Preserve loaded logs across same-server fleet updates

src/lib/ui/components/LogPanel.svelte

@@ -37,6 +37,7 @@
     let stickToBottom = $state(true);
 
     const refresh = createLogRefresh({
+        onReset: () => { data = {}; refreshError = ''; },
         onLoading: value => { loading = value; },
         onError: message => { refreshError = message; },
         onData: (key, body) => {
@@ -88,7 +89,6 @@
         }
         parts.push({ text: line.slice(start), match: false }); return parts;
     }
-    $effect(() => { server; data = {}; refreshError = ''; });
     $effect(() => {
         const target = { server, key: active, lines };
         const auto = autoRefresh;

src/lib/ui/log-refresh.ts

@@ -14,6 +14,7 @@ export interface LogResponse {
 
 interface Selection { server: string; key: string; lines: number }
 interface Options {
+    onReset: () => void;
     onData: (key: string, response: LogResponse) => void;
     onError: (message: string) => void;
     onLoading: (loading: boolean) => void;
@@ -73,6 +74,9 @@ export function createLogRefresh(options: Options) {
         automatic = enabled;
         interval = pollMs;
         if (changed || pausing) cancel();
+        // Fleet updates can replace the parent server object without changing
+        // this identity. Only navigation to a different server invalidates logs.
+        if (selection?.server !== target.server) options.onReset();
         if (changed) { selection = target; options.onError(''); }
         if (!selection?.key) return;
         if (automatic) stopPolling = pollVisible(refresh, interval);