fix(extension): support iframe content in VOM observations

apps/extension/src/tools/vom/frame-capture.ts

@@ -0,0 +1,75 @@
+import type { CdpRunner } from "../shared";
+import type { CapturedViewModel } from "./capture";
+import {
+  buildFrameDocuments,
+  type FrameAxBatch,
+  type FrameDocument,
+  type FrameOwnedAxNode,
+} from "./frame-document";
+
+export type FrameAxNode = FrameOwnedAxNode;
+export type CapturedFrameDocument<T extends FrameAxNode> = FrameDocument<T>;
+
+function throwIfAborted(signal?: AbortSignal): void {
+  if (signal?.aborted) throw new DOMException("observation aborted", "AbortError");
+}
+
+function isAbortError(err: unknown): boolean {
+  return err instanceof Error && err.name === "AbortError";
+}
+
+function capturedFrameIds(captured: CapturedViewModel): string[] {
+  const frameIds = new Set<string>();
+  if (captured.rootFrameId) frameIds.add(captured.rootFrameId);
+  for (const frameId of captured.frameNodes?.keys() ?? []) frameIds.add(frameId);
+  if (frameIds.size === 0) frameIds.add("root");
+  return [...frameIds];
+}
+
+async function captureAxTrees<T extends FrameAxNode>(
+  cdp: CdpRunner,
+  tabId: number,
+  captured: CapturedViewModel,
+  signal?: AbortSignal,
+): Promise<FrameAxBatch<T>[]> {
+  const frameIds = capturedFrameIds(captured);
+  let firstFailure: unknown;
+  await cdp.send(tabId, "Accessibility.enable", {});
+  const trees = await Promise.all(
+    frameIds.map(async (frameId): Promise<FrameAxBatch<T>> => {
+      try {
+        throwIfAborted(signal);
+        const result = await cdp.send<{ nodes?: T[] }>(
+          tabId,
+          "Accessibility.getFullAXTree",
+          frameId === "root" ? {} : { frameId },
+        );
+        throwIfAborted(signal);
+        return { frameId, nodes: result.nodes ?? [] };
+      } catch (err) {
+        if (isAbortError(err)) throw err;
+        firstFailure ??= err;
+        console.debug("[bsk observation] frame AX capture failed", { frameId, err });
+        return { frameId, nodes: [] };
+      }
+    }),
+  );
+  const capturedNodeCount = [...captured.iframeNodes.values()].reduce(
+    (count, nodes) => count + nodes.length,
+    captured.nodes.length,
+  );
+  if (firstFailure && capturedNodeCount === 0 && trees.every((tree) => tree.nodes.length === 0)) {
+    throw firstFailure;
+  }
+  return trees;
+}
+
+export async function captureFrameData<T extends FrameAxNode>(
+  cdp: CdpRunner,
+  tabId: number,
+  captured: CapturedViewModel,
+  signal?: AbortSignal,
+): Promise<CapturedFrameDocument<T>[]> {
+  const batches = await captureAxTrees<T>(cdp, tabId, captured, signal);
+  return buildFrameDocuments(batches, captured);
+}