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+# Helper Page Lifecycle Fix & Hidden Domain Support — Implementation Plan
+
+> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** Fix duplicate browser-helper.html pages caused by WebSocket reconnections, add cleanup on Drop, and introduce a config switch for hidden-domain page opening.
+
+**Architecture:** Three changes: (1) lift `cached_host` from `serve_client()` to the outer `run()` loop so reconnections share one host, (2) enhance `Drop for LiveBrowserCallbackHost` to send a close-page command via browser WS, (3) add `use_hidden_domain: bool` parameter that selects between `sgBrowerserOpenPage`/`sgHideBrowerserOpenPage` and their corresponding close APIs.
+
+**Tech Stack:** Rust, tungstenite WebSocket crate, SuperRPA browser WS protocol
+
+---
+
+### Task 1: Add `use_hidden_domain` field and update `bootstrap_helper_page`
+
+**Files:**
+- Modify: `src/browser/callback_host.rs:28` (constant), `:44-51` (struct), `:215-252` (constructor), `:340-359` (bootstrap fn)
+
+- [ ] **Step 1: Change `HELPER_BOOTSTRAP_ACTION` from constant to a function of `use_hidden_domain`**
+
+Replace the constant and update `bootstrap_helper_page` to accept and use the flag:
+
+```rust
+// DELETE this line:
+// const HELPER_BOOTSTRAP_ACTION: &str = "sgBrowerserOpenPage";
+
+// REPLACE bootstrap_helper_page signature and body:
+fn bootstrap_helper_page(
+    browser_ws_url: &str,
+    request_url: &str,
+    helper_url: &str,
+    use_hidden_domain: bool,
+) -> Result<(), PipeError> {
+    let (mut websocket, _) = connect(browser_ws_url)
+        .map_err(|err| PipeError::Protocol(format!("browser websocket connect failed: {err}")))?;
+    configure_bootstrap_socket(&mut websocket)?;
+    websocket
+        .send(Message::Text(
+            r#"{"type":"register","role":"web"}"#.to_string().into(),
+        ))
+        .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"
+    } else {
+        "sgBrowerserOpenPage"
+    };
+    let payload = json!([
+        request_url,
+        open_action,
+        helper_url,
+    ])
+    .to_string();
+    websocket
+        .send(Message::Text(payload.into()))
+        .map_err(|err| PipeError::Protocol(format!("helper bootstrap send failed: {err}")))?;
+    Ok(())
+}
+```
+
+- [ ] **Step 2: Add new fields to `LiveBrowserCallbackHost`**
+
+```rust
+#[derive(Debug)]
+pub(crate) struct LiveBrowserCallbackHost {
+    host: Arc<BrowserCallbackHost>,
+    shutdown: Arc<AtomicBool>,
+    server_thread: Mutex<Option<JoinHandle<()>>>,
+    command_lock: Mutex<()>,
+    result_timeout: Duration,
+    browser_ws_url: String,
+    use_hidden_domain: bool,
+}
+```
+
+- [ ] **Step 3: Update `start_with_browser_ws_url` to accept and store the new parameter**
+
+```rust
+impl LiveBrowserCallbackHost {
+    pub(crate) fn start_with_browser_ws_url(
+        browser_ws_url: &str,
+        bootstrap_request_url: &str,
+        ready_timeout: Duration,
+        result_timeout: Duration,
+        use_hidden_domain: bool,
+    ) -> Result<Self, PipeError> {
+        let listener = TcpListener::bind("127.0.0.1:0").map_err(|err| {
+            PipeError::Protocol(format!("failed to bind callback host listener: {err}"))
+        })?;
+        listener.set_nonblocking(true).map_err(|err| {
+            PipeError::Protocol(format!("failed to configure callback host listener: {err}"))
+        })?;
+        let origin = format!(
+            "http://{}",
+            listener.local_addr().map_err(|err| {
+                PipeError::Protocol(format!(
+                    "failed to resolve callback host listener address: {err}"
+                ))
+            })?
+        );
+        let host = Arc::new(BrowserCallbackHost::with_urls(&origin, browser_ws_url));
+        let shutdown = Arc::new(AtomicBool::new(false));
+        let thread_host = host.clone();
+        let thread_shutdown = shutdown.clone();
+        let server_thread = thread::spawn(move || serve_loop(listener, thread_host, thread_shutdown));
+
+        bootstrap_helper_page(browser_ws_url, bootstrap_request_url, host.helper_url(), use_hidden_domain)?;
+        wait_for_helper_ready(host.as_ref(), ready_timeout)?;
+
+        let live_host = Self {
+            host,
+            shutdown,
+            server_thread: Mutex::new(Some(server_thread)),
+            command_lock: Mutex::new(()),
+            result_timeout,
+            browser_ws_url: browser_ws_url.to_string(),
+            use_hidden_domain,
+        };
+        Ok(live_host)
+    }
+```
+
+- [ ] **Step 4: Fix the inline test struct literal that constructs `LiveBrowserCallbackHost` directly**
+
+In the `live_callback_host_treats_simulated_mouse_command_as_fire_and_forget` test (around line 1110), add the new fields:
+
+```rust
+        let host = LiveBrowserCallbackHost {
+            host: Arc::new(BrowserCallbackHost::new()),
+            shutdown: Arc::new(AtomicBool::new(false)),
+            server_thread: Mutex::new(None),
+            command_lock: Mutex::new(()),
+            result_timeout: Duration::from_millis(10),
+            browser_ws_url: "ws://127.0.0.1:12345".to_string(),
+            use_hidden_domain: false,
+        };
+```
+
+- [ ] **Step 5: Run build to verify compilation**
+
+Run: `cargo build 2>&1`
+Expected: 0 errors. The `HELPER_BOOTSTRAP_ACTION` constant removal and signature changes should all be internally consistent.
+
+- [ ] **Step 6: Run tests to verify existing behavior is preserved**
+
+Run: `cargo test -- callback_host 2>&1`
+Expected: All existing callback_host tests pass (including `live_callback_host_sends_bootstrap_open_page_command` which still checks for `sgBrowerserOpenPage` since no caller passes `true` yet).
+
+- [ ] **Step 7: Commit**
+
+```bash
+git add src/browser/callback_host.rs
+git commit -m "feat(callback_host): add use_hidden_domain param to bootstrap_helper_page"
+```
+
+---
+
+### Task 2: Enhance `Drop` to close the helper page
+
+**Files:**
+- Modify: `src/browser/callback_host.rs:321-328` (Drop impl)
+
+- [ ] **Step 1: Add `close_helper_page` helper function**
+
+Add this function near `bootstrap_helper_page` (after line ~360):
+
+```rust
+/// Best-effort attempt to close the helper page tab via browser WebSocket.
+/// Silently ignores all errors — this runs during Drop and must not panic.
+fn close_helper_page(browser_ws_url: &str, helper_url: &str, use_hidden_domain: bool) {
+    let close_action = if use_hidden_domain {
+        "sgHideBrowerserClosePage"
+    } else {
+        "sgBrowserClosePage"
+    };
+
+    let result: Result<(), Box<dyn std::error::Error>> = (|| {
+        // Use a raw TcpStream with timeouts instead of tungstenite::connect
+        // which does not expose a connection timeout.
+        let addr = browser_ws_url
+            .trim_start_matches("ws://")
+            .trim_start_matches("wss://");
+        let stream = TcpStream::connect_timeout(
+            &addr.parse().map_err(|e| format!("addr parse: {e}"))?,
+            Duration::from_millis(100),
+        )?;
+        stream.set_read_timeout(Some(Duration::from_millis(200)))?;
+        stream.set_write_timeout(Some(Duration::from_millis(200)))?;
+        let (mut websocket, _) = tungstenite::client(
+            browser_ws_url,
+            stream,
+        )?;
+        websocket.send(Message::Text(
+            r#"{"type":"register","role":"web"}"#.to_string().into(),
+        ))?;
+        // Drain the welcome prelude (best-effort, ignore timeout).
+        let _ = websocket.read();
+        let payload = json!([helper_url, close_action, helper_url]).to_string();
+        websocket.send(Message::Text(payload.into()))?;
+        Ok(())
+    })();
+
+    if let Err(err) = result {
+        eprintln!("close_helper_page best-effort failed (harmless): {err}");
+    }
+}
+```
+
+- [ ] **Step 2: Update `Drop for LiveBrowserCallbackHost` to call `close_helper_page`**
+
+```rust
+impl Drop for LiveBrowserCallbackHost {
+    fn drop(&mut self) {
+        // Best-effort: tell the browser to close the helper page tab.
+        close_helper_page(
+            &self.browser_ws_url,
+            self.host.helper_url(),
+            self.use_hidden_domain,
+        );
+
+        self.shutdown.store(true, Ordering::Relaxed);
+        if let Some(handle) = self.server_thread.lock().unwrap().take() {
+            let _ = handle.join();
+        }
+    }
+}
+```
+
+- [ ] **Step 3: Run build to verify compilation**
+
+Run: `cargo build 2>&1`
+Expected: 0 errors. `close_helper_page` uses types already imported (`TcpStream`, `Duration`, `json!`, `Message`).
+
+- [ ] **Step 4: Run tests**
+
+Run: `cargo test -- callback_host 2>&1`
+Expected: All pass. The Drop enhancement is best-effort and the test helper constructs hosts with `server_thread: Mutex::new(None)`, so Drop completes cleanly.
+
+- [ ] **Step 5: Commit**
+
+```bash
+git add src/browser/callback_host.rs
+git commit -m "feat(callback_host): close helper page on Drop via browser WS"
+```
+
+---
+
+### Task 3: Lift `cached_host` to outer loop and update `serve_client` signature
+
+**Files:**
+- Modify: `src/service/mod.rs:72-96` (run loop)
+- Modify: `src/service/server.rs:232-241` (serve_client signature and cached_host init)
+
+- [ ] **Step 1: Change `serve_client` to accept `cached_host` as a parameter**
+
+In `src/service/server.rs`, change the function signature and remove the local `cached_host` variable:
+
+```rust
+pub fn serve_client(
+    context: &AgentRuntimeContext,
+    session: &ServiceSession,
+    sink: Arc<ServiceEventSink>,
+    browser_ws_url: &str,
+    mac_policy: &MacPolicy,
+    cached_host: &mut Option<Arc<LiveBrowserCallbackHost>>,
+) -> Result<(), PipeError> {
+    // DELETE the line: let mut cached_host: Option<Arc<LiveBrowserCallbackHost>> = None;
+
+    loop {
+        // ... rest of function body unchanged, `cached_host` is now the parameter
+```
+
+The body references to `cached_host` remain identical — they just operate on the borrowed mutable reference instead of a local variable.
+
+- [ ] **Step 2: Update `start_with_browser_ws_url` call to pass `false` for `use_hidden_domain`**
+
+In `src/service/server.rs`, at the `LiveBrowserCallbackHost::start_with_browser_ws_url` call (around line 288), add the `false` argument:
+
+```rust
+                    match LiveBrowserCallbackHost::start_with_browser_ws_url(
+                        browser_ws_url,
+                        &bootstrap_url,
+                        Duration::from_secs(15),
+                        BROWSER_RESPONSE_TIMEOUT,
+                        false, // use_hidden_domain: visible tab for now
+                    ) {
+```
+
+- [ ] **Step 3: Lift `cached_host` into `run()` in `mod.rs`**
+
+In `src/service/mod.rs`, declare `cached_host` before the loop and pass it to `serve_client`:
+
+```rust
+    // Add this import at the top of the function or file:
+    use crate::browser::callback_host::LiveBrowserCallbackHost;
+
+    // Before the loop (after line 64, after `let session = ...`):
+    let mut cached_host: Option<Arc<LiveBrowserCallbackHost>> = None;
+
+    loop {
+        let (stream, _) = listener.accept()?;
+        let websocket = accept(stream)
+            .map_err(|err| PipeError::Protocol(format!("service websocket accept failed: {err}")))?;
+        let sink = Arc::new(ServiceEventSink::from_websocket(websocket));
+        match session.try_attach_client() {
+            Ok(()) => {
+                let result = serve_client(
+                    &runtime_context,
+                    &session,
+                    sink.clone(),
+                    browser_ws_url,
+                    &mac_policy,
+                    &mut cached_host,
+                );
+                session.detach_client();
+                match result {
+                    Ok(()) | Err(PipeError::PipeClosed) => {}
+                    Err(err) => return Err(err),
+                }
+            }
+            Err(message) => {
+                sink.send_service_message(message)?;
+            }
+        }
+    }
+```
+
+- [ ] **Step 4: Update the `pub use` export if needed**
+
+Check `src/service/mod.rs:17`:
+```rust
+pub use server::{serve_client, ServiceEventSink, ServiceSession};
+```
+The signature change is compatible — `serve_client` is still public with an added parameter. Any external callers will get a compile error guiding them to add the parameter, which is the desired behavior.
+
+- [ ] **Step 5: Run build to verify compilation**
+
+Run: `cargo build 2>&1`
+Expected: 0 errors. If there are external test files calling `serve_client`, they will fail here and need the new parameter added.
+
+- [ ] **Step 6: Run full test suite**
+
+Run: `cargo test 2>&1`
+Expected: All tests pass. External test files that call `serve_client` indirectly through the service protocol tests should still work because they use the WS protocol layer, not `serve_client` directly. (Verified: grep found 0 test files referencing `serve_client` or `LiveBrowserCallbackHost`.)
+
+- [ ] **Step 7: Commit**
+
+```bash
+git add src/service/mod.rs src/service/server.rs
+git commit -m "fix(service): lift cached_host to outer loop to prevent duplicate helper pages"
+```
+
+---
+
+### Task 4: Add tests for hidden domain bootstrap
+
+**Files:**
+- Modify: `src/browser/callback_host.rs` (inline tests module, around line 1071)
+
+- [ ] **Step 1: Update existing `live_callback_host_sends_bootstrap_open_page_command` test**
+
+The test currently calls `start_with_browser_ws_url` with 4 args. Add the 5th arg `false`:
+
+```rust
+    #[test]
+    fn live_callback_host_sends_bootstrap_open_page_command() {
+        let (ws_url, frames, handle) = start_fake_browser_status_server();
+
+        let result = LiveBrowserCallbackHost::start_with_browser_ws_url(
+            &ws_url,
+            "https://www.zhihu.com",
+            Duration::from_millis(100),
+            Duration::from_millis(50),
+            false,
+        );
+        assert!(result.is_err(), "expected timeout because no real helper page loads");
+        drop(result);
+        handle.join().unwrap();
+
+        let sent = frames.lock().unwrap().clone();
+        assert!(
+            sent.iter().any(|frame| frame.contains("sgBrowerserOpenPage")),
+            "bootstrap should send sgBrowerserOpenPage to the browser WS; sent frames: {sent:?}"
+        );
+        assert!(
+            sent.iter().any(|frame| frame.contains("/sgclaw/browser-helper.html")),
+            "bootstrap should include the helper page URL; sent frames: {sent:?}"
+        );
+        assert!(
+            sent.iter().any(|frame| frame.contains("https://www.zhihu.com")),
+            "bootstrap requestUrl should be the provided page URL; sent frames: {sent:?}"
+        );
+    }
+```
+
+- [ ] **Step 2: Add new test for hidden domain bootstrap**
+
+Add this test after the existing one:
+
+```rust
+    #[test]
+    fn live_callback_host_hidden_domain_sends_hide_open_page_command() {
+        let (ws_url, frames, handle) = start_fake_browser_status_server();
+
+        let result = LiveBrowserCallbackHost::start_with_browser_ws_url(
+            &ws_url,
+            "https://www.zhihu.com",
+            Duration::from_millis(100),
+            Duration::from_millis(50),
+            true,
+        );
+        assert!(result.is_err(), "expected timeout because no real helper page loads");
+        drop(result);
+        handle.join().unwrap();
+
+        let sent = frames.lock().unwrap().clone();
+        assert!(
+            sent.iter().any(|frame| frame.contains("sgHideBrowerserOpenPage")),
+            "hidden domain bootstrap should send sgHideBrowerserOpenPage; sent frames: {sent:?}"
+        );
+        assert!(
+            !sent.iter().any(|frame| {
+                frame.contains("\"sgBrowerserOpenPage\"")
+            }),
+            "hidden domain bootstrap should NOT send visible sgBrowerserOpenPage; sent frames: {sent:?}"
+        );
+        assert!(
+            sent.iter().any(|frame| frame.contains("/sgclaw/browser-helper.html")),
+            "bootstrap should include the helper page URL; sent frames: {sent:?}"
+        );
+    }
+```
+
+- [ ] **Step 3: Run all callback_host tests**
+
+Run: `cargo test -- callback_host 2>&1`
+Expected: All 3 tests pass:
+- `live_callback_host_sends_bootstrap_open_page_command` — regression, visible domain
+- `live_callback_host_hidden_domain_sends_hide_open_page_command` — new, hidden domain
+- `live_callback_host_treats_simulated_mouse_command_as_fire_and_forget` — unchanged
+
+- [ ] **Step 4: Run full test suite**
+
+Run: `cargo test 2>&1`
+Expected: All tests pass.
+
+- [ ] **Step 5: Commit**
+
+```bash
+git add src/browser/callback_host.rs
+git commit -m "test(callback_host): add hidden domain bootstrap test"
+```
+
+---
+
+### Task 5: Full build verification
+
+**Files:** None (verification only)
+
+- [ ] **Step 1: Clean build**
+
+Run: `cargo build 2>&1`
+Expected: 0 errors. Warnings about dead code in unrelated modules are acceptable.
+
+- [ ] **Step 2: Full test suite**
+
+Run: `cargo test 2>&1`
+Expected: All tests pass. The pre-existing `lineloss_period_resolver_prompts_for_missing_period` failure (from previous work) is known and unrelated.
+
+- [ ] **Step 3: Verify the key behavioral changes in code**
+
+Manually confirm:
+1. `src/service/mod.rs` — `cached_host` is declared BEFORE the `loop`, not inside `serve_client`
+2. `src/browser/callback_host.rs` — `Drop::drop` calls `close_helper_page` before shutdown
+3. `src/browser/callback_host.rs` — `bootstrap_helper_page` uses `"sgHideBrowerserOpenPage"` when `use_hidden_domain == true` and `"sgBrowerserOpenPage"` when `false`
+4. `src/service/server.rs` — `start_with_browser_ws_url` call passes `false` as `use_hidden_domain`