feat(vom): fixture test

fix(recording): support user action recording in iframes and OOPIFs

apps/extension/src/content/__tests__/record-capture.test.ts

@@ -1,6 +1,6 @@
 import { beforeEach, describe, expect, it, vi } from "vitest";
-import { RECORD_START, RECORD_STOP, type RecordStepPayload } from "@/lib/record-bridge";
-import { handleRecordContentMessage, startRecordCapture } from "../record-capture";
+import type { RecordStepPayload } from "@/lib/record-bridge";
+import { startRecordCapture } from "../record-capture";
 
 vi.stubGlobal("chrome", {
   runtime: {
@@ -48,118 +48,6 @@ function click(el: Element): void {
   el.dispatchEvent(new MouseEvent("click", { bubbles: true, button: 0, detail: 1 }));
 }
 
-describe("handleRecordContentMessage stop/cancel", () => {
-  it("ignores STOP when no recording is active", () => {
-    const dispose = vi.fn();
-    const onStop = vi.fn();
-    const setActiveRequestId = vi.fn();
-    const setCapture = vi.fn();
-    const sendResponse = vi.fn();
-
-    const needsAsync = handleRecordContentMessage(
-      { type: RECORD_STOP, requestId: "rec-stale" },
-      {
-        activeRequestId: null,
-        capture: { dispose },
-        setActiveRequestId,
-        setCapture,
-        onStart: vi.fn(),
-        onStop,
-      },
-      sendResponse,
-    );
-
-    expect(needsAsync).toBe(false);
-    expect(dispose).not.toHaveBeenCalled();
-    expect(onStop).not.toHaveBeenCalled();
-    expect(setActiveRequestId).not.toHaveBeenCalled();
-    expect(setCapture).not.toHaveBeenCalled();
-    expect(sendResponse).not.toHaveBeenCalled();
-  });
-
-  it("ignores STOP for a mismatched requestId", () => {
-    const dispose = vi.fn();
-    const onStop = vi.fn();
-
-    const needsAsync = handleRecordContentMessage(
-      { type: RECORD_STOP, requestId: "rec-other" },
-      {
-        activeRequestId: "rec-1",
-        capture: { dispose },
-        setActiveRequestId: vi.fn(),
-        setCapture: vi.fn(),
-        onStart: vi.fn(),
-        onStop,
-      },
-      vi.fn(),
-    );
-
-    expect(needsAsync).toBe(false);
-    expect(dispose).not.toHaveBeenCalled();
-    expect(onStop).not.toHaveBeenCalled();
-  });
-
-  it("keeps a failed STOP retryable and redelivers its recorded step", async () => {
-    document.body.innerHTML = `<label for="retry">Draft</label><input id="retry" />`;
-    const sendMessage = vi.mocked(chrome.runtime.sendMessage);
-    sendMessage.mockReset();
-    sendMessage.mockRejectedValueOnce(new Error("service worker unavailable"));
-    sendMessage.mockRejectedValueOnce(new Error("service worker still unavailable"));
-    sendMessage.mockResolvedValueOnce({ ok: true, sequence: 1 });
-
-    let activeRequestId: string | null = null;
-    let capture: ReturnType<typeof startRecordCapture> | null = null;
-    const onStop = vi.fn();
-    const dispatch = (
-      message:
-        | { type: typeof RECORD_START; requestId: string; startedAtMs?: number }
-        | { type: typeof RECORD_STOP; requestId: string },
-      sendResponse?: (response: unknown) => void,
-    ) =>
-      handleRecordContentMessage(
-        message,
-        {
-          activeRequestId,
-          capture,
-          setActiveRequestId: (id) => {
-            activeRequestId = id;
-          },
-          setCapture: (next) => {
-            capture = next;
-          },
-          onStart: vi.fn(),
-          onStop,
-        },
-        sendResponse,
-      );
-
-    dispatch({ type: RECORD_START, requestId: "rec-retry" });
-    const input = document.querySelector("input")!;
-    input.dispatchEvent(new FocusEvent("focusin", { bubbles: true }));
-    input.value = "dirty final value";
-    input.dispatchEvent(new Event("input", { bubbles: true }));
-
-    const firstResponse = vi.fn();
-    expect(dispatch({ type: RECORD_STOP, requestId: "rec-retry" }, firstResponse)).toBe(true);
-    await vi.waitFor(() =>
-      expect(firstResponse).toHaveBeenCalledWith({
-        ok: false,
-        error: "failed to deliver one or more recorded steps",
-      }),
-    );
-    expect(activeRequestId).toBe("rec-retry");
-    expect(onStop).not.toHaveBeenCalled();
-
-    const retryResponse = vi.fn();
-    expect(dispatch({ type: RECORD_STOP, requestId: "rec-retry" }, retryResponse)).toBe(true);
-    await vi.waitFor(() => expect(retryResponse).toHaveBeenCalledWith({ ok: true }));
-
-    expect(sendMessage).toHaveBeenCalledTimes(3);
-    expect(activeRequestId).toBeNull();
-    expect(onStop).toHaveBeenCalledTimes(1);
-  });
-});
-
 describe("record-capture semantic", () => {
   let steps: RecordStepPayload[];
 
@@ -236,6 +124,19 @@ describe("record-capture semantic", () => {
     ]);
   });
 
+  it("does not emit page navigation from a child Document capture", () => {
+    const originalUrl = location.href;
+    const capture = startRecordCapture("rec-child", (step) => steps.push(step), {
+      captureNavigation: false,
+    });
+
+    history.pushState({}, "", "#inside-frame");
+    expect(steps).toEqual([]);
+
+    capture.dispose();
+    history.replaceState({}, "", originalUrl);
+  });
+
   it("does not record clicks on anonymous layout divs", () => {
     document.body.innerHTML = `
       <div id="chrome">page chrome</div>

apps/extension/src/content/__tests__/record-frame-agent.test.ts

@@ -0,0 +1,102 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+import type { RecordFramePortMessage } from "@/lib/recording/frame-bridge";
+import { RECORD_FRAME_START } from "@/lib/recording/frame-bridge";
+import { RECORD_DOCUMENT_ATTRIBUTE } from "@/shared/recording-document-identity";
+import { RecordFrameAgent } from "../recording/frame-agent";
+
+class PortListeners<T extends (...args: never[]) => unknown> {
+  readonly values = new Set<T>();
+  addListener = (listener: T) => this.values.add(listener);
+  removeListener = (listener: T) => this.values.delete(listener);
+}
+
+function portHarness() {
+  const onMessage = new PortListeners<(message: unknown) => void>();
+  const onDisconnect = new PortListeners<() => void>();
+  const outbound: RecordFramePortMessage[] = [];
+  const port = {
+    name: "bsk-record-frame",
+    onMessage,
+    onDisconnect,
+    postMessage(message: RecordFramePortMessage) {
+      outbound.push(message);
+      if (message.type === "ready") {
+        queueMicrotask(() => {
+          for (const listener of onMessage.values) {
+            listener({
+              type: "ready_ack",
+              requestId: message.requestId,
+              producerId: message.producerId,
+            });
+          }
+        });
+      }
+    },
+    disconnect: vi.fn(),
+  } as unknown as chrome.runtime.Port;
+  return {
+    port,
+    outbound,
+    receive(message: RecordFramePortMessage) {
+      for (const listener of onMessage.values) listener(message);
+    },
+  };
+}
+
+describe("RecordFrameAgent", () => {
+  afterEach(() => {
+    document.documentElement.removeAttribute(RECORD_DOCUMENT_ATTRIBUTE);
+    document.body.replaceChildren();
+  });
+
+  it("keeps a failed stop retryable and flushes the final dirty fill", async () => {
+    const harness = portHarness();
+    const sendMessage = vi
+      .fn<(message: { sequence: number }) => Promise<unknown>>()
+      .mockRejectedValueOnce(new Error("offline"))
+      .mockRejectedValueOnce(new Error("still offline"))
+      .mockImplementation(async (message) => ({ ok: true, sequence: message.sequence }));
+    vi.stubGlobal("chrome", {
+      runtime: {
+        connect: vi.fn(() => harness.port),
+        sendMessage,
+      },
+    });
+    document.body.innerHTML = `<label for="draft">Draft</label><input id="draft" />`;
+    const agent = new RecordFrameAgent();
+
+    await expect(
+      agent.start({ type: RECORD_FRAME_START, requestId: "rec-1", startedAtMs: 10 }),
+    ).resolves.toEqual({ ok: true });
+    expect(document.documentElement.hasAttribute(RECORD_DOCUMENT_ATTRIBUTE)).toBe(true);
+
+    const input = document.querySelector("input")!;
+    input.dispatchEvent(new FocusEvent("focusin", { bubbles: true }));
+    input.value = "final value";
+    input.dispatchEvent(new Event("input", { bubbles: true }));
+
+    harness.receive({ type: "stop", requestId: "rec-1", commandId: "stop-1" });
+    await vi.waitFor(() =>
+      expect(harness.outbound).toContainEqual({
+        type: "stopped",
+        requestId: "rec-1",
+        commandId: "stop-1",
+        ok: false,
+        error: "failed to deliver one or more recorded steps",
+      }),
+    );
+    expect(document.documentElement.hasAttribute(RECORD_DOCUMENT_ATTRIBUTE)).toBe(true);
+
+    harness.receive({ type: "stop", requestId: "rec-1", commandId: "stop-2" });
+    await vi.waitFor(() =>
+      expect(harness.outbound).toContainEqual({
+        type: "stopped",
+        requestId: "rec-1",
+        commandId: "stop-2",
+        ok: true,
+      }),
+    );
+    expect(sendMessage).toHaveBeenCalledTimes(3);
+    expect(document.documentElement.hasAttribute(RECORD_DOCUMENT_ATTRIBUTE)).toBe(false);
+  });
+});

apps/extension/src/content/record-capture.ts

@@ -12,21 +12,7 @@ import {
   hasDirectHoverInteractiveSignal,
   hasStrongHoverExpansionSignal,
 } from "@/lib/hover-trigger-policy";
-import {
-  isRecordCancelMessage,
-  isRecordStartMessage,
-  isRecordStopMessage,
-  RECORD_CANCEL,
-  RECORD_START,
-  RECORD_STEP,
-  RECORD_STOP,
-  type RecordCancelMessage,
-  type RecordStartAck,
-  type RecordStartMessage,
-  type RecordStepPayload,
-  type RecordStopAck,
-  type RecordStopMessage,
-} from "@/lib/record-bridge";
+import type { RecordStepPayload } from "@/lib/record-bridge";
 import { shouldRecordPress } from "@/lib/recording/draft-policy";
 import {
   closestHoverSurfaceCandidate,
@@ -36,18 +22,6 @@ import {
   isHoverSurfaceCandidateElement,
   isLikelyHoverSurfaceOwner,
 } from "./record-hover-surface";
-import { RecordStepDelivery } from "./record-step-delivery";
-
-const stepDeliveries = new Map<string, RecordStepDelivery>();
-const pendingStopFlushes = new Map<string, Promise<RecordStopAck>>();
-
-function deliveryFor(requestId: string): RecordStepDelivery {
-  const existing = stepDeliveries.get(requestId);
-  if (existing) return existing;
-  const created = new RecordStepDelivery(requestId);
-  stepDeliveries.set(requestId, created);
-  return created;
-}
 
 export interface RecordCaptureController {
   dispose(): void;
@@ -385,6 +359,7 @@ function scheduleInputCompletionCommit(
 export function startRecordCapture(
   _requestId: string,
   sendStep: (step: RecordStepPayload) => void,
+  options: { captureNavigation?: boolean } = {},
 ): RecordCaptureController {
   const emitStep = (step: RecordStepPayload) => {
     sendStep({ page_url: location.href, ...step });
@@ -921,26 +896,33 @@ export function startRecordCapture(
   document.addEventListener("change", onChange, true);
   document.addEventListener("keydown", onKeyDown, true);
 
-  const urlObserver = new MutationObserver(() => emitNavigateIfChanged());
-  urlObserver.observe(document, { subtree: true, childList: true });
+  const captureNavigation = options.captureNavigation ?? true;
+  const urlObserver = captureNavigation
+    ? new MutationObserver(() => emitNavigateIfChanged())
+    : null;
+  urlObserver?.observe(document, { subtree: true, childList: true });
   const onUrlEvent = () => emitNavigateIfChanged();
   // Wrap: passing commitFillSession directly would forward the DOM event as
   // the `commit` argument and stamp it onto the recorded fill step.
   const onPageHide = () => commitFillSession();
-  window.addEventListener("hashchange", onUrlEvent);
-  window.addEventListener("popstate", onUrlEvent);
+  if (captureNavigation) {
+    window.addEventListener("hashchange", onUrlEvent);
+    window.addEventListener("popstate", onUrlEvent);
+  }
   window.addEventListener("pagehide", onPageHide);
 
   const originalPushState = history.pushState;
   const originalReplaceState = history.replaceState;
-  history.pushState = function (...args: Parameters<History["pushState"]>) {
-    originalPushState.apply(this, args);
-    emitNavigateIfChanged(navigationActionPending ? true : undefined);
-  };
-  history.replaceState = function (...args: Parameters<History["replaceState"]>) {
-    originalReplaceState.apply(this, args);
-    emitNavigateIfChanged(navigationActionPending ? true : undefined);
-  };
+  if (captureNavigation) {
+    history.pushState = function (...args: Parameters<History["pushState"]>) {
+      originalPushState.apply(this, args);
+      emitNavigateIfChanged(navigationActionPending ? true : undefined);
+    };
+    history.replaceState = function (...args: Parameters<History["replaceState"]>) {
+      originalReplaceState.apply(this, args);
+      emitNavigateIfChanged(navigationActionPending ? true : undefined);
+    };
+  }
 
   return {
     dispose() {
@@ -954,99 +936,16 @@ export function startRecordCapture(
       document.removeEventListener("compositionend", onCompositionEnd, true);
       document.removeEventListener("change", onChange, true);
       document.removeEventListener("keydown", onKeyDown, true);
-      urlObserver.disconnect();
-      window.removeEventListener("hashchange", onUrlEvent);
-      window.removeEventListener("popstate", onUrlEvent);
+      urlObserver?.disconnect();
+      if (captureNavigation) {
+        window.removeEventListener("hashchange", onUrlEvent);
+        window.removeEventListener("popstate", onUrlEvent);
+      }
       window.removeEventListener("pagehide", onPageHide);
-      history.pushState = originalPushState;
-      history.replaceState = originalReplaceState;
+      if (captureNavigation) {
+        history.pushState = originalPushState;
+        history.replaceState = originalReplaceState;
+      }
     },
   };
 }
-
-export type RecordContentMessage = RecordStartMessage | RecordStopMessage | RecordCancelMessage;
-
-export function isRecordContentMessage(msg: unknown): msg is RecordContentMessage {
-  return isRecordStartMessage(msg) || isRecordStopMessage(msg) || isRecordCancelMessage(msg);
-}
-
-export function handleRecordContentMessage(
-  message: RecordContentMessage,
-  state: {
-    activeRequestId: string | null;
-    capture: RecordCaptureController | null;
-    setActiveRequestId(id: string | null): void;
-    setCapture(capture: RecordCaptureController | null): void;
-    onStart(requestId: string, startedAtMs?: number): void;
-    onStop(): void;
-  },
-  sendResponse?: (response: RecordStartAck | RecordStopAck) => void,
-): boolean {
-  if (isRecordStartMessage(message)) {
-    const delivery = deliveryFor(message.requestId);
-    state.capture?.dispose();
-    state.setCapture(
-      startRecordCapture(message.requestId, (step) => {
-        delivery.enqueue(step);
-      }),
-    );
-    state.setActiveRequestId(message.requestId);
-    state.onStart(message.requestId, message.startedAtMs);
-    sendResponse?.({ ok: true });
-    return sendResponse !== undefined;
-  }
-
-  if (isRecordStopMessage(message) || isRecordCancelMessage(message)) {
-    // Require an active recording that matches this requestId — otherwise a
-    // stray STOP/CANCEL (e.g. after teardown) would still run finishStop and
-    // clear overlay state even though nothing was capturing.
-    if (!state.activeRequestId || state.activeRequestId !== message.requestId) {
-      return false;
-    }
-    state.capture?.dispose();
-    state.setCapture(null);
-    const finishStop = () => {
-      state.onStop();
-      state.setActiveRequestId(null);
-    };
-    if (isRecordStopMessage(message) && sendResponse) {
-      const existingFlush = pendingStopFlushes.get(message.requestId);
-      if (existingFlush) {
-        void existingFlush.then(sendResponse);
-        return true;
-      }
-
-      const flush = deliveryFor(message.requestId)
-        .flush()
-        .then((succeeded): RecordStopAck => {
-          if (succeeded) {
-            stepDeliveries.delete(message.requestId);
-            finishStop();
-          }
-          return succeeded
-            ? { ok: true }
-            : {
-                ok: false,
-                error: "failed to deliver one or more recorded steps",
-              };
-        });
-      pendingStopFlushes.set(message.requestId, flush);
-      void flush.then(sendResponse).finally(() => {
-        if (pendingStopFlushes.get(message.requestId) === flush) {
-          pendingStopFlushes.delete(message.requestId);
-        }
-      });
-      return true;
-    }
-    if (isRecordCancelMessage(message)) {
-      stepDeliveries.delete(message.requestId);
-      pendingStopFlushes.delete(message.requestId);
-    }
-    finishStop();
-    return false;
-  }
-
-  return false;
-}
-
-export { RECORD_CANCEL, RECORD_START, RECORD_STEP, RECORD_STOP };

apps/extension/src/content/recording/frame-agent.ts

@@ -0,0 +1,209 @@
+import {
+  markRecordingDocument,
+  type RecordingDocumentMarker,
+  waitForDocumentElement,
+} from "@/lib/recording/document-marker";
+import {
+  isRecordFrameStartMessage,
+  RECORD_FRAME_PORT,
+  RECORD_FRAME_QUERY,
+  RECORD_FRAME_START,
+  type RecordFramePortMessage,
+  type RecordFrameQueryResponse,
+  type RecordFrameStartMessage,
+} from "@/lib/recording/frame-bridge";
+import { type RecordCaptureController, startRecordCapture } from "../record-capture";
+import { RecordStepDelivery } from "../record-step-delivery";
+
+interface ActiveFrameRecording {
+  requestId: string;
+  producerId: string;
+  port: chrome.runtime.Port;
+  delivery: RecordStepDelivery;
+  capture: RecordCaptureController;
+  marker: RecordingDocumentMarker;
+}
+
+const RECORD_FRAME_REGISTER_TIMEOUT_MS = 5_000;
+
+export class RecordFrameAgent {
+  #active: ActiveFrameRecording | null = null;
+  #startPromise: Promise<{ ok: true } | { ok: false; error: string }> | null = null;
+  #disposed = false;
+
+  async start(
+    message: RecordFrameStartMessage,
+  ): Promise<{ ok: true } | { ok: false; error: string }> {
+    if (this.#active?.requestId === message.requestId) return { ok: true };
+    if (this.#disposed) return { ok: false, error: "recording document is disposed" };
+    if (this.#startPromise) {
+      await this.#startPromise;
+      return this.start(message);
+    }
+    if (this.#active) this.cancel(this.#active.requestId);
+    const starting = this.#start(message);
+    this.#startPromise = starting;
+    try {
+      return await starting;
+    } finally {
+      if (this.#startPromise === starting) this.#startPromise = null;
+    }
+  }
+
+  cancel(requestId: string): void {
+    const active = this.#active;
+    if (!active || active.requestId !== requestId) return;
+    active.capture.dispose();
+    active.marker.restore();
+    active.port.disconnect();
+    this.#active = null;
+  }
+
+  dispose(): void {
+    this.#disposed = true;
+    if (this.#active) this.cancel(this.#active.requestId);
+  }
+
+  async #start(
+    message: RecordFrameStartMessage,
+  ): Promise<{ ok: true } | { ok: false; error: string }> {
+    const producerId = crypto.randomUUID();
+    const root = await waitForDocumentElement();
+    if (this.#disposed) return { ok: false, error: "recording document is disposed" };
+    const marker = markRecordingDocument(producerId, root);
+    const port = chrome.runtime.connect({ name: RECORD_FRAME_PORT });
+    try {
+      await registerPort(port, message.requestId, producerId);
+    } catch {
+      marker.restore();
+      port.disconnect();
+      return { ok: false, error: "failed to register recording document" };
+    }
+    if (this.#disposed) {
+      marker.restore();
+      port.disconnect();
+      return { ok: false, error: "recording document is disposed" };
+    }
+
+    const delivery = new RecordStepDelivery(message.requestId, undefined, producerId);
+    const capture = startRecordCapture(
+      message.requestId,
+      (step) => {
+        marker.ensure();
+        delivery.enqueue(step);
+      },
+      { captureNavigation: window.top === window },
+    );
+    const active: ActiveFrameRecording = {
+      requestId: message.requestId,
+      producerId,
+      port,
+      delivery,
+      capture,
+      marker,
+    };
+    this.#active = active;
+    port.onMessage.addListener((raw: unknown) => {
+      const command = raw as Partial<RecordFramePortMessage>;
+      if (command.type === "stop" && command.requestId === active.requestId) {
+        void this.#stop(active, command.commandId);
+      } else if (command.type === "cancel" && command.requestId === active.requestId) {
+        this.cancel(active.requestId);
+      }
+    });
+    port.onDisconnect.addListener(() => {
+      if (this.#active !== active) return;
+      active.capture.dispose();
+      active.marker.restore();
+      this.#active = null;
+    });
+    return { ok: true };
+  }
+
+  async #stop(active: ActiveFrameRecording, commandId: string | undefined): Promise<void> {
+    if (!commandId || this.#active !== active) return;
+    active.capture.dispose();
+    const succeeded = await active.delivery.flush();
+    try {
+      active.port.postMessage({
+        type: "stopped",
+        requestId: active.requestId,
+        commandId,
+        ok: succeeded,
+        ...(succeeded ? {} : { error: "failed to deliver one or more recorded steps" }),
+      } satisfies RecordFramePortMessage);
+    } catch {
+      return;
+    }
+    if (!succeeded || this.#active !== active) return;
+    active.marker.restore();
+    this.#active = null;
+    active.port.disconnect();
+  }
+}
+
+function registerPort(
+  port: chrome.runtime.Port,
+  requestId: string,
+  producerId: string,
+): Promise<void> {
+  return new Promise((resolve, reject) => {
+    const timer = setTimeout(() => {
+      cleanup();
+      reject(new Error("recording document registration timed out"));
+    }, RECORD_FRAME_REGISTER_TIMEOUT_MS);
+    const cleanup = () => {
+      clearTimeout(timer);
+      port.onMessage.removeListener(onMessage);
+      port.onDisconnect.removeListener(onDisconnect);
+    };
+    const onMessage = (raw: unknown) => {
+      const message = raw as Partial<RecordFramePortMessage>;
+      if (
+        message.type !== "ready_ack" ||
+        message.requestId !== requestId ||
+        message.producerId !== producerId
+      ) {
+        return;
+      }
+      cleanup();
+      resolve();
+    };
+    const onDisconnect = () => {
+      cleanup();
+      reject(new Error("recording document port disconnected"));
+    };
+    port.onMessage.addListener(onMessage);
+    port.onDisconnect.addListener(onDisconnect);
+    port.postMessage({ type: "ready", requestId, producerId } satisfies RecordFramePortMessage);
+  });
+}
+
+export function attachRecordFrameAgent(): () => void {
+  const agent = new RecordFrameAgent();
+  const onMessage = (
+    message: unknown,
+    _sender: chrome.runtime.MessageSender,
+    sendResponse: (response: { ok: true } | { ok: false; error: string }) => void,
+  ) => {
+    if (!isRecordFrameStartMessage(message)) return false;
+    void agent.start(message).then(sendResponse);
+    return true;
+  };
+  chrome.runtime.onMessage.addListener(onMessage);
+  void chrome.runtime
+    .sendMessage({ type: RECORD_FRAME_QUERY })
+    .then((response: RecordFrameQueryResponse | undefined) => {
+      if (!response?.active || !response.requestId || response.startedAtMs === undefined) return;
+      return agent.start({
+        type: RECORD_FRAME_START,
+        requestId: response.requestId,
+        startedAtMs: response.startedAtMs,
+      });
+    })
+    .catch(() => {});
+  return () => {
+    chrome.runtime.onMessage.removeListener(onMessage);
+    agent.dispose();
+  };
+}

apps/extension/src/entrypoints/background.ts

@@ -21,6 +21,7 @@ import {
   type OverlayMode,
 } from "@/lib/overlay-bridge";
 import { POPUP_PORT_NAME, type PopupInbound, type PopupOutbound } from "@/lib/popup-bridge";
+import { recordFrameCoordinator } from "@/lib/recording/frame-coordinator";
 import { attachSessionsLiveFlag } from "@/lib/sessions-live-flag";
 import { createDisconnectCleanup } from "@/session-manager/disconnect-cleanup";
 import { attachSessionEventHandler } from "@/session-manager/event-handler";
@@ -38,6 +39,7 @@ import {
   attachRecordFinishListener,
   attachRecordQueryListener,
   attachRecordStepListener,
+  type RecordRuntimeDeps,
 } from "@/tools/record";
 import { detectBrowserMeta } from "@/transport/handshake";
 import type { Transport } from "@/transport/transport";
@@ -145,10 +147,33 @@ export default defineBackground(() => {
       void sessionsLive.syncFromManager();
     },
   });
+  const recordDeps = {
+    tabsApi: chrome.tabs,
+    cdp,
+    frameCoordinator: recordFrameCoordinator,
+    sendToTab: (tabId: number, msg: Parameters<typeof chrome.tabs.sendMessage>[1]) =>
+      chrome.tabs.sendMessage(tabId, msg),
+    bypassOverlay: async (tabId: number, enabled: boolean) => {
+      try {
+        await chrome.tabs.sendMessage(tabId, {
+          type: OVERLAY_AUTOMATION_BYPASS,
+          enabled,
+        });
+      } catch {
+        // Content script may be unavailable on restricted pages.
+      }
+    },
+  } satisfies RecordRuntimeDeps;
+  recordFrameCoordinator.attach();
+  attachRecordStepListener(recordDeps);
+  attachRecordFinishListener(recordDeps);
+  attachRecordQueryListener(recordDeps);
+
   const dispatcher = new ToolDispatcher({
     transport,
     sessions,
     cdp,
+    recording: recordDeps,
     onSessionsChanged: onOverlaySessionStateChanged,
     onBrowserControlResumed,
     approveBorrow: (ctx) =>
@@ -170,28 +195,6 @@ export default defineBackground(() => {
     }),
   });
   dispatcher.start();
-  const recordDeps = {
-    tabsApi: chrome.tabs,
-    cdp,
-    sendToTab: (tabId: number, msg: Parameters<typeof chrome.tabs.sendMessage>[1]) =>
-      chrome.tabs.sendMessage(tabId, msg),
-    bypassOverlay: async (tabId: number, enabled: boolean) => {
-      try {
-        await chrome.tabs.sendMessage(tabId, {
-          type: OVERLAY_AUTOMATION_BYPASS,
-          enabled,
-        });
-      } catch {
-        // Content script may be unavailable on restricted pages.
-      }
-    },
-  };
-  // Message listeners stay up (cheap; fire only for record message types).
-  // Tab / webNavigation observation attaches lazily while a recording is
-  // active — see ensureBrowserObservationListeners in tools/record.ts.
-  attachRecordStepListener(recordDeps);
-  attachRecordFinishListener(recordDeps);
-  attachRecordQueryListener(recordDeps);
   if (typeof chrome.notifications?.onClicked?.addListener === "function") {
     attachBorrowNotificationClickHandler({
       onClicked: chrome.notifications.onClicked,

apps/extension/src/entrypoints/content.ts

@@ -11,11 +11,6 @@ import { createHelpRequestData } from "@/content/help-request";
 import overlayCss from "@/content/overlay.css?inline";
 import { OverlayController, shouldShowAgentControlOverlay } from "@/content/overlay-controller";
 import { RecordOverlay } from "@/content/RecordOverlay";
-import {
-  handleRecordContentMessage,
-  isRecordContentMessage,
-  type RecordCaptureController,
-} from "@/content/record-capture";
 import {
   type CaptureSuppressAck,
   type CaptureSuppressMessage,
@@ -45,11 +40,17 @@ import {
 } from "@/lib/overlay-bridge";
 import { sendInterrupt } from "@/lib/overlay-interrupt-client";
 import {
+  isRecordCancelMessage,
+  isRecordStartMessage,
+  isRecordStopMessage,
   RECORD_FINISH,
   RECORD_QUERY,
+  type RecordCancelMessage,
   type RecordQueryResponse,
   type RecordStartAck,
+  type RecordStartMessage,
   type RecordStopAck,
+  type RecordStopMessage,
 } from "@/lib/record-bridge";
 import type {
   BorrowCancelMessage,
@@ -69,7 +70,6 @@ export default defineContentScript({
     if (window.top !== window) return;
 
     const overlays = new OverlayController();
-    let recordCapture: RecordCaptureController | null = null;
     let activeRecordRequestId: string | null = null;
     let reactRoot: ReactDOM.Root | null = null;
     let overlayHost: HTMLElement | null = null;
@@ -228,8 +228,6 @@ export default defineContentScript({
       if (previousHelp) {
         void sendHelpFinish(previousHelp.id, "cancelled");
       }
-      recordCapture?.dispose();
-      recordCapture = null;
       activeRecordRequestId = null;
       renderAll();
     }
@@ -259,6 +257,9 @@ export default defineContentScript({
         | HelpRequestMessage
         | HelpCancelMessage
         | CaptureSuppressMessage
+        | RecordStartMessage
+        | RecordStopMessage
+        | RecordCancelMessage
         | OverlayAgentOverlayResetMessage
         | OverlayAgentStateMessage
         | OverlayAutomationBypassMessage,
@@ -269,41 +270,32 @@ export default defineContentScript({
         return captureSuppress.handleMessage(message, sendResponse);
       }
 
-      if (isRecordContentMessage(message)) {
-        const needsAsync = handleRecordContentMessage(
-          message,
-          {
-            activeRequestId: activeRecordRequestId,
-            capture: recordCapture,
-            setActiveRequestId: (id) => {
-              activeRecordRequestId = id;
-            },
-            setCapture: (capture) => {
-              recordCapture = capture;
-            },
-            onStart: (requestId, startedAtMs) => {
-              overlays.setAgentRecordRequest({
-                id: requestId,
-                ...(typeof startedAtMs === "number" ? { startedAtMs } : {}),
-                onFinish: () => {
-                  void chrome.runtime.sendMessage({
-                    type: RECORD_FINISH,
-                    requestId,
-                  });
-                },
-              });
-              renderAll();
-            },
-            onStop: () => {
-              overlays.clearAgentRecordRequest(activeRecordRequestId ?? undefined);
-              renderAll();
-            },
+      if (isRecordStartMessage(message)) {
+        activeRecordRequestId = message.requestId;
+        overlays.setAgentRecordRequest({
+          id: message.requestId,
+          ...(typeof message.startedAtMs === "number" ? { startedAtMs: message.startedAtMs } : {}),
+          onFinish: () => {
+            void chrome.runtime.sendMessage({
+              type: RECORD_FINISH,
+              requestId: message.requestId,
+            });
           },
-          sendResponse as unknown as
-            | ((response: RecordStartAck | RecordStopAck) => void)
-            | undefined,
-        );
-        return needsAsync;
+        });
+        renderAll();
+        (sendResponse as unknown as (response: RecordStartAck) => void)({ ok: true });
+        return false;
+      }
+
+      if (isRecordStopMessage(message) || isRecordCancelMessage(message)) {
+        if (activeRecordRequestId !== message.requestId) return false;
+        overlays.clearAgentRecordRequest(message.requestId);
+        activeRecordRequestId = null;
+        renderAll();
+        if (isRecordStopMessage(message)) {
+          (sendResponse as unknown as (response: RecordStopAck) => void)({ ok: true });
+        }
+        return false;
       }
 
       if (
@@ -526,9 +518,6 @@ export default defineContentScript({
       chrome.runtime.onMessage.removeListener(onMessage);
       chrome.storage.onChanged.removeListener(onStorageChange);
       window.removeEventListener("pageshow", onPageShow);
-      // Restore history hooks / remove capture listeners before the CS unloads.
-      recordCapture?.dispose();
-      recordCapture = null;
       activeRecordRequestId = null;
     });
   },

apps/extension/src/entrypoints/record-frame.content.ts

@@ -0,0 +1,14 @@
+import { attachRecordFrameAgent } from "@/content/recording/frame-agent";
+
+export default defineContentScript({
+  matches: ["<all_urls>"],
+  runAt: "document_start",
+  allFrames: true,
+  matchAboutBlank: true,
+  matchOriginAsFallback: true,
+
+  main(ctx) {
+    const dispose = attachRecordFrameAgent();
+    ctx.onInvalidated(dispose);
+  },
+});

apps/extension/src/lib/__tests__/record-frame-coordinator.test.ts

@@ -0,0 +1,213 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import { RECORD_FRAME_PORT, RECORD_FRAME_QUERY } from "../recording/frame-bridge";
+import { RecordFrameCoordinator } from "../recording/frame-coordinator";
+
+class ListenerSet<T extends (...args: never[]) => unknown> {
+  readonly listeners = new Set<T>();
+  addListener = (listener: T) => this.listeners.add(listener);
+  removeListener = (listener: T) => this.listeners.delete(listener);
+}
+
+function fakePort(sender: chrome.runtime.MessageSender) {
+  const messages: unknown[] = [];
+  const onMessage = new ListenerSet<(message: unknown) => void>();
+  const onDisconnect = new ListenerSet<() => void>();
+  return {
+    port: {
+      name: RECORD_FRAME_PORT,
+      sender,
+      onMessage,
+      onDisconnect,
+      postMessage: vi.fn((message: unknown) => messages.push(message)),
+      disconnect: vi.fn(),
+    } as unknown as chrome.runtime.Port,
+    messages,
+    receive(message: unknown) {
+      for (const listener of onMessage.listeners) listener(message);
+    },
+  };
+}
+
+describe("RecordFrameCoordinator", () => {
+  const onConnect = new ListenerSet<(port: chrome.runtime.Port) => void>();
+  const onMessage = new ListenerSet<
+    (
+      message: unknown,
+      sender: chrome.runtime.MessageSender,
+      sendResponse: (response: unknown) => void,
+    ) => boolean
+  >();
+
+  beforeEach(() => {
+    onConnect.listeners.clear();
+    onMessage.listeners.clear();
+    vi.stubGlobal("chrome", {
+      runtime: { onConnect, onMessage },
+    });
+  });
+
+  it("answers child-document queries for the initial tab before it is armed", () => {
+    const coordinator = new RecordFrameCoordinator({
+      getAllFrames: async () => [],
+      sendToDocument: async () => ({ ok: true }),
+    });
+    coordinator.attach();
+    coordinator.begin("rec-1", 10, 3);
+
+    const query = (tabId: number) => {
+      let response: unknown;
+      for (const listener of onMessage.listeners) {
+        listener(
+          { type: RECORD_FRAME_QUERY },
+          {
+            tab: { id: tabId },
+            frameId: 7,
+            documentId: "child-document",
+          } as chrome.runtime.MessageSender,
+          (value) => {
+            response = value;
+          },
+        );
+      }
+      return response;
+    };
+
+    expect(query(3)).toEqual({ active: true, requestId: "rec-1", startedAtMs: 10 });
+    expect(query(4)).toEqual({ active: false });
+  });
+
+  it("starts a child Document that appears after the initial frame snapshot", async () => {
+    let notifyFrameNavigation:
+      | ((frame: {
+          tabId: number;
+          frameId: number;
+          documentId?: string;
+          lifecycle: "committed" | "completed";
+        }) => void)
+      | undefined;
+    const sendToDocument = vi.fn(async () => ({ ok: true }));
+    const coordinator = new RecordFrameCoordinator({
+      getAllFrames: async () => [{ frameId: 0, documentId: "top-document" }],
+      sendToDocument,
+      subscribeFrameNavigation(listener) {
+        notifyFrameNavigation = listener;
+        return () => {};
+      },
+    });
+    coordinator.attach();
+    const onDocumentReady = vi.fn();
+    coordinator.begin("rec-1", 10, 3, onDocumentReady);
+    await coordinator.armTab("rec-1", 3);
+    sendToDocument.mockClear();
+
+    notifyFrameNavigation?.({
+      tabId: 3,
+      frameId: 7,
+      documentId: "late-child",
+      lifecycle: "completed",
+    });
+    await vi.waitFor(() => {
+      expect(sendToDocument).toHaveBeenCalledWith(
+        3,
+        { type: "bsk-record-frame-start", requestId: "rec-1", startedAtMs: 10 },
+        { documentId: "late-child" },
+      );
+    });
+    expect(onDocumentReady).not.toHaveBeenCalled();
+
+    const child = fakePort({
+      tab: { id: 3 },
+      frameId: 7,
+      documentId: "late-child",
+    } as chrome.runtime.MessageSender);
+    for (const listener of onConnect.listeners) listener(child.port);
+    child.receive({ type: "ready", requestId: "rec-1", producerId: "producer-1" });
+    notifyFrameNavigation?.({
+      tabId: 3,
+      frameId: 7,
+      documentId: "late-child",
+      lifecycle: "completed",
+    });
+    await vi.waitFor(() => {
+      expect(onDocumentReady).toHaveBeenCalledWith({
+        tabId: 3,
+        documentId: "late-child",
+        browserFrameId: 7,
+        producerId: "producer-1",
+      });
+    });
+  });
+
+  it("binds a producer to its sender Document and keeps final steps valid while stopping", async () => {
+    const sendToDocument = vi.fn(async () => ({ ok: true }));
+    const coordinator = new RecordFrameCoordinator({
+      getAllFrames: async () => [
+        { frameId: 0, documentId: "top-document" },
+        { frameId: 7, documentId: "child-document" },
+      ],
+      sendToDocument,
+    });
+    coordinator.attach();
+    coordinator.begin("rec-1", 10, 3);
+    await expect(coordinator.armTab("rec-1", 3)).resolves.toBe(true);
+
+    const sender = {
+      tab: { id: 3 },
+      frameId: 7,
+      documentId: "child-document",
+    } as chrome.runtime.MessageSender;
+    const frame = fakePort(sender);
+    for (const listener of onConnect.listeners) listener(frame.port);
+    frame.receive({ type: "ready", requestId: "rec-1", producerId: "producer-1" });
+
+    expect(coordinator.sourceFor("rec-1", "producer-1", sender)).toEqual({
+      tabId: 3,
+      documentId: "child-document",
+      browserFrameId: 7,
+      producerId: "producer-1",
+    });
+
+    const stopping = coordinator.stop("rec-1");
+    expect(coordinator.sourceFor("rec-1", "producer-1", sender)).not.toBeNull();
+    const stop = frame.messages.find(
+      (message): message is { type: "stop"; commandId: string } =>
+        typeof message === "object" &&
+        message !== null &&
+        (message as { type?: string }).type === "stop",
+    );
+    expect(stop).toBeDefined();
+    frame.receive({
+      type: "stopped",
+      requestId: "rec-1",
+      commandId: stop!.commandId,
+      ok: true,
+    });
+    await expect(stopping).resolves.toBe(true);
+    expect(coordinator.sourceFor("rec-1", "producer-1", sender)).toBeNull();
+  });
+
+  it("rejects a producer used from another Document", async () => {
+    const coordinator = new RecordFrameCoordinator({
+      getAllFrames: async () => [{ frameId: 0, documentId: "top-document" }],
+      sendToDocument: async () => ({ ok: true }),
+    });
+    coordinator.attach();
+    coordinator.begin("rec-1", 10, 3);
+    await coordinator.armTab("rec-1", 3);
+    const sender = {
+      tab: { id: 3 },
+      frameId: 0,
+      documentId: "top-document",
+    } as chrome.runtime.MessageSender;
+    const frame = fakePort(sender);
+    for (const listener of onConnect.listeners) listener(frame.port);
+    frame.receive({ type: "ready", requestId: "rec-1", producerId: "producer-1" });
+
+    expect(
+      coordinator.sourceFor("rec-1", "producer-1", {
+        ...sender,
+        documentId: "other-document",
+      }),
+    ).toBeNull();
+  });
+});

apps/extension/src/lib/__tests__/recording-document-marker.test.ts

@@ -0,0 +1,70 @@
+import { describe, expect, it } from "vitest";
+import {
+  RECORD_DOCUMENT_ATTRIBUTE,
+  recordingDocumentMarkerValue,
+} from "@/shared/recording-document-identity";
+import { markRecordingDocument } from "../recording/document-marker";
+import { ObservationNodeIndex } from "../recording/observation-capture";
+
+describe("recording document marker", () => {
+  it("rejects a non-random Document identity", () => {
+    expect(() => markRecordingDocument("user@example.com")).toThrow(
+      "recording Document identity must be a random UUID",
+    );
+  });
+
+  it("restores the Document attribute exactly", () => {
+    document.documentElement.setAttribute(RECORD_DOCUMENT_ATTRIBUTE, "page-value");
+    const producerId = "123e4567-e89b-42d3-a456-426614174000";
+    const marker = markRecordingDocument(producerId);
+
+    expect(document.documentElement.getAttribute(RECORD_DOCUMENT_ATTRIBUTE)).toBe(
+      recordingDocumentMarkerValue(producerId),
+    );
+    marker.restore();
+    expect(document.documentElement.getAttribute(RECORD_DOCUMENT_ATTRIBUTE)).toBe("page-value");
+    document.documentElement.removeAttribute(RECORD_DOCUMENT_ATTRIBUTE);
+  });
+
+  it("indexes the CDP scope from the safe frame identity", () => {
+    const index = new ObservationNodeIndex({
+      rootFrameId: "root",
+      frames: [
+        {
+          frameId: "child",
+          target: { tabId: 3, sessionId: "oopif-session" },
+          recordingDocumentId: "producer-1",
+        },
+      ],
+      matchNodes: [],
+      refs: [],
+    });
+
+    expect(index.documentScope("producer-1")).toEqual({
+      frameId: "child",
+      target: { tabId: 3, sessionId: "oopif-session" },
+    });
+  });
+
+  it("fails closed when a recording identity maps to multiple Documents", () => {
+    const index = new ObservationNodeIndex({
+      rootFrameId: "root",
+      frames: [
+        {
+          frameId: "left",
+          target: { tabId: 3, sessionId: "left-session" },
+          recordingDocumentId: "duplicate",
+        },
+        {
+          frameId: "right",
+          target: { tabId: 3, sessionId: "right-session" },
+          recordingDocumentId: "duplicate",
+        },
+      ],
+      matchNodes: [],
+      refs: [],
+    });
+
+    expect(index.documentScope("duplicate")).toBeUndefined();
+  });
+});

apps/extension/src/lib/__tests__/recording-runtime.test.ts

@@ -2,20 +2,27 @@ import { afterEach, describe, expect, it, vi } from "vitest";
 import type { CdpRunner, ChromeTabsApi } from "@/tools/shared";
 
 const captureRecordingObservation = vi.hoisted(() => vi.fn());
+const waitForDocumentSettled = vi.hoisted(() => vi.fn(async () => "quiet" as const));
 
 vi.mock("../recording/observation-capture", async (importOriginal) => {
   const actual = await importOriginal<typeof import("../recording/observation-capture")>();
   return { ...actual, captureRecordingObservation };
 });
 
+vi.mock("../recording/document-settle", async (importOriginal) => {
+  const actual = await importOriginal<typeof import("../recording/document-settle")>();
+  return { ...actual, waitForDocumentSettled };
+});
+
 import { ObservationNodeIndex } from "../recording/observation-capture";
 import { RecordingObservationRuntime } from "../recording/recording-runtime";
+import type { RecordingDraftStep } from "../recording/types";
 
-function observation() {
+function observation(url = "https://example.com/") {
   return {
     rootFrameId: "root",
     index: new ObservationNodeIndex({ rootFrameId: "root", matchNodes: [], refs: [] }),
-    url: "https://example.com/",
+    url,
     title: "Example",
     vomText: '@vom 1\nRootWebArea "Example"',
     truncated: false,
@@ -30,7 +37,10 @@ function runtime(): RecordingObservationRuntime {
 }
 
 describe("RecordingObservationRuntime", () => {
-  afterEach(() => captureRecordingObservation.mockReset());
+  afterEach(() => {
+    captureRecordingObservation.mockReset();
+    waitForDocumentSettled.mockClear();
+  });
 
   it("shares one initial capture and includes it in flush", async () => {
     let release!: (value: ReturnType<typeof observation>) => void;
@@ -130,4 +140,150 @@ describe("RecordingObservationRuntime", () => {
     expect(dumped).not.toContain("backendNodeId");
     expect(dumped).not.toContain("ObservationNodeIndex");
   });
+
+  it("captures a tab transition without sharing observation cursors", async () => {
+    captureRecordingObservation
+      .mockResolvedValueOnce(observation("https://example.com/first"))
+      .mockResolvedValueOnce(observation("https://example.com/second"));
+    const recording = runtime();
+
+    await recording.captureInitial(4);
+    const transition = await recording.captureTabTransition(4, 5);
+    await recording.captureInitial(4);
+    await recording.captureInitial(5);
+
+    expect(transition).toEqual({
+      preStateId: "s1",
+      postStateId: "s2",
+      targetUrl: "https://example.com/second",
+    });
+    expect(captureRecordingObservation.mock.calls.map(([input]) => input.tabId)).toEqual([4, 5]);
+  });
+
+  it("binds an iframe draft to its marked CDP Document scope", async () => {
+    captureRecordingObservation.mockResolvedValueOnce({
+      ...observation(),
+      index: new ObservationNodeIndex({
+        rootFrameId: "root",
+        frames: [
+          {
+            frameId: "child",
+            target: { tabId: 7, sessionId: "oopif-session" },
+            recordingDocumentId: "producer-1",
+          },
+        ],
+        matchNodes: [
+          {
+            backendNodeId: 42,
+            frameId: "child",
+            tag: "button",
+            rect: { x: 410, y: 20, w: 100, h: 30 },
+            localRect: { x: 10, y: 20, w: 100, h: 30 },
+          },
+        ],
+        refs: [{ ref: "e1", backendNodeId: 42, frameId: "child", line: 1 }],
+      }),
+    });
+    const recording = runtime();
+    const drafts: RecordingDraftStep[] = [
+      {
+        op: "click" as const,
+        captureTarget: { tag: "button", role: "button", name: "Save" },
+        targetHint: {
+          geometry: { rect: { x: 10, y: 20, w: 100, h: 30 }, tag: "button" },
+        },
+      },
+    ];
+
+    await recording.captureInitial(7);
+    await recording.processDraft(7, drafts, 0, "producer-1");
+    recording.cancel();
+
+    const draft = drafts[0];
+    expect(draft?.op).toBe("click");
+    if (!draft || draft.op !== "click") throw new Error("expected click draft");
+    expect(draft.targetHint).toMatchObject({
+      frameId: "child",
+      geometrySpace: "local",
+    });
+    expect(draft.matchedTarget?.ref).toBe("e1");
+  });
+
+  it("refreshes a late iframe before matching its first action", async () => {
+    const iframeObservation = {
+      ...observation(),
+      index: new ObservationNodeIndex({
+        rootFrameId: "root",
+        frames: [
+          {
+            frameId: "child",
+            target: { tabId: 7, sessionId: "oopif-session" },
+            recordingDocumentId: "producer-1",
+          },
+        ],
+        matchNodes: [
+          {
+            backendNodeId: 42,
+            frameId: "child",
+            tag: "button",
+            rect: { x: 410, y: 20, w: 100, h: 30 },
+            localRect: { x: 10, y: 20, w: 100, h: 30 },
+          },
+        ],
+        refs: [
+          {
+            ref: "e1",
+            backendNodeId: 42,
+            frameId: "child",
+            role: "button",
+            name: "表格视图",
+            line: 1,
+          },
+        ],
+      }),
+    };
+    captureRecordingObservation
+      .mockResolvedValueOnce(observation())
+      .mockResolvedValueOnce(iframeObservation)
+      .mockResolvedValueOnce(iframeObservation);
+    const recording = runtime();
+
+    await recording.captureInitial(7);
+    await recording.refreshDocument(7, "producer-1");
+    const drafts: RecordingDraftStep[] = [
+      {
+        op: "click",
+        captureTarget: { tag: "button", role: "button", name: "表格视图" },
+        targetHint: {
+          geometry: { rect: { x: 10, y: 20, w: 100, h: 30 }, tag: "button" },
+        },
+      },
+    ];
+    await recording.processDraft(7, drafts, 0, "producer-1");
+    recording.cancel();
+
+    expect(captureRecordingObservation).toHaveBeenCalledTimes(3);
+    expect(waitForDocumentSettled).toHaveBeenCalledWith(
+      expect.anything(),
+      { frameId: "child", target: { tabId: 7, sessionId: "oopif-session" } },
+      { signal: expect.any(AbortSignal) },
+    );
+    const draft = drafts[0];
+    expect(draft?.op).toBe("click");
+    if (!draft || draft.op !== "click") throw new Error("expected click draft");
+    expect(draft.matchedTarget).toMatchObject({ ref: "e1", name: "表格视图" });
+  });
+
+  it("does not poison final flush when a frame readiness refresh fails", async () => {
+    captureRecordingObservation
+      .mockResolvedValueOnce(observation())
+      .mockRejectedValueOnce(new Error("child Document replaced"));
+    const recording = runtime();
+
+    await recording.captureInitial(7);
+    await expect(recording.refreshDocument(7, "producer-1")).rejects.toThrow(
+      "child Document replaced",
+    );
+    await expect(recording.flush()).resolves.toBeUndefined();
+  });
 });

apps/extension/src/lib/__tests__/step-buffer.test.ts

@@ -3,7 +3,7 @@ import { appendRecordedPayload, observeRecordedNavigation } from "../recording/s
 
 describe("recording-step-buffer", () => {
   it("stores semantic click without summary", () => {
-    const buffer = { steps: [], pendingNavigation: false };
+    const buffer = { steps: [], navigation: { pendingNavigation: false } };
     appendRecordedPayload(buffer, {
       op: "click",
       target: { tag: "button", role: "button", name: "发布" },
@@ -15,11 +15,11 @@ describe("recording-step-buffer", () => {
         captureTarget: { tag: "button", role: "button", name: "发布" },
       },
     ]);
-    expect(buffer.pendingNavigation).toBe(true);
+    expect(buffer.navigation.pendingNavigation).toBe(true);
   });
 
   it("keeps the hovered element description as a capture fallback", () => {
-    const buffer = { steps: [], pendingNavigation: false };
+    const buffer = { steps: [], navigation: { pendingNavigation: false } };
     appendRecordedPayload(
       buffer,
       {
@@ -59,9 +59,11 @@ describe("recording-step-buffer", () => {
           captureTarget: { tag: "button", role: "button", name: "发布" },
         },
       ],
-      currentUrl: "https://example.com/a",
-      pendingNavigation: true,
-      pendingNavigationDeadline: Date.now() + 5_000,
+      navigation: {
+        currentUrl: "https://example.com/a",
+        pendingNavigation: true,
+        pendingNavigationDeadline: Date.now() + 5_000,
+      },
     };
     observeRecordedNavigation(buffer, "https://example.com/b", true);
     expect(buffer.steps).toEqual([
@@ -83,9 +85,11 @@ describe("recording-step-buffer", () => {
           values: ["tech"],
         },
       ],
-      currentUrl: "https://example.com/list",
-      pendingNavigation: true,
-      pendingNavigationDeadline: Date.now() + 5_000,
+      navigation: {
+        currentUrl: "https://example.com/list",
+        pendingNavigation: true,
+        pendingNavigationDeadline: Date.now() + 5_000,
+      },
     };
     observeRecordedNavigation(buffer, "https://example.com/list?cat=tech", true);
     expect(buffer.steps).toEqual([
@@ -101,8 +105,7 @@ describe("recording-step-buffer", () => {
   it("emits navigate for uncaused URL changes", () => {
     const buffer = {
       steps: [],
-      currentUrl: "https://example.com/a",
-      pendingNavigation: false,
+      navigation: { currentUrl: "https://example.com/a", pendingNavigation: false },
     };
     const result = observeRecordedNavigation(buffer, "https://example.com/b", false);
     expect(result).toEqual({ kind: "appended", index: 0 });
@@ -115,8 +118,10 @@ describe("recording-step-buffer", () => {
   it("asks the recorder to coalesce redirect hops instead of emitting each one", () => {
     const buffer = {
       steps: [],
-      currentUrl: "https://passport.example/login",
-      pendingNavigation: false,
+      navigation: {
+        currentUrl: "https://passport.example/login",
+        pendingNavigation: false,
+      },
     };
     const hop1 = observeRecordedNavigation(
       buffer,
@@ -139,14 +144,16 @@ describe("recording-step-buffer", () => {
       url: "https://app.example/dashboard",
     });
     expect(buffer.steps).toEqual([]);
-    expect(buffer.currentUrl).toBe("https://app.example/dashboard");
+    expect(buffer.navigation.currentUrl).toBe("https://app.example/dashboard");
   });
 
   it("does not reuse redirect metadata for a later content-observed URL change", () => {
     const buffer = {
       steps: [],
-      currentUrl: "https://example.com/redirect",
-      pendingNavigation: false,
+      navigation: {
+        currentUrl: "https://example.com/redirect",
+        pendingNavigation: false,
+      },
     };
 
     const result = observeRecordedNavigation(buffer, "https://example.com/spa");

apps/extension/src/lib/__tests__/tab-coordinator.test.ts

@@ -0,0 +1,39 @@
+import { describe, expect, it } from "vitest";
+import { RecordingTabCoordinator } from "../recording/tab-coordinator";
+
+describe("RecordingTabCoordinator", () => {
+  it("keeps navigation state isolated per tab", () => {
+    const tabs = new RecordingTabCoordinator(4, "https://example.com/first");
+    const first = tabs.navigation(4);
+    first.pendingNavigation = true;
+    const second = tabs.navigation(5, "https://example.com/second");
+
+    expect(second).toEqual({
+      currentUrl: "https://example.com/second",
+      pendingNavigation: false,
+    });
+    expect(tabs.navigation(4)).toBe(first);
+    expect(tabs.navigation(4).pendingNavigation).toBe(true);
+  });
+
+  it("invalidates an earlier activation when a newer tab becomes active", () => {
+    const tabs = new RecordingTabCoordinator(4);
+    const second = tabs.noteActivation(5);
+    const third = tabs.noteActivation(6);
+
+    expect(tabs.isLatest(second)).toBe(false);
+    expect(tabs.isLatest(third)).toBe(true);
+    tabs.commit(6);
+    expect(tabs.currentTabId).toBe(6);
+  });
+
+  it("commits the freshly observed URL when returning to an existing tab", () => {
+    const tabs = new RecordingTabCoordinator(4);
+    tabs.navigation(5, "https://example.com/old");
+
+    tabs.commit(5, "https://example.com/new");
+
+    expect(tabs.currentTabId).toBe(5);
+    expect(tabs.navigation(5).currentUrl).toBe("https://example.com/new");
+  });
+});

apps/extension/src/lib/__tests__/target-matcher.test.ts

@@ -69,6 +69,23 @@ describe("matchObservationTarget", () => {
     expect(target.ref).toBe("e2");
   });
 
+  it("matches iframe capture geometry in the child viewport coordinate space", () => {
+    const child = node(42, "child", 410);
+    child.localRect = { x: 10, y: 20, w: 100, h: 30 };
+    const target = matchObservationTarget({
+      observation: observation(
+        [child],
+        [{ ref: "e1", backendNodeId: 42, frameId: "child", line: 1 }],
+      ),
+      hint: {
+        frameId: "child",
+        geometrySpace: "local",
+        geometry: { rect: { x: 10, y: 20, w: 100, h: 30 }, tag: "button" },
+      },
+    });
+    expect(target.ref).toBe("e1");
+  });
+
   it("restricts a missing frame hint to the root frame", () => {
     const target = matchObservationTarget({
       observation: observation(
@@ -81,6 +98,21 @@ describe("matchObservationTarget", () => {
     expect(target).toEqual({ name: "发布", unmatched: true });
   });
 
+  it("fails closed when the source Document has no VOM frame mapping", () => {
+    const target = matchObservationTarget({
+      observation: observation(
+        [node(42, "root")],
+        [{ ref: "e1", backendNodeId: 42, role: "button", name: "发布", line: 1 }],
+      ),
+      hint: {
+        frameId: null,
+        geometry: { rect: { x: 10, y: 20, w: 100, h: 30 }, tag: "button" },
+      },
+      fallback: { tag: "button", role: "button", name: "发布" },
+    });
+    expect(target).toEqual({ role: "button", name: "发布", unmatched: true });
+  });
+
   it("returns unmatched for ambiguous geometry", () => {
     const target = matchObservationTarget({
       observation: observation(

apps/extension/src/lib/__tests__/trace-reducer-v2.test.ts

@@ -27,6 +27,17 @@ describe("shouldRecordPress", () => {
 });
 
 describe("reduceTraceSteps", () => {
+  it("does not expose internal tab transitions in trace v2", () => {
+    const trace = reduceTraceSteps([
+      {
+        op: "switch_tab",
+        preStateId: "s1",
+        postStateId: "s2",
+      },
+    ]);
+    expect(trace.steps).toEqual([]);
+  });
+
   it("builds steps with pages dictionary and page id references", () => {
     const drafts: RecordingDraftStep[] = [
       {
@@ -160,7 +171,7 @@ describe("reduceTraceSteps", () => {
     });
   });
 
-  it("keeps hover steps before menu clicks", () => {
+  it("drops hover steps, which only exist in trace v3", () => {
     const { steps } = reduceTraceSteps(
       [
         {
@@ -176,12 +187,7 @@ describe("reduceTraceSteps", () => {
       ],
       "https://example.com/app",
     );
-    expect(steps.map((s) => s.op)).toEqual(["hover", "click"]);
-    expect(steps[0]).toMatchObject({
-      op: "hover",
-      page: "p1",
-      target: { name: "Account" },
-    });
+    expect(steps.map((s) => s.op)).toEqual(["click"]);
   });
 
   it("resolveTraceStartUrl prefers explicit start URL", () => {

apps/extension/src/lib/__tests__/trace-reducer-v3.test.ts

@@ -33,6 +33,49 @@ describe("trace reducer v3", () => {
     expect(JSON.stringify(reduced.steps)).not.toContain("private-account-id");
   });
 
+  it("emits tab transitions only for callers that advertised support", () => {
+    const drafts: RecordingDraftStep[] = [
+      {
+        op: "switch_tab",
+        preStateId: "s1",
+        postStateId: "s2",
+      },
+    ];
+
+    expect(reduceTraceStepsV3(drafts).steps).toEqual([]);
+    expect(reduceTraceStepsV3(drafts, { includeTabSwitches: true }).steps).toEqual([
+      { op: "switch_tab", id: 1, state: "s1", result: { state: "s2" } },
+    ]);
+  });
+
+  it("keeps hover steps before menu clicks", () => {
+    const drafts: RecordingDraftStep[] = [
+      {
+        op: "hover",
+        captureTarget: { tag: "span", role: "button", name: "Account" },
+        preStateId: "s1",
+        postStateId: "s1",
+      },
+      {
+        op: "click",
+        captureTarget: { tag: "a", role: "link", name: "Profile" },
+        preStateId: "s1",
+        postStateId: "s1",
+      },
+    ];
+
+    expect(reduceTraceStepsV3(drafts).steps.map((s) => s.op)).toEqual(["hover", "click"]);
+  });
+
+  it("does not export a tab transition without both observation endpoints", () => {
+    const sourceOnly: RecordingDraftStep = { op: "switch_tab", preStateId: "s1" };
+    const targetOnly: RecordingDraftStep = { op: "switch_tab", postStateId: "s2" };
+
+    expect(
+      reduceTraceStepsV3([sourceOnly, targetOnly], { includeTabSwitches: true }).steps,
+    ).toEqual([]);
+  });
+
   it("collapses redirect hops while retaining draft-to-step identity", () => {
     const drafts: RecordingDraftStep[] = [
       { op: "navigate", url: "https://example.com/start", preStateId: "s1", postStateId: "s2" },

apps/extension/src/lib/recording/document-marker.ts

@@ -0,0 +1,39 @@
+import {
+  RECORD_DOCUMENT_ATTRIBUTE,
+  recordingDocumentMarkerValue,
+} from "@/shared/recording-document-identity";
+
+export interface RecordingDocumentMarker {
+  restore(): void;
+  ensure(): void;
+}
+
+export function waitForDocumentElement(): Promise<HTMLElement> {
+  if (document.documentElement) return Promise.resolve(document.documentElement);
+  return new Promise((resolve) => {
+    const observer = new MutationObserver(() => {
+      if (!document.documentElement) return;
+      observer.disconnect();
+      resolve(document.documentElement);
+    });
+    observer.observe(document, { childList: true });
+  });
+}
+
+export function markRecordingDocument(
+  producerId: string,
+  root: HTMLElement = document.documentElement,
+): RecordingDocumentMarker {
+  const previous = root.getAttribute(RECORD_DOCUMENT_ATTRIBUTE);
+  const markerValue = recordingDocumentMarkerValue(producerId);
+  const ensure = () => root.setAttribute(RECORD_DOCUMENT_ATTRIBUTE, markerValue);
+  ensure();
+  return {
+    ensure,
+    restore() {
+      if (root.getAttribute(RECORD_DOCUMENT_ATTRIBUTE) !== markerValue) return;
+      if (previous === null) root.removeAttribute(RECORD_DOCUMENT_ATTRIBUTE);
+      else root.setAttribute(RECORD_DOCUMENT_ATTRIBUTE, previous);
+    },
+  };
+}

apps/extension/src/lib/recording/frame-bridge.ts

@@ -0,0 +1,65 @@
+export const RECORD_FRAME_PORT = "bsk-record-frame";
+export const RECORD_FRAME_QUERY = "bsk-record-frame-query";
+export const RECORD_FRAME_START = "bsk-record-frame-start";
+
+export interface RecordFrameQueryMessage {
+  type: typeof RECORD_FRAME_QUERY;
+}
+
+export interface RecordFrameQueryResponse {
+  active: boolean;
+  requestId?: string;
+  startedAtMs?: number;
+}
+
+export interface RecordFrameStartMessage {
+  type: typeof RECORD_FRAME_START;
+  requestId: string;
+  startedAtMs: number;
+}
+
+export type RecordFramePortMessage =
+  | {
+      type: "ready";
+      requestId: string;
+      producerId: string;
+    }
+  | {
+      type: "ready_ack";
+      requestId: string;
+      producerId: string;
+    }
+  | {
+      type: "stop";
+      requestId: string;
+      commandId: string;
+    }
+  | {
+      type: "cancel";
+      requestId: string;
+    }
+  | {
+      type: "stopped";
+      requestId: string;
+      commandId: string;
+      ok: boolean;
+      error?: string;
+    };
+
+export function isRecordFrameQueryMessage(value: unknown): value is RecordFrameQueryMessage {
+  return (
+    typeof value === "object" &&
+    value !== null &&
+    (value as { type?: unknown }).type === RECORD_FRAME_QUERY
+  );
+}
+
+export function isRecordFrameStartMessage(value: unknown): value is RecordFrameStartMessage {
+  if (typeof value !== "object" || value === null) return false;
+  const message = value as Partial<RecordFrameStartMessage>;
+  return (
+    message.type === RECORD_FRAME_START &&
+    typeof message.requestId === "string" &&
+    typeof message.startedAtMs === "number"
+  );
+}

apps/extension/src/lib/recording/frame-coordinator.ts

@@ -0,0 +1,399 @@
+import {
+  isRecordFrameQueryMessage,
+  RECORD_FRAME_PORT,
+  RECORD_FRAME_START,
+  type RecordFramePortMessage,
+  type RecordFrameQueryResponse,
+  type RecordFrameStartMessage,
+} from "./frame-bridge";
+
+export interface RecordingCaptureScope {
+  tabId: number;
+  documentId: string;
+  browserFrameId: number;
+  producerId: string;
+}
+
+interface ArmedRecording {
+  requestId: string;
+  startedAtMs: number;
+  tabIds: Set<number>;
+  agents: Map<string, FrameAgent>;
+  onDocumentReady?: (scope: RecordingCaptureScope) => void | Promise<void>;
+  finishing: boolean;
+}
+
+interface FrameAgent extends RecordingCaptureScope {
+  requestId: string;
+  port: chrome.runtime.Port;
+  stopWaiters: Map<string, (ok: boolean) => void>;
+}
+
+interface BrowserFrame {
+  frameId: number;
+  documentId?: string;
+}
+
+interface BrowserFrameNavigation extends BrowserFrame {
+  tabId: number;
+  lifecycle: "committed" | "completed";
+}
+
+const RECORD_FRAME_STOP_TIMEOUT_MS = 5_000;
+
+export interface RecordFrameCoordinatorDeps {
+  getAllFrames(tabId: number): Promise<BrowserFrame[]>;
+  sendToDocument(
+    tabId: number,
+    message: RecordFrameStartMessage,
+    target: { documentId?: string; frameId?: number },
+  ): Promise<unknown>;
+  subscribeFrameNavigation?(listener: (frame: BrowserFrameNavigation) => void): () => void;
+}
+
+function documentKey(tabId: number, documentId: string): string {
+  return `${tabId}:${documentId}`;
+}
+
+function senderAddress(
+  sender: chrome.runtime.MessageSender,
+): { tabId: number; documentId: string; browserFrameId: number } | null {
+  const tabId = sender.tab?.id;
+  const documentId = sender.documentId;
+  const browserFrameId = sender.frameId;
+  if (
+    typeof tabId !== "number" ||
+    typeof documentId !== "string" ||
+    typeof browserFrameId !== "number"
+  ) {
+    return null;
+  }
+  return { tabId, documentId, browserFrameId };
+}
+
+function defaultDeps(): RecordFrameCoordinatorDeps {
+  return {
+    async getAllFrames(tabId) {
+      return (await chrome.webNavigation.getAllFrames({ tabId })) ?? [];
+    },
+    sendToDocument(tabId, message, target) {
+      return chrome.tabs.sendMessage(tabId, message, target);
+    },
+    subscribeFrameNavigation(listener) {
+      const onCommitted = (details: chrome.webNavigation.WebNavigationTransitionCallbackDetails) =>
+        listener({ ...details, lifecycle: "committed" });
+      const onCompleted = (details: chrome.webNavigation.WebNavigationFramedCallbackDetails) =>
+        listener({ ...details, lifecycle: "completed" });
+      chrome.webNavigation.onCommitted.addListener(onCommitted);
+      chrome.webNavigation.onCompleted.addListener(onCompleted);
+      return () => {
+        chrome.webNavigation.onCommitted.removeListener(onCommitted);
+        chrome.webNavigation.onCompleted.removeListener(onCompleted);
+      };
+    },
+  };
+}
+
+export class RecordFrameCoordinator {
+  readonly #deps: RecordFrameCoordinatorDeps;
+  readonly #recordings = new Map<string, ArmedRecording>();
+  #attached = false;
+  #detachFrameNavigation: (() => void) | null = null;
+
+  constructor(deps: RecordFrameCoordinatorDeps = defaultDeps()) {
+    this.#deps = deps;
+  }
+
+  attach(): () => void {
+    if (this.#attached) return () => {};
+    this.#attached = true;
+    chrome.runtime.onConnect.addListener(this.#onConnect);
+    chrome.runtime.onMessage.addListener(this.#onMessage);
+    this.#detachFrameNavigation =
+      this.#deps.subscribeFrameNavigation?.(this.#onFrameNavigation) ?? null;
+    return () => {
+      if (!this.#attached) return;
+      this.#attached = false;
+      chrome.runtime.onConnect.removeListener(this.#onConnect);
+      chrome.runtime.onMessage.removeListener(this.#onMessage);
+      this.#detachFrameNavigation?.();
+      this.#detachFrameNavigation = null;
+      for (const recording of this.#recordings.values()) this.#cancelAgents(recording);
+      this.#recordings.clear();
+    };
+  }
+
+  begin(
+    requestId: string,
+    startedAtMs: number,
+    initialTabId: number,
+    onDocumentReady?: (scope: RecordingCaptureScope) => void | Promise<void>,
+  ): void {
+    const previous = this.#recordings.get(requestId);
+    if (previous) this.#cancelAgents(previous);
+    this.#recordings.set(requestId, {
+      requestId,
+      startedAtMs,
+      // Register the initial tab before navigation begins. A newly-created
+      // child document can query at document_start before armTab's frame
+      // snapshot sees it, especially when Chromium promotes it to an OOPIF.
+      tabIds: new Set([initialTabId]),
+      agents: new Map(),
+      ...(onDocumentReady ? { onDocumentReady } : {}),
+      finishing: false,
+    });
+  }
+
+  async armTab(requestId: string, tabId: number): Promise<boolean> {
+    const recording = this.#recordings.get(requestId);
+    if (!recording || recording.finishing) return false;
+    recording.tabIds.add(tabId);
+
+    let frames: BrowserFrame[];
+    try {
+      frames = await this.#deps.getAllFrames(tabId);
+    } catch {
+      frames = [{ frameId: 0 }];
+    }
+    if (!frames.some((frame) => frame.frameId === 0)) frames.unshift({ frameId: 0 });
+
+    const results = await Promise.all(
+      frames.map(async (frame) => {
+        const started = await this.#startFrame(recording, tabId, frame);
+        return { frameId: frame.frameId, started };
+      }),
+    );
+    return results.some((result) => result.frameId === 0 && result.started);
+  }
+
+  sourceFor(
+    requestId: string,
+    producerId: string,
+    sender: chrome.runtime.MessageSender,
+  ): RecordingCaptureScope | null {
+    const address = senderAddress(sender);
+    const recording = this.#recordings.get(requestId);
+    if (!address || !recording) return null;
+    const agent = recording.agents.get(documentKey(address.tabId, address.documentId));
+    if (!agent || agent.producerId !== producerId) return null;
+    return {
+      tabId: agent.tabId,
+      documentId: agent.documentId,
+      browserFrameId: agent.browserFrameId,
+      producerId: agent.producerId,
+    };
+  }
+
+  async stop(requestId: string): Promise<boolean> {
+    const recording = this.#recordings.get(requestId);
+    if (!recording) return true;
+    recording.finishing = true;
+    const commandId = crypto.randomUUID();
+    const results = await Promise.all(
+      [...recording.agents.values()].map((agent) => this.#stopAgent(agent, requestId, commandId)),
+    );
+    const succeeded = results.every(Boolean);
+    if (succeeded) this.#recordings.delete(requestId);
+    else recording.finishing = false;
+    return succeeded;
+  }
+
+  cancel(requestId: string): void {
+    const recording = this.#recordings.get(requestId);
+    if (!recording) return;
+    this.#cancelAgents(recording);
+    this.#recordings.delete(requestId);
+  }
+
+  readonly #onMessage = (
+    message: unknown,
+    sender: chrome.runtime.MessageSender,
+    sendResponse: (response: RecordFrameQueryResponse) => void,
+  ): boolean => {
+    if (!isRecordFrameQueryMessage(message)) return false;
+    const tabId = sender.tab?.id;
+    const recording =
+      typeof tabId === "number"
+        ? [...this.#recordings.values()].find(
+            (candidate) => !candidate.finishing && candidate.tabIds.has(tabId),
+          )
+        : undefined;
+    sendResponse(
+      recording
+        ? {
+            active: true,
+            requestId: recording.requestId,
+            startedAtMs: recording.startedAtMs,
+          }
+        : { active: false },
+    );
+    return false;
+  };
+
+  readonly #onFrameNavigation = (frame: BrowserFrameNavigation): void => {
+    if (frame.frameId === 0) return;
+    for (const recording of this.#recordings.values()) {
+      if (recording.finishing || !recording.tabIds.has(frame.tabId)) continue;
+      // onCommitted can race document_start, while onCompleted runs after the
+      // content script is available. Starting twice is safe and closes both
+      // the early-query and late-SPA-frame gaps.
+      void (async () => {
+        const started = await this.#startFrame(recording, frame.tabId, frame);
+        if (!started || frame.lifecycle !== "completed" || recording.finishing) return;
+        const agent = frame.documentId
+          ? recording.agents.get(documentKey(frame.tabId, frame.documentId))
+          : [...recording.agents.values()].find(
+              (candidate) =>
+                candidate.tabId === frame.tabId && candidate.browserFrameId === frame.frameId,
+            );
+        if (!agent) return;
+        await recording.onDocumentReady?.({
+          tabId: agent.tabId,
+          documentId: agent.documentId,
+          browserFrameId: agent.browserFrameId,
+          producerId: agent.producerId,
+        });
+      })();
+    }
+  };
+
+  readonly #onConnect = (port: chrome.runtime.Port): void => {
+    if (port.name !== RECORD_FRAME_PORT) return;
+    const address = senderAddress(port.sender ?? {});
+    if (!address) {
+      port.disconnect();
+      return;
+    }
+    let registered: FrameAgent | null = null;
+    port.onMessage.addListener((raw: unknown) => {
+      const message = raw as Partial<RecordFramePortMessage>;
+      if (message.type === "ready") {
+        if (typeof message.requestId !== "string" || typeof message.producerId !== "string") {
+          port.disconnect();
+          return;
+        }
+        const requestId = message.requestId;
+        const producerId = message.producerId;
+        if (registered) {
+          if (registered.requestId === requestId && registered.producerId === producerId) {
+            port.postMessage({
+              type: "ready_ack",
+              requestId,
+              producerId,
+            } satisfies RecordFramePortMessage);
+          } else {
+            port.disconnect();
+          }
+          return;
+        }
+        const recording = this.#recordings.get(requestId);
+        if (
+          !recording ||
+          recording.finishing ||
+          !recording.tabIds.has(address.tabId) ||
+          producerId.length === 0
+        ) {
+          port.disconnect();
+          return;
+        }
+        const agent: FrameAgent = {
+          ...address,
+          requestId,
+          producerId,
+          port,
+          stopWaiters: new Map(),
+        };
+        registered = agent;
+        const key = documentKey(address.tabId, address.documentId);
+        const previous = recording.agents.get(key);
+        if (previous && previous !== agent) previous.port.disconnect();
+        recording.agents.set(key, agent);
+        port.postMessage({
+          type: "ready_ack",
+          requestId,
+          producerId,
+        } satisfies RecordFramePortMessage);
+        return;
+      }
+      if (
+        message.type === "stopped" &&
+        registered &&
+        message.requestId === registered.requestId &&
+        typeof message.commandId === "string"
+      ) {
+        registered.stopWaiters.get(message.commandId)?.(message.ok === true);
+        registered.stopWaiters.delete(message.commandId);
+      }
+    });
+    port.onDisconnect.addListener(() => {
+      if (!registered) return;
+      for (const resolve of registered.stopWaiters.values()) resolve(true);
+      const recording = this.#recordings.get(registered.requestId);
+      const key = documentKey(registered.tabId, registered.documentId);
+      if (recording?.agents.get(key) === registered) recording.agents.delete(key);
+    });
+  };
+
+  #stopAgent(agent: FrameAgent, requestId: string, commandId: string): Promise<boolean> {
+    return new Promise((resolve) => {
+      const timer = setTimeout(() => {
+        agent.stopWaiters.delete(commandId);
+        resolve(false);
+      }, RECORD_FRAME_STOP_TIMEOUT_MS);
+      agent.stopWaiters.set(commandId, (ok) => {
+        clearTimeout(timer);
+        resolve(ok);
+      });
+      try {
+        agent.port.postMessage({
+          type: "stop",
+          requestId,
+          commandId,
+        } satisfies RecordFramePortMessage);
+      } catch {
+        clearTimeout(timer);
+        agent.stopWaiters.delete(commandId);
+        resolve(true);
+      }
+    });
+  }
+
+  async #startFrame(
+    recording: ArmedRecording,
+    tabId: number,
+    frame: BrowserFrame,
+  ): Promise<boolean> {
+    const message: RecordFrameStartMessage = {
+      type: RECORD_FRAME_START,
+      requestId: recording.requestId,
+      startedAtMs: recording.startedAtMs,
+    };
+    try {
+      const response = await this.#deps.sendToDocument(tabId, message, {
+        ...(frame.documentId ? { documentId: frame.documentId } : { frameId: frame.frameId }),
+      });
+      return isStarted(response);
+    } catch {
+      return false;
+    }
+  }
+
+  #cancelAgents(recording: ArmedRecording): void {
+    for (const agent of recording.agents.values()) {
+      try {
+        agent.port.postMessage({
+          type: "cancel",
+          requestId: recording.requestId,
+        } satisfies RecordFramePortMessage);
+      } catch {
+        // A destroyed Document has no remaining capture state to cancel.
+      }
+    }
+  }
+}
+
+function isStarted(value: unknown): boolean {
+  return typeof value === "object" && value !== null && (value as { ok?: unknown }).ok === true;
+}
+
+export const recordFrameCoordinator = new RecordFrameCoordinator();

apps/extension/src/lib/recording/observation-capture.ts

@@ -1,4 +1,5 @@
 import type { RenderedRef } from "@browser-skill/vom";
+import type { CdpTarget } from "@/browser-driver/frame-graph";
 import {
   type CaptureVomMatchNode,
   type CaptureVomObservationResult,
@@ -28,6 +29,11 @@ export interface RegisteredObservation {
   url: string;
 }
 
+export interface RecordingDocumentScope {
+  frameId: string;
+  target: CdpTarget;
+}
+
 function nodeKey(frameId: string, backendNodeId: number): string {
   return `${frameId}:${backendNodeId}`;
 }
@@ -40,8 +46,12 @@ export class ObservationNodeIndex {
   readonly #nodesByFrameTag = new Map<string, IndexedObservationNode[]>();
   readonly #refById = new Map<string, RenderedRef>();
   readonly #refsByFrame = new Map<string, RenderedRef[]>();
+  readonly #scopeByProducer = new Map<string, RecordingDocumentScope | null>();
 
-  constructor(input: Pick<CaptureVomObservationResult, "rootFrameId" | "matchNodes" | "refs">) {
+  constructor(
+    input: Pick<CaptureVomObservationResult, "rootFrameId" | "matchNodes" | "refs"> &
+      Partial<Pick<CaptureVomObservationResult, "frames">>,
+  ) {
     const refByNode = new Map<string, RenderedRef>();
     for (const ref of input.refs) {
       const frameId = ref.frameId ?? input.rootFrameId;
@@ -51,6 +61,16 @@ export class ObservationNodeIndex {
       frameRefs.push(ref);
       this.#refsByFrame.set(frameId, frameRefs);
     }
+    for (const frame of input.frames ?? []) {
+      const documentId = frame.recordingDocumentId;
+      if (!documentId) continue;
+      this.#scopeByProducer.set(
+        documentId,
+        this.#scopeByProducer.has(documentId)
+          ? null
+          : { frameId: frame.frameId, target: frame.target },
+      );
+    }
     for (const geometry of input.matchNodes) {
       const { frameId } = geometry;
       const entry = {
@@ -76,6 +96,10 @@ export class ObservationNodeIndex {
   refs(frameId: string): readonly RenderedRef[] {
     return this.#refsByFrame.get(frameId) ?? [];
   }
+
+  documentScope(producerId: string): RecordingDocumentScope | undefined {
+    return this.#scopeByProducer.get(producerId) ?? undefined;
+  }
 }
 
 async function readTabMeta(

apps/extension/src/lib/recording/observation-session.ts

@@ -28,7 +28,13 @@ function abortableDelay(ms: number, signal?: AbortSignal): Promise<void> {
 }
 
 function isTargeted(draft: RecordingDraftStep): draft is TargetedRecordingDraft {
-  return draft.op !== "navigate" && draft.op !== "scroll";
+  return (
+    draft.op === "click" ||
+    draft.op === "hover" ||
+    draft.op === "fill" ||
+    draft.op === "press" ||
+    draft.op === "select"
+  );
 }
 
 export class RecordingObservationSession {

apps/extension/src/lib/recording/recording-runtime.ts

@@ -1,6 +1,7 @@
 import type { CdpRunner, ChromeTabsApi } from "@/tools/shared";
 import type { StopReason, TraceV3 } from "@/transport/types";
-import type { DocumentSettleScope } from "./document-settle";
+import { type DocumentSettleScope, waitForDocumentSettled } from "./document-settle";
+import type { RegisteredObservation } from "./observation-capture";
 import { RecordingObservationSession } from "./observation-session";
 import { inferMissingPostStates, SettleController } from "./settle-controller";
 import { RecordingStateRegistry } from "./state-registry";
@@ -10,11 +11,13 @@ import type { RecordingDraftStep, StepAnnotation } from "./types";
 interface TabRecordingContext {
   session: RecordingObservationSession;
   settle: SettleController;
-  initialCapture: PendingInitialCapture | null;
+  pendingCapture: PendingCapture | null;
+  frameRefresh: Promise<void>;
+  frameRefreshAbort: AbortController | null;
 }
 
-interface PendingInitialCapture {
-  promise: Promise<void>;
+interface PendingCapture {
+  promise: Promise<RegisteredObservation>;
   abort: AbortController;
 }
 
@@ -56,37 +59,113 @@ export class RecordingObservationRuntime {
         tabsApi: this.#tabsApi,
         tabId,
       }),
-      initialCapture: null,
+      pendingCapture: null,
+      frameRefresh: Promise.resolve(),
+      frameRefreshAbort: null,
     };
     this.#contexts.set(tabId, context);
     return context;
   }
 
-  async captureInitial(tabId: number): Promise<void> {
+  async #capture(tabId: number): Promise<RegisteredObservation> {
     const context = this.#context(tabId);
-    if (context.session.cursor.lastSettled) return;
-    if (context.initialCapture) return context.initialCapture.promise;
+    if (context.pendingCapture) return context.pendingCapture.promise;
 
     const abort = new AbortController();
-    let pending!: PendingInitialCapture;
+    let pending!: PendingCapture;
     const promise = context.session.capture(this.#cdp, this.#tabsApi, tabId, abort.signal);
     pending = {
       abort,
-      promise: promise
-        .then(() => {})
-        .finally(() => {
-          if (context.initialCapture === pending) context.initialCapture = null;
-        }),
+      promise: promise.finally(() => {
+        if (context.pendingCapture === pending) context.pendingCapture = null;
+      }),
     };
-    context.initialCapture = pending;
+    context.pendingCapture = pending;
     return pending.promise;
   }
 
+  async captureInitial(tabId: number): Promise<void> {
+    const context = this.#context(tabId);
+    if (context.session.cursor.lastSettled) return;
+    await this.#capture(tabId);
+  }
+
+  /** Refresh the safe observation after a late child Document becomes usable. */
+  async refreshDocument(tabId: number, producerId: string): Promise<void> {
+    const context = this.#context(tabId);
+    context.frameRefreshAbort?.abort();
+    const abort = new AbortController();
+    context.frameRefreshAbort = abort;
+    const previous = context.frameRefresh;
+    const refresh = (async () => {
+      await previous;
+      if (abort.signal.aborted) return;
+      if (context.pendingCapture) await Promise.allSettled([context.pendingCapture.promise]);
+      if (abort.signal.aborted) return;
+
+      // The first capture discovers the safe producer -> CDP Document scope.
+      await this.#capture(tabId);
+      if (abort.signal.aborted) return;
+      const scope = context.session.cursor.lastSettled?.index.documentScope(producerId);
+      if (scope) {
+        await waitForDocumentSettled(this.#cdp, scope, { signal: abort.signal });
+      }
+      if (abort.signal.aborted) return;
+
+      // Capture again after the child SPA is quiet so the next action can be
+      // matched against refs that actually exist in its pre-action state.
+      await this.#capture(tabId);
+    })();
+    const tracked = refresh.catch(() => {});
+    context.frameRefresh = tracked;
+    try {
+      await refresh;
+    } finally {
+      if (context.frameRefresh === tracked) context.frameRefreshAbort = null;
+    }
+  }
+
+  async captureTabTransition(
+    fromTabId: number,
+    toTabId: number,
+  ): Promise<{ preStateId?: string; postStateId?: string; targetUrl?: string }> {
+    const from = this.#context(fromTabId);
+    await this.#flushContext(from);
+    if (!from.session.cursor.lastSettled) {
+      try {
+        await this.captureInitial(fromTabId);
+      } catch {
+        // A target-tab observation can still preserve the forward transition.
+      }
+    }
+
+    const to = this.#context(toTabId);
+    let target = to.session.cursor.lastSettled;
+    try {
+      target = await this.#capture(toTabId);
+    } catch {
+      // Reuse the last settled target state when a refresh races navigation.
+    }
+
+    const source = from.session.cursor.lastSettled;
+    return {
+      ...(source ? { preStateId: source.stateId } : {}),
+      ...(target ? { postStateId: target.stateId, targetUrl: target.url } : {}),
+    };
+  }
+
+  bindTabTransition(
+    draft: Extract<RecordingDraftStep, { op: "switch_tab" }>,
+    draftId: number,
+  ): void {
+    if (draft.preStateId) this.#registry.markStep(draft.preStateId, draftId);
+  }
+
   async processDraft(
     tabId: number,
     drafts: RecordingDraftStep[],
     draftIndex: number,
-    scope?: DocumentSettleScope,
+    producerId?: string,
   ): Promise<void> {
     const draft = drafts[draftIndex];
     if (!draft) return;
@@ -98,6 +177,23 @@ export class RecordingObservationRuntime {
         // Post-action settle can still provide a usable state.
       }
     }
+    const scope = producerId
+      ? context.session.cursor.lastSettled?.index.documentScope(producerId)
+      : undefined;
+    if (
+      producerId &&
+      (draft.op === "click" ||
+        draft.op === "hover" ||
+        draft.op === "fill" ||
+        draft.op === "press" ||
+        draft.op === "select")
+    ) {
+      draft.targetHint = {
+        ...(draft.targetHint ?? {}),
+        frameId: scope?.frameId ?? null,
+        geometrySpace: "local",
+      };
+    }
     context.session.bindDraft(draft, draftIndex + 1, context.settle.hasPending);
     context.settle.schedule(drafts, draftIndex, scope);
   }
@@ -119,23 +215,24 @@ export class RecordingObservationRuntime {
     this.#context(tabId).settle.scheduleRedirect(drafts, url);
   }
 
-  async flushRedirects(): Promise<void> {
-    for (const context of this.#contexts.values()) await context.settle.flushRedirects();
+  async #flushContext(context: TabRecordingContext): Promise<void> {
+    await context.frameRefresh;
+    if (context.pendingCapture) await Promise.allSettled([context.pendingCapture.promise]);
+    await context.settle.flushRedirects();
+    await context.settle.flush();
+  }
+
+  async flushRedirects(tabId: number): Promise<void> {
+    await this.#contexts.get(tabId)?.settle.flushRedirects();
   }
 
   async flush(): Promise<void> {
-    await Promise.allSettled(
-      [...this.#contexts.values()].flatMap((context) =>
-        context.initialCapture ? [context.initialCapture.promise] : [],
-      ),
-    );
-    await this.flushRedirects();
-    for (const context of this.#contexts.values()) await context.settle.flush();
+    for (const context of this.#contexts.values()) await this.#flushContext(context);
   }
 
   async settleTrailing(tabId: number, drafts: RecordingDraftStep[]): Promise<void> {
     const context = this.#context(tabId);
-    if (context.initialCapture) await Promise.allSettled([context.initialCapture.promise]);
+    if (context.pendingCapture) await Promise.allSettled([context.pendingCapture.promise]);
     if (!context.session.cursor.lastSettled) {
       try {
         await this.captureInitial(tabId);
@@ -149,7 +246,8 @@ export class RecordingObservationRuntime {
 
   cancel(): void {
     for (const context of this.#contexts.values()) {
-      context.initialCapture?.abort.abort();
+      context.frameRefreshAbort?.abort();
+      context.pendingCapture?.abort.abort();
       context.settle.cancel();
     }
   }
@@ -161,6 +259,7 @@ export class RecordingObservationRuntime {
     startUrl?: string;
     stoppedBy: StopReason;
     bskVersion: string;
+    includeTabSwitches?: boolean;
   }): TraceV3 {
     return buildTraceV3({
       registry: this.#registry,
@@ -172,6 +271,7 @@ export class RecordingObservationRuntime {
       stoppedBy: input.stoppedBy,
       bskVersion: input.bskVersion,
       redactValues: this.#redactValues,
+      includeTabSwitches: input.includeTabSwitches,
     });
   }
 }

apps/extension/src/lib/recording/step-buffer.ts

@@ -4,6 +4,10 @@ import type { RecordingDraftStep, TargetMatchHint } from "./types";
 
 export interface RecordingStepBuffer {
   steps: RecordingDraftStep[];
+  navigation: RecordingNavigationCursor;
+}
+
+export interface RecordingNavigationCursor {
   currentUrl?: string;
   pendingNavigation: boolean;
   pendingNavigationDeadline?: number;
@@ -87,22 +91,23 @@ export function observeRecordedNavigation(
   transitionType?: string,
   transitionQualifiers?: string[],
 ): NavigationObserveResult {
-  if (!url || url === buffer.currentUrl) return { kind: "noop" };
-  buffer.currentUrl = url;
+  const navigation = buffer.navigation;
+  if (!url || url === navigation.currentUrl) return { kind: "noop" };
+  navigation.currentUrl = url;
 
   const pendingIsCurrent =
-    buffer.pendingNavigation &&
-    (buffer.pendingNavigationDeadline === undefined ||
-      buffer.pendingNavigationDeadline >= Date.now());
+    navigation.pendingNavigation &&
+    (navigation.pendingNavigationDeadline === undefined ||
+      navigation.pendingNavigationDeadline >= Date.now());
 
   if (causedByAction === true || (causedByAction === undefined && pendingIsCurrent)) {
-    buffer.pendingNavigation = false;
-    buffer.pendingNavigationDeadline = undefined;
+    navigation.pendingNavigation = false;
+    navigation.pendingNavigationDeadline = undefined;
     const annotatedIndex = annotateLastStepNavigation(buffer, url);
     if (annotatedIndex >= 0) return { kind: "annotated", index: annotatedIndex };
   } else {
-    buffer.pendingNavigation = false;
-    buffer.pendingNavigationDeadline = undefined;
+    navigation.pendingNavigation = false;
+    navigation.pendingNavigationDeadline = undefined;
   }
 
   if (hasRedirectQualifier(transitionQualifiers)) {
@@ -135,14 +140,14 @@ export function appendRecordedPayload(
     return result.kind === "appended" ? result.index : null;
   }
   const step = toDraftStep(
-    { ...payload, page_url: payload.page_url ?? buffer.currentUrl },
+    { ...payload, page_url: payload.page_url ?? buffer.navigation.currentUrl },
     targetHint,
   );
   if (!step) return null;
   buffer.steps.push(step);
   if (step.op === "click" || step.op === "press" || step.op === "select" || step.op === "fill") {
-    buffer.pendingNavigation = payload.expects_navigation === true;
-    buffer.pendingNavigationDeadline = buffer.pendingNavigation
+    buffer.navigation.pendingNavigation = payload.expects_navigation === true;
+    buffer.navigation.pendingNavigationDeadline = buffer.navigation.pendingNavigation
       ? Date.now() + NAVIGATION_TRIGGER_WINDOW_MS
       : undefined;
   }

apps/extension/src/lib/recording/tab-coordinator.ts

@@ -0,0 +1,61 @@
+import type { RecordingNavigationCursor } from "./step-buffer";
+
+export interface TabActivation {
+  tabId: number;
+  revision: number;
+}
+
+export class RecordingTabCoordinator {
+  readonly #navigationByTab = new Map<number, RecordingNavigationCursor>();
+  #activeTabId: number;
+  #currentTabId: number;
+  #activationRevision = 0;
+
+  constructor(initialTabId: number, initialUrl?: string) {
+    this.#activeTabId = initialTabId;
+    this.#currentTabId = initialTabId;
+    this.#navigationByTab.set(initialTabId, {
+      currentUrl: initialUrl,
+      pendingNavigation: false,
+    });
+  }
+
+  get activeTabId(): number {
+    return this.#activeTabId;
+  }
+
+  get currentTabId(): number {
+    return this.#currentTabId;
+  }
+
+  noteActivation(tabId: number): TabActivation {
+    this.#activeTabId = tabId;
+    this.#activationRevision += 1;
+    return { tabId, revision: this.#activationRevision };
+  }
+
+  isLatest(activation: TabActivation): boolean {
+    return (
+      activation.tabId === this.#activeTabId && activation.revision === this.#activationRevision
+    );
+  }
+
+  commit(tabId: number, currentUrl?: string): void {
+    if (currentUrl !== undefined) this.navigation(tabId).currentUrl = currentUrl;
+    this.#currentTabId = tabId;
+  }
+
+  navigation(tabId: number, fallbackUrl?: string): RecordingNavigationCursor {
+    const existing = this.#navigationByTab.get(tabId);
+    if (existing) {
+      if (!existing.currentUrl && fallbackUrl) existing.currentUrl = fallbackUrl;
+      return existing;
+    }
+    const created: RecordingNavigationCursor = {
+      currentUrl: fallbackUrl,
+      pendingNavigation: false,
+    };
+    this.#navigationByTab.set(tabId, created);
+    return created;
+  }
+}

apps/extension/src/lib/recording/target-matcher.ts

@@ -14,8 +14,13 @@ function rectMatches(a: TargetGeometry["rect"], b: TargetGeometry["rect"]): bool
   return close(a.x, b.x) && close(a.y, b.y) && close(a.w, b.w) && close(a.h, b.h);
 }
 
-function candidateMatches(candidate: IndexedObservationNode, geometry: TargetGeometry): boolean {
-  return candidate.geometry.rect !== null && rectMatches(geometry.rect, candidate.geometry.rect);
+function candidateMatches(
+  candidate: IndexedObservationNode,
+  geometry: TargetGeometry,
+  geometrySpace: "top" | "local",
+): boolean {
+  const rect = geometrySpace === "local" ? candidate.geometry.localRect : candidate.geometry.rect;
+  return rect != null && rectMatches(geometry.rect, rect);
 }
 
 export function unmatchedTarget(fallback?: CaptureTargetDescriptor): TargetDescriptorV3 {
@@ -53,12 +58,17 @@ export function matchObservationTarget(input: {
   hint?: TargetMatchHint;
   fallback?: CaptureTargetDescriptor;
 }): TargetDescriptorV3 {
+  if (input.hint?.frameId === null) return unmatchedTarget(input.fallback);
   const frameId = input.hint?.frameId ?? input.observation.rootFrameId;
   const geometry = input.hint?.geometry;
   if (geometry) {
     const matches = input.observation.index
       .candidates(frameId, geometry.tag)
-      .filter((candidate) => candidate.ref && candidateMatches(candidate, geometry));
+      .filter(
+        (candidate) =>
+          candidate.ref &&
+          candidateMatches(candidate, geometry, input.hint?.geometrySpace ?? "top"),
+      );
     if (matches.length === 1) return descriptor(matches[0]!.ref!);
     const semanticMatches = matches.filter(
       (candidate) => candidate.ref && matchesSemantics(candidate.ref, input.fallback),

apps/extension/src/lib/recording/trace-builder-v3.ts

@@ -40,8 +40,12 @@ export function buildTraceV3(input: {
   stoppedBy: StopReason;
   bskVersion: string;
   redactValues?: boolean;
+  includeTabSwitches?: boolean;
 }): TraceV3 {
-  const reduced = reduceTraceStepsV3(input.drafts, { redactValues: input.redactValues });
+  const reduced = reduceTraceStepsV3(input.drafts, {
+    includeTabSwitches: input.includeTabSwitches,
+    redactValues: input.redactValues,
+  });
   const entries = publishedEntries(input.registry, reduced.steps);
   const publishedId = new Map(entries.map((entry, index) => [entry.id, `s${index + 1}`]));
   const annotationsByState = new Map<string, StepAnnotation[]>();

apps/extension/src/lib/recording/trace-reducer-v2.ts

@@ -119,14 +119,6 @@ function toV2Step(
         },
         effectForNavigation(step.navigatedTo, urlToId),
       );
-    case "hover":
-      if (!step.captureTarget) return null;
-      return {
-        op: "hover",
-        id,
-        page,
-        target: step.captureTarget,
-      };
     case "fill":
       if (!step.captureTarget) return null;
       return {
@@ -161,7 +153,11 @@ function toV2Step(
         },
         effectForNavigation(step.navigatedTo, urlToId),
       );
+    // `hover` only exists in Trace v3. Peers that negotiate v2 predate the
+    // step variant and fail to decode the whole result if we emit it.
+    case "hover":
     case "scroll":
+    case "switch_tab":
       return null;
   }
 }

apps/extension/src/lib/recording/trace-reducer-v3.ts

@@ -58,8 +58,26 @@ function selection(values: string[], labels?: string[]): Array<{ value: string;
   }));
 }
 
-function reduceDraft(draft: RecordingDraftStep, id: number, redactValues: boolean): StepV3 | null {
+interface ReduceDraftOptions {
+  includeTabSwitches: boolean;
+  redactValues: boolean;
+}
+
+function reduceDraft(
+  draft: RecordingDraftStep,
+  id: number,
+  options: ReduceDraftOptions,
+): StepV3 | null {
   if (!shouldIncludeDraft(draft)) return null;
+  if (draft.op === "switch_tab") {
+    if (!options.includeTabSwitches || !draft.preStateId || !draft.postStateId) return null;
+    return {
+      op: "switch_tab",
+      id,
+      state: draft.preStateId,
+      result: { state: draft.postStateId },
+    };
+  }
   const state = draft.preStateId ?? draft.postStateId;
   const resultState = draft.postStateId ?? draft.preStateId;
   if (!state || !resultState) return null;
@@ -81,7 +99,7 @@ function reduceDraft(draft: RecordingDraftStep, id: number, redactValues: boolea
         target: draft.matchedTarget ?? unmatchedTarget(draft.captureTarget),
       };
     case "fill":
-      const fillIsRedacted = redactValues || draft.redacted === true;
+      const fillIsRedacted = options.redactValues || draft.redacted === true;
       return {
         op: "fill",
         ...common,
@@ -105,7 +123,7 @@ function reduceDraft(draft: RecordingDraftStep, id: number, redactValues: boolea
         op: "select",
         ...common,
         target: draft.matchedTarget ?? unmatchedTarget(draft.captureTarget),
-        ...(!redactValues ? { selection: selection(draft.values, draft.labels) } : {}),
+        ...(!options.redactValues ? { selection: selection(draft.values, draft.labels) } : {}),
       };
     case "scroll":
       return { op: "scroll", ...common };
@@ -119,12 +137,15 @@ export interface ReducedTraceV3 {
 
 export function reduceTraceStepsV3(
   steps: RecordingDraftStep[],
-  options: { redactValues?: boolean } = {},
+  options: { includeTabSwitches?: boolean; redactValues?: boolean } = {},
 ): ReducedTraceV3 {
   const output: StepV3[] = [];
   const stepIdByDraftId = new Map<number, number>();
   for (const { draft, draftIds } of collapseRedirects(steps)) {
-    const step = reduceDraft(draft, output.length + 1, options.redactValues ?? false);
+    const step = reduceDraft(draft, output.length + 1, {
+      includeTabSwitches: options.includeTabSwitches === true,
+      redactValues: options.redactValues === true,
+    });
     if (!step) continue;
     output.push(step);
     for (const draftId of draftIds) stepIdByDraftId.set(draftId, step.id);

apps/extension/src/lib/recording/types.ts

@@ -15,8 +15,9 @@ export interface TargetGeometry {
 
 export interface TargetMatchHint {
   geometry?: TargetGeometry;
-  /** Missing means the current top frame, never an unrestricted frame search. */
-  frameId?: string;
+  /** Missing means top frame; null means the source Document could not be resolved. */
+  frameId?: string | null;
+  geometrySpace?: "top" | "local";
 }
 
 export interface StepAnnotation {
@@ -69,6 +70,7 @@ export type RecordingDraftStep =
       DraftTarget &
       DraftNavigationEffect)
   | ({ op: "scroll" } & DraftStateLink)
+  | ({ op: "switch_tab" } & DraftStateLink)
   | ({
       op: "navigate";
       url: string;

apps/extension/src/session-manager/__tests__/ref-store.test.ts

@@ -13,6 +13,8 @@ describe("RefStore", () => {
       backendNodeId: 42,
       tabId: 7,
       generation: 0,
+      kind: "dom",
+      capabilities: ["interact", "screenshot"],
     });
     expect(s.size()).toBe(1);
     expect(s.isEmpty()).toBe(false);
@@ -48,4 +50,31 @@ describe("RefStore", () => {
       cdpSessionId: "child-session",
     });
   });
+
+  it("preserves explicit capabilities for visual surface refs", () => {
+    const s = new RefStore();
+    s.set("e1", 42, {
+      tabId: 7,
+      kind: "surface",
+      capabilities: ["screenshot"],
+    });
+
+    expect(s.resolveEntry("e1")).toMatchObject({
+      kind: "surface",
+      capabilities: ["screenshot"],
+    });
+  });
+
+  it("never grants ordinary interaction to a surface through defaults or caller input", () => {
+    const s = new RefStore();
+    s.set("e1", 42, { tabId: 7, kind: "surface" });
+    s.set("e2", 43, {
+      tabId: 7,
+      kind: "surface",
+      capabilities: ["interact", "screenshot"],
+    });
+
+    expect(s.resolveEntry("e1")?.capabilities).toEqual(["screenshot"]);
+    expect(s.resolveEntry("e2")?.capabilities).toEqual(["screenshot"]);
+  });
 });

apps/extension/src/session-manager/ref-store.ts

@@ -1,3 +1,5 @@
+import type { Rect } from "@browser-skill/vom";
+
 /**
  * Per-session map from `@e<N>` snapshot refs to a CDP node address.
  *
@@ -12,12 +14,17 @@
  * inside the `SessionContext`.
  */
 export type BackendNodeId = number;
+export type RefCapability = "interact" | "screenshot";
+export type RefTargetKind = "dom" | "surface";
 
 export interface RefEntry {
   backendNodeId: BackendNodeId;
   tabId: number | null;
   frameId?: string;
   cdpSessionId?: string;
+  visibleRect?: Rect;
+  kind: RefTargetKind;
+  capabilities: RefCapability[];
   generation: number;
 }
 
@@ -28,8 +35,19 @@ export type RefInput =
       tabId: number;
       frameId?: string;
       cdpSessionId?: string;
+      visibleRect?: Rect;
+      kind?: RefTargetKind;
+      capabilities?: RefCapability[];
     };
 
+function capabilitiesFor(
+  kind: RefTargetKind,
+  capabilities: RefCapability[] | undefined,
+): RefCapability[] {
+  if (kind === "surface") return ["screenshot"];
+  return capabilities ?? ["interact", "screenshot"];
+}
+
 export class RefStore {
   private readonly map = new Map<string, RefEntry>();
   private generation = 0;
@@ -70,13 +88,20 @@ export class RefStore {
       tabId?: number;
       frameId?: string;
       cdpSessionId?: string;
+      visibleRect?: Rect;
+      kind?: RefTargetKind;
+      capabilities?: RefCapability[];
     } = {},
   ): void {
+    const kind = opts.kind ?? "dom";
     this.map.set(normaliseRef(ref), {
       backendNodeId: id,
       tabId: opts.tabId ?? null,
       ...(opts.frameId ? { frameId: opts.frameId } : {}),
       ...(opts.cdpSessionId ? { cdpSessionId: opts.cdpSessionId } : {}),
+      ...(opts.visibleRect ? { visibleRect: opts.visibleRect } : {}),
+      kind,
+      capabilities: capabilitiesFor(kind, opts.capabilities),
       generation: this.generation,
     });
   }
@@ -94,14 +119,20 @@ export class RefStore {
       return {
         backendNodeId: input,
         tabId: null,
+        kind: "dom",
+        capabilities: ["interact", "screenshot"],
         generation: this.generation,
       };
     }
+    const kind = input.kind ?? "dom";
     return {
       backendNodeId: input.backendNodeId,
       tabId: input.tabId,
       ...(input.frameId ? { frameId: input.frameId } : {}),
       ...(input.cdpSessionId ? { cdpSessionId: input.cdpSessionId } : {}),
+      ...(input.visibleRect ? { visibleRect: input.visibleRect } : {}),
+      kind,
+      capabilities: capabilitiesFor(kind, input.capabilities),
       generation: this.generation,
     };
   }

apps/extension/src/shared/recording-document-identity.ts

@@ -0,0 +1,22 @@
+export const RECORD_DOCUMENT_ATTRIBUTE = "data-bsk-record-document";
+
+const RECORDING_DOCUMENT_ID_PATTERN =
+  /^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i;
+const RECORDING_DOCUMENT_MARKER_PREFIX = "bsk:";
+
+export function recordingDocumentMarkerValue(identity: string): string {
+  if (!RECORDING_DOCUMENT_ID_PATTERN.test(identity)) {
+    throw new TypeError("recording Document identity must be a random UUID");
+  }
+  return `${RECORDING_DOCUMENT_MARKER_PREFIX}${identity}`;
+}
+
+/** Read BrowserSkill's opaque per-Document recording identity from captured attributes. */
+export function readRecordingDocumentIdentity(
+  attrs: Readonly<Record<string, string>>,
+): string | undefined {
+  const marker = attrs[RECORD_DOCUMENT_ATTRIBUTE];
+  if (!marker?.startsWith(RECORDING_DOCUMENT_MARKER_PREFIX)) return undefined;
+  const identity = marker.slice(RECORDING_DOCUMENT_MARKER_PREFIX.length);
+  return identity && RECORDING_DOCUMENT_ID_PATTERN.test(identity) ? identity : undefined;
+}

apps/extension/src/tools/__tests__/dispatcher.test.ts

@@ -8,6 +8,7 @@ import type {
   RequestFrame,
 } from "@/transport/types";
 import { ToolDispatcher } from "../dispatcher";
+import { resetBrowserObservationForTests, setBrowserObservationAttachForTests } from "../record";
 
 type TestDispatcherCdp = NonNullable<ConstructorParameters<typeof ToolDispatcher>[0]["cdp"]>;
 
@@ -44,9 +45,72 @@ function makeRequest(method: string, params: unknown): RequestFrame {
 
 describe("ToolDispatcher", () => {
   afterEach(() => {
+    resetBrowserObservationForTests();
     vi.unstubAllGlobals();
   });
 
+  it("uses the configured recording runtime for start and stop", async () => {
+    const { transport, sent, deliver } = fakeTransport();
+    const sessions = new SessionManager({
+      agentWindow: {
+        create: vi.fn(async () => 4242),
+        remove: vi.fn(),
+        ensureActiveTab: vi.fn(async () => {}),
+      },
+    });
+    await sessions.start("aa11");
+    const tab = {
+      id: 7,
+      windowId: 4242,
+      active: true,
+      status: "complete",
+      url: "https://example.com/start",
+    } as chrome.tabs.Tab;
+    const frameCoordinator = {
+      begin: vi.fn(),
+      armTab: vi.fn(async () => true),
+      sourceFor: vi.fn(() => null),
+      stop: vi.fn(async () => true),
+      cancel: vi.fn(),
+    };
+    const sendToTab = vi.fn(async () => ({ ok: true }));
+    setBrowserObservationAttachForTests(
+      () => () => {},
+      () => () => {},
+    );
+    const dispatcher = new ToolDispatcher({
+      transport,
+      sessions,
+      recording: {
+        tabsApi: {
+          get: vi.fn(async () => tab),
+          query: vi.fn(async () => [tab]),
+        },
+        frameCoordinator,
+        sendToTab,
+      },
+    });
+    dispatcher.start();
+
+    deliver(
+      makeRequest("tool.record_start", {
+        session_id: "aa11",
+        url: "https://example.com/start",
+      }),
+    );
+    await vi.waitFor(() => expect(sent).toHaveLength(1));
+
+    expect(sent[0]).toMatchObject({ result: { tab_id: 7, recording: true } });
+    expect(frameCoordinator.begin).toHaveBeenCalledOnce();
+    expect(frameCoordinator.armTab).toHaveBeenCalledWith(expect.any(String), 7);
+
+    deliver({ id: "r-2", method: "tool.record_stop", params: { session_id: "aa11" } });
+    await vi.waitFor(() => expect(sent).toHaveLength(2));
+
+    expect(frameCoordinator.stop).toHaveBeenCalledOnce();
+    expect(sent[1]).toMatchObject({ id: "r-2", result: { trace: { steps: [] } } });
+  });
+
   it("routes tool.session_start to the SessionManager and replies with the window id", async () => {
     const { transport, sent, deliver } = fakeTransport();
     const sessions = new SessionManager({

apps/extension/src/tools/__tests__/interaction.test.ts

@@ -123,6 +123,29 @@ describe("handleClick", () => {
     expect(fake.cdp.send).not.toHaveBeenCalled();
   });
 
+  it("rejects screenshot-only visual surface refs before issuing CDP calls", async () => {
+    const sm = new SessionManager({ agentWindow: fakeAgentWindow([100]) });
+    const ctx = await sm.start("aa11");
+    ctx.refStore.set("e3", 1234, {
+      tabId: 4,
+      kind: "surface",
+      capabilities: ["screenshot"],
+    });
+    const fake = makeFakeCdp({});
+
+    const res = await handleClick(
+      sm,
+      { session_id: "aa11", ref: "@e3" },
+      { cdp: fake.cdp, tabsApi: fake.tabsApi },
+    );
+
+    expect(res).toMatchObject({
+      code: "permission_denied",
+      data: { reason: "ref_capability_denied", required_capability: "interact" },
+    });
+    expect(fake.cdp.send).not.toHaveBeenCalled();
+  });
+
   it("clicks by ref, computes the quad centre, dispatches three mouse events", async () => {
     const sm = new SessionManager({ agentWindow: fakeAgentWindow([100]) });
     const ctx = await sm.start("aa11");

apps/extension/src/tools/__tests__/observation.test.ts

@@ -300,6 +300,76 @@ describe("handleScreenshot", () => {
     expect(clip).toMatchObject({ x: 10, y: 20, width: 100, height: 40 });
   });
 
+  it("captures a bounded visible crop for a visual surface without scrolling it", async () => {
+    const sm = new SessionManager({ agentWindow: fakeAgentWindow([100]) });
+    const ctx = await sm.start("aa11");
+    ctx.refStore.set("e5", 999, {
+      tabId: 7,
+      kind: "surface",
+      capabilities: ["screenshot"],
+    });
+    const { cdp, sent } = makeFakeCdp({
+      "Page.getLayoutMetrics": () => ({
+        cssLayoutViewport: { clientWidth: 4096, clientHeight: 4096 },
+      }),
+      "DOM.getContentQuads": () => ({ quads: [[0, 0, 4096, 0, 4096, 4096, 0, 4096]] }),
+      "Page.captureScreenshot": () => ({ data: TINY_PNG }),
+    });
+
+    const res = await handleScreenshot(
+      sm,
+      { session_id: "aa11", ref: "@e5", tab_id: 7 },
+      makeScreenshotDeps({
+        cdp,
+        get: vi.fn(async () => ({ id: 7, windowId: 100, active: false }) as chrome.tabs.Tab),
+        query: vi.fn(),
+        captureVisibleTab: vi.fn(),
+      }),
+    );
+
+    if ("code" in res) throw new Error(`unexpected error: ${JSON.stringify(res)}`);
+    expect(sent.some((call) => call.method === "DOM.scrollIntoViewIfNeeded")).toBe(false);
+    const clip = sent.find((call) => call.method === "Page.captureScreenshot")?.params as {
+      clip?: { width: number; height: number; scale: number };
+    };
+    expect(clip.clip).toMatchObject({ width: 4096, height: 4096 });
+    expect(clip.clip?.scale).toBeCloseTo(Math.sqrt(4_000_000 / (4096 * 4096)));
+  });
+
+  it("crops a visual surface screenshot to its observation-time visible region", async () => {
+    const sm = new SessionManager({ agentWindow: fakeAgentWindow([100]) });
+    const ctx = await sm.start("aa11");
+    ctx.refStore.set("e5", 999, {
+      tabId: 7,
+      kind: "surface",
+      visibleRect: { x: 25, y: 30, w: 50, h: 40 },
+    });
+    const { cdp, sent } = makeFakeCdp({
+      "Page.getLayoutMetrics": () => ({
+        cssLayoutViewport: { clientWidth: 800, clientHeight: 600 },
+      }),
+      "DOM.getContentQuads": () => ({ quads: [[0, 0, 200, 0, 200, 100, 0, 100]] }),
+      "Page.captureScreenshot": () => ({ data: TINY_PNG }),
+    });
+
+    const res = await handleScreenshot(
+      sm,
+      { session_id: "aa11", ref: "@e5", tab_id: 7 },
+      makeScreenshotDeps({
+        cdp,
+        get: vi.fn(async () => ({ id: 7, windowId: 100, active: false }) as chrome.tabs.Tab),
+        query: vi.fn(),
+        captureVisibleTab: vi.fn(),
+      }),
+    );
+
+    if ("code" in res) throw new Error(`unexpected error: ${JSON.stringify(res)}`);
+    const clip = sent.find((call) => call.method === "Page.captureScreenshot")?.params as {
+      clip?: { x: number; y: number; width: number; height: number };
+    };
+    expect(clip.clip).toMatchObject({ x: 25, y: 30, width: 50, height: 40 });
+  });
+
   it("returns not_found for unknown ref", async () => {
     const sm = new SessionManager({ agentWindow: fakeAgentWindow([100]) });
     await sm.start("aa11");
@@ -1656,7 +1726,7 @@ describe("buildVomScene", () => {
 
     const scene = buildVomScene(axNodes, captured);
     expect(scene.nodes.find((n) => n.id === 20)).toEqual(
-      expect.objectContaining({ id: 20, role: "generic", cursor: "pointer" }),
+      expect.objectContaining({ id: 20, role: "button", name: "close", cursor: "pointer" }),
     );
     const rendered = renderVom(scene);
     expect(rendered.text).toContain('@e1 button "close"');
@@ -1732,7 +1802,7 @@ describe("buildVomScene", () => {
     };
 
     const scene = buildVomScene(axNodes, captured);
-    expect(scene.nodes.find((n) => n.id === 20)?.role).toBe("generic");
+    expect(scene.nodes.find((n) => n.id === 20)).toBeUndefined();
     expect(scene.nodes.find((n) => n.id === 30)?.role).toBe("link");
   });
 
@@ -1801,9 +1871,9 @@ describe("buildVomScene", () => {
 
     const scene = buildVomScene(axNodes, captured);
     expect(scene.nodes.find((n) => n.id === 20)).toEqual(
-      expect.objectContaining({ id: 20, role: "generic", attrs: { "aria-label": "收藏" } }),
+      expect.objectContaining({ id: 20, role: "button", attrs: { "aria-label": "收藏" } }),
     );
-    expect(scene.nodes.find((n) => n.id === 30)?.role).toBe("generic");
+    expect(scene.nodes.find((n) => n.id === 30)).toBeUndefined();
     const rendered = renderVom(scene);
     expect(rendered.text).toContain('@e1 button "收藏"');
     expect(rendered.refs.map(({ ref, backendNodeId }) => ({ ref, backendNodeId }))).toEqual([
@@ -2131,7 +2201,7 @@ describe("buildVomScene", () => {
     });
 
     expect(scene.surfaces).toEqual([
-      { triggerId: 21, triggerAction: "hover", subItems: ["My profile", "Sign out"] },
+      { triggerId: 20, triggerAction: "hover", subItems: ["My profile", "Sign out"] },
     ]);
     expect(renderVom(scene).text).toContain(
       '@e1 button "image" [hover first: My profile | Sign out]',
@@ -2693,6 +2763,85 @@ describe("handleSnapshot", () => {
     );
   });
 
+  it("discovers rendered canvases only in observe and stores a screenshot-only ref", async () => {
+    const sm = new SessionManager({ agentWindow: fakeAgentWindow([100]) });
+    const ctx = await sm.start("aa11");
+    const root: CdpAxNode = {
+      nodeId: "1",
+      role: { type: "role", value: "RootWebArea" },
+      name: { type: "computedString", value: "Canvas app" },
+      backendDOMNodeId: 100,
+    };
+    const strings = ["body", "canvas", "static", "auto"];
+    const i = (value: string) => strings.indexOf(value);
+    const send = vi.fn(async (_tabId: number, method: string) => {
+      if (method === "Accessibility.enable" || method === "DOMSnapshot.enable") return {};
+      if (method === "Accessibility.getFullAXTree") return { nodes: [root] };
+      if (method === "Page.getLayoutMetrics") {
+        return { cssLayoutViewport: { clientWidth: 1000, clientHeight: 800, pageX: 0, pageY: 0 } };
+      }
+      if (method === "DOMSnapshot.captureSnapshot") {
+        return {
+          strings,
+          documents: [
+            {
+              nodes: {
+                parentIndex: [-1, 0],
+                nodeName: [i("body"), i("canvas")],
+                backendNodeId: [100, 200],
+                attributes: [[], []],
+              },
+              layout: {
+                nodeIndex: [0, 1],
+                styles: [
+                  [i("static"), i("auto"), i("auto")],
+                  [i("static"), i("auto"), i("auto")],
+                ],
+                bounds: [
+                  [0, 0, 1000, 800],
+                  [20, 30, 800, 500],
+                ],
+                paintOrders: [0, 1],
+              },
+            },
+          ],
+        };
+      }
+      throw new Error(`unexpected CDP method ${method}`);
+    });
+    const deps = {
+      cdp: {
+        send: send as unknown as <T = unknown>(
+          tabId: number,
+          method: string,
+          params?: object,
+        ) => Promise<T>,
+        trackSessionTab: vi.fn(),
+      },
+      tabsApi: {
+        get: vi.fn(
+          async (tabId: number) => ({ id: tabId, windowId: 100, active: true }) as chrome.tabs.Tab,
+        ),
+        query: vi.fn(async () => [{ id: 4, windowId: 100, active: true } as chrome.tabs.Tab]),
+      },
+      conditionalSurfaceProbe: false,
+    };
+
+    const observed = await handleObserve(sm, { session_id: "aa11" }, deps);
+    if ("code" in observed) throw new Error(`unexpected error: ${JSON.stringify(observed)}`);
+    expect(observed.text).toContain('@e1 surface "canvas visual surface"');
+    expect(ctx.refStore.resolveEntry("e1")).toMatchObject({
+      backendNodeId: 200,
+      kind: "surface",
+      capabilities: ["screenshot"],
+    });
+
+    const snapshot = await handleSnapshot(sm, { session_id: "aa11" }, deps);
+    if ("code" in snapshot) throw new Error(`unexpected error: ${JSON.stringify(snapshot)}`);
+    expect(snapshot.text).not.toContain("visual surface");
+    expect(snapshot.ref_count).toBe(0);
+  });
+
   it("allows passive snapshots of explicit user-window tabs", async () => {
     const sm = new SessionManager({ agentWindow: fakeAgentWindow([100]) });
     await sm.start("aa11");
@@ -3155,6 +3304,98 @@ describe("handleSnapshot", () => {
     });
   });
 
+  it("decorates live observations with active controlled content", async () => {
+    const strings = [
+      "html",
+      "body",
+      "button",
+      "div",
+      "#text",
+      "role",
+      "tab",
+      "aria-selected",
+      "true",
+      "aria-controls",
+      "reviews-panel",
+      "id",
+      "static",
+      "auto",
+      "visible",
+      "1",
+      "A detailed review",
+    ];
+    const index = (value: string) => strings.indexOf(value);
+    const style = [index("static"), index("auto"), index("auto"), index("visible"), index("1")];
+    const snapshot = {
+      strings,
+      documents: [
+        {
+          nodes: {
+            parentIndex: [-1, 0, 1, 1, 3],
+            nodeName: [index("html"), index("body"), index("button"), index("div"), index("#text")],
+            backendNodeId: [10, 11, 12, 13, 14],
+            attributes: [
+              [],
+              [],
+              [
+                index("role"),
+                index("tab"),
+                index("aria-selected"),
+                index("true"),
+                index("aria-controls"),
+                index("reviews-panel"),
+              ],
+              [index("id"), index("reviews-panel")],
+              [],
+            ],
+            nodeValue: [-1, -1, -1, -1, index("A detailed review")],
+          },
+          layout: {
+            nodeIndex: [0, 1, 2, 3, 4],
+            styles: [style, style, style, style, style],
+            bounds: [
+              [0, 0, 1000, 800],
+              [0, 0, 1000, 800],
+              [20, 20, 120, 40],
+              [20, 80, 500, 200],
+              [20, 80, 200, 20],
+            ],
+            paintOrders: [0, 0, 1, 1, 1],
+          },
+        },
+      ],
+    };
+    const ax: CdpAxNode[] = [
+      {
+        nodeId: "root",
+        backendDOMNodeId: 11,
+        role: { type: "role", value: "RootWebArea" },
+        childIds: ["reviews"],
+      },
+      {
+        nodeId: "reviews",
+        parentId: "root",
+        backendDOMNodeId: 12,
+        role: { type: "role", value: "tab" },
+        name: { type: "computedString", value: "Reviews" },
+        properties: [
+          { name: "selected", value: { value: true } },
+          { name: "controls", value: { value: "reviews-panel" } },
+        ],
+      },
+    ];
+
+    const result = await captureVomObservation(
+      makeOverlayDeps(ax, snapshot, VP_METRICS).cdp,
+      4,
+      "https://example.com",
+    );
+
+    expect(result.text).toContain('@e1 tab "Reviews"');
+    expect(result.text).toContain("[§ active: Reviews]");
+    expect(result.text).toContain("A detailed review");
+  });
+
   it("does not leak form secrets through the record-safe observation payload", async () => {
     const secrets = {
       email: "user@example.com",

apps/extension/src/tools/__tests__/record-steps.test.ts

@@ -15,7 +15,12 @@ import {
 const AGENT_WINDOW_ID = 100;
 const TAB_ID = 4;
 const START_URL = "https://example.com/";
-const RECORD_START_V3 = { session_id: "abcd", url: START_URL, trace_version: 3 as const };
+const RECORD_START_V3 = {
+  session_id: "abcd",
+  url: START_URL,
+  trace_version: 3 as const,
+  supports_tab_switch_steps: true,
+};
 const stepSequenceByProducer = new Map<string, number>();
 
 function asTraceV3(trace: RecordedTrace): TraceV3 {
@@ -48,6 +53,7 @@ function chromeEvent<T extends (...args: never[]) => unknown>() {
 
 function installChrome() {
   const runtimeOnMessage = chromeEvent<RuntimeListener>();
+  const tabsOnActivated = chromeEvent<(activeInfo: chrome.tabs.TabActiveInfo) => unknown>();
   const webNavigationOnCompleted =
     chromeEvent<(details: chrome.webNavigation.WebNavigationFramedCallbackDetails) => unknown>();
   const webNavigationOnCommitted =
@@ -57,7 +63,7 @@ function installChrome() {
   vi.stubGlobal("chrome", {
     runtime: { onMessage: runtimeOnMessage },
     tabs: {
-      onActivated: chromeEvent(),
+      onActivated: tabsOnActivated,
       onCreated: chromeEvent(),
       onUpdated: chromeEvent(),
     },
@@ -66,7 +72,7 @@ function installChrome() {
       onCommitted: webNavigationOnCommitted,
     },
   });
-  return { runtimeOnMessage, webNavigationOnCompleted, webNavigationOnCommitted };
+  return { runtimeOnMessage, tabsOnActivated, webNavigationOnCompleted, webNavigationOnCommitted };
 }
 
 function fakeManager() {
@@ -118,7 +124,10 @@ type FakeCdp = CdpRunner & {
 const LONG_IDLE_MS = 10_000;
 
 /** AX-only page: DOMSnapshot calls throw so capture falls back to the AX tree. */
-function makeFakeCdp(trees?: unknown[], options?: { failCaptures?: boolean }): FakeCdp {
+function makeFakeCdp(
+  trees?: unknown[],
+  options?: { failCaptures?: boolean; treesByTab?: Record<number, unknown> },
+): FakeCdp {
   type EventListener = (source: chrome.debugger.Debuggee, method: string, params: unknown) => void;
   const events: EventListener[] = [];
   const script = [...(trees ?? [])];
@@ -153,6 +162,8 @@ function makeFakeCdp(trees?: unknown[], options?: { failCaptures?: boolean }): F
     "Accessibility.enable": () => ({}),
     "Accessibility.getFullAXTree": (_params, _tabId) => {
       if (failing) throw new Error("Execution context was destroyed");
+      const tabTree = options?.treesByTab?.[_tabId];
+      if (tabTree) return tabTree;
       if (script.length === 0) return axTree("Example Domain", ["Submit"]);
       return script.length === 1 ? script[0] : script.shift();
     },
@@ -202,6 +213,31 @@ function makeTabsApi() {
   };
 }
 
+function makeMultiTabsApi(tabs: chrome.tabs.Tab[]) {
+  const byId = new Map(tabs.flatMap((tab) => (typeof tab.id === "number" ? [[tab.id, tab]] : [])));
+  return {
+    get: async (tabId: number) => {
+      const tab = byId.get(tabId);
+      if (!tab) throw new Error(`tab ${tabId} closed`);
+      return tab;
+    },
+    query: async (query: chrome.tabs.QueryInfo) =>
+      [...byId.values()].filter(
+        (tab) =>
+          (query.windowId === undefined || tab.windowId === query.windowId) &&
+          (query.active === undefined || tab.active === query.active),
+      ),
+    activate(tabId: number) {
+      for (const tab of byId.values()) tab.active = tab.id === tabId;
+    },
+    goTo(tabId: number, url: string, title: string) {
+      const tab = byId.get(tabId);
+      if (!tab) throw new Error(`tab ${tabId} closed`);
+      Object.assign(tab, { url, title });
+    },
+  };
+}
+
 /** Outlast a settle on a quiet page plus the per-tab observation cooldown. */
 function settleWait(): Promise<void> {
   return new Promise((resolve) => setTimeout(resolve, 800));
@@ -212,16 +248,19 @@ function runtimeOnMessageEmit(
   requestId: string,
   step: unknown,
   tabId = TAB_ID,
-): void {
+  active = true,
+): ReturnType<typeof vi.fn> {
   const producerId = `test-producer-${tabId}`;
   const producerKey = `${requestId}:${producerId}`;
   const sequence = (stepSequenceByProducer.get(producerKey) ?? 0) + 1;
   stepSequenceByProducer.set(producerKey, sequence);
+  const sendResponse = vi.fn();
   chromeApi.runtimeOnMessage.emit(
     { type: RECORD_STEP, requestId, producerId, sequence, step },
-    { tab: { id: tabId } } as chrome.runtime.MessageSender,
-    () => {},
+    { tab: { id: tabId, active } } as chrome.runtime.MessageSender,
+    sendResponse,
   );
+  return sendResponse;
 }
 
 describe("recorded user steps reach the exported trace", () => {
@@ -1161,7 +1200,8 @@ describe("recorded user steps reach the exported trace", () => {
     const trace = (stopped as RecordStopResult).trace;
     expect("version" in trace).toBe(false);
     expect("pages" in trace && trace.pages.length).toBeGreaterThan(0);
-    expect("steps" in trace && trace.steps.map((step) => step.op)).toEqual(["hover", "click"]);
+    // `hover` has no v2 counterpart on peers that negotiate v2.
+    expect("steps" in trace && trace.steps.map((step) => step.op)).toEqual(["click"]);
   });
 
   it("rejects unsupported trace_version values", async () => {
@@ -1173,4 +1213,391 @@ describe("recorded user steps reach the exported trace", () => {
     );
     expect(result).toMatchObject({ code: "invalid_params" });
   });
+
+  it("records tab transitions and binds actions to each tab's observation", async () => {
+    const chromeApi = installChrome();
+    const manager = fakeManager();
+    const secondUrl = "https://example.com/second";
+    const tabsApi = makeMultiTabsApi([
+      {
+        id: TAB_ID,
+        windowId: AGENT_WINDOW_ID,
+        active: true,
+        status: "complete",
+        url: START_URL,
+        title: "First tab",
+      } as chrome.tabs.Tab,
+      {
+        id: 5,
+        windowId: AGENT_WINDOW_ID,
+        active: false,
+        status: "complete",
+        url: secondUrl,
+        title: "Second tab",
+      } as chrome.tabs.Tab,
+    ]);
+    const cdp = makeFakeCdp(undefined, {
+      treesByTab: {
+        [TAB_ID]: axTree("First tab", ["First action"]),
+        5: axTree("Second tab", ["Second action"]),
+      },
+    });
+    let requestId = "";
+    const sendToTab = vi.fn(async (_tabId: number, message: unknown) => {
+      const typed = message as { type?: string; requestId?: string };
+      if (typed.type === RECORD_START && typed.requestId) requestId = typed.requestId;
+      return { ok: true };
+    });
+    const deps = { tabsApi, sendToTab, cdp };
+
+    await handleRecordStart(manager, RECORD_START_V3, deps);
+    attachRecordStepListener(deps);
+    tabsApi.activate(5);
+    chromeApi.tabsOnActivated.emit({ tabId: 5, windowId: AGENT_WINDOW_ID });
+    await settleWait();
+    runtimeOnMessageEmit(
+      chromeApi,
+      requestId,
+      {
+        op: "click",
+        page_url: secondUrl,
+        target: { role: "button", name: "Second action", tag: "button" },
+      },
+      5,
+    );
+    await settleWait();
+
+    tabsApi.activate(TAB_ID);
+    chromeApi.tabsOnActivated.emit({ tabId: TAB_ID, windowId: AGENT_WINDOW_ID });
+    await settleWait();
+    runtimeOnMessageEmit(chromeApi, requestId, {
+      op: "click",
+      page_url: START_URL,
+      target: { role: "button", name: "First action", tag: "button" },
+    });
+    await settleWait();
+
+    const stopped = await handleRecordStop(manager, { session_id: "abcd" }, deps);
+    const trace = asTraceV3((stopped as RecordStopResult).trace);
+    const stateUrl = (stateId: string) => trace.states.find((state) => state.id === stateId)?.url;
+    const switches = trace.steps.filter((step) => step.op === "switch_tab");
+    const clicks = trace.steps.filter((step) => step.op === "click");
+
+    expect(switches).toHaveLength(2);
+    expect(clicks).toHaveLength(2);
+    expect(stateUrl(switches[0]!.state)).toBe(START_URL);
+    expect(stateUrl(switches[0]!.result.state)).toBe(secondUrl);
+    expect(stateUrl(clicks[0]!.state)).toBe(secondUrl);
+    expect(stateUrl(switches[1]!.result.state)).toBe(START_URL);
+    expect(stateUrl(clicks[1]!.state)).toBe(START_URL);
+  });
+
+  it("keeps switch_tab internal when the v3 caller did not advertise support", async () => {
+    const chromeApi = installChrome();
+    const manager = fakeManager();
+    const tabsApi = makeMultiTabsApi([
+      {
+        id: TAB_ID,
+        windowId: AGENT_WINDOW_ID,
+        active: true,
+        status: "complete",
+        url: START_URL,
+      } as chrome.tabs.Tab,
+      {
+        id: 5,
+        windowId: AGENT_WINDOW_ID,
+        active: false,
+        status: "complete",
+        url: "https://example.com/second",
+      } as chrome.tabs.Tab,
+    ]);
+    const deps = { tabsApi, sendToTab: vi.fn(async () => ({ ok: true })), cdp: makeFakeCdp() };
+
+    await handleRecordStart(
+      manager,
+      { session_id: "abcd", url: START_URL, trace_version: 3 },
+      deps,
+    );
+    tabsApi.activate(5);
+    chromeApi.tabsOnActivated.emit({ tabId: 5, windowId: AGENT_WINDOW_ID });
+    await settleWait();
+
+    const stopped = await handleRecordStop(manager, { session_id: "abcd" }, deps);
+    const trace = asTraceV3((stopped as RecordStopResult).trace);
+    expect(trace.steps.some((step) => step.op === "switch_tab")).toBe(false);
+  });
+
+  it("keeps the latest rapid tab activation when an earlier rearm acknowledges late", async () => {
+    const chromeApi = installChrome();
+    const manager = fakeManager();
+    const tabsApi = makeMultiTabsApi(
+      [TAB_ID, 5, 6].map(
+        (id) =>
+          ({
+            id,
+            windowId: AGENT_WINDOW_ID,
+            active: id === TAB_ID,
+            status: "complete",
+            url: id === TAB_ID ? START_URL : `https://example.com/tab-${id}`,
+          }) as chrome.tabs.Tab,
+      ),
+    );
+    let releaseSecond!: () => void;
+    const secondGate = new Promise<void>((resolve) => {
+      releaseSecond = resolve;
+    });
+    let announceSecond!: () => void;
+    const secondStarted = new Promise<void>((resolve) => {
+      announceSecond = resolve;
+    });
+    const sendToTab = vi.fn(async (tabId: number, message: unknown) => {
+      if ((message as { type?: string }).type === RECORD_START && tabId === 5) {
+        announceSecond();
+        await secondGate;
+      }
+      return { ok: true };
+    });
+    const deps = { tabsApi, sendToTab, cdp: makeFakeCdp() };
+
+    await handleRecordStart(manager, RECORD_START_V3, deps);
+    tabsApi.activate(5);
+    chromeApi.tabsOnActivated.emit({ tabId: 5, windowId: AGENT_WINDOW_ID });
+    await secondStarted;
+    tabsApi.activate(6);
+    chromeApi.tabsOnActivated.emit({ tabId: 6, windowId: AGENT_WINDOW_ID });
+    await settleWait();
+    releaseSecond();
+    await new Promise((resolve) => setTimeout(resolve, 50));
+
+    const stopped = await handleRecordStop(manager, { session_id: "abcd" }, deps);
+    const trace = asTraceV3((stopped as RecordStopResult).trace);
+    const switches = trace.steps.filter((step) => step.op === "switch_tab");
+    const stateUrl = (stateId: string) => trace.states.find((state) => state.id === stateId)?.url;
+    expect(switches).toHaveLength(1);
+    expect(stateUrl(switches[0]!.result.state)).toBe("https://example.com/tab-6");
+  });
+
+  it("does not retry an in-flight tab rearm after recording stops", async () => {
+    const chromeApi = installChrome();
+    const manager = fakeManager();
+    const tabsApi = makeMultiTabsApi([
+      {
+        id: TAB_ID,
+        windowId: AGENT_WINDOW_ID,
+        active: true,
+        status: "complete",
+        url: START_URL,
+      } as chrome.tabs.Tab,
+      {
+        id: 5,
+        windowId: AGENT_WINDOW_ID,
+        active: false,
+        status: "complete",
+        url: "https://example.com/second",
+      } as chrome.tabs.Tab,
+    ]);
+    let failRearm!: () => void;
+    const rearmGate = new Promise<never>((_resolve, reject) => {
+      failRearm = () => reject(new Error("rearm failed after stop"));
+    });
+    let announceRearm!: () => void;
+    const rearmStarted = new Promise<void>((resolve) => {
+      announceRearm = resolve;
+    });
+    const sendToTab = vi.fn(async (tabId: number, message: unknown) => {
+      if ((message as { type?: string }).type === RECORD_START && tabId === 5) {
+        announceRearm();
+        await rearmGate;
+      }
+      return { ok: true };
+    });
+    const deps = { tabsApi, sendToTab, cdp: makeFakeCdp() };
+
+    await handleRecordStart(manager, RECORD_START_V3, deps);
+    tabsApi.activate(5);
+    chromeApi.tabsOnActivated.emit({ tabId: 5, windowId: AGENT_WINDOW_ID });
+    await rearmStarted;
+
+    const stoppedPromise = handleRecordStop(manager, { session_id: "abcd" }, deps);
+    await vi.waitFor(() => {
+      expect(sendToTab).toHaveBeenCalledWith(5, expect.objectContaining({ type: RECORD_STOP }));
+    });
+    failRearm();
+    const stopped = await stoppedPromise;
+    await new Promise((resolve) => setTimeout(resolve, 600));
+
+    const startsForSecondTab = sendToTab.mock.calls.filter(
+      ([tabId, message]) => tabId === 5 && (message as { type?: string }).type === RECORD_START,
+    );
+    expect(startsForSecondTab).toHaveLength(1);
+    expect(asTraceV3((stopped as RecordStopResult).trace).steps).toHaveLength(0);
+  });
+
+  it("keeps pending action settles scoped to their tab during an immediate switch", async () => {
+    const chromeApi = installChrome();
+    const manager = fakeManager();
+    const secondUrl = "https://example.com/second";
+    const tabsApi = makeMultiTabsApi([
+      {
+        id: TAB_ID,
+        windowId: AGENT_WINDOW_ID,
+        active: true,
+        status: "complete",
+        url: START_URL,
+      } as chrome.tabs.Tab,
+      {
+        id: 5,
+        windowId: AGENT_WINDOW_ID,
+        active: false,
+        status: "complete",
+        url: secondUrl,
+      } as chrome.tabs.Tab,
+    ]);
+    let requestId = "";
+    const sendToTab = vi.fn(async (_tabId: number, message: unknown) => {
+      const typed = message as { type?: string; requestId?: string };
+      if (typed.type === RECORD_START && typed.requestId) requestId = typed.requestId;
+      return { ok: true };
+    });
+    const deps = { tabsApi, sendToTab, cdp: makeFakeCdp() };
+
+    await handleRecordStart(manager, RECORD_START_V3, deps);
+    attachRecordStepListener(deps);
+    runtimeOnMessageEmit(chromeApi, requestId, {
+      op: "click",
+      page_url: START_URL,
+      target: { role: "button", name: "First action", tag: "button" },
+    });
+    tabsApi.activate(5);
+    chromeApi.tabsOnActivated.emit({ tabId: 5, windowId: AGENT_WINDOW_ID });
+    runtimeOnMessageEmit(
+      chromeApi,
+      requestId,
+      {
+        op: "click",
+        page_url: secondUrl,
+        target: { role: "button", name: "Second action", tag: "button" },
+      },
+      5,
+    );
+    await settleWait();
+
+    const stopped = await handleRecordStop(manager, { session_id: "abcd" }, deps);
+    const trace = asTraceV3((stopped as RecordStopResult).trace);
+    const stateUrl = (stateId: string) => trace.states.find((state) => state.id === stateId)?.url;
+
+    expect(trace.steps.map((step) => step.op)).toEqual(["click", "switch_tab", "click"]);
+    expect(stateUrl(trace.steps[0]!.result.state)).toBe(START_URL);
+    expect(stateUrl(trace.steps[1]!.result.state)).toBe(secondUrl);
+    expect(stateUrl(trace.steps[2]!.state)).toBe(secondUrl);
+  });
+
+  it("tracks the same navigation URL independently for each tab", async () => {
+    const chromeApi = installChrome();
+    const manager = fakeManager();
+    const tabsApi = makeMultiTabsApi([
+      {
+        id: TAB_ID,
+        windowId: AGENT_WINDOW_ID,
+        active: true,
+        status: "complete",
+        url: START_URL,
+      } as chrome.tabs.Tab,
+      {
+        id: 5,
+        windowId: AGENT_WINDOW_ID,
+        active: false,
+        status: "complete",
+        url: "https://example.com/second",
+      } as chrome.tabs.Tab,
+    ]);
+    const deps = { tabsApi, sendToTab: vi.fn(async () => ({ ok: true })), cdp: makeFakeCdp() };
+
+    await handleRecordStart(manager, RECORD_START_V3, deps);
+    tabsApi.activate(5);
+    chromeApi.tabsOnActivated.emit({ tabId: 5, windowId: AGENT_WINDOW_ID });
+    await settleWait();
+    tabsApi.goTo(5, START_URL, "Same URL in second tab");
+    chromeApi.webNavigationOnCommitted.emit({
+      tabId: 5,
+      frameId: 0,
+      url: START_URL,
+      transitionType: "typed",
+      transitionQualifiers: ["from_address_bar"],
+    } as unknown as chrome.webNavigation.WebNavigationTransitionCallbackDetails);
+    await settleWait();
+
+    const stopped = await handleRecordStop(manager, { session_id: "abcd" }, deps);
+    const trace = asTraceV3((stopped as RecordStopResult).trace);
+    expect(
+      trace.steps.filter((step) => step.op === "navigate" && step.to === START_URL),
+    ).toHaveLength(1);
+  });
+
+  it("drops late input and frame navigation from an inactive tab", async () => {
+    const chromeApi = installChrome();
+    const manager = fakeManager();
+    const secondUrl = "https://example.com/second";
+    const tabsApi = makeMultiTabsApi([
+      {
+        id: TAB_ID,
+        windowId: AGENT_WINDOW_ID,
+        active: true,
+        status: "complete",
+        url: START_URL,
+      } as chrome.tabs.Tab,
+      {
+        id: 5,
+        windowId: AGENT_WINDOW_ID,
+        active: false,
+        status: "complete",
+        url: secondUrl,
+      } as chrome.tabs.Tab,
+    ]);
+    let requestId = "";
+    const sendToTab = vi.fn(async (_tabId: number, message: unknown) => {
+      const typed = message as { type?: string; requestId?: string };
+      if (typed.type === RECORD_START && typed.requestId) requestId = typed.requestId;
+      return { ok: true };
+    });
+    const deps = { tabsApi, sendToTab, cdp: makeFakeCdp() };
+
+    await handleRecordStart(manager, RECORD_START_V3, deps);
+    attachRecordStepListener(deps);
+    tabsApi.activate(5);
+    chromeApi.tabsOnActivated.emit({ tabId: 5, windowId: AGENT_WINDOW_ID });
+    await settleWait();
+    const lateAck = runtimeOnMessageEmit(
+      chromeApi,
+      requestId,
+      {
+        op: "fill",
+        page_url: START_URL,
+        target: { role: "textbox", name: "Draft", tag: "input" },
+        value: "late",
+      },
+      TAB_ID,
+      false,
+    );
+    expect(lateAck).toHaveBeenCalledWith({ ok: true, sequence: 1 });
+    chromeApi.webNavigationOnCommitted.emit({
+      tabId: TAB_ID,
+      frameId: 0,
+      url: "https://example.com/late",
+      transitionType: "link",
+      transitionQualifiers: [],
+    } as unknown as chrome.webNavigation.WebNavigationTransitionCallbackDetails);
+    chromeApi.webNavigationOnCommitted.emit({
+      tabId: 5,
+      frameId: 7,
+      url: "https://frame.example/late",
+      transitionType: "link",
+      transitionQualifiers: [],
+    } as unknown as chrome.webNavigation.WebNavigationTransitionCallbackDetails);
+    await new Promise((resolve) => setTimeout(resolve, 50));
+
+    const stopped = await handleRecordStop(manager, { session_id: "abcd" }, deps);
+    const trace = asTraceV3((stopped as RecordStopResult).trace);
+    expect(trace.steps.map((step) => step.op)).toEqual(["switch_tab"]);
+  });
 });

apps/extension/src/tools/__tests__/snapshot-ref.test.ts

@@ -24,10 +24,14 @@ describe("lookupSnapshotRef", () => {
     expect(lookupSnapshotRef(ctx, "@e3", 4)).toEqual({
       backendNodeId: 1234,
       refKey: "e3",
+      kind: "dom",
+      capabilities: ["interact", "screenshot"],
     });
     expect(lookupSnapshotRef(ctx, "e3", 4)).toEqual({
       backendNodeId: 1234,
       refKey: "e3",
+      kind: "dom",
+      capabilities: ["interact", "screenshot"],
     });
   });
 
@@ -53,6 +57,8 @@ describe("resolveSnapshotRef", () => {
       tabId: 4,
       frameId: "child-frame",
       cdpSessionId: "child-session",
+      kind: "dom",
+      capabilities: ["interact", "screenshot"],
     });
 
     const expected = {
@@ -60,6 +66,8 @@ describe("resolveSnapshotRef", () => {
       refKey: "e3",
       frameId: "child-frame",
       cdpSessionId: "child-session",
+      kind: "dom" as const,
+      capabilities: ["interact", "screenshot"] as const,
     };
     expect(lookupSnapshotRef(ctx, "@e3", 4)).toEqual(expected);
     expect(resolveSnapshotRef(ctx, "@e3", 4)).toEqual(expected);
@@ -105,6 +113,28 @@ describe("resolveSnapshotRef", () => {
     expect(resolveSnapshotRef(ctx, "@e3", 4)).toEqual({
       backendNodeId: 1234,
       refKey: "e3",
+      kind: "dom",
+      capabilities: ["interact", "screenshot"],
+    });
+  });
+
+  it("rejects an operation outside the ref's declared capabilities", async () => {
+    const sm = new SessionManager({ agentWindow: fakeAgentWindow([100]) });
+    const ctx = await sm.start("aa11");
+    ctx.refStore.set("e3", 1234, {
+      tabId: 4,
+      kind: "surface",
+      capabilities: ["screenshot"],
+    });
+
+    expect(resolveSnapshotRef(ctx, "@e3", 4, "interact")).toMatchObject({
+      code: "permission_denied",
+      message: "ref @e3 does not support interact",
+      data: {
+        reason: "ref_capability_denied",
+        required_capability: "interact",
+        kind: "surface",
+      },
     });
   });
 });

apps/extension/src/tools/dispatcher.ts

@@ -51,7 +51,12 @@ import {
   handleScreenshot,
   handleSnapshot,
 } from "./observation";
-import { handleRecordAwait, handleRecordStart, handleRecordStop } from "./record";
+import {
+  handleRecordAwait,
+  handleRecordStart,
+  handleRecordStop,
+  type RecordRuntimeDeps,
+} from "./record";
 import {
   handleSessionStart,
   handleSessionStop,
@@ -99,6 +104,7 @@ export interface DispatcherDeps {
   transport: Transport;
   sessions: SessionManager;
   cdp?: DispatcherCdpRunner;
+  recording?: RecordRuntimeDeps;
   /**
    * Invoked whenever a dispatched RPC may have changed the live
    * session set (currently `tool.session_start` and
@@ -134,6 +140,7 @@ export class ToolDispatcher {
   private readonly transport: Transport;
   private readonly sessions: SessionManager;
   private readonly cdp?: DispatcherCdpRunner;
+  private readonly recording?: RecordRuntimeDeps;
   private readonly onSessionsChanged?: () => void;
   private readonly onBrowserControlResumed?: (sessionId: string) => void;
   private readonly approveBorrow?: BorrowConfirmationApprover;
@@ -153,6 +160,7 @@ export class ToolDispatcher {
     this.transport = deps.transport;
     this.sessions = deps.sessions;
     this.cdp = deps.cdp;
+    this.recording = deps.recording;
     this.onSessionsChanged = deps.onSessionsChanged;
     this.onBrowserControlResumed = deps.onBrowserControlResumed;
     this.approveBorrow = deps.approveBorrow;
@@ -531,44 +539,26 @@ export class ToolDispatcher {
           signal,
         });
       case "tool.record_start":
-        return handleRecordStart(this.sessions, req.params as RecordStartParams, {
-          tabsApi: chromeTabsApi,
-          sendToTab: (tabId, msg) => chrome.tabs.sendMessage(tabId, msg),
-          bypassOverlay: async (tabId, enabled) => {
-            try {
-              await chrome.tabs.sendMessage(tabId, {
-                type: OVERLAY_AUTOMATION_BYPASS,
-                enabled,
-              });
-            } catch {
-              // Content script may be unavailable on restricted pages.
-            }
-          },
-          ...(this.cdp ? { cdp: this.cdp } : {}),
-          signal,
-        });
+        return this.recording
+          ? handleRecordStart(this.sessions, req.params as RecordStartParams, {
+              ...this.recording,
+              signal,
+            })
+          : recordingRuntimeUnavailable();
       case "tool.record_stop":
-        return handleRecordStop(this.sessions, req.params as RecordStopParams, {
-          tabsApi: chromeTabsApi,
-          sendToTab: (tabId, msg) => chrome.tabs.sendMessage(tabId, msg),
-          bypassOverlay: async (tabId, enabled) => {
-            try {
-              await chrome.tabs.sendMessage(tabId, {
-                type: OVERLAY_AUTOMATION_BYPASS,
-                enabled,
-              });
-            } catch {
-              // Content script may be unavailable on restricted pages.
-            }
-          },
-          signal,
-        });
+        return this.recording
+          ? handleRecordStop(this.sessions, req.params as RecordStopParams, {
+              ...this.recording,
+              signal,
+            })
+          : recordingRuntimeUnavailable();
       case "tool.record_await":
-        return handleRecordAwait(this.sessions, req.params as RecordAwaitParams, {
-          tabsApi: chromeTabsApi,
-          sendToTab: (tabId, msg) => chrome.tabs.sendMessage(tabId, msg),
-          signal,
-        });
+        return this.recording
+          ? handleRecordAwait(this.sessions, req.params as RecordAwaitParams, {
+              ...this.recording,
+              signal,
+            })
+          : recordingRuntimeUnavailable();
       default:
         return {
           code: "unknown_method",
@@ -704,6 +694,13 @@ function isRpcError(v: unknown): v is RpcError {
   );
 }
 
+function recordingRuntimeUnavailable(): RpcError {
+  return {
+    code: "protocol_error",
+    message: "recording runtime is unavailable",
+  };
+}
+
 function sessionIdForBrowserControlMethod(req: RequestFrame): string | null {
   switch (req.method) {
     case "tool.tab_create":

apps/extension/src/tools/interaction.ts

@@ -159,7 +159,7 @@ async function resolveBackendNode(
     };
   }
   if (hasRef) {
-    const resolved = resolveSnapshotRef(ctx, params.ref as string, target.tabId);
+    const resolved = resolveSnapshotRef(ctx, params.ref as string, target.tabId, "interact");
     if (isRpcError(resolved)) return resolved;
     return {
       backendNodeId: resolved.backendNodeId,

apps/extension/src/tools/record.ts

@@ -18,8 +18,18 @@ import {
   type RecordStepAck,
   type RecordStopMessage,
 } from "@/lib/record-bridge";
+import {
+  type RecordFrameCoordinator,
+  type RecordingCaptureScope,
+  recordFrameCoordinator,
+} from "@/lib/recording/frame-coordinator";
 import { RecordingObservationRuntime } from "@/lib/recording/recording-runtime";
-import { appendRecordedPayload, observeRecordedNavigation } from "@/lib/recording/step-buffer";
+import {
+  appendRecordedPayload,
+  observeRecordedNavigation,
+  type RecordingStepBuffer,
+} from "@/lib/recording/step-buffer";
+import { RecordingTabCoordinator, type TabActivation } from "@/lib/recording/tab-coordinator";
 import { buildTraceV2 } from "@/lib/recording/trace-reducer-v2";
 import type { RecordingDraftStep } from "@/lib/recording/types";
 import type { SessionManager } from "@/session-manager/manager";
@@ -48,7 +58,7 @@ import {
 
 interface ActiveRecording {
   requestId: string;
-  tabId: number;
+  tabs: RecordingTabCoordinator;
   agentWindowId: number;
   startUrl?: string;
   purpose?: string;
@@ -56,14 +66,12 @@ interface ActiveRecording {
   startedAt: string;
   startedAtMs: number;
   traceVersion: 2 | 3;
+  supportsTabSwitchSteps: boolean;
   finishPromise: Promise<RecordedTrace>;
   resolveFinish: (trace: RecordedTrace) => void;
   rejectFinish: (err: Error) => void;
   settled: boolean;
   finishAttempt: Promise<RecordedTrace | null> | null;
-  currentUrl?: string;
-  pendingNavigation: boolean;
-  pendingNavigationDeadline?: number;
   observation: RecordingObservationRuntime | null;
   stoppedBy: StopReason;
   /** Navigation callbacks tracked from event receipt through action enqueue. */
@@ -79,8 +87,17 @@ interface ActiveRecording {
   lastStepSequenceByProducer: Map<string, number>;
 }
 
-function enqueueRecordingAction(recording: ActiveRecording, task: () => Promise<void>): void {
-  recording.actionQueue = recording.actionQueue.then(task, task).catch(() => {});
+function enqueueRecordingAction(
+  recording: ActiveRecording,
+  task: () => Promise<void>,
+): Promise<void> {
+  const queued = recording.actionQueue.then(task, task);
+  recording.actionQueue = queued.catch(() => {});
+  return queued;
+}
+
+function isRecordingFinishing(recording: ActiveRecording): boolean {
+  return recording.settled || recording.finishAttempt !== null;
 }
 
 const recordings = new Map<string, ActiveRecording>();
@@ -163,9 +180,11 @@ async function sendRecordStartWithAck(
   tabId: number,
   msg: RecordStartMessage,
   sendToTab: RecordDeps["sendToTab"],
+  cancelled?: () => boolean,
 ): Promise<void> {
   let lastError: unknown;
   for (let attempt = 0; attempt < RECORD_START_RETRIES; attempt += 1) {
+    if (cancelled?.()) throw new Error("record start cancelled");
     try {
       const response = await sendToTab(tabId, msg);
       if (isRecordStartAck(response)) return;
@@ -173,6 +192,7 @@ async function sendRecordStartWithAck(
     } catch (err) {
       lastError = err;
     }
+    if (cancelled?.()) throw new Error("record start cancelled");
     if (attempt + 1 < RECORD_START_RETRIES) {
       await sleep(RECORD_START_RETRY_DELAY_MS);
     }
@@ -198,6 +218,7 @@ function buildTrace(recording: ActiveRecording): RecordedTrace {
       startUrl: recording.startUrl,
       stoppedBy: recording.stoppedBy,
       bskVersion: BSK_TRACE_VERSION,
+      includeTabSwitches: recording.supportsTabSwitchSteps,
     });
   }
   if (recording.traceVersion === 3) {
@@ -211,14 +232,46 @@ function buildTrace(recording: ActiveRecording): RecordedTrace {
   });
 }
 
+function stepBufferFor(
+  recording: ActiveRecording,
+  tabId: number,
+  fallbackUrl?: string,
+): RecordingStepBuffer {
+  return {
+    steps: recording.steps,
+    navigation: recording.tabs.navigation(tabId, fallbackUrl),
+  };
+}
+
+async function activateRecordingTab(
+  recording: ActiveRecording,
+  targetTabId: number,
+): Promise<void> {
+  const previousTabId = recording.tabs.currentTabId;
+  if (targetTabId === previousTabId) return;
+
+  const transition = recording.observation
+    ? await recording.observation.captureTabTransition(previousTabId, targetTabId)
+    : {};
+  const { targetUrl, ...stateLinks } = transition;
+  const draft: Extract<RecordingDraftStep, { op: "switch_tab" }> = {
+    op: "switch_tab",
+    ...stateLinks,
+  };
+  recording.steps.push(draft);
+  recording.observation?.bindTabTransition(draft, recording.steps.length);
+  recording.tabs.commit(targetTabId, targetUrl);
+}
+
 async function processRecordedStep(
   recording: ActiveRecording,
   draftIndex: number,
   tabId: number,
+  producerId?: string,
 ): Promise<void> {
   if (!recording.observation) return;
   try {
-    await recording.observation.processDraft(tabId, recording.steps, draftIndex);
+    await recording.observation.processDraft(tabId, recording.steps, draftIndex, producerId);
   } catch (err) {
     console.warn(`[bsk record] observation failed for step ${draftIndex + 1}`, err);
   }
@@ -231,16 +284,25 @@ export interface RecordDeps {
     msg: RecordStartMessage | RecordStopMessage | RecordCancelMessage,
   ): Promise<unknown>;
   bypassOverlay?: (tabId: number, enabled: boolean) => Promise<void>;
+  frameCoordinator?: Pick<
+    RecordFrameCoordinator,
+    "begin" | "armTab" | "sourceFor" | "stop" | "cancel"
+  >;
   cdp?: CdpRunner;
   signal?: AbortSignal;
 }
 
+export type RecordRuntimeDeps = Omit<RecordDeps, "frameCoordinator" | "signal"> & {
+  frameCoordinator: NonNullable<RecordDeps["frameCoordinator"]>;
+};
+
 let defaultDeps: RecordDeps | null = null;
 function getDefaultDeps(): RecordDeps {
   if (!defaultDeps) {
     defaultDeps = {
       tabsApi: chromeTabsApi,
       sendToTab: (tabId, msg) => chrome.tabs.sendMessage(tabId, msg),
+      frameCoordinator: recordFrameCoordinator,
     };
   }
   return defaultDeps;
@@ -307,8 +369,15 @@ export function attachRecordStepListener(deps: RecordDeps = getDefaultDeps()): (
     if (!isRecordStepMessage(message)) return false;
     for (const recording of recordings.values()) {
       if (recording.requestId !== message.requestId) continue;
-      const sourceTabId = sender.tab?.id ?? recording.tabId;
-      const producerKey = `${sourceTabId}:${message.producerId}`;
+      const source: RecordingCaptureScope | null | undefined = deps.frameCoordinator
+        ? deps.frameCoordinator.sourceFor(message.requestId, message.producerId, sender)
+        : undefined;
+      if (deps.frameCoordinator && !source) return false;
+      const sourceTabId = source?.tabId ?? sender.tab?.id ?? recording.tabs.currentTabId;
+      const sourceWasActive = sender.tab?.active ?? sourceTabId === recording.tabs.activeTabId;
+      const producerKey = source
+        ? `${source.tabId}:${source.documentId}:${source.producerId}`
+        : `${sourceTabId}:${message.producerId}`;
       const expectedSequence = (recording.lastStepSequenceByProducer.get(producerKey) ?? 0) + 1;
       if (message.sequence < expectedSequence) {
         sendResponse({ ok: true, sequence: message.sequence });
@@ -325,11 +394,21 @@ export function attachRecordStepListener(deps: RecordDeps = getDefaultDeps()): (
 
       recording.lastStepSequenceByProducer.set(producerKey, message.sequence);
       enqueueRecordingAction(recording, async () => {
-        await recording.observation?.flushRedirects();
+        if (sourceTabId !== recording.tabs.currentTabId) {
+          if (!sourceWasActive) return;
+          if (sourceTabId !== recording.tabs.activeTabId)
+            recording.tabs.noteActivation(sourceTabId);
+          await activateRecordingTab(recording, sourceTabId);
+        }
+        await recording.observation?.flushRedirects(sourceTabId);
         const targetHint = message.step.geometry ? { geometry: message.step.geometry } : undefined;
-        const draftIndex = appendRecordedPayload(recording, message.step, targetHint);
+        const draftIndex = appendRecordedPayload(
+          stepBufferFor(recording, sourceTabId, message.step.page_url),
+          message.step,
+          targetHint,
+        );
         if (draftIndex !== null) {
-          await processRecordedStep(recording, draftIndex, sourceTabId);
+          await processRecordedStep(recording, draftIndex, sourceTabId, source?.producerId);
         }
       });
       sendResponse({ ok: true, sequence: message.sequence });
@@ -359,7 +438,7 @@ export function attachRecordFinishListener(deps: RecordDeps = getDefaultDeps()):
 
 function findRecordingByTabId(tabId: number): ActiveRecording | null {
   for (const recording of recordings.values()) {
-    if (recording.tabId === tabId && !recording.settled) return recording;
+    if (recording.tabs.currentTabId === tabId && !recording.settled) return recording;
   }
   return null;
 }
@@ -396,7 +475,7 @@ async function clearRearmTimersForRecording(
   recording: ActiveRecording,
   deps: RecordDeps,
 ): Promise<void> {
-  clearRearmTimer(recording.tabId);
+  clearRearmTimer(recording.tabs.currentTabId);
   try {
     const tabs = await deps.tabsApi.query({ windowId: recording.agentWindowId });
     for (const tab of tabs) {
@@ -411,13 +490,16 @@ async function stopRecordingOnAllAgentTabs(
   recording: ActiveRecording,
   deps: RecordDeps,
 ): Promise<void> {
+  if (deps.frameCoordinator && !(await deps.frameCoordinator.stop(recording.requestId))) {
+    throw new Error("failed to flush one or more recording documents");
+  }
   const stopMsg: RecordStopMessage = { type: RECORD_STOP, requestId: recording.requestId };
-  let tabIds = [recording.tabId];
+  let tabIds = [recording.tabs.currentTabId];
   try {
     const tabs = await deps.tabsApi.query({ windowId: recording.agentWindowId });
     tabIds = [
       ...new Set([
-        recording.tabId,
+        recording.tabs.currentTabId,
         ...tabs.flatMap((tab) => (typeof tab.id === "number" ? [tab.id] : [])),
       ]),
     ];
@@ -428,11 +510,11 @@ async function stopRecordingOnAllAgentTabs(
   for (const tabId of tabIds) {
     try {
       const response = await deps.sendToTab(tabId, stopMsg);
-      if (tabId === recording.tabId && !isRecordStartAck(response)) {
+      if (tabId === recording.tabs.currentTabId && !isRecordStartAck(response)) {
         throw new Error("content script did not confirm recorded steps");
       }
     } catch {
-      if (tabId === recording.tabId) {
+      if (tabId === recording.tabs.currentTabId) {
         throw new Error("failed to flush recorded steps");
       }
     }
@@ -450,22 +532,39 @@ async function rearmRecording(
   recording: ActiveRecording,
   targetTabId: number,
   deps: RecordDeps,
+  activation?: TabActivation,
 ): Promise<boolean> {
   // Do NOT toggle automation-bypass here: each retry used to increment the
   // content-script counter, and a single stop decrement left the ControlOverlay
   // stuck with pointer-events:none (page usable, Interrupt dead). RecordOverlay
   // already hides the control chrome while activeRecord is set.
+  const isFinishing = () => isRecordingFinishing(recording);
   for (let attempt = 0; attempt < RECORD_REARM_MAX_ATTEMPTS; attempt += 1) {
+    if (isFinishing()) return false;
     const startMsg: RecordStartMessage = {
       type: RECORD_START,
       requestId: recording.requestId,
       startedAtMs: recording.startedAtMs,
     };
     try {
-      await sendRecordStartWithAck(targetTabId, startMsg, deps.sendToTab);
-      recording.tabId = targetTabId;
+      if (deps.frameCoordinator) {
+        const frameStarted = await deps.frameCoordinator.armTab(recording.requestId, targetTabId);
+        if (!frameStarted) throw new Error("recording document did not start");
+      }
+      await sendRecordStartWithAck(targetTabId, startMsg, deps.sendToTab, isFinishing);
+      if (isFinishing()) return false;
+      if (activation) {
+        if (!recording.tabs.isLatest(activation)) return true;
+        await enqueueRecordingAction(recording, async () => {
+          if (isFinishing() || !recording.tabs.isLatest(activation)) {
+            return;
+          }
+          await activateRecordingTab(recording, targetTabId);
+        });
+      }
       return true;
     } catch {
+      if (isFinishing()) return false;
       if (attempt + 1 < RECORD_REARM_MAX_ATTEMPTS) {
         await sleep(RECORD_REARM_RETRY_DELAY_MS);
       }
@@ -474,7 +573,7 @@ async function rearmRecording(
   return false;
 }
 
-function scheduleRearmForTab(tabId: number, deps: RecordDeps): void {
+function scheduleRearmForTab(tabId: number, deps: RecordDeps, activation?: TabActivation): void {
   const existing = rearmTimers.get(tabId);
   if (existing) clearTimeout(existing);
   rearmTimers.set(
@@ -483,7 +582,7 @@ function scheduleRearmForTab(tabId: number, deps: RecordDeps): void {
       rearmTimers.delete(tabId);
       void (async () => {
         const current = await findRecordingForTab(tabId, deps);
-        if (current) await rearmRecording(current, tabId, deps);
+        if (current) await rearmRecording(current, tabId, deps, activation);
       })();
     }, RECORD_REARM_DEBOUNCE_MS),
   );
@@ -495,14 +594,20 @@ export function attachRecordTabListener(deps: RecordDeps = getDefaultDeps()): ()
     const windowId = tab.windowId;
     if (tabId === undefined || windowId === undefined) return;
     for (const recording of recordings.values()) {
-      if (recording.settled || recording.agentWindowId !== windowId) continue;
+      if (isRecordingFinishing(recording) || recording.agentWindowId !== windowId) continue;
       scheduleRearmForTab(tabId, deps);
       return;
     }
   };
 
   const onActivated = (activeInfo: chrome.tabs.TabActiveInfo) => {
-    scheduleRearmForTab(activeInfo.tabId, deps);
+    for (const recording of recordings.values()) {
+      if (isRecordingFinishing(recording) || recording.agentWindowId !== activeInfo.windowId)
+        continue;
+      const activation = recording.tabs.noteActivation(activeInfo.tabId);
+      scheduleRearmForTab(activeInfo.tabId, deps, activation);
+      return;
+    }
   };
 
   chrome.tabs.onCreated.addListener(onCreated);
@@ -522,54 +627,39 @@ export function attachRecordNavigationListener(deps: RecordDeps = getDefaultDeps
     transitionQualifiers?: string[],
   ) => {
     if (!url) return;
-    const direct = findRecordingByTabId(tabId);
-    const candidates = direct
-      ? direct.acceptingNavigation
-        ? [direct]
-        : []
-      : [...recordings.values()].filter(
-          (recording) => !recording.settled && recording.acceptingNavigation,
+    const candidates = [...recordings.values()].filter(
+      (recording) =>
+        !recording.settled && recording.acceptingNavigation && recording.tabs.activeTabId === tabId,
+    );
+    for (const recording of candidates) {
+      const queued = enqueueRecordingAction(recording, async () => {
+        if (tabId !== recording.tabs.currentTabId) {
+          await activateRecordingTab(recording, tabId);
+        }
+        const result = observeRecordedNavigation(
+          stepBufferFor(recording, tabId, url),
+          url,
+          causedByAction,
+          transitionType,
+          transitionQualifiers,
         );
-    if (candidates.length === 0) return;
-
-    let resolveTracked!: () => void;
-    const tracked = new Promise<void>((resolve) => {
-      resolveTracked = resolve;
-    });
-    for (const candidate of candidates) candidate.navigationCallbacks.add(tracked);
-
-    void (async () => {
-      try {
-        const recording = await findRecordingForTab(tabId, deps);
-        if (!recording || !recording.acceptingNavigation || !candidates.includes(recording)) {
+        if (result.kind === "coalesce_redirect") {
+          recording.observation?.scheduleRedirect(tabId, recording.steps, result.url);
           return;
         }
-        enqueueRecordingAction(recording, async () => {
-          const result = observeRecordedNavigation(
-            recording,
-            url,
-            causedByAction,
-            transitionType,
-            transitionQualifiers,
-          );
-          if (result.kind === "coalesce_redirect") {
-            recording.observation?.scheduleRedirect(tabId, recording.steps, result.url);
-            return;
-          }
 
-          if (result.kind === "noop") return;
-          recording.observation?.clearRedirect(tabId);
-          if (result.kind === "appended") {
-            await processRecordedStep(recording, result.index, tabId);
-          } else {
-            recording.observation?.scheduleSettle(tabId, recording.steps, result.index);
-          }
-        });
-      } finally {
-        for (const candidate of candidates) candidate.navigationCallbacks.delete(tracked);
-        resolveTracked();
-      }
-    })();
+        if (result.kind === "noop") return;
+        recording.observation?.clearRedirect(tabId);
+        if (result.kind === "appended") {
+          await processRecordedStep(recording, result.index, tabId);
+        } else {
+          recording.observation?.scheduleSettle(tabId, recording.steps, result.index);
+        }
+      });
+      const tracked = queued.catch(() => {});
+      recording.navigationCallbacks.add(tracked);
+      void tracked.finally(() => recording.navigationCallbacks.delete(tracked));
+    }
   };
   const onMainFrameComplete = (tabId: number, url?: string) => {
     void (async () => {
@@ -651,7 +741,8 @@ export function attachRecordQueryListener(deps: RecordDeps = getDefaultDeps()):
         sendResponse({ active: false });
         return;
       }
-      await rearmRecording(recording, tabId, deps);
+      const activation = sender.tab?.active ? recording.tabs.noteActivation(tabId) : undefined;
+      await rearmRecording(recording, tabId, deps, activation);
       sendResponse({
         active: true,
         requestId: recording.requestId,
@@ -716,7 +807,7 @@ async function finishRecordingAttempt(
   if (!(await drainRecordingToStability(recording))) {
     return null;
   }
-  await recording.observation?.settleTrailing(recording.tabId, recording.steps);
+  await recording.observation?.settleTrailing(recording.tabs.currentTabId, recording.steps);
 
   recording.settled = true;
   recordings.delete(sessionId);
@@ -768,7 +859,7 @@ export async function handleRecordStart(
   const redactValues = params.redact_values ?? false;
   recordings.set(params.session_id, {
     requestId,
-    tabId: target.tabId,
+    tabs: new RecordingTabCoordinator(target.tabId, navigateUrl),
     agentWindowId: ctx.agentWindowId,
     startUrl: navigateUrl,
     ...(params.purpose ? { purpose: params.purpose } : {}),
@@ -776,14 +867,12 @@ export async function handleRecordStart(
     startedAt: new Date(startedAtMs).toISOString(),
     startedAtMs,
     traceVersion: traceVersionOrErr,
+    supportsTabSwitchSteps: params.supports_tab_switch_steps === true,
     finishPromise,
     resolveFinish,
     rejectFinish,
     settled: false,
     finishAttempt: null,
-    currentUrl: navigateUrl,
-    pendingNavigation: false,
-    pendingNavigationDeadline: undefined,
     observation:
       traceVersionOrErr === 3 && deps.cdp
         ? new RecordingObservationRuntime({
@@ -799,12 +888,23 @@ export async function handleRecordStart(
     actionQueue: Promise.resolve(),
     lastStepSequenceByProducer: new Map(),
   });
+  deps.frameCoordinator?.begin(requestId, startedAtMs, target.tabId, async (scope) => {
+    const recording = recordings.get(params.session_id);
+    if (!recording || recording.requestId !== requestId || recording.settled) return;
+    try {
+      await recording.observation?.refreshDocument(scope.tabId, scope.producerId);
+    } catch {
+      // The normal action-time capture remains available if a child Document
+      // is replaced while its readiness refresh is in flight.
+    }
+  });
   // Observe navigations for the whole recording lifetime; attach before
   // optional navigate so the destination load can rearm capture.
   ensureBrowserObservationListeners(deps);
 
   const abortPending = async (notifyContent: boolean) => {
     recordings.get(params.session_id)?.observation?.cancel();
+    deps.frameCoordinator?.cancel(requestId);
     recordings.delete(params.session_id);
     releaseBrowserObservationListenersIfIdle();
     if (notifyContent) {
@@ -886,7 +986,7 @@ export async function handleRecordStart(
     return cancelledError();
   }
   active.startUrl = startUrl;
-  active.currentUrl = startUrl;
+  active.tabs.navigation(target.tabId, startUrl).currentUrl = startUrl;
 
   if (isContentScriptRestrictedUrl(startUrl)) {
     await abortPending(false);
@@ -921,6 +1021,10 @@ export async function handleRecordStart(
   const startMsg: RecordStartMessage = { type: RECORD_START, requestId, startedAtMs };
 
   try {
+    if (deps.frameCoordinator) {
+      const frameStarted = await deps.frameCoordinator.armTab(requestId, target.tabId);
+      if (!frameStarted) throw new Error("top recording document did not start");
+    }
     await sendRecordStartWithAck(target.tabId, startMsg, deps.sendToTab);
   } catch {
     await abortPending(true);
@@ -1040,6 +1144,7 @@ export function clearRecordingForSession(sessionId: string): void {
   }
   void clearRearmTimersForRecording(recording, getDefaultDeps());
   if (!recording.settled) {
+    getDefaultDeps().frameCoordinator?.cancel(recording.requestId);
     recording.observation?.cancel();
     recording.settled = true;
     recording.rejectFinish(new Error("recording cleared"));

apps/extension/src/tools/snapshot-ref.ts

@@ -2,8 +2,9 @@
 // compound CDP node identity via the session RefStore, and build stable
 // `ref_not_found` errors for hard-failure tool paths.
 
+import type { Rect } from "@browser-skill/vom";
 import type { SessionContext } from "@/session-manager/manager";
-import { normaliseRef } from "@/session-manager/ref-store";
+import { normaliseRef, type RefCapability, type RefTargetKind } from "@/session-manager/ref-store";
 import type { RpcError } from "@/transport/types";
 import { rpcError } from "./errors";
 
@@ -12,6 +13,9 @@ export interface SnapshotRefLookup {
   refKey: string;
   frameId?: string;
   cdpSessionId?: string;
+  visibleRect?: Rect;
+  kind: RefTargetKind;
+  capabilities: RefCapability[];
 }
 
 function refEntryForTab(ctx: SessionContext, refKey: string, tabId: number) {
@@ -37,6 +41,9 @@ export function lookupSnapshotRef(
     refKey,
     ...(entry.frameId ? { frameId: entry.frameId } : {}),
     ...(entry.cdpSessionId ? { cdpSessionId: entry.cdpSessionId } : {}),
+    ...(entry.visibleRect ? { visibleRect: entry.visibleRect } : {}),
+    kind: entry.kind,
+    capabilities: entry.capabilities,
   };
 }
 
@@ -49,6 +56,7 @@ export function resolveSnapshotRef(
   ctx: SessionContext,
   ref: string,
   tabId: number,
+  requiredCapability?: RefCapability,
 ): SnapshotRefLookup | RpcError {
   const looked = lookupSnapshotRef(ctx, ref, tabId);
   if (looked === null) {
@@ -58,5 +66,13 @@ export function resolveSnapshotRef(
       `ref ${ref} unknown for tab ${tabId} in session ${ctx.sessionId}`,
     );
   }
+  if (requiredCapability && !looked.capabilities.includes(requiredCapability)) {
+    return rpcError(
+      "permission_denied",
+      "ref_capability_denied",
+      `ref ${ref} does not support ${requiredCapability}`,
+      { ref: looked.refKey, required_capability: requiredCapability, kind: looked.kind },
+    );
+  }
   return looked;
 }

apps/extension/src/tools/vom/__tests__/capture.test.ts

@@ -36,7 +36,7 @@ function fakeSnapshotReply() {
         },
         layout: {
           nodeIndex: [1, 2, 3],
-          // styles columns follow requested computedStyles order: [position, pointer-events]
+          // Legacy fixture: omitted style columns fall back to visible defaults.
           styles: [
             [i("static"), i("auto")],
             [i("fixed"), i("auto")],
@@ -682,6 +682,84 @@ describe("captureViewModel", () => {
     expect(nodes.find((n) => n.backendNodeId === 11)?.cursor).toBe("auto");
   });
 
+  it("captures painted visibility as DOM fallback evidence", async () => {
+    const S = ["html", "body", "button", "static", "auto", "visible", "hidden", "1", "0"];
+    const i = (value: string) => S.indexOf(value);
+    const snapshot = {
+      strings: S,
+      documents: [
+        {
+          nodes: {
+            parentIndex: [-1, 0, 1, 1, 1],
+            nodeName: [i("html"), i("body"), i("button"), i("button"), i("button")],
+            backendNodeId: [10, 11, 12, 13, 14],
+            attributes: [[], [], [], [], []],
+          },
+          layout: {
+            nodeIndex: [1, 2, 3, 4],
+            styles: [
+              [i("static"), i("auto"), i("auto"), i("visible"), i("1")],
+              [i("static"), i("auto"), i("auto"), i("visible"), i("1")],
+              [i("static"), i("auto"), i("auto"), i("hidden"), i("1")],
+              [i("static"), i("auto"), i("auto"), i("visible"), i("0")],
+            ],
+            bounds: [
+              [0, 0, 1000, 800],
+              [10, 10, 100, 30],
+              [10, 50, 100, 30],
+              [10, 90, 100, 30],
+            ],
+            paintOrders: [0, 1, 2, 3],
+          },
+        },
+      ],
+    };
+
+    const { nodes } = await captureViewModel(makeCdp(snapshot), 4);
+
+    expect(nodes.find((node) => node.backendNodeId === 12)?.rendered).toBe(true);
+    expect(nodes.find((node) => node.backendNodeId === 13)?.rendered).toBe(false);
+    expect(nodes.find((node) => node.backendNodeId === 14)?.rendered).toBe(false);
+  });
+
+  it("propagates fully transparent ancestor suppression to painted descendants", async () => {
+    const S = ["html", "body", "div", "canvas", "static", "auto", "visible", "1", "0"];
+    const i = (value: string) => S.indexOf(value);
+    const snapshot = {
+      strings: S,
+      documents: [
+        {
+          nodes: {
+            parentIndex: [-1, 0, 1, 2],
+            nodeName: [i("html"), i("body"), i("div"), i("canvas")],
+            backendNodeId: [10, 11, 12, 13],
+            attributes: [[], [], [], []],
+          },
+          layout: {
+            nodeIndex: [1, 2, 3],
+            styles: [
+              [i("static"), i("auto"), i("auto"), i("visible"), i("1")],
+              [i("static"), i("auto"), i("auto"), i("visible"), i("0")],
+              [i("static"), i("auto"), i("auto"), i("visible"), i("1")],
+            ],
+            bounds: [
+              [0, 0, 1000, 800],
+              [10, 10, 200, 100],
+              [10, 10, 200, 100],
+            ],
+            paintOrders: [0, 1, 2],
+          },
+        },
+      ],
+    };
+
+    const { nodes } = await captureViewModel(makeCdp(snapshot), 4);
+    const canvas = nodes.find((node) => node.backendNodeId === 13);
+
+    expect(canvas?.rendered).toBe(true);
+    expect(canvas?.visuallySuppressed).toBe(true);
+  });
+
   it("subtracts scroll offset to make rects viewport-relative", async () => {
     const cdp = {
       send: vi.fn(async (_t: number, method: string) => {

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

@@ -132,4 +132,67 @@ describe("captureFrameData", () => {
       ]),
     );
   });
+
+  it("keeps OOPIF semantics when viewport projection is unavailable", async () => {
+    const owner = { ...ownerNode(10, 50), rect: null, localRect: null };
+    const captured: CapturedViewModel = {
+      nodes: [owner],
+      viewport: { width: 1000, height: 800 },
+      iframeNodes: new Map(),
+      frameNodes: new Map([["main", [owner]]]),
+      rootFrameId: "main",
+      excludedBackendNodeIds: new Set(),
+    };
+    const cdp: CdpRunner = {
+      send: vi.fn(async (_tabId, method) => {
+        if (method === "Accessibility.enable") return {};
+        if (method === "Accessibility.getFullAXTree") return { nodes: [] };
+        if (method === "DOM.getBoxModel") throw new Error("owner geometry unavailable");
+        if (method === "Page.getLayoutMetrics") {
+          return { cssLayoutViewport: { clientWidth: 1000, clientHeight: 800 } };
+        }
+        throw new Error(`unexpected root ${method}`);
+      }) as CdpRunner["send"],
+      sendToTarget: vi.fn(async (_target, method) => {
+        if (method === "Page.getLayoutMetrics") throw new Error("viewport unavailable");
+        if (method === "DOMSnapshot.enable" || method === "Accessibility.enable") return {};
+        if (method === "DOMSnapshot.captureSnapshot") return childSnapshot("child", 101);
+        if (method === "Accessibility.getFullAXTree") {
+          return {
+            nodes: [
+              {
+                nodeId: "button",
+                backendDOMNodeId: 101,
+                role: { type: "role", value: "button" },
+                name: { type: "computedString", value: "Continue" },
+              },
+            ],
+          };
+        }
+        throw new Error(`unexpected ${method}`);
+      }) as unknown as NonNullable<CdpRunner["sendToTarget"]>,
+      getFrameGraph: vi.fn(async () => ({
+        rootFrameId: "main",
+        frames: [
+          { frameId: "main", target: { tabId: 4 } },
+          {
+            frameId: "child",
+            parentFrameId: "main",
+            ownerBackendNodeId: 10,
+            target: { tabId: 4, sessionId: "child-session" },
+          },
+        ],
+      })),
+    };
+
+    const documents = await captureFrameData(cdp, 4, captured);
+    const childDocument = documents.find((document) => document.frameId === "child");
+
+    expect(childDocument?.axNodes).toEqual([
+      expect.objectContaining({ backendDOMNodeId: 101, frameId: "child" }),
+    ]);
+    expect(childDocument?.domNodes.find((node) => node.backendNodeId === 101)).toEqual(
+      expect.objectContaining({ rect: null, localRect: { x: 10, y: 20, w: 100, h: 40 } }),
+    );
+  });
 });

apps/extension/src/tools/vom/__tests__/name-enrichment.test.ts

@@ -0,0 +1,183 @@
+import { describe, expect, it, vi } from "vitest";
+import type { CdpTarget } from "@/browser-driver/frame-graph";
+import type { CdpRunner } from "../../shared";
+import type { CapturedNode } from "../capture";
+import type { FrameDocument, FrameOwnedAxNode } from "../frame-document";
+import { probeTooltipNames } from "../name-enrichment";
+import { buildSemanticGraph, resolveSemanticGraph } from "../semantic-graph";
+import { stableIdentifierName } from "../semantic-graph/name-evidence";
+import { frameBackendKey } from "../semantic-graph/types";
+
+function document(
+  target: CdpTarget,
+  backendNodeId: number,
+  accessibleName?: string,
+  frameId = "child",
+  x = 10,
+): FrameDocument<FrameOwnedAxNode> {
+  const node: CapturedNode = {
+    backendNodeId,
+    parentBackendNodeId: null,
+    frameId,
+    tag: "button",
+    attrs: {
+      id: "toolInsertRecord",
+      "data-test-id": "toolInsertRecord",
+      ...(accessibleName ? { "aria-label": accessibleName } : {}),
+    },
+    rect: { x, y: 20, w: 40, h: 30 },
+    localRect: { x: 2, y: 3, w: 40, h: 30 },
+    paintOrder: 1,
+    position: "static",
+    pointerEvents: "auto",
+    cursor: "pointer",
+  };
+  return {
+    frameId,
+    parentFrameId: "main",
+    contextScopeId: "child",
+    target,
+    axNodes: [],
+    domNodes: [node],
+    url: "https://example.com/frame",
+  };
+}
+
+function semantics(documents: FrameDocument<FrameOwnedAxNode>[]) {
+  return resolveSemanticGraph(
+    buildSemanticGraph({
+      documents,
+      viewport: { width: 800, height: 600 },
+      rootFrameId: documents[0]?.frameId,
+    }),
+    { identifierFallback: false },
+  );
+}
+
+describe("tooltip name enrichment", () => {
+  it("uses the owning frame target and upgrades an identifier name from a tooltip", async () => {
+    const target = { tabId: 7, sessionId: "oopif-session" };
+    let hovered = false;
+    const cdp: CdpRunner = {
+      send: vi.fn(async (_tabId, method, params) => {
+        if (method === "Input.dispatchMouseEvent") {
+          hovered = (params as { x?: number }).x === 30;
+        }
+        return {};
+      }) as CdpRunner["send"],
+      sendToTarget: vi.fn(async (_target, method) => {
+        if (method === "Page.createIsolatedWorld") return { executionContextId: 11 };
+        if (method === "DOM.resolveNode") return { object: { objectId: "button-501" } };
+        if (method === "Runtime.callFunctionOn") {
+          return { result: { value: hovered ? ["插入行"] : [] } };
+        }
+        return {};
+      }) as CdpRunner["sendToTarget"],
+    };
+
+    const documents = [document(target, 501)];
+    const graph = semantics(documents);
+    const names = await probeTooltipNames(cdp, 7, documents, graph);
+
+    expect(names.get(frameBackendKey("child", 501))).toBe("插入行");
+    expect(cdp.sendToTarget).toHaveBeenCalledWith(
+      target,
+      "Page.createIsolatedWorld",
+      expect.objectContaining({ frameId: "child" }),
+    );
+
+    const sendsBeforeCache = vi.mocked(cdp.send).mock.calls.length;
+    const targetSendsBeforeCache = vi.mocked(
+      cdp.sendToTarget as NonNullable<CdpRunner["sendToTarget"]>,
+    ).mock.calls.length;
+    const cached = await probeTooltipNames(cdp, 7, documents, graph);
+    expect(cached.get(frameBackendKey("child", 501))).toBe("插入行");
+    expect(cdp.send).toHaveBeenCalledTimes(sendsBeforeCache);
+    expect(cdp.sendToTarget).toHaveBeenCalledTimes(targetSendsBeforeCache);
+  });
+
+  it("does not probe controls that already have a higher-confidence name", async () => {
+    const cdp: CdpRunner = {
+      send: vi.fn(async () => ({})) as CdpRunner["send"],
+      sendToTarget: vi.fn(async () => ({ executionContextId: 12 })) as CdpRunner["sendToTarget"],
+    };
+
+    const documents = [document({ tabId: 8 }, 601, "Add a new record")];
+    const names = await probeTooltipNames(cdp, 8, documents, semantics(documents));
+
+    expect(names.size).toBe(0);
+    expect(cdp.send).not.toHaveBeenCalled();
+    expect(cdp.sendToTarget).not.toHaveBeenCalled();
+  });
+
+  it("does not collect supplemental names from form controls", async () => {
+    const cdp: CdpRunner = {
+      send: vi.fn(async () => ({})) as CdpRunner["send"],
+      sendToTarget: vi.fn(async () => ({ executionContextId: 12 })) as CdpRunner["sendToTarget"],
+    };
+    const inputDocument = document({ tabId: 8 }, 602);
+    inputDocument.domNodes[0] = {
+      ...inputDocument.domNodes[0],
+      tag: "input",
+      attrs: { type: "email" },
+      formValue: "user@example.com",
+      formDefaultValue: "",
+      formState: "filled",
+    };
+
+    const names = await probeTooltipNames(cdp, 8, [inputDocument], semantics([inputDocument]));
+
+    expect(names.size).toBe(0);
+    expect(cdp.send).not.toHaveBeenCalled();
+    expect(cdp.sendToTarget).not.toHaveBeenCalled();
+  });
+
+  it("keeps tooltip evidence isolated across sibling frame sessions", async () => {
+    let hoveredX = -10;
+    const cdp: CdpRunner = {
+      send: vi.fn(async (_tabId, method, params) => {
+        if (method === "Input.dispatchMouseEvent") {
+          hoveredX = (params as { x: number }).x;
+        }
+        return {};
+      }) as CdpRunner["send"],
+      sendToTarget: vi.fn(async (target, method, params) => {
+        if (method === "Page.createIsolatedWorld") {
+          return { executionContextId: target.sessionId === "left-session" ? 21 : 22 };
+        }
+        if (method === "DOM.resolveNode") {
+          return { object: { objectId: target.sessionId === "left-session" ? "left" : "right" } };
+        }
+        if (method === "Runtime.callFunctionOn") {
+          const objectId = (params as { objectId: string }).objectId;
+          const value =
+            objectId === "left" && hoveredX === 30
+              ? ["Left action"]
+              : objectId === "right" && hoveredX === 130
+                ? ["Right action"]
+                : [];
+          return { result: { value } };
+        }
+        return {};
+      }) as CdpRunner["sendToTarget"],
+    };
+    const documents = [
+      document({ tabId: 9, sessionId: "left-session" }, 701, undefined, "left", 10),
+      document({ tabId: 9, sessionId: "right-session" }, 701, undefined, "right", 110),
+    ];
+
+    const names = await probeTooltipNames(cdp, 9, documents, semantics(documents));
+
+    expect(names.get(frameBackendKey("left", 701))).toBe("Left action");
+    expect(names.get(frameBackendKey("right", 701))).toBe("Right action");
+  });
+});
+
+describe("stable identifier evidence", () => {
+  it("accepts readable action identifiers and rejects framework-generated ids", () => {
+    expect(stableIdentifierName({ id: "toolInsertRecord" })).toBe("Insert record");
+    expect(stableIdentifierName({ id: "reactivateAccount" })).toBe("Reactivate account");
+    expect(stableIdentifierName({ id: "headlessui-menu-button-r1" })).toBeUndefined();
+    expect(stableIdentifierName({ id: "7f15a3bc91" })).toBeUndefined();
+  });
+});

apps/extension/src/tools/vom/__tests__/record-safe-observation.test.ts

@@ -0,0 +1,82 @@
+import { describe, expect, it } from "vitest";
+import {
+  RECORD_DOCUMENT_ATTRIBUTE,
+  recordingDocumentMarkerValue,
+} from "@/shared/recording-document-identity";
+import { projectRecordSafeObservation } from "../record-safe-observation";
+
+describe("projectRecordSafeObservation", () => {
+  it("projects the opaque recording identity without exposing captured attributes", () => {
+    const recordingDocumentId = "123e4567-e89b-42d3-a456-426614174000";
+    const result = projectRecordSafeObservation({
+      rootFrameId: "child",
+      frameDocuments: [
+        {
+          frameId: "child",
+          target: { tabId: 4, sessionId: "oopif-session" },
+          contextScopeId: "scope-1",
+          axNodes: [],
+          domNodes: [
+            {
+              backendNodeId: 1,
+              parentBackendNodeId: null,
+              tag: "html",
+              attrs: {
+                [RECORD_DOCUMENT_ATTRIBUTE]: recordingDocumentMarkerValue(recordingDocumentId),
+                value: "user@example.com",
+              },
+              rect: null,
+              paintOrder: 0,
+              position: "static",
+              pointerEvents: "auto",
+            },
+          ],
+        },
+      ],
+      rendered: { text: '@vom 1\nRootWebArea "Example"', refs: [], truncated: false },
+    });
+
+    expect(result.frames).toEqual([
+      {
+        frameId: "child",
+        target: { tabId: 4, sessionId: "oopif-session" },
+        recordingDocumentId,
+      },
+    ]);
+    const dumped = JSON.stringify(result);
+    expect(dumped).not.toContain("user@example.com");
+    expect(dumped).not.toContain("attrs");
+    expect(dumped).not.toContain("domNodes");
+    expect(dumped).not.toContain("axNodes");
+  });
+
+  it("does not project a page-controlled marker value as recording identity", () => {
+    const result = projectRecordSafeObservation({
+      rootFrameId: "root",
+      frameDocuments: [
+        {
+          frameId: "root",
+          target: { tabId: 4 },
+          contextScopeId: "scope-1",
+          axNodes: [],
+          domNodes: [
+            {
+              backendNodeId: 1,
+              parentBackendNodeId: null,
+              tag: "html",
+              attrs: { [RECORD_DOCUMENT_ATTRIBUTE]: "bsk:user@example.com" },
+              rect: null,
+              paintOrder: 0,
+              position: "static",
+              pointerEvents: "auto",
+            },
+          ],
+        },
+      ],
+      rendered: { text: '@vom 1\nRootWebArea "Example"', refs: [], truncated: false },
+    });
+
+    expect(result.frames).toEqual([{ frameId: "root", target: { tabId: 4 } }]);
+    expect(JSON.stringify(result)).not.toContain("user@example.com");
+  });
+});

apps/extension/src/tools/vom/__tests__/rendered-surfaces.test.ts

@@ -0,0 +1,256 @@
+import type { VomScene } from "@browser-skill/vom";
+import { describe, expect, it } from "vitest";
+import type { CapturedNode } from "../capture";
+import type { CapturedFrameDocument } from "../frame-capture";
+import {
+  clusterRenderedSurfaces,
+  discoverRenderedSurfaces,
+  projectRenderedSurfaces,
+} from "../rendered-surfaces";
+import type { SemanticAxNode } from "../semantic-graph";
+
+function domNode(backendNodeId: number, overrides: Partial<CapturedNode> = {}): CapturedNode {
+  return {
+    backendNodeId,
+    parentBackendNodeId: null,
+    frameId: "main",
+    ownerFrameBackendNodeId: null,
+    tag: "canvas",
+    attrs: {},
+    rect: { x: 10, y: 20, w: 800, h: 500 },
+    localRect: { x: 10, y: 20, w: 800, h: 500 },
+    paintOrder: 1,
+    position: "static",
+    pointerEvents: "auto",
+    rendered: true,
+    ...overrides,
+  };
+}
+
+function document(
+  domNodes: CapturedNode[],
+  axNodes: SemanticAxNode[] = [],
+): CapturedFrameDocument<SemanticAxNode> {
+  return {
+    frameId: domNodes[0]?.frameId ?? "main",
+    contextScopeId: domNodes[0]?.frameId ?? "main",
+    target: { tabId: 4 },
+    domNodes,
+    axNodes,
+  };
+}
+
+describe("rendered surface discovery", () => {
+  it("finds prominent rendered canvases and excludes hidden descendants", () => {
+    const visible = domNode(2, { parentBackendNodeId: 1 });
+    const hidden = domNode(3, { parentBackendNodeId: 4 });
+    const surfaces = discoverRenderedSurfaces(
+      [
+        document([
+          domNode(1, { tag: "main", rect: null, localRect: null }),
+          visible,
+          domNode(4, { tag: "section", attrs: { "aria-hidden": "true" }, rect: null }),
+          hidden,
+        ]),
+      ],
+      { width: 1280, height: 720 },
+    );
+
+    expect(surfaces).toHaveLength(1);
+    expect(surfaces[0]).toMatchObject({ backendNodeId: 2 });
+  });
+
+  it("keeps tiny canvases as individually addressable exact discoveries", () => {
+    const surfaces = discoverRenderedSurfaces(
+      [document([domNode(2, { rect: { x: 1, y: 1, w: 8, h: 8 } })])],
+      { width: 1280, height: 720 },
+    );
+    expect(surfaces).toEqual([expect.objectContaining({ backendNodeId: 2 })]);
+  });
+
+  it("keeps a surface when the canvas only has partial native accessibility content", () => {
+    const axNodes = [
+      {
+        nodeId: "canvas",
+        backendDOMNodeId: 2,
+        role: { type: "role", value: "presentation" },
+        childIds: ["button"],
+        frameId: "main",
+      },
+      {
+        nodeId: "button",
+        backendDOMNodeId: 3,
+        role: { type: "role", value: "button" },
+        frameId: "main",
+      },
+    ] as SemanticAxNode[];
+    expect(
+      discoverRenderedSurfaces([document([domNode(2)], axNodes)], { width: 1280, height: 720 }),
+    ).toEqual([expect.objectContaining({ backendNodeId: 2 })]);
+  });
+
+  it("discovers unnamed canvases without guessing labels from engineering attributes", () => {
+    const canvas = domNode(2, {
+      attrs: {
+        id: "must-not-be-a-label",
+        class: "must-not-be-a-label",
+        "data-testid": "must-not-be-a-label",
+      },
+    });
+
+    expect(discoverRenderedSurfaces([document([canvas])], { width: 1280, height: 720 })).toEqual([
+      expect.not.objectContaining({
+        label: expect.anything(),
+      }),
+    ]);
+  });
+
+  it("treats blank explicit Canvas names as unnamed", () => {
+    expect(
+      discoverRenderedSurfaces(
+        [document([domNode(2, { attrs: { "aria-label": "   ", title: "\n\t" } })])],
+        { width: 1280, height: 720 },
+      ),
+    ).toEqual([expect.not.objectContaining({ label: expect.anything() })]);
+  });
+
+  it("excludes canvases inside BrowserSkill-owned DOM subtrees", () => {
+    const owner = domNode(1, { tag: "div", rect: null, localRect: null });
+    const canvas = domNode(2, { parentBackendNodeId: 1 });
+
+    expect(
+      discoverRenderedSurfaces(
+        [document([owner, canvas])],
+        { width: 1280, height: 720 },
+        new Set([1]),
+      ),
+    ).toEqual([]);
+  });
+
+  it("excludes canvases suppressed by a fully transparent ancestor", () => {
+    const owner = domNode(1, {
+      tag: "div",
+      rect: { x: 0, y: 0, w: 900, h: 600 },
+      visuallySuppressed: true,
+    });
+    const canvas = domNode(2, { parentBackendNodeId: 1 });
+
+    expect(
+      discoverRenderedSurfaces([document([owner, canvas])], { width: 1280, height: 720 }),
+    ).toEqual([]);
+  });
+
+  it("clips canvases to overflow ancestors and drops fully clipped canvases", () => {
+    const owner = domNode(1, {
+      tag: "div",
+      rect: { x: 10, y: 20, w: 100, h: 70 },
+      overflowX: "hidden",
+      overflowY: "hidden",
+    });
+    const partial = domNode(2, {
+      parentBackendNodeId: 1,
+      rect: { x: 55, y: 30, w: 140, h: 60 },
+    });
+    const fullyClipped = domNode(3, {
+      parentBackendNodeId: 1,
+      rect: { x: 140, y: 30, w: 80, h: 50 },
+    });
+
+    expect(
+      discoverRenderedSurfaces([document([owner, partial, fullyClipped])], {
+        width: 1280,
+        height: 720,
+      }),
+    ).toEqual([
+      expect.objectContaining({
+        backendNodeId: 2,
+        visibleRect: { x: 55, y: 30, w: 55, h: 60 },
+      }),
+    ]);
+  });
+});
+
+describe("rendered surface clustering and projection", () => {
+  it("collapses overlapping canvas layers and attaches them to the nearest retained parent", () => {
+    const body = domNode(1, { tag: "body", rect: null, localRect: null });
+    const surfaces = discoverRenderedSurfaces(
+      [
+        document([
+          body,
+          domNode(2, { parentBackendNodeId: 1, paintOrder: 1 }),
+          domNode(3, { parentBackendNodeId: 1, paintOrder: 2 }),
+        ]),
+      ],
+      { width: 1280, height: 720 },
+    );
+    const groups = clusterRenderedSurfaces(surfaces);
+    const scene: VomScene = {
+      viewport: { width: 1280, height: 720 },
+      nodes: [
+        {
+          id: 10,
+          parentId: null,
+          backendNodeId: 1,
+          frameId: "main",
+          tag: "body",
+          role: "RootWebArea",
+          rect: null,
+          paintOrder: 0,
+          position: "static",
+          pointerEvents: "auto",
+        },
+      ],
+    };
+
+    expect(groups).toHaveLength(1);
+    expect(groups[0]?.members).toHaveLength(2);
+    expect(groups[0]?.label).toBeUndefined();
+    expect(
+      projectRenderedSurfaces(
+        scene,
+        [document([body, ...surfaces.map((s) => domNode(s.backendNodeId))])],
+        groups,
+      ),
+    ).toMatchObject({
+      visualSurfaces: [expect.objectContaining({ parentId: 10, backendNodeId: 3, memberCount: 2 })],
+    });
+  });
+
+  it("does not merge a contained canvas with a larger independent canvas", () => {
+    const groups = clusterRenderedSurfaces([
+      ...discoverRenderedSurfaces(
+        [
+          document([
+            domNode(1, { tag: "main", rect: null, localRect: null }),
+            domNode(2, { parentBackendNodeId: 1 }),
+            domNode(3, {
+              parentBackendNodeId: 1,
+              rect: { x: 30, y: 40, w: 200, h: 100 },
+            }),
+          ]),
+        ],
+        { width: 1280, height: 720 },
+      ),
+    ]);
+
+    expect(groups).toHaveLength(2);
+  });
+
+  it("does not merge coincident canvases owned by different containers", () => {
+    const groups = clusterRenderedSurfaces(
+      discoverRenderedSurfaces(
+        [
+          document([
+            domNode(1, { tag: "section", rect: null, localRect: null }),
+            domNode(2, { tag: "section", rect: null, localRect: null }),
+            domNode(3, { parentBackendNodeId: 1 }),
+            domNode(4, { parentBackendNodeId: 2 }),
+          ]),
+        ],
+        { width: 1280, height: 720 },
+      ),
+    );
+
+    expect(groups).toHaveLength(2);
+  });
+});

apps/extension/src/tools/vom/__tests__/semantic-graph.test.ts

@@ -0,0 +1,782 @@
+import { isVomReferenceNode, renderVom } from "@browser-skill/vom";
+import { describe, expect, it } from "vitest";
+import type { CapturedNode } from "../capture";
+import type { FrameDocument } from "../frame-document";
+import { buildSemanticVomScene, type SemanticAxNode } from "../semantic-graph";
+
+function dom(
+  backendNodeId: number,
+  parentBackendNodeId: number | null,
+  tag: string,
+  attrs: Record<string, string> = {},
+  textContent?: string,
+): CapturedNode {
+  return {
+    backendNodeId,
+    parentBackendNodeId,
+    tag,
+    attrs,
+    rect: { x: 0, y: 0, w: 100, h: 30 },
+    paintOrder: backendNodeId,
+    position: "static",
+    pointerEvents: "auto",
+    ...(textContent ? { textContent } : {}),
+  };
+}
+
+function document(
+  frameId: string,
+  axNodes: SemanticAxNode[],
+  domNodes: CapturedNode[],
+  frame?: Pick<FrameDocument<SemanticAxNode>, "parentFrameId" | "ownerBackendNodeId">,
+): FrameDocument<SemanticAxNode> {
+  return {
+    frameId,
+    contextScopeId: frameId,
+    target: { tabId: 1 },
+    axNodes,
+    domNodes,
+    ...frame,
+  };
+}
+
+describe("semantic VOM graph", () => {
+  it("preserves backend-less AX structure without making it referenceable", () => {
+    const scene = buildSemanticVomScene({
+      viewport: { width: 800, height: 600 },
+      rootFrameId: "main",
+      documents: [
+        document(
+          "main",
+          [
+            {
+              nodeId: "root",
+              backendDOMNodeId: 1,
+              role: { type: "role", value: "RootWebArea" },
+              childIds: ["toolbar"],
+            },
+            {
+              nodeId: "toolbar",
+              parentId: "root",
+              role: { type: "role", value: "toolbar" },
+              name: { type: "computedString", value: "Formatting" },
+              childIds: ["bold", "italic"],
+            },
+            {
+              nodeId: "bold",
+              parentId: "toolbar",
+              backendDOMNodeId: 2,
+              role: { type: "role", value: "button" },
+              name: { type: "computedString", value: "Bold" },
+            },
+            {
+              nodeId: "italic",
+              parentId: "toolbar",
+              backendDOMNodeId: 3,
+              role: { type: "role", value: "button" },
+              name: { type: "computedString", value: "Italic" },
+            },
+          ],
+          [dom(1, null, "body"), dom(2, 1, "button"), dom(3, 1, "button")],
+        ),
+      ],
+    });
+
+    const toolbar = scene.nodes.find((node) => node.role === "toolbar");
+    const buttons = scene.nodes.filter((node) => node.role === "button");
+    expect(toolbar).toEqual(expect.objectContaining({ name: "Formatting", referenceable: false }));
+    expect(buttons.map((node) => node.parentId)).toEqual([toolbar?.id, toolbar?.id]);
+    expect(toolbar && isVomReferenceNode(toolbar)).toBe(false);
+    expect(renderVom(scene).refs.map((ref) => ref.backendNodeId)).toEqual([2, 3]);
+  });
+
+  it("resolves missing AX names through one DOM naming pipeline", () => {
+    const scene = buildSemanticVomScene({
+      viewport: { width: 800, height: 600 },
+      rootFrameId: "main",
+      documents: [
+        document(
+          "main",
+          [
+            {
+              nodeId: "root",
+              backendDOMNodeId: 1,
+              role: { type: "role", value: "RootWebArea" },
+              childIds: ["labelled", "titled", "text"],
+            },
+            {
+              nodeId: "labelled",
+              parentId: "root",
+              backendDOMNodeId: 2,
+              role: { type: "role", value: "button" },
+            },
+            {
+              nodeId: "titled",
+              parentId: "root",
+              backendDOMNodeId: 3,
+              role: { type: "role", value: "button" },
+            },
+            {
+              nodeId: "text",
+              parentId: "root",
+              backendDOMNodeId: 4,
+              role: { type: "role", value: "button" },
+            },
+          ],
+          [
+            dom(1, null, "body"),
+            dom(2, 1, "button", { "aria-label": "Add row" }),
+            dom(3, 1, "button", { title: "Settings" }),
+            dom(4, 1, "button"),
+            dom(5, 4, "span", {}, "Save"),
+          ],
+        ),
+      ],
+    });
+
+    expect(scene.nodes.filter((node) => node.role === "button").map((node) => node.name)).toEqual([
+      "Add row",
+      "Settings",
+      "Save",
+    ]);
+  });
+
+  it("aggregates AX text at the semantic text frontier", () => {
+    const scene = buildSemanticVomScene({
+      viewport: { width: 800, height: 600 },
+      rootFrameId: "main",
+      documents: [
+        document(
+          "main",
+          [
+            {
+              nodeId: "root",
+              backendDOMNodeId: 1,
+              role: { type: "role", value: "RootWebArea" },
+              childIds: ["covered", "inline-only", "repeated", "labelled"],
+            },
+            {
+              nodeId: "covered",
+              parentId: "root",
+              backendDOMNodeId: 2,
+              role: { type: "role", value: "paragraph" },
+              childIds: ["covered-static"],
+            },
+            {
+              nodeId: "covered-static",
+              parentId: "covered",
+              role: { type: "role", value: "StaticText" },
+              name: { type: "computedString", value: "Covered text" },
+              childIds: ["covered-inline"],
+            },
+            {
+              nodeId: "covered-inline",
+              parentId: "covered-static",
+              role: { type: "role", value: "InlineTextBox" },
+              name: { type: "computedString", value: "Covered text" },
+            },
+            {
+              nodeId: "inline-only",
+              parentId: "root",
+              backendDOMNodeId: 3,
+              role: { type: "role", value: "paragraph" },
+              childIds: ["inline-leaf"],
+            },
+            {
+              nodeId: "inline-leaf",
+              parentId: "inline-only",
+              role: { type: "role", value: "InlineTextBox" },
+              name: { type: "computedString", value: "Inline fallback" },
+            },
+            {
+              nodeId: "repeated",
+              parentId: "root",
+              backendDOMNodeId: 4,
+              role: { type: "role", value: "paragraph" },
+              childIds: ["first-go", "second-go"],
+            },
+            {
+              nodeId: "first-go",
+              parentId: "repeated",
+              role: { type: "role", value: "StaticText" },
+              name: { type: "computedString", value: "Go" },
+            },
+            {
+              nodeId: "second-go",
+              parentId: "repeated",
+              role: { type: "role", value: "StaticText" },
+              name: { type: "computedString", value: "Go" },
+            },
+            {
+              nodeId: "labelled",
+              parentId: "root",
+              backendDOMNodeId: 5,
+              role: { type: "role", value: "button" },
+              childIds: ["visible-label"],
+            },
+            {
+              nodeId: "visible-label",
+              parentId: "labelled",
+              role: { type: "role", value: "StaticText" },
+              name: { type: "computedString", value: "Visible text" },
+            },
+          ],
+          [
+            dom(1, null, "body"),
+            dom(2, 1, "p"),
+            dom(3, 1, "p"),
+            dom(4, 1, "p"),
+            dom(5, 1, "button", { "aria-label": "Explicit action" }),
+          ],
+        ),
+      ],
+    });
+
+    expect(scene.nodes.find((node) => node.backendNodeId === 2)?.name).toBe("Covered text");
+    expect(scene.nodes.find((node) => node.backendNodeId === 3)?.name).toBe("Inline fallback");
+    expect(scene.nodes.find((node) => node.backendNodeId === 4)?.name).toBe("Go Go");
+    expect(scene.nodes.find((node) => node.backendNodeId === 5)?.name).toBe("Explicit action");
+    expect(renderVom(scene).text).not.toContain("Covered text Covered text");
+  });
+
+  it("uses stable identifiers only as a final name fallback", () => {
+    const base = document(
+      "main",
+      [
+        {
+          nodeId: "root",
+          backendDOMNodeId: 1,
+          role: { type: "role", value: "RootWebArea" },
+          childIds: ["fallback", "labelled", "container"],
+        },
+        {
+          nodeId: "fallback",
+          parentId: "root",
+          backendDOMNodeId: 2,
+          role: { type: "role", value: "button" },
+        },
+        {
+          nodeId: "labelled",
+          parentId: "root",
+          backendDOMNodeId: 3,
+          role: { type: "role", value: "button" },
+          name: { type: "computedString", value: "Localized name" },
+        },
+        {
+          nodeId: "container",
+          parentId: "root",
+          backendDOMNodeId: 4,
+          role: { type: "role", value: "generic" },
+        },
+      ],
+      [
+        dom(1, null, "body"),
+        dom(2, 1, "button", { "data-test-id": "toolInsertRecord" }),
+        dom(3, 1, "button", { id: "toolIgnoredFallback" }),
+        dom(4, 1, "div", { id: "toolbarContainer" }),
+      ],
+    );
+    const staticScene = buildSemanticVomScene({
+      viewport: { width: 800, height: 600 },
+      rootFrameId: "main",
+      documents: [base],
+    });
+    const enrichedScene = buildSemanticVomScene({
+      viewport: { width: 800, height: 600 },
+      rootFrameId: "main",
+      documents: [base],
+      supplementalNames: new Map([["main\u00002", "插入行"]]),
+    });
+
+    expect(staticScene.nodes.find((node) => node.backendNodeId === 2)?.name).toBe("Insert record");
+    expect(staticScene.nodes.find((node) => node.backendNodeId === 3)?.name).toBe("Localized name");
+    expect(staticScene.nodes.find((node) => node.backendNodeId === 4)?.name).toBeUndefined();
+    expect(enrichedScene.nodes.find((node) => node.backendNodeId === 2)?.name).toBe("插入行");
+    expect(enrichedScene.nodes.find((node) => node.backendNodeId === 3)?.name).toBe(
+      "Localized name",
+    );
+  });
+
+  it("isolates equal backend node ids in sibling frames", () => {
+    const scene = buildSemanticVomScene({
+      viewport: { width: 1000, height: 800 },
+      rootFrameId: "main",
+      documents: [
+        document(
+          "main",
+          [
+            {
+              nodeId: "root",
+              backendDOMNodeId: 1,
+              role: { type: "role", value: "RootWebArea" },
+              childIds: ["owner-a", "owner-b"],
+            },
+            {
+              nodeId: "owner-a",
+              parentId: "root",
+              backendDOMNodeId: 10,
+              role: { type: "role", value: "Iframe" },
+            },
+            {
+              nodeId: "owner-b",
+              parentId: "root",
+              backendDOMNodeId: 20,
+              role: { type: "role", value: "Iframe" },
+            },
+          ],
+          [dom(1, null, "body"), dom(10, 1, "iframe"), dom(20, 1, "iframe")],
+        ),
+        document(
+          "frame-a",
+          [
+            {
+              nodeId: "button-a",
+              backendDOMNodeId: 5,
+              role: { type: "role", value: "button" },
+              childIds: ["text-a"],
+            },
+            {
+              nodeId: "text-a",
+              parentId: "button-a",
+              role: { type: "role", value: "StaticText" },
+              name: { type: "computedString", value: "Accept" },
+              childIds: ["inline-a"],
+            },
+            {
+              nodeId: "inline-a",
+              parentId: "text-a",
+              role: { type: "role", value: "InlineTextBox" },
+              name: { type: "computedString", value: "Accept" },
+            },
+          ],
+          [dom(5, null, "button")],
+          { parentFrameId: "main", ownerBackendNodeId: 10 },
+        ),
+        document(
+          "frame-b",
+          [
+            {
+              nodeId: "button-b",
+              backendDOMNodeId: 5,
+              role: { type: "role", value: "button" },
+              childIds: ["text-b"],
+            },
+            {
+              nodeId: "text-b",
+              parentId: "button-b",
+              role: { type: "role", value: "StaticText" },
+              name: { type: "computedString", value: "Decline" },
+              childIds: ["inline-b"],
+            },
+            {
+              nodeId: "inline-b",
+              parentId: "text-b",
+              role: { type: "role", value: "InlineTextBox" },
+              name: { type: "computedString", value: "Decline" },
+            },
+          ],
+          [dom(5, null, "button")],
+          { parentFrameId: "main", ownerBackendNodeId: 20 },
+        ),
+      ],
+    });
+
+    const frameButtons = scene.nodes.filter((node) => node.backendNodeId === 5);
+    const owners = new Map(
+      scene.nodes
+        .filter((node) => node.backendNodeId === 10 || node.backendNodeId === 20)
+        .map((node) => [node.backendNodeId, node.id]),
+    );
+    expect(frameButtons.map((node) => node.frameId)).toEqual(["frame-a", "frame-b"]);
+    expect(frameButtons.map((node) => node.name)).toEqual(["Accept", "Decline"]);
+    expect(frameButtons.map((node) => node.parentId)).toEqual([owners.get(10), owners.get(20)]);
+    expect(renderVom(scene).refs.map((ref) => [ref.frameId, ref.backendNodeId])).toEqual([
+      ["frame-a", 5],
+      ["frame-b", 5],
+    ]);
+  });
+
+  it("requires render evidence before promoting DOM fallback semantics", () => {
+    const hiddenOwner = {
+      ...dom(10, 1, "iframe", { hidden: "" }),
+      rect: null,
+      localRect: null,
+      rendered: false,
+    };
+    const hiddenButton = {
+      ...dom(2, 1, "button", { "aria-label": "Hidden action" }),
+      rendered: false,
+    };
+    const scene = buildSemanticVomScene({
+      viewport: { width: 800, height: 600 },
+      rootFrameId: "main",
+      documents: [
+        document(
+          "main",
+          [
+            {
+              nodeId: "root",
+              backendDOMNodeId: 1,
+              role: { type: "role", value: "RootWebArea" },
+            },
+          ],
+          [dom(1, null, "body"), hiddenButton, hiddenOwner],
+        ),
+        document("hidden-frame", [], [dom(20, null, "button", {}, "Frame action")], {
+          parentFrameId: "main",
+          ownerBackendNodeId: 10,
+        }),
+      ],
+    });
+
+    expect(scene.nodes.some((node) => node.backendNodeId === 2)).toBe(false);
+    expect(scene.nodes.some((node) => node.backendNodeId === 10)).toBe(false);
+    expect(scene.nodes.some((node) => node.frameId === "hidden-frame")).toBe(false);
+    expect(renderVom(scene).refs).toEqual([]);
+  });
+
+  it("retains rendered DOM fallback controls when AX semantics are unavailable", () => {
+    const scene = buildSemanticVomScene({
+      viewport: { width: 800, height: 600 },
+      rootFrameId: "main",
+      documents: [
+        document(
+          "main",
+          [],
+          [dom(1, null, "body"), { ...dom(2, 1, "button", {}, "Save"), rendered: true }],
+        ),
+      ],
+    });
+
+    expect(renderVom(scene).refs).toEqual([
+      expect.objectContaining({ backendNodeId: 2, role: "button", name: "Save" }),
+    ]);
+  });
+
+  it("lets explicit DOM structure override ignored AX metadata", () => {
+    const scene = buildSemanticVomScene({
+      viewport: { width: 800, height: 600 },
+      rootFrameId: "main",
+      documents: [
+        document(
+          "main",
+          [
+            {
+              nodeId: "root",
+              backendDOMNodeId: 1,
+              role: { type: "role", value: "RootWebArea" },
+              childIds: ["toolbar"],
+            },
+            {
+              nodeId: "toolbar",
+              parentId: "root",
+              backendDOMNodeId: 2,
+              ignored: true,
+              role: { type: "role", value: "generic" },
+              childIds: ["wrapper"],
+            },
+            {
+              nodeId: "wrapper",
+              parentId: "toolbar",
+              backendDOMNodeId: 5,
+              role: { type: "role", value: "generic" },
+              childIds: ["bold", "italic"],
+            },
+            {
+              nodeId: "bold",
+              parentId: "wrapper",
+              backendDOMNodeId: 3,
+              role: { type: "role", value: "button" },
+              name: { type: "computedString", value: "Bold" },
+            },
+            {
+              nodeId: "italic",
+              parentId: "wrapper",
+              backendDOMNodeId: 4,
+              role: { type: "role", value: "button" },
+              name: { type: "computedString", value: "Italic" },
+            },
+          ],
+          [
+            dom(1, null, "body"),
+            dom(2, 1, "div", { role: "toolbar" }),
+            dom(5, 2, "div"),
+            dom(3, 5, "button"),
+            dom(4, 5, "button"),
+          ],
+        ),
+      ],
+    });
+
+    const toolbar = scene.nodes.find((node) => node.backendNodeId === 2);
+    const buttons = scene.nodes.filter((node) => [3, 4].includes(node.backendNodeId ?? -1));
+    expect(toolbar).toEqual(expect.objectContaining({ role: "toolbar" }));
+    expect(toolbar && isVomReferenceNode(toolbar)).toBe(false);
+    expect(scene.nodes.some((node) => node.role === "group")).toBe(false);
+    expect(buttons.map((node) => node.parentId)).toEqual([toolbar?.id, toolbar?.id]);
+  });
+
+  it("infers an unnamed group only from independent interaction branches", () => {
+    const scene = buildSemanticVomScene({
+      viewport: { width: 800, height: 600 },
+      rootFrameId: "main",
+      documents: [
+        document(
+          "main",
+          [
+            {
+              nodeId: "root",
+              backendDOMNodeId: 1,
+              role: { type: "role", value: "RootWebArea" },
+              childIds: ["wrapper"],
+            },
+            {
+              nodeId: "wrapper",
+              parentId: "root",
+              backendDOMNodeId: 2,
+              role: { type: "role", value: "generic" },
+              childIds: ["first", "second"],
+            },
+            {
+              nodeId: "first",
+              parentId: "wrapper",
+              backendDOMNodeId: 3,
+              role: { type: "role", value: "button" },
+              name: { type: "computedString", value: "First" },
+            },
+            {
+              nodeId: "second",
+              parentId: "wrapper",
+              backendDOMNodeId: 4,
+              role: { type: "role", value: "button" },
+              name: { type: "computedString", value: "Second" },
+            },
+          ],
+          [dom(1, null, "body"), dom(2, 1, "div"), dom(3, 2, "button"), dom(4, 2, "button")],
+        ),
+      ],
+    });
+
+    const group = scene.nodes.find((node) => node.backendNodeId === 2);
+    const buttons = scene.nodes.filter((node) => [3, 4].includes(node.backendNodeId ?? -1));
+    expect(group).toEqual(expect.objectContaining({ role: "group" }));
+    expect(group?.name).toBeUndefined();
+    expect(group && isVomReferenceNode(group)).toBe(false);
+    expect(buttons.map((node) => node.parentId)).toEqual([group?.id, group?.id]);
+
+    const rendered = renderVom(scene);
+    const lines = rendered.text.split("\n");
+    const groupLine = lines.findIndex((line) => line.trim() === "group");
+    expect(groupLine).toBeGreaterThanOrEqual(0);
+    for (const ref of rendered.refs) {
+      expect(ref.line).toBeGreaterThan(groupLine);
+      expect(lines[ref.line]).toMatch(/^\s+@e\d+ button/);
+    }
+  });
+
+  it("never promotes a form value into its semantic name through supplemental evidence", () => {
+    const secret = "user@example.com";
+    const input = {
+      ...dom(2, 1, "input", { type: "email" }),
+      formValue: secret,
+      formDefaultValue: "",
+      formState: "filled" as const,
+    };
+    const scene = buildSemanticVomScene({
+      viewport: { width: 800, height: 600 },
+      rootFrameId: "main",
+      supplementalNames: new Map([["main\u00002", secret]]),
+      identifierFallback: false,
+      documents: [
+        document(
+          "main",
+          [
+            {
+              nodeId: "root",
+              backendDOMNodeId: 1,
+              role: { type: "role", value: "RootWebArea" },
+              childIds: ["email"],
+            },
+            {
+              nodeId: "email",
+              parentId: "root",
+              backendDOMNodeId: 2,
+              role: { type: "role", value: "textbox" },
+              value: { value: secret },
+            },
+          ],
+          [dom(1, null, "body"), input],
+        ),
+      ],
+    });
+
+    const field = scene.nodes.find((node) => node.backendNodeId === 2);
+    expect(field?.name).toBeUndefined();
+    const rendered = renderVom(scene, { redactValues: true });
+    expect(rendered.text).toContain("•••");
+    expect(JSON.stringify(rendered)).not.toContain(secret);
+  });
+
+  it("keeps uncertain single-branch wrappers flat", () => {
+    const scene = buildSemanticVomScene({
+      viewport: { width: 800, height: 600 },
+      rootFrameId: "main",
+      documents: [
+        document(
+          "main",
+          [
+            {
+              nodeId: "root",
+              backendDOMNodeId: 1,
+              role: { type: "role", value: "RootWebArea" },
+              childIds: ["wrapper"],
+            },
+            {
+              nodeId: "wrapper",
+              parentId: "root",
+              backendDOMNodeId: 2,
+              role: { type: "role", value: "generic" },
+              childIds: ["button"],
+            },
+            {
+              nodeId: "button",
+              parentId: "wrapper",
+              backendDOMNodeId: 3,
+              role: { type: "role", value: "button" },
+              name: { type: "computedString", value: "Only action" },
+            },
+          ],
+          [dom(1, null, "body"), dom(2, 1, "div"), dom(3, 2, "button")],
+        ),
+      ],
+    });
+
+    expect(scene.nodes.some((node) => node.role === "group")).toBe(false);
+    expect(scene.nodes.find((node) => node.backendNodeId === 3)?.parentId).toBe(
+      scene.nodes.find((node) => node.backendNodeId === 1)?.id,
+    );
+  });
+
+  it("does not infer across mixed content boundaries", () => {
+    const scene = buildSemanticVomScene({
+      viewport: { width: 800, height: 600 },
+      rootFrameId: "main",
+      documents: [
+        document(
+          "main",
+          [
+            {
+              nodeId: "root",
+              backendDOMNodeId: 1,
+              role: { type: "role", value: "RootWebArea" },
+              childIds: ["wrapper"],
+            },
+            {
+              nodeId: "wrapper",
+              parentId: "root",
+              backendDOMNodeId: 2,
+              role: { type: "role", value: "generic" },
+              childIds: ["first", "second", "paragraph"],
+            },
+            {
+              nodeId: "first",
+              parentId: "wrapper",
+              backendDOMNodeId: 3,
+              role: { type: "role", value: "button" },
+              name: { type: "computedString", value: "First" },
+            },
+            {
+              nodeId: "second",
+              parentId: "wrapper",
+              backendDOMNodeId: 4,
+              role: { type: "role", value: "button" },
+              name: { type: "computedString", value: "Second" },
+            },
+            {
+              nodeId: "paragraph",
+              parentId: "wrapper",
+              backendDOMNodeId: 5,
+              role: { type: "role", value: "paragraph" },
+            },
+          ],
+          [
+            dom(1, null, "body"),
+            dom(2, 1, "div"),
+            dom(3, 2, "button"),
+            dom(4, 2, "button"),
+            dom(5, 2, "p", {}, "Description"),
+          ],
+        ),
+      ],
+    });
+
+    expect(scene.nodes.some((node) => node.role === "group")).toBe(false);
+  });
+
+  it("keeps only the innermost reliable inferred group", () => {
+    const scene = buildSemanticVomScene({
+      viewport: { width: 800, height: 600 },
+      rootFrameId: "main",
+      documents: [
+        document(
+          "main",
+          [
+            {
+              nodeId: "root",
+              backendDOMNodeId: 1,
+              role: { type: "role", value: "RootWebArea" },
+              childIds: ["outer"],
+            },
+            {
+              nodeId: "outer",
+              parentId: "root",
+              backendDOMNodeId: 2,
+              role: { type: "role", value: "generic" },
+              childIds: ["inner", "third"],
+            },
+            {
+              nodeId: "inner",
+              parentId: "outer",
+              backendDOMNodeId: 3,
+              role: { type: "role", value: "generic" },
+              childIds: ["first", "second"],
+            },
+            {
+              nodeId: "first",
+              parentId: "inner",
+              backendDOMNodeId: 4,
+              role: { type: "role", value: "button" },
+              name: { type: "computedString", value: "First" },
+            },
+            {
+              nodeId: "second",
+              parentId: "inner",
+              backendDOMNodeId: 5,
+              role: { type: "role", value: "button" },
+              name: { type: "computedString", value: "Second" },
+            },
+            {
+              nodeId: "third",
+              parentId: "outer",
+              backendDOMNodeId: 6,
+              role: { type: "role", value: "button" },
+              name: { type: "computedString", value: "Third" },
+            },
+          ],
+          [
+            dom(1, null, "body"),
+            dom(2, 1, "div"),
+            dom(3, 2, "div"),
+            dom(4, 3, "button"),
+            dom(5, 3, "button"),
+            dom(6, 2, "button"),
+          ],
+        ),
+      ],
+    });
+
+    const groups = scene.nodes.filter((node) => node.role === "group");
+    expect(groups.map((node) => node.backendNodeId)).toEqual([3]);
+    expect(scene.nodes.find((node) => node.backendNodeId === 6)?.parentId).not.toBe(groups[0]?.id);
+  });
+});

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

@@ -1,16 +1,25 @@
 // CDP capture adapter: DOMSnapshot.captureSnapshot + Page.getLayoutMetrics
 // → CapturedNode[] + Viewport. This is the ONLY VOM module that touches
 // raw CDP. The captureSnapshot reply is columnar (parallel arrays + a
-// shared string table); we request exactly three computed styles so the
-// `styles` columns are [position, pointer-events, cursor] in that order.
+// shared string table); requested computed styles are decoded through
+// STYLE_COL so capture and visibility policy share one explicit contract.
 
 import type { Rect, Viewport } from "@browser-skill/vom";
 import { evaluateHoverTrigger } from "@/lib/hover-trigger-policy";
 import { isOverlayHostNode, OVERLAY_HOST_SELECTOR } from "../../lib/overlay-bridge";
 import { childFrameProjection, type GeometryProjection, projectRectToViewport } from "../geometry";
 import type { CdpRunner } from "../shared";
+import { clearHover, waitForHover } from "./hover-perception";
 
-const REQUESTED_STYLES = ["position", "pointer-events", "cursor"] as const;
+const REQUESTED_STYLES = [
+  "position",
+  "pointer-events",
+  "cursor",
+  "visibility",
+  "opacity",
+  "overflow-x",
+  "overflow-y",
+] as const;
 const STYLE_COL = Object.fromEntries(
   REQUESTED_STYLES.map((name, index) => [name, index]),
 ) as Record<(typeof REQUESTED_STYLES)[number], number>;
@@ -38,6 +47,16 @@ export interface CapturedNode {
    * `textContent`: the live parser always sets it, hand-built fixtures may not.
    */
   cursor?: string;
+  overflowX?: string;
+  overflowY?: string;
+  /** True when this node or one of its DOM ancestors makes the subtree fully transparent/hidden. */
+  visuallySuppressed?: boolean;
+  /**
+   * Whether the live DOM snapshot provides a painted, non-hidden box for this
+   * node. Semantic resolution uses this only for DOM fallback nodes; AX-backed
+   * nodes remain authoritative even when they are outside the viewport.
+   */
+  rendered?: boolean;
   textContent?: string;
   formState?: "empty" | "filled" | "default";
   formValue?: string;
@@ -460,36 +479,6 @@ function hoverStateExpression(): string {
   })()`;
 }
 
-async function wait(ms: number, signal?: AbortSignal): Promise<void> {
-  throwIfAborted(signal);
-  await new Promise<void>((resolve, reject) => {
-    const timer = setTimeout(() => {
-      signal?.removeEventListener("abort", onAbort);
-      resolve();
-    }, ms);
-    const onAbort = () => {
-      clearTimeout(timer);
-      signal?.removeEventListener("abort", onAbort);
-      reject(captureAbortError());
-    };
-    signal?.addEventListener("abort", onAbort, { once: true });
-  });
-}
-
-async function clearHover(cdp: CdpRunner, tabId: number): Promise<void> {
-  await cdp
-    .send(tabId, "Input.dispatchMouseEvent", {
-      type: "mouseMoved",
-      x: -10,
-      y: -10,
-    })
-    .catch(() =>
-      cdp.send(tabId, "Input.dispatchMouseEvent", { type: "mouseMoved", x: 0, y: 0 }).catch(() => {
-        // best effort
-      }),
-    );
-}
-
 function capturedText(node: CapturedNode): string | undefined {
   const value =
     node.attrs["aria-label"] ?? node.attrs.title ?? node.attrs.alt ?? node.textContent ?? "";
@@ -669,7 +658,7 @@ async function probeHoverSurfaces(
         try {
           await clearHover(cdp, tabId);
           throwIfAborted(options.signal);
-          await wait(HOVER_SETTLE_MS, options.signal);
+          await waitForHover(HOVER_SETTLE_MS, options.signal);
           const baselineReply = await cdp.send<RuntimeEvaluateReply>(tabId, "Runtime.evaluate", {
             expression: hoverStateExpression(),
             returnByValue: true,
@@ -684,7 +673,7 @@ async function probeHoverSurfaces(
             y: candidate.y,
           });
           throwIfAborted(options.signal);
-          await wait(HOVER_SETTLE_MS, options.signal);
+          await waitForHover(HOVER_SETTLE_MS, options.signal);
           const collected = await cdp.send<RuntimeEvaluateReply>(tabId, "Runtime.evaluate", {
             expression: hoverStateExpression(),
             returnByValue: true,
@@ -817,6 +806,10 @@ function parseDocumentNodes(
   const posCol = STYLE_COL.position;
   const peCol = STYLE_COL["pointer-events"];
   const cursorCol = STYLE_COL.cursor;
+  const visibilityCol = STYLE_COL.visibility;
+  const opacityCol = STYLE_COL.opacity;
+  const overflowXCol = STYLE_COL["overflow-x"];
+  const overflowYCol = STYLE_COL["overflow-y"];
   const inputValues = sparseIndexMap(dn.inputValue);
   const textValues = sparseIndexMap(dn.textValue);
   const checkedInputs = new Set(dn.inputChecked?.index ?? []);
@@ -842,6 +835,7 @@ function parseDocumentNodes(
 
   // Build CapturedNodes.
   const nodes: CapturedNode[] = [];
+  const visuallySuppressedByNodeIndex = new Array<boolean>(count).fill(false);
   for (let n = 0; n < count; n++) {
     if (excluded[n]) continue;
     const backendNodeId = dn.backendNodeId[n];
@@ -861,6 +855,11 @@ function parseDocumentNodes(
     let position = "static";
     let pointerEvents = "auto";
     let cursor = "auto";
+    let overflowX = "visible";
+    let overflowY = "visible";
+    let rendered = false;
+    let visuallySuppressed =
+      parentIdx >= 0 ? visuallySuppressedByNodeIndex[parentIdx] === true : false;
     const li = layoutByNode.get(n);
     if (li !== undefined) {
       const b = dl?.bounds?.[li];
@@ -881,7 +880,21 @@ function parseDocumentNodes(
       position = str(strings, styleRow[posCol]) || "static";
       pointerEvents = str(strings, styleRow[peCol]) || "auto";
       cursor = str(strings, styleRow[cursorCol]) || "auto";
+      const visibility = str(strings, styleRow[visibilityCol]) || "visible";
+      const opacity = str(strings, styleRow[opacityCol]) || "1";
+      overflowX = str(strings, styleRow[overflowXCol]) || "visible";
+      overflowY = str(strings, styleRow[overflowYCol]) || "visible";
+      visuallySuppressed ||=
+        visibility === "hidden" ||
+        visibility === "collapse" ||
+        (Number.parseFloat(opacity) || 0) <= 0;
+      rendered =
+        localRect !== null &&
+        visibility !== "hidden" &&
+        visibility !== "collapse" &&
+        (Number.parseFloat(opacity) || 0) > 0;
     }
+    visuallySuppressedByNodeIndex[n] = visuallySuppressed;
 
     // Skip non-element nodes (#text, #cdata-section, etc.) — they carry no
     // geometry and are never queried by callers.
@@ -916,6 +929,10 @@ function parseDocumentNodes(
       position,
       pointerEvents,
       cursor,
+      overflowX,
+      overflowY,
+      visuallySuppressed,
+      rendered,
       textContent,
       ...(formValue !== undefined ? { formValue } : {}),
       ...(tag === "input" || tag === "textarea"
@@ -1020,7 +1037,13 @@ export async function captureViewModel(
   options: CaptureViewModelOptions = {},
 ): Promise<CapturedViewModel> {
   throwIfAborted(options.signal);
-  const metrics = await cdp.send<LayoutMetricsReply>(tabId, "Page.getLayoutMetrics", {});
+  let metrics: LayoutMetricsReply = {};
+  try {
+    metrics = await cdp.send<LayoutMetricsReply>(tabId, "Page.getLayoutMetrics", {});
+  } catch (error) {
+    if (isAbortError(error)) throw error;
+    console.debug("[bsk capture] layout metrics unavailable", error);
+  }
   throwIfAborted(options.signal);
   const dpr = devicePixelRatio(metrics);
   const vpSrc = metrics.cssLayoutViewport ?? metrics.layoutViewport ?? {};

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

@@ -33,25 +33,19 @@ async function discoverFrameGraph(cdp: CdpRunner, tabId: number): Promise<CdpFra
 
 function transformFrameNodes(
   nodes: CapturedNode[],
-  projection: GeometryProjection,
+  projection: GeometryProjection | null,
 ): CapturedNode[] {
   return nodes.map((node) => ({
     ...node,
-    rect: (() => {
-      const bounds = projectRectToViewport(node.rect, projection);
-      return bounds ? { x: bounds.x, y: bounds.y, w: bounds.width, h: bounds.height } : null;
-    })(),
+    rect: projection
+      ? (() => {
+          const bounds = projectRectToViewport(node.rect, projection);
+          return bounds ? { x: bounds.x, y: bounds.y, w: bounds.width, h: bounds.height } : null;
+        })()
+      : null,
   }));
 }
 
-function frameOwnerNode(captured: CapturedViewModel, frame: CdpFrame): CapturedNode | undefined {
-  if (frame.ownerBackendNodeId === undefined) return undefined;
-  const parentNodes = frame.parentFrameId
-    ? captured.frameNodes?.get(frame.parentFrameId)
-    : captured.nodes;
-  return parentNodes?.find((node) => node.backendNodeId === frame.ownerBackendNodeId);
-}
-
 async function captureMissingFrameDocuments(
   cdp: CdpRunner,
   tabId: number,
@@ -65,14 +59,20 @@ async function captureMissingFrameDocuments(
 
   for (const frame of graph.frames) {
     if (!frame.target.sessionId || captured.frameNodes.has(frame.frameId)) continue;
-    const owner = frameOwnerNode(captured, frame);
-    if (!owner?.rect || frame.ownerBackendNodeId === undefined) continue;
     try {
       const child = await captureViewModel(cdpRunnerForTarget(cdp, frame.target), tabId, {
         signal,
       });
-      const projection = await resolveFrameProjection(cdp, graph, frame.frameId);
-      if (!projection) continue;
+      let projection: GeometryProjection | null = null;
+      try {
+        projection = await resolveFrameProjection(cdp, graph, frame.frameId);
+      } catch (err) {
+        if (isAbortError(err)) throw err;
+        console.debug("[bsk observation] child frame geometry projection failed", {
+          frameId: frame.frameId,
+          err,
+        });
+      }
       const rootFrameId = child.rootFrameId ?? frame.frameId;
       const childFrames = child.frameNodes ?? new Map<string, CapturedNode[]>();
       if (!childFrames.has(rootFrameId)) childFrames.set(rootFrameId, child.nodes);
@@ -85,11 +85,13 @@ async function captureMissingFrameDocuments(
       for (const [childFrameId, nodes] of childFrames) {
         captured.frameNodes.set(childFrameId, transformFrameNodes(nodes, projection));
       }
-      captured.iframeNodes.set(
-        frame.ownerBackendNodeId,
-        captured.frameNodes.get(frame.frameId) ?? [],
-      );
-      captured.frameOwnerBackendNodeIds.set(frame.frameId, frame.ownerBackendNodeId);
+      if (frame.ownerBackendNodeId !== undefined) {
+        captured.iframeNodes.set(
+          frame.ownerBackendNodeId,
+          captured.frameNodes.get(frame.frameId) ?? [],
+        );
+        captured.frameOwnerBackendNodeIds.set(frame.frameId, frame.ownerBackendNodeId);
+      }
       if (frame.parentFrameId) captured.frameParentIds.set(frame.frameId, frame.parentFrameId);
       for (const [childFrameId, ownerBackendNodeId] of child.frameOwnerBackendNodeIds ?? []) {
         captured.frameOwnerBackendNodeIds.set(childFrameId, ownerBackendNodeId);

apps/extension/src/tools/vom/hover-perception.ts

@@ -0,0 +1,37 @@
+import type { CdpRunner } from "../shared";
+
+function abortError(): Error {
+  const error = new Error("hover perception aborted");
+  error.name = "AbortError";
+  return error;
+}
+
+export async function waitForHover(ms: number, signal?: AbortSignal): Promise<void> {
+  if (signal?.aborted) throw abortError();
+  await new Promise<void>((resolve, reject) => {
+    const timer = setTimeout(() => {
+      signal?.removeEventListener("abort", onAbort);
+      resolve();
+    }, ms);
+    const onAbort = () => {
+      clearTimeout(timer);
+      signal?.removeEventListener("abort", onAbort);
+      reject(abortError());
+    };
+    signal?.addEventListener("abort", onAbort, { once: true });
+  });
+}
+
+export async function clearHover(cdp: CdpRunner, tabId: number): Promise<void> {
+  await cdp
+    .send(tabId, "Input.dispatchMouseEvent", {
+      type: "mouseMoved",
+      x: -10,
+      y: -10,
+    })
+    .catch(() =>
+      cdp.send(tabId, "Input.dispatchMouseEvent", { type: "mouseMoved", x: 0, y: 0 }).catch(() => {
+        // Best effort cleanup.
+      }),
+    );
+}

apps/extension/src/tools/vom/name-enrichment.ts

@@ -0,0 +1,296 @@
+import { isVomReferenceNode } from "@browser-skill/vom";
+import { type CdpRunner, sendToCdpTarget } from "../shared";
+import type { FrameDocument, FrameOwnedAxNode } from "./frame-document";
+import { clearHover, waitForHover } from "./hover-perception";
+import { stableIdentifierName } from "./semantic-graph/name-evidence";
+import { frameBackendKey, type ResolvedSemanticGraph } from "./semantic-graph/types";
+
+const MAX_TOOLTIP_CANDIDATES = 8;
+const MAX_TOOLTIP_PROBE_MS = 2_400;
+const TOOLTIP_SETTLE_MS = 250;
+const CACHE_TTL_MS = 5 * 60_000;
+const MAX_CACHE_ENTRIES = 500;
+const FORM_CONTROL_TAGS = new Set(["input", "select", "textarea"]);
+
+interface TooltipCacheEntry {
+  name: string;
+  expiresAt: number;
+}
+
+interface TooltipCandidate<T extends FrameOwnedAxNode> {
+  document: FrameDocument<T>;
+  backendNodeId: number;
+  x: number;
+  y: number;
+  stableIdentifier: boolean;
+}
+
+export interface TooltipNameProbeOptions {
+  signal?: AbortSignal;
+  hoverProbeBypassOverlay?: (tabId: number, enabled: boolean) => Promise<void>;
+}
+
+const tooltipCache = new Map<string, TooltipCacheEntry>();
+
+function cacheKey<T extends FrameOwnedAxNode>(
+  document: FrameDocument<T>,
+  backendNodeId: number,
+): string {
+  return `${document.target.tabId}\u0000${document.frameId}\u0000${document.url ?? ""}\u0000${backendNodeId}`;
+}
+
+function cachedName<T extends FrameOwnedAxNode>(
+  document: FrameDocument<T>,
+  backendNodeId: number,
+): string | undefined {
+  const key = cacheKey(document, backendNodeId);
+  const entry = tooltipCache.get(key);
+  if (!entry) return undefined;
+  if (entry.expiresAt <= Date.now()) {
+    tooltipCache.delete(key);
+    return undefined;
+  }
+  return entry.name;
+}
+
+function storeName<T extends FrameOwnedAxNode>(
+  document: FrameDocument<T>,
+  backendNodeId: number,
+  name: string,
+): void {
+  if (tooltipCache.size >= MAX_CACHE_ENTRIES) {
+    const oldest = tooltipCache.keys().next().value;
+    if (oldest !== undefined) tooltipCache.delete(oldest);
+  }
+  tooltipCache.set(cacheKey(document, backendNodeId), {
+    name,
+    expiresAt: Date.now() + CACHE_TTL_MS,
+  });
+}
+
+function tooltipCollectorFunction(): string {
+  return `function() {
+    const ownRoot = this && typeof this.getRootNode === "function" ? this.getRootNode() : null;
+    const roots = ownRoot && ownRoot !== document ? [ownRoot, document] : [document];
+    const items = [];
+    const seen = new Set();
+    for (const root of roots) {
+      for (const el of Array.from(root.querySelectorAll("[role='tooltip']"))) {
+        const style = getComputedStyle(el);
+        const rect = el.getBoundingClientRect();
+        if (rect.width <= 0 || rect.height <= 0) continue;
+        if (style.display === "none" || style.visibility === "hidden" || style.opacity === "0") continue;
+        const text = String(el.getAttribute("aria-label") || el.getAttribute("title") || el.textContent || "")
+          .replace(/\\s+/g, " ")
+          .trim();
+        if (!text || text.length > 160 || seen.has(text)) continue;
+        seen.add(text);
+        items.push(text);
+      }
+    }
+    return items.slice(0, 20);
+  }`;
+}
+
+function cleanTooltipDiff(before: string[], after: string[]): string | undefined {
+  const existing = new Set(before.map((value) => value.toLowerCase()));
+  const added = [...new Set(after.map((value) => value.replace(/\s+/g, " ").trim()))].filter(
+    (value) => value && !existing.has(value.toLowerCase()),
+  );
+  return added.length === 1 ? added[0] : undefined;
+}
+
+function candidates<T extends FrameOwnedAxNode>(
+  documents: FrameDocument<T>[],
+  graph: ResolvedSemanticGraph,
+): TooltipCandidate<T>[] {
+  const documentByFrame = new Map(documents.map((document) => [document.frameId, document]));
+  const byFrame = new Map<string, TooltipCandidate<T>[]>();
+  for (const node of graph.nodes.values()) {
+    if (
+      node.vom.name ||
+      FORM_CONTROL_TAGS.has(node.dom?.tag.toLowerCase() ?? "") ||
+      !node.referenceable ||
+      node.backendNodeId === undefined ||
+      !isVomReferenceNode({
+        ...node.vom,
+        id: 0,
+        parentId: null,
+        backendNodeId: node.backendNodeId,
+        frameId: node.frameId,
+        referenceable: true,
+      })
+    ) {
+      continue;
+    }
+    const document = documentByFrame.get(node.frameId);
+    const rect = node.dom?.rect;
+    if (!document || !rect || rect.w <= 0 || rect.h <= 0) continue;
+    if (
+      rect.x + rect.w <= 0 ||
+      rect.y + rect.h <= 0 ||
+      rect.x >= graph.viewport.width ||
+      rect.y >= graph.viewport.height
+    ) {
+      continue;
+    }
+    if (
+      node.vom.disabled ||
+      node.vom.inert ||
+      node.vom.pointerEvents === "none" ||
+      node.vom.sensitive
+    ) {
+      continue;
+    }
+    const frameCandidates = byFrame.get(node.frameId) ?? [];
+    frameCandidates.push({
+      document,
+      backendNodeId: node.backendNodeId,
+      x: (Math.max(0, rect.x) + Math.min(graph.viewport.width, rect.x + rect.w)) / 2,
+      y: (Math.max(0, rect.y) + Math.min(graph.viewport.height, rect.y + rect.h)) / 2,
+      stableIdentifier: stableIdentifierName(node.dom?.attrs ?? {}) !== undefined,
+    });
+    byFrame.set(node.frameId, frameCandidates);
+  }
+
+  const out: TooltipCandidate<T>[] = [];
+  for (const stableIdentifier of [true, false]) {
+    const queues = documents.map((document) =>
+      (byFrame.get(document.frameId) ?? []).filter(
+        (candidate) => candidate.stableIdentifier === stableIdentifier,
+      ),
+    );
+    for (let index = 0; queues.some((queue) => index < queue.length); index += 1) {
+      for (const queue of queues) {
+        const candidate = queue[index];
+        if (candidate) out.push(candidate);
+      }
+    }
+  }
+  return out;
+}
+
+async function executionContextId<T extends FrameOwnedAxNode>(
+  cdp: CdpRunner,
+  document: FrameDocument<T>,
+): Promise<number | undefined> {
+  const result = await sendToCdpTarget<{ executionContextId?: number }>(
+    cdp,
+    document.target,
+    "Page.createIsolatedWorld",
+    {
+      frameId: document.frameId,
+      worldName: "bsk-vom-tooltip",
+      grantUniveralAccess: false,
+    },
+  );
+  return result.executionContextId;
+}
+
+async function resolvedObjectId<T extends FrameOwnedAxNode>(
+  cdp: CdpRunner,
+  document: FrameDocument<T>,
+  contextId: number,
+  backendNodeId: number,
+): Promise<string | undefined> {
+  const result = await sendToCdpTarget<{
+    object?: { objectId?: string };
+  }>(cdp, document.target, "DOM.resolveNode", {
+    backendNodeId,
+    executionContextId: contextId,
+  });
+  return result.object?.objectId;
+}
+
+async function tooltipTexts<T extends FrameOwnedAxNode>(
+  cdp: CdpRunner,
+  document: FrameDocument<T>,
+  objectId: string,
+): Promise<string[]> {
+  const result = await sendToCdpTarget<{
+    result?: { value?: string[] };
+  }>(cdp, document.target, "Runtime.callFunctionOn", {
+    functionDeclaration: tooltipCollectorFunction(),
+    objectId,
+    returnByValue: true,
+  });
+  return result.result?.value ?? [];
+}
+
+async function releaseObject<T extends FrameOwnedAxNode>(
+  cdp: CdpRunner,
+  document: FrameDocument<T>,
+  objectId: string,
+): Promise<void> {
+  await sendToCdpTarget(cdp, document.target, "Runtime.releaseObject", { objectId }).catch(
+    () => undefined,
+  );
+}
+
+export async function probeTooltipNames<T extends FrameOwnedAxNode>(
+  cdp: CdpRunner,
+  tabId: number,
+  documents: FrameDocument<T>[],
+  graph: ResolvedSemanticGraph,
+  options: TooltipNameProbeOptions = {},
+): Promise<Map<string, string>> {
+  const names = new Map<string, string>();
+  const pending: TooltipCandidate<T>[] = [];
+  for (const candidate of candidates(documents, graph)) {
+    const cached = cachedName(candidate.document, candidate.backendNodeId);
+    if (cached) {
+      names.set(frameBackendKey(candidate.document.frameId, candidate.backendNodeId), cached);
+    } else if (pending.length < MAX_TOOLTIP_CANDIDATES) {
+      pending.push(candidate);
+    }
+  }
+  if (pending.length === 0) return names;
+
+  const started = Date.now();
+  const contexts = new Map<string, number>();
+  await options.hoverProbeBypassOverlay?.(tabId, true).catch(() => undefined);
+  try {
+    for (const candidate of pending) {
+      if (options.signal?.aborted) throw new DOMException("observation aborted", "AbortError");
+      if (Date.now() - started >= MAX_TOOLTIP_PROBE_MS) break;
+      let objectId: string | undefined;
+      try {
+        let contextId = contexts.get(candidate.document.frameId);
+        if (contextId === undefined) {
+          contextId = await executionContextId(cdp, candidate.document);
+          if (contextId === undefined) continue;
+          contexts.set(candidate.document.frameId, contextId);
+        }
+        objectId = await resolvedObjectId(
+          cdp,
+          candidate.document,
+          contextId,
+          candidate.backendNodeId,
+        );
+        if (!objectId) continue;
+        await clearHover(cdp, tabId);
+        const before = await tooltipTexts(cdp, candidate.document, objectId);
+        await cdp.send(tabId, "Input.dispatchMouseEvent", {
+          type: "mouseMoved",
+          x: candidate.x,
+          y: candidate.y,
+        });
+        await waitForHover(TOOLTIP_SETTLE_MS, options.signal);
+        const after = await tooltipTexts(cdp, candidate.document, objectId);
+        const name = cleanTooltipDiff(before, after);
+        if (!name) continue;
+        names.set(frameBackendKey(candidate.document.frameId, candidate.backendNodeId), name);
+        storeName(candidate.document, candidate.backendNodeId, name);
+      } catch (error) {
+        if (error instanceof Error && error.name === "AbortError") throw error;
+      } finally {
+        if (objectId) await releaseObject(cdp, candidate.document, objectId);
+        await clearHover(cdp, tabId);
+      }
+    }
+  } finally {
+    await clearHover(cdp, tabId);
+    await options.hoverProbeBypassOverlay?.(tabId, false).catch(() => undefined);
+  }
+  return names;
+}

apps/extension/src/tools/vom/record-safe-observation.ts

@@ -1,5 +1,6 @@
 import type { Rect, RenderedRef, VomResult } from "@browser-skill/vom";
 import type { CdpTarget } from "@/browser-driver/frame-graph";
+import { readRecordingDocumentIdentity } from "@/shared/recording-document-identity";
 import type { CapturedSurfaceProbe } from "./capture";
 import type { CapturedFrameDocument, FrameAxNode } from "./frame-capture";
 
@@ -9,6 +10,8 @@ export interface CaptureVomFrame {
   target: CdpTarget;
   parentFrameId?: string;
   ownerBackendNodeId?: number;
+  /** BrowserSkill-generated identity for the recording agent in this Document. */
+  recordingDocumentId?: string;
 }
 
 /** Allowlisted geometry used to match a recorded action to a rendered ref. */
@@ -37,14 +40,22 @@ export interface CaptureVomObservationResult {
 }
 
 function projectFrames(documents: CapturedFrameDocument<FrameAxNode>[]): CaptureVomFrame[] {
-  return documents.map((document) => ({
-    frameId: document.frameId,
-    target: document.target,
-    ...(document.parentFrameId ? { parentFrameId: document.parentFrameId } : {}),
-    ...(document.ownerBackendNodeId !== undefined
-      ? { ownerBackendNodeId: document.ownerBackendNodeId }
-      : {}),
-  }));
+  return documents.map((document) => {
+    let recordingDocumentId: string | undefined;
+    for (const node of document.domNodes) {
+      recordingDocumentId = readRecordingDocumentIdentity(node.attrs);
+      if (recordingDocumentId) break;
+    }
+    return {
+      frameId: document.frameId,
+      target: document.target,
+      ...(document.parentFrameId ? { parentFrameId: document.parentFrameId } : {}),
+      ...(document.ownerBackendNodeId !== undefined
+        ? { ownerBackendNodeId: document.ownerBackendNodeId }
+        : {}),
+      ...(recordingDocumentId ? { recordingDocumentId } : {}),
+    };
+  });
 }
 
 function projectMatchNodes(documents: CapturedFrameDocument<FrameAxNode>[]): CaptureVomMatchNode[] {

apps/extension/src/tools/vom/rendered-surfaces/cluster.ts

@@ -0,0 +1,65 @@
+import type { Rect } from "@browser-skill/vom";
+import type { RenderedSurface, RenderedSurfaceGroup } from "./types";
+
+const STACK_IOU_RATIO = 0.9;
+const STACK_SIZE_RATIO = 0.9;
+
+function area(rect: Rect): number {
+  return Math.max(0, rect.w) * Math.max(0, rect.h);
+}
+
+function intersectionArea(a: Rect, b: Rect): number {
+  const width = Math.max(0, Math.min(a.x + a.w, b.x + b.w) - Math.max(a.x, b.x));
+  const height = Math.max(0, Math.min(a.y + a.h, b.y + b.h) - Math.max(a.y, b.y));
+  return width * height;
+}
+
+function sameVisualStack(a: RenderedSurface, b: RenderedSurface): boolean {
+  if (a.frameId !== b.frameId) return false;
+  if (a.parentBackendNodeId !== b.parentBackendNodeId) return false;
+  const aArea = area(a.visibleRect);
+  const bArea = area(b.visibleRect);
+  const intersection = intersectionArea(a.visibleRect, b.visibleRect);
+  const union = aArea + bArea - intersection;
+  const widthRatio =
+    Math.min(a.visibleRect.w, b.visibleRect.w) / Math.max(a.visibleRect.w, b.visibleRect.w);
+  const heightRatio =
+    Math.min(a.visibleRect.h, b.visibleRect.h) / Math.max(a.visibleRect.h, b.visibleRect.h);
+  return (
+    union > 0 &&
+    intersection / union >= STACK_IOU_RATIO &&
+    widthRatio >= STACK_SIZE_RATIO &&
+    heightRatio >= STACK_SIZE_RATIO
+  );
+}
+
+function toGroup(members: RenderedSurface[]): RenderedSurfaceGroup {
+  const representative = [...members].sort(
+    (a, b) => area(b.visibleRect) - area(a.visibleRect) || b.paintOrder - a.paintOrder,
+  )[0];
+  return {
+    frameId: representative.frameId,
+    members,
+    representative,
+    label: members.map((surface) => surface.label).find((label) => label !== undefined),
+  };
+}
+
+export function clusterRenderedSurfaces(surfaces: RenderedSurface[]): RenderedSurfaceGroup[] {
+  const groups: RenderedSurface[][] = [];
+  for (const surface of surfaces) {
+    const matching = groups.find((group) =>
+      group.some((member) => sameVisualStack(member, surface)),
+    );
+    if (matching) matching.push(surface);
+    else groups.push([surface]);
+  }
+  return groups
+    .map(toGroup)
+    .sort(
+      (a, b) =>
+        a.frameId.localeCompare(b.frameId) ||
+        a.representative.visibleRect.y - b.representative.visibleRect.y ||
+        a.representative.visibleRect.x - b.representative.visibleRect.x,
+    );
+}

apps/extension/src/tools/vom/rendered-surfaces/discovery.ts

@@ -0,0 +1,113 @@
+import type { Rect, Viewport } from "@browser-skill/vom";
+import type { CapturedNode } from "../capture";
+import type { CapturedFrameDocument } from "../frame-capture";
+import type { SemanticAxNode } from "../semantic-graph";
+import type { RenderedSurface } from "./types";
+
+function clean(value: string | undefined): string | undefined {
+  const normalized = value?.replace(/\s+/g, " ").trim();
+  return normalized || undefined;
+}
+
+function intersectViewport(rect: Rect, viewport: Viewport): Rect | null {
+  return intersectRect(rect, { x: 0, y: 0, w: viewport.width, h: viewport.height });
+}
+
+function intersectRect(a: Rect, b: Rect): Rect | null {
+  const x = Math.max(a.x, b.x);
+  const y = Math.max(a.y, b.y);
+  const right = Math.min(a.x + a.w, b.x + b.w);
+  const bottom = Math.min(a.y + a.h, b.y + b.h);
+  if (right <= x || bottom <= y) return null;
+  return { x, y, w: right - x, h: bottom - y };
+}
+
+const CLIPPING_OVERFLOW = new Set(["auto", "clip", "hidden", "scroll"]);
+
+function clipToOverflowAncestors(
+  node: CapturedNode,
+  rect: Rect,
+  nodesByBackend: ReadonlyMap<number, CapturedNode>,
+): Rect | null {
+  let clipped: Rect | null = rect;
+  let parentBackendNodeId = node.parentBackendNodeId;
+  let guard = 0;
+  while (clipped && parentBackendNodeId !== null && guard <= nodesByBackend.size) {
+    const parent = nodesByBackend.get(parentBackendNodeId);
+    if (!parent) break;
+    if (parent.rect) {
+      const clipX = CLIPPING_OVERFLOW.has(parent.overflowX ?? "visible");
+      const clipY = CLIPPING_OVERFLOW.has(parent.overflowY ?? "visible");
+      if (clipX || clipY) {
+        const clipRect = {
+          x: clipX ? parent.rect.x : clipped.x,
+          y: clipY ? parent.rect.y : clipped.y,
+          w: clipX ? parent.rect.w : clipped.w,
+          h: clipY ? parent.rect.h : clipped.h,
+        };
+        clipped = intersectRect(clipped, clipRect);
+      }
+    }
+    parentBackendNodeId = parent.parentBackendNodeId;
+    guard += 1;
+  }
+  return clipped;
+}
+
+function excludedByDomPolicy(
+  node: CapturedNode,
+  nodesByBackend: Map<number, CapturedNode>,
+  excludedBackendNodeIds: ReadonlySet<number>,
+): boolean {
+  let current: CapturedNode | undefined = node;
+  let guard = 0;
+  while (current && guard <= nodesByBackend.size) {
+    if (excludedBackendNodeIds.has(current.backendNodeId)) return true;
+    if (current.visuallySuppressed === true) return true;
+    const attrs = current.attrs;
+    if (
+      Object.prototype.hasOwnProperty.call(attrs, "hidden") ||
+      Object.prototype.hasOwnProperty.call(attrs, "inert") ||
+      (attrs["aria-hidden"] ?? "").toLowerCase() === "true"
+    ) {
+      return true;
+    }
+    current =
+      current.parentBackendNodeId === null
+        ? undefined
+        : nodesByBackend.get(current.parentBackendNodeId);
+    guard += 1;
+  }
+  return false;
+}
+
+export function discoverRenderedSurfaces(
+  documents: CapturedFrameDocument<SemanticAxNode>[],
+  viewport: Viewport,
+  excludedBackendNodeIds: ReadonlySet<number> = new Set(),
+): RenderedSurface[] {
+  const surfaces: RenderedSurface[] = [];
+  for (const document of documents) {
+    const nodesByBackend = new Map(document.domNodes.map((node) => [node.backendNodeId, node]));
+    for (const node of document.domNodes) {
+      if (node.tag.toLowerCase() !== "canvas" || node.rendered !== true || !node.rect) continue;
+      if (excludedByDomPolicy(node, nodesByBackend, excludedBackendNodeIds)) continue;
+      const viewportRect = intersectViewport(node.rect, viewport);
+      const visibleRect = viewportRect
+        ? clipToOverflowAncestors(node, viewportRect, nodesByBackend)
+        : null;
+      if (!visibleRect) continue;
+      const label = clean(node.attrs["aria-label"] ?? node.attrs.title);
+      surfaces.push({
+        renderingKind: "canvas",
+        frameId: document.frameId,
+        backendNodeId: node.backendNodeId,
+        parentBackendNodeId: node.parentBackendNodeId,
+        visibleRect,
+        paintOrder: node.paintOrder,
+        ...(label ? { label } : {}),
+      });
+    }
+  }
+  return surfaces;
+}

apps/extension/src/tools/vom/rendered-surfaces/index.ts

@@ -0,0 +1,4 @@
+export { clusterRenderedSurfaces } from "./cluster";
+export { discoverRenderedSurfaces } from "./discovery";
+export { projectRenderedSurfaces } from "./project";
+export type { RenderedSurface, RenderedSurfaceGroup } from "./types";

apps/extension/src/tools/vom/rendered-surfaces/project.ts

@@ -0,0 +1,100 @@
+import type { VomScene, VomVisualSurface } from "@browser-skill/vom";
+import type { CapturedFrameDocument } from "../frame-capture";
+import type { SemanticAxNode } from "../semantic-graph";
+import type { RenderedSurfaceGroup } from "./types";
+
+function frameBackendKey(frameId: string, backendNodeId: number): string {
+  return `${frameId}\u0000${backendNodeId}`;
+}
+
+interface ProjectionIndex {
+  sceneByBackend: ReadonlyMap<string, number>;
+  documentByFrame: ReadonlyMap<string, CapturedFrameDocument<SemanticAxNode>>;
+  domByFrame: ReadonlyMap<
+    string,
+    ReadonlyMap<number, CapturedFrameDocument<SemanticAxNode>["domNodes"][number]>
+  >;
+  rootSceneIdByFrame: ReadonlyMap<string, number>;
+}
+
+function nearestSceneParent(index: ProjectionIndex, group: RenderedSurfaceGroup): number | null {
+  const document = index.documentByFrame.get(group.frameId);
+  const domByBackend = index.domByFrame.get(group.frameId) ?? new Map();
+  let parentBackendNodeId = group.representative.parentBackendNodeId;
+  let guard = 0;
+  while (parentBackendNodeId !== null && guard <= domByBackend.size) {
+    const sceneId = index.sceneByBackend.get(frameBackendKey(group.frameId, parentBackendNodeId));
+    if (sceneId !== undefined) return sceneId;
+    parentBackendNodeId = domByBackend.get(parentBackendNodeId)?.parentBackendNodeId ?? null;
+    guard += 1;
+  }
+
+  if (document?.parentFrameId && document.ownerBackendNodeId !== undefined) {
+    const owner = index.sceneByBackend.get(
+      frameBackendKey(document.parentFrameId, document.ownerBackendNodeId),
+    );
+    if (owner !== undefined) return owner;
+  }
+
+  return index.rootSceneIdByFrame.get(group.frameId) ?? null;
+}
+
+function buildProjectionIndex(
+  scene: VomScene,
+  documents: CapturedFrameDocument<SemanticAxNode>[],
+): ProjectionIndex {
+  const rootSceneIdByFrame = new Map<string, number>();
+  for (const node of scene.nodes) {
+    if (
+      node.frameId &&
+      !rootSceneIdByFrame.has(node.frameId) &&
+      ["rootwebarea", "webarea"].includes(node.role?.toLowerCase() ?? "")
+    ) {
+      rootSceneIdByFrame.set(node.frameId, node.id);
+    }
+  }
+  return {
+    sceneByBackend: new Map(
+      scene.nodes.flatMap((node) =>
+        node.backendNodeId === undefined
+          ? []
+          : [[frameBackendKey(node.frameId ?? "", node.backendNodeId), node.id] as const],
+      ),
+    ),
+    documentByFrame: new Map(documents.map((document) => [document.frameId, document])),
+    domByFrame: new Map(
+      documents.map((document) => [
+        document.frameId,
+        new Map(document.domNodes.map((node) => [node.backendNodeId, node])),
+      ]),
+    ),
+    rootSceneIdByFrame,
+  };
+}
+
+export function projectRenderedSurfaces(
+  scene: VomScene,
+  documents: CapturedFrameDocument<SemanticAxNode>[],
+  groups: RenderedSurfaceGroup[],
+): VomScene {
+  const index = buildProjectionIndex(scene, documents);
+  const visualSurfaces: VomVisualSurface[] = [];
+
+  for (const group of groups) {
+    const parentId = nearestSceneParent(index, group);
+    visualSurfaces.push({
+      parentId,
+      backendNodeId: group.representative.backendNodeId,
+      frameId: group.frameId,
+      renderingKind: "canvas",
+      visibleRect: group.representative.visibleRect,
+      ...(group.label ? { label: group.label } : {}),
+      memberCount: group.members.length,
+    });
+  }
+
+  return {
+    ...scene,
+    ...(visualSurfaces.length > 0 ? { visualSurfaces } : {}),
+  };
+}

apps/extension/src/tools/vom/rendered-surfaces/types.ts

@@ -0,0 +1,18 @@
+import type { Rect } from "@browser-skill/vom";
+
+export interface RenderedSurface {
+  renderingKind: "canvas";
+  frameId: string;
+  backendNodeId: number;
+  parentBackendNodeId: number | null;
+  visibleRect: Rect;
+  paintOrder: number;
+  label?: string;
+}
+
+export interface RenderedSurfaceGroup {
+  frameId: string;
+  members: RenderedSurface[];
+  representative: RenderedSurface;
+  label?: string;
+}

apps/extension/src/tools/vom/semantic-graph/build.ts

@@ -0,0 +1,154 @@
+import type { Viewport } from "@browser-skill/vom";
+import type { FrameDocument } from "../frame-document";
+import {
+  frameAxKey,
+  frameBackendKey,
+  type SemanticAxNode,
+  type SemanticFrame,
+  type SemanticGraph,
+  type SemanticGraphNode,
+  type SemanticNodeId,
+} from "./types";
+
+export interface BuildSemanticGraphInput {
+  documents: FrameDocument<SemanticAxNode>[];
+  viewport: Viewport;
+  rootFrameId?: string;
+  excludedBackendNodeIds?: ReadonlySet<number>;
+}
+
+function domNodeId(frameId: string, backendNodeId: number): SemanticNodeId {
+  return JSON.stringify([frameId, "dom", backendNodeId]);
+}
+
+function axNodeId(frameId: string, nodeId: string): SemanticNodeId {
+  return JSON.stringify([frameId, "ax", nodeId]);
+}
+
+export function buildSemanticGraph(input: BuildSemanticGraphInput): SemanticGraph {
+  const rootFrameId =
+    input.rootFrameId ??
+    input.documents.find((document) => !document.parentFrameId)?.frameId ??
+    input.documents[0]?.frameId ??
+    "root";
+  const frames = new Map<string, SemanticFrame>();
+  const nodes = new Map<SemanticNodeId, SemanticGraphNode>();
+  const nodeIdsByFrame = new Map<string, SemanticNodeId[]>();
+  const nodeByFrameBackend = new Map<string, SemanticNodeId>();
+  const nodeByFrameAx = new Map<string, SemanticNodeId>();
+
+  for (const [frameOrder, document] of input.documents.entries()) {
+    frames.set(document.frameId, {
+      frameId: document.frameId,
+      ...(document.parentFrameId ? { parentFrameId: document.parentFrameId } : {}),
+      ...(document.ownerBackendNodeId !== undefined
+        ? { ownerBackendNodeId: document.ownerBackendNodeId }
+        : {}),
+      contextScopeId: document.contextScopeId,
+      target: document.target,
+      ...(document.url ? { url: document.url } : {}),
+      order: frameOrder,
+    });
+
+    const frameNodeIds: SemanticNodeId[] = [];
+    nodeIdsByFrame.set(document.frameId, frameNodeIds);
+    for (const [index, dom] of document.domNodes.entries()) {
+      const id = domNodeId(document.frameId, dom.backendNodeId);
+      const node: SemanticGraphNode = {
+        id,
+        frameId: document.frameId,
+        backendNodeId: dom.backendNodeId,
+        dom,
+        sourceOrder: index,
+        excluded:
+          document.frameId === rootFrameId &&
+          input.excludedBackendNodeIds?.has(dom.backendNodeId) === true,
+      };
+      nodes.set(id, node);
+      frameNodeIds.push(id);
+      nodeByFrameBackend.set(frameBackendKey(document.frameId, dom.backendNodeId), id);
+    }
+
+    for (const [index, ax] of document.axNodes.entries()) {
+      const joinedId =
+        typeof ax.backendDOMNodeId === "number"
+          ? nodeByFrameBackend.get(frameBackendKey(document.frameId, ax.backendDOMNodeId))
+          : undefined;
+      const id = joinedId ?? axNodeId(document.frameId, ax.nodeId);
+      const existing = nodes.get(id);
+      if (existing) {
+        existing.ax = ax;
+        existing.axNodeId = ax.nodeId;
+      } else {
+        nodes.set(id, {
+          id,
+          frameId: document.frameId,
+          ...(typeof ax.backendDOMNodeId === "number"
+            ? { backendNodeId: ax.backendDOMNodeId }
+            : {}),
+          axNodeId: ax.nodeId,
+          ax,
+          sourceOrder: document.domNodes.length + index,
+          excluded:
+            document.frameId === rootFrameId &&
+            typeof ax.backendDOMNodeId === "number" &&
+            input.excludedBackendNodeIds?.has(ax.backendDOMNodeId) === true,
+        });
+        frameNodeIds.push(id);
+      }
+      nodeByFrameAx.set(frameAxKey(document.frameId, ax.nodeId), id);
+    }
+  }
+
+  for (const document of input.documents) {
+    for (const dom of document.domNodes) {
+      const id = nodeByFrameBackend.get(frameBackendKey(document.frameId, dom.backendNodeId));
+      const node = id ? nodes.get(id) : undefined;
+      if (!node || dom.parentBackendNodeId === null) continue;
+      node.domParentId = nodeByFrameBackend.get(
+        frameBackendKey(document.frameId, dom.parentBackendNodeId),
+      );
+    }
+    for (const ax of document.axNodes) {
+      const id = nodeByFrameAx.get(frameAxKey(document.frameId, ax.nodeId));
+      const node = id ? nodes.get(id) : undefined;
+      if (!node || !ax.parentId) continue;
+      node.axParentId = nodeByFrameAx.get(frameAxKey(document.frameId, ax.parentId));
+    }
+  }
+
+  const axChildren = new Map<SemanticNodeId, SemanticNodeId[]>();
+  const excludedQueue: SemanticNodeId[] = [];
+  for (const node of nodes.values()) {
+    if (node.axParentId) {
+      const children = axChildren.get(node.axParentId) ?? [];
+      children.push(node.id);
+      axChildren.set(node.axParentId, children);
+    }
+    if (node.excluded) excludedQueue.push(node.id);
+  }
+  for (let index = 0; index < excludedQueue.length; index += 1) {
+    for (const childId of axChildren.get(excludedQueue[index]) ?? []) {
+      const child = nodes.get(childId);
+      if (!child || child.excluded) continue;
+      child.excluded = true;
+      excludedQueue.push(childId);
+    }
+  }
+
+  for (const frame of frames.values()) {
+    if (!frame.parentFrameId || frame.ownerBackendNodeId === undefined) continue;
+    frame.ownerNodeId = nodeByFrameBackend.get(
+      frameBackendKey(frame.parentFrameId, frame.ownerBackendNodeId),
+    );
+  }
+
+  return {
+    viewport: input.viewport,
+    rootFrameId,
+    frames,
+    nodes,
+    nodeIdsByFrame,
+    nodeByFrameBackend,
+  };
+}

apps/extension/src/tools/vom/semantic-graph/index.ts

@@ -0,0 +1,59 @@
+import type { Viewport, VomScene } from "@browser-skill/vom";
+import type { FrameDocument } from "../frame-document";
+import { buildSemanticGraph as buildGraph } from "./build";
+import { projectSemanticGraph as projectGraph } from "./project";
+import { resolveSemanticGraph as resolveGraph } from "./resolve";
+import { normalizeSemanticStructure as normalizeStructure } from "./structure";
+import type {
+  ResolvedSemanticGraph,
+  SemanticAxNode,
+  SemanticGraph,
+  StructuredSemanticGraph,
+} from "./types";
+
+export type { SemanticAxNode } from "./types";
+
+export interface SemanticVomInput {
+  documents: FrameDocument<SemanticAxNode>[];
+  viewport: Viewport;
+  rootFrameId?: string;
+  excludedBackendNodeIds?: ReadonlySet<number>;
+}
+
+export function buildSemanticGraph(input: SemanticVomInput): SemanticGraph {
+  return buildGraph(input);
+}
+
+export function resolveSemanticGraph(
+  graph: SemanticGraph,
+  options: {
+    supplementalNames?: ReadonlyMap<string, string>;
+    identifierFallback?: boolean;
+  } = {},
+): ResolvedSemanticGraph {
+  return resolveGraph(graph, options);
+}
+
+export function normalizeSemanticStructure(graph: ResolvedSemanticGraph): StructuredSemanticGraph {
+  return normalizeStructure(graph);
+}
+
+export function projectSemanticGraph(graph: StructuredSemanticGraph): VomScene {
+  return projectGraph(graph);
+}
+
+export function buildSemanticVomScene(
+  input: SemanticVomInput & {
+    supplementalNames?: ReadonlyMap<string, string>;
+    identifierFallback?: boolean;
+  },
+): VomScene {
+  return projectSemanticGraph(
+    normalizeSemanticStructure(
+      resolveSemanticGraph(buildSemanticGraph(input), {
+        supplementalNames: input.supplementalNames,
+        identifierFallback: input.identifierFallback,
+      }),
+    ),
+  );
+}

apps/extension/src/tools/vom/semantic-graph/name-evidence.ts

@@ -0,0 +1,34 @@
+const IDENTIFIER_ATTRS = ["data-testid", "data-test-id", "id"] as const;
+const GENERIC_TOKENS = new Set(["btn", "button", "control", "icon", "item", "test", "tool"]);
+const GENERATED_PREFIXES = new Set(["ember", "headlessui", "mui", "radix", "react", "rc"]);
+
+function identifierTokens(value: string): string[] {
+  return value
+    .replace(/([a-z0-9])([A-Z])/g, "$1 $2")
+    .split(/[^a-zA-Z0-9]+/)
+    .map((token) => token.toLowerCase())
+    .filter(Boolean);
+}
+
+function readableIdentifier(value: string | undefined): string | undefined {
+  const raw = value?.trim();
+  if (!raw || raw.length < 3 || raw.length > 80) return undefined;
+  if (/^[a-f0-9]{8,}$/i.test(raw)) return undefined;
+
+  const tokens = identifierTokens(raw);
+  if (GENERATED_PREFIXES.has(tokens[0])) return undefined;
+  while (tokens.length > 1 && GENERIC_TOKENS.has(tokens[0])) tokens.shift();
+  while (tokens.length > 1 && GENERIC_TOKENS.has(tokens[tokens.length - 1])) tokens.pop();
+  if (tokens.length === 0 || !tokens.some((token) => /[a-z]{3,}/.test(token))) return undefined;
+  return tokens
+    .map((token, index) => (index === 0 ? `${token[0].toUpperCase()}${token.slice(1)}` : token))
+    .join(" ");
+}
+
+export function stableIdentifierName(attrs: Readonly<Record<string, string>>): string | undefined {
+  for (const name of IDENTIFIER_ATTRS) {
+    const label = readableIdentifier(attrs[name]);
+    if (label) return label;
+  }
+  return undefined;
+}

apps/extension/src/tools/vom/semantic-graph/project.ts

@@ -0,0 +1,85 @@
+import type { VomNode, VomScene } from "@browser-skill/vom";
+import type { SemanticNodeId, StructuredSemanticGraph, StructuredSemanticNode } from "./types";
+
+function retained(node: StructuredSemanticNode): boolean {
+  return node.structure.kind === "keep" || node.structure.kind === "inferred-group";
+}
+
+function connectedFrameIds(graph: StructuredSemanticGraph): Set<string> {
+  const connected = new Set<string>([graph.rootFrameId]);
+  const childrenByParent = new Map<string, string[]>();
+  for (const frame of graph.frames.values()) {
+    if (!frame.parentFrameId) continue;
+    const children = childrenByParent.get(frame.parentFrameId) ?? [];
+    children.push(frame.frameId);
+    childrenByParent.set(frame.parentFrameId, children);
+  }
+  const queue = [graph.rootFrameId];
+  for (let index = 0; index < queue.length; index += 1) {
+    for (const frameId of childrenByParent.get(queue[index]) ?? []) {
+      if (connected.has(frameId)) continue;
+      const frame = graph.frames.get(frameId);
+      if (!frame?.ownerNodeId) continue;
+      const owner = graph.nodes.get(frame.ownerNodeId);
+      if (!owner || !retained(owner)) continue;
+      connected.add(frame.frameId);
+      queue.push(frame.frameId);
+    }
+  }
+  return connected;
+}
+
+function domAncestors(
+  graph: StructuredSemanticGraph,
+  node: StructuredSemanticNode,
+  numericId: ReadonlyMap<SemanticNodeId, number>,
+): number[] {
+  const ancestors: number[] = [];
+  const seen = new Set<SemanticNodeId>();
+  let current = node.domParentId;
+  while (current && !seen.has(current)) {
+    seen.add(current);
+    const id = numericId.get(current);
+    if (id !== undefined) ancestors.push(id);
+    current = graph.nodes.get(current)?.domParentId;
+  }
+  return ancestors;
+}
+
+export function projectSemanticGraph(graph: StructuredSemanticGraph): VomScene {
+  const connectedFrames = connectedFrameIds(graph);
+  const orderedNodes = [...graph.frames.values()]
+    .filter((frame) => connectedFrames.has(frame.frameId))
+    .sort((a, b) => a.order - b.order)
+    .flatMap((frame) =>
+      (graph.nodeIdsByFrame.get(frame.frameId) ?? [])
+        .map((id) => graph.nodes.get(id))
+        .filter((node): node is StructuredSemanticNode => node !== undefined && retained(node))
+        .sort((a, b) => a.sourceOrder - b.sourceOrder),
+    );
+
+  const numericId = new Map<SemanticNodeId, number>();
+  orderedNodes.forEach((node, index) => numericId.set(node.id, index + 1));
+  const nodes: VomNode[] = orderedNodes.map((node) => ({
+    ...node.vom,
+    id: numericId.get(node.id) as number,
+    parentId: node.semanticParentId ? (numericId.get(node.semanticParentId) ?? null) : null,
+    ...(node.backendNodeId !== undefined ? { backendNodeId: node.backendNodeId } : {}),
+    frameId: node.frameId,
+    contextScopeId: graph.frames.get(node.frameId)?.contextScopeId ?? node.frameId,
+    referenceable: node.referenceable,
+    ...(node.dom
+      ? {
+          domParentId:
+            node.domParentId === undefined ? null : (numericId.get(node.domParentId) ?? null),
+          domAncestorIds: domAncestors(graph, node, numericId),
+        }
+      : {}),
+  }));
+
+  return {
+    viewport: graph.viewport,
+    nodes,
+    rootFrameId: graph.rootFrameId,
+  };
+}

apps/extension/src/tools/vom/semantic-graph/resolve.ts

@@ -0,0 +1,521 @@
+import type { VomNode } from "@browser-skill/vom";
+import { stableIdentifierName } from "./name-evidence";
+import type {
+  ResolvedSemanticGraph,
+  ResolvedSemanticNode,
+  SemanticAxNode,
+  SemanticGraph,
+  SemanticGraphNode,
+  SemanticNodeId,
+} from "./types";
+import { frameBackendKey } from "./types";
+
+const FORM_TAGS = new Set(["input", "textarea", "select"]);
+const NATIVE_CONTROL_TAGS = new Set(["button", "input", "select", "textarea"]);
+const TEXT_AX_ROLES = new Set(["statictext", "inlinetextbox", "labeltext", "text"]);
+const INTERACTIVE_ROLES = new Set([
+  "button",
+  "checkbox",
+  "combobox",
+  "link",
+  "listbox",
+  "menuitem",
+  "menuitemcheckbox",
+  "menuitemradio",
+  "option",
+  "radio",
+  "searchbox",
+  "slider",
+  "spinbutton",
+  "switch",
+  "tab",
+  "textbox",
+  "treeitem",
+]);
+const SENSITIVE_INPUT_TYPES = new Set([
+  "password",
+  "credit-card",
+  "one-time-code",
+  "current-password",
+  "new-password",
+]);
+
+function clean(value: string | undefined): string | undefined {
+  const normalized = value?.replace(/\s+/g, " ").trim();
+  return normalized || undefined;
+}
+
+function axValue(field?: { value?: string | number | boolean }): string | undefined {
+  return field?.value === undefined ? undefined : clean(String(field.value));
+}
+
+function axProperty(node: SemanticAxNode | undefined, name: string): string | undefined {
+  return axValue(node?.properties?.find((property) => property.name === name)?.value);
+}
+
+function normalizeRole(value: string | undefined): string | undefined {
+  const role = clean(value)?.toLowerCase();
+  return role || undefined;
+}
+
+function nativeRole(tag: string, attrs: Record<string, string>): string | undefined {
+  if (tag === "button") return "button";
+  if (tag === "textarea") return "textbox";
+  if (tag === "select") return attrs.multiple === undefined ? "combobox" : "listbox";
+  if (tag === "a" && attrs.href) return "link";
+  if (tag === "iframe") return "Iframe";
+  if (tag === "dialog") return "dialog";
+  if (tag === "img") return "img";
+  if (tag === "table") return "table";
+  if (tag === "tr") return "row";
+  if (tag === "th") return "columnheader";
+  if (tag === "td") return "cell";
+  if (tag === "ul" || tag === "ol") return "list";
+  if (tag === "li") return "listitem";
+  if (/^h[1-6]$/.test(tag)) return "heading";
+  if (tag === "nav") return "navigation";
+  if (tag === "main") return "main";
+  if (tag === "form") return "form";
+  if (tag === "input") {
+    const type = (attrs.type ?? "text").toLowerCase();
+    if (type === "hidden") return undefined;
+    if (type === "checkbox") return "checkbox";
+    if (type === "radio") return "radio";
+    if (type === "range") return "slider";
+    if (type === "number") return "spinbutton";
+    if (type === "search") return "searchbox";
+    if (["button", "submit", "reset", "image"].includes(type)) return "button";
+    return "textbox";
+  }
+  return undefined;
+}
+
+function domRole(tag: string, attrs: Record<string, string>): string | undefined {
+  return normalizeRole(attrs.role) ?? nativeRole(tag, attrs);
+}
+
+function resolvedRole(node: SemanticGraphNode): {
+  value?: string;
+  source: ResolvedSemanticNode["roleSource"];
+} {
+  const rawAxRole = clean(axValue(node.ax?.role));
+  const axRole = normalizeRole(rawAxRole);
+  const attrs = node.dom?.attrs ?? {};
+  const explicitDomRole = normalizeRole(attrs.role);
+  const nativeDomRole = nativeRole(node.dom?.tag.toLowerCase() ?? "", attrs);
+  const usableAxRole = node.ax?.ignored !== true;
+  if (usableAxRole && axRole && !["generic", "none", "presentation"].includes(axRole)) {
+    return { value: rawAxRole, source: "ax" };
+  }
+  if (explicitDomRole) return { value: explicitDomRole, source: "dom-explicit" };
+  if (nativeDomRole) return { value: nativeDomRole, source: "dom-native" };
+  if (rawAxRole) {
+    return { value: rawAxRole, source: usableAxRole ? "ax" : "ax-ignored" };
+  }
+  return { source: "none" };
+}
+
+function sensitive(node: SemanticGraphNode): boolean {
+  const attrs = node.dom?.attrs ?? {};
+  const type = (attrs.type ?? "").toLowerCase();
+  const autocomplete = (attrs.autocomplete ?? "").toLowerCase();
+  return (
+    type === "password" ||
+    autocomplete.startsWith("cc-") ||
+    SENSITIVE_INPUT_TYPES.has(autocomplete) ||
+    SENSITIVE_INPUT_TYPES.has(axProperty(node.ax, "inputType") ?? "")
+  );
+}
+
+function inputState(
+  node: SemanticGraphNode,
+  role: string | undefined,
+  value: string | undefined,
+  isSensitive: boolean,
+): VomNode["inputState"] {
+  if (node.dom?.formState) return node.dom.formState;
+  const tag = node.dom?.tag.toLowerCase() ?? "";
+  if (!FORM_TAGS.has(tag) && !["textbox", "searchbox"].includes(role ?? "")) return undefined;
+  if (isSensitive) return value ? "filled" : "empty";
+  if (node.dom?.formValue !== undefined) {
+    if (node.dom.formValue === "") return "empty";
+    return node.dom.formValue === (node.dom.formDefaultValue ?? "") ? "default" : "filled";
+  }
+  return value ? "filled" : "empty";
+}
+
+function externalHrefHost(
+  href: string | undefined,
+  pageUrl: string | undefined,
+): string | undefined {
+  if (!href || !pageUrl) return undefined;
+  try {
+    const page = new URL(pageUrl);
+    const target = new URL(href, page);
+    return target.origin === page.origin ? undefined : target.hostname;
+  } catch {
+    return undefined;
+  }
+}
+
+interface ResolveIndexes {
+  domChildren: Map<SemanticNodeId, SemanticNodeId[]>;
+  axChildren: Map<SemanticNodeId, SemanticNodeId[]>;
+  domIdIndex: Map<string, SemanticNodeId>;
+  labelForIndex: Map<string, SemanticNodeId[]>;
+  domText: (nodeId: SemanticNodeId) => string | undefined;
+  axText: (nodeId: SemanticNodeId) => string | undefined;
+  hasNativeDescendant: (nodeId: SemanticNodeId) => boolean;
+}
+
+function buildIndexes(graph: SemanticGraph): ResolveIndexes {
+  const domChildren = new Map<SemanticNodeId, SemanticNodeId[]>();
+  const axChildren = new Map<SemanticNodeId, SemanticNodeId[]>();
+  const domIdIndex = new Map<string, SemanticNodeId>();
+  const labelForIndex = new Map<string, SemanticNodeId[]>();
+  for (const node of graph.nodes.values()) {
+    if (node.domParentId) {
+      const children = domChildren.get(node.domParentId) ?? [];
+      children.push(node.id);
+      domChildren.set(node.domParentId, children);
+    }
+    if (node.axParentId) {
+      const children = axChildren.get(node.axParentId) ?? [];
+      children.push(node.id);
+      axChildren.set(node.axParentId, children);
+    }
+    const id = clean(node.dom?.attrs.id);
+    if (id) domIdIndex.set(`${node.frameId}\u0000${id}`, node.id);
+    const targetId = clean(node.dom?.attrs.for);
+    if (node.dom?.tag.toLowerCase() === "label" && targetId) {
+      const key = `${node.frameId}\u0000${targetId}`;
+      const labels = labelForIndex.get(key) ?? [];
+      labels.push(node.id);
+      labelForIndex.set(key, labels);
+    }
+  }
+
+  for (const [parentId, children] of axChildren) {
+    const order = graph.nodes.get(parentId)?.ax?.childIds ?? [];
+    const orderByAxId = new Map(order.map((nodeId, index) => [nodeId, index]));
+    children.sort((a, b) => {
+      const aIndex = orderByAxId.get(graph.nodes.get(a)?.axNodeId ?? "") ?? -1;
+      const bIndex = orderByAxId.get(graph.nodes.get(b)?.axNodeId ?? "") ?? -1;
+      return (
+        (aIndex < 0 ? Number.MAX_SAFE_INTEGER : aIndex) -
+        (bIndex < 0 ? Number.MAX_SAFE_INTEGER : bIndex)
+      );
+    });
+  }
+
+  const textMemo = new Map<SemanticNodeId, string | undefined>();
+  const resolvingText = new Set<SemanticNodeId>();
+  const domText = (nodeId: SemanticNodeId): string | undefined => {
+    if (textMemo.has(nodeId)) return textMemo.get(nodeId);
+    if (resolvingText.has(nodeId)) return undefined;
+    resolvingText.add(nodeId);
+    const node = graph.nodes.get(nodeId);
+    const parts: string[] = [];
+    const own = clean(node?.dom?.textContent);
+    if (own) parts.push(own);
+    for (const childId of domChildren.get(nodeId) ?? []) {
+      const child = graph.nodes.get(childId);
+      const childRole = child
+        ? domRole(child.dom?.tag.toLowerCase() ?? "", child.dom?.attrs ?? {})
+        : undefined;
+      if (childRole && INTERACTIVE_ROLES.has(childRole.toLowerCase())) continue;
+      const childText = domText(childId);
+      if (childText) parts.push(childText);
+      if (parts.join(" ").length >= 240) break;
+    }
+    resolvingText.delete(nodeId);
+    const result = clean(parts.join(" ").slice(0, 240));
+    textMemo.set(nodeId, result);
+    return result;
+  };
+
+  const axTextMemo = new Map<SemanticNodeId, string | undefined>();
+  const resolvingAxText = new Set<SemanticNodeId>();
+  const axText = (nodeId: SemanticNodeId): string | undefined => {
+    if (axTextMemo.has(nodeId)) return axTextMemo.get(nodeId);
+    if (resolvingAxText.has(nodeId)) return undefined;
+    resolvingAxText.add(nodeId);
+    const complete = (value: string | undefined): string | undefined => {
+      resolvingAxText.delete(nodeId);
+      axTextMemo.set(nodeId, value);
+      return value;
+    };
+    const node = graph.nodes.get(nodeId);
+    const role = normalizeRole(axValue(node?.ax?.role)) ?? "";
+    if (TEXT_AX_ROLES.has(role)) {
+      const own = clean(axValue(node?.ax?.name) ?? axValue(node?.ax?.value));
+      if (own) return complete(own);
+    }
+    const parts: string[] = [];
+    for (const childId of axChildren.get(nodeId) ?? []) {
+      const child = graph.nodes.get(childId);
+      const childRole = normalizeRole(axValue(child?.ax?.role)) ?? "";
+      if (INTERACTIVE_ROLES.has(childRole)) continue;
+      const childText = axText(childId);
+      if (childText) parts.push(childText);
+      if (parts.join(" ").length >= 240) break;
+    }
+    return complete(clean(parts.join(" ").slice(0, 240)));
+  };
+
+  const nativeMemo = new Map<SemanticNodeId, boolean>();
+  const hasNativeDescendant = (nodeId: SemanticNodeId): boolean => {
+    const cached = nativeMemo.get(nodeId);
+    if (cached !== undefined) return cached;
+    nativeMemo.set(nodeId, false);
+    for (const childId of domChildren.get(nodeId) ?? []) {
+      const child = graph.nodes.get(childId);
+      const childRole =
+        (child?.ax?.ignored === true ? undefined : normalizeRole(axValue(child?.ax?.role))) ??
+        (child ? domRole(child.dom?.tag.toLowerCase() ?? "", child.dom?.attrs ?? {}) : undefined);
+      if (
+        (child?.dom && NATIVE_CONTROL_TAGS.has(child.dom.tag.toLowerCase())) ||
+        INTERACTIVE_ROLES.has(childRole ?? "") ||
+        hasNativeDescendant(childId)
+      ) {
+        nativeMemo.set(nodeId, true);
+        return true;
+      }
+    }
+    return false;
+  };
+
+  return {
+    domChildren,
+    axChildren,
+    domIdIndex,
+    labelForIndex,
+    domText,
+    axText,
+    hasNativeDescendant,
+  };
+}
+
+function ariaLabelledText(node: SemanticGraphNode, indexes: ResolveIndexes): string | undefined {
+  const ids = (node.dom?.attrs["aria-labelledby"] ?? "").split(/\s+/).filter(Boolean);
+  const parts = ids.flatMap((id) => {
+    const target = indexes.domIdIndex.get(`${node.frameId}\u0000${id}`);
+    return target ? (indexes.domText(target) ?? []) : [];
+  });
+  return clean(parts.join(" "));
+}
+
+function nativeLabelText(
+  node: SemanticGraphNode,
+  graph: SemanticGraph,
+  indexes: ResolveIndexes,
+): string | undefined {
+  const id = clean(node.dom?.attrs.id);
+  if (id) {
+    const labels = indexes.labelForIndex.get(`${node.frameId}\u0000${id}`) ?? [];
+    const explicit = clean(
+      labels
+        .map((labelId) => indexes.domText(labelId))
+        .filter(Boolean)
+        .join(" "),
+    );
+    if (explicit) return explicit;
+  }
+  let parentId = node.domParentId;
+  let guard = 0;
+  while (parentId && guard <= graph.nodes.size) {
+    const parent = graph.nodes.get(parentId);
+    if (!parent) break;
+    if (parent.dom?.tag.toLowerCase() === "label") return indexes.domText(parentId);
+    parentId = parent.domParentId;
+    guard += 1;
+  }
+  return undefined;
+}
+
+function precedingAxText(
+  node: SemanticGraphNode,
+  graph: SemanticGraph,
+  indexes: ResolveIndexes,
+): string | undefined {
+  if (!node.axParentId) return undefined;
+  const siblings = indexes.axChildren.get(node.axParentId) ?? [];
+  const index = siblings.indexOf(node.id);
+  for (let offset = 1; offset <= 4 && index - offset >= 0; offset += 1) {
+    const sibling = graph.nodes.get(siblings[index - offset]);
+    const role = normalizeRole(axValue(sibling?.ax?.role)) ?? "";
+    if (INTERACTIVE_ROLES.has(role)) break;
+    if (!TEXT_AX_ROLES.has(role) && role !== "generic") continue;
+    const text = clean(axValue(sibling?.ax?.name) ?? axValue(sibling?.ax?.value))?.replace(
+      /[：:]\s*$/,
+      "",
+    );
+    if (text && text.length <= 80) return text;
+  }
+  return undefined;
+}
+
+function precedingDomText(
+  node: SemanticGraphNode,
+  graph: SemanticGraph,
+  indexes: ResolveIndexes,
+): string | undefined {
+  if (!node.domParentId) return undefined;
+  const siblings = indexes.domChildren.get(node.domParentId) ?? [];
+  const index = siblings.indexOf(node.id);
+  for (let offset = 1; offset <= 4 && index - offset >= 0; offset += 1) {
+    const sibling = graph.nodes.get(siblings[index - offset]);
+    const siblingRole = sibling
+      ? domRole(sibling.dom?.tag.toLowerCase() ?? "", sibling.dom?.attrs ?? {})
+      : undefined;
+    if (siblingRole && INTERACTIVE_ROLES.has(siblingRole.toLowerCase())) break;
+    const text = indexes.domText(siblings[index - offset])?.replace(/[：:]\s*$/, "");
+    if (text && text.length <= 80) return text;
+  }
+  return undefined;
+}
+
+function resolvedName(
+  node: SemanticGraphNode,
+  role: string | undefined,
+  graph: SemanticGraph,
+  indexes: ResolveIndexes,
+  supplementalNames: ReadonlyMap<string, string>,
+  identifierFallback: boolean,
+): string | undefined {
+  const attrs = node.dom?.attrs ?? {};
+  const formControl = FORM_TAGS.has(node.dom?.tag.toLowerCase() ?? "");
+  const descendantText = indexes.domText(node.id);
+  const interactive =
+    INTERACTIVE_ROLES.has(role?.toLowerCase() ?? "") ||
+    NATIVE_CONTROL_TAGS.has(node.dom?.tag.toLowerCase() ?? "");
+  const candidates = [
+    node.ax?.ignored === true ? undefined : axValue(node.ax?.name),
+    ariaLabelledText(node, indexes),
+    clean(attrs["aria-label"]),
+    nativeLabelText(node, graph, indexes),
+    clean(attrs.title),
+    clean(attrs.alt),
+    node.ax?.ignored === true ? undefined : indexes.axText(node.id),
+    descendantText,
+    formControl ? precedingAxText(node, graph, indexes) : undefined,
+    formControl ? precedingDomText(node, graph, indexes) : undefined,
+    formControl ? clean(node.dom?.formPlaceholder ?? attrs.placeholder) : undefined,
+    formControl || !interactive || node.backendNodeId === undefined
+      ? undefined
+      : clean(supplementalNames.get(frameBackendKey(node.frameId, node.backendNodeId))),
+    identifierFallback && interactive ? stableIdentifierName(attrs) : undefined,
+  ];
+  let name = candidates.find((candidate) => candidate !== undefined);
+  const hasPopup = axProperty(node.ax, "hasPopup");
+  if (name && hasPopup && hasPopup !== "false") {
+    name =
+      axProperty(node.ax, "expanded") === "true" ? `${name} [expanded]` : `${name} [has-submenu]`;
+  }
+  if (!name && role?.toLowerCase() === "iframe") return clean(attrs.id);
+  return name;
+}
+
+function insideNative(node: SemanticGraphNode, graph: SemanticGraph): boolean {
+  let parentId = node.domParentId;
+  let guard = 0;
+  while (parentId && guard <= graph.nodes.size) {
+    const parent = graph.nodes.get(parentId);
+    if (!parent) break;
+    if (parent.dom && NATIVE_CONTROL_TAGS.has(parent.dom.tag.toLowerCase())) return true;
+    parentId = parent.domParentId;
+    guard += 1;
+  }
+  return false;
+}
+
+function nearbyText(
+  node: SemanticGraphNode,
+  graph: SemanticGraph,
+  indexes: ResolveIndexes,
+): string | undefined {
+  if (!node.domParentId) return undefined;
+  const siblings = indexes.domChildren.get(node.domParentId) ?? [];
+  const index = siblings.indexOf(node.id);
+  if (index < 0) return undefined;
+  const texts = siblings
+    .slice(Math.max(0, index - 3), index + 4)
+    .filter((id) => id !== node.id)
+    .flatMap((id) => indexes.domText(id) ?? [])
+    .slice(0, 3);
+  return clean(texts.join(" "));
+}
+
+export function resolveSemanticGraph(
+  graph: SemanticGraph,
+  options: {
+    supplementalNames?: ReadonlyMap<string, string>;
+    identifierFallback?: boolean;
+  } = {},
+): ResolvedSemanticGraph {
+  const indexes = buildIndexes(graph);
+  const supplementalNames = options.supplementalNames ?? new Map<string, string>();
+  const identifierFallback = options.identifierFallback ?? true;
+  const nodes = new Map<SemanticNodeId, ResolvedSemanticNode>();
+  for (const node of graph.nodes.values()) {
+    const roleResolution = resolvedRole(node);
+    const role = roleResolution.value;
+    const name = resolvedName(node, role, graph, indexes, supplementalNames, identifierFallback);
+    const isSensitive = sensitive(node);
+    const sourceValue = node.dom?.formValue ?? axValue(node.ax?.value);
+    const value = isSensitive ? undefined : sourceValue;
+    const attrs = { ...(node.dom?.attrs ?? {}) };
+    if (isSensitive) delete attrs.value;
+    const frame = graph.frames.get(node.frameId);
+    const tag = node.dom?.tag.toLowerCase() ?? "";
+    const vom: ResolvedSemanticNode["vom"] = {
+      tag,
+      rect: node.dom?.rect ?? null,
+      paintOrder: node.dom?.paintOrder ?? 0,
+      position: node.dom?.position || "static",
+      pointerEvents: node.dom?.pointerEvents || "auto",
+      ...(node.dom?.cursor ? { cursor: node.dom.cursor } : {}),
+      ...(role ? { role } : {}),
+      ...(name ? { name } : {}),
+      ...(value !== undefined ? { value } : {}),
+      ...(clean(node.dom?.formPlaceholder ?? attrs.placeholder)
+        ? { placeholder: clean(node.dom?.formPlaceholder ?? attrs.placeholder) }
+        : {}),
+      attrs,
+      ...(clean(node.dom?.textContent) ? { text: clean(node.dom?.textContent) } : {}),
+      ...(nearbyText(node, graph, indexes) ? { nearbyText: nearbyText(node, graph, indexes) } : {}),
+      inputState: inputState(node, role, sourceValue, isSensitive),
+      sensitive: isSensitive,
+      modal:
+        ["dialog", "alertdialog"].includes(role?.toLowerCase() ?? "") ||
+        tag === "dialog" ||
+        (attrs["aria-modal"] ?? "").toLowerCase() === "true",
+      disabled:
+        Object.prototype.hasOwnProperty.call(attrs, "disabled") ||
+        (attrs["aria-disabled"] ?? "").toLowerCase() === "true",
+      inert: Object.prototype.hasOwnProperty.call(attrs, "inert"),
+      hasNativeDescendant: indexes.hasNativeDescendant(node.id),
+      insideNative: insideNative(node, graph),
+      ...(role?.toLowerCase() === "link" ? { href: externalHrefHost(attrs.href, frame?.url) } : {}),
+    };
+    const selected = node.ax?.ignored === true ? undefined : axProperty(node.ax, "selected");
+    const expanded = node.ax?.ignored === true ? undefined : axProperty(node.ax, "expanded");
+    const controls = node.ax?.ignored === true ? undefined : axProperty(node.ax, "controls");
+    if (selected === "true" && !vom.attrs?.["aria-selected"]) {
+      vom.attrs = { ...(vom.attrs ?? {}), "aria-selected": "true" };
+    }
+    if (expanded === "true" && !vom.attrs?.["aria-expanded"]) {
+      vom.attrs = { ...(vom.attrs ?? {}), "aria-expanded": "true" };
+    }
+    if (controls && !vom.attrs?.["aria-controls"]) {
+      vom.attrs = { ...(vom.attrs ?? {}), "aria-controls": controls };
+    }
+    nodes.set(node.id, {
+      ...node,
+      vom,
+      referenceable: node.backendNodeId !== undefined,
+      roleSource: roleResolution.source,
+    });
+  }
+  return { ...graph, nodes };
+}

apps/extension/src/tools/vom/semantic-graph/structure.ts

@@ -0,0 +1,456 @@
+import {
+  applyVomInteractionRecovery,
+  isVomReferenceNode,
+  isVomStructuralRole,
+  type VomNode,
+} from "@browser-skill/vom";
+import type {
+  ResolvedSemanticGraph,
+  ResolvedSemanticNode,
+  SemanticNodeId,
+  StructureDecision,
+  StructuredSemanticGraph,
+  StructuredSemanticNode,
+} from "./types";
+
+const TRANSPARENT_ROLES = new Set(["", "generic", "none", "presentation", "inlinetextbox"]);
+const ROOT_ROLES = new Set(["rootwebarea", "webarea"]);
+const CONTENT_BOUNDARY_ROLES = new Set([
+  "article",
+  "dialog",
+  "document",
+  "feed",
+  "form",
+  "grid",
+  "heading",
+  "iframe",
+  "list",
+  "main",
+  "navigation",
+  "paragraph",
+  "region",
+  "section",
+  "table",
+  "tree",
+]);
+
+function hasMeaningfulRelations(node: ResolvedSemanticNode): boolean {
+  const attrs = node.vom.attrs ?? {};
+  return ["aria-controls", "aria-labelledby", "aria-owns", "aria-describedby"].some((name) =>
+    attrs[name]?.trim(),
+  );
+}
+
+function explicitStructural(node: ResolvedSemanticNode): boolean {
+  return (
+    isVomStructuralRole(node.vom.role) &&
+    node.roleSource !== "none" &&
+    node.roleSource !== "ax-ignored"
+  );
+}
+
+function hasUsableAxSemantics(node: ResolvedSemanticNode): boolean {
+  return node.ax !== undefined && node.ax.ignored !== true;
+}
+
+function isRenderedDomFallback(node: ResolvedSemanticNode): boolean {
+  if (!node.dom) return false;
+  const attrs = node.dom.attrs;
+  if (
+    Object.prototype.hasOwnProperty.call(attrs, "hidden") ||
+    Object.prototype.hasOwnProperty.call(attrs, "inert") ||
+    (attrs["aria-hidden"] ?? "").toLowerCase() === "true"
+  ) {
+    return false;
+  }
+  return node.dom.rendered ?? (node.dom.localRect != null || node.dom.rect != null);
+}
+
+function initialParentId(
+  graph: ResolvedSemanticGraph,
+  node: ResolvedSemanticNode,
+): SemanticNodeId | undefined {
+  let parentId = node.axParentId ?? node.domParentId;
+  if (node.axParentId && node.domParentId && node.axParentId !== node.domParentId) {
+    const axParent = graph.nodes.get(node.axParentId);
+    const axRole = axParent?.vom.role?.toLowerCase() ?? "";
+    const meaningfulAxParent =
+      axParent !== undefined &&
+      !ROOT_ROLES.has(axRole) &&
+      (explicitStructural(axParent) ||
+        !TRANSPARENT_ROLES.has(axRole) ||
+        Boolean(axParent.vom.name || axParent.vom.text || hasMeaningfulRelations(axParent)));
+    parentId = meaningfulAxParent ? node.axParentId : node.domParentId;
+  }
+  if (parentId) return parentId;
+  if (node.frameId === graph.rootFrameId) return undefined;
+  return graph.frames.get(node.frameId)?.ownerNodeId;
+}
+
+function orderedNodes(graph: ResolvedSemanticGraph): ResolvedSemanticNode[] {
+  return [...graph.frames.values()]
+    .sort((a, b) => a.order - b.order)
+    .flatMap((frame) =>
+      (graph.nodeIdsByFrame.get(frame.frameId) ?? [])
+        .map((id) => graph.nodes.get(id))
+        .filter((node): node is ResolvedSemanticNode => node !== undefined)
+        .sort((a, b) => a.sourceOrder - b.sourceOrder),
+    );
+}
+
+function recoveredNodes(
+  graph: ResolvedSemanticGraph,
+  nodes: ResolvedSemanticNode[],
+): Map<SemanticNodeId, VomNode> {
+  const numericId = new Map(nodes.map((node, index) => [node.id, index + 1]));
+  const semanticId = new Map([...numericId].map(([id, numeric]) => [numeric, id]));
+  const provisional = nodes.map((node) => ({
+    ...node.vom,
+    id: numericId.get(node.id) as number,
+    parentId: (() => {
+      const parent = initialParentId(graph, node);
+      return parent ? (numericId.get(parent) ?? null) : null;
+    })(),
+    ...(node.backendNodeId !== undefined ? { backendNodeId: node.backendNodeId } : {}),
+    frameId: node.frameId,
+    contextScopeId: graph.frames.get(node.frameId)?.contextScopeId ?? node.frameId,
+    referenceable: node.referenceable,
+  }));
+  return new Map(
+    applyVomInteractionRecovery(provisional).flatMap((node) => {
+      const id = semanticId.get(node.id);
+      return id ? [[id, node] as const] : [];
+    }),
+  );
+}
+
+function redundantSourceNodes(
+  graph: ResolvedSemanticGraph,
+  nodes: ResolvedSemanticNode[],
+  recovered: ReadonlyMap<SemanticNodeId, VomNode>,
+): Set<SemanticNodeId> {
+  const byKey = new Map<string, ResolvedSemanticNode[]>();
+  for (const node of nodes) {
+    const output = recovered.get(node.id) as VomNode;
+    const name = output.name?.trim().toLowerCase() ?? "";
+    if (!name || !isVomReferenceNode({ ...output, referenceable: true })) continue;
+    const key = `${node.frameId}\u0000${initialParentId(graph, node) ?? ""}\u0000${output.role?.toLowerCase() ?? ""}\u0000${name}\u0000${output.sensitive === true}`;
+    const matches = byKey.get(key) ?? [];
+    matches.push(node);
+    byKey.set(key, matches);
+  }
+  const redundant = new Set<SemanticNodeId>();
+  for (const matches of byKey.values()) {
+    const axOnly = matches.filter((node) => node.ax && !node.dom);
+    const domOnly = matches.filter((node) => node.dom && !node.ax);
+    if (matches.length === 2 && axOnly.length === 1 && domOnly.length === 1) {
+      redundant.add(domOnly[0].id);
+    }
+  }
+  return redundant;
+}
+
+function baseDecision(
+  graph: ResolvedSemanticGraph,
+  node: ResolvedSemanticNode,
+  output: VomNode,
+  frameOwnerIds: ReadonlySet<SemanticNodeId>,
+  redundant: ReadonlySet<SemanticNodeId>,
+): StructureDecision {
+  if (node.excluded) return { kind: "excluded", reason: "excluded" };
+  if (redundant.has(node.id)) return { kind: "excluded", reason: "redundant-source" };
+  if (!hasUsableAxSemantics(node) && !isRenderedDomFallback(node)) {
+    return { kind: "excluded", reason: "non-rendered-dom-fallback" };
+  }
+  if (frameOwnerIds.has(node.id)) return { kind: "keep", reason: "frame-owner" };
+  if (node.frameId !== graph.rootFrameId && ROOT_ROLES.has(output.role?.toLowerCase() ?? "")) {
+    return { kind: "transparent", reason: "child-document-root" };
+  }
+  if (node.ax?.ignored === true && !node.dom) {
+    return { kind: "transparent", reason: "ax-ignored" };
+  }
+  const role = output.role?.toLowerCase() ?? "";
+  if (!TRANSPARENT_ROLES.has(role)) return { kind: "keep", reason: "semantic" };
+  if (
+    output.name ||
+    output.text ||
+    output.value ||
+    output.placeholder ||
+    hasMeaningfulRelations(node) ||
+    (output.rect && ["fixed", "sticky"].includes(output.position))
+  ) {
+    return { kind: "keep", reason: "semantic" };
+  }
+  return { kind: "transparent", reason: "wrapper" };
+}
+
+function buildChildren(
+  nodes: ResolvedSemanticNode[],
+  relation: "axParentId" | "domParentId",
+): Map<SemanticNodeId, SemanticNodeId[]> {
+  const children = new Map<SemanticNodeId, SemanticNodeId[]>();
+  for (const node of nodes) {
+    const parentId = node[relation];
+    if (!parentId) continue;
+    const siblings = children.get(parentId) ?? [];
+    siblings.push(node.id);
+    children.set(parentId, siblings);
+  }
+  return children;
+}
+
+function explicitDomAncestors(
+  graph: ResolvedSemanticGraph,
+  nodes: ResolvedSemanticNode[],
+  domChildren: ReadonlyMap<SemanticNodeId, SemanticNodeId[]>,
+): Set<SemanticNodeId> {
+  const inside = new Set<SemanticNodeId>();
+  const roots = nodes.filter((node) => !node.domParentId);
+  const queue = roots.map((node) => node.id);
+  for (let index = 0; index < queue.length; index += 1) {
+    const parentId = queue[index];
+    const parent = graph.nodes.get(parentId);
+    const parentIsBoundary =
+      parent !== undefined &&
+      explicitStructural(parent) &&
+      !ROOT_ROLES.has(parent.vom.role?.toLowerCase() ?? "");
+    for (const childId of domChildren.get(parentId) ?? []) {
+      if (inside.has(parentId) || parentIsBoundary) inside.add(childId);
+      queue.push(childId);
+    }
+  }
+  return inside;
+}
+
+function reliableGroupCandidates(
+  graph: ResolvedSemanticGraph,
+  nodes: ResolvedSemanticNode[],
+  recovered: ReadonlyMap<SemanticNodeId, VomNode>,
+  decisions: ReadonlyMap<SemanticNodeId, StructureDecision>,
+  domChildren: ReadonlyMap<SemanticNodeId, SemanticNodeId[]>,
+): Set<SemanticNodeId> {
+  const insideExplicitStructure = explicitDomAncestors(graph, nodes, domChildren);
+  const remainingChildren = new Map(
+    nodes.map((node) => [node.id, domChildren.get(node.id)?.length ?? 0]),
+  );
+  const summaries = new Map<SemanticNodeId, { blocked: boolean; interactions: number }>();
+  const queue = nodes
+    .filter((node) => (remainingChildren.get(node.id) ?? 0) === 0)
+    .map((node) => node.id);
+  for (let index = 0; index < queue.length; index += 1) {
+    const nodeId = queue[index];
+    const node = graph.nodes.get(nodeId);
+    const output = recovered.get(nodeId);
+    if (!node || !output) continue;
+    const role = output.role?.toLowerCase() ?? "";
+    const excluded = decisions.get(nodeId)?.kind === "excluded";
+    const blocked = excluded || explicitStructural(node) || CONTENT_BOUNDARY_ROLES.has(role);
+    const summary = excluded
+      ? { blocked: true, interactions: 0 }
+      : isVomReferenceNode(output)
+        ? { blocked: false, interactions: 1 }
+        : blocked
+          ? { blocked: true, interactions: 0 }
+          : (domChildren.get(nodeId) ?? []).reduce(
+              (combined, childId) => {
+                const child = summaries.get(childId);
+                return {
+                  blocked: combined.blocked || !child || child.blocked,
+                  interactions: Math.min(2, combined.interactions + (child?.interactions ?? 0)),
+                };
+              },
+              { blocked: false, interactions: 0 },
+            );
+    summaries.set(nodeId, summary);
+    const parentId = node.domParentId;
+    if (!parentId) continue;
+    const remaining = (remainingChildren.get(parentId) ?? 1) - 1;
+    remainingChildren.set(parentId, remaining);
+    if (remaining === 0) queue.push(parentId);
+  }
+
+  const candidates = new Set<SemanticNodeId>();
+  for (const node of nodes) {
+    const output = recovered.get(node.id) as VomNode;
+    const role = output.role?.toLowerCase() ?? "";
+    if (
+      !node.dom ||
+      node.dom.tag.toLowerCase() !== "div" ||
+      !TRANSPARENT_ROLES.has(role) ||
+      insideExplicitStructure.has(node.id) ||
+      decisions.get(node.id)?.kind === "excluded" ||
+      node.dom.attrs.hidden !== undefined ||
+      (node.dom.attrs["aria-hidden"] ?? "").toLowerCase() === "true" ||
+      node.dom.attrs.inert !== undefined
+    ) {
+      continue;
+    }
+
+    const branches = (domChildren.get(node.id) ?? []).map((id) => summaries.get(id));
+    const blocked = branches.some((summary) => !summary || summary.blocked);
+    const contributingBranches = branches.filter(
+      (summary) => (summary?.interactions ?? 0) > 0,
+    ).length;
+    const interactions = branches.reduce(
+      (count, summary) => Math.min(2, count + (summary?.interactions ?? 0)),
+      0,
+    );
+    if (!blocked && contributingBranches >= 2 && interactions >= 2) {
+      candidates.add(node.id);
+    }
+  }
+  return candidates;
+}
+
+function leafCandidates(
+  nodes: ResolvedSemanticNode[],
+  candidates: ReadonlySet<SemanticNodeId>,
+  domChildren: ReadonlyMap<SemanticNodeId, SemanticNodeId[]>,
+): Set<SemanticNodeId> {
+  const parentById = new Map(
+    nodes.flatMap((node) => (node.domParentId ? ([[node.id, node.domParentId]] as const) : [])),
+  );
+  const childCount = new Map(nodes.map((node) => [node.id, domChildren.get(node.id)?.length ?? 0]));
+  const containsCandidate = new Set<SemanticNodeId>();
+  const queue = nodes.filter((node) => (childCount.get(node.id) ?? 0) === 0).map((node) => node.id);
+  const selected = new Set<SemanticNodeId>();
+  for (let index = 0; index < queue.length; index += 1) {
+    const nodeId = queue[index];
+    if (candidates.has(nodeId) && !containsCandidate.has(nodeId)) selected.add(nodeId);
+    const parentId = parentById.get(nodeId);
+    if (!parentId) continue;
+    if (candidates.has(nodeId) || containsCandidate.has(nodeId)) containsCandidate.add(parentId);
+    const remaining = (childCount.get(parentId) ?? 1) - 1;
+    childCount.set(parentId, remaining);
+    if (remaining === 0) queue.push(parentId);
+  }
+  return selected;
+}
+
+function nearestKept(
+  graph: ResolvedSemanticGraph,
+  startId: SemanticNodeId | undefined,
+  relation: "axParentId" | "domParentId",
+  kept: ReadonlySet<SemanticNodeId>,
+  memo: Map<SemanticNodeId, SemanticNodeId | undefined>,
+): SemanticNodeId | undefined {
+  let currentId = startId;
+  const path: SemanticNodeId[] = [];
+  const seen = new Set<SemanticNodeId>();
+  let result: SemanticNodeId | undefined;
+  while (currentId && !seen.has(currentId)) {
+    if (kept.has(currentId)) {
+      result = currentId;
+      break;
+    }
+    if (memo.has(currentId)) {
+      result = memo.get(currentId);
+      break;
+    }
+    seen.add(currentId);
+    path.push(currentId);
+    currentId = graph.nodes.get(currentId)?.[relation];
+  }
+  for (const id of path) memo.set(id, result);
+  return result;
+}
+
+function finalParentId(
+  graph: ResolvedSemanticGraph,
+  node: ResolvedSemanticNode,
+  kept: ReadonlySet<SemanticNodeId>,
+  decisions: ReadonlyMap<SemanticNodeId, StructureDecision>,
+  axParentMemo: Map<SemanticNodeId, SemanticNodeId | undefined>,
+  domParentMemo: Map<SemanticNodeId, SemanticNodeId | undefined>,
+): SemanticNodeId | undefined {
+  const axParent = nearestKept(graph, node.axParentId, "axParentId", kept, axParentMemo);
+  const domParent = nearestKept(graph, node.domParentId, "domParentId", kept, domParentMemo);
+  const axNode = axParent ? graph.nodes.get(axParent) : undefined;
+  const domNode = domParent ? graph.nodes.get(domParent) : undefined;
+  const axIsRoot = ROOT_ROLES.has(axNode?.vom.role?.toLowerCase() ?? "");
+  const axIsExplicit = axNode ? explicitStructural(axNode) && !axIsRoot : false;
+  const domIsStructural =
+    domNode !== undefined &&
+    (explicitStructural(domNode) || decisions.get(domNode.id)?.kind === "inferred-group");
+  if (axIsExplicit) return axParent;
+  if (domIsStructural) return domParent;
+  if (axParent && !axIsRoot) return axParent;
+  if (domParent) return domParent;
+  if (axParent) return axParent;
+  if (node.frameId === graph.rootFrameId) return undefined;
+  return graph.frames.get(node.frameId)?.ownerNodeId;
+}
+
+function recoveredVom(node: VomNode, inferredGroup: boolean): ResolvedSemanticNode["vom"] {
+  const {
+    id: _id,
+    parentId: _parentId,
+    backendNodeId: _backendNodeId,
+    frameId: _frameId,
+    contextScopeId: _contextScopeId,
+    referenceable: _referenceable,
+    ...vom
+  } = node;
+  if (!inferredGroup) return vom;
+  const { name: _name, text: _text, nearbyText: _nearbyText, ...groupVom } = vom;
+  return { ...groupVom, role: "group" };
+}
+
+export function normalizeSemanticStructure(graph: ResolvedSemanticGraph): StructuredSemanticGraph {
+  const nodes = orderedNodes(graph);
+  const recovered = recoveredNodes(graph, nodes);
+  const redundant = redundantSourceNodes(graph, nodes, recovered);
+  const frameOwnerIds = new Set(
+    [...graph.frames.values()].flatMap((frame) => frame.ownerNodeId ?? []),
+  );
+  const decisions = new Map<SemanticNodeId, StructureDecision>();
+  for (const node of nodes) {
+    decisions.set(
+      node.id,
+      baseDecision(graph, node, recovered.get(node.id) as VomNode, frameOwnerIds, redundant),
+    );
+  }
+
+  const domChildren = buildChildren(nodes, "domParentId");
+  const candidates = reliableGroupCandidates(graph, nodes, recovered, decisions, domChildren);
+  for (const nodeId of leafCandidates(nodes, candidates, domChildren)) {
+    decisions.set(nodeId, {
+      kind: "inferred-group",
+      reason: "independent-interaction-branches",
+    });
+  }
+
+  const kept = new Set(
+    nodes
+      .filter((node) => {
+        const kind = decisions.get(node.id)?.kind;
+        return kind === "keep" || kind === "inferred-group";
+      })
+      .map((node) => node.id),
+  );
+  const axParentMemo = new Map<SemanticNodeId, SemanticNodeId | undefined>();
+  const domParentMemo = new Map<SemanticNodeId, SemanticNodeId | undefined>();
+  const structuredNodes = new Map<SemanticNodeId, StructuredSemanticNode>();
+  for (const node of nodes) {
+    const structure = decisions.get(node.id) as StructureDecision;
+    const inferredGroup = structure.kind === "inferred-group";
+    structuredNodes.set(node.id, {
+      ...node,
+      vom: recoveredVom(recovered.get(node.id) as VomNode, inferredGroup),
+      structure,
+      ...(kept.has(node.id)
+        ? {
+            semanticParentId: finalParentId(
+              graph,
+              node,
+              kept,
+              decisions,
+              axParentMemo,
+              domParentMemo,
+            ),
+          }
+        : {}),
+    });
+  }
+  return { ...graph, nodes: structuredNodes };
+}

apps/extension/src/tools/vom/semantic-graph/types.ts

@@ -0,0 +1,88 @@
+import type { Viewport, VomNode } from "@browser-skill/vom";
+import type { CdpTarget } from "@/browser-driver/frame-graph";
+import type { CapturedNode } from "../capture";
+
+export interface SemanticAxNode {
+  nodeId: string;
+  frameId?: string;
+  parentId?: string;
+  backendDOMNodeId?: number;
+  ignored?: boolean;
+  role?: { type: string; value?: string };
+  name?: { type: string; value?: string };
+  description?: { value?: string };
+  value?: { value?: string | number | boolean };
+  properties?: Array<{ name?: string; value?: { value?: string | number | boolean } }>;
+  childIds?: string[];
+}
+
+export type SemanticNodeId = string;
+
+export interface SemanticFrame {
+  frameId: string;
+  parentFrameId?: string;
+  ownerBackendNodeId?: number;
+  ownerNodeId?: SemanticNodeId;
+  contextScopeId: string;
+  target: CdpTarget;
+  url?: string;
+  order: number;
+}
+
+export interface SemanticGraphNode {
+  id: SemanticNodeId;
+  frameId: string;
+  backendNodeId?: number;
+  axNodeId?: string;
+  ax?: SemanticAxNode;
+  dom?: CapturedNode;
+  axParentId?: SemanticNodeId;
+  domParentId?: SemanticNodeId;
+  sourceOrder: number;
+  excluded: boolean;
+}
+
+export interface SemanticGraph {
+  viewport: Viewport;
+  rootFrameId: string;
+  frames: Map<string, SemanticFrame>;
+  nodes: Map<SemanticNodeId, SemanticGraphNode>;
+  nodeIdsByFrame: Map<string, SemanticNodeId[]>;
+  nodeByFrameBackend: Map<string, SemanticNodeId>;
+}
+
+export interface ResolvedSemanticNode extends SemanticGraphNode {
+  vom: Omit<VomNode, "id" | "parentId" | "backendNodeId" | "frameId" | "contextScopeId">;
+  referenceable: boolean;
+  roleSource: "ax" | "ax-ignored" | "dom-explicit" | "dom-native" | "none";
+}
+
+export interface ResolvedSemanticGraph extends Omit<SemanticGraph, "nodes"> {
+  nodes: Map<SemanticNodeId, ResolvedSemanticNode>;
+}
+
+export type StructureDecision =
+  | { kind: "keep"; reason: "semantic" | "frame-owner" }
+  | { kind: "inferred-group"; reason: "independent-interaction-branches" }
+  | { kind: "transparent"; reason: "wrapper" | "child-document-root" | "ax-ignored" }
+  | {
+      kind: "excluded";
+      reason: "excluded" | "redundant-source" | "non-rendered-dom-fallback";
+    };
+
+export interface StructuredSemanticNode extends ResolvedSemanticNode {
+  structure: StructureDecision;
+  semanticParentId?: SemanticNodeId;
+}
+
+export interface StructuredSemanticGraph extends Omit<ResolvedSemanticGraph, "nodes"> {
+  nodes: Map<SemanticNodeId, StructuredSemanticNode>;
+}
+
+export function frameBackendKey(frameId: string, backendNodeId: number): string {
+  return `${frameId}\u0000${backendNodeId}`;
+}
+
+export function frameAxKey(frameId: string, axNodeId: string): string {
+  return `${frameId}\u0000${axNodeId}`;
+}

apps/extension/src/transport/types.ts

@@ -23,6 +23,7 @@ export type ErrorCode =
 export type RpcErrorReason =
   | "agent_window_scope"
   | "element_not_visible"
+  | "ref_capability_denied"
   | "ref_not_found"
   | "selector_not_found"
   | "target_not_fillable"
@@ -780,6 +781,7 @@ export interface SelectedOptionV3 {
 
 export type StepV3 =
   | ({ op: "navigate" } & StepCommonV3 & { to: string; cause: NavigationCause })
+  | ({ op: "switch_tab" } & StepCommonV3)
   | ({ op: "click" } & StepCommonV3 & { target: TargetDescriptorV3 })
   | ({ op: "hover" } & StepCommonV3 & { target: TargetDescriptorV3 })
   | ({ op: "fill" } & StepCommonV3 & {
@@ -823,6 +825,8 @@ export interface RecordStartParams {
   redact_values?: boolean;
   /** Omitted means v2; `3` requests a state-linked v3 trace. */
   trace_version?: number;
+  /** Client can decode the v3 `switch_tab` step variant. */
+  supports_tab_switch_steps?: boolean;
 }
 
 export interface RecordStartResult {

apps/extension/test-fixtures/rendered-surfaces/README.md

@@ -0,0 +1,105 @@
+# Rendered Surface browser fixtures
+
+These pages exercise Canvas discovery through a real browser DOMSnapshot and AX tree. They are deliberately framework- and site-independent.
+
+## Serve
+
+From the repository root:
+
+```bash
+python3 -m http.server 4173 --bind 127.0.0.1 \
+  --directory apps/extension/test-fixtures/rendered-surfaces
+```
+
+Use an Agent Window large enough to keep the primary matrix visible:
+
+```bash
+bsk session start --width 1440 --height 1100
+bsk navigate http://127.0.0.1:4173/index.html --session <id>
+bsk observe --session <id>
+```
+
+Always stop the session after the run.
+
+## Pages
+
+### `index.html`
+
+Expected individual Surface labels:
+
+- `fixture-basic-large`
+- `fixture-tiny-8px`
+- `fixture-pointer-events-none`
+- `fixture-partial-ax`
+- `fixture-contained-outer`
+- `fixture-contained-inner`
+- `fixture-different-parent-a`
+- `fixture-different-parent-b`
+
+Expected one grouped Surface:
+
+- `fixture-layered-group`, with `layers=2`
+
+Expected absent:
+
+- `fixture-display-none`
+- `fixture-visibility-hidden`
+- `fixture-opacity-zero`
+- `fixture-parent-opacity-zero`
+- `fixture-hidden-attribute`
+- `fixture-inert-parent`
+- `fixture-aria-hidden-parent`
+- `fixture-zero-size`
+- `fixture-offscreen-right`
+- `fixture-fully-overflow-clipped`
+
+`fixture-partially-overflow-clipped` must remain present because part of it is visible. Its screenshot must contain only the browser's final composited view.
+
+### `unlabeled.html`
+
+This page contains eight Canvas elements but must render seven generic Surface markers because
+the two coincident layers form one group.
+
+- Every marker uses the stable fallback label `canvas visual surface`.
+- Exactly one marker has `layers=2`.
+- The two contained canvases remain separate markers.
+- `id`, `class`, `data-testid`, nearby prose, and fallback AX content never become a Surface label.
+- Blank `aria-label` and `title` values behave as no label.
+- Fallback AX content does not suppress the corresponding Surface.
+
+### `frames.html`
+
+Expected Surface labels:
+
+- `fixture-same-origin-frame`
+- `fixture-cross-origin-frame`
+- `fixture-nested-frame`
+
+The cross-origin frame uses `http://localhost:4173` while the parent uses `http://127.0.0.1:4173`. With Chromium site isolation this exercises the OOPIF path without an external service.
+
+### `viewport.html`
+
+Run with a `900x700` Agent Window.
+
+- `fixture-partial-viewport` is partly visible and must be represented.
+- `fixture-below-fold` is absent initially.
+- After scrolling it into view and observing again, `fixture-below-fold` must be represented with a fresh ref.
+
+### `dynamic.html`
+
+Use the normal DOM buttons and re-observe after each action:
+
+- Initial state: `fixture-dynamic` absent.
+- After **Insert canvas**: present.
+- After **Resize to zero**: absent.
+- After **Restore size**: present with a fresh ref.
+- After **Remove canvas**: absent.
+
+## Invariants
+
+- `snapshot` must not emit any of these Surface markers.
+- `observe` must emit only currently visible Canvas surfaces.
+- Existing DOM/AX controls remain readable alongside Surface markers.
+- Missing labels never prevent discovery; naming and discovery are independent.
+- A Surface ref allows `screenshot --ref` and rejects ordinary click/fill/hover/select.
+- No fixture URL, id, label, or layout constant may appear in production discovery code.

apps/extension/test-fixtures/rendered-surfaces/dynamic.html

@@ -0,0 +1,46 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <title>Rendered Surface dynamic matrix</title>
+    <style>
+      html, body { margin: 0; font: 14px system-ui, sans-serif; }
+      body { padding: 16px; }
+      .controls { display: flex; gap: 8px; margin-bottom: 16px; }
+      button { padding: 8px 12px; }
+      canvas { display: block; width: 260px; height: 120px; background: #e8daef; border: 2px solid #7d3c98; }
+    </style>
+  </head>
+  <body>
+    <h1>Dynamic Canvas lifecycle</h1>
+    <div class="controls">
+      <button id="insert" type="button">Insert canvas</button>
+      <button id="zero" type="button">Resize to zero</button>
+      <button id="restore" type="button">Restore size</button>
+      <button id="remove" type="button">Remove canvas</button>
+    </div>
+    <div id="mount"></div>
+    <script>
+      const mount = document.querySelector("#mount");
+      const getCanvas = () => mount.querySelector("canvas");
+      document.querySelector("#insert").addEventListener("click", () => {
+        if (getCanvas()) return;
+        const canvas = document.createElement("canvas");
+        canvas.width = 260;
+        canvas.height = 120;
+        canvas.setAttribute("aria-label", "fixture-dynamic");
+        mount.append(canvas);
+      });
+      document.querySelector("#zero").addEventListener("click", () => {
+        const canvas = getCanvas();
+        if (canvas) canvas.style.cssText = "width:0;height:0;border:0";
+      });
+      document.querySelector("#restore").addEventListener("click", () => {
+        const canvas = getCanvas();
+        if (canvas) canvas.removeAttribute("style");
+      });
+      document.querySelector("#remove").addEventListener("click", () => getCanvas()?.remove());
+    </script>
+  </body>
+</html>

apps/extension/test-fixtures/rendered-surfaces/frame.html

@@ -0,0 +1,28 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <style>
+      html, body { margin: 0; font: 14px system-ui, sans-serif; }
+      body { padding: 12px; background: #fdfefe; }
+      canvas { display: block; width: 220px; height: 90px; background: #d5f5e3; border: 2px solid #1e8449; }
+      iframe { width: 280px; height: 150px; margin-top: 10px; border: 2px solid #85929e; }
+    </style>
+  </head>
+  <body>
+    <canvas id="frame-canvas" width="220" height="90"></canvas>
+    <script>
+      const params = new URLSearchParams(location.search);
+      const canvas = document.querySelector("#frame-canvas");
+      if (params.get("canvas") === "0") canvas.remove();
+      else canvas.setAttribute("aria-label", params.get("label") || "fixture-frame-default");
+      if (params.get("nested") === "1") {
+        const iframe = document.createElement("iframe");
+        iframe.title = "nested fixture frame";
+        iframe.src = "frame.html?label=fixture-nested-frame";
+        document.body.append(iframe);
+      }
+    </script>
+  </body>
+</html>

apps/extension/test-fixtures/rendered-surfaces/frames.html

@@ -0,0 +1,22 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <title>Rendered Surface frame matrix</title>
+    <style>
+      html, body { margin: 0; font: 14px system-ui, sans-serif; }
+      body { padding: 16px; }
+      .frames { display: grid; grid-template-columns: repeat(3, 320px); gap: 16px; }
+      iframe { width: 300px; height: 300px; border: 2px solid #5d6d7e; }
+    </style>
+  </head>
+  <body>
+    <h1>Frame matrix</h1>
+    <div class="frames">
+      <iframe title="same-origin fixture" src="frame.html?label=fixture-same-origin-frame"></iframe>
+      <iframe title="cross-origin fixture" src="http://localhost:4173/frame.html?label=fixture-cross-origin-frame"></iframe>
+      <iframe title="nested fixture" src="frame.html?canvas=0&nested=1"></iframe>
+    </div>
+  </body>
+</html>

apps/extension/test-fixtures/rendered-surfaces/index.html

@@ -0,0 +1,118 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <title>Rendered Surface discovery matrix</title>
+    <style>
+      * { box-sizing: border-box; }
+      html, body { margin: 0; min-height: 100%; font: 14px/1.4 system-ui, sans-serif; }
+      body { padding: 16px; background: #f4f6f8; color: #17202a; }
+      h1 { margin: 0 0 12px; font-size: 20px; }
+      .matrix { display: grid; grid-template-columns: repeat(4, minmax(220px, 1fr)); gap: 12px; }
+      .case { min-height: 150px; padding: 10px; overflow: hidden; border: 1px solid #aeb6bf; border-radius: 6px; background: white; }
+      .case h2 { margin: 0 0 8px; font-size: 13px; }
+      canvas { display: block; background: #d6eaf8; border: 2px solid #2874a6; }
+      .stack { position: relative; width: 180px; height: 90px; }
+      .stack canvas { position: absolute; inset: 0; width: 180px; height: 90px; }
+      .stack canvas + canvas { background: rgb(244 208 63 / 45%); border-color: #b7950b; }
+      .contained { position: relative; width: 190px; height: 100px; }
+      .contained > canvas:first-child { width: 190px; height: 100px; }
+      .contained > canvas:last-child { position: absolute; left: 55px; top: 30px; width: 70px; height: 40px; background: #fadbd8; border-color: #c0392b; }
+      .same-place { position: relative; width: 180px; height: 90px; }
+      .same-place > div { position: absolute; inset: 0; }
+      .same-place canvas { width: 180px; height: 90px; }
+      .same-place > div:last-child canvas { border-color: #7d3c98; background: rgb(210 180 222 / 35%); }
+      .clip-box { width: 100px; height: 70px; overflow: hidden; border: 2px dashed #566573; }
+      .partially-clipped { width: 140px; height: 60px; transform: translateX(45px); }
+      .fully-clipped { width: 80px; height: 50px; transform: translateX(130px); }
+      .tiny { width: 8px; height: 8px; border-width: 1px; }
+    </style>
+  </head>
+  <body>
+    <h1>Rendered Surface discovery matrix</h1>
+    <main class="matrix">
+      <section class="case">
+        <h2>Visible named canvas</h2>
+        <canvas aria-label="fixture-basic-large" width="200" height="90"></canvas>
+      </section>
+
+      <section class="case">
+        <h2>Tiny canvas remains addressable</h2>
+        <canvas class="tiny" aria-label="fixture-tiny-8px" width="8" height="8"></canvas>
+      </section>
+
+      <section class="case">
+        <h2>Visible but pointer-events none</h2>
+        <canvas aria-label="fixture-pointer-events-none" width="180" height="80" style="pointer-events: none"></canvas>
+      </section>
+
+      <section class="case">
+        <h2>Partial AX/fallback content</h2>
+        <canvas aria-label="fixture-partial-ax" width="180" height="80">
+          <button type="button">Fallback button must not suppress the surface</button>
+        </canvas>
+      </section>
+
+      <section class="case">
+        <h2>Two real rendering layers</h2>
+        <div class="stack">
+          <canvas aria-label="fixture-layered-group" width="180" height="90"></canvas>
+          <canvas width="180" height="90"></canvas>
+        </div>
+      </section>
+
+      <section class="case">
+        <h2>Contained canvases are independent</h2>
+        <div class="contained">
+          <canvas aria-label="fixture-contained-outer" width="190" height="100"></canvas>
+          <canvas aria-label="fixture-contained-inner" width="70" height="40"></canvas>
+        </div>
+      </section>
+
+      <section class="case">
+        <h2>Same geometry, different parents</h2>
+        <div class="same-place">
+          <div><canvas aria-label="fixture-different-parent-a" width="180" height="90"></canvas></div>
+          <div><canvas aria-label="fixture-different-parent-b" width="180" height="90"></canvas></div>
+        </div>
+      </section>
+
+      <section class="case">
+        <h2>Partially overflow-clipped</h2>
+        <div class="clip-box">
+          <canvas class="partially-clipped" aria-label="fixture-partially-overflow-clipped" width="140" height="60"></canvas>
+        </div>
+      </section>
+
+      <section class="case">
+        <h2>Fully overflow-clipped</h2>
+        <div class="clip-box">
+          <canvas class="fully-clipped" aria-label="fixture-fully-overflow-clipped" width="80" height="50"></canvas>
+        </div>
+      </section>
+
+      <section class="case">
+        <h2>CSS-hidden variants</h2>
+        <canvas aria-label="fixture-display-none" width="80" height="40" style="display: none"></canvas>
+        <canvas aria-label="fixture-visibility-hidden" width="80" height="40" style="visibility: hidden"></canvas>
+        <canvas aria-label="fixture-opacity-zero" width="80" height="40" style="opacity: 0"></canvas>
+      </section>
+
+      <section class="case">
+        <h2>Hidden ancestor variants</h2>
+        <div style="opacity: 0"><canvas aria-label="fixture-parent-opacity-zero" width="80" height="40"></canvas></div>
+        <div hidden><canvas aria-label="fixture-hidden-attribute" width="80" height="40"></canvas></div>
+        <div inert><canvas aria-label="fixture-inert-parent" width="80" height="40"></canvas></div>
+        <div aria-hidden="true"><canvas aria-label="fixture-aria-hidden-parent" width="80" height="40"></canvas></div>
+      </section>
+
+      <section class="case">
+        <h2>Zero-size and offscreen</h2>
+        <canvas aria-label="fixture-zero-size" width="80" height="40" style="width: 0; height: 0; border: 0"></canvas>
+        <canvas aria-label="fixture-offscreen-right" width="80" height="40" style="position: fixed; left: 5000px; top: 0"></canvas>
+      </section>
+    </main>
+  </body>
+</html>
+

apps/extension/test-fixtures/rendered-surfaces/unlabeled.html

@@ -0,0 +1,68 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <title>Unlabeled Rendered Surface matrix</title>
+    <style>
+      * { box-sizing: border-box; }
+      html, body { margin: 0; min-height: 100%; font: 14px/1.4 system-ui, sans-serif; }
+      body { padding: 16px; background: #f4f6f8; color: #17202a; }
+      h1 { margin: 0 0 12px; font-size: 20px; }
+      .matrix { display: grid; grid-template-columns: repeat(3, minmax(240px, 1fr)); gap: 12px; }
+      .case { min-height: 150px; padding: 10px; overflow: hidden; border: 1px solid #aeb6bf; border-radius: 6px; background: white; }
+      .case h2 { margin: 0 0 8px; font-size: 13px; }
+      .case p { margin: 0 0 8px; }
+      canvas { display: block; background: #d6eaf8; border: 2px solid #2874a6; }
+      .stack { position: relative; width: 180px; height: 90px; }
+      .stack canvas { position: absolute; inset: 0; width: 180px; height: 90px; }
+      .stack canvas + canvas { background: rgb(244 208 63 / 45%); border-color: #b7950b; }
+      .contained { position: relative; width: 190px; height: 100px; }
+      .contained > canvas:first-child { width: 190px; height: 100px; }
+      .contained > canvas:last-child { position: absolute; left: 55px; top: 30px; width: 70px; height: 40px; background: #fadbd8; border-color: #c0392b; }
+    </style>
+  </head>
+  <body>
+    <h1>Unlabeled Rendered Surface matrix</h1>
+    <main class="matrix">
+      <section class="case">
+        <h2>Only engineering attributes</h2>
+        <canvas id="must-not-be-a-label" class="must-not-be-a-label" data-testid="must-not-be-a-label" width="200" height="90"></canvas>
+      </section>
+
+      <section class="case">
+        <h2>Blank explicit names</h2>
+        <canvas aria-label="   " title="   " width="180" height="80"></canvas>
+      </section>
+
+      <section class="case">
+        <h2>Nearby prose is not a Canvas name</h2>
+        <p>must-not-be-inferred-as-a-surface-label</p>
+        <canvas width="180" height="80"></canvas>
+      </section>
+
+      <section class="case">
+        <h2>Fallback AX content does not name or suppress the Canvas</h2>
+        <canvas width="180" height="80">
+          <button type="button">Fallback control remains separate</button>
+        </canvas>
+      </section>
+
+      <section class="case">
+        <h2>Unnamed rendering layers still cluster</h2>
+        <div class="stack">
+          <canvas width="180" height="90"></canvas>
+          <canvas width="180" height="90"></canvas>
+        </div>
+      </section>
+
+      <section class="case">
+        <h2>Unnamed contained canvases stay independent</h2>
+        <div class="contained">
+          <canvas width="190" height="100"></canvas>
+          <canvas width="70" height="40"></canvas>
+        </div>
+      </section>
+    </main>
+  </body>
+</html>

apps/extension/test-fixtures/rendered-surfaces/viewport.html

@@ -0,0 +1,22 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <title>Rendered Surface viewport matrix</title>
+    <style>
+      html, body { margin: 0; font: 14px system-ui, sans-serif; }
+      body { min-height: 1800px; padding: 16px; }
+      canvas { display: block; background: #fdebd0; border: 2px solid #ca6f1e; }
+      #partial { position: fixed; left: -70px; top: 120px; width: 180px; height: 100px; }
+      #below { position: absolute; left: 40px; top: 1350px; width: 240px; height: 120px; }
+    </style>
+  </head>
+  <body>
+    <h1>Viewport matrix</h1>
+    <p>The orange canvas on the left is intentionally clipped by the viewport.</p>
+    <canvas id="partial" aria-label="fixture-partial-viewport" width="180" height="100"></canvas>
+    <canvas id="below" aria-label="fixture-below-fold" width="240" height="120"></canvas>
+  </body>
+</html>
+

crates/bsk-cli/skill/SKILL.md

@@ -80,6 +80,8 @@ Prefer `@eN` refs from the latest snapshot over raw CSS selectors. Use `--ref` /
 
 When VOM renders `[hover first: …]` on an element, the listed items are not currently clickable refs. Run `bsk hover <that-ref> --session <id>`, then immediately run `bsk snapshot` or `bsk observe` again and click the newly visible menu item ref. Do not click the trigger itself unless the user explicitly wants the trigger action.
 
+When `bsk observe` renders `@eN surface ... [visual-only; ...]`, the ref identifies a rendered canvas surface, not an interactable DOM control. Use `bsk screenshot --ref @eN --session <id>` to inspect its visible crop. Do not pass a visual surface ref to click, fill, hover, or select; those commands intentionally reject screenshot-only refs.
+
 ## Observation priority
 
 Start with `bsk observe` to understand page structure, text, controls, element refs, and conditional hover/focus surfaces. Use `bsk snapshot` only when you need the stricter static accessibility tree or VOM is insufficient. Only escalate to raw HTML or screenshots when the latest observation cannot answer the question:

crates/bsk-cli/src/cli/record.rs

@@ -115,6 +115,7 @@ fn dispatch_start(args: RecordStartArgs, format: Format) -> Result<(), CliError>
         max_page_tokens: args.max_page_tokens,
         redact_values: Some(args.redact_values),
         trace_version: Some(TRACE_VERSION_V3),
+        supports_tab_switch_steps: Some(true),
     };
     let start_result = business_rpc::call::<RecordStartParams, RecordStartResult>(
         info.sock_path.clone(),

crates/bsk-cli/src/cli/render_error.rs

@@ -40,6 +40,7 @@ use bsk_protocol::ErrorCode;
 pub mod reason {
     pub const AGENT_WINDOW_SCOPE: &str = "agent_window_scope";
     pub const ELEMENT_NOT_VISIBLE: &str = "element_not_visible";
+    pub const REF_CAPABILITY_DENIED: &str = "ref_capability_denied";
     pub const REF_NOT_FOUND: &str = "ref_not_found";
     pub const SELECTOR_NOT_FOUND: &str = "selector_not_found";
     pub const TARGET_NOT_FILLABLE: &str = "target_not_fillable";
@@ -228,6 +229,13 @@ pub fn info_for_error(code: ErrorCode, data: Option<&serde_json::Value>) -> Rend
             ),
             exit_code: base.exit_code,
         },
+        (ErrorCode::PermissionDenied, reason::REF_CAPABILITY_DENIED) => RenderInfo {
+            summary: "snapshot ref does not support this operation",
+            hint: Some(
+                "visual surface refs are screenshot-only; run `bsk screenshot --ref <ref> --session <id>`",
+            ),
+            exit_code: base.exit_code,
+        },
         (ErrorCode::InvalidParams, reason::TARGET_NOT_SELECT) => RenderInfo {
             summary: "target element is not a <select>",
             hint: Some(
@@ -377,6 +385,18 @@ mod tests {
         assert!(!info.summary.contains("sandbox"));
     }
 
+    #[test]
+    fn ref_capability_denied_explains_visual_surface_refs() {
+        let data = serde_json::json!({ "reason": reason::REF_CAPABILITY_DENIED });
+        let info = info_for_error(ErrorCode::PermissionDenied, Some(&data));
+        assert_eq!(info.summary, "snapshot ref does not support this operation");
+        assert!(
+            info.hint.unwrap().contains("screenshot-only"),
+            "expected visual-surface-specific hint"
+        );
+        assert_eq!(info.exit_code, 1);
+    }
+
     #[test]
     fn session_busy_overrides_timeout_copy() {
         let data = serde_json::json!({ "reason": reason::SESSION_BUSY });

crates/bsk-protocol/schema/tool_record_await_result.json

@@ -480,6 +480,36 @@
             }
           }
         },
+        {
+          "description": "Fields shared by every step variant (flattened in JSON).",
+          "type": "object",
+          "required": [
+            "id",
+            "op",
+            "result",
+            "state"
+          ],
+          "properties": {
+            "id": {
+              "type": "integer",
+              "format": "uint32",
+              "minimum": 0.0
+            },
+            "op": {
+              "type": "string",
+              "enum": [
+                "switch_tab"
+              ]
+            },
+            "result": {
+              "$ref": "#/definitions/StepResultV3"
+            },
+            "state": {
+              "description": "Observation id immediately before this action.",
+              "type": "string"
+            }
+          }
+        },
         {
           "description": "Fields shared by every step variant (flattened in JSON).",
           "type": "object",

crates/bsk-protocol/schema/tool_record_start_params.json

@@ -29,6 +29,13 @@
     "session_id": {
       "type": "string"
     },
+    "supports_tab_switch_steps": {
+      "description": "Client can decode the v3 `switch_tab` step variant.",
+      "type": [
+        "boolean",
+        "null"
+      ]
+    },
     "tab_id": {
       "type": [
         "integer",

crates/bsk-protocol/schema/tool_record_stop_result.json

@@ -480,6 +480,36 @@
             }
           }
         },
+        {
+          "description": "Fields shared by every step variant (flattened in JSON).",
+          "type": "object",
+          "required": [
+            "id",
+            "op",
+            "result",
+            "state"
+          ],
+          "properties": {
+            "id": {
+              "type": "integer",
+              "format": "uint32",
+              "minimum": 0.0
+            },
+            "op": {
+              "type": "string",
+              "enum": [
+                "switch_tab"
+              ]
+            },
+            "result": {
+              "$ref": "#/definitions/StepResultV3"
+            },
+            "state": {
+              "description": "Observation id immediately before this action.",
+              "type": "string"
+            }
+          }
+        },
         {
           "description": "Fields shared by every step variant (flattened in JSON).",
           "type": "object",

crates/bsk-protocol/schema/trace.json

@@ -469,6 +469,36 @@
             }
           }
         },
+        {
+          "description": "Fields shared by every step variant (flattened in JSON).",
+          "type": "object",
+          "required": [
+            "id",
+            "op",
+            "result",
+            "state"
+          ],
+          "properties": {
+            "id": {
+              "type": "integer",
+              "format": "uint32",
+              "minimum": 0.0
+            },
+            "op": {
+              "type": "string",
+              "enum": [
+                "switch_tab"
+              ]
+            },
+            "result": {
+              "$ref": "#/definitions/StepResultV3"
+            },
+            "state": {
+              "description": "Observation id immediately before this action.",
+              "type": "string"
+            }
+          }
+        },
         {
           "description": "Fields shared by every step variant (flattened in JSON).",
           "type": "object",

crates/bsk-protocol/schema/trace_step.json

@@ -431,6 +431,36 @@
             }
           }
         },
+        {
+          "description": "Fields shared by every step variant (flattened in JSON).",
+          "type": "object",
+          "required": [
+            "id",
+            "op",
+            "result",
+            "state"
+          ],
+          "properties": {
+            "id": {
+              "type": "integer",
+              "format": "uint32",
+              "minimum": 0.0
+            },
+            "op": {
+              "type": "string",
+              "enum": [
+                "switch_tab"
+              ]
+            },
+            "result": {
+              "$ref": "#/definitions/StepResultV3"
+            },
+            "state": {
+              "description": "Observation id immediately before this action.",
+              "type": "string"
+            }
+          }
+        },
         {
           "description": "Fields shared by every step variant (flattened in JSON).",
           "type": "object",

crates/bsk-protocol/schema/trace_step_v3.json

@@ -41,6 +41,36 @@
         }
       }
     },
+    {
+      "description": "Fields shared by every step variant (flattened in JSON).",
+      "type": "object",
+      "required": [
+        "id",
+        "op",
+        "result",
+        "state"
+      ],
+      "properties": {
+        "id": {
+          "type": "integer",
+          "format": "uint32",
+          "minimum": 0.0
+        },
+        "op": {
+          "type": "string",
+          "enum": [
+            "switch_tab"
+          ]
+        },
+        "result": {
+          "$ref": "#/definitions/StepResultV3"
+        },
+        "state": {
+          "description": "Observation id immediately before this action.",
+          "type": "string"
+        }
+      }
+    },
     {
       "description": "Fields shared by every step variant (flattened in JSON).",
       "type": "object",

crates/bsk-protocol/schema/trace_v3.json

@@ -173,6 +173,36 @@
             }
           }
         },
+        {
+          "description": "Fields shared by every step variant (flattened in JSON).",
+          "type": "object",
+          "required": [
+            "id",
+            "op",
+            "result",
+            "state"
+          ],
+          "properties": {
+            "id": {
+              "type": "integer",
+              "format": "uint32",
+              "minimum": 0.0
+            },
+            "op": {
+              "type": "string",
+              "enum": [
+                "switch_tab"
+              ]
+            },
+            "result": {
+              "$ref": "#/definitions/StepResultV3"
+            },
+            "state": {
+              "description": "Observation id immediately before this action.",
+              "type": "string"
+            }
+          }
+        },
         {
           "description": "Fields shared by every step variant (flattened in JSON).",
           "type": "object",

crates/bsk-protocol/src/tools/record.rs

@@ -39,6 +39,9 @@ pub struct RecordStartParams {
     /// Desired trace export format. Omitted means v2; `3` requests v3.
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub trace_version: Option<u32>,
+    /// Client can decode the v3 `switch_tab` step variant.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub supports_tab_switch_steps: Option<bool>,
 }
 
 #[derive(Debug, Clone, PartialEq, Serialize, Deserialize, JsonSchema)]
@@ -423,6 +426,19 @@ mod tests {
         assert_eq!(round, step);
     }
 
+    #[test]
+    fn step_switch_tab_round_trips() {
+        let step = StepV3::SwitchTab {
+            common: sample_common(2, "s2", "s5"),
+        };
+        let v = serde_json::to_value(&step).unwrap();
+        assert_eq!(v["op"], "switch_tab");
+        assert_eq!(v["state"], "s2");
+        assert_eq!(v["result"]["state"], "s5");
+        let round: StepV3 = serde_json::from_value(v).unwrap();
+        assert_eq!(round, step);
+    }
+
     #[test]
     fn trace_v3_round_trips() {
         let trace = sample_trace();
@@ -463,10 +479,12 @@ mod tests {
             max_page_tokens: None,
             redact_values: None,
             trace_version: None,
+            supports_tab_switch_steps: None,
         };
         let legacy_value = serde_json::to_value(legacy).unwrap();
         assert!(legacy_value.get("trace_version").is_none());
         assert!(legacy_value.get("max_page_tokens").is_none());
+        assert!(legacy_value.get("supports_tab_switch_steps").is_none());
 
         let v3 = RecordStartParams {
             session_id: "session".into(),
@@ -476,11 +494,13 @@ mod tests {
             max_page_tokens: Some(4_000),
             redact_values: Some(true),
             trace_version: Some(TRACE_VERSION_V3),
+            supports_tab_switch_steps: Some(true),
         };
         let v3_value = serde_json::to_value(v3).unwrap();
         assert_eq!(v3_value["trace_version"], TRACE_VERSION_V3);
         assert_eq!(v3_value["max_page_tokens"], 4_000);
         assert_eq!(v3_value["redact_values"], true);
+        assert_eq!(v3_value["supports_tab_switch_steps"], true);
     }
 
     #[test]

crates/bsk-protocol/src/tools/record_v3.rs

@@ -126,6 +126,10 @@ pub enum StepV3 {
         to: String,
         cause: NavigationCause,
     },
+    SwitchTab {
+        #[serde(flatten)]
+        common: StepCommonV3,
+    },
     Click {
         #[serde(flatten)]
         common: StepCommonV3,
@@ -340,6 +344,19 @@ mod tests {
         assert_eq!(round, step);
     }
 
+    #[test]
+    fn step_switch_tab_round_trips() {
+        let step = StepV3::SwitchTab {
+            common: sample_common(2, "s2", "s5"),
+        };
+        let v = serde_json::to_value(&step).unwrap();
+        assert_eq!(v["op"], "switch_tab");
+        assert_eq!(v["state"], "s2");
+        assert_eq!(v["result"]["state"], "s5");
+        let round: StepV3 = serde_json::from_value(v).unwrap();
+        assert_eq!(round, step);
+    }
+
     #[test]
     fn trace_v3_round_trips() {
         let trace = sample_trace();

packages/dsh-plugin-browserskill/src/tools.ts

@@ -485,7 +485,8 @@ export function registerTools(deps: ToolDeps): () => void {
       ? "Capture an indented aria-tree snapshot of the session's active tab. Interactive elements " +
         "carry @eN refs for browser_click / browser_fill. Prefer browser_observe for a richer semantic view."
       : "Produce a semantic VOM observation of the session's active tab (roles, states, perception " +
-        "probes) with @eN refs for browser_click / browser_fill. Read-only: never submits input.";
+        "probes) with @eN refs. Visual surface refs are screenshot-only; DOM refs support interaction. " +
+        "Read-only: never submits input.";
     register(
       defineTool({
         name,
@@ -748,12 +749,14 @@ export function registerTools(deps: ToolDeps): () => void {
       name: "browser_screenshot",
       description:
         "Capture a PNG screenshot of the session's active tab, or crop to a snapshot ref element. " +
-        "Returns the image itself when the deployment supports image input, otherwise a file path.",
+        "This is the supported operation for visual surface refs emitted by browser_observe. Returns " +
+        "the image itself when the deployment supports image input, otherwise a file path.",
       parameters: {
         session: SESSION_PARAM,
         ref: {
           type: "string",
-          description: "Snapshot ref (@e3) from the last snapshot/observe; crops to that element.",
+          description:
+            "Ref (@e3) from the last snapshot/observe; crops to that DOM element or visual surface.",
         },
       },
       output: {

packages/vom/src/__tests__/render.test.ts

@@ -29,6 +29,66 @@ function coreRefs(refs: ReturnType<typeof renderVom>["refs"]) {
 }
 
 describe("renderVom single-layer page", () => {
+  it("renders visual surfaces as screenshot-only refs", () => {
+    const input = scene([
+      node({ id: 1, role: "RootWebArea", frameId: "main" }),
+      node({ id: 2, parentId: 1, role: "Iframe", frameId: "main", backendNodeId: 20 }),
+    ]);
+    input.visualSurfaces = [
+      {
+        parentId: 2,
+        backendNodeId: 99,
+        frameId: "child",
+        renderingKind: "canvas",
+        visibleRect: { x: 10, y: 20, w: 800, h: 500 },
+        label: "Data grid",
+        memberCount: 2,
+      },
+    ];
+    const out = renderVom(input);
+
+    expect(out.text).toContain(
+      '@e1 surface "Data grid" [rendering=canvas; layers=2; visual-only; use: bsk screenshot --ref @e1]',
+    );
+    expect(out.refs).toContainEqual(
+      expect.objectContaining({
+        ref: "e1",
+        backendNodeId: 99,
+        kind: "surface",
+        visibleRect: { x: 10, y: 20, w: 800, h: 500 },
+        capabilities: ["screenshot"],
+      }),
+    );
+  });
+
+  it("renders an unnamed visual surface with a stable generic label", () => {
+    const input = scene([node({ id: 1, role: "RootWebArea", frameId: "main" })]);
+    input.visualSurfaces = [
+      {
+        parentId: 1,
+        backendNodeId: 99,
+        frameId: "main",
+        renderingKind: "canvas",
+        visibleRect: { x: 10, y: 20, w: 800, h: 500 },
+        memberCount: 1,
+      },
+    ];
+
+    const out = renderVom(input);
+
+    expect(out.text).toContain(
+      '@e1 surface "canvas visual surface" [rendering=canvas; visual-only; use: bsk screenshot --ref @e1]',
+    );
+    expect(out.refs).toContainEqual(
+      expect.objectContaining({
+        ref: "e1",
+        name: "canvas visual surface",
+        kind: "surface",
+        capabilities: ["screenshot"],
+      }),
+    );
+  });
+
   it("does not derive handle context across frame scopes", () => {
     const out = renderVom(
       scene([
@@ -333,6 +393,84 @@ describe("renderVom single-layer page", () => {
     expect(coreRefs(out.refs)).toEqual([{ ref: "e1", backendNodeId: 2 }]);
   });
 
+  it("does not treat implementation CSS classes as control names", () => {
+    const out = renderVom(
+      scene([
+        node({ id: 1, role: "RootWebArea", name: "Doc" }),
+        node({
+          id: 2,
+          parentId: 1,
+          role: "generic",
+          cursor: "pointer",
+          attrs: { onclick: "handleClick()" },
+          rect: { x: 20, y: 20, w: 40, h: 40 },
+        }),
+        node({
+          id: 3,
+          parentId: 2,
+          role: "img",
+          tag: "svg",
+          attrs: { class: "kocomz" },
+        }),
+      ]),
+    );
+
+    expect(out.text).not.toContain("kocomz");
+    expect(out.refs).toEqual([]);
+  });
+
+  it("recovers icon controls only from explicit semantic icon evidence", () => {
+    const out = renderVom(
+      scene([
+        node({ id: 1, role: "RootWebArea", name: "Doc" }),
+        node({
+          id: 2,
+          parentId: 1,
+          role: "generic",
+          cursor: "pointer",
+          attrs: { onclick: "handleFilter()" },
+          rect: { x: 20, y: 20, w: 40, h: 40 },
+        }),
+        node({
+          id: 3,
+          parentId: 2,
+          role: "img",
+          tag: "svg",
+          attrs: { "aria-label": "Filter rows", class: "kocomz" },
+        }),
+      ]),
+    );
+
+    expect(out.text).toContain('@e1 button "Filter rows"');
+    expect(coreRefs(out.refs)).toEqual([{ ref: "e1", backendNodeId: 2 }]);
+  });
+
+  it("keeps a semantic image as evidence for its clickable wrapper", () => {
+    const out = renderVom(
+      scene([
+        node({ id: 1, role: "RootWebArea", name: "Doc" }),
+        node({
+          id: 2,
+          parentId: 1,
+          role: "generic",
+          cursor: "pointer",
+          rect: { x: 20, y: 20, w: 40, h: 40 },
+        }),
+        node({
+          id: 3,
+          parentId: 2,
+          role: "img",
+          name: "Account",
+          cursor: "pointer",
+          tag: "div",
+        }),
+      ]),
+    );
+
+    expect(out.text).toContain('@e1 button "Account"');
+    expect(coreRefs(out.refs)).toEqual([{ ref: "e1", backendNodeId: 2 }]);
+  });
+
   it("keeps the deepest custom control when wrapper and child both look clickable", () => {
     const out = renderVom(
       scene([

packages/vom/src/index.ts

@@ -1,4 +1,9 @@
-export { applyVomInteractionRecovery, isVomReferenceNode, renderVom } from "./render";
+export {
+  applyVomInteractionRecovery,
+  isVomReferenceNode,
+  isVomStructuralRole,
+  renderVom,
+} from "./render";
 export type {
   ActiveScopeBlock,
   BlockingLayer,
@@ -10,6 +15,8 @@ export type {
   VomNode,
   VomOptions,
   VomRef,
+  VomRefCapability,
   VomResult,
   VomScene,
+  VomVisualSurface,
 } from "./types";

packages/vom/src/render.ts

@@ -9,6 +9,7 @@ import type {
   VomOptions,
   VomResult,
   VomScene,
+  VomVisualSurface,
 } from "./types";
 
 const SKIP_ROLES = new Set(["generic", "none", "presentation", "inlinetextbox"]);
@@ -75,6 +76,10 @@ const STRUCTURAL_ROLES = new Set([
   "webarea",
 ]);
 
+export function isVomStructuralRole(role: string | undefined): boolean {
+  return STRUCTURAL_ROLES.has(role?.toLowerCase() ?? "");
+}
+
 const SENSITIVE_MASK = "•••";
 const DEFAULT_MAX_DEPTH = Number.POSITIVE_INFINITY;
 const DEFAULT_MAX_TOKENS = Number.POSITIVE_INFINITY;
@@ -193,13 +198,16 @@ function shouldRender(node: VomNode): boolean {
   const role = normalizedRole(node);
   if (SKIP_ROLES.has(role)) return false;
   if (INTERACTIVE_ROLES.has(role)) return true;
-  if (STRUCTURAL_ROLES.has(role)) return true;
+  if (isVomStructuralRole(role)) return true;
 
   return cleaned(node.name) !== undefined;
 }
 
 export function isVomReferenceNode(node: VomNode): boolean {
-  return INTERACTIVE_ROLES.has(normalizedRole(node)) || isUrlBearingStructuralAction(node);
+  return (
+    node.referenceable !== false &&
+    (INTERACTIVE_ROLES.has(normalizedRole(node)) || isUrlBearingStructuralAction(node))
+  );
 }
 
 function hasRecoveryHandler(node: VomNode): boolean {
@@ -219,14 +227,30 @@ function isContentEditable(node: VomNode): boolean {
   return contentEditable === "true" || contentEditable === "plaintext-only";
 }
 
-function iconKeyword(value: string | undefined): string | undefined {
-  const cleanedValue = cleaned(value);
-  if (!cleanedValue) return undefined;
-  const last = cleanedValue
-    .split(/[#/.\s:_-]+/)
+const ICON_REFERENCE_MARKERS = new Set(["glyph", "icon", "icons", "symbol"]);
+const ICON_REFERENCE_DECORATORS = new Set(["fill", "filled", "line", "outline", "outlined"]);
+
+function iconReferenceName(value: string | undefined): string | undefined {
+  const reference = cleaned(value);
+  if (!reference) return undefined;
+  const fragment = reference.includes("#") ? reference.slice(reference.lastIndexOf("#") + 1) : "";
+  const tokens = (fragment || reference)
+    ?.split(/[#/.\s:_-]+/)
     .filter(Boolean)
-    .pop();
-  return last && /^[a-z][a-z0-9_-]{1,32}$/i.test(last) ? last.toLowerCase() : undefined;
+    .map((token) => token.toLowerCase());
+  if (tokens.length === 0) return undefined;
+  if (fragment) {
+    const semanticTokens = tokens.filter(
+      (token) => !ICON_REFERENCE_MARKERS.has(token) && !ICON_REFERENCE_DECORATORS.has(token),
+    );
+    return semanticTokens.length > 0 ? semanticTokens.join(" ") : undefined;
+  }
+  const marker = tokens.findLastIndex((token) => ICON_REFERENCE_MARKERS.has(token));
+  if (marker < 0) return undefined;
+  const semanticTokens = tokens
+    .slice(marker + 1)
+    .filter((token) => !ICON_REFERENCE_DECORATORS.has(token));
+  return semanticTokens.length > 0 ? semanticTokens.join(" ") : undefined;
 }
 
 function iconHintFromSubtree(
@@ -238,12 +262,12 @@ function iconHintFromSubtree(
   for (const child of children.get(node.id) ?? []) {
     const attrs = child.attrs ?? {};
     const hint =
-      iconKeyword(attrs["aria-label"]) ??
-      iconKeyword(attrs.title) ??
-      iconKeyword(attrs.href) ??
-      iconKeyword(attrs["xlink:href"]) ??
-      iconKeyword(attrs.class) ??
-      iconKeyword(child.text);
+      cleaned(attrs["aria-label"]) ??
+      cleaned(attrs.title) ??
+      (normalizedRole(child) === "img" ? cleaned(child.name) : undefined) ??
+      (["img", "svg", "use"].includes(normalizedTag(child))
+        ? (iconReferenceName(attrs.href) ?? iconReferenceName(attrs["xlink:href"]))
+        : undefined);
     if (hint) return hint;
     const nested = iconHintFromSubtree(child, children, depth + 1);
     if (nested) return nested;
@@ -269,6 +293,7 @@ function recoveredRole(
   node: VomNode,
   children?: Map<number | null, VomNode[]>,
 ): string | undefined {
+  const currentRole = normalizedRole(node);
   const explicitRole = node.attrs?.role?.toLowerCase() ?? "";
   const hasHandler = hasRecoveryHandler(node);
   const focusable = isFocusable(node);
@@ -290,7 +315,9 @@ function recoveredRole(
       : "button";
   }
   if (hasHandler && hasName) return "button";
-  if (node.cursor === "pointer" && hasName) return "button";
+  if ((!currentRole || SKIP_ROLES.has(currentRole)) && node.cursor === "pointer" && hasName) {
+    return "button";
+  }
   return undefined;
 }
 
@@ -711,6 +738,53 @@ interface RenderState {
   duplicateRefNames: Set<string>;
   surfaceMap: Map<number, CondSurface>;
   scopeMap: Map<number, ActiveScopeBlock>;
+  visualSurfaces: Map<number | null, VomVisualSurface[]>;
+}
+
+function groupedByParent<T extends { parentId: number | null }>(
+  items: T[],
+): Map<number | null, T[]> {
+  const grouped = new Map<number | null, T[]>();
+  for (const item of items) {
+    const siblings = grouped.get(item.parentId) ?? [];
+    siblings.push(item);
+    grouped.set(item.parentId, siblings);
+  }
+  return grouped;
+}
+
+function emitVisualEntries(parentId: number | null, depth: number, state: RenderState): void {
+  if (state.stopped) return;
+  for (const surface of state.visualSurfaces.get(parentId) ?? []) {
+    if (depth > state.maxDepth) {
+      state.truncated = true;
+      continue;
+    }
+    const ref = `e${state.nextRef}`;
+    const label = cleaned(surface.label) ?? `${surface.renderingKind} visual surface`;
+    const layers = surface.memberCount > 1 ? `; layers=${surface.memberCount}` : "";
+    const line = `${"  ".repeat(depth)}@${ref} surface ${JSON.stringify(label)} [rendering=${surface.renderingKind}${layers}; visual-only; use: bsk screenshot --ref @${ref}]`;
+    const nextTokens = state.tokens + estimateTokens(line);
+    if (nextTokens > state.maxTokens) {
+      state.truncated = true;
+      state.stopped = true;
+      return;
+    }
+    state.lines.push(line);
+    state.tokens = nextTokens;
+    state.refs.push({
+      ref,
+      backendNodeId: surface.backendNodeId,
+      frameId: surface.frameId,
+      visibleRect: surface.visibleRect,
+      role: "surface",
+      name: label,
+      kind: "surface",
+      capabilities: ["screenshot"],
+      line: state.lines.length - 1,
+    });
+    state.nextRef += 1;
+  }
 }
 
 function emitActiveScopeBlock(scope: ActiveScopeBlock, depth: number, state: RenderState): void {
@@ -786,6 +860,8 @@ function renderTree(
         ...(node.role ? { role: node.role } : {}),
         ...(name ? { name } : {}),
         ...(context.length > 0 ? { ctx: context.join(" > ") } : {}),
+        kind: "dom",
+        capabilities: ["interact", "screenshot"],
         line: state.lines.length - 1,
       });
       state.nextRef += 1;
@@ -795,10 +871,12 @@ function renderTree(
     if (scope) emitActiveScopeBlock(scope, depth + 1, state);
 
     if ((ref && shouldSkipRedundantRefChildren(node)) || shouldSkipRedundantChildren(node, state)) {
+      emitVisualEntries(node.id, depth + 1, state);
       continue;
     }
     renderTree(children, node.id, depth + 1, state);
   }
+  emitVisualEntries(parentId, depth, state);
 }
 
 function renderNodes(
@@ -807,6 +885,7 @@ function renderNodes(
   initialLines: string[],
   surfaces: CondSurface[] = [],
   activeScopeBlocks: ActiveScopeBlock[] = [],
+  visualSurfaces: VomVisualSurface[] = [],
 ): RenderState {
   const children = buildChildren(nodes);
   const state: RenderState = {
@@ -825,6 +904,7 @@ function renderNodes(
     duplicateRefNames: duplicateReferenceNames(nodes),
     surfaceMap: new Map(surfaces.map((surface) => [surface.triggerId, surface])),
     scopeMap: new Map(activeScopeBlocks.map((scope) => [scope.triggerId, scope])),
+    visualSurfaces: groupedByParent(visualSurfaces),
   };
 
   renderTree(children, null, 1, state);
@@ -1030,7 +1110,16 @@ function renderDoubleLayer(scene: VomScene, layer: BlockingLayer, options: VomOp
     "@layers 2 focus=L1",
     `L1 ${layer.kind} cover=${Math.round(layer.coverage * 100)}%`,
   ];
-  const state = renderNodes(visibleNodes, options, header, scene.surfaces, scene.activeScopeBlocks);
+  const visibleSurface = (parentId: number | null): boolean =>
+    parentId === null || included.has(parentId);
+  const state = renderNodes(
+    visibleNodes,
+    options,
+    header,
+    scene.surfaces,
+    scene.activeScopeBlocks,
+    scene.visualSurfaces?.filter((surface) => visibleSurface(surface.parentId)),
+  );
   state.lines.push(renderPageOcclusionLine(hiddenCount));
 
   return {
@@ -1058,6 +1147,7 @@ export function renderVom(scene: VomScene, options: VomOptions = {}): VomResult
     ],
     scene.surfaces,
     scene.activeScopeBlocks,
+    scene.visualSurfaces,
   );
 
   return {

packages/vom/src/types.ts

@@ -24,6 +24,8 @@ export interface VomNode {
   backendNodeId?: number;
   frameId?: string;
   contextScopeId?: string;
+  /** False for semantic-only nodes that cannot be addressed through CDP. */
+  referenceable?: boolean;
 
   role?: string;
   name?: string;
@@ -59,6 +61,8 @@ export interface VomScene {
   rootFrameId?: string;
   surfaces?: CondSurface[];
   activeScopeBlocks?: ActiveScopeBlock[];
+  /** Non-semantic rendered regions discovered alongside the AX/DOM tree. */
+  visualSurfaces?: VomVisualSurface[];
 }
 
 export interface VomOptions {
@@ -92,6 +96,22 @@ export interface VomRef {
   ref: string;
   backendNodeId: number;
   frameId?: string;
+  /** Observation-time top-viewport crop for screenshot-only surfaces. */
+  visibleRect?: Rect;
+  kind?: "dom" | "surface";
+  capabilities?: VomRefCapability[];
+}
+
+export type VomRefCapability = "interact" | "screenshot";
+
+export interface VomVisualSurface {
+  parentId: number | null;
+  backendNodeId: number;
+  frameId: string;
+  renderingKind: "canvas";
+  visibleRect: Rect;
+  label?: string;
+  memberCount: number;
 }
 
 export interface RenderedRef extends VomRef {

skill/SKILL.md

@@ -80,6 +80,8 @@ Prefer `@eN` refs from the latest snapshot over raw CSS selectors. Use `--ref` /
 
 When VOM renders `[hover first: …]` on an element, the listed items are not currently clickable refs. Run `bsk hover <that-ref> --session <id>`, then immediately run `bsk snapshot` or `bsk observe` again and click the newly visible menu item ref. Do not click the trigger itself unless the user explicitly wants the trigger action.
 
+When `bsk observe` renders `@eN surface ... [visual-only; ...]`, the ref identifies a rendered canvas surface, not an interactable DOM control. Use `bsk screenshot --ref @eN --session <id>` to inspect its visible crop. Do not pass a visual surface ref to click, fill, hover, or select; those commands intentionally reject screenshot-only refs.
+
 ## Observation priority
 
 Start with `bsk observe` to understand page structure, text, controls, element refs, and conditional hover/focus surfaces. Use `bsk snapshot` only when you need the stricter static accessibility tree or VOM is insufficient. Only escalate to raw HTML or screenshots when the latest observation cannot answer the question: