fix(mobile): preserve browser prompt replies across control updates

apps/mobile/src/features/browser/PreviewStreamWebView.tsx

@@ -26,6 +26,7 @@ import { AppText } from "../../components/AppText";
 import { downloadAndShareAttachment } from "../../lib/attachmentDownload";
 import { beginForegroundHandoff } from "../../lib/foreground-handoff";
 import { usePreviewStreamAccess } from "../../state/preview";
+import { previewPromptText } from "./previewPromptText";
 
 import {
   previewStreamDocument,
@@ -256,6 +257,7 @@ function PreviewStreamDocumentView({
   const [hostSetup, setHostSetup] = useState<PreviewStreamHostSetup | null>(null);
   const [started, setStarted] = useState(false);
   const [control, setControl] = useState<PreviewStreamControl | null>(null);
+  const dialogRef = useRef<PreviewStreamControl["dialog"]>(null);
   const [promptText, setPromptText] = useState("");
   const [fileChooser, setFileChooser] = useState<PreviewStreamFileChooser | null>(null);
   const answerFileChooser = (pick: boolean) => {
@@ -371,11 +373,14 @@ function PreviewStreamDocumentView({
           const message = previewStreamMessage(event.nativeEvent.data);
           if (message === null) return;
           switch (message.type) {
-            case "control":
+            case "control": {
               setControl(message);
-              setPromptText(message.dialog?.defaultValue ?? "");
+              const previousDialog = dialogRef.current;
+              dialogRef.current = message.dialog;
+              setPromptText((draft) => previewPromptText(previousDialog, message.dialog, draft));
               onControl?.(message);
               return;
+            }
             case "unauthorized":
               if (!onUnauthorized()) {
                 fail("This session can't open the browser stream. Reconnect to try again.");
@@ -413,6 +418,8 @@ function PreviewStreamDocumentView({
               }
               setStatus(message.status);
               if (message.status === "connecting") {
+                // Dialogs may have closed and reopened while this viewer was disconnected.
+                dialogRef.current = null;
                 setControl(null);
                 onControl?.(null);
               }

apps/mobile/src/features/browser/previewPromptText.test.ts

@@ -0,0 +1,41 @@
+import { describe, expect, it } from "vite-plus/test";
+
+import { previewPromptText } from "./previewPromptText";
+
+describe("browser prompt response", () => {
+  const prompt = { type: "prompt" as const, message: "Your name?", defaultValue: "Guest" };
+
+  it("preserves a typed response across repeated control broadcasts", () => {
+    expect(previewPromptText(prompt, { ...prompt }, "Alice")).toBe("Alice");
+  });
+
+  it("preserves an intentionally empty response", () => {
+    expect(previewPromptText(prompt, { ...prompt }, "")).toBe("");
+  });
+
+  it("initializes a newly opened prompt", () => {
+    expect(previewPromptText(null, prompt, "")).toBe("Guest");
+  });
+
+  it("resets a stale draft after reconnecting without dialog history", () => {
+    expect(previewPromptText(null, prompt, "Alice")).toBe("Guest");
+  });
+
+  it("resets when the message changes", () => {
+    expect(previewPromptText(prompt, { ...prompt, message: "Next name?" }, "Alice")).toBe("Guest");
+  });
+
+  it("resets when the default value changes", () => {
+    expect(previewPromptText(prompt, { ...prompt, defaultValue: "Bob" }, "Alice")).toBe("Bob");
+  });
+
+  it("resets when the dialog type changes with matching message and default", () => {
+    expect(previewPromptText(prompt, { ...prompt, type: "confirm" }, "Alice")).toBe("Guest");
+  });
+
+  it("clears a closed dialog and initializes an identical reopened prompt", () => {
+    const cleared = previewPromptText(prompt, null, "Alice");
+    expect(cleared).toBe("");
+    expect(previewPromptText(null, prompt, cleared)).toBe("Guest");
+  });
+});

apps/mobile/src/features/browser/previewPromptText.ts

@@ -0,0 +1,15 @@
+import type { PreviewStreamControl } from "@t3tools/client-runtime/preview/server-browser-stream";
+
+type Dialog = PreviewStreamControl["dialog"];
+
+/** Updates the native response draft when a browser control message arrives. */
+export function previewPromptText(previous: Dialog, next: Dialog, draft: string) {
+  if (
+    next?.type !== previous?.type ||
+    next?.message !== previous?.message ||
+    next?.defaultValue !== previous?.defaultValue
+  ) {
+    return next?.defaultValue ?? "";
+  }
+  return draft;
+}