_link_annotation(LinkAnnotation {
+                id: link_id,
+                placeholder,
+                rect,
+                quad_points: quadpoints.to_vec(),
+                alt,
+                target,
+            });
+        }
+    }
+}
+
+// Compute the bounding box of the transformed link.
+fn to_rect(fc: &FrameContext, size: Size) -> kg::Rect {
     let mut min_x = Abs::inf();
     let mut min_y = Abs::inf();
     let mut max_x = -Abs::inf();
@@ -21,7 +92,6 @@ pub(crate) fn handle_link(
 
     let pos = Point::zero();
 
-    // Compute the bounding box of the transformed link.
     for point in [
         pos,
         pos + Point::with_x(size.x),
@@ -40,55 +110,32 @@ pub(crate) fn handle_link(
     let y1 = min_y.to_f32();
     let y2 = max_y.to_f32();
 
-    let rect = Rect::from_ltrb(x1, y1, x2, y2).unwrap();
+    kg::Rect::from_ltrb(x1, y1, x2, y2).unwrap()
+}
 
-    // TODO: Support quad points.
-
-    let pos = match dest {
-        Destination::Url(u) => {
-            fc.push_annotation(
-                LinkAnnotation::new(
-                    rect,
-                    None,
-                    Target::Action(Action::Link(LinkAction::new(u.to_string()))),
+fn bounding_rect(a: kg::Rect, b: kg::Rect) -> kg::Rect {
+    kg::Rect::from_ltrb(
+        a.left().min(b.left()),
+        a.top().min(b.top()),
+        a.right().max(b.right()),
+        a.bottom().max(b.bottom()),
     )
-                .into(),
-            );
-            return;
+    .unwrap()
 }
-        Destination::Position(p) => *p,
-        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;
-            } else {
-                gc.document.introspector.position(*loc)
-            }
-        }
-    };
 
+fn quadpoints(rect: kg::Rect) -> [kg::Point; 4] {
+    [
+        kg::Point::from_xy(rect.left(), rect.bottom()),
+        kg::Point::from_xy(rect.right(), rect.bottom()),
+        kg::Point::from_xy(rect.right(), rect.top()),
+        kg::Point::from_xy(rect.left(), rect.top()),
+    ]
+}
+
+fn pos_to_target(gc: &mut GlobalContext, pos: Position) -> Option<Target> {
     let page_index = pos.page.get() - 1;
-    if let Some(index) = gc.page_index_converter.pdf_page_index(page_index) {
-        fc.push_annotation(
-            LinkAnnotation::new(
-                rect,
-                None,
-                Target::Destination(krilla::destination::Destination::Xyz(
-                    XyzDestination::new(index, pos.point.to_krilla()),
-                )),
-            )
-            .into(),
-        );
-    }
+    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/shape.rs

@@ -5,8 +5,8 @@ use typst_library::visualize::{Geometry, Shape};
 use typst_syntax::Span;
 
 use crate::convert::{FrameContext, GlobalContext};
-use crate::paint;
 use crate::util::{convert_path, AbsExt, TransformExt};
+use crate::{paint, tags};
 
 #[typst_macros::time(name = "handle shape")]
 pub(crate) fn handle_shape(
@@ -16,6 +16,9 @@ pub(crate) fn handle_shape(
     gc: &mut GlobalContext,
     span: Span,
 ) -> SourceResult<()> {
+    let mut handle = tags::start_marked(gc, surface);
+    let surface = handle.surface();
+
     surface.set_location(span.into_raw().get());
     surface.push_transform(&fc.state().transform().to_krilla());
 

crates/typst-pdf/src/tags.rs

@@ -0,0 +1,625 @@
+use std::cell::OnceCell;
+use std::num::{NonZeroU32, NonZeroUsize};
+
+use ecow::EcoString;
+use krilla::page::Page;
+use krilla::surface::Surface;
+use krilla::tagging::{
+    ArtifactType, ContentTag, Identifier, Node, SpanTag, TableCellSpan, TableDataCell,
+    TableHeaderCell, Tag, TagBuilder, TagGroup, TagKind, TagTree,
+};
+use typst_library::foundations::{Content, LinkMarker, Packed, Smart, StyleChain};
+use typst_library::introspection::Location;
+use typst_library::layout::RepeatElem;
+use typst_library::model::{
+    Destination, FigureCaption, FigureElem, HeadingElem, Outlinable, OutlineBody,
+    OutlineEntry, TableCell, TableCellKind, TableElem, TableHeaderScope,
+};
+use typst_library::pdf::{ArtifactElem, ArtifactKind, PdfTagElem, PdfTagKind};
+use typst_library::visualize::ImageElem;
+
+use crate::convert::GlobalContext;
+use crate::link::LinkAnnotation;
+
+pub(crate) struct Tags {
+    /// The intermediary stack of nested tag groups.
+    pub(crate) stack: Vec<StackEntry>,
+    /// A list of placeholders corresponding to a [`TagNode::Placeholder`].
+    pub(crate) placeholders: Vec<OnceCell<Node>>,
+    pub(crate) in_artifact: Option<(Location, ArtifactKind)>,
+    pub(crate) link_id: LinkId,
+
+    /// The output.
+    pub(crate) tree: Vec<TagNode>,
+}
+
+pub(crate) struct StackEntry {
+    pub(crate) loc: Location,
+    pub(crate) kind: StackEntryKind,
+    pub(crate) nodes: Vec<TagNode>,
+}
+
+pub(crate) enum StackEntryKind {
+    Standard(Tag),
+    Outline(OutlineCtx),
+    OutlineEntry(Packed<OutlineEntry>),
+    Table(TableCtx),
+    TableCell(Packed<TableCell>),
+    Link(LinkId, Packed<LinkMarker>),
+}
+
+impl StackEntryKind {
+    pub(crate) fn as_standard_mut(&mut self) -> Option<&mut Tag> {
+        if let Self::Standard(v) = self {
+            Some(v)
+        } else {
+            None
+        }
+    }
+}
+
+pub(crate) struct OutlineCtx {
+    stack: Vec<OutlineSection>,
+}
+
+pub(crate) struct OutlineSection {
+    entries: Vec<TagNode>,
+}
+
+impl OutlineSection {
+    const fn new() -> Self {
+        OutlineSection { entries: Vec::new() }
+    }
+
+    fn push(&mut self, entry: TagNode) {
+        self.entries.push(entry);
+    }
+
+    fn into_tag(self) -> TagNode {
+        TagNode::Group(TagKind::TOC.into(), self.entries)
+    }
+}
+
+impl OutlineCtx {
+    fn new() -> Self {
+        Self { stack: Vec::new() }
+    }
+
+    fn insert(
+        &mut self,
+        outline_nodes: &mut Vec<TagNode>,
+        entry: Packed<OutlineEntry>,
+        nodes: Vec<TagNode>,
+    ) {
+        let expected_len = entry.level.get() - 1;
+        if self.stack.len() < expected_len {
+            self.stack.resize_with(expected_len, || OutlineSection::new());
+        } else {
+            while self.stack.len() > expected_len {
+                self.finish_section(outline_nodes);
+            }
+        }
+
+        let section_entry = TagNode::Group(TagKind::TOCI.into(), nodes);
+        self.push(outline_nodes, section_entry);
+    }
+
+    fn finish_section(&mut self, outline_nodes: &mut Vec<TagNode>) {
+        let sub_section = self.stack.pop().unwrap().into_tag();
+        self.push(outline_nodes, sub_section);
+    }
+
+    fn push(&mut self, outline_nodes: &mut Vec<TagNode>, entry: TagNode) {
+        match self.stack.last_mut() {
+            Some(section) => section.push(entry),
+            None => outline_nodes.push(entry),
+        }
+    }
+
+    fn build_outline(mut self, mut outline_nodes: Vec<TagNode>) -> Vec<TagNode> {
+        while self.stack.len() > 0 {
+            self.finish_section(&mut outline_nodes);
+        }
+        outline_nodes
+    }
+}
+
+pub(crate) struct TableCtx {
+    table: Packed<TableElem>,
+    rows: Vec<Vec<GridCell>>,
+}
+
+#[derive(Clone, Default)]
+enum GridCell {
+    Cell(TableCtxCell),
+    Spanned(usize, usize),
+    #[default]
+    Missing,
+}
+
+impl GridCell {
+    fn as_cell(&self) -> Option<&TableCtxCell> {
+        if let Self::Cell(v) = self {
+            Some(v)
+        } else {
+            None
+        }
+    }
+
+    fn into_cell(self) -> Option<TableCtxCell> {
+        if let Self::Cell(v) = self {
+            Some(v)
+        } else {
+            None
+        }
+    }
+}
+
+#[derive(Clone)]
+struct TableCtxCell {
+    rowspan: NonZeroUsize,
+    colspan: NonZeroUsize,
+    kind: TableCellKind,
+    header_scope: Smart<TableHeaderScope>,
+    nodes: Vec<TagNode>,
+}
+
+impl TableCtx {
+    fn new(table: Packed<TableElem>) -> Self {
+        Self { table: table.clone(), rows: Vec::new() }
+    }
+
+    fn insert(&mut self, cell: Packed<TableCell>, nodes: Vec<TagNode>) {
+        let x = cell.x(StyleChain::default()).unwrap_or_else(|| unreachable!());
+        let y = cell.y(StyleChain::default()).unwrap_or_else(|| unreachable!());
+        let rowspan = cell.rowspan(StyleChain::default());
+        let colspan = cell.colspan(StyleChain::default());
+        let kind = cell.kind(StyleChain::default());
+        let header_scope = cell.header_scope(StyleChain::default());
+
+        // The explicit cell kind takes precedence, but if it is `auto` and a
+        // scope was specified, make this a header cell.
+        let kind = match (kind, header_scope) {
+            (Smart::Custom(kind), _) => kind,
+            (Smart::Auto, Smart::Custom(_)) => TableCellKind::Header,
+            (Smart::Auto, Smart::Auto) => TableCellKind::Data,
+        };
+
+        // Extend the table grid to fit this cell.
+        let required_height = y + rowspan.get();
+        let required_width = x + colspan.get();
+        if self.rows.len() < required_height {
+            self.rows
+                .resize(required_height, vec![GridCell::Missing; required_width]);
+        }
+        let row = &mut self.rows[y];
+        if row.len() < required_width {
+            row.resize_with(required_width, || GridCell::Missing);
+        }
+
+        // Store references to the cell for all spanned cells.
+        for i in y..y + rowspan.get() {
+            for j in x..x + colspan.get() {
+                self.rows[i][j] = GridCell::Spanned(x, y);
+            }
+        }
+
+        self.rows[y][x] =
+            GridCell::Cell(TableCtxCell { rowspan, colspan, kind, header_scope, nodes });
+    }
+
+    fn build_table(self, mut nodes: Vec<TagNode>) -> Vec<TagNode> {
+        // Table layouting ensures that there are no overlapping cells, and that
+        // any gaps left by the user are filled with empty cells.
+
+        // Only generate row groups such as `THead`, `TFoot`, and `TBody` if
+        // there are no rows with mixed cell kinds.
+        let mut mixed_row_kinds = false;
+        let row_kinds = (self.rows.iter())
+            .map(|row| {
+                row.iter()
+                    .filter_map(|cell| match cell {
+                        GridCell::Cell(cell) => Some(cell),
+                        &GridCell::Spanned(x, y) => self.rows[y][x].as_cell(),
+                        GridCell::Missing => None,
+                    })
+                    .map(|cell| cell.kind)
+                    .reduce(|a, b| {
+                        if a != b {
+                            mixed_row_kinds = true;
+                        }
+                        a
+                    })
+                    .expect("tables must have at least one column")
+            })
+            .collect::<Vec<_>>();
+
+        let Some(mut chunk_kind) = row_kinds.first().copied() else {
+            return nodes;
+        };
+        let mut row_chunk = Vec::new();
+        for (row, row_kind) in self.rows.into_iter().zip(row_kinds) {
+            let row_nodes = row
+                .into_iter()
+                .filter_map(|cell| {
+                    let cell = cell.into_cell()?;
+                    let span = TableCellSpan {
+                        rows: cell.rowspan.get() as i32,
+                        cols: cell.colspan.get() as i32,
+                    };
+                    let tag = match cell.kind {
+                        TableCellKind::Header => {
+                            let scope = match cell.header_scope {
+                                Smart::Custom(scope) => table_header_scope(scope),
+                                Smart::Auto => krilla::tagging::TableHeaderScope::Column,
+                            };
+                            TagKind::TH(TableHeaderCell::new(scope).with_span(span))
+                        }
+                        TableCellKind::Footer | TableCellKind::Data => {
+                            TagKind::TD(TableDataCell::new().with_span(span))
+                        }
+                    };
+
+                    Some(TagNode::Group(tag.into(), cell.nodes))
+                })
+                .collect();
+
+            let row = TagNode::Group(TagKind::TR.into(), row_nodes);
+
+            // Push the `TR` tags directly.
+            if mixed_row_kinds {
+                nodes.push(row);
+                continue;
+            }
+
+            // Generate row groups.
+            if row_kind != chunk_kind {
+                let tag = match chunk_kind {
+                    TableCellKind::Header => TagKind::THead,
+                    TableCellKind::Footer => TagKind::TFoot,
+                    TableCellKind::Data => TagKind::TBody,
+                };
+                nodes.push(TagNode::Group(tag.into(), std::mem::take(&mut row_chunk)));
+
+                chunk_kind = row_kind;
+            }
+            row_chunk.push(row);
+        }
+
+        if !row_chunk.is_empty() {
+            let tag = match chunk_kind {
+                TableCellKind::Header => TagKind::THead,
+                TableCellKind::Footer => TagKind::TFoot,
+                TableCellKind::Data => TagKind::TBody,
+            };
+            nodes.push(TagNode::Group(tag.into(), row_chunk));
+        }
+
+        nodes
+    }
+}
+
+#[derive(Clone)]
+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, PartialEq, Eq, Hash)]
+pub(crate) struct LinkId(u32);
+
+#[derive(Clone, Copy)]
+pub(crate) struct Placeholder(usize);
+
+impl Tags {
+    pub(crate) fn new() -> Self {
+        Self {
+            stack: Vec::new(),
+            placeholders: Vec::new(),
+            in_artifact: None,
+
+            tree: Vec::new(),
+            link_id: LinkId(0),
+        }
+    }
+
+    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")
+    }
+
+    /// Returns the current parent's list of children and the structure type ([Tag]).
+    /// In case of the document root the structure type will be `None`.
+    pub(crate) fn parent(&mut self) -> Option<&mut StackEntryKind> {
+        self.stack.last_mut().map(|e| &mut e.kind)
+    }
+
+    pub(crate) fn push(&mut self, node: TagNode) {
+        if let Some(entry) = self.stack.last_mut() {
+            entry.nodes.push(node);
+        } else {
+            self.tree.push(node);
+        }
+    }
+
+    pub(crate) fn build_tree(&mut self) -> TagTree {
+        let children = std::mem::take(&mut self.tree)
+            .into_iter()
+            .map(|node| self.resolve_node(node))
+            .collect::<Vec<_>>();
+        TagTree::from(children)
+    }
+
+    /// Resolves [`Placeholder`] nodes.
+    fn resolve_node(&mut self, node: TagNode) -> Node {
+        match node {
+            TagNode::Group(tag, nodes) => {
+                let children = nodes
+                    .into_iter()
+                    .map(|node| self.resolve_node(node))
+                    .collect::<Vec<_>>();
+                Node::Group(TagGroup::with_children(tag, children))
+            }
+            TagNode::Leaf(identifier) => Node::Leaf(identifier),
+            TagNode::Placeholder(placeholder) => self.take_placeholder(placeholder),
+        }
+    }
+
+    fn context_supports(&self, _tag: &StackEntryKind) -> bool {
+        // TODO: generate using: https://pdfa.org/resource/iso-ts-32005-hierarchical-inclusion-rules/
+        true
+    }
+
+    fn next_link_id(&mut self) -> LinkId {
+        self.link_id.0 += 1;
+        self.link_id
+    }
+}
+
+/// Automatically calls [`Surface::end_tagged`] when dropped.
+pub(crate) struct TagHandle<'a, 'b> {
+    surface: &'b mut Surface<'a>,
+}
+
+impl Drop for TagHandle<'_, '_> {
+    fn drop(&mut self) {
+        self.surface.end_tagged();
+    }
+}
+
+impl<'a> TagHandle<'a, '_> {
+    pub(crate) fn surface<'c>(&'c mut self) -> &'c mut Surface<'a> {
+        &mut self.surface
+    }
+}
+
+/// Returns a [`TagHandle`] that automatically calls [`Surface::end_tagged`]
+/// when dropped.
+pub(crate) fn start_marked<'a, 'b>(
+    gc: &mut GlobalContext,
+    surface: &'b mut Surface<'a>,
+) -> TagHandle<'a, 'b> {
+    start_content(gc, surface, ContentTag::Other)
+}
+
+/// Returns a [`TagHandle`] that automatically calls [`Surface::end_tagged`]
+/// when dropped.
+pub(crate) fn start_span<'a, 'b>(
+    gc: &mut GlobalContext,
+    surface: &'b mut Surface<'a>,
+    span: SpanTag,
+) -> TagHandle<'a, 'b> {
+    start_content(gc, surface, ContentTag::Span(span))
+}
+
+fn start_content<'a, 'b>(
+    gc: &mut GlobalContext,
+    surface: &'b mut Surface<'a>,
+    content: ContentTag,
+) -> TagHandle<'a, 'b> {
+    let content = if let Some((_, kind)) = gc.tags.in_artifact {
+        let ty = artifact_type(kind);
+        ContentTag::Artifact(ty)
+    } else if let Some(StackEntryKind::Table(_)) = gc.tags.stack.last().map(|e| &e.kind) {
+        // Mark any direct child of a table as an aritfact. Any real content
+        // will be wrapped inside a `TableCell`.
+        ContentTag::Artifact(ArtifactType::Other)
+    } else {
+        content
+    };
+    let id = surface.start_tagged(content);
+    gc.tags.push(TagNode::Leaf(id));
+    TagHandle { surface }
+}
+
+/// Add all annotations that were found in the page frame.
+pub(crate) fn add_annotations(
+    gc: &mut GlobalContext,
+    page: &mut Page,
+    annotations: Vec<LinkAnnotation>,
+) {
+    for annotation in annotations.into_iter() {
+        let LinkAnnotation { id: _, placeholder, alt, rect, quad_points, target } =
+            annotation;
+        let annot = krilla::annotation::Annotation::new_link(
+            krilla::annotation::LinkAnnotation::new(rect, Some(quad_points), target),
+            alt,
+        );
+        let annot_id = page.add_tagged_annotation(annot);
+        gc.tags.init_placeholder(placeholder, Node::Leaf(annot_id));
+    }
+}
+
+pub(crate) fn handle_start(gc: &mut GlobalContext, elem: &Content) {
+    if gc.tags.in_artifact.is_some() {
+        // Don't nest artifacts
+        return;
+    }
+
+    let loc = elem.location().unwrap();
+
+    if let Some(artifact) = elem.to_packed::<ArtifactElem>() {
+        let kind = artifact.kind(StyleChain::default());
+        start_artifact(gc, loc, kind);
+        return;
+    } else if let Some(_) = elem.to_packed::<RepeatElem>() {
+        start_artifact(gc, loc, ArtifactKind::Other);
+        return;
+    }
+
+    let tag: Tag = if let Some(pdf_tag) = elem.to_packed::<PdfTagElem>() {
+        let kind = pdf_tag.kind(StyleChain::default());
+        match kind {
+            PdfTagKind::Part => TagKind::Part.into(),
+            _ => todo!(),
+        }
+    } else if let Some(heading) = elem.to_packed::<HeadingElem>() {
+        let level = heading.level().try_into().unwrap_or(NonZeroU32::MAX);
+        let name = heading.body.plain_text().to_string();
+        TagKind::Hn(level, Some(name)).into()
+    } else if let Some(_) = elem.to_packed::<OutlineBody>() {
+        push_stack(gc, loc, StackEntryKind::Outline(OutlineCtx::new()));
+        return;
+    } else if let Some(entry) = elem.to_packed::<OutlineEntry>() {
+        push_stack(gc, loc, StackEntryKind::OutlineEntry(entry.clone()));
+        return;
+    } else if let Some(_) = elem.to_packed::<FigureElem>() {
+        let alt = None; // TODO
+        TagKind::Figure.with_alt_text(alt)
+    } else if let Some(image) = elem.to_packed::<ImageElem>() {
+        let alt = image.alt(StyleChain::default()).map(|s| s.to_string());
+
+        let figure_tag = (gc.tags.parent())
+            .and_then(StackEntryKind::as_standard_mut)
+            .filter(|tag| tag.kind == TagKind::Figure);
+        if let Some(figure_tag) = figure_tag {
+            // Set alt text of outer figure tag, if not present.
+            if figure_tag.alt_text.is_none() {
+                figure_tag.alt_text = alt;
+            }
+            return;
+        } else {
+            TagKind::Figure.with_alt_text(alt)
+        }
+    } else if let Some(_) = elem.to_packed::<FigureCaption>() {
+        TagKind::Caption.into()
+    } else if let Some(table) = elem.to_packed::<TableElem>() {
+        push_stack(gc, loc, StackEntryKind::Table(TableCtx::new(table.clone())));
+        return;
+    } else if let Some(cell) = elem.to_packed::<TableCell>() {
+        push_stack(gc, loc, StackEntryKind::TableCell(cell.clone()));
+        return;
+    } else if let Some(link) = elem.to_packed::<LinkMarker>() {
+        let link_id = gc.tags.next_link_id();
+        push_stack(gc, loc, StackEntryKind::Link(link_id, link.clone()));
+        return;
+    } else {
+        return;
+    };
+
+    push_stack(gc, loc, StackEntryKind::Standard(tag));
+}
+
+fn push_stack(gc: &mut GlobalContext, loc: Location, kind: StackEntryKind) {
+    if !gc.tags.context_supports(&kind) {
+        // TODO: error or warning?
+    }
+
+    gc.tags.stack.push(StackEntry { loc, kind, nodes: Vec::new() });
+}
+
+pub(crate) fn handle_end(gc: &mut GlobalContext, loc: Location) {
+    if let Some((l, _)) = gc.tags.in_artifact {
+        if l == loc {
+            gc.tags.in_artifact = None;
+        }
+        return;
+    }
+
+    let Some(entry) = gc.tags.stack.pop_if(|e| e.loc == loc) else {
+        return;
+    };
+
+    let node = match entry.kind {
+        StackEntryKind::Standard(tag) => TagNode::Group(tag, entry.nodes),
+        StackEntryKind::Outline(ctx) => {
+            let nodes = ctx.build_outline(entry.nodes);
+            TagNode::Group(TagKind::TOC.into(), nodes)
+        }
+        StackEntryKind::OutlineEntry(outline_entry) => {
+            let parent = gc.tags.stack.last_mut().expect("outline");
+            let StackEntryKind::Outline(outline_ctx) = &mut parent.kind else {
+                unreachable!("expected outline")
+            };
+
+            outline_ctx.insert(&mut parent.nodes, outline_entry, entry.nodes);
+
+            return;
+        }
+        StackEntryKind::Table(ctx) => {
+            let summary = ctx.table.summary(StyleChain::default()).map(EcoString::into);
+            let nodes = ctx.build_table(entry.nodes);
+            TagNode::Group(TagKind::Table(summary).into(), nodes)
+        }
+        StackEntryKind::TableCell(cell) => {
+            let parent = gc.tags.stack.last_mut().expect("table");
+            let StackEntryKind::Table(table_ctx) = &mut parent.kind else {
+                unreachable!("expected table")
+            };
+
+            table_ctx.insert(cell, entry.nodes);
+
+            return;
+        }
+        StackEntryKind::Link(_, link) => {
+            let alt = link.alt.as_ref().map(EcoString::to_string);
+            let tag = TagKind::Link.with_alt_text(alt);
+            let mut node = TagNode::Group(tag, entry.nodes);
+            // Wrap link in reference tag, if it's not a url.
+            if let Destination::Position(_) | Destination::Location(_) = link.dest {
+                node = TagNode::Group(TagKind::Reference.into(), vec![node]);
+            }
+            node
+        }
+    };
+
+    gc.tags.push(node);
+}
+
+fn start_artifact(gc: &mut GlobalContext, loc: Location, kind: ArtifactKind) {
+    gc.tags.in_artifact = Some((loc, kind));
+}
+
+fn table_header_scope(scope: TableHeaderScope) -> krilla::tagging::TableHeaderScope {
+    match scope {
+        TableHeaderScope::Both => krilla::tagging::TableHeaderScope::Both,
+        TableHeaderScope::Column => krilla::tagging::TableHeaderScope::Column,
+        TableHeaderScope::Row => krilla::tagging::TableHeaderScope::Row,
+    }
+}
+
+fn artifact_type(kind: ArtifactKind) -> ArtifactType {
+    match kind {
+        ArtifactKind::Header => ArtifactType::Header,
+        ArtifactKind::Footer => ArtifactType::Footer,
+        ArtifactKind::Page => ArtifactType::Page,
+        ArtifactKind::Other => ArtifactType::Other,
+    }
+}

crates/typst-pdf/src/text.rs

@@ -3,6 +3,7 @@ use std::sync::Arc;
 
 use bytemuck::TransparentWrapper;
 use krilla::surface::{Location, Surface};
+use krilla::tagging::SpanTag;
 use krilla::text::GlyphId;
 use typst_library::diag::{bail, SourceResult};
 use typst_library::layout::Size;
@@ -11,8 +12,8 @@ use typst_library::visualize::FillRule;
 use typst_syntax::Span;
 
 use crate::convert::{FrameContext, GlobalContext};
-use crate::paint;
 use crate::util::{display_font, AbsExt, TransformExt};
+use crate::{paint, tags};
 
 #[typst_macros::time(name = "handle text")]
 pub(crate) fn handle_text(
@@ -23,6 +24,10 @@ pub(crate) fn handle_text(
 ) -> SourceResult<()> {
     *gc.languages.entry(t.lang).or_insert(0) += t.glyphs.len();
 
+    let mut handle =
+        tags::start_span(gc, surface, SpanTag::empty().with_actual_text(Some(&t.text)));
+    let surface = handle.surface();
+
     let font = convert_font(gc, t.font.clone())?;
     let fill = paint::convert_fill(
         gc,

crates/typst-realize/src/lib.rs

@@ -18,7 +18,7 @@ use typst_library::foundations::{
     SequenceElem, Show, ShowSet, Style, StyleChain, StyledElem, Styles, SymbolElem,
     Synthesize, Transformation,
 };
-use typst_library::html::{tag, HtmlElem};
+use typst_library::html::{tag, FrameElem, HtmlElem};
 use typst_library::introspection::{Locatable, SplitLocator, Tag, TagElem};
 use typst_library::layout::{
     AlignElem, BoxElem, HElem, InlineElem, PageElem, PagebreakElem, VElem,
@@ -237,9 +237,9 @@ fn visit<'a>(
         return Ok(());
     }
 
-    // Transformations for math content based on the realization kind. Needs
+    // Transformations for content based on the realization kind. Needs
     // to happen before show rules.
-    if visit_math_rules(s, content, styles)? {
+    if visit_kind_rules(s, content, styles)? {
         return Ok(());
     }
 
@@ -280,9 +280,8 @@ fn visit<'a>(
     Ok(())
 }
 
-// Handles special cases for math in normal content and nested equations in
-// math.
-fn visit_math_rules<'a>(
+// Handles transformations based on the realization kind.
+fn visit_kind_rules<'a>(
     s: &mut State<'a, '_, '_, '_>,
     content: &'a Content,
     styles: StyleChain<'a>,
@@ -335,6 +334,13 @@ fn visit_math_rules<'a>(
         }
     }
 
+    if !s.kind.is_html() {
+        if let Some(elem) = content.to_packed::<FrameElem>() {
+            visit(s, &elem.body, styles)?;
+            return Ok(true);
+        }
+    }
+
     Ok(false)
 }
 

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!(),
             };
 

crates/typst-syntax/src/ast.rs

@@ -724,6 +724,8 @@ node! {
 
 impl<'a> Ref<'a> {
     /// Get the target.
+    ///
+    /// Will not be empty.
     pub fn target(self) -> &'a str {
         self.0
             .children()

crates/typst-syntax/src/lexer.rs

@@ -185,7 +185,7 @@ impl Lexer<'_> {
             'h' if self.s.eat_if("ttp://") => self.link(),
             'h' if self.s.eat_if("ttps://") => self.link(),
             '<' if self.s.at(is_id_continue) => self.label(),
-            '@' => self.ref_marker(),
+            '@' if self.s.at(is_id_continue) => self.ref_marker(),
 
             '.' if self.s.eat_if("..") => SyntaxKind::Shorthand,
             '-' if self.s.eat_if("--") => SyntaxKind::Shorthand,

docs/guides/guide-for-latex-users.md

@@ -256,8 +256,8 @@ In Typst, the same function can be used both to affect the appearance for the
 remainder of the document, a block (or scope), or just its arguments. For
 example, `[#text(weight: "bold")[bold text]]` will only embolden its argument,
 while `[#set text(weight: "bold")]` will embolden any text until the end of the
-current block, or, if there is none, document. The effects of a function are
-immediately obvious based on whether it is used in a call or a
+current block, or the end of the document, if there is none. The effects of a
+function are immediately obvious based on whether it is used in a call or a
 [set rule.]($styling/#set-rules)
 
 ```example

docs/guides/page-setup.md

@@ -206,7 +206,6 @@ label exists on the current page:
 ```typ
 >>> #set page("a5", margin: (x: 2.5cm, y: 3cm))
 #set page(header: context {
-  let page-counter =
   let matches = query(<big-table>)
   let current = counter(page).get()
   let has-table = matches.any(m =>
@@ -218,7 +217,7 @@ label exists on the current page:
     #h(1fr)
     National Academy of Sciences
   ]
-}))
+})
 
 #lorem(100)
 #pagebreak()

docs/reference/groups.yml

@@ -181,11 +181,7 @@
     [`sys.version`]($category/foundations/sys) can also be very useful.
 
     ```typ
-    #let tiling = if "tiling" in dictionary(std) {
-      tiling
-    } else {
-      pattern
-    }
+    #let tiling = if "tiling" in std { tiling } else { pattern }
 
     ...
     ```

docs/src/lib.rs

@@ -720,18 +720,12 @@ fn symbols_model(resolver: &dyn Resolver, group: &GroupData) -> SymbolsModel {
             }
         };
 
-        for (variant, c) in symbol.variants() {
+        for (variant, c, deprecation) in symbol.variants() {
             let shorthand = |list: &[(&'static str, char)]| {
                 list.iter().copied().find(|&(_, x)| x == c).map(|(s, _)| s)
             };
 
             let name = complete(variant);
-            let deprecation = match name.as_str() {
-                "integral.sect" => {
-                    Some("`integral.sect` is deprecated, use `integral.inter` instead")
-                }
-                _ => binding.deprecation(),
-            };
 
             list.push(SymbolModel {
                 name,
@@ -742,10 +736,10 @@ fn symbols_model(resolver: &dyn Resolver, group: &GroupData) -> SymbolsModel {
                 accent: typst::math::Accent::combine(c).is_some(),
                 alternates: symbol
                     .variants()
-                    .filter(|(other, _)| other != &variant)
-                    .map(|(other, _)| complete(other))
+                    .filter(|(other, _, _)| other != &variant)
+                    .map(|(other, _, _)| complete(other))
                     .collect(),
-                deprecation,
+                deprecation: deprecation.or_else(|| binding.deprecation()),
             });
         }
     }

tests/ref/html/html-deco.html

@@ -0,0 +1,11 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <meta charset="utf-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+  </head>
+  <body>
+    <p><s>Struck</s> <mark>Highlighted</mark> <span style="text-decoration: underline">Underlined</span> <span style="text-decoration: overline">Overlined</span></p>
+    <p><span style="text-decoration: overline"><span style="text-decoration: underline"><mark><s>Mixed</s></mark></span></span></p>
+  </body>
+</html>

tests/suite/foundations/label.typ

@@ -92,3 +92,7 @@ _Visible_
 --- label-non-existent-error ---
 // Error: 5-10 sequence does not have field "label"
 #[].label
+
+--- label-empty ---
+// Error: 23-32 label name must not be empty
+= Something to label #label("")

tests/suite/html/frame.typ

@@ -0,0 +1,8 @@
+// No proper HTML tests here yet because we don't want to test SVG export just
+// yet. We'll definitely add tests at some point.
+
+--- html-frame-in-layout ---
+// Ensure that HTML frames are transparent in layout. This is less important for
+// actual paged export than for _nested_ HTML frames, which take the same code
+// path.
+#html.frame[A]

tests/suite/layout/align.typ

@@ -34,7 +34,7 @@ To the right! Where the sunlight peeks behind the mountain.
 #align(start)[Start]
 #align(end)[Ende]
 
-#set text(lang: "ar")
+#set text(lang: "ar", font: "Noto Sans Arabic")
 #align(start)[يبدأ]
 #align(end)[نهاية]
 

tests/suite/layout/inline/bidi.typ

@@ -45,6 +45,7 @@ Lריווח #h(1cm) R
 
 --- bidi-whitespace-reset ---
 // Test whether L1 whitespace resetting destroys stuff.
+#set text(font: ("Libertinus Serif", "Noto Sans Arabic"))
 الغالب #h(70pt) ن#" "ة
 
 --- bidi-explicit-dir ---
@@ -87,7 +88,7 @@ Lריווח #h(1cm) R
   columns: (1fr, 1fr),
   lines(6),
   [
-    #text(lang: "ar")[مجرد نص مؤقت لأغراض العرض التوضيحي. ]
+    #text(lang: "ar", font: ("Libertinus Serif", "Noto Sans Arabic"))[مجرد نص مؤقت لأغراض العرض التوضيحي. ]
     #text(lang: "ar")[سلام]
   ],
 )

tests/suite/layout/inline/shaping.typ

@@ -29,6 +29,7 @@ ABCअपार्टमेंट
 \ ט
 
 --- shaping-font-fallback ---
+#set text(font: ("Libertinus Serif", "Noto Sans Arabic"))
 // Font fallback for emoji.
 A😀B
 

tests/suite/layout/inline/text.typ

@@ -80,7 +80,7 @@ I'm in#text(tracking: 0.15em + 1.5pt)[ spaace]!
 
 --- text-tracking-arabic ---
 // Test tracking in arabic text (makes no sense whatsoever)
-#set text(tracking: 0.3em)
+#set text(tracking: 0.3em, font: "Noto Sans Arabic")
 النص
 
 --- text-spacing ---

tests/suite/layout/repeat.typ

@@ -17,7 +17,7 @@
 
 --- repeat-dots-rtl ---
 // Test dots with RTL.
-#set text(lang: "ar")
+#set text(lang: "ar", font: ("Libertinus Serif", "Noto Sans Arabic"))
 مقدمة #box(width: 1fr, repeat[.]) 15
 
 --- repeat-empty ---
@@ -35,7 +35,7 @@ A#box(width: 1fr, repeat(rect(width: 6em, height: 0.7em)))B
 #set align(center)
 A#box(width: 1fr, repeat(rect(width: 6em, height: 0.7em)))B
 
-#set text(dir: rtl)
+#set text(dir: rtl, font: "Noto Sans Arabic")
 ريجين#box(width: 1fr, repeat(rect(width: 4em, height: 0.7em)))سون
 
 --- repeat-unrestricted ---

tests/suite/math/attach.typ

@@ -121,8 +121,8 @@ $a scripts(=)^"def" b quad a scripts(lt.eq)_"really" b quad a scripts(arrow.r.lo
 
 --- math-attach-integral ---
 // Test default of scripts attachments on integrals at display size.
-$ integral.sect_a^b  quad \u{2a1b}_a^b quad limits(\u{2a1b})_a^b $
-$integral.sect_a^b quad \u{2a1b}_a^b quad limits(\u{2a1b})_a^b$
+$ integral.inter_a^b  quad \u{2a1b}_a^b quad limits(\u{2a1b})_a^b $
+$integral.inter_a^b quad \u{2a1b}_a^b quad limits(\u{2a1b})_a^b$
 
 --- math-attach-large-operator ---
 // Test default of limit attachments on large operators at display size only.

tests/suite/model/bibliography.typ

@@ -75,6 +75,14 @@ Now we have multiple bibliographies containing @glacier-melt @keshav2007read
 // Error: 2-62 CSL style "Alphanumeric" is not suitable for bibliographies
 #bibliography("/assets/bib/works.bib", style: "alphanumeric")
 
+--- bibliography-empty-key ---
+#let src = ```yaml
+"":
+  type: Book
+```
+// Error: 15-30 bibliography contains entry with empty key
+#bibliography(bytes(src.text))
+
 --- issue-4618-bibliography-set-heading-level ---
 // Test that the bibliography block's heading is set to 2 by the show rule,
 // and therefore should be rendered like a level-2 heading. Notably, this

tests/suite/model/cite.typ

@@ -147,3 +147,16 @@ B #cite(<netwok>) #cite(<arrgh>).
 // Error: 7-17 expected label, found string
 // Hint: 7-17 use `label("%@&#*!\\")` to create a label
 #cite("%@&#*!\\")
+
+--- issue-5775-cite-order-rtl ---
+// Test citation order in RTL text.
+#set page(width: 300pt)
+#set text(font: ("Libertinus Serif", "Noto Sans Arabic"))
+@netwok
+aaa
+این است
+@tolkien54
+و این یکی هست
+@arrgh
+
+#bibliography("/assets/bib/works.bib")

tests/suite/model/par.typ

@@ -231,7 +231,7 @@ Welcome \ here. Does this work well?
 
 --- par-hanging-indent-rtl ---
 #set par(hanging-indent: 2em)
-#set text(dir: rtl)
+#set text(dir: rtl, font: ("Libertinus Serif", "Noto Sans Arabic"))
 لآن وقد أظلم الليل وبدأت النجوم
 تنضخ وجه الطبيعة التي أعْيَتْ من طول ما انبعثت في النهار
 

tests/suite/model/quote.typ

@@ -2,6 +2,7 @@
 
 --- quote-dir-author-pos ---
 // Text direction affects author positioning
+#set text(font: ("Libertinus Serif", "Noto Sans Arabic"))
 And I quote: #quote(attribution: [René Descartes])[cogito, ergo sum].
 
 #set text(lang: "ar")
@@ -9,6 +10,7 @@ And I quote: #quote(attribution: [René Descartes])[cogito, ergo sum].
 
 --- quote-dir-align ---
 // Text direction affects block alignment
+#set text(font: ("Libertinus Serif", "Noto Sans Arabic"))
 #set quote(block: true)
 #quote(attribution: [René Descartes])[cogito, ergo sum]
 

tests/suite/model/ref.typ

@@ -86,3 +86,14 @@ Text seen on #ref(<text>, form: "page", supplement: "Page").
 // Test reference with non-whitespace before it.
 #figure[] <1>
 #test([(#ref(<1>))], [(@1)])
+
+--- ref-to-empty-label-not-possible ---
+// @ without any following label should just produce the symbol in the output
+// and not produce a reference to a label with an empty name.
+@
+
+--- ref-function-empty-label ---
+// using ref() should also not be possible
+// Error: 6-7 unexpected less-than operator
+// Error: 7-8 unexpected greater-than operator
+#ref(<>)

tests/suite/scripting/ops.typ

@@ -264,6 +264,8 @@
 #test("Hey" not in "abheyCd", true)
 #test("a" not
 /* fun comment? */ in "abc", false)
+#test("sys" in std, true)
+#test("system" in std, false)
 
 --- ops-not-trailing ---
 // Error: 10 expected keyword `in`

tests/suite/syntax/numbers.typ

@@ -2,6 +2,7 @@
 
 --- numbers ---
 // Test numbers in text mode.
+#set text(font: ("Libertinus Serif", "Noto Sans Arabic"))
 12 \
 12.0 \
 3.14 \

tests/suite/text/deco.typ

@@ -83,3 +83,11 @@ We can also specify a customized value
 #highlight(stroke: 2pt + blue)[abc]
 #highlight(stroke: (top: blue, left: red, bottom: green, right: orange))[abc]
 #highlight(stroke: 1pt, radius: 3pt)[#lorem(5)]
+
+--- html-deco html ---
+#strike[Struck]
+#highlight[Highlighted]
+#underline[Underlined]
+#overline[Overlined]
+
+#(strike, highlight, underline, overline).fold([Mixed], (it, f) => f(it))

tests/suite/visualize/gradient.typ

@@ -666,3 +666,29 @@ $ A = mat(
 #let _ = gradient.linear(..my-gradient.stops())
 #let my-gradient2 = gradient.linear(red, blue).repeat(5, mirror: true)
 #let _ = gradient.linear(..my-gradient2.stops())
+
+--- issue-6162-coincident-gradient-stops-export-png ---
+// Ensure that multiple gradient stops with the same position
+// don't cause a panic.
+#rect(
+  fill: gradient.linear(
+    (red, 0%),
+    (green, 0%),
+    (blue, 100%),
+  )
+)
+#rect(
+  fill: gradient.linear(
+    (red, 0%),
+    (green, 100%),
+    (blue, 100%),
+  )
+)
+#rect(
+  fill: gradient.linear(
+    (white, 0%),
+    (red, 50%),
+    (green, 50%),
+    (blue, 100%),
+  )
+)