diff --git a/crates/bili_sync/src/bilibili/danmaku/ass_writer.rs b/crates/bili_sync/src/bilibili/danmaku/ass_writer.rs
index 3adf1ae..b0f069b 100644
--- a/crates/bili_sync/src/bilibili/danmaku/ass_writer.rs
+++ b/crates/bili_sync/src/bilibili/danmaku/ass_writer.rs
@@ -184,7 +184,7 @@ impl<'a, W: AsyncWrite> AssWriter<'a, W> {
     }
 }
 
-fn escape_text(text: &str) -> Cow<str> {
+fn escape_text(text: &'_ str) -> Cow<'_, str> {
     let text = text.trim();
     if memchr::memchr(b'\n', text.as_bytes()).is_some() {
         Cow::from(text.replace('\n', "\\N"))
diff --git a/crates/bili_sync/src/bilibili/video.rs b/crates/bili_sync/src/bilibili/video.rs
index e8852f5..c92e9cb 100644
--- a/crates/bili_sync/src/bilibili/video.rs
+++ b/crates/bili_sync/src/bilibili/video.rs
@@ -91,7 +91,7 @@ impl<'a> Video<'a> {
             .collect())
     }
 
-    pub async fn get_danmaku_writer(&self, page: &'a PageInfo) -> Result<DanmakuWriter> {
+    pub async fn get_danmaku_writer(&self, page: &'a PageInfo) -> Result<DanmakuWriter<'a>> {
         let tasks = FuturesUnordered::new();
         for i in 1..=page.duration.div_ceil(360) {
             tasks.push(self.get_danmaku_segment(page, i as i64));
diff --git a/crates/bili_sync/src/task/http_server.rs b/crates/bili_sync/src/task/http_server.rs
index 307b6ee..dc72f22 100644
--- a/crates/bili_sync/src/task/http_server.rs
+++ b/crates/bili_sync/src/task/http_server.rs
@@ -26,7 +26,7 @@ pub async fn http_server(
     log_writer: LogHelper,
 ) -> Result<()> {
     let app = router()
-        .fallback_service(get(frontend_files))
+        .fallback_service(get(frontend_files).head(frontend_files))
         .layer(Extension(database_connection))
         .layer(Extension(bili_client))
         .layer(Extension(log_writer));
@@ -48,34 +48,51 @@ async fn frontend_files(request: Request) -> impl IntoResponse {
     };
     let mime_type = content.mime_type();
     let content_type = mime_type.as_deref().unwrap_or("application/octet-stream");
-    if cfg!(debug_assertions) {
-        (
-            [(header::CONTENT_TYPE, content_type)],
-            // safety: `RustEmbed` returns uncompressed files directly from the filesystem in debug mode
-            content.data().unwrap(),
-        )
-            .into_response()
-    } else {
-        let accepted_encodings = request
-            .headers()
-            .get(header::ACCEPT_ENCODING)
-            .and_then(|v| v.to_str().ok())
-            .map(|s| s.split(',').map(str::trim).collect::<HashSet<_>>())
-            .unwrap_or_default();
-        for (encoding, data) in [("br", content.data_br()), ("gzip", content.data_gzip())] {
-            if accepted_encodings.contains(encoding) {
-                if let Some(data) = data {
-                    return (
-                        [
-                            (header::CONTENT_TYPE, content_type),
-                            (header::CONTENT_ENCODING, encoding),
-                        ],
-                        data,
-                    )
-                        .into_response();
-                }
+    let default_headers = [
+        (header::CONTENT_TYPE, content_type),
+        (header::CACHE_CONTROL, "no-cache"),
+        (header::ETAG, &content.hash()),
+    ];
+    if let Some(if_none_match) = request.headers().get(header::IF_NONE_MATCH) {
+        if let Ok(client_etag) = if_none_match.to_str() {
+            if client_etag == content.hash() {
+                return (StatusCode::NOT_MODIFIED, default_headers).into_response();
             }
         }
-        "Unsupported Encoding".into_response()
     }
+    if request.method() == axum::http::Method::HEAD {
+        return (StatusCode::OK, default_headers).into_response();
+    }
+    if cfg!(debug_assertions) {
+        // safety: `RustEmbed` returns uncompressed files directly from the filesystem in debug mode
+        return (StatusCode::OK, default_headers, content.data().unwrap()).into_response();
+    }
+    let accepted_encodings = request
+        .headers()
+        .get(header::ACCEPT_ENCODING)
+        .and_then(|v| v.to_str().ok())
+        .map(|s| s.split(',').map(str::trim).collect::<HashSet<_>>())
+        .unwrap_or_default();
+    for (encoding, data) in [("br", content.data_br()), ("gzip", content.data_gzip())] {
+        if accepted_encodings.contains(encoding) {
+            if let Some(data) = data {
+                return (
+                    StatusCode::OK,
+                    [
+                        (header::CONTENT_TYPE, content_type),
+                        (header::CACHE_CONTROL, "no-cache"),
+                        (header::ETAG, &content.hash()),
+                        (header::CONTENT_ENCODING, encoding),
+                    ],
+                    data,
+                )
+                    .into_response();
+            }
+        }
+    }
+    (
+        StatusCode::NOT_ACCEPTABLE,
+        "Client must support gzip or brotli compression",
+    )
+        .into_response()
 }
diff --git a/crates/bili_sync/src/utils/task_notifier.rs b/crates/bili_sync/src/utils/task_notifier.rs
index c1009d8..4da2788 100644
--- a/crates/bili_sync/src/utils/task_notifier.rs
+++ b/crates/bili_sync/src/utils/task_notifier.rs
@@ -42,7 +42,7 @@ impl TaskStatusNotifier {
         }
     }
 
-    pub async fn start_running(&self) -> MutexGuard<()> {
+    pub async fn start_running(&'_ self) -> MutexGuard<'_, ()> {
         let lock = self.mutex.lock().await;
         let _ = self.tx.send(Arc::new(TaskStatus {
             is_running: true,