@@ -3207,6 +3207,7 @@ describe("PreviewManager", () => {
         // which would leave the composer stuck on "Capturing…".
         const result = yield* Fiber.join(pick);
         expect(result?.annotation.screenshot).toBeNull();
+        expect(result?.screenshotFailed).toBe(true);
         expect(result?.submission).toBe("send");
         expect(webviewSend).toHaveBeenCalledWith("preview:annotation-captured");
       }),
 
@@ -2464,11 +2464,21 @@ const makeNativeOperations = Effect.fn("PreviewManager.makeOperations")(function
           const submission = args[2] === "send" ? "send" : "attach";
           runFork(
             captureAnnotationScreenshot(tabId, wc, cropRect).pipe(
+              // The renderer cannot tell a dropped crop from a comment-only
+              // pick by the null alone, so a failed or timed-out capture is
+              // flagged on the result.
               Effect.match({
-                onFailure: () => payload,
-                onSuccess: (screenshot) => ({ ...payload, screenshot }),
+                onFailure: (): PreviewAnnotationSubmissionResult => ({
+                  annotation: payload,
+                  submission,
+                  screenshotFailed: true,
+                }),
+                onSuccess: (screenshot): PreviewAnnotationSubmissionResult =>
+                  screenshot === null
+                    ? { annotation: payload, submission, screenshotFailed: true }
+                    : { annotation: { ...payload, screenshot }, submission },
               }),
-              Effect.flatMap((annotation) => {
+              Effect.flatMap((result) => {
                 // A capture that outlives its session must not touch the
                 // overlay: the preload tears down on the captured signal, and
                 // by now it may be running a newer pick.
@@ -2478,7 +2488,7 @@ const makeNativeOperations = Effect.fn("PreviewManager.makeOperations")(function
                   () => {
                     if (!wc.isDestroyed()) wc.send(ANNOTATION_CAPTURED_CHANNEL);
                   },
-                ).pipe(Effect.ignore, Effect.andThen(finishPick({ annotation, submission })));
+                ).pipe(Effect.ignore, Effect.andThen(finishPick(result)));
               }),
             ),
           );
 
@@ -252,6 +252,7 @@ vi.mock("~/browser/BrowserSurfaceSlot", () => ({ BrowserSurfaceSlot: () => null
 vi.mock("./usePreviewSession", () => ({ usePreviewSession: vi.fn() }));
 
 import { PreviewView, previewProfileName } from "./PreviewView";
+import { toastManager } from "~/components/ui/toast";
 import { previewRuntimeTabId } from "~/browser/previewRuntimeTabId";
 
 const TEST_THREAD_REF = {
@@ -342,6 +343,7 @@ describe("PreviewView navigation", () => {
     mocks.capturePreviewAnnotationScreenshot.mockReset();
     mocks.capturePreviewAnnotationScreenshot.mockResolvedValue({ status: "none" });
     mocks.addPreviewAnnotation.mockClear();
+    vi.mocked(toastManager.add).mockClear();
     mocks.addImage.mockClear();
     mocks.toggleAnnotation = null;
     mocks.pictureInPicture = false;
@@ -552,6 +554,38 @@ describe("PreviewView navigation", () => {
     expect(mocks.addPreviewAnnotation).toHaveBeenCalledWith(TEST_THREAD_REF, annotation);
   });
 
+  it("warns when main dropped the crop before handing over the pick", async () => {
+    const annotation = {
+      id: "annotation-3",
+      pageUrl: "https://example.com/dashboard",
+      pageTitle: "Dashboard",
+      comment: "Tighten this spacing",
+      elements: [],
+      regions: [],
+      strokes: [],
+      styleChanges: [],
+      screenshot: null,
+      createdAt: "2026-07-27T00:00:00.000Z",
+    };
+    const onSendAnnotation = vi.fn();
+    mocks.pickElement.mockResolvedValue({ annotation, submission: "send", screenshotFailed: true });
+
+    renderToStaticMarkup(
+      <PreviewView
+        threadRef={TEST_THREAD_REF}
+        tabId="tab-1"
+        visible
+        onSendAnnotation={onSendAnnotation}
+      />,
+    );
+    mocks.toggleAnnotation?.();
+
+    await vi.waitFor(() => expect(onSendAnnotation).toHaveBeenCalledWith(annotation, null));
+    // A null screenshot alone looks like a comment-only pick; the flag is what
+    // separates "no crop requested" from "crop lost to a timeout".
+    expect(toastManager.add).toHaveBeenCalledTimes(1);
+  });
+
   it("still sends when the picked element's crop cannot be captured", async () => {
     const annotation = {
       id: "annotation-2",
 
@@ -579,16 +579,19 @@ export function PreviewView({
       try {
         const result = await previewBridge.pickElement(runtimeTabId);
         if (!result) return;
-        const { annotation: picked, submission } = result;
+        const { annotation: picked, submission, screenshotFailed = false } = result;
         // The structured annotation is still sendable when its optional crop
         // stalls or fails, so tell the user what they lost and keep going
         // instead of holding the composer for an attachment that never lands.
         // The stored copy drops the screenshot on failure, otherwise the prompt
         // would tell the agent a crop is attached when none was sent.
         const capture = await capturePreviewAnnotationScreenshot(picked);
+        // Main reports a crop that failed or timed out on its side; the local
+        // conversion can fail too. Either way the user should hear about it.
+        const cropDropped = screenshotFailed || capture.status === "failed";
         const annotation = capture.status === "failed" ? { ...picked, screenshot: null } : picked;
         addPreviewAnnotation(threadRef, annotation);
-        if (capture.status === "failed") {
+        if (cropDropped) {
           toastManager.add(
             stackedThreadToast({
               type: "error",
 
@@ -934,11 +934,14 @@ export const PreviewAnnotationSubmissionSchema: Schema.Codec<PreviewAnnotationSu
 export interface PreviewAnnotationSubmissionResult {
   annotation: PreviewAnnotationPayload;
   submission: PreviewAnnotationSubmission;
+  /** The crop was requested but failed or timed out, so `annotation.screenshot` is null. */
+  screenshotFailed?: boolean;
 }
 export const PreviewAnnotationSubmissionResultSchema: Schema.Codec<PreviewAnnotationSubmissionResult> =
   Schema.Struct({
     annotation: PreviewAnnotationPayloadSchema,
     submission: PreviewAnnotationSubmissionSchema,
+    screenshotFailed: Schema.optionalKey(Schema.Boolean),
   });
 
 export const DesktopPreviewTabInputSchema = Schema.Struct({