Add focusable map to preserve semantic elements

packages/core/lib/v3/types/private/snapshot.ts

@@ -48,6 +48,7 @@ export type SessionDomIndex = {
   absByBe: Map<number, string>;
   tagByBe: Map<number, string>;
   scrollByBe: Map<number, boolean>;
+  focusableByBe: Map<number, boolean>;
   docRootOf: Map<number, number>;
   contentDocRootByIframe: Map<number, number>;
 };
@@ -56,6 +57,7 @@ export type FrameDomMaps = {
   tagNameMap: Record<string, string>;
   xpathMap: Record<string, string>;
   scrollableMap: Record<string, boolean>;
+  focusableMap: Record<string, boolean>;
   urlMap: Record<string, string>;
 };
 
@@ -103,6 +105,7 @@ export type A11yOptions = {
   experimental: boolean;
   tagNameMap: Record<string, string>;
   scrollableMap: Record<string, boolean>;
+  focusableMap: Record<string, boolean>;
   encode: (backendNodeId: number) => string;
 };
 

packages/core/lib/v3/understudy/a11y/snapshot/a11yTree.ts

@@ -151,10 +151,15 @@ export async function buildHierarchicalTree(
   const nodeMap = new Map<string, A11yNode>();
 
   for (const n of nodes) {
+    const isFocusable = n.encodedId
+      ? opts.focusableMap[n.encodedId] === true
+      : false;
+
     const keep =
       !!(n.name && n.name.trim()) ||
       !!(n.childIds && n.childIds.length) ||
-      !isStructural(n.role);
+      !isStructural(n.role) ||
+      isFocusable;
     if (!keep) continue;
     nodeMap.set(n.nodeId, { ...n });
   }
@@ -179,8 +184,20 @@ export async function buildHierarchicalTree(
   async function pruneStructuralSafe(node: A11yNode): Promise<A11yNode | null> {
     if (+node.nodeId < 0) return null;
 
+    const isFocusable = node.encodedId
+      ? opts.focusableMap[node.encodedId] === true
+      : false;
+
     const children = node.children ?? [];
     if (!children.length) {
+      if (isFocusable) {
+        let newRole = node.role;
+        if ((newRole === "generic" || newRole === "none") && node.encodedId) {
+          const tagName = opts.tagNameMap[node.encodedId];
+          if (tagName) newRole = tagName;
+        }
+        return { ...node, role: newRole };
+      }
       return isStructural(node.role) ? null : node;
     }
 
@@ -190,7 +207,7 @@ export async function buildHierarchicalTree(
 
     const prunedStatic = removeRedundantStaticTextChildren(node, cleanedKids);
 
-    if (isStructural(node.role)) {
+    if (isStructural(node.role) && !isFocusable) {
       if (prunedStatic.length === 1) return prunedStatic[0]!;
       if (prunedStatic.length === 0) return null;
     }

packages/core/lib/v3/understudy/a11y/snapshot/capture.ts

@@ -168,13 +168,14 @@ export async function tryScopedSnapshot(
     const sameSessionAsParent =
       !!parentId &&
       ownerSession(page, parentId) === ownerSession(page, targetFrameId);
-    const { tagNameMap, xpathMap, scrollableMap } = await domMapsForSession(
-      owningSess,
-      targetFrameId,
-      pierce,
-      (fid, be) => `${page.getOrdinal(fid)}-${be}`,
-      sameSessionAsParent,
-    );
+    const { tagNameMap, xpathMap, scrollableMap, focusableMap } =
+      await domMapsForSession(
+        owningSess,
+        targetFrameId,
+        pierce,
+        (fid, be) => `${page.getOrdinal(fid)}-${be}`,
+        sameSessionAsParent,
+      );
 
     const { outline, urlMap, scopeApplied } = await a11yForFrame(
       owningSess,
@@ -184,6 +185,7 @@ export async function tryScopedSnapshot(
         tagNameMap,
         experimental: options?.experimental ?? false,
         scrollableMap,
+        focusableMap,
         encode: (backendNodeId) =>
           `${page.getOrdinal(targetFrameId)}-${backendNodeId}`,
       },
@@ -304,6 +306,7 @@ async function collectPerFrameMaps(
     const tagNameMap: Record<string, string> = {};
     const xpathMap: Record<string, string> = {};
     const scrollableMap: Record<string, boolean> = {};
+    const focusableMap: Record<string, boolean> = {};
     const enc = (be: number) => `${page.getOrdinal(frameId)}-${be}`;
     const baseAbs = idx.absByBe.get(docRootBe) ?? "/";
 
@@ -318,17 +321,25 @@ async function collectPerFrameMaps(
       const tag = idx.tagByBe.get(be);
       if (tag) tagNameMap[key] = tag;
       if (idx.scrollByBe.get(be)) scrollableMap[key] = true;
+      if (idx.focusableByBe.get(be)) focusableMap[key] = true;
     }
 
     const { outline, urlMap } = await a11yForFrame(sess, frameId, {
       experimental: options?.experimental ?? false,
       tagNameMap,
       scrollableMap,
+      focusableMap,
       encode: (backendNodeId) => `${page.getOrdinal(frameId)}-${backendNodeId}`,
     });
 
     perFrameOutlines.push({ frameId, outline });
-    perFrameMaps.set(frameId, { tagNameMap, xpathMap, scrollableMap, urlMap });
+    perFrameMaps.set(frameId, {
+      tagNameMap,
+      xpathMap,
+      scrollableMap,
+      focusableMap,
+      urlMap,
+    });
   }
 
   return { perFrameMaps, perFrameOutlines };

packages/core/lib/v3/understudy/a11y/snapshot/domTree.ts

@@ -8,6 +8,31 @@ import {
   normalizeXPath,
 } from "./xpathUtils";
 
+const NATIVE_FOCUSABLE_TAGS = new Set([
+  "a",
+  "button",
+  "input",
+  "select",
+  "textarea",
+  "details",
+  "summary",
+]);
+
+/** Check if a DOM node is focusable via tag or tabindex >= 0. */
+export function isNodeFocusable(node: Protocol.DOM.Node): boolean {
+  const tag = String(node.nodeName ?? "").toLowerCase();
+  if (NATIVE_FOCUSABLE_TAGS.has(tag)) return true;
+
+  const attrs = node.attributes ?? [];
+  for (let i = 0; i < attrs.length; i += 2) {
+    if (attrs[i]?.toLowerCase() === "tabindex") {
+      const val = parseInt(attrs[i + 1] ?? "", 10);
+      if (!isNaN(val) && val >= 0) return true;
+    }
+  }
+  return false;
+}
+
 // starting from infinite depth (-1), exponentially shrink down to 1
 const DOM_DEPTH_ATTEMPTS = [-1, 256, 128, 64, 32, 16, 8, 4, 2, 1];
 const DESCRIBE_DEPTH_ATTEMPTS = [-1, 64, 32, 16, 8, 4, 2, 1];
@@ -184,6 +209,7 @@ export async function domMapsForSession(
   tagNameMap: Record<string, string>;
   xpathMap: Record<string, string>;
   scrollableMap: Record<string, boolean>;
+  focusableMap: Record<string, boolean>;
 }> {
   await session.send("DOM.enable").catch(() => {});
   const root = await getDomTreeWithFallback(session, pierce);
@@ -210,6 +236,7 @@ export async function domMapsForSession(
   const tagNameMap: Record<string, string> = {};
   const xpathMap: Record<string, string> = {};
   const scrollableMap: Record<string, boolean> = {};
+  const focusableMap: Record<string, boolean> = {};
 
   type StackEntry = { node: Protocol.DOM.Node; xpath: string };
   const stack: StackEntry[] = [{ node: startNode, xpath: "" }];
@@ -223,6 +250,7 @@ export async function domMapsForSession(
       xpathMap[encId] = xpath || "/";
       const isScrollable = node?.isScrollable === true;
       if (isScrollable) scrollableMap[encId] = true;
+      if (isNodeFocusable(node)) focusableMap[encId] = true;
     }
 
     const kids = node.children ?? [];
@@ -246,7 +274,7 @@ export async function domMapsForSession(
     }
   }
 
-  return { tagNameMap, xpathMap, scrollableMap };
+  return { tagNameMap, xpathMap, scrollableMap, focusableMap };
 }
 
 /**
@@ -264,6 +292,7 @@ export async function buildSessionDomIndex(
   const absByBe = new Map<number, string>();
   const tagByBe = new Map<number, string>();
   const scrollByBe = new Map<number, boolean>();
+  const focusableByBe = new Map<number, boolean>();
   const docRootOf = new Map<number, number>();
   const contentDocRootByIframe = new Map<number, number>();
 
@@ -277,6 +306,7 @@ export async function buildSessionDomIndex(
       absByBe.set(node.backendNodeId, xp || "/");
       tagByBe.set(node.backendNodeId, String(node.nodeName).toLowerCase());
       if (node?.isScrollable === true) scrollByBe.set(node.backendNodeId, true);
+      if (isNodeFocusable(node)) focusableByBe.set(node.backendNodeId, true);
       docRootOf.set(node.backendNodeId, docRootBe);
     }
 
@@ -306,6 +336,7 @@ export async function buildSessionDomIndex(
     absByBe,
     tagByBe,
     scrollByBe,
+    focusableByBe,
     docRootOf,
     contentDocRootByIframe,
   };

packages/core/tests/snapshot-a11y-resolvers.test.ts

@@ -61,6 +61,7 @@ describe("a11yForFrame", () => {
       experimental: false,
       tagNameMap: { "enc-100": "#document", "enc-101": "a" },
       scrollableMap: {},
+      focusableMap: {},
       encode: (backend) => `enc-${backend}`,
     };
 
@@ -113,6 +114,7 @@ describe("a11yForFrame", () => {
       experimental: false,
       tagNameMap: { "enc-101": "a" },
       scrollableMap: {},
+      focusableMap: {},
       encode: (backend) => `enc-${backend}`,
     };
 
@@ -137,6 +139,7 @@ describe("a11yForFrame", () => {
       experimental: false,
       tagNameMap: {},
       scrollableMap: {},
+      focusableMap: {},
       encode: (backend) => `enc-${backend}`,
     };
 
@@ -288,6 +291,7 @@ describe("tryScopedSnapshot", () => {
         tagNameMap: { "1-10": "div" },
         xpathMap: { "1-10": "/div[1]" },
         scrollableMap: {},
+        focusableMap: {},
       });
     const a11ySpy = vi.spyOn(a11yTree, "a11yForFrame").mockResolvedValue({
       outline: "[1-10] div",
@@ -321,6 +325,7 @@ describe("tryScopedSnapshot", () => {
       tagNameMap: { "1-10": "div" },
       xpathMap: { "1-10": "/div[1]" },
       scrollableMap: {},
+      focusableMap: {},
     });
     vi.spyOn(a11yTree, "a11yForFrame").mockResolvedValue({
       outline: "ignored",
@@ -356,6 +361,7 @@ describe("tryScopedSnapshot", () => {
       tagNameMap: { "1-10": "div" },
       xpathMap: { "1-10": "/div[1]" },
       scrollableMap: {},
+      focusableMap: {},
     });
     vi.spyOn(a11yTree, "a11yForFrame").mockResolvedValue({
       outline: "[1-10] div",

packages/core/tests/snapshot-a11y-tree-utils.test.ts

@@ -19,6 +19,7 @@ const defaultOpts: A11yOptions = {
   experimental: false,
   tagNameMap: {},
   scrollableMap: {},
+  focusableMap: {},
   encode: (backendNodeId: number) => `enc-${backendNodeId}`,
 };
 

packages/core/tests/snapshot-frame-merge.test.ts

@@ -31,6 +31,7 @@ describe("computeFramePrefixes", () => {
         {
           tagNameMap: {},
           scrollableMap: {},
+          focusableMap: {},
           urlMap: {},
           xpathMap: { "0-200": "/html[1]/body[1]/iframe[1]" },
         },
@@ -78,6 +79,7 @@ describe("computeFramePrefixes", () => {
         {
           tagNameMap: {},
           scrollableMap: {},
+          focusableMap: {},
           urlMap: {},
           xpathMap: { "0-200": "/iframe[1]" },
         },
@@ -87,6 +89,7 @@ describe("computeFramePrefixes", () => {
         {
           tagNameMap: {},
           scrollableMap: {},
+          focusableMap: {},
           urlMap: {},
           xpathMap: { "1-300": "/div[1]/iframe[1]" },
         },
@@ -125,6 +128,7 @@ describe("computeFramePrefixes", () => {
         {
           tagNameMap: {},
           scrollableMap: {},
+          focusableMap: {},
           urlMap: {},
           xpathMap: {},
         },
@@ -166,6 +170,7 @@ describe("mergeFramesIntoSnapshot", () => {
         {
           tagNameMap: {},
           scrollableMap: {},
+          focusableMap: {},
           urlMap: { "0-10": "https://example.com" },
           xpathMap: { "0-10": "/html[1]/body[1]" },
         },
@@ -175,6 +180,7 @@ describe("mergeFramesIntoSnapshot", () => {
         {
           tagNameMap: {},
           scrollableMap: {},
+          focusableMap: {},
           urlMap: { "1-20": "https://child.com" },
           xpathMap: { "1-20": "/div[1]/span[1]" },
         },
@@ -226,6 +232,7 @@ describe("mergeFramesIntoSnapshot", () => {
         {
           tagNameMap: {},
           scrollableMap: {},
+          focusableMap: {},
           urlMap: {},
           xpathMap: { "0-10": "/html[1]" },
         },
@@ -270,6 +277,7 @@ describe("mergeFramesIntoSnapshot", () => {
         {
           tagNameMap: {},
           scrollableMap: {},
+          focusableMap: {},
           urlMap: {},
           xpathMap: {},
         },
@@ -308,6 +316,7 @@ describe("mergeFramesIntoSnapshot", () => {
         {
           tagNameMap: {},
           scrollableMap: {},
+          focusableMap: {},
           urlMap: {},
           xpathMap: {},
         },