fix(beszel): improve live subscription error handling and cleanup

- Surface subscription errors in useLiveStats via onError + error state
- Show error UI in live mode when SSE connection fails
- Abort SSE reader on subscribeTopic failure instead of silent log
- Guard mock realtime against pre-aborted signal to prevent interval leak
- Remove dead includeDocker from subscription input schema

packages/api/src/router/widgets/beszel.ts

@@ -154,7 +154,6 @@ export const beszelRouter = createTRPCRouter({
     .input(
       z.object({
         systemId: z.string(),
-        includeDocker: z.boolean().default(true),
       }),
     )
     .subscription(({ ctx, input }) => {

packages/integrations/src/beszel/beszel-integration.ts

@@ -283,7 +283,8 @@ export class BeszelIntegration extends Integration {
         if (!clientId && typeof parsed.clientId === "string") {
           clientId = parsed.clientId;
           this.subscribeTopic(clientId, systemId, session.token).catch((err) => {
-            logger.warn("Failed to subscribe to rt_metrics topic", { error: err });
+            logger.warn("Failed to subscribe to rt_metrics topic, aborting SSE", { error: err });
+            reader.cancel().catch(() => {});
           });
           return;
         }

packages/integrations/src/mock/data/beszel.ts

@@ -350,12 +350,13 @@ export class BeszelMockService {
       };
       onMessage({ stats: record, containerStats: null });
     };
+    if (signal.aborted) return;
     await new Promise<void>((resolve) => {
       const interval = setInterval(emit, 1000);
       signal.addEventListener("abort", () => {
         clearInterval(interval);
         resolve();
-      });
+      }, { once: true });
     });
   }
 

packages/widgets/src/beszel-system-stats/component.tsx

@@ -2,7 +2,7 @@
 
 import { useCallback, useMemo } from "react";
 import { ActionIcon, Center, Menu, ScrollArea, Select, SimpleGrid, Stack, Text } from "@mantine/core";
-import { IconServer, IconQuestionMark } from "@tabler/icons-react";
+import { IconPlugConnectedX, IconServer, IconQuestionMark } from "@tabler/icons-react";
 
 import { clientApi } from "@homarr/api/client";
 import { useScopedI18n } from "@homarr/translation/client";
@@ -77,7 +77,7 @@ export default function BeszelSystemStatsWidget({
     { staleTime: 30 * 1000, enabled: !isLive && systemReady && selectedSystem !== "" },
   );
 
-  const liveData = useLiveStats(integrationIds, selectedSystem, isLive && systemReady);
+  const { data: liveData, error: liveError } = useLiveStats(integrationIds, selectedSystem, isLive && systemReady);
 
   const activeStats = isLive ? liveData : statsResult;
 
@@ -142,6 +142,19 @@ export default function BeszelSystemStatsWidget({
     );
   }
 
+  if (isLive && liveError && !liveData) {
+    return (
+      <Center h="100%">
+        <Stack align="center" gap="sm" p="md">
+          <IconPlugConnectedX size={40} />
+          <Text size="sm" c="dimmed" ta="center">
+            {t("error.internalServerError")}
+          </Text>
+        </Stack>
+      </Center>
+    );
+  }
+
   return (
     <ScrollArea
       h="100%"

packages/widgets/src/beszel/_shared/use-live-stats.ts

@@ -14,14 +14,17 @@ interface LiveStatsData {
 
 export const useLiveStats = (integrationIds: string[], systemId: string, enabled: boolean) => {
   const [data, setData] = useState<LiveStatsData | null>(null);
+  const [error, setError] = useState<Error | null>(null);
 
   const integrationKey = integrationIds.join(",");
   useEffect(() => {
     setData(null);
+    setError(null);
   }, [systemId, enabled, integrationKey]);
 
   const onData = useCallback(
     (incoming: { stats: BeszelSystemStatsRecord; containerStats: BeszelContainerStatsRecord | null }) => {
+      setError(null);
       setData((prev) => {
         const systemStats = [...(prev?.systemStats ?? []), incoming.stats].slice(-MAX_BUFFER);
         const containerStats = incoming.containerStats
@@ -33,10 +36,14 @@ export const useLiveStats = (integrationIds: string[], systemId: string, enabled
     [],
   );
 
+  const onError = useCallback((err: unknown) => {
+    setError(err instanceof Error ? err : new Error(String(err)));
+  }, []);
+
   clientApi.widget.beszel.subscribeSystemStats.useSubscription(
     { integrationIds, systemId },
-    { enabled: enabled && systemId !== "", onData },
+    { enabled: enabled && systemId !== "", onData, onError },
   );
 
-  return data;
+  return { data, error };
 };