fix: 修复无信号状态同步与采集管线阻塞

- 使用非阻塞 V4L2 句柄并类型化采集错误
- 完善视频管线生命周期，避免复用停止中的管线
- 区分音视频事件并支持 REST/WebSocket 状态快照
- 修复信号丢失后保留最后一帧及刷新后黑屏问题
- 优化无信号提示、状态展示优先级及相关界面细节
- 降低重复 OTG 错误日志级别

src/events/mod.rs

@@ -6,9 +6,10 @@ use self::types::EXACT_EVENT_TOPICS;
 
 pub use types::{
     AtxDeviceInfo, AudioDeviceInfo, ClientStats, HidDeviceInfo, LedState, MsdDeviceInfo,
-    MsdDeviceMediaInfo, StreamDeviceLostKind, SystemEvent, TtydDeviceInfo, VideoDeviceInfo,
+    MsdDeviceMediaInfo, StreamKind, SystemEvent, TtydDeviceInfo, VideoDeviceInfo,
 };
 
+use std::sync::RwLock;
 use tokio::sync::broadcast;
 
 const EVENT_CHANNEL_CAPACITY: usize = 256;
@@ -40,6 +41,7 @@ pub struct EventBus {
     exact_topics: std::collections::HashMap<&'static str, broadcast::Sender<SystemEvent>>,
     prefix_topics: std::collections::HashMap<String, broadcast::Sender<SystemEvent>>,
     device_info_dirty_tx: broadcast::Sender<()>,
+    latest_video_stream_state: RwLock<Option<SystemEvent>>,
 }
 
 impl EventBus {
@@ -60,12 +62,26 @@ impl EventBus {
             exact_topics,
             prefix_topics,
             device_info_dirty_tx,
+            latest_video_stream_state: RwLock::new(None),
         }
     }
 
     pub fn publish(&self, event: SystemEvent) {
         let event_name = event.event_name();
 
+        if matches!(
+            event,
+            SystemEvent::StreamStateChanged {
+                kind: StreamKind::Video,
+                ..
+            }
+        ) {
+            *self
+                .latest_video_stream_state
+                .write()
+                .unwrap_or_else(|poisoned| poisoned.into_inner()) = Some(event.clone());
+        }
+
         if let Some(tx) = self.exact_topics.get(event_name) {
             let _ = tx.send(event.clone());
         }
@@ -103,6 +119,15 @@ impl EventBus {
         self.device_info_dirty_tx.subscribe()
     }
 
+    /// Stateful video status topics replay this value to new WebSocket
+    /// subscribers so a page refresh cannot miss an earlier signal-loss edge.
+    pub fn latest_video_stream_state(&self) -> Option<SystemEvent> {
+        self.latest_video_stream_state
+            .read()
+            .unwrap_or_else(|poisoned| poisoned.into_inner())
+            .clone()
+    }
+
     pub fn subscriber_count(&self) -> usize {
         self.tx.receiver_count()
     }
@@ -124,6 +149,7 @@ mod tests {
         let mut rx = bus.subscribe();
 
         bus.publish(SystemEvent::StreamStateChanged {
+            kind: StreamKind::Video,
             state: "streaming".to_string(),
             device: Some("/dev/video0".to_string()),
             reason: None,
@@ -132,6 +158,10 @@ mod tests {
 
         let event = rx.recv().await.unwrap();
         assert!(matches!(event, SystemEvent::StreamStateChanged { .. }));
+        assert!(matches!(
+            bus.latest_video_stream_state(),
+            Some(SystemEvent::StreamStateChanged { state, .. }) if state == "streaming"
+        ));
     }
 
     #[tokio::test]
@@ -143,6 +173,7 @@ mod tests {
         assert_eq!(bus.subscriber_count(), 2);
 
         bus.publish(SystemEvent::StreamStateChanged {
+            kind: StreamKind::Video,
             state: "ready".to_string(),
             device: Some("/dev/video0".to_string()),
             reason: None,
@@ -162,6 +193,7 @@ mod tests {
         let mut rx = bus.subscribe_topic("stream.state_changed").unwrap();
 
         bus.publish(SystemEvent::StreamStateChanged {
+            kind: StreamKind::Video,
             state: "ready".to_string(),
             device: None,
             reason: None,
@@ -178,6 +210,7 @@ mod tests {
         let mut rx = bus.subscribe_topic("stream.*").unwrap();
 
         bus.publish(SystemEvent::StreamStateChanged {
+            kind: StreamKind::Video,
             state: "ready".to_string(),
             device: None,
             reason: None,
@@ -200,10 +233,36 @@ mod tests {
         assert_eq!(bus.subscriber_count(), 0);
 
         bus.publish(SystemEvent::StreamStateChanged {
+            kind: StreamKind::Video,
             state: "ready".to_string(),
             device: None,
             reason: None,
             next_retry_ms: None,
         });
     }
+
+    #[test]
+    fn audio_state_does_not_replace_latest_video_state() {
+        let bus = EventBus::new();
+        bus.publish(SystemEvent::StreamStateChanged {
+            kind: StreamKind::Video,
+            state: "no_signal".to_string(),
+            device: Some("/dev/video0".to_string()),
+            reason: Some("no_sync".to_string()),
+            next_retry_ms: Some(500),
+        });
+        bus.publish(SystemEvent::StreamStateChanged {
+            kind: StreamKind::Audio,
+            state: "streaming".to_string(),
+            device: Some("hw:0,0".to_string()),
+            reason: None,
+            next_retry_ms: None,
+        });
+
+        assert!(matches!(
+            bus.latest_video_stream_state(),
+            Some(SystemEvent::StreamStateChanged { state, reason, .. })
+                if state == "no_signal" && reason.as_deref() == Some("no_sync")
+        ));
+    }
 }

src/events/types.rs

@@ -92,10 +92,10 @@ pub struct ClientStats {
     pub connected_secs: u64,
 }
 
-/// Video vs audio source for [`SystemEvent::StreamDeviceLost`] (WebSocket `stream.device_lost`).
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+/// Media subsystem that owns a stream state or device event.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize)]
 #[serde(rename_all = "snake_case")]
-pub enum StreamDeviceLostKind {
+pub enum StreamKind {
     Video,
     Audio,
 }
@@ -114,6 +114,7 @@ pub enum SystemEvent {
 
     #[serde(rename = "stream.state_changed")]
     StreamStateChanged {
+        kind: StreamKind,
         state: String,
         device: Option<String>,
         #[serde(skip_serializing_if = "Option::is_none")]
@@ -141,7 +142,7 @@ pub enum SystemEvent {
 
     #[serde(rename = "stream.device_lost")]
     StreamDeviceLost {
-        kind: StreamDeviceLostKind,
+        kind: StreamKind,
         device: String,
         reason: String,
     },
@@ -274,6 +275,7 @@ mod tests {
     #[test]
     fn test_event_name() {
         let event = SystemEvent::StreamStateChanged {
+            kind: StreamKind::Video,
             state: "streaming".to_string(),
             device: Some("/dev/video0".to_string()),
             reason: None,
@@ -285,7 +287,7 @@ mod tests {
     #[test]
     fn stream_device_lost_json_snake_case_kind() {
         let event = SystemEvent::StreamDeviceLost {
-            kind: StreamDeviceLostKind::Audio,
+            kind: StreamKind::Audio,
             device: "hw:0,0".to_string(),
             reason: "test".to_string(),
         };
@@ -306,6 +308,7 @@ mod tests {
                 from_mode: String::new(),
             },
             SystemEvent::StreamStateChanged {
+                kind: StreamKind::Video,
                 state: String::new(),
                 device: None,
                 reason: None,
@@ -323,7 +326,7 @@ mod tests {
                 fps: 0,
             },
             SystemEvent::StreamDeviceLost {
-                kind: StreamDeviceLostKind::Video,
+                kind: StreamKind::Video,
                 device: String::new(),
                 reason: String::new(),
             },