fix(dom): complete tabIndex defaults

moli-renderer-v8/src/native_bridge/document.rs

@@ -304,6 +304,7 @@ pub(in crate::native_bridge::document) use structure::set_document_body_for_nati
 pub(crate) const XHTML_NS: &str = "http://www.w3.org/1999/xhtml";
 pub(crate) const SVG_NS: &str = "http://www.w3.org/2000/svg";
 pub(crate) const XLINK_NS: &str = "http://www.w3.org/1999/xlink";
+pub(crate) const MATHML_NS: &str = "http://www.w3.org/1998/Math/MathML";
 
 #[derive(Clone, Copy)]
 #[repr(u32)]

moli-renderer-v8/src/native_bridge/element/focus.rs

@@ -73,6 +73,58 @@ fn contenteditable_state_from_attr(value: &str) -> Option<bool> {
     }
 }
 
+fn html_area_has_associated_image_map(runtime: &JsContextHost, handle: DomHandle) -> bool {
+    let dom = runtime.dom_host();
+    let Some(area) = dom.node(handle).and_then(Node::as_element) else {
+        return false;
+    };
+    if area.namespace() != document::XHTML_NS
+        || area.local_name() != "area"
+        || !area.has_attribute("href")
+    {
+        return false;
+    }
+
+    let mut ancestor = dom.parent_node(handle);
+    let map_name = loop {
+        let Some(candidate) = ancestor else {
+            return false;
+        };
+        let Some(element) = dom.node(candidate).and_then(Node::as_element) else {
+            ancestor = dom.parent_node(candidate);
+            continue;
+        };
+        if element.namespace() == document::XHTML_NS && element.local_name() == "map" {
+            let Some(name) = element.attribute("name").filter(|name| !name.is_empty()) else {
+                return false;
+            };
+            break name.to_owned();
+        }
+        ancestor = dom.parent_node(candidate);
+    };
+
+    let mut stack = dom
+        .child_handles(runtime.document_handle())
+        .collect::<Vec<_>>();
+    while let Some(candidate) = stack.pop() {
+        let Some(element) = dom.node(candidate).and_then(Node::as_element) else {
+            stack.extend(dom.child_handles(candidate));
+            continue;
+        };
+        if element.namespace() == document::XHTML_NS
+            && matches!(element.local_name(), "img" | "object")
+            && element
+                .attribute("usemap")
+                .and_then(|value| value.strip_prefix('#'))
+                .is_some_and(|name| name == map_name)
+        {
+            return true;
+        }
+        stack.extend(dom.child_handles(candidate));
+    }
+    false
+}
+
 pub(super) fn is_focusable(runtime: &JsContextHost, handle: DomHandle) -> bool {
     let Some(element) = runtime.dom_host().node(handle).and_then(Node::as_element) else {
         return false;
@@ -85,6 +137,9 @@ pub(super) fn is_focusable(runtime: &JsContextHost, handle: DomHandle) -> bool {
     {
         return false;
     }
+    if element.namespace() == document::XHTML_NS && element.local_name() == "area" {
+        return html_area_has_associated_image_map(runtime, handle);
+    }
     matches!(
         element.local_name(),
         "body" | "input" | "button" | "select" | "textarea" | "a" | "iframe" | "frame"

moli-renderer-v8/src/native_bridge/element/global_attributes.rs

@@ -6,6 +6,7 @@ use crate::webidl;
 
 use super::super::{
     JsContextHost,
+    document::{MATHML_NS, SVG_NS, XHTML_NS},
     node::{
         node_is_element, node_runtime_and_handle_from_object_or_detached,
         throw_incompatible_getter_receiver, throw_incompatible_setter_receiver,
@@ -13,6 +14,7 @@ use super::super::{
     throw_dom_exception,
 };
 
+use super::details_dialog::main_summary_child;
 use super::reflection::{
     DomStringReflection, ElementReflectionInterface, NullToEmptyDomStringReflection,
     UnsignedLongReflection, UsvStringReflection, remove_reflected_attribute,
@@ -2588,11 +2590,21 @@ fn default_tab_index_for(runtime: &JsContextHost, handle: DomHandle) -> i32 {
     let Some(element) = runtime.dom_host().node(handle).and_then(Node::as_element) else {
         return -1;
     };
-    if element.namespace() != "http://www.w3.org/1999/xhtml" {
-        return -1;
-    }
-    match element.local_name() {
-        "a" | "button" | "input" | "select" | "textarea" => 0,
+    match (element.namespace(), element.local_name()) {
+        (
+            XHTML_NS,
+            "a" | "area" | "button" | "frame" | "iframe" | "input" | "object" | "select"
+            | "textarea",
+        )
+        | (SVG_NS | MATHML_NS, "a") => 0,
+        (XHTML_NS, "summary")
+            if runtime
+                .dom_host()
+                .parent_node(handle)
+                .is_some_and(|parent| main_summary_child(runtime, parent) == Some(handle)) =>
+        {
+            0
+        }
         _ => -1,
     }
 }

moli-renderer-v8/src/script_vm/tests/dom_elements/focus.rs

@@ -1,5 +1,58 @@
 use super::*;
 
+#[test]
+fn image_map_area_focusability_supports_autofocus() {
+    let mut vm = new_storage_test_vm("https://area-autofocus.test/");
+
+    let setup = vm
+        .eval(
+            r##"
+(() => {
+  const root = document.documentElement ||
+    document.appendChild(document.createElement('html'));
+  const body = document.body || root.appendChild(document.createElement('body'));
+  body.innerHTML = `
+    <area id="outside" href="#" autofocus>
+    <map name="unused"><area id="unreferenced" href="#" autofocus></map>
+    <map name="active">
+      <area id="no-href" autofocus>
+      <area id="target" href="#" autofocus>
+    </map>
+    <img usemap="#active">`;
+
+  const rejected = ['outside', 'unreferenced', 'no-href'].map(id => {
+    const candidate = document.getElementById(id);
+    candidate.focus();
+    return document.activeElement !== candidate;
+  });
+  return rejected.every(Boolean) && document.activeElement === body;
+})()
+"##,
+        )
+        .expect("image-map focusability fixture should initialize");
+    assert_eq!(setup, "true");
+
+    vm.with_default_context_scope_and_checkpoint_for_test(|scope, runtime_ptr| {
+        assert!(
+            crate::native_bridge::element::post_parse_autofocus_is_pending(unsafe {
+                &*runtime_ptr
+            })
+        );
+        assert!(crate::native_bridge::element::process_post_parse_autofocus(
+            scope,
+            runtime_ptr
+        ));
+        Ok(())
+    })
+    .expect("image-map area autofocus should run");
+
+    assert_eq!(
+        vm.eval("document.activeElement === document.getElementById('target')")
+            .expect("image-map autofocus result should remain observable"),
+        "true"
+    );
+}
+
 #[test]
 fn focus_prevent_scroll_controls_real_nested_scroll_container_reveal() {
     let mut vm = new_storage_test_vm("https://focus-prevent-scroll.test/");

moli-renderer-v8/src/script_vm/tests/dom_elements/live_document.rs

@@ -1045,6 +1045,85 @@ fn htmlelement_standard_accessors_live_on_owner_prototypes() {
     assert_eq!(result, "ok");
 }
 
+#[test]
+fn tab_index_getter_uses_the_spec_default_element_set() {
+    let mut vm = new_parsed_test_vm(
+        "https://tab-index-defaults.test/",
+        "<!doctype html><html><head></head><body></body></html>",
+    );
+
+    let result = vm
+        .eval(
+            r#"
+            (() => {
+              const assert = (condition, message) => {
+                if (!condition) throw new Error(message);
+              };
+              const svg = "http://www.w3.org/2000/svg";
+              const mathml = "http://www.w3.org/1998/Math/MathML";
+              const other = "https://tab-index-defaults.test/namespace";
+              const exercise = ownerDocument => {
+                for (const name of [
+                  "a", "area", "button", "frame", "iframe", "input", "object", "select", "textarea"
+                ]) {
+                  const element = ownerDocument.createElement(name);
+                  assert(element.tabIndex === 0, `${name} default`);
+                }
+
+                const div = ownerDocument.createElement("div");
+                assert(div.tabIndex === -1, "ordinary HTML element default");
+
+                const svgAnchor = ownerDocument.createElementNS(svg, "a");
+                const svgGroup = ownerDocument.createElementNS(svg, "g");
+                const mathAnchor = ownerDocument.createElementNS(mathml, "a");
+                const mathRow = ownerDocument.createElementNS(mathml, "mrow");
+                const foreignAnchor = ownerDocument.createElementNS(other, "a");
+                assert(svgAnchor.tabIndex === 0, "SVG a default");
+                assert(svgGroup.tabIndex === -1, "other SVG element default");
+                assert(mathAnchor.tabIndex === 0, "MathML a default");
+                assert(mathRow.tabIndex === -1, "other MathML element default");
+                assert(foreignAnchor.tabIndex === undefined, "unrelated namespace has no mixin");
+
+                const details = ownerDocument.createElement("details");
+                const nonSummary = ownerDocument.createElement("span");
+                const firstSummary = ownerDocument.createElement("summary");
+                const secondSummary = ownerDocument.createElement("summary");
+                details.append(nonSummary, firstSummary, secondSummary);
+                assert(firstSummary.tabIndex === 0, "first summary child default");
+                assert(secondSummary.tabIndex === -1, "later summary child default");
+                assert(ownerDocument.createElement("summary").tabIndex === -1,
+                  "orphan summary default");
+
+                firstSummary.remove();
+                assert(secondSummary.tabIndex === 0, "summary default follows tree mutation");
+                details.append(firstSummary);
+                assert(secondSummary.tabIndex === 0 && firstSummary.tabIndex === -1,
+                  "first summary is based on current child order");
+
+                const wrapper = ownerDocument.createElement("div");
+                const nestedSummary = ownerDocument.createElement("summary");
+                wrapper.append(nestedSummary);
+                details.prepend(wrapper);
+                assert(nestedSummary.tabIndex === -1, "nested summary is not a details summary");
+
+                secondSummary.setAttribute("tabindex", "-7");
+                assert(secondSummary.tabIndex === -7, "explicit valid tabindex wins");
+                secondSummary.setAttribute("tabindex", "invalid");
+                assert(secondSummary.tabIndex === 0, "invalid tabindex uses element default");
+                div.setAttribute("tabindex", "invalid");
+                assert(div.tabIndex === -1, "invalid tabindex uses ordinary default");
+              };
+
+              exercise(document);
+              return "ok";
+            })()
+            "#,
+        )
+        .expect("tabIndex default getter behavior should evaluate");
+
+    assert_eq!(result, "ok");
+}
+
 #[test]
 fn inner_and_outer_text_setters_build_rendered_fragments_and_merge_text_endpoints() {
     let mut vm = new_parsed_test_vm(