fix(crawler): unhang shutdown on lingering Arc<Browser>, silence WS noise (0.43.1)

- Handle::close aborts its chromiumoxide driver task when another
  Arc<Browser> outlives the call, so shutdown returns instead of
  hanging on a stream that never terminates. Generic close_or_abort
  helper with regression tests covering both Arc paths.
- daemon.shutdown() is wrapped in a 5s timeout in main as defense
  in depth.
- Default RUST_LOG silences chromiumoxide::conn / chromiumoxide::handler
  WS-deserialize ERROR spam.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/Cargo.lock

@@ -1470,7 +1470,7 @@ checksum = "c41e0c4fef86961ac6d6f8a82609f55f31b05e4fce149ac5710e439df7619ba4"
 
 [[package]]
 name = "mangalord"
-version = "0.43.0"
+version = "0.43.1"
 dependencies = [
  "anyhow",
  "argon2",

backend/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "mangalord"
-version = "0.43.0"
+version = "0.43.1"
 edition = "2021"
 default-run = "mangalord"
 

backend/src/crawler/browser.rs

@@ -121,29 +121,50 @@ impl Handle {
     }
 
     /// Closes the browser and awaits the driver task. If other Arcs to
-    /// the browser are still alive we fall back to drop-kills-Chromium
-    /// semantics and just join the driver — this is the rare case where
-    /// shutdown raced an outstanding worker; the OS-level kill is the
-    /// safety net.
+    /// the browser are still alive we can't issue a clean CDP `close`,
+    /// so we abort the driver task instead — otherwise `handler.next()`
+    /// keeps polling forever and `Handle::close` hangs (chromiumoxide's
+    /// handler stream doesn't end on its own when the underlying WS
+    /// dies). Chromium itself is reaped by kill-on-drop once the last
+    /// `Arc<Browser>` is dropped.
     pub async fn close(self) -> anyhow::Result<()> {
-        match Arc::try_unwrap(self.browser) {
-            Ok(mut owned) => {
-                let _ = owned.close().await;
-                let _ = owned.wait().await;
-            }
-            Err(shared) => {
-                tracing::warn!(
-                    strong_count = Arc::strong_count(&shared),
-                    "Handle::close while Arc<Browser> still shared — relying on kill-on-drop"
-                );
-                drop(shared);
-            }
-        }
-        let _ = self.driver.await;
+        close_or_abort(self.browser, self.driver, |mut owned| async move {
+            let _ = owned.close().await;
+            let _ = owned.wait().await;
+        })
+        .await;
         Ok(())
     }
 }
 
+/// Shutdown core for [`Handle::close`], extracted so it can be unit-
+/// tested without launching real Chromium. When `arc` is uniquely owned,
+/// `on_owned` runs against the owned value and the driver is awaited
+/// normally. When other Arc holders exist, the driver is aborted before
+/// awaiting it so shutdown returns promptly.
+async fn close_or_abort<T, F, Fut>(arc: Arc<T>, driver: JoinHandle<()>, on_owned: F)
+where
+    T: Send + 'static,
+    F: FnOnce(T) -> Fut + Send,
+    Fut: std::future::Future<Output = ()> + Send,
+{
+    match Arc::try_unwrap(arc) {
+        Ok(owned) => {
+            on_owned(owned).await;
+            let _ = driver.await;
+        }
+        Err(shared) => {
+            tracing::warn!(
+                strong_count = Arc::strong_count(&shared),
+                "Handle::close while Arc still shared — aborting driver, relying on kill-on-drop"
+            );
+            drop(shared);
+            driver.abort();
+            let _ = driver.await;
+        }
+    }
+}
+
 /// Launches Chromium. Downloads it on first run via the `fetcher`
 /// feature; subsequent runs hit the cache. The cache dir is
 /// `$CRAWLER_CHROMIUM_DIR` if set, else `$HOME/.cache/mangalord/chromium`,
@@ -261,4 +282,54 @@ mod tests {
         assert_eq!(LaunchOptions::headless().mode, BrowserMode::Headless);
         assert_eq!(LaunchOptions::headed().mode, BrowserMode::Headed);
     }
+
+    // Regression: if another Arc<Browser> outlives `Handle::close`, the
+    // old code awaited the driver task forever because the chromiumoxide
+    // handler stream doesn't return None on its own. Aborting the driver
+    // unblocks shutdown even when kill-on-drop can't fire yet.
+    #[tokio::test]
+    async fn close_or_abort_returns_when_arc_is_shared() {
+        use std::sync::atomic::{AtomicBool, Ordering};
+        use std::time::Duration;
+
+        let arc = Arc::new(());
+        let _keepalive = Arc::clone(&arc); // forces try_unwrap to fail
+        let driver = tokio::spawn(std::future::pending::<()>());
+        let on_owned_ran = Arc::new(AtomicBool::new(false));
+
+        let flag = Arc::clone(&on_owned_ran);
+        let fut = close_or_abort(arc, driver, move |_| {
+            let flag = Arc::clone(&flag);
+            async move { flag.store(true, Ordering::Release) }
+        });
+
+        tokio::time::timeout(Duration::from_secs(2), fut)
+            .await
+            .expect("close_or_abort must not hang when driver is pending and Arc is shared");
+        assert!(
+            !on_owned_ran.load(Ordering::Acquire),
+            "on_owned must not run when the Arc is still shared"
+        );
+    }
+
+    #[tokio::test]
+    async fn close_or_abort_runs_on_owned_when_arc_is_unique() {
+        use std::sync::atomic::{AtomicBool, Ordering};
+
+        let arc = Arc::new(());
+        let driver = tokio::spawn(async {}); // completes immediately
+        let on_owned_ran = Arc::new(AtomicBool::new(false));
+
+        let flag = Arc::clone(&on_owned_ran);
+        close_or_abort(arc, driver, move |_| {
+            let flag = Arc::clone(&flag);
+            async move { flag.store(true, Ordering::Release) }
+        })
+        .await;
+
+        assert!(
+            on_owned_ran.load(Ordering::Acquire),
+            "on_owned must run when the Arc is unique"
+        );
+    }
 }

backend/src/main.rs

@@ -1,12 +1,21 @@
 use std::net::SocketAddr;
+use std::time::Duration;
 use tracing_subscriber::EnvFilter;
 
+/// Upper bound on how long we're willing to wait for the crawler daemon
+/// to drain before letting `main` return. Without it a wedged background
+/// task (e.g. a chromiumoxide handler stuck on a dead WS) blocks the
+/// process from exiting after Ctrl-C / SIGTERM.
+const CRAWLER_SHUTDOWN_TIMEOUT: Duration = Duration::from_secs(5);
+
 #[tokio::main]
 async fn main() -> anyhow::Result<()> {
     dotenvy::dotenv().ok();
     tracing_subscriber::fmt()
         .with_env_filter(
-            EnvFilter::try_from_default_env().unwrap_or_else(|_| "info,mangalord=debug".into()),
+            EnvFilter::try_from_default_env().unwrap_or_else(|_| {
+                "info,mangalord=debug,chromiumoxide::conn=off,chromiumoxide::handler=off".into()
+            }),
         )
         .init();
 
@@ -21,9 +30,18 @@ async fn main() -> anyhow::Result<()> {
         .await?;
 
     // Drain background tasks (crawler daemon) before exiting so Chromium
-    // gets a clean shutdown rather than relying on kill-on-drop.
+    // gets a clean shutdown rather than relying on kill-on-drop. Bounded
+    // by a timeout so a wedged shutdown path can't trap the process.
     if let Some(d) = daemon {
-        d.shutdown().await;
+        if tokio::time::timeout(CRAWLER_SHUTDOWN_TIMEOUT, d.shutdown())
+            .await
+            .is_err()
+        {
+            tracing::warn!(
+                timeout_s = CRAWLER_SHUTDOWN_TIMEOUT.as_secs(),
+                "crawler daemon shutdown exceeded timeout; abandoning"
+            );
+        }
     }
     Ok(())
 }