A11y empty xpath fix (#458)

* js function declared as string

* fixed a11y missing roles, improved xpath gen for text nodes

* added changeset

Author: miguelg719

Diff for: .changeset/gentle-pans-mix.md

@@ -0,0 +1,5 @@
+---
+"@browserbasehq/stagehand": patch
+---
+
+Updated getAccessibilityTree() to make sure it doesn't skip useful nodes. Improved getXPathByResolvedObjectId() to account for text nodes and not skip generation

Diff for: lib/a11y/utils.ts

@@ -33,6 +33,11 @@ export function formatSimplifiedTree(
 function cleanStructuralNodes(
   node: AccessibilityNode,
 ): AccessibilityNode | null {
+  // Filter out nodes with negative IDs
+  if (node.nodeId && parseInt(node.nodeId) < 0) {
+    return null;
+  }
+
   // Base case: leaf node
   if (!node.children) {
     return node.role === "generic" || node.role === "none" ? null : node;
@@ -181,33 +186,54 @@ export async function getAccessibilityTree(
 
 // This function is wrapped into a string and sent as a CDP command
 // It is not meant to be actually executed here
-const functionString = `function getNodePath(el) {
-  if (!el || el.nodeType !== Node.ELEMENT_NODE) return "";
-  const pathSegments = [];
+const functionString = `
+function getNodePath(el) {
+  if (!el || (el.nodeType !== Node.ELEMENT_NODE && el.nodeType !== Node.TEXT_NODE)) {
+    console.log("el is not a valid node type");
+    return "";
+  }
+
+  const parts = [];
   let current = el;
-  while (current && current.nodeType === Node.ELEMENT_NODE) {
-    const tagName = current.nodeName.toLowerCase();
-    let index = 1;
-    let sibling = current.previousSibling;
-    while (sibling) {
+
+  while (current && (current.nodeType === Node.ELEMENT_NODE || current.nodeType === Node.TEXT_NODE)) {
+    let index = 0;
+    let hasSameTypeSiblings = false;
+    const siblings = current.parentElement
+      ? Array.from(current.parentElement.childNodes)
+      : [];
+
+    for (let i = 0; i < siblings.length; i++) {
+      const sibling = siblings[i];
       if (
-        sibling.nodeType === Node.ELEMENT_NODE &&
-        sibling.nodeName.toLowerCase() === tagName
+        sibling.nodeType === current.nodeType &&
+        sibling.nodeName === current.nodeName
       ) {
-        index++;
+        index = index + 1;
+        hasSameTypeSiblings = true;
+        if (sibling.isSameNode(current)) {
+          break;
+        }
       }
-      sibling = sibling.previousSibling;
     }
-    const segment = index > 1 ? tagName + "[" + index + "]" : tagName;
-    pathSegments.unshift(segment);
-    current = current.parentNode;
+
     if (!current || !current.parentNode) break;
-    if (current.nodeName.toLowerCase() === "html") {
-      pathSegments.unshift("html");
+    if (current.nodeName.toLowerCase() === "html"){
+      parts.unshift("html");
       break;
     }
+
+    // text nodes are handled differently in XPath
+    if (current.nodeName !== "#text") {
+      const tagName = current.nodeName.toLowerCase();
+      const pathIndex = hasSameTypeSiblings ? \`[\${index}]\` : "";
+      parts.unshift(\`\${tagName}\${pathIndex}\`);
+    }
+    
+    current = current.parentElement;
   }
-  return "/" + pathSegments.join("/");
+
+  return parts.length ? \`/\${parts.join("/")}\` : "";
 }`;
 
 export async function getXPathByResolvedObjectId(

Diff for: lib/handlers/observeHandler.ts

@@ -114,15 +114,46 @@ export class StagehandObserveHandler {
 
         if (useAccessibilityTree) {
           // Generate xpath for the given element if not found in selectorMap
+          this.logger({
+            category: "observation",
+            message: "Getting xpath for element",
+            level: 1,
+            auxiliary: {
+              elementId: {
+                value: elementId.toString(),
+                type: "string",
+              },
+            },
+          });
+
+          const args = { backendNodeId: elementId };
           const { object } = await this.stagehandPage.sendCDP<{
             object: { objectId: string };
-          }>("DOM.resolveNode", {
-            backendNodeId: elementId,
-          });
+          }>("DOM.resolveNode", args);
+
+          if (!object || !object.objectId) {
+            this.logger({
+              category: "observation",
+              message: `Invalid object ID returned for element: ${elementId}`,
+              level: 1,
+            });
+            return null;
+          }
+
           const xpath = await getXPathByResolvedObjectId(
             await this.stagehandPage.getCDPClient(),
             object.objectId,
           );
+
+          if (!xpath || xpath === "") {
+            this.logger({
+              category: "observation",
+              message: `Empty xpath returned for element: ${elementId}`,
+              level: 1,
+            });
+            return null;
+          }
+
           return {
             ...rest,
             selector: `xpath=${xpath}`,