Paginate beta history and refresh pages from events

src/lib/ui/beta-updates.ts

@@ -0,0 +1,30 @@
+/** Coalesce pushes, serialize refreshes, and recover missed events after reconnect or tab activation. */
+export function betaUpdates(load: () => Promise<unknown>, betaId?: () => number): () => void {
+    let timer: ReturnType<typeof setTimeout> | undefined;
+    let stopped = false, running = false, pending = false;
+    const schedule = () => {
+        pending = true;
+        if (stopped || running || timer || document.hidden) return;
+        timer = setTimeout(async () => {
+            timer = undefined;
+            if (stopped || document.hidden) return;
+            running = true; pending = false;
+            try { await load(); }
+            catch { /* The page owns its error state; later events can retry. */ }
+            finally { running = false; if (pending) schedule(); }
+        }, 200);
+    };
+    const changed = (event: Event) => { if (!betaId || (event as CustomEvent).detail?.betaId === betaId()) schedule(); };
+    const visible = () => { if (!document.hidden) schedule(); };
+    window.addEventListener('ec:beta-changed', changed);
+    window.addEventListener('ec:pipeline-connected', schedule);
+    window.addEventListener('ec:fleet-changed', schedule);
+    document.addEventListener('visibilitychange', visible);
+    return () => {
+        stopped = true; clearTimeout(timer);
+        window.removeEventListener('ec:beta-changed', changed);
+        window.removeEventListener('ec:pipeline-connected', schedule);
+        window.removeEventListener('ec:fleet-changed', schedule);
+        document.removeEventListener('visibilitychange', visible);
+    };
+}

src/lib/ui/stores/pipeline.ts

@@ -26,6 +26,11 @@ function updateDeployment(id: string, mutate: (d: PipelineDeployment) => void):
 export function startPipelineStream(): (() => void) | undefined {
     if (!browser || source) return;
     source = new EventSource('/api/events/pipeline');
+    source.addEventListener('open', () => window.dispatchEvent(new Event('ec:pipeline-connected')));
+    source.addEventListener('beta-changed', event => {
+        try { window.dispatchEvent(new CustomEvent('ec:beta-changed', { detail: JSON.parse((event as MessageEvent).data) })); }
+        catch { /* Reconnect refreshes authoritative state if an event is malformed. */ }
+    });
     for (const event of ['server-changed', 'server-state', 'deployment-opened', 'fleet-invalidated']) {
         source.addEventListener(event, () => window.dispatchEvent(new Event('ec:fleet-changed')));
     }