perf: optimize app startup and background lifecycles

src/lib/performance-diagnostics.ts

@@ -0,0 +1,91 @@
+import { invokeIpc } from '@/lib/api-client';
+
+type LongTaskAggregate = {
+  count: number;
+  totalDurationMs: number;
+  maxDurationMs: number;
+};
+
+type MainPerformanceSnapshot = {
+  capturedAt?: number;
+  eventLoopDelayMs?: number;
+  processes?: Array<unknown>;
+  windows?: number;
+  webContents?: number;
+  gpu?: Record<string, string>;
+  background?: {
+    activity?: { visible?: boolean; module?: string | null };
+    leaseCount?: number;
+  };
+};
+
+/**
+ * Installs development-only, aggregate renderer diagnostics. No URLs, page
+ * content, prompts or file names are retained or sent to Main. Production
+ * builds return a no-op cleanup so this cannot become a hidden polling task.
+ */
+export function installRendererPerformanceDiagnostics(): () => void {
+  if (typeof window === 'undefined' || window.electron?.isDev !== true) {
+    return () => undefined;
+  }
+
+  const longTasks: LongTaskAggregate = {
+    count: 0,
+    totalDurationMs: 0,
+    maxDurationMs: 0,
+  };
+  let firstPaintMs: number | null = null;
+  let disposed = false;
+  let paintFrame = 0;
+
+  const observer = typeof PerformanceObserver === 'undefined'
+    ? null
+    : new PerformanceObserver((list) => {
+      for (const entry of list.getEntries()) {
+        const duration = Math.round(entry.duration * 100) / 100;
+        longTasks.count += 1;
+        longTasks.totalDurationMs += duration;
+        longTasks.maxDurationMs = Math.max(longTasks.maxDurationMs, duration);
+      }
+    });
+
+  try {
+    observer?.observe({ type: 'longtask', buffered: true } as PerformanceObserverInit);
+  } catch {
+    // Chromium versions without the Long Tasks entry type are supported.
+  }
+
+  paintFrame = window.requestAnimationFrame(() => {
+    firstPaintMs = Math.round(performance.now() * 100) / 100;
+  });
+
+  const report = () => {
+    if (disposed) return;
+    const renderer = {
+      firstPaintMs,
+      longTasks: {
+        count: longTasks.count,
+        totalDurationMs: Math.round(longTasks.totalDurationMs * 100) / 100,
+        maxDurationMs: Math.round(longTasks.maxDurationMs * 100) / 100,
+      },
+    };
+    void invokeIpc<MainPerformanceSnapshot>('app:performance')
+      .then((main) => {
+        if (!disposed) {
+          console.debug('[performance]', { renderer, main });
+        }
+      })
+      .catch(() => undefined);
+  };
+
+  // A low-frequency sample is enough for the development panel and avoids
+  // adding another active request loop to normal renderer operation.
+  const timer = window.setInterval(report, 30_000);
+
+  return () => {
+    disposed = true;
+    window.cancelAnimationFrame(paintFrame);
+    window.clearInterval(timer);
+    observer?.disconnect();
+  };
+}