fix(callback_host): close orphaned helper page before opening on same WS connection

Sends sgHideBrowerserClosePage (best-effort) before sgHideBrowerserOpenPage
on the same bootstrap WebSocket connection. This prevents duplicate helper
pages across process restarts. Also enables hidden domain mode so the helper
page is not visible to users.

🤖 Generated with [Qoder][https://qoder.com]

src/browser/callback_host.rs

@@ -357,11 +357,17 @@ fn bootstrap_helper_page(
         ))
         .map_err(|err| PipeError::Protocol(format!("browser websocket register failed: {err}")))?;
     let _ = recv_bootstrap_prelude(&mut websocket);
-    let open_action = if use_hidden_domain {
-        "sgHideBrowerserOpenPage"
+
+    // Close any orphaned helper page from a previous process run.
+    // Best-effort: if no page exists, the browser silently ignores this.
+    let (open_action, close_action) = if use_hidden_domain {
+        ("sgHideBrowerserOpenPage", "sgHideBrowerserClosePage")
     } else {
-        "sgBrowerserOpenPage"
+        ("sgBrowerserOpenPage", "sgBrowserClosePage")
     };
+    let close_payload = json!([request_url, close_action, helper_url]).to_string();
+    let _ = websocket.send(Message::Text(close_payload.into()));
+
     let payload = json!([
         request_url,
         open_action,

src/service/server.rs

@@ -287,7 +287,7 @@ pub(crate) fn serve_client(
                         &bootstrap_url,
                         Duration::from_secs(15),
                         BROWSER_RESPONSE_TIMEOUT,
-                        false, // use_hidden_domain: visible tab for now
+                        true, // use_hidden_domain: hidden domain for invisible helper
                     ) {
                         Ok(host) => {
                             *cached_host = Some(Arc::new(host));