Reuse serialized server events across SSE connections

src/routes/api/events/servers/+server.ts

@@ -1,11 +1,14 @@
 import { observationReader } from '$lib/server/fleet/status.js';
 import { listServers } from '$lib/server/fleet/servers.js';
 import { statusEntry } from '$lib/server/pipeline/worker.js';
-import { subscribe } from '$lib/server/pipeline/bus.js';
+import { subscribe, type PipelineEvent } from '$lib/server/pipeline/bus.js';
 import { listTelemetry } from '$lib/server/fleet/telemetry.js';
 
 const encoder = new TextEncoder();
 const HEARTBEAT_MS = 20_000;
+// Bus subscribers receive the same event object. Reuse its complete frame
+// across connections without retaining events after delivery.
+const frames = new WeakMap<PipelineEvent, Uint8Array>();
 
 export async function GET() {
     let heartbeat: NodeJS.Timeout | null = null;
@@ -15,7 +18,12 @@ export async function GET() {
         start(controller) {
             unsubscribe = subscribe((event) => {
                 if (event.type === 'server-status' || event.type === 'server-telemetry') {
-                    controller.enqueue(encoder.encode(`event: ${event.type}\ndata: ${JSON.stringify({ ...event, serverNow: Date.now() })}\n\n`));
+                    let frame = frames.get(event);
+                    if (!frame) {
+                        frame = encoder.encode(`event: ${event.type}\ndata: ${JSON.stringify({ ...event, serverNow: Date.now() })}\n\n`);
+                        frames.set(event, frame);
+                    }
+                    controller.enqueue(frame);
                 }
             });
             const observation = observationReader();